Health Consultation
(Exposure Investigation–Phase II)
(a.k.a.
June 11, 2003
|
Prepared by
U.S. Department of Health and Human Services Agency for Toxic Substances and Disease Registry Division of Health Assessment and Consultation |
Table of Contents
This exposure investigation examined individuals in the
The investigation focused on whether these individuals had been exposed
to
arsenic contamination in
their
yards. The
investigation was conducted from July through November
2002 and is the follow-up
to an earlier (March
2002) investigation.
Urine arsenic levels were tested in 40 individuals: 34
adults and six children aged
21 months to 15 years.
All of these individuals
were residents of 19 homes where the yards showed
elevated
soil arsenic levels,
or homes adjacent
to properties under remediation
for elevated soil arsenic levels.
During World War I,at a site known
as the American University Experimental Station in northwest During
research and training operations, .
chemical weapons
were detonated at several locations.
Lewisite (which contains arsenic) and mustard gas were among the chemical
warfare agents reportedly
tested. Chemical agents—including
hazardous substances, ordnance, and explosive waste—were
buried in the area. Long after the
Army vacated the former
Experimental Station
site, the
entire area
underwent extensive
development. Today it ishome to the
In January 1993, a contractor digging a utility trench
in the
U.S. Army Corps of Engineers (Corps) launched Operation
Safe Removal, extracting
some 141 ordnance items
including
suspected chemical munitions containing mustard gas and fuming sulfuric acid.
To identify other
potentially impacted areas,
the Corps
reviewed historical records and conducted extensive geophysical surveys with
electromagnetic instruments.
In addition, to characterize the extent and nature of chemical
contamination, the Corps collected
soil samples
in potentially affected areas.
Discovery and remedial efforts continue in
The Agency for Toxic Substances and Disease Registry (ATSDR) has been working with the following agencies and groups:
· The Department of the Army,
· the Army Corps of Engineers,
·
the
·
the District of Columbia.
Department of Health (DC DOH), .
·
·
the
·
the
· area residents
to
assess the public health impact of environmental contamination from hazardous
substances.
At the request
of the DC DOH, the EPA, or the Corps, between
June 1997 and the present ATSDR has prepared five health
consultations and one technical assistance document assessing
soil contamination at the site.
In December 2000, contaminated soil was identified at
the g/g) and a maximum
concentration of 498 µg/g.
During .
Hair samples were analyzed for arsenic several weeks after exposure had stopped.
Hair samples from 28 children and four adults did not indicate elevated arsenic
exposure in children or workers at this center. The property was subsequently
remediated [3, 4].
In March 2002, a second exposure investigation examined individuals
in the 23
adults and nine children aged 16
months to 13 years.
These individuals lived in 13 homes .at which elevated
composite soil arsenic levels
were found in the yards. These
individuals’ urine and
hair were tested and
in
each of their homes household dust was analyzed for arsenic.
Urine and hair arsenic testing showed low levels of arsenic exposure not
expected to cause health problems in this population [5].
On February 10 and 15, 2001, Washington Occupational
Health Associates, Inc. (WOHA), collected hair and urine samples from students and
staff at students
and
staff who attended the Center in the past 12 months,
maintenance and grounds crew members, and athletes who use
the intramural fields. Sixty-six persons (39
adults and 27 children) provided hair samples. Four
adults provided urine samples.
WOHA concluded that their exposure investigation indicated
no elevated levels of arsenic in the population tested [6].
The Corps has continued to characterize soil contamination
in residential properties in potentially affected .
This testing documented arsenic levels in composite soil samples collected from
residential areas. The samples
ranged
from background levels to a maximum of 202 parts per million (ppm). Residents
of C. DOH asked ATSDR to evaluate potential
exposure to arsenic in residents of contaminated properties..
The Spring Valley
Science Advisory Panel recommended the second phase of this exposure
investigation
The . Panel was
concerned
that the first phase of the exposure investigation was conducted in early
spring—a time of little
outdoor activity and, consequently, little
potential for soil
contact. By performing the investigation at a time of presumed maximal exposure
activities, ATSDR was
able to exclude hair analysis (which is not considered
a reliable indicator of arsenic exposure) and focus on arsenic levels
in urine.
Within a few days
following exposure, ingested arsenic
is rapidly excreted from the body into the urineAccordingly, ATSDR analyzed urine
samples for arsenic as an indicator of exposure within the preceding few days
[7]. The urine samples were analyzed for either total arsenic or speciated
arsenic (inorganic arsenic, dimethyl arsenic acid, and methylarsonic acid).
In this .
health consultation
the term “inorganic
arsenic”
is used interchangeably with “speciated
arsenic”
and refers collectively to all inorganic forms of arsenic, including dimethyl arsenic acid
and methylarsonic acid. By conducting speciated analysis, exposure to inorganic
arsenic was differentiated from exposure to less toxic forms of arsenic found
in food,
such as fish and shellfish [8].
To
assess exposure to arsenic, ATSDR tested urine in classified
into one of three groups: (1) individuals who participated in the first exposure
investigation, (2) individuals who were living on, or adjacent to, property
under
remediatation,
and (3) individuals who had a single,
elevated level of arsenic in their yard.
Prior to testing, each participant—and
a parent or legal guardian of each minor participant— was required to sign an informed consent/assent form. Sample
copies of these forms are in Attachment A. In addition to completing a consent
form, each family was asked a few questions about their exposure history.
Individual
test results and an explanation of their meaning were
provided to the participants in writing. An ATSDR physician was available
to discuss individual results by phone and,
during
a community visit at the local hospital, in person.
Recommendations for follow-up actions were made, if indicated. Individual
test results were not made available to the public;
confidentiality
was protected according to federal and state laws.
DC DOH staff distributed
urine specimen
cups and instructions to
all participants in the exposure investigation.
Participants were advised not to eat fish or shellfish for 3 days before donating
a first-morning void urine sample. In
an attempt to collect urine at the time of the highest likelihood of exposure—that
is, during peak outside activities or during soil remediation—urine
collection was spread over the late summer and fall.
The urine samples were sent to National Medical Services
laboratories in g/L)
and as micrograms of arsenic per gram of creatinine (µg/g
creatinine) [9].
A “Brief Arsenic Exposure Questionnaire” (Attachment
B) was administered at the time of urine sampling. This questionnaire revealed
eight families who owned pets
that spend time outdoors; thus the pets
might be a source of soil being tracked into the house. Six individuals reported
having recent contact
with soil in their yard and one individual
reported being a smoker. Three persons reported
eating seafood within a short time of providing the sample.
All individuals tested had total urinary arsenic levels between non-detect and 76 g/L. The detection limit was 1.0 µg/L. Most (93%, 37/40) of the participants in this exposure investigation had inorganic urinary arsenic levels of less than 10 µg/L—interpreted by the National Medical Services as “non-detect” and by ATSDR as “not elevated.” A few (7%, 3/40) of the individualshad reportable levels of inorganic arsenic in their urine 10 µg/L, 14 µg/L, and 29 µg/L. When adjusted for dilution using creatinine correction methods, these three individuals’ inorganic arsenic levels were 7 µg/g creatinine, 24.5 µg/g creatinine, and 13.4 µg/g creatinine, respectively. Attachment C contains a table of individual results grouped by household.
During this investigation
some inconsistencies appeared in the laboratory’s procedures for analyzing
urine arsenic. As stated in the exposure investigation protocol (Attachment
D), ATSDR requested total and speciated arsenic analysis for all urine specimens.
National Medical Services’ policy, however,
was only to speciate
samples with a total arsenic level above 20 µg/L. Because the discrepancy
between the policy and ATSDR’s request was discovered midway through the investigation,
some samples were only tested for total arsenic. National Medical Services
also erred in only reporting speciated results for some samples rather than
reporting both total and speciated results. However, none of these procedural
inconsistencies compromised the overall assessment of arsenic exposure in
this population. All elevated total arsenic samples were speciated and no
speciated results were high enough to indicate the potential for adverse health
effects.
To evaluate exposure, arsenic
is
measured in urine, hair, or blood. Measurement of arsenic
in blood is not a reliable indicator of chronic exposure to low levels of
arsenic—it
is cleared from the blood within a few hours and reflects only very recent
exposure. Blood arsenic levels also are difficult to interpret because the
relationship between levels of exposure and blood concentrations has not been
well established [10].
Urine arsenic is the most reliable method for measuring
arsenic exposure, particularly exposures occurring within a few days of the
specimen collection. Fluctuations
in urine excretion rates
make a
24-hour collection
an
optimal sample.
Ease of collection,
however, has
resulted in most
exposure studies uing a
first-morning void or a random samplesIn fact, the first-morning
void urine results have correlated well with 24-hour results [7]. Speciated
urinary arsenic is preferable to total urinary arsenic because the speciated
forms can distinguish between exposure to inorganic arsenic and its metabolites
and the relatively nontoxic forms of organic arsenic commonly found in seafood
[7, 8].
Individuals
in this exposure investigation had their urine tested for total arsenic (which
could come from all sources—food, water, air, soil, and dust),
for
inorganic arsenic (which might be coming from contaminated soil and dust),
or for both. The total urinary arsenic is mostly organic
arsenic from food sources, which is much less toxic than inorganic arsenic.
If the total urinary arsenic was not elevated, inorganic arsenic testing was
not always performed.
This exposure investigation (EI) included individuals who (1)
participated in the first phase of the exposure investigation, (2) who were
living on, or adjacent to, property that was being remediated, or
(3) who
had a single elevated level of arsenic in their yard. Nine of the 13 households from
the first EI chose to participate in this second EI. Three of these families
were having their yards remediated when the urine testing was done. An additional
six households fell into the second group of those who had their urine tested
while an adjacent property was under remediation.
Four more households were added to this EI because they had one elevated arsenic
level in their yard.
The American Conference of Industrial Hygienists maintains
guidance values for assessing the level of contaminants in workers who are
potentially exposed in occupational settings. For the monitoring of worker’s
urinary inorganic arsenic levels, concentrations
up to 35 mg/L are considered acceptable.
Although none of the level is relevant because it is below the point at
which adverse health effects are expected in a worker population. None of
the 40 exposure investigation participants had inorganic arsenic levels above
35 mg/L.
In summary, the urine arsenic levels in this exposure
investigation show low levels of exposure, consistent with what might be found
in the general population. These levels would not be expected to cause any
health problems. Only three of the individuals tested had reportable inorganic
arsenic levels (10 µg/L
or higher). All three of the individuals with inorganic arsenic in their urine
were adults. Two of the elevated inorganic arsenic levels were from the same
household. When adjusting the results using creatinine correction methods,
one of the individuals with a slightly elevated result (10 µg/L) had an adjusted inorganic arsenic
level (7 µg/g
creatinine) below the reportable limit.
All individuals tested had total urinary arsenic between
non-detect and 76 µg/L.
The detection level was 1.0 µg/L.
It is not clear whether the detectable levels of inorganic arsenic in the
three individuals are related to soil arsenic contamination. While dietary
arsenic is comprised mostly of organic arsenic, it does contain a small percentage
of inorganic arsenic [7]. Dietary arsenic from a seafood meal can contribute
10–15%
inorganic arsenic to the total arsenic content [8]. The individual with the
inorganic arsenic level of 14 µ-g/L
had consumed seafood in the 3 days before testing.
1.
Overall, urine arsenic testing showed no significant arsenic
exposure in the population.
2. Three individuals had slight elevations in their urine inorganic arsenic levels.
3. These levels are not expected to cause health problems.
1. Individuals with mild elevations of inorganic arsenic should have follow-up urinalysis for arsenic.
2. All of the tested individuals should discuss their results with their personal health care provider.
3. Individuals, or their health care providers, can discuss their results with an ATSDR physician if they choose to do so.
Prepared
by
Robert H. Johnson, MD
Medical Officer
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Steve Dearwent
Epidemiologist
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Loretta Bush
Health Communication Specialist
Community Involvement Branch
Division of Health Assessment and Consultation
Reviewed
by:
John E. Abraham, PhD, MPH
Chief
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Susan Metcalf, MD
Section Chief
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
1.
US
Environmental Protection Agency.
2. Agency
for Toxic Substances and Disease Registry. Public
Health Consultation for
assessment of
soil sampling results at the .
3. Agency
for Toxic Substances and Disease Registry. Report assessing public health
implications of arsenic in soils at the
4. Agency
for Toxic Substances and Disease Registry. Health
consultation/exposure investigation for
Spring Valley Chemical Munitions (a.k.a. ,.
5. Agency
for Toxic Substances and Disease Registry. Exposure investigation for Spring Valley Neighborhood (a.k.a.
Spring Valley Chemical Munitions/American University) :
6. Washington
Occupational Health Associates Inc. Arsenic exposure investigation at .
2001
Mar 26.
7. Agency
for Toxic Substances and Disease Registry. Toxicological profile for arsenic
(update).
8.
Kalman, DA et al. The effect of variable environmental arsenic contamination
on urinary concentrations of arsenic species. Enviro
Health Perspectn
1990;89:145–51.
9.
National
Medical Services. Product services manual.
10. National
Research Council. Arsenic in drinking water.
11. Norin
H et al. Concentration of inorganic and total arsenic in fish from industrially
polluted water. Chemosphere 1985;14:325-34.