[Federal Register: June 13, 2007 (Volume 72, Number 113)]
[Rules and Regulations]
[Page 32533-32540]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr13jn07-9]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 180
[EPA-HQ-OPP-2006-0559; FRL-8133-2]
Diuron; Pesticide Tolerance
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: This regulation establishes tolerances for diuron in or on
cactus (with regional restrictions for use); spearmint, tops;
peppermint, tops; and fish-freshwater finfish, farm raised.
Interregional Research Project Number 4 (IR-4) and the Catfish Farmers
of America requested these tolerances under the Federal Food, Drug, and
Cosmetic Act (FFDCA).
DATES: This regulation is effective June 13, 2007. Objections and
requests for hearings must be received on or before August 13, 2007,
and must be filed in accordance with the instructions provided in 40
CFR part 178 (see also Unit I.C. of the SUPPLEMENTARY INFORMATION).
ADDRESSES: EPA has established a docket for this action under docket
identification (ID) number EPA-HQ-OPP-2006-0559. To access the
electronic docket, go to http://www.regulations.gov, select ``Advanced
Search,'' then ``Docket Search.'' Insert the docket ID number where
indicated and select the ``Submit'' button. Follow the instructions on
the regulations.gov web site to view the docket index or access
available documents. All documents in the docket are listed in the
docket index available in regulations.gov. Although listed in the
index, some information is not publicly available, e.g., Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. Certain other material, such as copyrighted
material, is not placed on the Internet and will be publicly available
only in hard copy form. Publicly available docket materials are
available in the electronic docket at http://www.regulations.gov, or,
if only available in hard copy, at the OPP
[[Page 32534]]
Regulatory Public Docket in Rm. S-4400, One Potomac Yard (South Bldg.),
2777 S. Crystal Dr., Arlington, VA. The Docket Facility is open from
8:30 a.m. to 4 p.m., Monday through Friday, excluding legal holidays.
The Docket Facility telephone number is (703) 305-5805.
FOR FURTHER INFORMATION CONTACT: Barbara Madden, Registration Division
(7505P), Office of Pesticide Programs, Environmental Protection Agency,
1200 Pennsylvania Ave., NW., Washington, DC 20460-0001; telephone
number: (703) 305-6463; e-mail address: madden.barbara@epa.gov.
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this Action Apply to Me?
You may be potentially affected by this action if you are an
agricultural producer, food manufacturer, or pesticide manufacturer.
Potentially affected entities may include, but are not limited to those
engaged in the following activities:
Crop production (NAICS code 111), e.g., agricultural
workers; greenhouse, nursery, and floriculture workers; farmers.
Animal production (NAICS code 112), e.g., cattle ranchers
and farmers, dairy cattle farmers, livestock farmers.
Food manufacturing (NAICS code 311), e.g., agricultural
workers; farmers; greenhouse, nursery, and floriculture workers;
ranchers; pesticide applicators.
Pesticide manufacturing (NAICS code 32532), e.g.,
agricultural workers; commercial applicators; farmers; greenhouse,
nursery, and floriculture workers; residential users.
This listing is not intended to be exhaustive, but rather to
provide a guide for readers regarding entities likely to be affected by
this action. Other types of entities not listed in this unit could also
be affected. The North American Industrial Classification System
(NAICS) codes have been provided to assist you and others in
determining whether this action might apply to certain entities. If you
have any questions regarding the applicability of this action to a
particular entity, consult the person listed under FOR FURTHER
INFORMATION CONTACT.
B. How Can I Access Electronic Copies of this Document?
In addition to accessing an electronic copy of this Federal
Register document through the electronic docket at http://www.regulations.gov
, you may access this Federal Register document
electronically through the EPA Internet under the ``Federal Register''
listings at http://www.epa.gov/fedrgstr. You may also access a
frequently updated electronic version of EPA's tolerance regulations at
40 CFR part 180 through the Government Printing Office's pilot e-CFR
site at http://www.gpoaccess.gov/ecfr.
C. Can I File an Objection or Hearing Request?
Under section 408(g) of the FFDCA, any person may file an objection
to any aspect of this regulation and may also request a hearing on
those objections. You must file your objection or request a hearing on
this regulation in accordance with the instructions provided in 40 CFR
part 178. To ensure proper receipt by EPA, you must identify docket ID
number EPA-HQ-OPP-2006-0559 in the subject line on the first page of
your submission. All requests must be in writing, and must be mailed or
delivered to the Hearing Clerk as required by 40 CFR part 178 on or
before August 13, 2007.
In addition to filing an objection or hearing request with the
Hearing Clerk as described in 40 CFR part 178, please submit a copy of
the filing that does not contain any CBI for inclusion in the public
docket that is described in ADDRESSES. Information not marked
confidential pursuant to 40 CFR part 2 may be disclosed publicly by EPA
without prior notice. Submit this copy, identified by docket ID number
EPA-HQ-OPP-2006-0559, by one of the following methods:
Federal eRulemaking Portal: http://www.regulations.gov.
Follow the on-line instructions for submitting comments.
Mail: Office of Pesticide Programs (OPP) Regulatory Public
Docket (7502P), Environmental Protection Agency, 1200 Pennsylvania
Ave., NW., Washington, DC 20460-0001.
Delivery: OPP Regulatory Public Docket (7502P),
Environmental Protection Agency, Rm. S-4400, One Potomac Yard (South
Bldg.), 2777 S. Crystal Dr., Arlington, VA. Deliveries are only
accepted during the Docket's normal hours of operation (8:30 a.m. to 4
p.m., Monday through Friday, excluding legal holidays). Special
arrangements should be made for deliveries of boxed information. The
Docket Facility telephone number is (703) 305-5805.
II. Petition for Tolerance
In the Federal Register of July 26, 2006 (71 FR 42390) (FRL-8079-
4), EPA issued a notice pursuant to section 408(d)(3) of FFDCA, 21
U.S.C. 346a(d)(3), announcing the filings of a pesticide petitions (PP
2E6438, 6E3390 and 6F4680) by Interregional Research Project Number 4
(IR-4), 681 Highway 1 South, North Brunswick, NJ 08902 and the Catfish
Farmers of America, 1100 Hwy. 82 East, Suite 202, Indianola, MS 38751.
The petitions requested that 40 CFR 180.106 be amended by establishing
tolerances for residues of the herbicide diuron (3-(3,4-
dichlorophenyl)-1,1-dimethylurea in or on cactus, prickly pear at 0.05
part per million (ppm) (6E3390), mint at 1.5 ppm (2E6438) and
freshwater finfish, farm raised at 2.0 ppm (6F4680). That notice
referenced a summary of the petitions prepared by Dupont, the
registrant, which is available to the public in the docket, http://www.regulations.gov.
Comments received on the notice of filing are
discussed in Unit IV.C.
Based upon review of the data supporting the petition, EPA has
recommended certain changes to the petitions including:
1. Revised tolerance levels for certain commodities;
2. A revised tolerance expression to be applied to all new uses;
and
3. Revised commodity terms for some commodities.
The reasons for these changes are explained in Unit V.
III. Aggregate Risk Assessment and Determination of Safety
Section 408(b)(2)(A)(i) of the FFDCA allows EPA to establish a
tolerance (the legal limit for a pesticide chemical residue in or on a
food) only if EPA determines that the tolerance is ``safe.'' Section
408(b)(2)(A)(ii) of the FFDCA defines ``safe'' to mean that ``there is
a reasonable certainty that no harm will result from aggregate exposure
to the pesticide chemical residue, including all anticipated dietary
exposures and all other exposures for which there is reliable
information.'' This includes exposure through drinking water and in
residential settings, but does not include occupational exposure.
Section 408(b)(2)(C) of the FFDCA requires EPA to give special
consideration to exposure of infants and children to the pesticide
chemical residue in establishing a tolerance and to ``ensure that there
is a reasonable certainty that no harm will result to infants and
children from aggregate exposure to the pesticide chemical
residue....'' These provisions were added to the FFDCA by the Food
Quality Protection Act (FQPA) of 1996.
Consistent with section 408(b)(2)(D) of FFDCA, and the factors
specified in section 408(b)(2)(D) of FFDCA, EPA has reviewed the
available scientific data and other relevant information in support of
this action. EPA has sufficient data to assess the hazards of
[[Page 32535]]
and to make a determination on aggregate exposure for the petitioned-
for tolerance for combined residues of diuron (3-(3,4-dichlorophenyl)-
1,1-dimethylurea and its metabolites convertible to 3,4-dichloroaniline
on cactus at 0.05 ppm, spearmint, tops at 1.5 ppm, peppermint, tops at
1.5 ppm and fish - freshwater finfish, farm raised at 2.0 ppm. EPA's
assessment of exposures and risks associated with establishing the
tolerance follows.
A. Toxicological Profile
EPA has evaluated the available toxicity data and considered its
validity, completeness, and reliability as well as the relationship of
the results of the studies to human risk. EPA has also considered
available information concerning the variability of the sensitivities
of major identifiable subgroups of consumers, including infants and
children. Specific information on the studies received and the nature
of the adverse effects caused by diuron as well as the no-observed-
adverse-effect-level (NOAEL) and the lowest-observed-adverse-effect-
level (LOAEL) from the toxicity studies can be found at http://www.regulations.gov.
The referenced document is available in the docket
established by this action, which is described under ADDRESSES, and is
identified as EPA-HQ-OPP-2006-0059. Additional information regarding
this chemical can also be found in the docket for the reregistration
eligibility decision (RED) for diuron identified as EPA-HQ-OPP-2002-
0249.
Diuron has low acute toxicity (Toxicity Category 3-4) by the oral,
dermal, or inhalation exposure routes. Diuron is not an eye or skin
irritant, and not a skin sensitizer. The primary target organs are the
hematopoietic system, the bladder, and renal pelvis. Erythrocyte damage
resulted in hemolytic anemia and compensatory hematopoiesis, which were
manifested as significantly decreased erythrocyte counts, hemoglobin
levels, and hematocrit, and increased mean corpuscular volume (MCV),
mean corpuscular hemoglobin (MCH), abnormal erythrocyte forms,
reticulocyte counts, and leukocyte count. Consistent observations of
erythrocytic regeneration were seen in chronic toxicity studies in
rats, mice and dogs. Gross pathology findings in chronic rat and mouse
studies showed increased incidences of urinary bladder edema and wall
thickening at high doses. Microscopic evaluation showed dose-related
increases in the severity of epithelial focal hyperplasia of the
urinary bladder and renal pelvis in both sexes. The available data did
not reveal any developmental or reproductive toxicity. The
Carcinogenicity Peer Review Committee (CPRC) characterized diuron as a
``known/likely'' human carcinogen based on urinary bladder carcinomas
in both sexes of the Wistar rat, kidney carcinomas in the male rat, and
mammary gland carcinomas in the female NMRI mouse. Diuron was not
mutagenic in bacteria or in cultured mammalian cells and no indication
of DNA damage in primary rat hepatocytes was observed. There were
marginal statistically significant increases in cells with structural
aberrations in a Sprague Dawley rat in vivo bone marrow chromosomal
aberration assay. However, the levels of aberrations were within
historical control range and assessed negative.
The Metabolism Assessment Review Committee (MARC) recommended that
a separate dietary cancer assessment be conducted for N'-(3-
chlorophenyl)-N,N-dimethyl urea (MCPDMU), a potential residue of
concern in drinking water, but not found in food (in plant or animal
metabolism studies). The MARC raised concerns for MCPDMU based on an
analogous compound, N'-(4-chlorophenyl)-N,N-dimethyl urea (monuron).
With the exception of the position of the chlorine, the structures are
identical. There are cancer concerns for monuron but the target organs
are different than those affected by diuron. In the absence of the data
needed for a more comprehensive evaluation of MCPDMU, the carcinogenic
risk assessment was conducted using the Q1* of monuron.
B. Toxicological Endpoints
For hazards that have a threshold below which there is no
appreciable risk, the toxicological level of concern (LOC) is derived
from the highest dose at which no adverse effects are observed (the
NOAEL) in the toxicology study identified as appropriate for use in
risk assessment. However, if a NOAEL cannot be determined, the lowest
dose at which adverse effects of concern are identified (the LOAEL) is
sometimes used for risk assessment. Uncertainty/safety factors (UF) are
used in conjunction with the LOC to take into account uncertainties
inherent in the extrapolation from laboratory animal data to humans and
in the variations in sensitivity among members of the human population
as well as other unknowns. Safety is assessed for acute and chronic
risks by comparing aggregate exposure to the pesticide to the acute
population adjusted dose (``aPAD'') and chronic population adjusted
dose (``cPAD''). The aPAD and cPAD are calculated by dividing the LOC
by all applicable uncertainty/safety factors. Short-, intermediate, and
long-term risks are evaluated by comparing aggregate exposure to the
LOC to ensure that the margin of exposure (``MOE'') called for by the
product of all applicable uncertainty/safety factors is not exceeded.
For non-threshold risks, the Agency assumes that any amount of
exposure will lead to some degree of risk and estimates risk in terms
of the probability of occurrence of additional adverse cases.
Generally, cancer risks are considered non-threshold. For more
information on the general principles EPA uses in risk characterization
and a complete description of the risk assessment process, see http://www.epa.gov/fedrgstr/EPA-PEST/1997/November/Day-26/p30948.htm
.
A summary of the toxicological endpoints for diruon used for human
risk assessment can be found at http://www.regulations.gov in document Diuron.
Updated Aggregate Risk Assessment to Support Permanent Tolerances for
Residues in Prickly Pear Cactus, Peppermint Tops, Spearmint Tops, and
Freshwater Finfish, Farm-Raised at page 4 in Docket ID EPA-HQ-OPP-2006-
0059.
There are no adverse effects attributed to a single exposure
identified in any available studies for diuron. In addition, diuron has
low acute toxicity and no developmental or neurotoxic concerns.
Therefore, no acute dietary endpoint was chosen and no acute dietary
risk assessment was conducted. Also, no systemic toxicity was observed
following repeated dermal dosing up to 1,200 mg/kg/day. Therefore, no
short- or intermediate-term dermal endpoints were chosen either. The
short-term incidental oral and the inhalation endpoints are based on
decreased maternal body weight and food consumption observed in a
rabbit developmental toxicity study [No Observable Adverse Effect Level
(NOAEL) = 10 mg/kg/day]. The intermediate-term incidental oral and
intermediate-term inhalation endpoints are based on hematological
effects observed at 10 mg/kg at 6 months in the chronic rat study. The
NOAEL is 1 mg/kg/day. The chronic dietary, and long-term dermal and
inhalation endpoints are based on hemolytic anemia and compensatory
hematopoiesis [Lowest Observable Adverse Effect Level (LOAEL) = 1.0 mg/
kg/day]. Since the dose and endpoint for establishing the chronic
dietary reference Dose (RfD) is a LOAEL and a NOAEL was not
established, a total uncertainty factor (UF) of 1,000 was applied (a UF
of 100 to account for both interspecies extrapolation and intra-species
[[Page 32536]]
variability and an UF of 10 since the 10X FQPA safety factor has been
retained to protect infants and children). A low dose linear
extrapolation model with a Q1* of 1.91 x 10-\2\
(mg/kg/day)-\1\was applied to the animal data for the
quantification of human risk to diuron, based on the urinary bladder
carcinomas in the rat.
As discussed in Unit III.A., a separate dietary cancer assessment
was conducted for N'-(3-chlorophenyl)-N,N-dimethyl urea (MCPDMU), a
potential residue of concern in drinking water, but not found in food.
A low dose linear extrapolation model with a Q1* of 1.52 x
10-\2\ (mg/kg/day)-\1\ was applied to the animal
data for the quantification of human risk, based on male rat liver
neoplastic nodule and/or carcinoma combined tumor rates.
C. Exposure Assessment
1. Dietary exposure from food and feed uses. In evaluating dietary
exposure to diuron, EPA considered exposure under the petitioned-for
tolerances as well as all existing diuron tolerances in (40 CFR
180.106). EPA assessed dietary exposures from diuron and its
metabolites convertible to 3,4-dichloroaniline in food as follows:
i. Acute exposure. Quantitative acute dietary exposure and risk
assessments are performed for a food-use pesticide, if a toxicological
study has indicated the possibility of an effect of concern occurring
as a result of a one-day or single exposure.
No such effects were identified in the toxicological studies for
diuron; therefore, a quantitative acute dietary exposure assessment is
unnecessary.
ii. Chronic exposure. In conducting the chronic dietary exposure
assessment EPA used the food consumption data from the USDA 1994-1996
and 1998 Nationwide Continuing Surveys of Food Intake by Individuals
(CSFII). As to residue levels in food, the EPA analyses incorporated
tolerance level residues for some commodities as well as anticipated
residues (ARs) for other commodities, based on a combination of average
field trial data and USDA/Pesticide Data Program (PDP) monitoring data.
The chronic exposure estimates were further refined with percent crop
treated (PCT) information for some crops. In some cases, DEEM\(TM)\
(ver. 7.78) default processing factors were used, but empirical
processing factors were used when available.
iii. Cancer. --a. Diuron. In conducting the cancer dietary exposure
assessment EPA used the food consumption data from the USDA 1994-1996
and 1998 Nationwide Continuing Surveys of Food Intake by Individuals
(CSFII). As to residue levels in food, the EPA analyses incorporated
tolerance level residues for some commodities as well as anticipated
residues (ARs) for other commodities, based on a combination of average
field trial data and USDA PDP monitoring data. The cancer exposure
estimates were further refined with PCT information for some crops. In
some cases, DEEM\(TM)\ (ver. 7.78) default processing factors were
used, but empirical processing factors were used when available.
b. MCPDMU. EPA has identified MCPDMU as a potential residue of
concern of diuron that may be found in drinking water but not found in
food. In the absence of a metabolism study in fish, based on potential
concern for residues of the drinking water, EPA conducted an assessment
based on a worst-case dietary exposure analysis for the degradate
MCPDMU, including residues in drinking water and a conservative
estimate of potential residues in fish. EPA estimated the MCPDMU
drinking water residue value of 1 ppb, based on monitoring data and
assumed 25% (i.e., 0.5 ppm) of the residue in fish could be attributed
to the degradate. This is a conservative assumption of a 500-fold
accumulation of the degradate in fish, whereas acceptable metabolism
studies in rat, ruminants and poultry indicate the majority of the
residue in animals consists of dichlorinated and hydroxy metabolites;
further, the rat metabolism study indicates diuron residues do not
bioaccumulate. Therefore, the assumption that 25% of the tolerance-
level residue in fish is comprised of the MCPDMU degradate is
considered to be conservative.
iv. Anticipated residue and PCT information. Section 408(b)(2)(E)
of the FFDCA authorizes EPA to use available data and information on
the anticipated residue levels of pesticide residues in food and the
actual levels of pesticide residues that have been measured in food. If
EPA relies on such information, EPA must pursuant to section 408(f)(1)
of FFDCA require that data be provided 5 years after the tolerance is
established, modified, or left in effect, demonstrating that the levels
in food are not above the levels anticipated. For the present action,
EPA will issue such data call-ins as are required by section
408(b)(2)(E) of FFDCA and authorized under section 408(f)(1) of FFDCA.
Data will be required to be submitted no later than 5 years from the
date of issuance of this tolerance.
Section 408(b)(2)(F) of the FFDCA states that the Agency may use
data on the actual percent of food treated for assessing chronic
dietary risk only if:
a. The data used are reliable and provide a valid basis to show
what percentage of the food derived from such crop is likely to contain
such pesticide residue;
b. The exposure estimate does not underestimate exposure for any
significant subpopulation group; and
c. Data are available on pesticide use and food consumption in a
particular area, the exposure estimate does not understate exposure for
the population in such area. In addition, the Agency must provide for
periodic evaluation of any estimates used. To provide for the periodic
evaluation of the estimate of PCT as required by section 408(b)(2)(F)
of FFDCA, EPA may require registrants to submit data on PCT.
The Agency used PCT information as follows:
1% alfalfa, 1% almonds, 10% apples, 5% artichokes, 55% asparagus,
1% barley, 50% blackberries, 30% blueberries, 1% corn, 25% cotton, 20%
filberts, 10% grapes, 45% grapefruit, 15% lemon, 50% limes, 20%
Macadamia nut, 5% oats, 15% olives, 50% oranges, 10% peaches, 10%
pears, 5% pecans, 90% mint, 1% pistachios, 30% raspberries, 15%
sugarcane, 30% tangerines, 15% walnuts, and 1%wheat.
EPA uses an average PCT for chronic dietary risk analysis. The
average PCT figure for each existing use is derived by combining
available federal, state, and private market survey data for that use,
averaging by year, averaging across all years, and rounding up to the
nearest multiple of five percent except for those situations in which
the average PCT is less than one. In those cases < 1% is used as the
average and < 2.5% is used as the maximum. EPA uses a maximum PCT for
acute dietary risk analysis. The maximum PCT figure is the single
maximum value reported overall from available federal, state, and
private market survey data on the existing use, across all years, and
rounded up to the nearest multiple of five percent. In most cases, EPA
uses available data from United States Department of Agriculture/
National Agricultural Statistics Service (USDA/NASS), Proprietary
Market Surveys, and the National Center for Food and Agriculture Policy
(NCFAP) for the most recent six years.
There are existing tolerances for residues of diuron on peppermint,
hay at 2 ppm. However, the EPA has determined the preferred commodity
term should be peppermint, tops. Therefore, the PCT estimates used for
mint are based on the existing registration and are not projections.
[[Page 32537]]
The Agency believes that the three conditions listed in Unit
III.C.iv. have been met. With respect to Condition 1, PCT estimates are
derived from Federal and private market survey data, which are reliable
and have a valid basis. The Agency is reasonably certain that the
percentage of the food treated is not likely to be an underestimation.
As to Conditions 2 and 3, regional consumption information and
consumption information for significant subpopulations is taken into
account through EPA's computer-based model for evaluating the exposure
of significant subpopulations including several regional groups. Use of
this consumption information in EPA's risk assessment process ensures
that EPA's exposure estimate does not understate exposure for any
significant subpopulation group and allows the Agency to be reasonably
certain that no regional population is exposed to residue levels higher
than those estimated by the Agency. Other than the data available
through national food consumption surveys, EPA does not have available
information on the regional consumption of food to which diuron may be
applied in a particular area.
2. Dietary exposure from drinking water. The drinking water
exposure assessment conducted in conjunction with the 2003 RED noted
that surface water monitoring data resulted in diuron residues less
than 1 parts per billion (ppb) (http://www.regulations.gov, document
0006 - Docket ID EPA-HQ-OPP-2002-0249). For ground water, modeling
results indicted that residues of diuron and degradates would be at
most 0.6 ppb for long-term exposure assessment. For the current
assessment, EPA used PDP monitoring data from 2003 and 2004, in which
1,072 samples of raw and treated water were analyzed for diuron
residues. Residues were detected in 12 samples, ranging from 27 to 267
parts per trillion (ppt), with an average of 20.2 ppt (0.020 ppb). For
chronic dietary risk assessment, the water concentration of value 0.020
ppb was used to access the contribution to drinking water. These
estimates of drinking water concentrations were directly entered into
the dietary exposure model.
The drinking water exposure assessment conducted in conjunction
with the 2003 RED noted that surface water monitoring data resulted in
diuron residues less than 1 ppb. For ground water, modeling results
indicated that residues of diuron and degradates would be at most 0.6
ppb for long-term exposure assessment. The analysis in the RED noted
that the potential for residues in drinking water sources is more
likely to occur from run-off to surface water, and the ground water
sources of drinking water are likely to be less vulnerable to
contamination with diuron. The RED cited numerous monitoring studies
from areas known for high diuron usage. The drinking water risks in the
RED were calculated from diuron residues in a Florida surface water
monitoring study in which the highest residue found was 1.2 ppb, but
the 90\th\ and 95\th\ percentile residues were both less than the limit
of detection in the study, which ranged from 0.2 to 0.4 ppb. For the
current assessment, drinking water residues were estimated from PDP
monitoring data from 2003 and 2004, in which 1,072 samples of raw and
treated water were analyzed for diuron residues. Residues were detected
in 12 samples, ranging from 27 to 267 ppt, with an average detected
residue of 20.2 ppt (0.02 ppb). This average of detected residues was
considered to be more appropriate for estimating cancer risk from
drinking water than a high-end estimate of surface water residues from
the Florida monitoring data. However, the 2 sets of monitoring data
support the conclusion that potential residues in surface water are
much less than 1 ppb.
3. From non-dietary exposure. The term ``residential exposure'' is
used in this document to refer to non-occupational, non-dietary
exposure (e.g., for lawn and garden pest control, indoor pest control,
termiticides, and flea and tick control on pets).
In conjunction with the RED, the agency concluded that all
registered uses were eligible for reregistration, provided labeling
requirements and mitigation measures were observed. This included
voluntary cancellation of uses allowing application to home lawns.
Currently, all registered labels for diuron no longer allow
applications to home lawns. As a result the current uses registered
that could result in non-occupational, non-dietary exposures are diruon
added to paints and stains and residential ponds and aquariums.
Exposures of concern to diuron resulting from residential uses is
expected to be negligible. The existing residential uses for diuron
result in only short-term exposures, generally less than 7 days. No
short-term dermal endpoints have been identified for diuron. A short-
term incidental oral endpoint was identified. However, all residential
uses to home lawns have been cancelled so incidental oral exposures are
not expected. Inhalation endpoints have been identified for diuron.
However, diuron has a low vapor pressure (2 x 10-\7\ mm
Hg@30[deg]C) and therefore, absorption by the inhalation route is
likely to be low. Potential residential handler exposures from applying
paints and stains containing diuron were assessed in the 2003 RED.
Conservative assumptions included 2 days of painting per year for 50
years of a 70 year lifetime. However, based on information gathered
through the RED process it was determined that less than 1% of paint
sold contains diuron, and that such paints would likely only be used in
rooms subject to high moisture (e.g., bathrooms). Therefore, lifetime
exposure to home applicators of diuron-containing products is likely to
negligible. Postapplication inhalation exposure resulting from the use
of diuron in residential ponds and aquariums is also expected to be
minimal based on the extremely high dilution rate. Therefore, an
exposure assessment was not conducted for non-occupational, non-dietary
exposures.
4. Cumulative effects from substances with a common mechanism of
toxicity. Section 408(b)(2)(D)(v) of the FFDCA requires that, when
considering whether to establish, modify, or revoke a tolerance, the
Agency consider ``available information'' concerning the cumulative
effects of a particular pesticide's residues and ``other substances
that have a common mechanism of toxicity.''
Based on available data, EPA has previously concluded that diuron,
propanil and linuron, all of which contain 3,4 dichloroaniline (3,4-
DCA) in their structures, do not share a common mechanism of toxicity.
(Additional information regarding this conclusion can be found in the
docket for the RED for diuron identified as EPA-HQ-OPP-2002-0249.)
Propanil readily metabolizes to 3,4-DCA, but neither diuron nor
linuron metabolize to 3,4-DCA in plant or animal metabolism studies.
EPA previously recommended against aggregating residues of 3,4 DCA for
the propanil and diuron risk assessments. The following considerations
support the recommendation:
3,4-DCA is a significant residue of concern for propanil,
but is not a residue of concern per se for diuron;
The analytical method for quantifying residues of concern
from applications of diuron converts all residues to 3,4-DCA as a
technical convenience. However, 3,4-DCA is not a significant residue in
diuron plant and animal metabolism or hydrolysis studies. Therefore,
the agency determined that all residues hydrolyzable to 3,4-DCA would
be included in the tolerance expression for
[[Page 32538]]
diuron, because no validated enforcement method is available for
quantification for the actual residues of concern for diuron.
Propanil and its metabolite 3,4-DCA were found to induce
methemoglobinemia, the endpoint of concern for propanil. Diuron has not
been shown to cause this effect. Diuron induces hemolytic anemia and
compensatory hematopoiesis, which are mechanistically different from
methemoglobinemia.
Linuron and diuron metabolism studies show that both
chemicals metabolize to DCPU and DCPMU. However, for reasons that are
yet unknown, these chemicals do not induce the same toxic effects in
mammals. Submitted data indicate that diuron is primarily (though not
exclusively) metabolized by the hydroxylation of the urea group in
either the methyl or the amino position and conjugated. Linuron, on the
other hand, appears to be primarily ring-hydroxylated and conjugated.
The methoxy group is removed, followed by the methyl group, with ring
hydroxylation. Unlike linuron, hydroxylation of the phenyl ring is not
a major metabolite pathway of diuron and, both methyl groups are lost.
Methemoglobinemia is the dominant toxic effect of concern
for linuron. As mentioned above, diuron does not induce
methemoglobinemia. Mechanistic and reproductive studies show that
linuron, and to some extent propanil, is an androgen receptor
antagonist and that linuron induces testicular abnormalities in
rodents. Studies with diuron showed no indications of any endocrine
effects and no developmental or reproductive effects.
Although the mechanisms of action for the differing
effects induced by the two ureas, diuron and linuron, are not entirely
known, there is sufficient cause to believe that exposures from the two
compounds should not be cumulated.
The estimated dietary cancer risk for diuron did not
include residues from linuron and propanil since it was recognized that
the target organs for tumor induction for diuron are different from
those for linuron and propanil, and data were available which indicated
that the mechanism of action may be different for diuron.
For the purposes of this tolerance action, therefore, EPA has not
assumed that diuron has a common mechanism of toxicity with other
substances. For information regarding EPA's efforts to determine which
chemicals have a common mechanism of toxicity and to evaluate the
cumulative effects of such chemicals, see the policy statements
released by EPA's Office of Pesticide Programs concerning common
mechanism determinations and procedures for cumulating effects from
substances found to have a common mechanism on EPA's website at http://www.epa.gov/pesticides/cumulative/
.
D. Safety Factor for Infants and Children
1. In general. Section 408 of FFDCA provides that EPA shall apply
an additional (``10X'') tenfold margin of safety for infants and
children in the case of threshold effects to account for prenatal and
postnatal toxicity and the completeness of the data base on toxicity
and exposure unless EPA determines based on reliable data that a
different margin of safety will be safe for infants and children. This
additional margin of safety is commonly referred to as the FQPA safety
factor. In applying this provision, EPA either retains the default
value of 10X when reliable data do not support the choice of a
different factor, or, if reliable data are available, EPA uses a
different additional FQPA safety factor value based on the use of
traditional uncertainty/safety factors and/or special FQPA safety
factors, as appropriate.
2. Prenatal and postnatal sensitivity. There is an acceptable
developmental toxicity study in rabbits and an acceptable 2-generation
reproduction study in rats. A developmental toxicity study in rats was
classified as unacceptable due to deficiencies in analytical data on
the sample analysis; however, the EPA considers the developmental
toxicity study in rats adequate for the FQPA susceptibility assessment
based on the observation that the developmental toxicity NOAEL was
higher than the maternal NOAEL. The EPA has also concluded that a
developmental neurotoxicity (DNT) study is not required.
There is no indication of increased susceptibility to young exposed
to diuron in the available studies. In the developmental toxicity study
in rabbits, there were no developmental effects at the highest dose
tested. In the developmental toxicity study in rabbits and in the 2-
generation rat reproduction study, developmental/offspring effects were
observed only at maternally/parentally toxic dose levels.
There are no neurotoxic signs in any of the submitted subchronic or
chronic studies.
3. Conclusion. The chronic dietary endpoint for diuron used in risk
assessment is based on a LOAEL of 1 mg/kg/day from the chronic
toxicity/carcinogenicity study in rats. EPA has retained the 10X FQPA
safety factor for diuron because of reliance on a LOAEL in the rat
chronic toxicity study and because the data in that study or other
studies did not show that a smaller factor would be safe. EPA has
determined that reliable data show that it would be safe for infants
and children provided the FQPA safety factor of 10X is retained and no
additional safety factors are needed. That decision is based on the
following findings:
i. There are no uncertainties with the toxicology database other
than with regard to the lack of a NOAEL in the rat chronic toxicity
study. The only outstanding toxicity data requirement for diuron is a
28-day inhalation study which is required to address the concern for
inhalation exposure to workers during the application of diuron.
Occupational exposures are not considered under section 408 of FFDCA.
Postapplication inhalation exposure resulting from the indoor use of
diuron in paints is expected to be minimal because of the low vapor
pressure of diuron, and because diuron-treated paint is only likely to
be used in rooms where high humidity is expected (e.g... a bathroom),
and would rarely be used in the entire house based on the use pattern.
Additionally, based on information gathered through the RED process it
was determined that less than 1% of paint sold contains diuron. As a
result, non-occupational exposure to diuron via inhalation is not
expected to occur with infants and children. Therefore, the 28-day
inhalation study will not change the endpoints used in risk assessment
to address the potential risks to infants and children.
The developmental toxicity study in rats is classified as
unacceptable due to deficiencies in analyses of the test material and
dosing solutions. However, the EPA has not required the study be
repeated since it is considered adequate for the FQPA susceptibility
assessment based on the observation that the developmental toxicity
NOAEL was higher than the maternal NOAEL, and because maternal and
developmental toxicity were well-defined at their respective LOAELs.
Finally, the rabbit is considered to be the more sensitive species than
the rat for developmental toxicity, and the rabbit developmental study
is acceptable. The chronic toxicity study in dogs has also been
classified as unacceptable due to the purity of the test material, as
well as potential problems with stability and homogeneity issues
related to the test material. However, the EPA determined that a
repeated chronic dog study is not required; similar effects were
observed in rats and dogs, but the effects in the
[[Page 32539]]
rat occurred at lower doses and the rat NOAEL serves as the dose for
risk assessment. Therefore, the EPA concluded that a new chronic dog
study would not change the endpoint chosen for risk assessment.
The data base as a whole is adequate for pre- and post-natal
toxicity evaluation.
ii. There is no indication of quantitative or qualitative increased
susceptibility of rats or rabbits to in utero or postnatal exposure.
There is no indication of increased susceptibility to young exposed to
diuron in the available studies. In the developmental toxicity study in
rabbits, there were no developmental effects at the highest dose
tested. In the developmental toxicity study in rabbits and in the 2-
generation rat reproduction study, developmental/offspring effects were
observed only at maternally/parentally toxic dose levels.
iii. There are no neurotoxic signs in any of the submitted
subchronic or chronic studies. A developmental neurotoxicity study
(DNT) for diuron is not required.
iv. There are no residual uncertainties identified in the exposure
databases. The dietary (food and drinking water) and non-dietary
(residential) exposure assessments will not underestimate the potential
exposures for infants and children. The dietary food exposure
assessments were performed based on reliable field trial data where
tolerance level residues for some commodities as well as anticipated
residues (ARs) for other commodities, based on a combination of average
field trial data and USDA/PDP monitoring data. Average PCT values were
assumed for chronic dietary assessment for some crops and 100 PCT
treated were assumed for the remaining uses. Drinking water estimates
were based on monitoring studies and USDA/PDP monitoring data. EPA
expects any residential exposure from use of diuron to be negligible.
The EPA is confident that these assessments will not underestimate the
exposure and risks posed by diuron.
E. Aggregate Risks and Determination of Safety
Safety is assessed for acute and chronic risks by comparing
aggregate exposure to the pesticide to the acute population adjusted
dose (``aPAD'') and chronic population adjusted dose (``cPAD''). The
aPAD and cPAD are calculated by dividing the LOC by all applicable
uncertainty/safety factors. For linear cancer risks, EPA calculates the
probability of additional cancer cases given aggregate exposure. Short-
, intermediate, and long-term risks are evaluated by comparing
aggregate exposure to the LOC to ensure that the margin of exposure
(``MOE'') called for by the product of all applicable uncertainty/
safety factors is not exceeded.
1. Acute risk. As there were no toxic effects attributable to a
single dose, an endpoint of concern was not identified to quantitate
acute-dietary risk to the general population or to the subpopulation
females 13-50 years old. No acute risk is expected from exposure to
diuron.
2. Chronic risk. Using the exposure assumptions described in this
unit for chronic exposure, EPA has concluded that exposure to diruon
from food and water will utilize 19% of the cPAD for the population
group children 1-2 years old, the subpopulation group with greatest
exposure. There are no residential uses for diuron that result in
chronic residential exposure to diuron.
3. Short-term risk and Intermediate risk. Short-term and
intermediate-term aggregate exposure takes into account residential
exposure plus chronic exposure to food and water (considered to be a
background exposure level). The current uses registered that could
result in non-occupational, non-dietary exposures are from diuron added
to paints and stains as well as applications to residential ponds and
aquariums. However, EPA expects any residential exposure from use of
diuron to be negligible. Therefore, no short-term and intermediate-term
risk is expected from exposure to diuron as a result of non-occupation,
non-dietary exposures.
4. Aggregate cancer risk for U.S. population. Using the exposure
assumptions described in this unit for cancer for diuron, EPA has
concluded that exposure to diruon from food and water will result in a
cancer risk estimate of 1.4 x 10-\6\ for the general U.S.
population. This risk estimate is within the range of 1 in 1 million
that EPA considers negligible risk for cancer. EPA has generally
concluded that computed cancer risks as high as 3 in 1 million fall
within this risk range.
Using the exposure assumptions described in this unit for cancer
for the degradate MCPDMU, EPA has concluded that exposure to MCPDMU
from fish and water will result in a cancer risk estimate of 5.9 x 10\-
7\, which is not of concern.
5. Determination of safety. Based on these risk assessments, EPA
concludes that there is a reasonable certainty that no harm will result
to the general population, or to infants and children from aggregate
exposure to diuron residues.
IV. Other Considerations
A. Analytical Enforcement Methodology
Adequate enforcement methodology (gas chromatography) is available
to enforce the tolerance expression. The principle of the determination
is the hydrolysis of diuron and its metabolites by alkaline reflux to
3,4-dichloroanaline (3,4-DCA), followed by a distillation of the
aniline into an acid solution. The acid distillate is made alkaline
with concentrated base and subsequently extracted into an organic
solvent (hexane) and analyzed by gas chromatography. With the modified
method, recoveries exceeded 70% and the limit of quantitation (LOQ) is
0.01. The method may be requested from: Chief, Analytical Chemistry
Branch, Environmental Science Center, 701 Mapes Rd., Ft. Meade, MD
20755-5350; telephone number: (410) 305-2905; e-mail address:
residuemethods@epa.gov.
B. International Residue Limits
There are no Codex, Canadian, or Mexican tolerances or maximum
residue limits for diuron in cactus; spearmint, tops; peppermint, tops;
and fish - freshwater finfish, farm raised. Therefore, harmonization
with international tolerances is not an issue for this action.
C. Response to Comments
Several comments were received from a private citizen objecting to
establishment of tolerances. The Agency has received similar comments
from this commenter on numerous previous occasions. Refer to Federal
Register of June 30, 2005 (70 FR 37686; FRL-7718-3); January 7, 2005
(70 FR 1354; FRL-7691-4); and October 29, 2004 (69 FR 63096; FRL-7681-
9) for the Agency's response to these objections. In addition, the
commenter noted several adverse effects seen in animal toxicology
studies with diruon and claims because of these effects no tolerance
should be approved. EPA has found, however, that there is a reasonable
certainty of no harm to humans after considering these toxicological
studies and the exposure levels of humans to diruon.
The EPA also received an additional comment in support of this
action.
V. Conclusion
Upon completing review of the current diuron database, the Agency
concluded that the tolerance expression proposed in the Notice of
Filing should be changed to include metabolites hydrolyzable to 3,4-
dichloroaniline (3,4-DCA). This determination is based on
[[Page 32540]]
the results of the reviewed plant and animal metabolism studies.
Currently, there are existing tolerances for residues of diuron on
peppermint, hay at 2 ppm. The petitioner proposed tolerances be
established on mint at 1.5 ppm. The EPA has determined that the
preferred commodity terms are spearmint, tops and peppermint, tops and
based on the residue field trial data the appropriate tolerance level
for spearmint and peppermint should be 1.5 ppm. The EPA has also
determined the preferred commodity terms should be cactus and fish -
freshwater finfish, farm raised.
Therefore, these tolerances are established for combined residues
of diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea and its metabolites
convertible to 3,4-dichloroaniline on cactus at 0.05 ppm, spearmint,
tops at 1.5 ppm, peppermint, tops at 1.5 ppm and fish - freshwater
finfish, farm raised at 2.0 ppm.
VI. Statutory and Executive Order Reviews
This final rule establishes a tolerance under section 408(d) of
FFDCA in response to a petition submitted to the Agency. The Office of
Management and Budget (OMB) has exempted these types of actions from
review under Executive Order 12866, entitled Regulatory Planning and
Review (58 FR 51735, October 4, 1993). Because this rule has been
exempted from review under Executive Order 12866, this rule is not
subject to Executive Order 13211, Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use (66 FR 28355,
May 22, 2001) or Executive Order 13045, entitled Protection of Children
from Environmental Health Risks and Safety Risks (62 FR 19885, April
23, 1997). This final rule does not contain any information collections
subject to OMB approval under the Paperwork Reduction Act (PRA), 44
U.S.C. 3501 et seq., nor does it require any special considerations
under Executive Order 12898, entitled Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations (59 FR 7629, February 16, 1994).
Since tolerances and exemptions that are established on the basis
of a petition under section 408(d) of FFDCA, such as the tolerance in
this final rule, do not require the issuance of a proposed rule, the
requirements of the Regulatory Flexibility Act (RFA) (5 U.S.C. 601 et
seq.) do not apply.
This final rule directly regulates growers, food processors, food
handlers and food retailers, not States or tribes, nor does this action
alter the relationships or distribution of power and responsibilities
established by Congress in the preemption provisions of section
408(n)(4) of FFDCA. As such, the Agency has determined that this action
will not have a substantial direct effect on States or tribal
governments, on the relationship between the national government and
the States or tribal governments, or on the distribution of power and
responsibilities among the various levels of government or between the
Federal Government and Indian tribes. Thus, the Agency has determined
that Executive Order 13132, entitled Federalism (64 FR 43255, August
10, 1999) and Executive Order 13175, entitled Consultation and
Coordination with Indian Tribal Governments (65 FR 67249, November 6,
2000) do not apply to this rule. In addition, This rule does not impose
any enforceable duty or contain any unfunded mandate as described under
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA) (Public Law
104-4).
This action does not involve any technical standards that would
require Agency consideration of voluntary consensus standards pursuant
to section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272
note).
VII. Congressional Review Act
The Congressional Review Act, 5 U.S.C. 801 et seq., generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report to each House of the Congress and to
the Comptroller General of the United States. EPA will submit a report
containing this rule and other required information to the U.S. Senate,
the U.S. House of Representatives, and the Comptroller General of the
United States prior to publication of this final rule in the Federal
Register. This final rule is not a ``major rule'' as defined by 5
U.S.C. 804(2).
List of Subjects in 40 CFR Part 180
Environmental protection, Administrative practice and procedure,
Agricultural commodities, Pesticides and pests, Reporting and
recordkeeping requirements.
Dated: May 31, 2007.
Donald R. Stubbs,
Acting Director, Registration Division, Office of Pesticide Programs.
0
Therefore, 40 CFR chapter I is amended as follows:
PART 180--[AMENDED]
0
1. The authority citation for part 180 continues to read as follows:
Authority: 21 U.S.C. 321(q), 346a and 371.
0
2. Section 180.106 is amended by redesignating the text in paragraph
(a) as (a)(1); by adding paragraph (a)(2); and by adding text to
paragraph (c) to read as follows:
Sec. 180.106 Diuron; tolerances for residues.
(a) (1) * * *
(2) Tolerances are established for the combined residues of the
herbicide diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea and its
metabolites convertible to 3,4-dichloroaniline, in or on the following
raw agricultural commodities:
------------------------------------------------------------------------
Commodity Parts per million
------------------------------------------------------------------------
Fish - freshwater finfish, farm raised 2.0
Peppermint, tops 1.5
Spearmint, tops 1.5
------------------------------------------------------------------------
* * * * *
(c) Tolerances with regional registrations. Tolerances with a
regional registration as defined in Sec. 180.1(n) are established for
the combined residues of the herbicide diuron (3-(3,4-dichlorophenyl)-
1,1-dimethylurea and its metabolites convertible to 3,4-
dichloroaniline) in or on the raw agricultural commodities:
------------------------------------------------------------------------
Commodity Parts per million
------------------------------------------------------------------------
Cactus 0.05
------------------------------------------------------------------------
* * * * *
[FR Doc. E7-11205 Filed 6-12-07; 8:45 am]
BILLING CODE 6560-50-S