1
FOOD ADVISORY
COMMITTEE AND DIETARY
SUPPLEMENTS SUBCOMMITTEE
FURAN MEETING
Tuesday,
June 8, 2004
1:55 p.m.
Bethesda Marriott
Grand Ballroom
5150
Pooks Hill Road
Bethesda, Maryland
2
PARTICIPANTS
Food Advisory Committee
Sanford A. Miller, Ph.D.,
Chairman
Linda Reed, Acting Executive
Secretary
Douglas L. Archer, Ph.D.
Patrick S. Callery, Ph.D.
Goulda A. Downer, Ph.D.
Johanna Dwyer, D.Sc, RD
Jean M. Halloran
Norman I. Krinsky, Ph.D.
Daryl B. Lund, Ph.D.
Margaret C. McBride, M.D.
Mark F. Nelson, Ph.D.
Robert M. Russell, M.D.
Carolyn I. Waslien, Ph.D.,
R.D.
Contaminants and Natural
Toxicants Subcommittee
Alex D.W. Acholonu, Ph.D.
Marion F. Aller, D.V.M., DABT
George M. Gray, Ph.D.
Ken Lee, Ph.D.
Henry B. Chin, Ph.D.
Temporary Voting Member
P. Joan Chesney, M.D.
FDA
Dr. Henry Kim
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C O N
T E N T S
PAGE
Welcome and Introductions
Sanford A. Miller, Ph.D.,
Chair 4
Conflict of Interest
Statement
Linda Reed, Acting Executive
Secretary, FAC 6
Opening Remarks
Nega Beru, Ph.D. 10
Scientific Overview of Furan
in Foods
Analytical
Methods/Occurrence
Dr. Kim Morehouse 22
Exposure
Jeremy Mihalov 36
Formation
Dr. Don Forsyth 49
Questions of
Clarification
58
Scientific Overview of Furan
in Foods
Dr. Glenda Moser 69
Questions of Clarification 86
Public Comment 98
Summary and Charge to the
Committee
Dr. Terry Troxell 98
Questions of
Clarification
105
Committee Discussion and
Recommendations 115
4
P R O C E E D I N G S
Welcome and
Introductions
DR. MILLER: I think I would like to get
started to enable us to
finish on time and give
people a chance to make
their planes, and so on.
First of all, let
me welcome the new
members of Food Advisory
Committee meeting for this
afternoon's session, which
will deal with furans
and the data necessary in
order to estimate the
risk of furans in food.
For the record,
when I call your name, I
going to introduce the new
members of the
committee. This meeting is being held in
conjunction with the
Contaminants and Natural
Toxicants Subcommittee of
the Food Advisory
Committee, and there several
members of that
committee that will be
sitting with us in our
deliberations.
When I call your
name, will you please
just repeat your name and
the institution with
which you are associated.
First, Dr.
Acholonu.
5
DR. ACHOLONU: My name is Alex Acholonu,
Alcorn State University,
Mississippi.
DR. MILLER: Dr. Aller.
DR. ALLER: Marion Aller with the Florida
Department of Agriculture
and Consumer Services.
DR. MILLER:
Dr. Gray.
DR. GRAY: George Gray with the Harvard
School of Public Health.
DR. MILLER: Dr. Lee.
DR. LEE: Ken Lee with Ohio State
University.
DR. MILLER: Dr. Chin.
DR. CHIN: Henry Chin with the National
Food Processors Association.
DR. MILLER: Dr. Chesney.
DR. CHESNEY: I am Joan Chesney. I am
Professor of Pediatrics and
Infectious Diseases at
the University of Tennessee
and also the title you
see on the roster at St.
Jude. I am also here
representing the FDA
Pediatric Drug Subcommittee.
DR. MILLER: Thank you.
Since we have some
new members, we are
6
required to repeat the
discussion of conflict of
interest for this particular
issue on furans.
Linda Reed, who is
Acting Executive
Secretary of the Food
Advisory Committee, will read
them.
Conflict of
Interest Statement
MS. REED: Good afternoon, everyone. As
Chairman Miller indicated, I
am Linda Reed, the
Acting Executive Secretary
of the Food Advisory
Committee meeting. I would like to welcome
everyone and particularly
our member from CDER.
I need to read the
conflict of interest
statement into the record
again.
The authority to
grant permission to
borrow Special Government
Employees currently
serving on an advisory
committee in a sister
center, in this case, the
Center for Drug
Evaluation and Research, is
granted to the
Associate Commissioner for
External Relations, Mr.
Peter Pitts.
Relying on that authority, Mr. Pitts has
signed a memorandum granting
permission for Dr. P.
7
Joan Chesney to serve as a
temporary voting member
for this portion of the
meeting concerning furan on
June 8, 2004. Dr. Chesney will represent, as she
just indicated, the
Pediatrics Advisory
Subcommittee of the
Anti-Infective Drugs Advisory
Committee.
Because of the
breadth of topics to be
discussed at this meeting,
all of the members and
temporary voting member have
been screened for any
and all financial interests
associated with
regulated industry.
Based on this
review, FDA has determined
in accordance with 18 U.S.C.
Section 208(b)(3) to
grant general matters
waivers to Dr. Marion Aller,
Dr. Douglas Archer, Dr.
Johanna Dwyer, Dr. George
Gray, Dr. Norman Krinsky,
Dr. Margaret McBride, Dr.
Sanford Miller, Dr. Robert
Russell, and Dr. Carolyn
Waslien.
The granting of
these waivers permits
these individuals to
participate fully in the
matters before the
committee. Copies of the waiver
statements may be obtained
by submitting a written
8
request to the agency's
Freedom of Information
Office, Room 12A-30 of the Parklawn Building.
In an effort to
enhance consistency within
FDA, the agency has recently
adopted a policy
whereby all public
commenters will be asked to
report any personal
financial interests that could
be affected by the
committee's deliberations. A
copy of the policy was
provided to any individual
who registered to make
comments at this meeting.
Additional copies of the
policy may be obtained
from the registration desk.
Similarly, we have
asked all of our guest
speakers to complete a
financial interest and
professional relationship
certification for guests
and guest speakers to
identify any potential
conflicts of interest.
Dr. Don Forsyth
and Dr. Glenda Moser will
be the guest speakers at
this portion of the
meeting. Both have indicated they have no
financial interests in the
food industry.
I would like to
thank for your attention
and I will turn the meeting
back over to Dr.
9
Miller.
Thank you.
DR. MILLER: Thank you, Linda.
As a matter of
procedure, each of the
speakers have been assigned
a time for their
presentation, and in order
for us to make certain
we get through the
presentations, and most
important of all, the
discussion, I intend to be as
ruthless as I can in keeping
the time.
We have several
limitations on our time.
For one thing, we have to be out of here by 6
o'clock at the very
latest. Otherwise, as I
indicated this morning, we
may be involved in
somebody else's wedding.
Also, there are
some of you who have
planes to catch, and in
order for the committee to
complete its business, which
will be explained in
just a moment, it is
important that we stick to the
time schedule.
The first
presenter is Dr. Nega Beru of
the FDA, who will provide
the background and
discuss the charge to the
committee.
10
Opening Remarks
DR. BERU: Thank you, Dr. Miller, and good
afternoon. My name is Nega Beru. I am the
Director of the Division of
Plant Product Safety in
CFSAN's Office of Plant and
Dairy Foods.
My purpose here
today is to provide you
with some of the background
on furan in foods to
set the stage for the scientific overviews that
will follow immediately.
I will also lay
out what input we are
seeking from the committee.
The structure of
furan is depicted on this
slide. It is a 5-member O-ring with two double
bonds. It goes by a number of names as shown on
this slide also, has a
molecular weight of 68, a
melting point of -85.6
degrees Celsius, and a
boiling point of 31 degrees
Celsius.
This last
property, it is fairly volatile,
may be important with
respect to how much furan
consumers are exposed to in foods as consumed.
Furan is a
colorless liquid that is used
in some segments of the
chemical manufacturing
11
industry. It is used, for example, as a solvent
for resins and in the
manufacture of lacquers.
It was the subject
of a 2-year bioassay by
the National Toxicology
Program in 1993. As a
result, it is listed in the
Department of Health
and Human Services report on
carcinogens, because
it was found to cause cancer
in rodents in the NTP
study.
Furan is formed in
food during traditional
heat processing techniques,
such as cooking and
canning. Its mechanisms of formation are beginning
to be elucidated, and there
appear to be a number
of them.
Later in this
session, Dr. Don Forsyth
from Health Canada will
present to you their
studies on mechanisms of
formation of furan in
foods.
The discovery of
furan in foods is not
new. Furan has been reported in a small number of
foods starting as early as
the 1960s, although very
little quantitative data exists in the literature.
Furan was found in
coffee, canned meat,
12
baked bread, cooked chicken,
sodium caseinate,
hazel nuts, soy protein
isolates, hydrolyzed soy
proteins, rapeseed protein,
fish protein
concentrates, and caramel.
What is new here
is that FDA has developed
a quantitative method to
measure low levels in food
and has found that furan
forms in a wider variety
of foods than previously
thought including in some
baby foods.
In addition to
FDA, Health Canada and
NFPA, together with some of
its members, are
investigating furan levels
in foods, and, in fact,
FDA, Health Canada, and NFPA
are also currently
collaborating In a round
robin evaluation of the
method that was developed by
FDA.
FDA's finding was
made during
investigations aimed at
confirming a report in the
scientific literature that
furan forms when apple
juice is irradiated. As part of that
investigation, a number of
non-irradiated, but
processed foods were also
evaluated using a
semi-quantitative method.
13
In the exploratory
survey we posted on the
web on May 7, we used a more
refined quantitative
method. FDA initially concentrated on foods that
appeared to have high levels
during the initial
screen using the
semi-quantitative method. FDA
also analyzed foods that
didn't necessarily have
high levels in the initial
survey, but could
potentially result in high
exposures based on
consumption data.
For each type of food,
foods were obtained
from two to three
manufacturers, and, in addition,
to get at the lot-to-lot
variation, two lots were
examined per food.
Foods that were
tested include baby foods,
such as apple juice,
applesauce, sweet potatoes,
carrots, and green beans,
infant formulas, both
liquid and powder, and adult
foods, such baked
beans, soups, chilis,
spaghetti sauce, tuna,
coffee, and chicken broth.
Over 160 samples
were tested in the
exploratory survey including
replicas of the same
brand or product, and the results
ranged from
14
nondetectable to
approximately 100 parts per
billion furan.
Right after my
presentation, Drs. Kim
Morehouse and Jeremy Mihalov
will present more
detailed results of the
survey, as well as the
exposure assessment that was
based on the results.
FDA made the data
collected in this
exploratory survey public on
May 7 by posting them
on the FDA's web site. At the same time, we posted
on the web a detailed
description of the method
used to analyze the food
samples, as well as a set
of questions and answers on
the issue of furan in
foods.
FDA also issued
two notices in the Federal
Register on May 7. One was to announce a call for
data on various aspects of
furan in foods, which I
will go into a bit
later. The other was to
announce this very meeting
of the Food Advisory
Committee and the
Contaminants and Natural
Toxicants Subcommittee.
When we announced
the data to the public,
we did so with a number of
message points. Of
15
course, we said that finding
furan in foods is a
concern because based on
studies in rodents, furan
is a potential carcinogen in
humans.
At the same time we made it clear that
furan certainly did not
appear suddenly in food,
its occurrence in food has
been reported before.
What is new here is the
discovery in a broader
variety of foods than
previously thought including
some baby foods.
We also said that
this discovery is not an
immediate public health
concern. This was based on
our preliminary exposure
assessment and a National
Academy of Science's review
of the toxicology of
furan done for NASA, and
this review is in your
briefing books, which
concluded that, one, the
weight of the evidence
suggests that furan is an
indirect carcinogen, and,
two, calculated and no
observable adverse effect
level of 80 mcg/kg body
weight per day.
Nonetheless, we
said that there are many
questions that must be
answered to improve the risk
analysis. Thus, we said that we intend to conduct
16
an expanded survey including
foods as eaten in
order to determine exposure
and risk to consumers
more accurately.
We also said that
we will look at what
additional studies are
needed to determine furan's
potential risk to human
health, as well as studies
on mechanisms of formation
and reduction methods if
the risk assessment warrants such studies.
Finally, we said
that we will seek input
from our Food Advisory
Committee and Contaminants
and Natural Toxicants
Subcommittee on what data are
needed to fully assess the
risk posed to consumers
by furan in foods, hence,
this meeting.
We intend to
evaluate all the available
data including input from
this meeting, and develop
an action plan to address
the issue of furan in
food. The action plan will certainly include an
expanded survey of foods,
but may also include
mechanisms of formation/reduction
in foods, as well
as toxicity studies to
address mechanism and dose
response.
In the call for
data we issued on May 7,
17
we asked for data in several
areas. With respect
to occurrence of furan in
foods, we asked for data
on the particular foods in
which furan occurs and
the levels in these foods, the formation and
occurrence of furan in
home-prepared foods as
opposed to, say,
manufactured foods, and on
environmental sources of
furan in which a typical
consumer is likely to be exposed.
With respect to
mechanisms of formation,
we asked for data on
possible mechanisms of
formation, as I mentioned
earlier, we wrote a
letter here about studies that Health Canada
conducted on mechanisms on
formation.
We also asked for
data on variables that
enhance or mitigate furan
formation in foods, on
the stability or dissipation of furan in foods, and
on the effect of
post-production practices, such as
consumer heating of canned
foods on the furan
levels in foods.
With respect to toxicology of furan, we
requested data on mechanism
of furan toxicity,
mutagenicity, and
carcinogenesis, on reproductive
18
and developmental
toxicology, and on metabolism of
furan in vivo including
characterization of any
reactive metabolites, and
the role of such
metabolites in producing furans
adverse effects
including carcinogenesis.
We also asked for
data on the diversity of
furan pharmacokinetics in
humans or the alteration
of furan metabolism as a result
of dietary,
medical, or environmental
interactions, and data on
whether sub-cytotoxic doses
of furan produce any
adverse effects, such as a
change in enzyme
activities or ATP levels.
Importantly, we
asked for data on the
effects of furan at doses
lower than those used in
the 1993 NTP study in order
to accomplish the
following objectives:
1.
To establish a dose-response curve for
the various toxicological
endpoints.
2. To determine whether furan toxicity,
including carcinogenesis, is
a threshold dependent
event.
3. To determine whether the carcinogenic
19
activity of furan is
secondary to its hepatotoxic
effects.
Last, FDA is also
asking for data on the
mutagenicity of furan in the
TA100 strain in the
Ames test, and the behavior
of furan in other in
vivo assays for mutagenicity or toxicity.
In the Federal
Register notice call for
data, we asked that data and
comments be submitted
to FDA by July 9, 2004. We also said that we would
share with the committee and
the subcommittee any
data or comments we received
by June 1.
To date, we have
not received any data on
any of the areas we
specified in the Federal
Register. We did, however, receive one comment.
That comment was from Dr.
James Coglin [ph],
president of Coglin &
Associates, a consulting firm
on food, chemical, and environmental
toxicology and
safety.
The comment
describes work done on various
heat-induced heterocyclic
compounds including furan
as antioxidants and urged
the committee and
subcommittee to consider the
beneficial health
20
protective effects of such
compounds in evaluating
the safety of furan in
foods.
This brings me to
the charge and the
question we are posing to
the committee. This, by
the way, are found in Tab 2
of your briefing
packages.
The Food Advisory Committee and
Contaminants and Natural
Toxicants Subcommittee are
being asked to provide input
on data that would be
helpful for further
evaluation of the potential
risks posed by the presence
of furan in foods.
Essentially, this
is the question we are
asking the committee. Taking into consideration
the data needs already
identified by FDA in the
Federal Register notice
requesting data on furan,
and the presentations you
are about to hear at this
meeting, are there any
additional data that are
needed to fully assess the
risk of furan in foods?
With that I will
end my presentation. I
trust this will provide an
adequate background for
the more detailed
presentations that follow, and I
thank you for your
attention.
21
DR. MILLER: Are there any questions for
clarification? Dr. Dwyer.
DR. DWYER: I wasn't clear from the data
needs if you are also
considering doing home-cooked
foods, for example, if I
made a sweet potato pie at
home, are you planning on
doing those, as well?
DR. BERU: I think in the long run, we
want to do that, and perhaps
even consider adding
furan to the total diet
study. Certainly, we have
done some preliminary work
on home cooking in terms
of what dissipation of furan
may take place during
normal home preparation of
meals of canned or
jarred foods, and Dr.
Morehouse will present some
of those data later.
DR. MILLER: Dr. Callery.
DR. CALLERY: Are you planning to also do
the Ames test on metabolites
of furan, especially
metabolites that may have
some predicted
toxicology?
DR. BERU: Well, at this point we are sort
of in a data collection
mode. We want to see what
work has been done out there,
and certainly we
22
intend to do what we can to
fill the data gaps
including those studies.
DR. MILLER: Thank you.
We next have three
papers dealing with
overview of furan in foods,
the first presented by
Dr. Kim Morehouse from
FDA. Ten minutes.
Scientific Overview
of Furan in Foods
Analytical
Methods/Occurrence
DR.
MOREHOUSE: Hello. My name is Kim
Morehouse and I am a
research chemist with the
Office of Food Additive
Safety, Division of
Chemistry Research and
Environmental Review. My
collaborators on this
project have been Ms.
Patricia Nyman, Mr. Timothy
McNeal, and Dr. Gracia
Perfetti.
Today, I am going
to present some data
that we have obtained on
furan in foods and sort of
explain to you why we got
into this in the first
place, even a little bit
more than what Dr. Beru
has presented already.
As was noted
earlier, during our
investigation of the
possible formation of furan by
23
ionizing radiation, we noted
that heating the
sample caused an increase in
the amount of furan
that was detected.
This increase was
not due in an increase
in the volatility of the
furan, but rather was
indeed due to generation of
furan.
We also noted the
presence of furan in
pasteurized apple juice that
we had purchased
locally at a store, but that
furan was not present
in apple juice that we
prepared fresh in our
laboratory.
This led us to
investigate the presence of
furan in heat-processed
foods, and we started
looking at various
foods. Originally, we were just
looking at it from the
standpoint of comparing
radiation treatment to heat
treatment of foods, so
we were doing a very random
sampling of products.
Basically, I just went
through the store, picked up
samples off the shelf that
were canned and
pasteurized products, and
this was a quick
semi-quantitative
determination. We weren't as
determined that we had to
have exact numbers, but
24
rather an order of magnitude because we were just
trying to say was the
radiation going to
significantly increase the
amount of furan that
would be present in the
total diet at that time.
However, as we got
further into this
project, we began to realize
that there was a large
number of foods for which
furan was present and in
substantial amounts, and it
became clear that we
needed to look at it
further, as well as needed to
know the quantitative
numbers that were there, not
just from a qualitative
standpoint.
So, we modified
our procedure. In order
to do this, we were using
static, headspace
sampling with gas
chromatograph determination with
mass spec detection. Our quantitation was based on
stable isotope dilution, as
well as standard
addition with known amounts
of furan to each food
product.
It is important to
note that we were doing
it on each food product
because each food product
had a different partitioning
coefficient of the
furan between the headspace
and the sample.
25
This method has been peer verified within
our lab group itself by
three different scientists,
as I mentioned earlier, and we are currently
participating in a round
robin study of the method.
Basically, what we
did was we took for
what I call liquid samples,
we took 10 grams of the
sample from the food
container and placed it into a
headspace vial. For solids and semi-solids, we
took 5 grams of the sample,
added 5 grams of water
in the headspace vial. The headspace vial was then
sealed and analyzed.
For some products,
it was necessary to
homogenize the sample, and
for those products they
were homogenized on ice
either using a blender or a
tissue homogenizer. After the samples were sealed
upon the addition of either D4 furan or furan if
necessary. They were vortexed to ensure adequate
mixing of the samples.
It was important
to make sure that we did
have adequate mixing because
we noted that when we
did not, we retained rather
spurious results, but
upon proper control of our
samples with proper
26
mixing and everything, we
were able to obtain
extremely good quantitation.
For our studies,
we listed limits of
quantitation on the data
tables that were presented
on the web. We used rather conservative estimates
of those limits, and for
liquid samples, we
determined that was about 2
ng/g, and for solids,
it was about 5 ng/g.
Like I said, these values are fairly
conservative, however, we
know that our limits of
detection are much lower
than that. For liquid
samples, we estimate those
to be about 0.7 parts
per billion, and for the
solid matrices, about 1.5
parts per billion.
As Dr. Beru
mentioned earlier, we selected
foods based on that initial
survey that we were
doing during our radiation
studies, as well as from
the literature reports of
foods that were known to
contain furan, and using the
FDA database to
determine which ones were higher
consumption foods.
For each food
analyzed, we analyzed from
either two or three brands,
and usually from two
27
different lots per brand. Using this data, we
undertook a systematic
manner to obtain
quantitative data.
I am going to go
through classes of some
of the foods that we looked
at. From the infant
formulas, we looked at
powders, concentrates, and
what are called ready to
feed foods. The
concentrates and powders
were prepared according to
label directions, placed in the vials and analyzed.
The ready to feed, of
course, are already ready to
feed, so they were just
simply transferred into the
vials.
You can see that
we have a range for the
powders of non-detected to 2
parts per billion, for
concentrates of non-detected
to 15, and for the
ready to feed, non-detected
to 13.
For the powder and concentrate, they are
based on what would have
been consumed.
The ranges I am
listing here is because
you still see in the next
presentation on the
exposure estimates, the range is what is used for
doing that calculation.
28
For some of the
baby foods that we have
analyzed, you can see the apple juice range from 2
to 8, and you can go on down
the list up to the
sweet potatoes and garden
vegetables, which were up
to 100 part per
billion. Again, you can see that
we do have a fairly large
range. Again, the garden
vegetables, we are talking
about three
manufacturers and two lots
per sample.
For some of the
adult foods, we have done
a lot more work. You can see that we range from
bread, where it is
non-detected to below our
quantitation level. When we have less than 2
there, that means we can
detect it, but it was
below our quantitation
level, and in the cases of
the tuna and the canned
meats, we listed as less
than 5. That means it was within our detection
limits, but below our
quantitation level again.
Again, you can see
the spread of the
numbers that we are seeing
and the various
different types of products
that we have been able
to analyze so far.
Just so you don't think it is
all so bad, from our
original survey, we do know
29
that many foods do not contain
furan, some of those
listed here, and you will
notice that man of these
foods are fairly high
consumption products, such as
milk and margarine and yogurt nowadays type of
thing. We also included pasteurized eggs and
potato chips in our original
survey, as well.
I was asked the
question about the heating
the products. We haven't gotten to the point yet
where we are actually cooking unprocessed foods to
look at that, but it is
something we do intend to
do eventually, but what we
did look at was what
about the foods from the can
and if you heat them.
For the foods we
looked at here, a very
limited preliminary study,
we did chicken broth,
two different pastas, and
the infant food sweet
potatoes. The pasta No. 2 and the sweet potatoes
were only treated one way,
that is why there is no
second bar there, but you
can see from the pasta
sauces and the sweet
potatoes, there is not what I
call a significant change upon heating, whereas,
with chicken broth where you
basically have water,
and not much lipids or
proteins to be holding back
30
the furan, it does
substantially decrease.
So, depending upon
what the food would be,
you would either lose the
furan or not, and this
gives us a little bit of
idea that we may have less
furan actually in the
consumption than what would
actually be in the food as
we are opening up the
jars.
For the heated
samples, they were heated
basically on a hot plate in
an open environment
until they boiled for about
10 minutes. In the
microwave, they were heated
to boiling, usually for
about a minute for the
chicken and pasta. The
sweet potatoes, they were
heated what I call until
they were tepid, similar to
what a consumer would
have done.
What is
ongoing? We are obviously
analyzing more foods. This was set as just a
preliminary survey so far,
we are doing a lot more.
We are now looking at foods
based on using the USDA
consumption database to say
what are some of the
other high use foods that we
should go ahead and
analyze that we haven't
already done before.
31
Again, still
looking at foods that have
been reported in the
literature that contain furan
for which no quantitation is
available in the
literature. It should be noted that in most
literature they would state
that they found furan,
but would not state what the
amount was, they
didn't quantitate the amount
there.
Of course, we are
going to continue to
investigate the effects of
heating on the
concentrations of furan.
For those who
would like to see the full
tables, of course, the
entire method that we used
is available on the web site
as was stated earlier,
as well as all the foods
that have been analyzed.
Thank you.
DR. MILLER: Questions?
DR. ARCHER: A
question, just curiosity.
What do you make of the
potato chip data?
DR.
MOREHOUSE: There was no furan in
potato chips.
DR. ARCHER: Any hypotheses?
DR.
MOREHOUSE: Nope. Again, you are hear
32
later on some of the
mechanisms, and some foods
that we saw high amounts of furan in, we look at
some of the mechanisms that
have been proposed for
where furan is coming from,
and they don't
correlate with the products,
so obviously, there is
multiple mechanisms,
multiple pathways, and potato
chips was one of the things
that we thought would
contain furan, and did not.
DR. DOWNER: Thank you very much.
It seems to me that the higher fat foods
tended not to have furan
detected. I want to ask a
little bit about the milk,
though. Were you able
to look at fat-free milk, 1
percent, 2 percent,
regular milk to see if there
were any detectable
differences in those grades
of fat content in the
milk with respect to furan?
DR.
MOREHOUSE: That was back from the
survey work, and I believe
all we did was whole
milk, and we didn't see any
furan in the whole
milk, so we didn't bother
with looking at any of
the others. We figured if it wasn't in whole milk,
why would it be in the
others.
33
DR. MILLER: Dr. Waslien.
DR. WASLIEN: I was particularly concerned
with the furan content of
formula, maybe
non-detectable, the 13
sounds low when you are
looking at a gram quantity,
but if an infant
consumes a liter a day, you
are up there in the
levels.
I went and looked
at the l.d., the least
dose for mice or rats, and
the calculated based on
that, of course, we don't have
any data for doses
for humans, would indicate
that the amount of furan
taken in is 13, and the dose
that is least
detectable or least risk is
something like 12, so
you are getting close for
some of those infant
formulas.
Now, my
calculation might be wrong, I just
sat and did it right now,
and we are encouraging
infants to drink less than a
liter of milk a day,
but it is a concern, and
that was my major worry.
DR. MILLER: That's true, but the issue
that we are concerned with
here is what work would
we suggest to the agency in
order to get enough
34
data in order to be able to
come to that
conclusion.
DR. WASLIEN: Well, partly I would think
one of the things you might
want to look at is
age-related differences in
metabolism since a
newborn infant has all kinds
of other metabolic
differences.
DR. MILLER: Hold that thought.
DR. WASLIEN: Okay.
DR. MILLER: Dr. Chesney.
DR. CHESNEY: I also have many, many
thoughts as you do, but for the moment, I wondered
if you could clarify the
infant formula slide for
me. I didn't quite understand
non-detectable-2-15-13, and
you also said based on
consumed, and I may have heard wrong. I wanted to
be sure I understood the
slide.
DR.
MOREHOUSE: The slide, that is the
range that we found for the
products that we have
analyzed. From
non-detectable to 2 for the powers,
from non-detectable to 13
for the concentrates, I
think it was, and the
powders and concentrates are
35
based on as it would have
been prepared by the
consumer for consumption.
In other words, we
took the powder and
made up the solution was it
was by label, so it is
based on the prepared
formula, not the powder
itself.
DR. CHESNEY: I understand. Thank you.
DR. MILLER: Dr. Chin.
DR. CHIN: Going
back to your table or
figure that showed the
effect of cooking on furan
levels in various foods,
there were I guess a
couple of bars where either
the value was zero or
there were no values.
DR.
MOREHOUSE: Those were because for the
second pasta sauce and for
the baby food, we did
not do the second treatment,
so the pasta sauce No.
2 was only heated, and the baby food was only
microwaved.
DR. CHIN: Thank you.
DR. MILLER: Dr. Aller.
DR. ALLER: A question again on the infant
formula. I know you mixed that. Was it heated
36
also?
DR.
MOREHOUSE: No, just mixed.
DR. DWYER: Just a question. Could
you
explain the difference
between limit of
quantitation and limit of
detection? It is just
that you can't above the
limit of detection, you
can't quantify until you get
to 2 parts per
billion, is that right?
DR.
MOREHOUSE: Right. Because of the
mass spectroscopy's
sensitivity, we can detect it
or we put very stringent requirements on
quantitation right now
because the method has not
been totally peer verified,
we felt that we didn't
want to say that we could do
1 part per billion,
even though we can see it,
but we don't want to
take the quantitation level
there yet.
DR. MILLER: Thank you.
The next speaker
is Mr. Jeremy Mihalov,
FDA, will talk about exposures.
Exposure
MR. MIHALOV: My name is Jeremy Mihalov,
Office of Food Additive
Safety. This also was done
37
with Dr. Michael
DiNovi. I am going to give you an
overview of our exposure
assessment for furan from
the consumption of adult and
baby foods.
I will start off,
give you an idea for the
model that we used to
estimate exposure, and this
is fairly similar to most
exposure assessments,
simply that the total
exposure for a person to
furan is the sum of the
exposures from each food,
overall foods that contain
furan, and exposure from
each of those foods is
simply the product of the
intake of that food modified by the concentration
of furan modified by the
concentration of furan in
that food.
We looked at adult
foods, baby foods and
also the infant formula, and
they were considered
separately.
The sources of our
data. For intake data,
we used the USDA 1994 to
1996 and 1998 USDA
Continuing Survey of Food
Intake by individuals.
This was a two-day survey,
two nonconsecutive days.
For each of the years, there
was about 5,000
people, so we have data for
basically 15,000
38
individuals, and we know
what they ate and how much
for each of those days.
We then looked at
the furan concentration
data which you just heard about, and we looked at
those lists of foods, and
looked at the survey
data, how much of those
foods did those people eat
multiplied by the
concentrations, and you can get
an exposure for each
individual.
This may be
somewhat of an iteration of
what you have already
heard. By looking at the
infant foods, we group them
into juices, fruit
purees, vegetables, mixed
chicken meals, had a
separate for infant formula.
For the adult
foods, we grouped them into
brewed coffee, instant
coffee, broths, soups that
contain meats, spaghetti
sauces, chili, pasta,
ravioli--they were both
canned--juices, pork and
beans, canned string beans,
canned tuna, canned
corn.
Just to go over some of the levels again,
within each food type, the
ones I just listed,
within the food types, there
wasn't a lot of
39
variability. Overall, the range, looking at all
the food types, went from
limited detection up to
about 125 mcg/kg.
Specifically,
looking at the infant food
groups, the highest were the sweet potatoes and the
garden vegetables, juices
were generally low, below
10 mcg/kg. The fruits and mixed meals were below
30. Other vegetables ranged between 30 and 60.
With the formula samples,
about half were below
limit of detection, and we
used the mean, which was
about 7 mcg/kg.
With the adult
foods, the coffee had the
greatest variability,
between limit of detection up
to 80. The juices, tuna, broth, sauces were all
generally low, below
15. The soups and the pork
and beans had a fairly wide
variation, the soups
being the highest. The chili, beef ravioli, and
spaghetti, the canned pastas
were between 30 and
100.
Going back to
discussing the model,
generally, when you do an exposure assessment,
there is a certain amount of
uncertainty, and we
40
compensate the uncertainty
with making certain
assumptions. Whenever we make an assumption, we
tend to make it
conservative, and this is typical
for agency exposure
assessments.
The first
assumption is that the
concentration of furan and
all the furan-containing
foods will be at the mean
within the food type, and
as I said there is generally
little variability
within the food types, so we
use the mean. When we
are looking at chronic
exposure, that is generally
how we do it.
Second assumption,
for all foods within a
food type that are shown to
contain furan, we
assume that it does contain
furan. In other words,
they have seen it in canned
chili, so when we did
the exposure assessment, we
assume anytime anybody
eats chili, it also contains furan, and as there is
more data collected in the
future, those
uncertainties could be
reduced.
The last
assumption is that the two-day
survey intake data that we used reflects a lifetime
exposure.
41
So, getting to the
final numbers, we used
the published April 20th concentration data that is
on the internet. Using that, for the adult foods
for people ages 2 and older,
that ate those foods,
the mean consumption was 0.3
mcg/kg-body
weight/day.
The 90th
percentile, which is what we
consider to be the heavy
consumer, on the upper end
of the distribution, is at
0.6 mcg/kg/day.
When we looked at the infant foods, and
these are age 1 or less,
that ate those foods, the
mean was 0.4 mcg/kg/body
weight, and the 90th
percentile was 1 mcg/kg.
We ran the
exposure assessment looking at
the individual foods just to
get a sort of profile
of how those different food
types contribute to
that overall mean, and this
is just a table of how
those foods contribute, coffee being the highest
out of the groups that were
tested, going down to
broths being negligible.
For the infant
formula, we took a slight
different approach, a more simple approach. There
42
is sort of standard numbers
for infant formula. In
order for an infant to
thrive, they need to consume
between 100 and 120
kilocalories per kilogram per
day, and infant formula is
usually formulated to
contain 0.8 Kcal/gram when
it is prepared, and I
used the mean furan concentration of 7 mcg/kg, and
if you do the arithmetic,
you can come out at a
mean exposure of 0.9
mcg/kg/day for an infant
consuming infant formula at
the level needed to
grow.
To sort of sum up
overall, the variability
of the furan levels within a
food type is generally
small, so we can pretty much
assume that additional
measurements within food
types won't have much
effect on the overall
exposure, however, because
the number of food types
that have been tested is
generally limited,
additional measurements in other
types of foods could have an overall effect on the
exposure, especially with
foods that are consumed
in high quantities or also
foods that have high
concentrations could affect
the exposure.
Thank you.
43
DR. MILLER: Dr. Waslien.
DR. WASLIEN: I did a quick recalculation
of my numbers, and I am off
by 1,000, so I skipped
nanograms in there. I just wanted to make that
correction.
But even so, I
think when you look at
infant formula, I hesitate to take the mean of
values, because the
likelihood of a person changing
from one formula to another
is not that high, so I
think you are looking at the
individual risk from
formula, so the child who is
consuming a formula
with 13, if it is a ready to
consume formula, is
probably going to be
consuming that reasonably
every day.
DR. NELSON:
I guess a similar question.
On the other food products,
did you use the mean in
your conservative estimate,
or did you use the
highest value?
MR. MIHALOV: We used the mean of all the
concentrations for all the
food types. Generally,
when you are looking at a
lifetime exposure, you
can pretty much assume that
if there is a
44
distribution over time as
you consume that food,
one day you might consume
the minimum, the next day
you may consume the max, but
over the course of
time, you are going to
consume at the mean.
Of course, if
there is additional data to
demonstrate that there is
some reason to why there
is a distribution, you know,
that could change, but
generally, for now we use
the mean.
DR. RUSSELL: Just a question of
information. With so many adult Americans eating
out, particularly in fast
food type restaurants, do
you have any data on fast
foods that have been
prepared under high heat
conditions?
MR. MIHALOV: Well, the survey data
includes restaurants and
home cooking. It is
essentially the survey is
given out and whatever
was eaten by those
individuals on those two days,
that is what they report.
DR. RUSSELL: But in your analysis of
foods that FDA has analyzed,
how many foods come
from that type of an
environment that were analyzed
actually? I noticed a lot of canned and jarred
45
things, very important for
infants particularly,
but I was just concerned
about the adult exposure.
MR. MIHALOV: Just looking at the list, I
would say a few of them are
probably restaurant.
Like I had said, if they
found it in a food, we
assume that it is in all
foods of that type, so,
for instance, the chili was
a canned chili, but we
assume that all chili
contained furan when we did
the exposure assessment, so
if they had chili at a
restaurant or if they made
it at home, that was
taken into account. If there is further data to
show that canned is higher
than home-cooked or
restaurant, then, we can
make that change.
DR. MILLER: Dr. Lee.
DR. LEE:
To continue that thread, I
assume that there is a fair
amount of looking at
canned and jarred foods
because the furan is fairly
volatile, so the packaging
method itself keeps the
furan present in the food,
is that a fair
assumption?
MR. MIHALOV: I couldn't say.
DR. MILLER: Dr. Nelson.
46
DR. NELSON: That would fit with the
infant formula data because
the powdered stuff is
typically spray dried where
you have a lot of
opportunity for dissipation of furan as opposed to
the canned concentrate or
ready to drink formula.
DR. MILLER: Do you want to respond to
that?
DR. LEE: I just want to continue along
that line of thinking. Have you ever considered or
does anyone have any data on
animal exposure,
particularly pets
consumption, because you
basically have a pretty
monotonous diet, and there
are pet foods that do come
in cans, so one would
expect that there would be a
fairly good exposure
there that you can model, is
there any interest in
looking at that?
MR. MIHALOV: That could probably be done
if we had concentration
data. I am sure that there
is some information on how
much food a typical
animal eats per day, but it would be pretty much as
simple as that, because a
pet would consume one can
or two cans, or something
along those lines, but
47
that could be one.
DR. MILLER: Dr. Chin.
DR. CHIN: I just wanted to comment a
little bit on the thought
about foods purchased at
restaurants. I think one of the other
considerations in terms of
foods that are purchased
at restaurants is that not
only do you consumer the
food at the restaurant, but
there are situations
where you have takeout food
and you take it home.
You might reheat
it in the microwave. We
have seen some limited data
where you take a food
from a restaurant, put it in
the microwave, and
under those circumstances,
at home, you would
produce some more furan.
DR. MILLER: Dr. Dwyer.
DR. DWYER: Just a question about the
exposure assessment. I am a nutritionist and so
when we use these kind of
data, we use the Iowa
State method for adjusting
the nutrients to pull in
the tails of the distribution.
Do you do that in
exposure assessments, as
well? In other words, you
have two days worth of
48
data, and so you are able to get an estimate of
usual intake from that, and
I wondered if you
adjust for that. The effect would be to change the
exposure, i believe.
MR. MIHALOV:
It doesn't sound familiar.
Basically, we take the
distribution of all the
consumers and pull a mean in
90th percentile right
from the distribution, but
not adjusting it.
DR. MILLER:
Dr. McBride.
DR. McBRIDE: In answer to Dr. Nelson's
point, I looked at that data
of the prepared
formula and the powdered
formula and thought maybe
it was a difference in processing, might be heating
it more when it is packaged
in liquid form.
I also did the
calculations for the worst
case scenario because that
is something I think you
were getting at, and if you
have a chubby
8-month-old who consumes a
liter of formula and 5
jar of sweet potatoes a day,
I assumed it had to be
at least 8 kilos to do that,
I got a worst case
scenario of 8 mcg/kg.
DR. MILLER: How much?
49
DR. McBRIDE: Eight.
DR. MILLER: Dr. Chesney.
DR. CHESNEY: Not why I am here, but the
fast food issue is
intriguing. I wonder if the
packaging contains
furan. Most fast food, you get
plastic containers to put it
in, and most people
reheat it in the
container. Just a thought.
DR. MILLER: Any more comments? If not,
thank you.
The next speaker is Dr. Don Forsyth from
Health Canada, who will take
about the formation of
furans.
Formation
DR. FORSYTH: First of all, I would like
to thank the committee for
the invitation to appear
here today on behalf of
Health Canada.
My name is Don
Forsyth. I am a research
scientist with the Food
Research Division of the
Bureau of Chemical Safety
with Health Canada in
Ottawa.
I would like to
take you through the
background as far as Health
Canada is concerned on
50
this issue. In late March 2004, we became aware of
U.S. FDA's investigation of
furan in canned and
bottle food
commodities. Upon learning that furan
has been shown to be
carcinogenic in rodent models
and has been classified as
possibly carcinogenic to
humans, we commenced method
development as of April
of this year for support of
the study of mechanisms
of formation, as well as a
preliminary survey of
Canadian food products.
Although furan is
used in industrial
processes, as has been discussed this afternoon, we
considered that the likely
source would be
formation during food
processing during the initial
start-up of our
investigations.
One thing we should mention about furans
in foods, however, is that
furan derivatives not
only have been reported in a
wide variety of foods
previously, but they are
also a significant flavor
and odor component in
coffee, cocoa, and various
cooked meat products.
So, these are
products or compounds, I
should say, which arise
naturally during the
51
processing and cooking of
various food commodities.
Furan itself, the
parent compound, has
been previously isolated in
coffee, canned beef,
sodium caseinate, soy and
rapeseed protein, as well
as caramel.
Looking through
the literature, you can
find a variety of possibilities
or comments from
previous authors working in
flavor and odor studies
about how these compounds
are formed.
The three that we
chose to look are the
thermal degradation of
carbohydrates or the
Maillard reaction, thermal
oxidation of lipid, and
decomposition of ascorbic
acid and its derivatives.
Just to take a
look at an older study
conducted by Persson and von Sydow back in 1974,
one of the first studies
that you find where they
are able to determine that
certain components in a
processed food could
increase the levels of furan
produced within that food
commodity under typical
canning conditions.
Using a beef,
water, and sodium chloride
formulation fairly typical
of the day for canned
52
beef products, they found
that even with just these
basic components, there was
fairly large levels of
furan produced, however,
with the addition of the
fat, as you see in the
second formulation shown
here, the levels increased
dramatically above the
formulation without the fat.
Then, when they
looked at the formulation
with a small amount of
carbohydrate added, they
found essentially no
increase over the basic
formulation of beef, water,
and sodium chloride,
and then finally with the
fourth different
formulation shown here, with
the fat and the
carbohydrate added in
addition to the other
constituents, you get levels
similar to the beef,
fat, water, and sodium chloride formulation.
So, in this
particular study, the authors
determined that the fat was
a precursor for the
formation of the furan.
Briefly looking at our own analytical
methods that we developed to
support these studies,
one was a headspace analysis
which we used for the
mechanisms of formation and
for the food survey,
53
and also the microextraction
technique, which is a
SPME related method
developed at Health Canada
which we applied to the food
survey results, which
we will be showing later on
in this presentation.
Both methods are
based on isotope dilution
using a d4 furan surrogate,
measurement by gas
chromatography/mass spectroscopy.
Formation
studies. We took some of the
test compound or precursor
to a small vial
containing 0.5 ml of
water. The vials were then
heated for 30 minutes at 118
degrees, conditions
not too dissimilar to
commercial canning
procedures, allowed to cool,
and then force cooled
to 4 degrees when the D4
furan surrogate was added,
so that we could analyze the resulting anilides
which may have formed during
this study.
The first table is
on the level of furan
which were formed with the
addition of ascorbic
acid and ascorbic acid
derivatives. Virtually all
of these compounds are
commercial antioxidants
which are used in foods, and
you can see that the
ascorbic acid with or without
the iron present,
54
iron is a known promotor of
oxidation and
therefore, would be expected
to, at least in some
cases, increase the amount of furan which would be
produced.
The sodium
ascorbate, again relatively low
levels. The dehydroascorbic acid, however, with
either the iron present or
absent gave higher
levels, almost 10 times
higher than the ascorbic
acid.
Isoascorbic acid,
again similar in this
case to the dehydroascorbic
acid, and the sodium
isoascorbate in the presence
of the ferric iron
produced almost again 10
times as much as the
sodium isoascorbate by
itself, but again, both half
the levels that we found with
the addition of
dehydroascorbic acid.
Finally, the
ascorbyl palmitate compound
produced fairly low levels
of furan as well.
Then, when we
looked at fatty acids and
oils, we found that the
degree of unsaturation in
the compound had an effect
with an increase in the
levels of furan formed
increasing as you go from
55
linoleic up to the linolenic
with an increase of
about 4 times in this case.
Now, in these two
fatty acid series, we
did see an increase in the
production of furan with
the addition of the ferric
iron, and in the case of
the oils, what you see in
the last four rows of the
table, again, a similar
increase as you go from the
trilinoleate up to the
trilinolenate, approximately
again roughly 4 times.
In this particular
case, with the oils,
the ferric iron had an
increase in the production
of the furan for the
trilinoleate, but not for the
trilinolenate.
Comparisons were
made between the reaction
products and the furan
standard, and as you can see
in this particular case, the comparison between the
linolenic acid reaction
mixture and the furan
standard, you get a very
similar pattern both for
the total iron chromatogram
as well as the
fragmentation pattern for
these two.
So, what we have
determined so far is that
at least in the model
systems that we have tested
56
so far, we found that the
polyunsaturated fatty
acids, such as the linoleic
and the linolenic, did
produce furans likely
through a free radical
formation mechanism with
ring closure resulting in
the formation of the furan,
and also decomposition
of ascorbic acid derivatives
particularly the
dehydroascorbic acid and the
isoascorbic acid also
led to the formation of furan.
Some of our survey
results in baby foods.
Here, we have a comparison
between our two
methodologies, the
microextraction technique in the
first column, and the static headspace in the
second.
Levels varied as
low as 6 parts per
billion, and went as high as
approximately 154
parts per billion in the
mixed vegetable. Each one
of these values that you see
is the average of two
individual analytical
determination for each
method.
When you look at
adult foods, we found
that the chili products had
the highest levels
amongst those that we
analyzed with levels ranging
57
up to as high 227, 236
depending upon the method
value, as well as 152, soups
there was a broader
range ranging from as low as
35 ppb up to
approximately 115, 117 ppb.
We have looked at
one stew product so far
with a value of
approximately 80 parts per billion,
one bean product with
relatively low value, 14
parts per billion.
The luncheon meats
that we looked, I
believe were both beef or
pork based, and they were
all relatively low with
levels down to 4 parts per
billion, and no higher than
approximately 30 parts
per billion.
Fresh brewed
coffee, as would be typically
served, would range between
14 to approximately 50
parts per billion.
Next steps for our
work at Health Canada
include further studies on
the mechanisms of
formation using additional
model systems, as well
as precursor fortified food
matrices.
Examining losses
of furan during food
processing and cooking
operations, as well as
58
further examinations of
canned and bottled
products. We also have a round robin method
validation study to
complete, and that is ongoing
as we speak, and we should
be reporting back on
that in just a few weeks.
Then, finally, to
continue updating our
health risk assessment as
new data becomes
available.
With that, I would
just like to thank
everyone for their kind
attention.
DR. MILLER:
Thank you.
Any comments or
questions?
Questions
of Clarification
DR. ACHOLONU: I was wondering, is it
advisable to check the
concentration of furan in
mixed vegetables? Could you justify using that?
Mixed vegetables, which has
different kinds of
vegetables put together,
what do you do?
DR. FORSYTH: The premise of that, of
course, is for health risk
assessment, in which
case we are interested in
consumption of food
commodities that are related
to a typical diet, so
59
this is one particular food
product that we
happened to analyze, and
that is essentially the
extent of our interest in it
at that point.
DR. ACHOLONU: But does it have any
scientific basis?
DR. FORSYTH: It has a scientific basis in
the sense that with that
particular food matrix,
those are the levels that
you are reaching. It
also brings to mind what is
causing that formation,
which is something that we
are certainly interested
in, because it doesn't fit
into the existing models
that we have pursued so
far. So, yes, I think it
has a lot of scientific
interest.
DR. MILLER: Dr. Krinsky.
DR. KRINSKY: Could you just describe the
conditions for generating
the furan from the
linolenic acid? Was this heated, cooked, baked, or
was it just linolenic acid
out of a jar?
DR. FORSYTH: I didn't actually conduct
this study myself. My understanding is that the
compound, which I believe
was 10 mg of the
precursor would have been
added to the vial
60
containing 0.5 ml of water,
and then that would
have been heated to the 118
degrees for 30 minutes.
DR. KRINSKY: Thank you.
DR. MILLER:
Dr. Lund.
DR. LUND: Looking at the Persson and von
Sydow data, I wondered if
you have had any comments
with regard to the
degradation of furan upon
prolonged heating.
Some of their data, at least on
the surface, would suggest
that upon prolonged
heating, you probably get
formation rates equal to
degradation rates because
the concentration is not
changing.
DR. FORSYTH: First of all, I am not sure
if that is what they were
alluding to or not. I
thought that data was to
look at probably losses of
furan due to revolatilization during heating and
processing in the kitchen.
I know that there
is some concern that you
may actually be creating
more furan with
post-processing sample manipulation, but I don't
know if anybody has actually
really looked at that
yet.
61
DR. MILLER: Dr.
Callery.
DR. CALLERY: We addressed part of this
already, but it's an
impressive amount of work that
you have done since
March. I have been looking at
this, and I admire you for being able to get so
much data so rapidly. I have a couple of little
questions, though.
The ascorbic acid
one in particular, from
what I remember the
structure of ascorbic acid,
it's a highly oxidized
species and it gets even
more oxidized readily, and
that you are actually
asking iron to participate
in this reaction to
facilitate an oxidation.
I think the point
I am trying to make is
that the furan is more like
a reduction or
elimination of water, a
couple water molecules, and
more a reduction. If
you looked at the oxidation
states of the various
carbons, they are not at a
higher oxidation state than
ascorbic acid.
So, it may be
something very different
going on here that is involving the metal in the
process of making furan, if
that is what you are
62
actually doing. I think the question was also the
yield that you are
addressing here, maybe there is
10 mg of ascorbic acid or I
am sure 10 mg of fat,
but that nanograms per gram
is incredibly small
yield in the process of cooking, so I am wondering
a little about that, too, if
you aren't just making
some furan this way out of
this particular
compound.
DR. FORSYTH: I have no doubt that the
yields, particularly with
the ascorbic acid tend to
be quite low, but typically,
levels used in food
are reasonably high, and
this wouldn't necessarily
be the only way that furan would be formed, and it,
of course, had been alluded
to earlier by one of
the other speakers, that we
undoubtedly will find
that there is multiple
pathways contributing to the
overall levels of furan
present in the food.
These are, I can't
stress strongly enough,
preliminary investigations
into possible means that
furan could be formed. There had been previous
work with some of the
ascorbic acid related
derivatives that had
indicated that a variety of
63
furans were formed during thermal degradation, and
this is what we were
attempting to follow up on
with this study.
DR. MILLER: Dr. Chin.
DR. CHIN: I would also like to compliment
you on doing such an
impressive amount of work in
such a short period of time.
Just a question in
terms of your thoughts
on other possible
precursors. Are you planning to
look at the possibility that
perhaps carotenoids
and similar types of
materials might be a precursor
also?
DR. FORSYTH: Our immediate plans, and we
are doing this as we speak,
looking at Meyer type
reactions at present.
DR. CHIN: Just a follow-up, and the
reason I am asking is
because in products like the
sweet potatoes where there
are amount of furan have
been detected, I mean those
materials are high in
carotenoids, whereas, they
are generally low in
fat, and I don't think the
ascorbic acid levels are
particularly high, so just a
possibility in terms
64
of another possible
precursor.
DR. FORSYTH: It
sounds like we will be
following up with you
shortly.
DR. MILLER: Dr. Dwyer.
DR. DWYER: Just a question more from
ignorance than anything
else. Are the methods that
you are using in Health
Canada and the Food and
Drug Administration's
methods the same? I just
looked at chili, and it
looked like the Canadian
chili was much more potent than the American chili,
and just wondered if there
were some way if they
are not the same method, if
there is some way to
get some comparable methods
in both countries or to
divide up the work and do
some round robin studies,
so that we are not
overduplicating things that are
basically the same trading
area.
DR. FORSYTH: Round robin testing is
underway. In our own case, it was set aside
because we were concerned
with what levels were
present in the Canadian food
supply, so that was
our first priority. Now that that is completed, we
do have the two methods
which we wish to compare,
65
not only against FDA's
method, but also any
industry methods which are out there, and we will
be doing that through the
round robin study.
DR. MILLER: Dr. Russell.
DR. RUSSELL: Yes.
Following up to Dr.
Chin, I also had wondered about the sweet potato,
but I was wondering if the
soup, it says soups in
both the FDA data and your
data, I was wondering if
there was any clues that
could be gotten with the
types of soups.
There was a three-
or four-fold variation.
What types of soups were
looked at?
DR. FORSYTH: I believe there was--I hope
there was a listing of the actual products that we
tested included in your
information package. In
any case, we have tested 30
products so far. We
hope to be testing more in
the near future but for
the time being, we will be
participating in the
round robin study first.
DR. MILLER: Dr. Chesney.
DR. CHESNEY: Again, just for
clarification, and this may
seem like a very
66
simplistic question, but is
it correct that the
furan is created by
oxidation of the ascorbic acid
products and the
polyunsaturated fatty acids, it's
a product of oxidation of
those entities, am I
correct?
DR. FORSYTH: I think with the ascorbic
acid, I would view it more as a thermal degradation
as opposed to an oxidation
per se, whereas, with
the lipids, it is a
radical-mediated oxidation
mechanism, yes.
DR. MILLER: Dr. Nelson.
DR. NELSON: Following up on Dr. Dwyer's
comment about the
equivalence of method or
recognition of each other's
method, I guess, would
the food supplies be
considered equivalent enough
for us to sort of accelerate
the database by again
sharing the activity? I don't know if we need the
same trading area, we have
to have a NAFTA
database.
DR. FORSYTH: Is that related to me?
Presumably, in Canada, we
find that we have
different branding as
opposed to U.S. foods, but in
67
cases where you have the
same manufacturer, I
personally can't see any
reason why the data
couldn't be used.
DR. MILLER: Dr. Downer.
DR. DOWNER: I just wanted to respond to
Johanna's question about the
chili. I think in
Canada, they may be using
Spam from looking at the
database here, so maybe that
is where the
difference is.
Thanks for a good
presentation. I am just
wondering about Dr.
Morehouse's presentation when
he looked at no furan
detected in some of the
different groups of foods,
particularly foods from
animal sources. I was thinking that perhaps
because it was a bit lower
in fat.
But on one of your
slides, when you talked
about the effect of canned
beef formation and you
added fats, it was really
the opposite. Could you
talk a little bit about
perhaps the differences
that were seen there?
DR. FORSYTH: Actually, in retrospect,
when you look at their study
versus our own results
68
on canned luncheon meats, I have concerns. It was
a 1974 survey, well,
different analytical
capabilities than we have
now, so I believe that
that work does bear out the
results that we were
finding in terms of the presence of fat promoting
the increase in furans.
However, I can't
reconcile the findings
that they reported in that
publication with our own
and also with FDA's current findings on luncheon
meats, which I would have
felt should be
comparable.
DR. MILLER: Dr. Dwyer.
DR. DWYER: Just a question again about
methods. Is there a standard method, or are you
driving toward a standard
method instead of
everybody having their own
method especially in
North America, it seems like
this might be
something to agree about one
way or another?
DR. FORSYTH: There has been a few
factors, time being one of
the largest.
Essentially, with the time
constraints that all of
the organizations have had,
you basically begin
69
with the people that you
have who know how to do
these types of analyses, and you ask them to come
up with a working method,
and I believe that is
essentially what has
happened here.
The next phase
will be these organizations
to have, and this is being
done as we speak, a
round robin study in which
case we all examine the
same food commodities and
see if we get, hopefully,
roughly the same
answers. Depending upon the
results of that study, there
would then be either
adjustments made or
discussions amongst the various
organizations to determine
why, if there are indeed
any, there are differences
in our results on these
particular food commodities.
DR. MILLER: Why don't we move on. Thank
you very much.
The next speaker
is Dr. Glenda Moser. You
have got 25 minutes.
Scientific
Overview of Furan in Foods
DR. MOSER: Thank you.
Well, I would like
to begin by thanking
the committee for inviting me today and say that my
70
talk is going to be a little
different than those
that have been presented up
until this point, and,
in particular, I am going to
be talking about some
in-life studies that we did
to try and determine as
best we could a mechanism
for furan-induced liver
tumors in mice.
In a two-year NTP
bioassay, there were
both non-neoplastic and
neoplastic findings in rats
and mice of both sexes. In particular, there were
neoplasms, cancer, in the
liver in the rats, and
cholangiocarcinomas in the
rats, as well as
mononuclear cell leukemia.
The important
thing here is that at 2
mg/kg, there was approximately
a 90 percent
incidence of
cholangios. In mice, there was an
increased incidence of
benign tumors of the adrenal
gland, as well as
hepatocellular tumors at both 8
at 15 mg/kg.
Here, what you see
is more of what I am
going to be talking about
today, is the incidence
of your hepatocellular
adenomas or your benign
tumors, hepatocellular carcinomas,
and then the
71
adenomas and the carcinomas
together in female mice
and in male mice, and you
see a dose-dependent
increase in both the males and the females.
Another important
factor for the study
that I am going to be
talking about is the
incidence of spontaneous
liver tumors in both male
and female mice. Historically, in your B6C3F1
mice, you will have
somewhere between 20 and 60
percent incidence of liver
tumors in control
animals. Usually, it's much lower in your female
mice. It is for that reason that we conducted our
two-year study in female
mice.
Sometimes it is
difficult when you have 40
or 50 percent incidence of
spontaneous liver tumors
to find an increase in male
mice.
Cancer, as we are
well aware, is a highly
complex, multistage process
that is operationally
divided into three stages,
namely, initiation,
promotion, and
progression. Initiators or
genotoxic agents directly
damage DNA. They change
the primary sequence of the
DNA.
Genotoxic agents
can be carcinogenic after
72
a single exposure, and, in
general, it is found
that genotoxic agents are
better carcinogens if
they also induce cell proliferation, so they can
fix those mutations.
Metabolism, there
are many carcinogens,
not only liver carcinogens,
but carcinogens in
other systems, the parent
compound is not
carcinogenic, but it is
metabolized or intoxicated
to its toxic moiety.
In the case of
furan, you have the
cytochrome 2E1 in the liver
that metabolizes the
furan to its toxic moiety.
There are a variety of
mechanisms of genotoxicity
which we are not going
to talk about today.
What we have here
is somewhat of a summary
of assays for genotoxicity
after furan exposure.
We have those that are
negative, those that are
positive, those that are
highlighted in mammalian
systems, and those that
aren't, are either in your
Salmonella or your
Drosophila.
In spite of the
fact that there are some
positive tests for
genotoxicity, furan is generally
73
considered to be
non-genotoxic. Non-genotoxic or
epigenetic agents, they are
generally believed to
clonally expand those
initiated cells.
They provide an
environment in which those
particular cells
opportunistically grow and expand,
that, in general, your
non-genotoxic agents require
multiple exposures, sometimes
over the course of
the entire life span of the
animal, and generally,
with your tumor-promoting
agents or your
non-genotoxic agents, it
requires high doses.
In the early
stages, tumor promotion is
generally reversible, so
that in a 13-week study
with furan, the animals were
dosed at 8 and 15 mg,
then, they were held for
either 6 months, 9 months,
or 15 months, and 18 months, and evaluated.
In these
particular studies, furan was not
reversible, particularly the
cholangiocarcinomas.
It is important
for us that B6C3F1 mouse
is the mouse used by the
National Toxicology
Program. Part of the reason that it is used is
that it is sensitive to
cancer, and that's both
spontaneous cancers, as well
as chemically induced.
74
In particular, the
liver, of the 500
compounds that the NTP has
evaluated, approximately
50 percent of them are carcinogenic in the mouse
liver. Really, that was the reason that we
conducted these studies was
to try and make some
association of what
relevance are these mouse liver
tumors to humans.
There are a whole
variety of non-genotoxic
mechanisms, we are not going
to talk about them
today. The one I do want to talk about is the
cytotoxicity in cell proliferation, that furan, in
short-term studies, is
necrotic to liver cells,
hepatocytes. It kills them.
After this, in
order for the liver to try
and maintain its homeostasis, we have regenerative
or compensatory cell
proliferation. There are
certain hypotheses that
believe that the mutations
that you may find in the
H-ras gene or some of the
other genes are secondary to
this cytotoxicity and
cell proliferation, that the
DNA is believed to be
inordinately sensitive to
mutation when it is
dividing. It is kind of spread out there, kind of
75
opening itself up, if you
will.
Liver
cytotoxicity, how do we determine if
a chemical is cytotoxic for the hepatocytes?
Commonly, that is done by
clinical chemistry, by
evaluating serum ALT,
alanine aminotransferase, or
sometimes SDH levels,
sorbitol dehydrogenase, and
secondly, by histopathology,
that liver sections
are stained with hematoxylin
and eosin, your H & E
stained section, you will
commonly find pycnotic
nuclei that generally the
nuclei of the hepatocytes
are blue, and those cells
that have been exposed to
a cytotoxic agent, their
chromatin and the nucleus
is sometimes so blue that it
is almost black.
You will find an inflammatory response.
You have the recruitment of
both your mononuclear
and your polymorphonuclears
to kind of clean up the
debris as a result of this
cytotoxicity, and
thirdly are the degenerated hepatocytes or the
cytoplasmic vacuolization.
We conducted a
13-week study in male
B6C3F1 mice. These animals were exposed by gavage
intergastrically 5 times a week. The dose levels
76
were 0.5, 2, 4, 8, and 15
mg/kg. We quantified
cell proliferation by BrdU. In these particular
studies, we used an osmotic
pump, a 7-day. The
advantage of that is that
the liver--the life span
of a hepatocyte in a mouse
is generally about 200
days, so at any one point in
time, you are only
going to have 0.5 percent of
your hepatocytes
dividing.
So, if we go over
the course of 7 days,
then, we accumulate all the
cells that are divided,
all the cell replication
that occurred in those 7
days.
So, this is an H
& E stained liver section
of the mouse, and what you
see here, you see the
inflammation that is common
after exposures to
cytotoxic agents. You have the influx of your
morphonuclear, of your
mononuclear and your
polymorphonuclear
neutrophils.
After you look at the incidence of liver
cytotoxicity, after 1, 3, 6,
and 13 weeks, you will
see that the highest doses,
you have a greatly
increased incidence of
cytotoxicity, also, at 8
77
mg/kg you have a significant
increase, and at 4,
you have an intermediate
response.
Cell proliferation. One of the markers,
the ways of quantifying cell
proliferation is the
labeling index that measures
the S phase of the
cell cycle. There are a variety of methodologies.
You can look at mitotic figures, quantify those.
You can look at KI67 gene,
you can look at PCNA, a
proliferating cellular
nuclear antigen that is part
of a quaternary complex.
For us, we used BrdU, bromodeoxyuridine.
It's a thymidine analogue,
so when the DNA is
replicating, in place of the
thymidine, a certain
percentage of the BrdU will
be incorporated.
Then, we have an antibody to the BrdU, so
we immunohistochemically
stain for cells that have
incorporated this BrdU. There are a variety of
routes of administration
depending upon what the
endogenous cell
proliferative rate is. You can use
a pulse. So, for instance, if you are looking at
cell proliferation in the
skin, you may inject IP
an hour later euthanize the
animals.
78
For us, there is
the cumulative is the
advantage, as I said
earlier, because you can find
out the cell proliferation that has occurred over a
period of time.
Quantifying, how
do we quantify this?
Well, by light microscopy,
we look at these
immunohistochemically
stained sections. [Off
microphone.]
I am sorry, excuse
me. At the 4 mg/kg,
these are the cells that
have incorporated the
BrdU. Over here, at 8, you will see many more of
them. So, what we do is we evaluate 2,000 hepatic
nuclei and determine the
percentage for those
nuclei that have
incorporated this stain.
In our 13-week
study, you will see that we
have a significant increase
at the 15 mg/kg at all
three time points, 1, 3, 6,
and 13 weeks. At our 8
mg/kg, which I found to be
interesting that your
calculations were 8 mcg/kg, you have a significant
increase at 1, 3, and 6
weeks. At 3 weeks, you
also have an increase in 2
and 4.
We also conducted
a study in female mice
79
in which they were exposed
to 00.5, 1, 2, 4, and 8
mg/kg, and you will see that
the highest dose of 8
mg/kg produced a significant
increase in your ALT
levels with an intermediate
response in the 4.
The SDH was
elevated in both the 4 and the
8 mg/kg. If you looked at the hepatic labeling
index, again, you saw a significant increase in
female mice at the highest
dose of 8 mg/kg, and no
other increases.
In light of this
data, we conducted a
carcinogenicity study, a
two-year study. It was in
female B6C3F1 mice. Our dose levels were 0, 0.5,
1, 2, 4, and 8. Eight, you will recall was the
dose that produced both
cytotoxicity and an
increase in labeling index, that we had 50 to 100
animals per group,
particularly in our lower groups
we wanted to be able to
detect the significant
increase if there was one,
so we increased the
number of animals.
They were exposed
for two years. They
were exposed by gavage, and
this was 5 times per
week.
80
We conducted
necropsies on these animals
after two years, and what
you will see here, on the
left, is a normal mouse
liver. This was an animal
that was exposed to 8 mg/kg, and at gross necropsy,
you will often find these
masses.
We quantified the
incidence of these
masses at necropsy. There was a significant
increase, 100 percent of the animals had liver
masses at the final
necropsy, and there was also a
significant increase at 4
mg/kg.
We evaluated H
& E stained liver sections
for inflammation.
As before, you will see that at
your 8 mg/kg, that there was
an increased incidence
of livers with both moderate
and marked subcapsular
inflammation or
cytotoxicity, and there was an
intermediate response at 4
mg/kg.
This is an H &
E stained liver section,
and what we have here is a
hepatocellular tumor.
It is a metastatic one as it
ended up being. You
can see how there is loss,
there is disruption of
the normal liver
architecture. So, we evaluated H
& E stained sections for
the presence of
81
hepatocellular adenomas,
carcinomas, and foci.
You will see at 4
mg/kg, there was a
significant increase in
foci. Foci are believed to
be pre-neoplastic liver lesions that have the
ability to progress on to
become benign or
malignant liver tumors.
At your 8 mg/kg,
you had a significant
increase in the incidence of
foci, adenomas, and
carcinomas.
What we say here
is that there is a very
good correlation between
cytotoxicity as measured
by ALT or SDH, and labeling
index, and the
incidence of liver
lesions. So, when those, at 8
mg/kg, where you had an
increased incidence of
cytotoxicity, you had an
increase in labeling
index, you also had an
increase of masses at
necropsy, and adenomas and
carcinomas
microscopically.
At 4 mg/kg, you
had somewhat ambiguous
intermediate responses in
the short-term assays,
and you had an increased
incidence of lesions or
masses at necropsy, and an
increased incidence of
82
pre-neoplastic lesions by
light microscopy.
So, in conclusion,
what we can say is that
this study demonstrated a
dose-dependent increase
in furan-induced liver
tumors in female B6C3F1
mice, and a relationship between the dose,
cytotoxicity, compensatory
cell proliferation, and
tumor induction.
An overview. In this particular study, we
have reproduced the results
of the NTP bioassay.
In the NTP bioassay, they
used 8 and 15 mg/kg.
They had an increased
incidence of liver tumors as
did we.
What we noticed
here is that there is a
threshold that doses below 4
mg/kg did not increase
the incidence of liver
tumors or produce the
short-term effects that
would suggest that they
would be hepatocarcinogenic.
At 13 weeks, I did
not show the data, but
at 13 weeks, we saw that
there was an increase in
cytotoxicity, there was an
increase in labeling
index. We have a stop group, so they were exposed
for 13 weeks, then, they
were held for an
83
additional 4 weeks. Both the labeling index and
the cytotoxicity returned to normal in that group.
There are other
chemicals with the same
proposed mechanisms -
chloroform, carbon
tetrachloride, theocitamide
[ph], a whole variety,
that the mutations or the
other events that we saw
in these genotoxicity assays
may be secondary to
hepatocyte cytolethality or
increased cell
proliferation.
This is a biologically plausible
mechanism. It makes sense that cells are killed,
that new cells are produced,
and that these
particular cells may be more
susceptible to DNA or
genetic damage.
The furan-induced
effects after short term
exposure are inhibited by
p450 inhibitors. We said
that furan is metabolized by
cytochrome p450-2E1 to
its toxic metabolite, it's a dialdehyde. If you do
studies in which you give
the animals the furan and
the p450 inhibitor, you do
not get an increase in
labeling index at these
doses. You do not get an
increase in cytotoxicity.
84
There are similar
pharmacokinetics in the
mouse and in the human in
vitro, and in general,
the rat metabolizes furan
slower than does either
the mouse or the human.
Future areas of
interest. It would be
interesting to know that if
you gave your animals
p450 inhibitors or maybe
developed a transgenic
mouse in which that
particular gene was knocked
out, would you get mouse
liver tumors.
Are liver tumors
due to the bolus dose?
So, unlike food where you
are taking a little bit
in all the time, we gave
them their furan in one
big dose the first thing in
the morning.
Are the positive genotoxic results, are
they due to direct damage to
the DNA, as some of
the genotoxicity assays
indicated, are they due to
the high doses, or are they
secondary to cell
proliferation or other phenomenon?
What are the
molecular or the gene
expression changes in liver
tumors? That is
something that we have been
looking at is to try
and find out are there growth factors, are there
85
other things, surrogate
markers that we could find
in the blood that might help
us identify those
chemicals that are possibly
carcinogenic, in
particular, liver
carcinogenesis, and, in
particular, those that do a
biocidal toxic
mechanism.
Do these same mechanisms occur for
cholangiocarcinomas? Is there a threshold for--and
I am sorry, these say
cholangiosarcomas, they
should be
cholangiocarcinomas--is there a threshold
for cholangiosarcomas,
similar to what we found
with the mouse liver?
Is the mode of
action of the
cholangiocarcinomas similar
to that of the mouse?
Do biliary tract epithelial
cells have
pharmacokinetic parameters
similar to that of
hepatocytes? It is the biliary epithelial cells
that are believed to be the
precursors of the
cholangiocarcinomas. What is
the relevance of the
mouse liver findings to
cholangiocarcinomas and
leukemia in humans?
This particularly
has to do with the
86
pharmacokinetic
parameters. What are the
concentrations in the organ
systems of interest?
Are there
populations of humans that are
susceptible to furan-induced effects and is age a
factor, whether it be the
baby food or the elderly?
There is a lot of evidence
that indicates that
infants don't have the same
intoxification or
detoxification systems as
adults, so does that make
them more susceptible or
less susceptible?
Finally, I would
like to thank my
colleagues, those who actually
did the work,
particularly, the--well,
anyway, my
colleagues--particularly the
toxicology technicians
and the animal care and the
laboratory assistants
who certainly did 99 percent
of this work, the ILS
Histology Department for the
H & E stained liver
sections, Dr. Robert
Maronpot at NIEHS, who read
the liver sections, Julie
Foley at NIEHS, who
helped with the cell
proliferation studies, and Dr.
Tom Goldsworthy.
Questions, please?
Questions
of Clarification
87
DR. MILLER: Dr. McBride.
DR. McBRIDE: I have two questions.
Firstly, is there any data
in the mice that is age
related? Secondly, if I am remembering right, you
had the only slide that
showed any changes at or
below 2 mg/kg dose was the
one slide on
cytotoxicity, I forget how
that was measured, and
if I am understanding you
right, that was
reversible at least in time.
DR. MOSER: That was in the 13-week study,
so let me see if we can find
that data. Do you
know, was that in the
13-week?
DR. McBRIDE: Yes, at the 13-week.
Although it was reversible,
it might still be of
import because, of course,
as we are looking for
any change, we are looking
for the lowest dose,
especially in humans where
there may be multiple
factors that affect risk.
In other words,
was this the only finding
that you found at 2 or lower
mg/kg?
DR. MOSER: I think that we had some cell
proliferation at 3 weeks in
this 13-week study, so
88
there was a significant increase at 2 weeks at 2
mg/kg at 3 weeks, and that
is the only significant
finding that we had.
DR. McBRIDE: But on your other slide, it
was a 0.5 mg/kg, the one
before that.
DR. MOSER: Okay, and I think what it was
there, it's a statistical
thing, we only had 10
animals per group, and we
had 2 animals that did
show some evidence of cytotoxicity. These slides
were read blind. It is not a significant increase,
but there is something.
DR. McBRIDE: And the question of age of
mice?
DR. MOSER: Age of mice. All the
short-term studies that we
did, the mice were 6 to
8 weeks old when we started,
and that is because
the liver continues to
divide and is really not
mature until about 10 weeks
of age, so we tried to
make sure that all of our
studies were done the
same, be they the short term
or the long term.
So, that our
short-term studies and
long-term studies, they all
started exposure at the
89
same age. It is just that with your 2-year
studies, of course, we went out to the end.
DR. MILLER: Dr. Gray.
DR. GRAY: I think something that we want
to try and learn about here
that is really
important for thinking about this food situation is
something you touched on in
one of your last
slides, and that is this
question of dose rate.
Is there any other
data to help us
understand that, because as
you mentioned, other
compounds that are thought
to act in this way show
a strong dose rate effect.
For example, chloroform
gives you very similar mouse
liver carcinogenesis
by gavage.
Ninety percent,
100 percent response, you
give the same dose in
drinking water over the
course of the day, no tumors
at all.
DR. MOSER:
Right.
DR. GRAY: And if dose rate is an
important factor here, that
is something we need to
know because that is a big
difference between our
animal studies here and the way in which people are
90
likely to be exposed.
So, I mean I don't
know if there is
something in the literature you can help us
understand, or if it is
something that we need to
think about as a study going
forward is
understanding whether there
is a strong dose rate
effect for liver tumors and
the other tumors that
are out there.
DR. MOSER: Let me say, and that is why I
put it up there, chloroform
has a mechanism of
inducing liver tumors that appears to be very
similar to that of
furan. If you give chloroform
by gavage, the same way we
gave the furan, you will
get liver tumors. You give them the very same dose
in the water, you do not get
liver or kidney
tumors.
So, that indicates
that maybe small
amounts over the course of
time doesn't have the
same effect as just one huge
dose, and particularly
maybe first thing in the
morning. They are
nocturnal, you know, they
move, they do things at
night. So, who knows? But that is a very, very
91
important thing.
DR. GRAY: And at this point, there really
isn't anything in the
literature to help us on the
furan front on this?
DR. MOSER: I think that Greg Kadaras [ph]
has done a little bit of
work, and I think it has
been inhalation, and I will
have to check on that,
but he has done work that I believe has been by a
mechanism other than gavage.
DR. MILLER: Dr. Krinsky.
DR. KRINSKY: Thank you for the nice
cancer cell biology
review. You used the term
"threshold" and
"dose dependent." Those are
not
identical, and I think that
is important in terms
of human consumption,
because if, in fact, your
data indicates that there is a threshold level
prior to seeing toxicity,
that may have very
important implications as
far as human consumption
is concerned.
DR. MOSER:
I would agree. The idea of
the threshold is that there
is, from my definition,
okay, in this study, is
there is a dose below which
92
you really don't see the
cytotoxicity, you don't
see the compensatory cell
proliferation, and you
don't see the liver tumors,
as compared to dose
response, which means, you
know, a low dose you get
a low response, medium dose,
medium, high dose,
high response.
DR. KRINSKY: And the mechanism for the
threshold?
DR. MOSER: What we would have to say is
that whether it's a matter
of intoxication, you
know, that there is just so
many mixed oxidase
function enzymes to produce
the toxic metabolite,
or there is a detoxification mechanism, you know,
it is believed that
glutathione is a way of
detoxifying the metabolite,
and there may well be,
and we know that is the
case, only so much
glutathione, so there is
only so much to help us
cart that toxic metabolite
out. Beyond that level,
you may see toxicity.
But the truth of
the matter is, when I
look at the literature, glutathione is the only
detoxification mechanism
they have looked at.
93
There may be others.
DR. MILLER: Dr. Russell.
DR. RUSSELL: Again, thank you for that
presentation. In thinking about populations of
humans that might be
susceptible to furan-induced
effects, the one that comes
to mind right away to
me is alcohol users, because
it is such a potent
stimulator of p450-2E1.
DR. MOSER: Exactly.
DR. RUSSELL: I
think that that ought to
be looked at in your model,
but in epidemiologic
models if this gets carried
on to humans, that this
really may be a population
that is much more
susceptible.
DR. MOSER: I think there was a study done
at CIIT, and it was a
short-term study in which
they induced the cytochrome
p450-2E1 by exposing
the animals to acetone, it was.
I don't think it
was the alcohol should have
done the same thing.
DR. RUSSELL: Yes.
DR. MOSER: So, you have these higher
levels of the enzyme that is
producing the toxic
94
metabolite, and we also know
that certainly alcohol
consumption is a
prerequisite to certain kinds of
liver damage and ever
certain kinds of liver
cancer, so that is a very
good point, and I
wholeheartedly agree. Thank you.
DR. MILLER: Dr. Callery.
DR. CALLERY: Let me probe that 2E1 a
little further. I want to know if you know that
the 2E1 in mice is the same
as the human 2E1 is one
question, and then another
is, I am probing my own
memory here, do you know
Carlson's work at Purdue
on styrene?
DR. MOSER: No, I am sorry, I don't.
DR. CALLERY: I believe he has got a null
2E1 mouse.
DR. MOSER: Oh, does he?
DR. CALLERY: Where the styrene was still
converted to styrene oxide
and had the same
viability for potential
carcinogenicity.
DR. MOSER: I think that's interesting
because it's like everything
else, you know, we
have looked at the 2E1. There may well be other
95
means of intoxication, we
just haven't looked at
them.
DR. CALLERY: Or detoxification.
DR. MOSER: Exactly.
DR. CALLERY: The other is I am trying to
relate the mouse to the
human, and especially in
the glutathione
concentrations and such, and the
redox activity in the
glutathione system. I don't
know how that relates to the
human.
DR. MOSER: I don't know either. Does
anybody know if the
glutathione levels are
comparable in mice and in
humans, or in the liver
anyway? I am sorry, I don't know.
DR. CALLERY: Then, I guess the last one
is you had mentioned that
you were at 2 mg/kg and
we have an estimation that
the human exposure might
be 1,000-fold less. Does
that have any meaning to
you?
DR. MOSER: Well, there is species
extrapolation, as we all
know, is extremely
difficult. Not only that, we have got a tissue
extrapolation here, you
know, that we are not
96
necessarily talking about, a
high incidence of
liver cancer in this
country, not to say that it is
not important, and most of
the liver cancer that we
see in this country we
believe to be more
associated with hepatitis and alcohol consumption.
So, does that mean
that I think that those
levels are safer? Not absolutely at all. It does
appear that the mouse is
more sensitive to liver
tumors than some of our
other models. Actually, a
better question is well,
what about the
cholangiocarcinomas. I mean they saw almost a 90
percent incidence at 2 mg/kg
in your NTP bioassay.
Is that relevant?
Well, here, we
don't know, at what dose do
you continue to get these
cholangiocarcinomas. As
I look at the literature,
and I am not an expert on
that by any means, it does
appear that the rat is
more sensitive to at least
cholangiocarcinomas than
are mice or humans, that in
all the reading I have
done in the last week or so
trying to prepare for
this, there is only one
study in which there was an
increased incidence of
cholangiocarcinomas in mice,
97
and that was with PCBs,
polychlorinated biphenyls,
and they were on some sort
of a restrictive diet,
and the incidence was not as
high as what you are
seeing in your rat.
So, again, we go
back to the species is
extrapolation, is that data
in rats relevant to
humans at that dose. I wish I knew.
DR. MILLER: Dr. Chesney.
DR. CHESNEY: You just mentioned
hepatitis, and I was
thinking that another human
population that might be at
risk for furan are
patients with hepatitis B
and hepatitis C, and
there is an animal model for
hepatitis B, and I am
blocking on the
species. I think it might be the
prairie dog, but I am
probably wrong about that.
DR. MOSER: Is it the woodchuck?
DR. CHESNEY: It's the woodchuck, that's
right. Thank you.
DR. MOSER: Don't ask me how I knew that.
That just came out of some
deep recesses.
DR. MILLER: I am going to call for a
break. Can we be back here in 10 minutes.
98
[Break.]
Public
Comments
DR. MILLER: The FDA received only one
request for public comment,
that by the National
Food Processors
Association. It was to be
delivered by Dr. Richard
Jarman.
Dr. Jarman has
said that in the interest
of facilitating the
discussion, he submitted a
statement which he intended
to read and which you
have all received a copy of,
and he is prepared to
allow the statement to stand
in lieu of having to
make a presentation.
So, the statement
will be incorporated in
the record.
Summary and
Charge to the Committee
DR. MILLER: Now we come to the nitty
gritty. Before we begin our
discussions, Dr. Terry
Troxell of the FDA will
summarize and re-present
the charge and reading of
the questions, and then
we will proceed with our
discussions.
DR. TROXELL: Thank you.
My name is Terry
Troxell, Director, Office of Plant and Dairy Foods.
99
I don't want to
take much of your time. I
just want to recapitulate a
little bit to
facilitate your
discussion. The main points here
are the actions we take and
what are the data
needs, the charge, and the
questions.
As we have said,
we have developed the
method. The method was posted on the web site. We
are going to be doing a
round robin, so we should
sort out any differences in
levels being observed.
We did an exploratory survey, more than
160 foods were in our first
round, and with 40 more
since we published a notice
in the Federal
Register, and 30 from
Canada. We are now at 230
foods, and we will be testing a broader range of
foods.
The preliminary
exposure assessment was
done. We utilized the first 160 samples,
obviously, because things
are moving so fast, we
were not able to incorporate
all the data that we
pulled recently.
We also obviously
did our call for data
and then we have established
international
100
interactions. We provided Canada with our method,
and they very quickly
developed additional methods,
similar, so that we could generate a lot of data
together, and we also
coordinated, so that we could
minimize duplication of
effort, so that we can
maximize the results at this
point.
The other thing you should be aware of is
that the EU has a heat tox
project, which is to
look at investigating
thermally processed induced
toxins in foods, and they
are going to incorporate
furan in that process.
So, again, as with
acrylamide, we are
trying to maximize our
collaborations to try to
zero in on the problem as
soon as possible.
Some future
actions, of course, we still
have another 30 days to go
on our data call, and
then we will evaluate that
data, the whole group of
data. We will take the tox studies to our Cancer
Assessment Committee or
CFSAN's internal expert
group to have a look at the
overall picture and to
help us decide where to go
from there.
We also want to
develop an action plan to
101
provide guidance, not only
for FDA, but also in our
broader collaboration
efforts, so that we can
adequately assess the risk,
and, of course, to
serve as a basis for risk
management.
Data needs. Or course, we need a broader
range of foods in which
furan occurs. We need to
know the levels of furan in
these foods, and then,
of course, the formation and
occurrence in
home-prepared foods.
We have been
working on a hypothesis that
pretty much if you cook the food in a hermetically
sealed container, like a can
or jar, whatever is
formed in there is trapped
and can't escape,
whereas, other foods, such
as potato chips, which
are produced in an open
line, or cereal, or so on,
that a significant amount of
degassing would occur
or volatilization would
occur either in the
processing environment or
subsequent through
diffusion.
So, then, it gets
to the question of what
happens in the home
environment, what happens in
the retail environment,
where you might generate
102
some furan, and it does not
have time for
dissipation, so, yes, we do
need to flesh out what
is happening in the home
environment, which also
would be relevant to a
retail environment.
The other
consideration we need to bring
into this is other
environmental sources of
exposure to furan, such as
from smoking, there is a
range of possible areas.
We have here
possible mechanisms of furan
formation. In addition to possible mechanisms,
what we would be most
interested is the principal
mechanism of formation
during standard process in
home cooking.
We also have
variables that enhance or
mitigate furan formation,
stability, or dissipation
of furan in foods. Again, that goes to the
dissipation over time, for
example, and the
stabilization with fats in
the food, effects of
post-production practice on
furan levels.
Then, we have
quite a few areas of
toxicological needs,
mechanism of furan and
toxicity, mutagenicity, and
carcinogenicity, the
103
reproductive and
developmental toxicology of furan.
We have basically zero on
that to my knowledge.
The metabolism of furan in
vivo including
characterization of reactive furan metabolites.
The diversity of
furan pharmacokinetics in
humans or the alteration of
furan metabolism as a
result of dietary, medical,
or environmental
interactions.
Data on whether
sub-cytotoxic furan doses
produce any adverse effects,
such as a change in
enzyme activities or ATP
levels.
The effects of furan doses lower than
those used in the NTP
study: to establish a
dose-response curve for
various tox endpoints; to
determine whether furan
toxicity including
carcinogenicity is a threshold dependent event; and
to determine whether
carcinogenic activity is
secondary to hepatotoxic
effects.
Still more. The mutagenicity of furan in
the TA100 strain in the Ames test. It was weakly
positive in one study, but
negative in all Ames
strains in the NTP
study. The behavior of furan in
104
other in vivo assays for
mutagenicity or toxicity.
Then, that brings
us to the charge, which
is in Tab 2 of your
notebook. That is the Food
Advisory Committee and Contaminants and Natural
Toxicants Subcommittee are
being asked to provide
input on the data that would
be helpful for further
evaluation of potential
risks posed by the presence
of furan in food.
Then, the question
which I will leave up
here to help
discussion. Taking into consideration
the data needs already
identified in the Federal
Register notice requesting
data on furan, and the
presentations at this
meeting, are there any
additional data that are
needed to fully assess the
risk of furan in food?
The data needs we identified are fairly
broad. Are there still gaps? What are the
important missing data for
assessing the human
health impact from furan in
food? Since there are
studies available in some of
the areas, such as
mutagenicity, which areas
need particular fleshing
out and in what ways?
105
I guess this is
what to me is encapsulated
in the broad question. Finally, I want to thank
you very much for your
critical input here. We are
at a very early stage in
this process in trying to
get our arms around this
issue, and it is very
important to have your
thoughts to help us do the
right set of work and
develop the action plan, to
guide our efforts for the future.
Thank you very
much and I can try to
answer questions that may be
lingering and, if not,
we can have our experts
answer those I cannot
before you start your discussion.
Questions
of Clarification
DR. DWYER: Dr. Troxell, a couple of
months ago, i think it was,
or maybe longer, we
discussed acrylamide in food, and I wonder if there
is a sort of a large plan to
look at all the
heat-formed compounds that
seem to be of concern,
and is this part of it, or
how is that being
handled, the big picture?
DR. TROXELL: We have no comprehensive
program to look at
them. The EU has this heat tox
106
program that they put a
fairly large sum of money
in to work on, on thermally
generated toxins. We
are collaborating with them,
I mean interacting
and, as I said, we have
contributed a new one to
their effort.
DR. ACHOLONU: We are told that you have
checked different kinds of
foodstuffs so far, and
you have plans to do
more. Have you been checking
these randomly, or do you
have a special pattern
that you are using to select
the foodstuffs to
check for furan?
DR. TROXELL: Well, again, the theory we
used for several fold. Those foods we expected to
contain furan, such as the
canned and jarred foods,
and also even if we expect
at the levels to be on
the low end, we also wanted
to check the foods that
were major contributors to
the diet, such as the
apple juice for the
children.
So, yes, we have a
strategy, and as with
acrylamide, we will focus in
on those foods which
seem to be the major
contributors and look at those
intensely, but also expand
more broadly to make
107
sure we haven't missed anything, and over time, we
have picked up a few
additional items that have
contribute.
So, we have to
start at the first base and
we will keep digging in
until we kind of flesh it
out more completely, and
with our collaboration
with Canada and hopefully
the EU, hopefully, we
will get to fairly
comprehensive understanding of
the foods that contribute significantly to the
exposure.
DR. MILLER: Dr. Waslien.
DR. WASLIEN: The total diet study
analyzes now for toxicant
suppression in food as
well as vitamins, and I
would think that it might
be worth investigating to
see about collaboration
with that process, too, just
to get a better mix of
foods, say, go out and buy
it, you know, a
systemized fashion, and you
can get an overall view
of exposure in the U.S.
diet, and it may identify
at least for one shot,
groups of foods, maybe that
way more easily.
DR. MILLER: Dr. Lee.
108
DR. LEE: I was just wondering, I guess
furan has been looked at by flavor chemists because
it is part of the flavor,
taste of food. Does it
actually have a role in food
acceptance or it is
just an incidental compound
that has no measurable
positive impact on food?
DR. TROXELL: I can't answer that
precisely. I know the class of foods, the class of
chemicals is known as the
furans of various
derivatives.
Some of those would have a role
in
flavor chemistry. I don't know that furan per se
has a role in flavor
chemistry. Certainly, once
you start getting into that
class and you get side
reactions and decomposition,
and so on, you are
going to end up with tiny
amounts of furan in foods
as we have found, and with
the new analytical
technology, we are now able
to tease out very
precisely what couldn't
easily be seen back in '74,
for example.
DR. MILLER: Dr. Lund.
DR. LUND: Relative to occurrence and
exposure, you mentioned specifically home-prepared
109
foods. Are you also going to be looking at food
service preparations in
restaurants?
DR. TROXELL: This is a good comment, and
I think many of the
approaches used in restaurants
are the same approaches used
in the home. I mean we
have to look at microwaving,
and so on, to see what
generates food, what
generates furan, you know, at
levels that don't dissipate
by the time the
consumer ingests the food.
It is the same
problem, of course, with
the total diet study. We have worked on volatile
organics and I don't know
what protocols we used
there, but we have to be
careful that, you know,
those foods are analyzed ready to eat, but by the
time, you know, they are
prepared by a church
group, and if they are not
specially processed
after they are cooked, we
could lose whatever furan
was formed, and it will not
be as consumed, so we
need to be very careful that
if we do such a study,
we end up with something
that mimics as consumed.
DR. MILLER: Dr. Nelson.
DR. NELSON: I just wanted to follow up on
110
Dr. Lee's question about the
flavors. I don't
believe furan is itself a flavor compound, but
furanial is and furferal
[ph] is, and I believe
FEMA, the Flavor and Extract
Manufacturers
Association, has done a
toxicological review, that
they are pretty well clear.
DR. MILLER: Jean.
MS. HALLORAN: Earlier, you had a few
cases where you heated the
canned foods and had
some interesting
results. Are you going to do any
more with the canned foods
to attempt to mimic
preparation, normal
preparation situations?
DR. TROXELL: Yes, I think whether it be
the canned foods, whether it
be a soup that is put
in the microwave and heated
to see if that
increases the levels or not,
of other foods that
are cooked that might
generate from the get-go
whether we might have furan in an oven-baked food,
I think we probably have to
check some of those
things out just to cover the
territory, so we
understand the dimensions of
the exposure.
DR. MILLER: Dr. McBride.
111
DR. McBRIDE: A couple of questions. Do
we know anything in the animals
about serum levels?
I am not even sure that
serum levels are valid
because the boiling point is
below body
temperature, and probably
first pass to the lungs,
it is pretty well out of
there, but do we know
anything about serum levels
in animals?
DR. MOSER: No.
DR. McBRIDE: I don't know whether that is
worth pursuing or not. Also, do we know anything
about furan exposure
industrially in humans?
DR. TROXELL: I don't know anything about
it. Certainly, there would be a component of
interest, but it would
probably be a small portion
of the population, and if
you are thinking of using
such a group, for example,
to look at epidemiology
to see if there is an
increase of tumors that way,
such as was done with acrylamide, that certainly is
a question that could be
asked.
I do believe on
your other question that
there is some comparative
metabolism studies in
different animals on furan, although I don't know
112
that there is serum levels,
but there certainly is
as compared to metabolism, I
believe.
DR. McBRIDE: But it would probably be the
two issues, you know,
whatever wasn't metabolized
in the liver may or may not
stick around in serum,
probably wouldn't by the
boiling point, but I am
not sure.
DR. TROXELL: I think it is cleared fairly
fast, I think the half-life
is fairly short.
DR. McBRIDE: Another, at-risk population
might be smokers.
DR. TROXELL: Absolutely.
DR. McBRIDE: Houses with lots of smokers,
that sort of thing.
DR. MILLER: Dr. Chesney.
DR. CHESNEY: I have one specific question
and then I have a whole list
of suggestions. Is it
appropriate to do that now
or did you want to wait?
DR. MILLER:
Why don't we wait until we
finish with Dr. Troxell.
DR. CHESNEY: The more specific
suggestion, people are
mentioning other things to
113
test. I wondered if it would be worth testing
intravenous and parenteral
preparations that are
given to humans because a
lot of them have lipid in
them, are given continuously
for long periods of
time, and they are often
warmed or heated before
they are given.
DR. TROXELL: You mean intravenous or tube
feeding?
DR. CHESNEY: Both.
The tube fed ones do
come in cans, and the
intravenous ones obviously--
DR. TROXELL: There is also a time factor.
To put it in context, there is a time factor here
in that we are talking about
generally chronic
effects, so if you are
talking about a short-term
exposure, even though we may
be particularly
concerned because it is
higher or a worse case
exposure, the effects we are
talking about
generally are chronic
exposures, so we should put
them in our equation what we
look at.
DR. CHESNEY: I understand, but we have
children, for example, who
are on parenteral
preparations for years
because they have had their
114
GI tracts removed, or many
people are fed enterally
for other reasons
continuously for years and years.
DR. TROXELL: It would be good to check.
DR. MILLER:
Dr. Downer.
DR. DOWNER: I am just going back to Dr.
McBride's question about
environmental exposure.
We did mention cigarettes,
but also I read in one
of the studies that exposure
or people who are
bakers, who are expose to
baked bread, that was
also an environmental
exposure risk, so perhaps we
may also want to look at
individuals who are in the
baking industry to see if
perhaps there is some
consideration there.
DR. MILLER: Dr. Chin.
DR. CHIN: I just want to actually go back
to something that Dr. Beru mentioned. Just for
point of clarification, I
thought that he said that
when FDA did the initial
assessment of the risk,
that you took the work that
was done by the
National Academy of Sciences
and NASA, and you came
up with a NOEL of 80 mcg/kg
per day, I believe.
DR. TROXELL: National Academy came up
115
with number.
Committee
Discussion and Recommendations
DR. MILLER: If there are no more direct
questions, he will be here
in case the issues come
up again.
So, now the time
comes for us to start
making some recommendations
for studies that ought
to be done, that have not
been thought of by the
agency.
The question is
what can we add to their
action plan that would be
useful. I am sure you
all have your favorite
lists. A number of them
have already come up in our discussion. The impact
of development on metabolism
of furans, I think
was one of the earlier ones,
and I think that is a
very important issue,
particularly given the fact
that there is a substantial
part of the exposure is
in infants, and so we need
to know better whether
or not there is a difference
in the sensitivity of
infants or elderly, for that
matter.
The question of
dose rate, all the
experiments that have been
done so far have been
116
done with daily bolus and there is some suggestion
that there may be a
difference between bolus
exposure and continuous
exposure, and that becomes
very important from a
methodological point of view,
as well as from the point of
view of trying to
interpret the potential
hazards associated with
furan exposure.
Another
interesting one that came up in
the first part of the discussion is the question of
glutathione, is glutathione
the biological
detoxification step, the
principal biological
detoxification step for
furans, and if it is, can
you associate things such as
the cytotoxicity of
furans with the regulation
of the glutathione.
That it seems to me needs to
be done.
The question of
food service has come up
quite a bit. I am not so sure it's true, Terry,
that the processes used in
food service,
preparation of food are
identical to those used in
the home. They are often cooked at higher
temperatures and maybe for
shorter times, so I
think it would be worthwhile
to take that into
117
account in determining your
sampling program.
The other thing
that occurred to me, and I
may have missed it, but I
didn't see anything on
mother's milk, how much of
mother's milk, how much
of furan or of the metabolites, potentially toxic
metabolites of furan show up
in mother's milk.
I think, Dr.
Chesney, you said you had a
long list.
DR. CHESNEY: Is it my turn?
DR. MILLER: It's your turn.
DR. CHESNEY: Thank you very much.
Let me just start
with a general overview.
As you know, we have a very
yuppified generation of
young parents out there, and
I think as soon as
they hear more about this,
they are going to be
quite active and involved,
and I know you have
anticipated that, but the first thing I wanted to
mention is very simple, and
that is that it might
be interesting to look at
levels of furan in
home-prepared baby food.
This was very much in 20 or 25 years
ago,
and it was a lot of work,
and so I didn't last very
118
long with that, but that is
certainly something
that you would be able to
give a very quick answer
to people if they had
questions about if I made my
baby food at home, and
didn't heat it, would my
infant be better off.
So, my other
issues, obviously, as
pediatricians, we think very
much developmentally.
We think about the
mother-fetus diad, and then the
newborn who is very immature
in many respects, and
then the infant and
ultimately the child.
So, in terms of we
wonder about tissue
penetration, tissue
concentration, and impaired
metabolism and excretion
depending on the age. So,
starting with the maternal
fetal model, I think
maybe using animal models of
pregnant mice or rats,
and then newly delivered
mice or rats to look at
issues of transmission, is there enhanced
transmission across the
placenta, is the placenta
particularly concentrated in
terms of furan or none
at all.
And then I also
had breast milk on my
list, is a very important
issue, and somehow it may
119
be even clinically in humans
ultimately tying
levels in breast milk to
levels that the mother
ingested in the recent past.
And then turning
to the newborn, we have
seen the levels in formula
and infant food, but the
newborn GI tract is a
relatively porous organ, and
i don't remember enough of
my GI pathophysiology to
remember how long that goes
on, but is there
enhanced furan uptake in the
first few weeks or
month of life, and does it
concentrate in other
tissues and/or pass into
other tissues.
We have talked
about the liver and the
background materials we were
given, talked about
the kidney, but obviously,
again in terms of
development, as
pediatricians, we are always very
worried about the
brain. Could studies be done in
fetal and infant animals to
show whether the furan
is penetrating the brain
because that is a question
that will come up very
quickly when more and more
people learn about this.
Questions about infant PK studies of
furan, again maybe before
and after ingestion. The
120
issue of home preparations
and finally sick
infants. We have a lot of children who come in for
fairly acute self-limited
illnesses that do develop
liver damage, transient
liver damage, and then we
have large populations of
premature infants and ill
infants who spend prolonged
periods of time in the
hospital, who often are fed
with these intravenous
or nasogastric preparations,
and they often also
have underlying liver disease in part because they
get the intravenous
parenteral preparations.
So, if there were
any question about
significant furan levels and
what we are giving
them on top of the fact that they already have
cytotoxic liver damage in
many cases depending on
the underlying disease, I
think that would be
important to know.
That is my list for the moment.
DR. MILLER: Good.
Thank you very much.
DR. KRINSKY: I just want to point out
that once you move from the
food into the animal or
the human, that furan is not the only thing that
should be analyzed because
furan is not the active
121
component, furan is
metabolized, and I think we
have to have information
about what the metabolites
are, what the active
metabolites is, and whether,
in fact, this can be assayed
in tissues, in fluids,
or anything of that nature, but not just the furan.
DR. MILLER: Dr. McBride.
DR. McBRIDE: I think it is a good
suggestion to look at it in
breast milk, and again,
one might want to look at it in the at-risk group,
smokers, for instance,
versus non-smokers or
something like that.
The second
suggestion is in looking for
mutagenicity, one might want
to do
second-generation studies in
the rats especially in
the females.
DR. MILLER: That is a good idea.
Dr. Callery.
DR. CALLERY:
About the metabolism and
follow-up on what we just
heard about the metabolic
activation, I am wondering
if there isn't the use
of the Ames test, not just
for furan, but also in
the presence of human liver
microsomes, such that
122
it would have a
bioactivation potential to screen
for mutagenicity.
The comment about
glutathione as a
detoxification pathway, the
compound that is in the
literature that is the
potential mutagen is a
sis-buten-dialdehyde [ph],
which I believe has been
shown to be mutagenic in
some system.
But the way that
that compound may also be
detoxified in addition to
glutathione or other
sulfhydryl compounds is by
oxidation of the
aldehyde and further
conjugation of those products.
So, beyond the cytochrome
p450s are the soluble
enzymes, probably the
aldehyde dehydrogenase or
aldehyde oxidase that would certainly want to be
looked at.
The comment about
the infant and aged, in
their metabolism, if this is
a metabolically
activated compound, it might
be advantageous to the
newborn not to have 2E1 and
another p450 isoforms
might be to their benefit.
So, that might beg
the question of whether
you want to do any even--I
don't know if there is
123
genotyping, pharmacogenomic
issues about whether
2E1 is available and in
different population sets
or if you wanted to actually
consider relating 2E1
concentration to potential
for mutagenicity.
I had another
comment that was about the
broader collaborations that
we have been hearing
about and especially since
one of the issue here is
the mechanistic aspect of
how this substance might
be bioactivated, is the
possibility of working with
NIH to have the National
Institutes of Health
consider an RFA on the
mechanisms of this, and then
when you look to the
comments of the workplace
exposure to furan might also
involve a
collaborative association
with the EPA.
DR. MILLER: Dr. Gray.
DR. GRAY: Thank you.
I have just got two
areas that I would like to
comment on. I think
that there is really no way
that we can continue in
a situation where we haven't
done reproductive and
developmental tox on this
material, and it just
seems to me that that is one
of the things that
should be in an action plan pretty quickly, at
124
least getting some feel for
this.
Some other
compounds that act like it, it
is probably not something
where there is a serious
concern there, but it is
just the kind of
information I think that
needs to be developed in a
fairly short time.
The other thing I
wanted to do is to
encourage the work on the
mechanisms of formation.
I think that is a really
important thing, and I
think it is important for a
reason that was
actually raised by Jim
Coglin in his letter that he
submitted.
This already looks
like it is in. I think
the estimate that we just
saw it's in about 20
percent of the food supply now, and that's not
consumption weighted, but 20
percent of the food
supply, it may end up in 30
percent or 40 percent.
We are not going to be able
to avoid it.
Then, we are going
to have to start
thinking about ways in which
we will try to manage
it, and I think it will be
important about
understanding the mechanism
is by in managing that,
125
we want to make sure that we
are not making risks
worse, that some of the
things we have talked
about, like pasteurization, have their own real
benefits that we have to
understand.
So, if we can
understand the mechanisms,
perhaps we can design ways
to control it if that is
necessary, but we can at least keep in mind the
tradeoffs that we might
face. So, this is just I
think a plea to continue
working the great work
that has been done in
Canada, work that is being
done in FDA, to try and move
along the mechanisms,
so we don't find ourselves
making things worse by
trying to address this
problem.
DR. MILLER: Thank you.
I think ideas like that were incorporated
in the plan. I say that only because it is
important to reiterate it
because I think it is a
basic thing. The issue for these adventitious
contaminants that are
natural products, the only
thing you can do is mitigate
them. You can't bann
the food.
DR. GRAY: I don't want to give up my
126
coffee.
DR. MILLER: That's always a personal
thing.
Dr. Downer.
DR. DOWNER: I
agree with what my
colleagues have said, I just
wanted to add a little
bit by saying we really need
to do some more
comprehensive data on the
furan that is found in
foods and beverages, and perhaps using the U.S.
data tapes or some of the
NHANES data or some other
database, so that we can get
a better perspective
of the different kinds of
foods and groups of foods
in particular and the furan
levels in them.
Also, I think it
would be good if we found
that we should establish an
acceptable level. If
furan level is low, then, we
might not need to
implement a risk management
protocol, but if it is
higher than the level that
was established, then,
we will want to do some
interventions then.
I go back to what you said, Dr.
Miller. I
concur because we really
don't prepare foods at
home as we do in a
restaurant. We haven't look at
127
condiments, for
example. We don't know the impact
of that. It may be small, but it may be
significant.
So, I think it
would be prudent for us if
we look to see if there are any risks in food
preparation and
packaging. We may want to look at
home prepared, restaurant
prepared, as well as
pre-packaged foods to see
what levels may be there,
as well.
DR. MILLER: Dr. Lund.
DR. LUND: Just to follow up with regard
to the types of processes
that ought to be looked
at. It would be good to look at a couple of the
newer processes. You might not expect to see much
furan formation in high
pressure processing, for
example, but it is certainly
an alternative for
thermal processing in some cases, and at some point
needs to be looked at among
other processes, as
well.
DR. MILLER: Dr. Dwyer.
DR. DWYER: I think I share other people's
concern that a wide variety
of possible suspects
128
among foods be look at, not
just the ones that have
been looked at. I am still puzzle by this business
of heat formed compounds
occurring together. Last
year, we heard that potato
chips were very high in
acrylamide.
So, is it because all the acrylamide is
taking up the main line of
reaction, who knows.
The second thing
I am concerned about is
the whole issue of risk and
the sensitivities that
have been mentioned. I believe Dr. Russell
mentioned alcohol. Dr. Krinsky mentioned I think
hepatitis B and C, smokers
have been mentioned.
Coffee has been mentioned,
but only in a positive
context, it might have some
effects that would be
worth looking at, and then I
wonder about common
OTC, particularly OTC, but
also perhaps prescribed
drugs that might affect
those same systems as being
important to at least take a
look at.
The final area has
to do with mechanisms
and metabolism, the issue of
dose rate of
compounds, is there a
threshold versus the dose
response business, the issue
of getting common
129
methodologies so we don't
overduplicate all seem to
be important.
DR. MILLER: Thank you.
Dr. Lee.
DR. LEE: I suppose if the FDA could wave
its magic regulatory wand
and eliminate all of this
compound in food effective
tomorrow, but the
question needs to be asked,
is the human condition
going to be substantially
improved, and I just
don't know if you have got
there yet.
Particularly, I
would like to see what the
relative exposure is to
humans from other sources
of furan. I don't have a
good feel for that, is
food really the problem, or
is it just that we are
sensitive to it because it
is showing up in foods
and things that we think
ought to be absolutely
pure.
I think that is really
a very subjective
judgment whether or not the
human condition is
improved by elimination of
the compound, but we
need the data on where the
problems lie outside of
the food system.
130
DR. MILLER: That's a good point, but the
problem is that you can't
answer that question
until you know all this
other stuff, and I think in
the end, that is what the
goal ought to be. Or
course, there are others, it
is going to depend
upon the agency's
decisionmaking, but that should
be the primary goal.
Dr. Chin.
DR. CHIN: I guess one area that I guess
gets back to the basics in
terms of measuring
furan, and I know that a lot
of work has been done
already in terms of
validating the methodology, but
as we got further into this
and especially as
people make decisions or
make assessments, I think
we need to probably do more
work on the
methodology, you know, more
collaborative study,
maybe develop some type of
an official or
standardized methodology.
We also probably
need to make absolutely
sure that we are neither
producing the furan during
the analysis, nor are we
missing the furan in
analysis. So, I think those issues still need to
131
be looked at as we go
forward.
DR. MILLER: Dr. Acholonu.
DR. ACHOLONU: We are told that FDA has
found measurable furan in
jarred baby foods, in
canned infant foods, in
canned adult foods,
emphasizing can and
jar. It may be necessary to
find out if the jars and the
cans have anything to
do with the concentration of furan in the food.
That is a
suggestion I would like to make.
DR. MILLER: The situation that has to be
looked at, and the situation
like this is a
risk-risk situation, what
are the risks of doing
something versus the risks
of not doing something.
In other words, if you give
up reprocessing of
foods, what is the hazard
associated with that,
too? I think that is the question that you were
asking.
DR. ACHOLONU: The can itself, the can,
the jar. Does the can have
anything to do with the
content?
DR. MILLER: Packaging.
DR. ACHOLONU: Yes.
132
DR. MILLER: Your question is the
packaging.
DR. ACHOLONU: And this you can do by
comparing, as they test
different kinds of foods,
get the ones in jars and
cans, and the ones that
are not in jars and cans,
and compare them, and
find out if there is any
difference, and then use
that to make some
extrapolation.
DR. MILLER: That issue has arisen several
times concerning the
packaging. It is not the only
thing that you have to worry
about, there are other
kinds of packaging that
might be a problem.
DR. MILLER: Dr. Chesney.
DR. CHESNEY: I haven't heard anything
about serum levels of furan
or its metabolites. Do
we know if it is normally
detectable in normal
humans, or has anyone looked
for furan levels in
serum, or the metabolites?
DR. MOSER: I think that there has been a
PD/PK model,
pharmacodynamic, pharmacokinetically
based model, in which they
predicted serum levels,
but I am not sure that they
actually quantified
133
them.
DR. CHESNEY: So, they have never actually
drawn blood and tested it in
humans.
DR. MOSER: Not that I know of.
DR. CHESNEY: I think Dr. Lee's point is
very important, that this
may be nothing, this may
be a nothing issue and we
have to be very careful
not to overreact, but
certainly, as I mentioned,
when the yuppie population
hears that it is in
infant formula, they are going to become very
alarmed, and I think it
might be nice to have some
sort of very--if the
methodology is out there for
measuring normal furan
levels and serum, and just
doing a very simple PK/PD
study based on ingestion
of high furan foods and low
furan foods. That
seems like it would be fairy
straightforward.
DR. MILLER: I would only modify that by
saying that whatever the
principal toxic
metabolites are may be more
important than looking
for furans.
DR. CHESNEY: I agree. I keep saying
furans, but furan or its metabolites or just its
134
metabolites.
DR. MILLER: Good.
Dr. Krinsky.
DR. KRINSKY: I
just want to emphasize the
potential nothing aspect of
what we are dealing
with, and since we don't
know, we don't know what
the levels are that might be
toxic, we don't know
whether we can achieve that
level with the diet.
There is so much that we
don't know about this that
that is why we have a series
of questions where
there are things that we want
to have done.
What concerns me
is that the FDA will
treat this in an appropriate
fashion. I must say
that I am very concerned
about the people sitting
behind us. I don't know how many of them are from
the press, but I am really
concerned about how the
press is going to interpret
what we are raising
here in terms of furan in
foods.
We don't know if
what we are looking at is
potentially harmful. We don't know if it is
harmful. We don't know if it is potentially
harmful, and yet I think
what we have been talking
about can be misinterpreted so easily that I would
135
like to censor any press
release that comes out
from behind us.
DR. DWYER:
Go the pentagon, this is the
wrong agency.
DR. MILLER: That temptation is never
fulfilled.
You are right, of
course, I mean this
committee was not put
together to consider that
issue, but nevertheless, I
don't see how you can
come to any conclusions
unless you do the
experiments to get the data
to see whether it's a
problem of not, and it may
turn out to be nothing,
but you have got to do the
experiments to find that
out. You just can't ignore it.
Dr. McBride.
DR. McBRIDE:
Along with that, we don't
want to spend a lot of the
agency's money looking
at something that may turn
out to be a non-entity.
Again, back to the
serum levels. It seems
to me the first place to
look is those rats that
got those high doses,
because if it isn't there,
chances of our finding it in
the human are small,
136
and, of course, looking at
the brain, a high lipid
organ, as well.
I was in my
wildest dreams trying to
figure out what groups of
kids would we go, and how
would we even approach the
mom, but there are a
group of kids who are
actually orange from eating
so many sweet potatoes out
of the jar, so if we
feel a need to go to humans, that might be one.
DR. MILLER: Dr. Chesney.
DR. CHESNEY: In response to Dr. Krinsky's
comment, I think, as we
said, this may turn out to
be nothing, but I really would like to commend the
FDA for making this public
so quickly in your
deliberations.
I mean you keep
coming back to the May 7th
on the web, and most of us go to the Federal
Register on a regular basis,
but you had it out
there immediately, and I
don't know how you could
do otherwise, and I think
that that is the most
important message.
We don't know what this means,
but we are letting you know
that we are looking at
it, and so I just wanted to
make that comment.
137
DR. MILLER: Thank you.
Any other
comments? Any other
suggestions?
DR. CHIN: I guess just to reiterate, it
seems to me that the most important piece of
information that we need is
to come to some closure
in terms of whether or not a
threshold exists and
what that threshold level
might be, and so either
the continuation of the work
that was reported by
Dr. Moser or something along
those lines, I think
it is very important because
that is really going
to guide us in terms of how
much more resources to
put into this issue.
DR. MILLER: To answer the question, I
think some kind of risk
assessment is going to have
to be made. It is not going to be a very good risk
assessment because they
don't have all of the data
that they are going to need,
but they need to have
some ballpark figure.
If I had to
personally mark a suggestion
concerning this, I would
make that my highest
priority, develop that data
that allows me to make
138
a risk assessment.
Also, I think from
a regulatory point of
view, I think if you do this
risk assessment, you
also should be doing risk
assessment about what
would happen if you weren't
able to process food
according to the
technologies that we have
available.
Dr. Waslien.
DR. WASLIEN: That would eliminate me for
the Atkins Diet, wouldn't it?
[Laughter.]
DR. WASLIEN: As part of that risk, I
think you said that once
mice or the rats were off
of the diet, that you saw
the disappearance of any
carcinogenic effect, so it
is not cumulative, so
it's purely a sort of short
duration or ongoing
exposure that has to be
present, or was that
documented enough?
DR. MOSER: There is also data that
demonstrates that one high
dose was able to produce
tumors two years down the
road. There was also a
stop group that got higher
doses than we gave them.
139
They got that for 13
weeks. Then, that exposure
was stopped, and they found
increased lesions as
compared to the group that
was continuously
exposed.
DR. WASLIEN: Then, concentration effects
are part of the metabolism
you have to look at,
too. Thank you.
DR. MILLER: Any other comments? If not,
that's very good. I am not going to even try to
summarize all of the very
good suggestions that
have been made. I wanted to keep them for the end
of the meeting, so that in
the preparation of the
report of the committee,
summary of the meeting,
from the transcript, all of
these would be in one
place and make it easier to identify these
recommendations to the
agency. For that, I thank
you.
The next step is
to develop a verbatim
transcript of the deliberations
of the committee,
and that will be made
available on the internet,
and then a summary document
of the committee's
deliberations will also be
prepared, and we will
140
share that with you
directly.
I have nothing
more to add except to thank
you all very much. I appreciate you remaining
focused and disciplined generally.
Terry, do you have
something to say?
DR. TROXELL: I just would like to say for
the Center for Food, Safety,
and Applied Nutrition,
and FDA, thank you for your
two days of close
attention and careful and
well thought out input,
and we know it is a
tremendous effort out of your
busy schedules to do this
for us, but it is
invaluable and thank you for
myself, Dr. Laura
Tarentino, and the rest of
FDA.
DR. MILLER: Thank you, Terry.
Hope you all make
your planes and I want
to thank you personally very
much for being a very
good committee.
We are adjourned.
[Whereupon, at
5:00 p.m., the hearing
adjourned.]
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