[Federal Register: October 29, 2008 (Volume 73, Number 210)]
[Rules and Regulations]
[Page 64229-64246]
[DOCID:fr29oc08-16]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[EPA-HQ-OPP-2008-0347; FRL-8388-1]

Carbaryl; Order Denying NRDC's Petition to Revoke Tolerances

AGENCY: Environmental Protection Agency (EPA).

ACTION: Order.

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SUMMARY: In this Order, EPA denies a petition requesting that EPA
revoke all pesticide tolerances for carbaryl under section 408(d) of
the Federal Food, Drug, and Cosmetic Act (FFDCA). The petition was
filed on January 10, 2005, by the Natural Resources Defense Council
(NRDC).

DATES: This Order is effective October 29, 2008. Objections and
requests for hearings must be received on or before December 29, 2008,
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-2008-0347. 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 website 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 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<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: Christina Scheltema, Special Review
and Reregistration Division (7508P), Office of Pesticide Programs,
Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460-0001; telephone number:<PHONE_NUMBER>; e-mail
address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this Action Apply to Me?

    In this document, EPA denies a petition by the NRDC to revoke
pesticide tolerances. This action may be of interest to agricultural
producers, food manufacturers, or pesticide manufacturers. 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 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-2008-0347 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 December 29, 2008.
    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-2008-0347, 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<PHONE_NUMBER>.

II. Introduction

A. What Action Is the Agency Taking?

    The NRDC filed a petition dated January 10, 2005 with EPA which,
among other things, requested that EPA revoke all tolerances for the
pesticide carbaryl established under section 408 of the FFDCA, 21
U.S.C. 346a (Ref. 1) This Order denies that aspect of the petition that
sought the revocation of the carbaryl tolerances. This Order also
denies NRDC's petition to cancel carbaryl pet collar registrations
submitted as part of NRDC's comments on the N-methyl carbamate (NMC)

cumulative assessment and dated November 26, 2007, because NRDC is
arguing that exposure to carbaryl pet collars makes the cumulative
risks presented by carbaryl unsafe (Ref. 2).

B. What Is the Agency's Authority for Taking This Action?

    Under section 408(d)(4) of the FFDCA, EPA is authorized to respond
to a section 408(d) petition to revoke tolerances either by issuing a
final rule revoking the tolerances, issuing a proposed rule, or issuing
an order denying the petition. (21 U.S.C. 346a(d)(4)).

III. Statutory and Regulatory Background

A. FFDCA/FIFRA and Applicable Regulations

    1. In general. EPA establishes maximum residue limits, or
``tolerances,'' for pesticide residues in food and feed commodities
under section 408 of the FFDCA. (21 U.S.C. 346a). Without such a
tolerance or an exemption from the requirement of a tolerance, a food
containing a pesticide residue is ``adulterated'' under section 402 of
the FFDCA and may not be legally moved in interstate commerce. (21
U.S.C. 331, 342). Monitoring and enforcement of pesticide tolerances
are carried out by the U.S. Food and Drug Administration (FDA) and the
U.S. Department of Agriculture (USDA). Section 408 was substantially
rewritten by the Food Quality Protection Act of 1996 (FQPA), which
added the provisions discussed below establishing a detailed safety
standard for pesticides, additional protections for infants and
children, and the estrogenic substances screening program. (Public Law
104-170, 110 Stat. 1489 (1996)).
    EPA also regulates pesticides under the Federal Insecticide,
Fungicide, and Rodenticide Act (FIFRA), (7 U.S.C. 136 et seq). While
the FFDCA authorizes the establishment of legal limits for pesticide
residues in food, FIFRA requires the approval of pesticides prior to
their sale and distribution, (7 U.S.C. 136a(a)), and establishes a
registration regime for regulating the use of pesticides. FIFRA
regulates pesticide use in conjunction with its registration scheme by
requiring EPA review and approval of pesticide labels and specifying
that use of a pesticide inconsistent with its label is a violation of
federal law. (7 U.S.C. 136j(a)(2)(G)). In the FQPA, Congress integrated
action under the two statutes by requiring that the safety standard
under the FFDCA be used as a criterion in FIFRA registration actions as
to pesticide uses which result in dietary risk from residues in or on
food, (7 U.S.C. 136(bb)), and directing that EPA coordinate, to the
extent practicable, revocations of tolerances with pesticide
cancellations under FIFRA. (21 U.S.C. 346a(l)(1)).
    2. Safety standard for pesticide tolerances. A pesticide tolerance
may only be promulgated or left in effect by EPA if the tolerance is
``safe.'' (21 U.S.C. 346a(b)(2)(A)(i)). This standard applies both to
petitions to establish and petitions to revoke tolerances. ``Safe'' is
defined by the statute 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.'' (21 U.S.C.
346a(b)(2)(A)(ii)). Section 408(b)(2)(D) directs EPA, in making a
safety determination, to:
    consider, among other relevant factors--...
    (v) available information concerning the cumulative effects of
such residues and other substances that have a common mechanism of
toxicity; and
    (vi) available information concerning the aggregate exposure
levels of consumers (and major identifiable subgroups of consumers)
to the pesticide chemical residue and to other related substances,
including dietary exposure under the tolerance and all other
tolerances in effect for the pesticide chemical residue, and
exposure from other non-occupational sources;

(21 U.S.C. 346a(b)(2)(D)(v), (vi) and (viii)).

    EPA must also consider, in evaluating the safety of tolerances,
``safety factors which . . . are generally recognized as appropriate
for the use of animal experimentation data.'' (21 U.S.C.
346a(b)(2)(D)(ix).
    Risks to infants and children are given special consideration.
Specifically, section 408(b)(2)(C) states that EPA:
    shall assess the risk of the pesticide chemical based on--
    (II) available information concerning the special susceptibility
of infants and children to the pesticide chemical residues,
including neurological differences between infants and children and
adults, and effects of in utero exposure to pesticide chemicals; and
    (III) available information concerning the cumulative effects on
infants and children of such residues and other substances that have
a common mechanism of toxicity. ...

 (21 U.S.C. 346a(b)(2)(C)(i)(II) and (III)).

    This provision also creates a presumptive additional safety factor
for the protection of infants and children. Specifically, it directs
that ``[i]n the case of threshold effects, ... an additional tenfold
margin of safety for the pesticide chemical residue and other sources
of exposure shall be applied for infants and children to take into
account potential pre- and post-natal toxicity and completeness of the
data with respect to exposure and toxicity to infants and children.''
(21 U.S.C. 346a(b)(2)(C)). EPA is permitted to ``use a different margin
of safety for the pesticide chemical residue only if, on the basis of
reliable data, such margin will be safe for infants and children.''
(Id.). The additional safety margin for infants and children is
referred to throughout this Order as the ``FQPA Safety Factor.''
    3. Procedures for establishing, amending, or revoking tolerances.
Tolerances are established, amended, or revoked by rulemaking under the
unique procedural framework set forth in the FFDCA. Generally, a
tolerance rulemaking is initiated by the party seeking to establish,
amend, or revoke a tolerance by means of filing a petition with EPA.
(See 21 U.S.C. 346a(d)(1)). EPA publishes in the Federal Register a
notice of the petition filing and requests public comment. (21 U.S.C.
346a(d)(3)). After reviewing the petition, and any comments received on
it, EPA may issue a final rule establishing, amending, or revoking the
tolerance, issue a proposed rule to do the same, or deny the petition.
(21 U.S.C. 346a(d)(4)).
    Once EPA takes final action on the petition by establishing,
amending, or revoking the tolerance or denying the petition, any party
may file objections with EPA and seek an evidentiary hearing on those
objections. (21 U.S.C. 346a(g)(2)). Objections and hearing requests
must be filed within 60 days. (Id.). The statute provides that EPA
shall ``hold a public evidentiary hearing if and to the extent the
Administrator determines that such a public hearing is necessary to
receive factual evidence relevant to material issues of fact raised by
the objections.'' (21 U.S.C. 346a(g)(2)(B). EPA regulations make clear
that hearings will only be granted where it is shown that there is ``a
genuine and substantial issue of fact,'' the requestor has identified
evidence ``which, if established, resolve one or more of such issues in
favor of the requestor,'' and the issue is ``determinative'' with
regard to the relief requested. (40 CFR 178.32(b)). EPA's final order
on the objections is subject to judicial review. (21 U.S.C.
346a(h)(1)).
    4. Tolerance reassessment and FIFRA reregistration. The FQPA
required that EPA reassess the safety of all pesticide tolerances
existing at the time of its enactment. (21 U.S.C. 346a(q)). EPA was
given 10 years to reassess the

approximately 10,000 tolerances in existence in 1996. In this
reassessment, EPA was required to review existing pesticide tolerances
under the new ``reasonable certainty that no harm will result''
standard set forth in section 408(b)(2)(A)(i). (21 U.S.C.
346a(b)(2)(A)(i)). This reassessment was substantially completed by the
August 3, 2006 deadline. Tolerance reassessment was generally handled
in conjunction with a similar program involving reregistration of
pesticides under FIFRA. (7 U.S.C. 136a-1). Reassessment and
reregistration decisions were generally combined in a document labeled
a Reregistration Eligibility Decision (``RED'').

B. EPA's Approach to Dietary Risk Assessment

    EPA performs a number of analyses to determine the risks from
aggregate exposure to pesticide residues. A short summary is provided
below to aid the reader. For further discussion of the regulatory
requirements of section 408 of the FFDCA and a complete description of
the risk assessment process, see http://www.epa.gov/fedrgstr/EPA-PEST/
1999/January/Day-04/p34736.htm.(64 FR 162)
    To assess the risk of a pesticide tolerance, EPA combines
information on pesticide toxicity with information regarding the route,
magnitude, and duration of exposure to the pesticide. The risk
assessment process involves three distinct steps: (1) identification of
the toxicological hazards posed by a pesticide and determination of the
exposure ``level of concern'' for humans; (2) estimation of human
exposure; and (3) characterization of human risk based on comparison of
human exposure to the level of concern.
    1. Hazard identification and determination of the level of concern.
Any risk assessment begins with an evaluation of a chemical's inherent
properties, and whether those properties have the potential to cause
adverse effects (i.e., hazard identification). EPA then evaluates the
hazards to determine the most sensitive and appropriate adverse effect
of concern, based on factors such as the effect's relevance to humans
and the likely routes of exposure. Once a pesticide's potential hazards
are identified, EPA determines a toxicological level of concern for
evaluating the risk posed by human exposure to the pesticide. In this
step of the risk assessment process, EPA essentially evaluates the
levels of exposure to the pesticide at which effects might occur. An
important aspect of this determination is assessing the relationship
between exposure (dose) and response (often referred to as the dose-
response analysis). Another aspect is the determination of whether the
effect is associated with a threshold dose (i.e., the effect is seen
only at or above a certain dose) or whether the effect can occur at any
dose (such as some tumors).
    In evaluating a chemical's dietary risks for threshold effects, EPA
uses a reference dose (RfD) approach, which involves a number of
considerations including:
     A 'point of departure'(PoD) - the value from a dose-
response curve that is at the low end of the observable data (the no
observed adverse effect level, or NOAEL, the lowest-observed adverse
effect level or LOAEL, or an extrapolated benchmark dose) and that is
the dose serving as the 'starting point' in extrapolating a risk to the
human population;
     An uncertainty factor to address the potential for a
difference in toxic response between humans and animals used in
toxicity tests (i.e., interspecies extrapolation);
     An uncertainty factor to address the potential for
differences in sensitivity in the toxic response across the human
population (for intraspecies extrapolation); and
     The need for an additional safety factor to protect
infants and children, as specified in FFDCA section 408(b)(2)(C).
    EPA uses the chosen PoD to calculate a safe dose or RfD. The RfD is
calculated by dividing the chosen PoD by all applicable safety or
uncertainty factors. Typically in EPA risk assessments, a combination
of safety or uncertainty factors providing at least a hundredfold
(100X) margin of safety is used: 10X to account for interspecies
extrapolation and 10X to account for intraspecies extrapolation.
Further, in evaluating the dietary risks for pesticide chemicals, an
additional safety factor of 10X is presumptively applied to protect
infants and children, unless reliable data support selection of a
different factor. In implementing FFDCA section 408, EPA also
calculates a variant of the RfD referred to as a population adjusted
dose (PAD). The PAD is the RfD divided by any portion of the children's
safety factor that does not correspond to one of the traditional
additional uncertainty/safety factors used in general Agency risk
assessment. The reason for calculating PADs is so that other parts of
the Agency, which are not governed by FFDCA section 408, can, when
evaluating the same or similar substances, easily identify which
aspects of a pesticide risk assessment are a function of the particular
statutory commands in FFDCA section 408. For acute assessments, the
risk is expressed as a percentage of a maximum acceptable dose or the
acute PAD (i.e., the acute dose which EPA has concluded will be
``safe''). As discussed below in Unit V.C., dietary exposures greater
than 100 percent of the acute PAD are generally cause for concern and
would be considered ``unsafe'' within the meaning of FFDCA section
408(b)(2)(B). Throughout this document general references to EPA's
calculated safe dose are denoted as an acute PAD, or aPAD, because the
relevant point of departure for carbaryl is based on an acute risk
endpoint.
    In evaluating a chemical's dietary risk for non-threshold effects,
such as cancer; EPA's default approach is to extrapolate a Q1* from the
dose-response curve as a measure of cancer potency, and then to use
this Q1* value in conjunction with estimated dietary exposure to
estimate the probability of occurrence of additional adverse effects.
The Q1*is the 95th percentile upper confidence limit from a tumor dose
response curve extrapolated using a linear low-dose model. For non-
threshold dietary cancer risks, EPA generally considers cancer risk to
be negligible if the probability of increased cancer cases falls within
the range of 1 in 1 million.
    Animal studies show that carbaryl, like other NMC pesticides,
causes transient, reversible inhibition of cholinesterase activity in
brain, red blood cells, and plasma across all tested routes of
exposure. Developmental toxicity was seen in rats and rabbits treated
with carbaryl during gestation; effects included decreased fetal weight
and incomplete ossification (bone formation). A carbaryl rat
reproductive toxicity study showed decreased pup survival, and a rat
developmental neurotoxicity study showed changes in fetal brain
morphometry. In addition, a comparative cholinesterase study shows that
young animals had increased sensitivity, compared with adults, to
inhibition of brain cholinesterase from carbaryl. EPA used endpoints
from the comparative cholinesterase study to assess human health risk
in both the single chemical risk assessment for carbaryl and in the
cumulative risk assessment for the NMC pesticides. Carbaryl is
considered to be ``likely to be carcinogenic in humans'' based on
tumors in male mice and EPA utilized the Agency default low-dose linear
extrapolation (Q1*) approach to quantify cancer risk.
    2. Estimating human exposure levels. Pursuant to section 408(b) of
the FFDCA, EPA has evaluated carbaryl dietary risks based on
``aggregate

exposure'' to carbaryl. By ``aggregate exposure,'' EPA is referring to
exposure to carbaryl alone by multiple pathways of exposure, including
residues in food and water and exposure from use of carbaryl products
in residential settings. EPA uses available data, together with
assumptions designed to be protective of public health and standard
analytical methods, to produce separate estimates of exposure for a
highly exposed subgroup of the general population, for each potential
pathway and route of exposure. For acute risks, EPA then calculates
potential aggregate exposure and risk by using probabilistic techniques
to combine distributions of potential exposures in the population for
the dietary pathway, and uses single point estimates for the
residential component in calculating aggregate exposure. For dietary
analyses, the relevant sources of potential exposure to carbaryl are
from the ingestion of residues in food and drinking water.
    The Agency uses a combination of monitoring data and predictive
models to evaluate environmental exposure of humans to carbaryl, which
may occur from ingesting carbaryl residues in food or drinking water,
or from using products containing carbaryl in residential settings.
These are described below.
    a. Exposure from food. Data on the residues of carbaryl in foods
are available from a variety of sources. One of the primary sources of
the data comes from federally-conducted surveys, including the
Pesticide Data Program (PDP) conducted by the USDA. Further, market
basket studies, which are typically performed by registrants, can
provide additional residue data. These data generally provide a
characterization of pesticide residues in or on foods consumed by the
U.S. population that closely approximates real world exposures because
they are sampled closer to the point of consumption in the chain of
commerce than field trial data, which are generated to establish the
maximum level of legal residues that could result from maximum
permissible use of the pesticide. In certain circumstances, EPA will
rely on field trial data, as it can provide more accurate exposure
estimates. EPA estimated dietary exposure to carbaryl using residue
data from a variety of sources, including USDA and FDA monitoring and
crop field trial studies. These residue data were refined based on
relevant processing factors. EPA also took into account information on
the extent to which crops which may be treated with carbaryl are
actually so treated.
    EPA uses a computer program, the Dietary Exposure Evaluation Model
(DEEM), and the USDA Food Commodity Intake database (FCID), to estimate
exposure by combining data on human consumption amounts with residue
values in food commodities. DEEM-FCIDTM also compares
exposure estimates to appropriate RfD or PAD values to estimate risk.
EPA uses DEEM-FCIDTM to estimate exposure for the general
U.S. population as well as for 32 subgroups based on age, sex,
ethnicity, and region. DEEM-FCIDTM allows EPA to process
extensive volumes of data on human consumption amounts and residue
levels in making risk estimates. Matching consumption and residue data,
as well as managing the thousands of repeated analyses of the
consumption database conducted under probabilistic risk assessment
techniques, requires the use of a computer.
    DEEM-FCIDTM contains consumption and demographic
information on the individuals who participated in the USDA's Combined
Survey of Food Intake by Individuals (CSFII) in 1994-1996 and 1998. The
1998 survey was a special survey required by the FQPA to supplement the
number of children survey participants. DEEM-FCIDTM also
contains ``recipes'' that convert foods as consumed (e.g., pizza) back
into their component raw agricultural commodities (e.g., wheat from
flour, or tomatoes from sauce, etc.). This is necessary because residue
data are generally gathered on raw agricultural commodities rather than
on finished ready-to-eat food. Data on residue values for a particular
pesticide and the RfD or PADs for that pesticide are inputs to the
DEEM-FCIDTM program to estimate exposure and risk.
    For carbaryl's assessment, EPA used DEEM-FCIDTM to
calculate risk estimates based on a probabilistic distribution. DEEM-
FCIDTM combines the full range of residue values for each
food with the full range of data on individual consumption amounts to
create a distribution of exposure and risk levels. More specifically,
DEEM-FCIDTM creates this distribution by calculating an
exposure value for each reported day of consumption per person
(``person/day'') in USDA's CSFII, assuming that all foods potentially
bearing the pesticide residue contain such residue at the chosen value.
The exposure amounts for the thousands of person/days in the CSFII are
then collected in a frequency distribution. EPA also uses DEEM-
FCIDTM to compute a distribution taking into account both
the full range of data on consumption levels and the full range of data
on potential residue levels in food. Combining consumption and residue
levels into a distribution of potential exposures and risk requires use
of probabilistic techniques.
    Probabilistic analysis is used to predict the frequency with which
variations of a given event will occur. By taking into account the
actual distribution of possible consumption and pesticide residue
values, probabilistic analysis for pesticide exposure assessments
``provides more accurate information on the range and probability of
possible exposure and their associated risk values'' (Ref. 3). In
capsule, a probabilistic pesticide exposure analysis constructs a
distribution of potential exposures based on data on consumption
patterns and residue levels and provides a ranking of the probability
that each potential exposure will occur. People consume differing
amounts of the same foods, including none at all, and a food will
contain differing amounts of a pesticide residue, including none at
all.
    The probabilistic technique that DEEM-FCIDTM uses to
combine differing levels of consumption and residues involves the
following steps:
    (1) Identification of any food(s) that could bear the residue in
question for each person/day in the CSFII;
    (2) Calculation of an exposure level for each of the thousands of
person/days in the CSFII database, based on the foods identified in
Step 1 by randomly selecting residue values for the foods from
the residue database;
    (3) Repetition of Step 2 up to one thousand times for each
person/day; and
    (4) Collection of all of the hundreds of thousands of potential
exposures estimated in Steps  2 and 3 in a frequency
distribution.
    The resulting probabilistic assessment presents a range of
exposure/risk estimates.
    b. Exposure from water. EPA may use field monitoring data and/or
simulation water exposure models to generate pesticide concentration
estimates in drinking water. Monitoring and modeling are both important
tools for estimating pesticide concentrations in water and can provide
different types of information. Monitoring data can provide estimates
of pesticide concentrations in water that are representative of the
specific agricultural or residential pesticide practices in specific
locations, under the environmental conditions associated with a
sampling design (i.e., the locations of sampling, the times of the year
samples were taken, and the frequency by which samples were collected).
Although monitoring data

can provide a direct measure of the concentration of a pesticide in
water, it does not always provide a reliable basis for estimating
spatial and temporal variability in exposures because sampling may not
occur in areas with the highest pesticide use, and/or when the
pesticides are being used and/or at an appropriate sampling frequency
to detect high concentrations of a pesticide that occur over the period
of a day to several days.
    Because of the limitations in most monitoring studies, EPA's
standard approach is to use simulation water exposure models as the
primary means to estimate pesticide exposure levels in drinking water.
EPA's computer models use detailed information on soil properties, crop
characteristics, and weather patterns to estimate water concentrations
in vulnerable locations where the pesticide could be used according to
its label. (69 FR 30042, May 26, 2004). These models calculate
estimated water concentrations of pesticides using laboratory data that
describe how fast the pesticide breaks down to other chemicals and how
it moves in the environment at these vulnerable locations. The modeling
provides an estimate of pesticide concentrations in ground and surface
water. Daily concentrations can be estimated continuously over long
periods of time, and for places that are of most interest for any
particular pesticide.
    EPA relies on models it has developed for estimating pesticide
concentrations in both surface water and ground water. Typically EPA
uses a two-tiered approach to modeling pesticide concentrations in
surface and ground water. If the first tier model suggests that
pesticide levels in water may be unacceptably high, a more ined model
is used as a second tier assessment. For surface water assessments, the
second tier model is actually a combination of two models: The
Pesticide Root Zone Model (PRZM) and the Exposure Analysis Model System
(EXAMS).
    A detailed description of the models routinely used for exposure
assessment is available from the EPA web site: http://www.epa.gov/
oppefed1/models/water/index.htm. These models provide a means for EPA
to estimate daily pesticide concentrations in surface water sources of
drinking water (a reservoir) using local soil, site, hydrology, and
weather characteristics along with pesticide application and
agricultural management practices, and pesticide environmental fate and
transport properties. Consistent with the recommendations of the FIFRA
Science Advisory Panel (SAP), EPA also considers percent cropped area
factors (PCA) which takes into account the potential extent of cropped
areas that could be treated with pesticides in a particular area. The
PRZM and EXAMS models used by EPA were developed by EPA's Office of
Research and Development (ORD), and are used by many international
pesticide regulatory agencies to estimate pesticide exposure in surface
water. EPA's use of the percent cropped area factors and the Index
Reservoir scenario was reviewed by the FIFRA SAP in 1999 and 1998,
respectively (Refs. 4 and 5).
    In modeling potential surface water concentrations, EPA attempts to
model areas of the country that are highly vulnerable to surface water
contamination rather than simply model ``typical'' locations occurring
across the nation. Consequently, EPA models exposures occurring in
small highly agricultural watersheds in different growing areas
throughout the country. The scenarios are designed to capture residue
levels in drinking water from reservoirs with small watersheds with a
large percentage of land use in agricultural production. EPA believes
these assessments are likely reflective of a small subset of the
watersheds across the country that maintain drinking water reservoirs,
representing a drinking water source generally considered to be more
vulnerable to frequent high concentrations of pesticides than most
locations that could be used for crop production.
    When EPA completed the carbaryl Interim Reregistration Eligibility
Decision (IRED)\1\ in June 2003, EPA compared the estimated drinking
water concentrations (EDWCs) of pesticides, from the PRZM/EXAMS model,
with a drinking water level of concern (DWLOC), a value representing
the concentration of a pesticide in drinking water that would represent
the upper limit in light of total aggregate exposure to that pesticide
from food, water, and residential uses of that pesticide. The DWLOC
approach was developed in the mid 1990s as part of EPA's review of
pesticides under FQPA, before the current risk assessment methodologies
became available. EPA now uses the output of daily concentration values
from tier two modeling as an input to DEEM-FCIDTM, which
combines water concentrations with drinking water consumption
information in the daily diet to generate a distribution of exposures
from consumption of drinking water containing pesticide residues. These
results are then used to calculate a probabilistic assessment of the
aggregate human exposure and risk from residues in food and drinking
water.
---------------------------------------------------------------------------

    \1\ Because carbaryl is a member of the NMC group of pesticides,
which share a common mechanism of toxicity, EPA was unable to
complete the carbaryl Reregistration Eligibility Decision (RED)
before completion of the NMC cumulative risk assessment in September
2007.
---------------------------------------------------------------------------

    EPA also considers available surface water monitoring data,
including data from the US Geological Survey (USGS) National Water
Quality Assessment Program (NAWQA), in conducting drinking water
assessments. For the 2007 carbaryl RED, EPA considered data from a
variety of sources, including NAWQA, the joint USGS-EPA Mini Pilot
Monitoring Program, Washington and California state monitoring data,
and registrant voluntary water monitoring study measuring carbaryl in
targeted community water systems associated with watersheds having high
carbaryl use.
    c. Residential exposures. Generally, in assessing residential
exposure to pesticides EPA relies on its Standard Operating Procedures
(SOPs) for Residential Exposure Assessment and subsequent amendments
(Refs. 6, 7, and 8). The Residential SOPs establish the approaches used
for estimating application and post-application exposures in a
residential setting. SOPs have been developed for many common exposure
scenarios including pesticide treatment of lawns, garden plants, trees,
swimming pools, pets, and indoor surfaces including crack and crevice
treatments. The SOPs are based on existing monitoring and survey data
including information on activity patterns, particularly for children.
Where available, EPA relies on pesticide-specific data in estimating
residential exposures. Although limited carbaryl specific data were
available at the time the carbaryl IRED was completed, additional data
were submitted in response to the 2005 Data Call-In (DCI) for carbaryl.
These data were reviewed and incorporated into the revised residential
risk assessment used to support the final carbaryl RED. Residential
exposure from carbaryl was estimated using EPA's Residential SOPs (as
amended) as well as a turf dissipation study for carbaryl which
quantified turf transferable residues after carbaryl application to
turf and other monitoring data available to the Agency (e.g., residue
decline studies on garden crops).
    3. Risk characterization. The final step in the risk assessment is
risk characterization. In this step, EPA combines information from the
first three steps (hazard identification, level of concern/dose-
response analysis, and human exposure assessment) to

quantitatively estimate the risks posed by a pesticide. Separate
characterizations of risk are conducted for different durations of
exposure. Additionally, separate and, where appropriate, aggregate
characterizations of risk are conducted for the different routes of
exposure (dietary and non-dietary).
    For threshold risks, EPA estimates risk in one of two ways. Where
EPA has calculated an RfD/PAD, risk is estimated by expressing human
exposure as a percentage of the RfD/PAD. Exposures lower than 100
percent of the RfD/PAD are generally not of concern. Alternatively, EPA
may express risk by dividing the estimated human exposure into the PoD
to derive a margin of exposure (MOE). The MOE is compared with a level
of concern, which is the product of all applicable uncertainty/safety
factors. In contrast to the RfD/PAD approach, the higher the MOE, the
lower the risk concern for the pesticide. Accordingly, if the level of
concern is 100, MOEs equal to or exceeding 100 would generally not be
of concern.
    As a conceptual matter, the RfD/PAD and MOE approaches are
fundamentally equivalent. For a given risk and given exposure of a
pesticide, if exposure to a pesticide were found to be acceptable under
an RfD/PAD analysis it would also pass under the MOE approach, and
vice-versa. However, for any specific pesticide, risk assessments for
different exposure durations or routes may yield different results.
This is a function not of the choice of the RfD/PAD or MOE approach but
of the fact that the levels of concern and the levels of exposure may
differ depending on the duration and route of exposure.
    For non-threshold risks (generally, cancer risks), EPA uses the
slope of the dose-response curve for a pesticide in conjunction with an
estimation of human exposure to that pesticide to estimate the
probability of occurrence of additional adverse effects. For non-
threshold cancer risks, EPA generally considers cancer risk to be
negligible if the probability of increased cancer cases falls within
the range of 1 in 1 million. Risks exceeding values within that range
would raise a risk concern.

C. Science Policy Considerations

    1. EPA policy on the children's safety factor. As the above brief
summary of EPA's risk assessment practice indicates, the use of safety
factors plays a critical role in the process. This is true for
traditional 10X safety factors to account for potential differences
between animals and humans when relying on studies in animals (inter-
species safety factor) and potential differences among humans (intra-
species safety factor) as well as the FQPA's additional 10X children's
safety factor.
    In general, Section 408 of FFDCA provides that EPA shall apply an
additional 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 that a different margin of safety will be safe
for infants and children. Margins of safety are incorporated into EPA
assessments either directly through use of a margin of exposure
analysis or through using uncertainty (safety) factors in calculating a
dose level that poses acceptable risk to humans.
    In applying the children's safety factor provision, EPA has
interpreted the statutory language as imposing a presumption in favor
of applying an additional 10X safety factor (Ref. 9). Thus, EPA
generally refers to the additional 10X factor as a presumptive or
default 10X factor. EPA has also made clear, however, that the
presumption can be overcome if reliable data demonstrate that a
different factor is safe for children (Id.). In determining whether a
different factor is safe for children, EPA focuses on the three factors
listed in section 408(b)(2)(C) - the completeness of the toxicity
database, the completeness of the exposure database, and potential pre-
and post-natal toxicity. In examining these factors, EPA strives to
make sure that its choice of a safety factor, based on a weight-of-the-
evidence evaluation, does not understate the risk to children. (Id.).
    When EPA evaluated the carbaryl toxicological database in 2003 to
determine the appropriate FQPA Safety Factor for use in the IRED,
available studies included rat and rabbit teratology (developmental
toxicity) studies, a rat developmental neurotoxicity study, a rat
reproductive toxicity study, a 4-week dermal rat study, acute and
subchronic neurotoxicity screening studies, and a chronic oral dog
study (Ref. 10). Based on the weight of the evidence as evaluated in
2003, the FQPA Safety Factor was determined to be 3X due to the lack of
a NOAEL in the chronic dog study. This was what the weight of the
evidence showed in 2003.
    The science has advanced since 2003; additional information on
pharmacokinetics as well as additional acute cholinesterase data have
become available for carbaryl and other NMCs. Due to the rapid recovery
of cholinesterase activity, chronic exposure is no longer considered to
be a concern for carbaryl. As the science has advanced, science policy
has also evolved. As EPA acquired developmental neurotoxicity and
comparative cholinesterase data on the NMCs, it became apparent that
comparative cholinesterase studies measuring red blood cell (RBC) and
brain cholinesterase inhibition in both maternal and young animals
(postnatal day 11 (PND11) and postnatal day 17 (PND17)) were a more
accurate predictor of age-related sensitivity than developmental
neurotoxicity studies measuring behavioral and histopathological
changes. Therefore, EPA informed registrants that, in the absence of
comparative cholinesterase data for each pesticide, a 10X FQPA Safety
Factor would be applied to that pesticide in the NMC cumulative risk
assessment. If comparative cholinesterase data were available, EPA used
a data derived approach for the FQPA Safety Factor by comparing the
benchmark dose (BMD) at the 10% inhibition level for either brain or
RBC acetyl cholinesterase inhibition between maternal animals and the
juvenile animals (typically PND11).
    2. EPA Policy on cholinesterase inhibition as a regulatory
endpoint. Cholinesterase inhibition is a disruption of the normal
process in the body by which the nervous system chemically communicates
with muscles and glands. Communication between nerve cells and a target
cell (i.e., another nerve cell, a muscle fiber, or a gland) is
facilitated by the chemical, acetylcholine. When a nerve cell is
stimulated it releases acetylcholine into the synapse (or space)
between the nerve cell and the target cell. The released acetylcholine
binds to receptors in the target cell, stimulating the target cell in
turn. As EPA has explained, ``the end result of the stimulation of
cholinergic pathway(s) includes, for example, the contraction of smooth
(e.g., in the gastrointestinal tract) or skeletal muscle, changes in
heart rate or glandular secretion (e.g., sweat glands) or communication
between nerve cells in the brain or in the autonomic ganglia of the
peripheral nervous system.'' (Ref. 11 at 10).
    Acetylcholinesterase (AChE) is an enzyme that breaks down
acetylcholine and terminates its stimulating action in the synapse
between nerve cells and target cells. When AChE is inhibited,
acetylcholine builds up prolonging the stimulation of the target cell.
This excessive stimulation potentially results in a broad range of
adverse effects on many bodily functions. Depending on

the degree of inhibition these effects can be serious, even fatal.
    EPA's cholinesterase inhibition policy statement explains EPA's
approach to evaluating the risks posed by cholinesterase-inhibiting
pesticides such as carbaryl. (Id). The policy focuses on three types of
effects associated with cholinesterase-inhibiting pesticides that may
be assessed in animal and human toxicological studies: (1)
physiological and behavioral/functional effects; (2) cholinesterase
inhibition in the central and peripheral nervous system; and (3)
cholinesterase inhibition in red blood cells and blood plasma. The
policy discusses how such data should be integrated in deriving an
acceptable dose (RfD/PAD) for a cholinesterase-inhibiting pesticide.
    Clinical signs or symptoms of cholinesterase inhibition in humans,
the policy concludes, provide the most direct evidence of the adverse
consequences of exposure to cholinesterase-inhibiting pesticides.
Nonetheless, as the policy notes, due to strict ethical limitations,
studies in humans are ``quite limited.'' (Id. at 19). Although animal
studies can also provide direct evidence of cholinesterase inhibition
effects, animal studies cannot easily measure cognitive effects of
cholinesterase inhibition such as effects on perception, learning, and
memory. For these reasons, the policy recommends that ``functional data
obtained from human and animal studies should not be relied on solely,
to the exclusion of other kinds of pertinent information, when weighing
the evidence for selection of the critical effect(s) that will be used
as the basis of the RfD or RfC.'' (Id. at 20).
    After clinical signs or symptoms, cholinesterase inhibition in the
nervous system provides the next most important endpoint for evaluating
cholinesterase-inhibiting pesticides. Although cholinesterase
inhibition in the nervous system is not itself regarded as a direct
adverse effect, it is ``generally accepted as a key component of the
mechanism of toxicity leading to adverse cholinergic effects.'' (Id. at
25). As such, the policy states that it should be treated as ``direct
evidence of potential adverse effects'' and ``data showing this
response provide valuable information in assessing potential hazards
posed by anticholinesterase pesticides.'' (Id.). AChE inhibition in
brain and the peripheral nervous system is the initial adverse
biological event which results from exposure to NMC pesticides, such as
carbaryl, and with sufficient levels of inhibition leads to other
effects. Thus, AChE inhibition provides the most appropriate effect to
use in risk extrapolation for derivation of RfDs and PADs. Protecting
against AChE inhibition ensures that the other adverse effects
mentioned above do not occur.
    In summary, EPA uses a weight of evidence approach to determine the
toxic effect that will serve as the appropriate PoD for a risk
assessment for AChE inhibiting pesticides, such as carbaryl (Id). The
neurotoxicity that is associated with these pesticides can occur in
both the central (brain) and the peripheral nervous system. In its
weight of the evidence analysis, EPA reviews data, such as AChE
inhibition data from the brain, peripheral tissues and blood (e.g., RBC
or plasma), in addition to data on clinical signs and other functional
effects related to AChE inhibition. Based on these data, EPA selects
the most appropriate effect on which to regulate; such effects can
include clinical signs of AChE inhibition, central or peripheral
nervous tissue measurements of AChE inhibition or RBC AChE measures
(Id). Although RBC AChE inhibition is not adverse in itself, it is a
surrogate for inhibition in peripheral tissues when peripheral data are
not available. As such, RBC AChE inhibition provides an indirect
indication of adverse effects on the nervous system (Id.). Due to
technical difficulties regarding dissection of peripheral nerves and
the rapid nature of carbaryl toxicity, measures of AChE inhibition in
the peripheral nervous system are very rare for NMC pesticides. For
these reasons, other state and national agencies such as California,
Washington, Canada, the European Union, as well as the World Health
Organization (WHO), all use blood measures in human health risk
assessment and/or worker safety monitoring programs.
    3. Benchmark dose. EPA has relied on a benchmark dose approach for
deriving the PoD from the available rat toxicity studies (Ref. 12). A
benchmark dose, or BMD, is a point estimate along a dose-response curve
that corresponds to a specific response level. For example, a
BMD10 represents a 10% change from the background or typical
value for the response of concern. Generically, the direction of change
from background can be an increase or a decrease depending on the
biological parameter and the chemical of interest. In the case of
carbaryl, inhibition of AChE is the toxic effect of concern. Following
exposure to carbaryl, the normal biological activity of the AChE enzyme
is decreased (i.e., the enzyme is inhibited). Thus, when evaluating
BMDs for carbaryl, the Agency is interested in a decrease in AChE
activity compared to normal activity levels, which are also termed
``background'' levels. Measurements of ``background'' AChE activity
levels are usually obtained from animals in experimental studies that
are not treated with the pesticide of interest (i.e., ``negative
control'' animals).
    In addition to the BMD, a ``confidence limit'' was also calculated.
Confidence limits express the uncertainty in a BMD that may be due to
sampling and/or experimental error. The lower confidence limit on the
dose used as the BMD is termed the BMDL, which the Agency uses as the
PoD. Use of the BMDL for deriving the PoD rewards better experimental
design and procedures that provide more precise estimates of the BMD,
resulting in tighter confidence intervals. Use of the BMDL also helps
ensure with high confidence (e.g., 95% confidence) that the selected
percentage of AChE inhibition is not exceeded. From the PoD, EPA
calculates the RfD and aPAD.
    Numerous scientific peer review panels over the last decade have
supported the Agency's application of the BMD approach as a
scientifically supportable method for deriving PoDs in human health
risk assessment, and as an improvement over the historically applied
approach of using NOAELs or LOAELs. The NOAEL/LOAEL approach does not
account for the variability and uncertainty in the experimental
results, which are due to characteristics of the study design, such as
dose selection, dose spacing, and sample size. With the BMD approach,
all the dose response data are used to derive a PoD. Moreover, the
response level used for setting regulatory limits can vary based on the
chemical and/or type of toxic effect (Refs. 12, 13, 14, and 15).
Specific to carbaryl and other NMCs, the FIFRA SAP has reviewed and
supported the statistical methods used by the Agency to derive BMDs and
BMDLs on two occasions, February 2005 and August 2005 (Refs. 14 and
15).

IV. Carbaryl Tolerances

A. Regulatory Background

    Carbaryl is a carbamate insecticide and molluscide that was first
registered in 1959 for use on cotton. Carbaryl has many trade names,
but is most commonly known as Sevin[reg]. In 1980, the Agency published
a position document summarizing its conclusions from a Special Review
of carbaryl, and concluded that risk concerns, particularly those
related to teratogenicity, did not warrant cancellation of the
registration for carbaryl. A Registration Standard, issued for carbaryl
in 1984 and revised

in 1988, described the terms and conditions for continued registration
of carbaryl. At the time carbaryl was assessed for purposes of
reregistration, carbaryl was registered for use on over 400
agricultural and non-agricultural use sites, and there were more than
140 tolerances for carbaryl in the Code of Federal Regulations (40 CFR
180.169). For example, carbaryl was registered for domestic outdoor
uses on lawns and gardens, and indoors in kennels and on pet sleeping
quarters. It was also registered for direct application to cats and
dogs (collar, powder, and dip) to control fleas and ticks.
    EPA completed an IRED for carbaryl on June 30, 2003 (2003 IRED).
The Agency amended the IRED on October 22, 2004 (2004 Amended IRED),
and published a formal Notice of Availability for the document, which
provided for a 60-day public comment period (Ref. 16). EPA received
numerous comments on the carbaryl IRED, including the NRDC petition
requesting that EPA cancel all carbaryl registrations and revoke all
tolerances. The Agency published a Notice of Receipt for the petition
in the Federal Register, which provided a public comment period.
Petition to Revoke or Modify Tolerances Established for Carbaryl;
Notice of Availability, 70 FR 16281 (March 30, 2005). The mitigation
detailed in the 2004 Amended IRED for residential uses included:
canceling liquid broadcast applications to home lawns pending EPA
review of pharmacokinetic data to refine post-application risk
estimates; home garden/ornamental dust products must be packaged in
ready-to-use shaker can containers, with no more than 0.05 lbs. active
ingredient per container; cancellation of the following uses and
application methods: all pet uses (dusts and liquids) except collars,
aerosol products for various uses, belly grinder applications of
granular and bait products for lawns, hand applications of granular and
bait products for ornamentals and gardens.
    On March 9, 2005, EPA issued a cancellation order for the liquid
broadcast use of carbaryl on residential turf to address post-
application risk to toddlers (Ref. 17). In March 2005, EPA also issued
generic and product-specific DCIs for carbaryl. The carbaryl generic
DCI required several studies of the active ingredient carbaryl,
including additional toxicology, worker exposure monitoring, and
environmental fate data. The product-specific DCI required acute
toxicity and product chemistry data for all pesticide products
containing carbaryl; these data are being used for product labeling.
EPA has received numerous studies in response to these DCIs, and, where
appropriate, these studies were considered in the tolerance
reassessment.
    In response to the DCIs, many carbaryl registrants chose to
voluntarily cancel their carbaryl products, rather than revise their
labels or conduct studies to support these products. EPA published a
notice of receipt of this request in the Federal Register on October
28, 2005 (70 FR 62112), followed by a cancellation order issued on July
3, 2006. One technical registrant, Burlington Scientific, chose to
cancel their technical product, leaving Bayer CropScience (Bayer) as
the sole technical registrant for carbaryl. Approximately two-thirds of
all of the carbaryl products registered at the time of the 2003 IRED
have been canceled through this process.
    In addition, Bayer, the sole remaining technical registrant
responsible for developing data, requested waivers of required exposure
monitoring or residue studies because these use scenarios are not on
any Bayer technical or product labels or were to be deleted from Bayer
labels: carbaryl use in or on pea and bean, succulent shelled (subgroup
6B); millet; wheat; pre-plant root dip for sweet potato; pre-plant root
dip/drench fpr nursery stocks, vegetable transplants, bedding plants,
and foliage plants; use of granular formulations on leafy vegetables
(except Brassica); ultra low volume (ULV) application for adult
mosquito control; and dust applications in agriculture.
    Bayer subsequently requested that all of their carbaryl
registrations bearing any of these uses be amended to delete these
uses; EPA published a Notice of receipt of this request in the Federal
Register on August 20, 2008 (73 FR 49184), and plans to approve Bayer's
request and issue a final order amending these registrations at the end
of the comment period for the Notice. As a consequence, EPA has
notified all affected registrants that these uses and application
methods must be deleted from their carbaryl product labels. EPA has
identified thirty four (34) product labels from 14 registrants (other
than Bayer) bearing these end uses. All of these registrants have
requested that their affected carbaryl product registrations be amended
to delete these uses. EPA published a Notice of receipt of these
requests in the Federal Register on August 20, 2008 and will publish a
second Notice of Receipt of these requests on or about October 8, 2008.
    In June 2006, EPA determined that the uses associated with 120 of
the existing carbaryl tolerances are not significant contributors to
the overall NMC cumulative risk and as a result these tolerances will
have no effect on the retention or revocation of other NMC tolerances.
Therefore, EPA considered these 120 tolerances for carbaryl as
reassessed on June 29, 2006, and posted this decision on the internet
site. (See http://www.epa.gov/pesticides/cumulative/carbamates_
commodity.pdf).
    Carbaryl is a member of the NMC class of pesticides which share a
common mechanism of toxicity by affecting the nervous system via
cholinesterase inhibition. Specifically, carbaryl is a reversible
inhibitor of AChE. A cumulative risk assessment, which evaluates
exposures based on a common mechanism of toxicity, was conducted to
evaluate risk from food, drinking water, residential use, and other
non-occupational exposures resulting from registered uses of NMC
pesticides, including carbaryl.
    In late November 2006, EPA received data from a carbaryl
comparative cholinesterase study, conducted to determine the
comparative sensitivity of adults and offspring to cholinesterase
inhibition by carbaryl. These data were used to revise the FQPA Safety
Factor for carbaryl for the NMC cumulative risk assessment and to
select new toxicology endpoints (PoDs) for the risk assessment. The
Agency determined that it was appropriate to use the new FQPA Safety
Factor and revised PoDs in both the NMC cumulative risk assessment and
the carbaryl-specific human health risk assessment. Because this
necessitated a revision of the carbaryl human health aggregate risk
assessment, EPA also considered additional new data generated in
response to the DCI, new methodologies, and other new information in
performing its most recent assessment of carbaryl and in responding to
this Petition. EPA has thus, in effect, revised the carbaryl single
chemical assessment in response to the issues raised during the public
comment process as well as based upon more recent data and analytical
methods.
    On September 26, 2007, EPA issued the NMC cumulative risk
assessment. EPA concluded that the cumulative risks associated with the
NMC pesticides meet the safety standard set forth in section 408(b)(2)
of the FFDCA, provided that the mitigation specified in the NMC
cumulative risk assessment is implemented, such as cancellation of all
uses of carbofuran, termination of methomyl use on grapes, etc. EPA has
therefore terminated the tolerance reassessment process under 408(q) of

the FFDCA. (See Ref. 18 for additional information).
    In conjunction with the NMC cumulative risk assessment, EPA
completed a RED for carbaryl on September 24, 2007 and issued this RED
on October 17, 2007 with a formal Notice of Availability in the Federal
Register (72 FR 58844). In addition to relying on the NMC cumulative
risk assessment to determine that the cumulative effects from exposure
to all NMC residues, including carbaryl, was safe, the carbaryl RED
relied upon the revised assessments and the mitigation that had already
been implemented (e.g., cancellation of pet uses except for collars).
In addition, the RED included additional mitigation with respect to
granular turf products for residential use; namely, that product labels
direct users to water the product in immediately after application.
Subsequently, on August 25, 2008, EPA completed an addendum to the
Carbaryl RED incorporating the results of a revised occupational risk
assessment and modified mitigation measures for the protection of
workers. Elsewhere in this issue of the Federal Register EPA is
announcing the availability of the amendments to the Carbaryl RED.

B. FFDCA Tolerance Reassessment and FIFRA Pesticide Reregistration

    As required by the Food Quality Protection Act of 1996, EPA
reassessed the safety of the carbaryl tolerances under the safety
standard established in the FQPA. In the September 2007 RED for
carbaryl, EPA evaluated the human health risks associated with all
currently registered uses of carbaryl and determined that there is a
reasonable certainty that no harm will result from aggregate non-
occupational exposure to the pesticide chemical residue. In making this
determination, EPA considered dietary exposure from food and drinking
water and all other non-occupational sources of pesticide exposure for
which there is reliable information (Ref. 18). The Agency has concluded
that with the adoption of the risk mitigation measures identified in
the NMC cumulative risk assessment, all of the tolerances for carbaryl
meet the safety standard as set forth in section 408(b)(2)(D) of the
FFDCA. Therefore, the tolerances established for residues of carbaryl
in/on raw agricultural commodities were considered reassessed as safe
under section 408(q) of FFDCA, as amended by FQPA, in September 2007.
These findings satisfied EPA's obligation to review the carbaryl
tolerances under the FQPA safety standard.
    To implement the carbaryl tolerance reassessment, EPA commenced
with rulemaking in 2008. The Agency published a Notice of proposed
tolerance actions in the May 21, 2008 Federal Register (73 FR 29456).
This proposed rule provided for a 60 day public comment period. No
comments relevant to carbaryl tolerances were received and EPA
published a Notice of final tolerance actions in the September 10, 2008
Federal Register (73 FR 52607). This rule codifies the carbaryl
tolerances in 40 CFR 180.169.

V. The Petition to Revoke Tolerances

    NRDC filed a petition dated January 10, 2005 (Petition),
requesting, among other things, that EPA cancel all carbaryl
registrations and revoke all carbaryl tolerances (Ref. 1). In response
to EPA's publication of the Petition pursuant to section 408(d) of the
FFDCA, NRDC resubmitted its Petition and earlier comments in support of
its Petition. (See Docket ID EPA-HQ-OPP-2005-0077-0066).
    It should be noted that NRDC's January 10, 2005 submission is in
the form of comments on and requests for changes to the Carbaryl
Interim Reregistration Eligibility Decision published in the Federal
Register on October 27, 2004, 70 FR 62663; (Ref. 16). Nonetheless, in
the introduction to the comments, NRDC included a statement that NRDC
is also petitioning the Agency to revoke all carbaryl tolerances. Among
other things, NRDC raises issues with the dietary assessment and in
particular its drinking water assessment that supported the 2004 IRED
decision. NRDC also raises concerns about the data surrounding EPA's
selection of a children's safety factor. NRDC's petition also includes
some generic disagreements with how EPA conducts its assessments.

VI. Public Comment

    In response to that portion of NRDC's petition seeking revocation
of the carbaryl tolerances, EPA published notice of the Petition for
comment on March 30, 2005 (70 FR 16281). EPA received approximately
5,230 comments in support of the Petition. The vast majority of these
comments followed an identical or similar format expressing the
commenters support for the Petition in general terms. These commenters
uniformly protested the Agency's decision to continue allowing the use
of carbaryl ``a chemical [EPA] consider[s] likely to cause cancer.'' As
a preliminary note, although the Agency considers carbaryl to have the
potential to cause cancer, exposure to carbaryl residues is so low that
the actual risk of cancer from carbaryl is negligible. EPA is generally
not concerned about cancer risks at or below the range of 1 x
10-6, or 1 in a million. For carbaryl, the dietary cancer
risk from residues in food and drinking water is estimated to be 3 x
10-8, or 3 in 10 million. The estimated cancer risk from
exposure to carbaryl in products used in a residential setting range
from 1 x 10-8 to 10-13 (from 1 in 10 million to 1
in 10 trillion). Because EPA considers carbaryl to be a non-threshold
carcinogen, the Agency uses the conservative, default linear low-dose
linear method to quantify cancer risk. Even using this conservative
approach to evaluate potential cancer risk from food, drinking water,
and residential uses of carbaryl, EPA has not identified any cancer
risks of concern.
    Of the subset of comments not based upon a form letter, most
related to ecological issues and in particular toxicity to bees and
apple thinning uses. These comments are not relevant to the requested
revocation of pesticide tolerances. EPA is responding to the Petition
insofar as it seeks the cancellation of all carbaryl registrations
separately and, therefore, these comments are not directly relevant
here. One commenter, Bayer, the sole technical product registrant,
submitted comments that purport to address all of the issues raised by
NRDC (Ref. 19). In any event, these comments as a whole did not add any
new information pertaining to whether the tolerances were in compliance
with the FFDCA. Comments on the specific claims by NRDC are summarized
in Unit VII immediately following the summary of NRDC's claim but prior
to EPA's response to the claim.

VII. Ruling on Petition

    This Order addresses NRDC's petition to revoke carbaryl tolerances.
As noted above, this ``Petition'' was included as part of NRDC's
comments on the carbaryl IRED. Thus, the Petition contains a number of
comments that are just that, comments, and that do not provide a basis
upon which to either cancel all carbaryl registrations or revoke all
carbaryl tolerances. Where those comments are directly related to
suggestions that the carbaryl tolerances do not meet the safety
standard in section 408 of the FFDCA, the Agency has tried to address
those comments in this petition response. However, EPA has not
attempted to respond to every comment or suggestion for improvement
made in NRDC's filing.
    EPA has, to the extent possible, construed NRDC's comments as
asserting various grounds as to why the carbaryl tolerances do not meet
the

FQPA safety standard and should be revoked. EPA has divided NRDC's
grounds for revocation into four categories - toxicology; dietary
exposure; residential exposure; and risk characterization - and
addressed separately each claim under these categories. Each specific
claim of NRDC is summarized in Unit VII immediately prior to EPA's
response to the claim.
    This Order also constitutes a response to a petition dated November
26, 2007, to cancel carbaryl pet collar registrations submitted as part
of NRDC's comments on the NMC cumulative assessment (NMC Petition)
(Ref. 2). EPA's response to NRDC's petition to cancel pet collar
registrations is addressed here because the basis for the petition to
cancel pet collars rests on issues related to EPA's assessment of
cumulative effects under the FFDCA.
    EPA has not addressed claims that concern carbaryl uses that have
been canceled, or application methods that have been discontinued since
the time of the Petition. Nor is EPA addressing claims that concern
carbaryl uses for which the registrant(s) has requested that the use be
deleted or registration cancelled pursuant to section 6(f) of FIFRA.
These include the liquid broadcast use of carbaryl on residential lawns
and turf, cancelled in March 2005 (Ref. 17), and several other uses and
application methods which have been or are in the process of
cancellation because the registrants are not supporting these uses and
application methods with the necessary data (73 FR 49184, August 20,
2008). The following carbaryl uses are in the process of being
cancelled: wheat, millet, and fresh/succulent beans and peas (crop
subgroup 6B); use of carbaryl drench or dip treatments of seedlings or
seed pieces, dust formulations in agricultural crops, granular
applications to leafy vegetables (except Brassica), direct applications
of carbaryl (except for flea collars) to domestic animals (including
dogs, cats, and other pets), and all indoor applications. Carbaryl
registrations are also being amended to discontinue the following
application methods: drenching dipping, hand held fogger, mosquito
adulticide ULV, power backpack sprayer, and tree injection.

A. Dietary Exposure Issues

    1. Revised dietary exposure and risk assessment. NRDC's petition
challenges some aspects of EPA's 2003 proposed dietary exposure and
risk assessment of carbaryl (Ref. 1 at 16-20). EPA has since updated
its dietary exposure and risk assessment. These revisions were
incorporated in and provided the basis for the RED. The main changes in
the revised assessment include: (1) Use of the half-life value for
carbaryl from a study that measures how quickly carbaryl degrades in an
aerobic aquatic environment; (2) inclusion of updated percent crop
treated data for evaluation of dietary exposure from residues in food;
(3) inclusion of a comprehensive review of recent surface water
monitoring data, including an investigation into the high carbaryl
detection in groundwater reported in the 2003 IRED; (4) incorporation
of the most recent food residue data from USDA's PDP; and (5) inclusion
of drinking water exposure modeling and monitoring data for
agricultural and nonagricultural uses of carbaryl. In addition, in a
change from the 2003 assessment, the revised risk assessment did not
evaluate dietary risk for long term (> 6 months) and chronic exposure
to carbaryl due to the rapid reversibility of cholinesterase
inhibition, the toxicological endpoint of concern. Specifically, recent
data for carbaryl and the other NMCs show that cholinesterase
inhibition is reversible, with recovery in less than 24 hours. Because
the acute exposure from carbaryl is the main duration of concern, EPA
determined that a chronic assessment is not appropriate for carbaryl.
    These revisions effectively address NRDC's concerns and EPA is not
reopening the issues here. Nonetheless, EPA is providing more specific
information concerning the revised risk assessment in the context of
the specific issues raised by NRDC.
    2. Drinking water assessment--a. NRDC's claims. NRDC criticizes the
Agency's drinking water assessment because it only considered
agricultural sources. NRDC urged EPA to include all available
information in its surface water assessment, including non-agricultural
sources (Ref. 1 at 16). NRDC further notes that the drinking water
levels of comparison (DWLOCs) ``exceeds acceptable levels.'' (Ref. 1 at
16). NRDC disagrees with EPA's conclusion that the DWLOC was
nonetheless acceptable because the modeling is overly conservative and
that actual concentrations of carbaryl in drinking water are likely to
be ``much lower.'' NRDC faults the Agency for not defining the
magnitude of ``much lower'' and not providing any support for this
contention. In particular, NRDC argues that the modeling estimates are
actually in agreement with some of the monitoring data, and therefore
EPA should accept the modeling estimates as an accurate indicator of
exposure. Specifically, NRDC argues that peak modeling estimates from
Florida citrus use (646 ppb) match monitoring data from a well in New
York (610 ppb), and therefore EPA should accept the modeling estimates
as an accurate indicator of exposure. NRDC further argues that the
Agency's rationale for concluding that the models overestimate actual
concentrations in surface water is faulty.
    b. Public comments. In its comments, Bayer took issue with NRDC's
characterization that the monitoring data are in agreement with the
model calculations, based upon a detection of 610 ppb in a well in New
York and a maximum concentration value of 6.5 ppb in the USGS NAWQA
data. Bayer argues that comparing an isolated ground water finding with
predicted concentrations in surface water is scientifically
inappropriate because of the different transport processes in ground
water as compared to surface water. Bayer characterizes the ground
water detection in NY as anomalous and notes that it has not been
investigated or confirmed, and argues that it is not likely to be the
result of normal movement though the soil.
    Further, Bayer submitted a voluntary drinking water monitoring
study for carbaryl, Surface Water Monitoring for Residue of Carbaryl in
High Use Areas in the United States: Final Report (MRID 45788101).
Bayer defends its drinking water study, stating that it was targeted to
community water systems having watersheds with high carbaryl use and
that showed lower concentrations than the NAWQA data. Bayer further
argues that NRDC's assertion that monitoring can be spotty and is not
designed to coincide with high use sites, seasonal application times,
watershed characteristics, and urban and agricultural methods is
misplaced. Bayer asserts that the monitoring program was targeted and
did focus on high use sites, with a sampling program tailored to the
application times, and covered both agricultural and non-agricultural
uses.
    Bayer also argues that the modeling is a worst case scenario and
gives several reasons why EPA's model can overestimate movement of
surface water, including assumptions regarding use intensity (100% of
field treated at maximum rates for the maximum number of times). Bayer
then asserts that the worst-case predictions are not confirmed by
monitoring data ``specifically designed to capture high use areas and
application times.'' (Ref. 19 at 5).
    Another commenter from the Department of Entomology, Virginia Tech,
notes that while NRDC complains that EPA makes assumptions in its risk

models, NRDC makes questionable assumptions of its own; namely, that
EPA's model is more reliable than actual monitoring data. Similarly,
NRDC emphasizes that most acreage is treated, implying that most acres
received the full allowable rate. However, although carbaryl is allowed
to be applied to apples during the growing season, apple growers use
carbaryl mainly as a chemical thinner, which occurs early in the season
and is much less likely to cause harvest residues. Other commenters
(apple growers) submitted similar comments regarding the actual use and
that the use of carbaryl for thinning is not likely to result in
residues at harvest time as well as the importance of carbaryl for
chemical thinning.
    Another commenter from the University of Florida asserts that the
acute drinking water concern is driven by Florida modeling, based upon
a 38% crop treated assumption. According to the commenter, actual use
in Florida is ``probably closer'' to one tenth of that amount. Again,
according to the commenter, the National Agricultural Statistics
Service (NASS) 2003 fruit data report percent crop treated amounts of
3% for Florida and 5% for grapefruit nationally. The commenter takes
issue with NRDC's claim that the greater than 600 ppb spike in New York
``conforms'' to the results from the modeling. In so doing, the
commenter asserts that carbaryl in New York degrades much slower than
in Florida. The commenter then implies that it is significant that
there are no Florida monitoring values that were in the hundred parts
per billion concentration range.
    c. EPA's response. EPA has addressed NRDC's concerns in the revised
drinking water assessments supporting the carbaryl RED, which includes
all available information including surface water monitoring data, new
environmental fate data, and other new information and methodologies.
EPA incorporated new half-life data from an aerobic aquatic metabolism
study, regional percent cropped area factors, and the mitigation
required in the carbaryl IRED into modeled estimates of carbaryl levels
in surface water. In addition, the Agency used the PRZM-EXAMS model to
generate a distribution of approximately 11,000 values, representing
daily peak values over 30 years. This data set was used to create water
residue data files for use in DEEM-FCIDTM. The range of
annual peak water values was 13 to 108 parts per billion (ppb) over 30
years (Ref. 20 for further details of EPA's refined drinking water
modeling). EPA incorporated this distribution of drinking water values
directly into the exposure component of the dietary assessment, using
the DEEM-FCIDTM model. EPA also incorporated drinking water
consumption data and reported body weights from the CSFII into the
exposure assessment.
    As mentioned above, the carbaryl drinking water assessment is no
longer based upon the DWLOC approach. EPA officially withdrew the
science policy paper describing the DWLOC approach on August 1, 2007
(72 FR 42082). In addition, EPA believes that the new approach is more
protective of sensitive population subgroups, including infants and
children, than the DWLOC approach used in the carbaryl IRED.
    Although EPA did not model nonagricultural use of carbaryl, the
Agency considered these uses in the process of evaluating all available
water monitoring data for carbaryl for the 2007 carbaryl RED. EPA
reviewed the most recent surface water monitoring data for carbaryl in
urban and suburban areas for both the carbaryl IRED and the RED.
Specifically, EPA considered data from NAWQA, the joint USGS-EPA Mini
Pilot Monitoring Program, Washington and California state monitoring
data, and a registrant voluntary water monitoring study measuring
carbaryl in targeted community water systems associated with watersheds
having high carbaryl use. The Agency also considered California
monitoring data targeted to urban use of pesticides (Ref. 21).
    EPA has also obtained additional information on the groundwater
monitoring value of 610 micrograms/liter ([mu]g/L) from Suffolk County
New York reported in the carbaryl IRED. Because this value was
significantly higher than any other monitoring values from ground or
surface water, EPA contacted the Suffolk County government for more
information about this particular groundwater sample. The sample
associated with that concentration (the actual concentration was 61,000
[mu]g/L, not 610 [mu]g/L) was taken from a sump at a pesticide mixer/
loader site as part of a pesticide spill investigation, not from a
groundwater monitoring well. Therefore, this value should not have been
reported in the Suffolk County water quality database (Suffolk County
Department of Health 2007, personal communication); EPA has removed it
from the carbaryl drinking water assessment. There were a small number
of detections of carbaryl reported to OPP as a result of a quality
control check of the Suffolk County database, ranging from 0.1 to 13
[mu]g/L. These values are more in line with other monitoring data for
carbaryl reported in the EPA assessment.
    Finally, both the commenter from the University of Florida and NRDC
are mistaken in their statements that that EPA's drinking water
assessment relied on default percent crop treated assumptions. In
particular, NRDC appears to have confused percent crop treated (PCT)
data for the percentage of a food commodity treated with carbaryl with
EPA's use of percent crop area (PCA) in the carbaryl drinking water
assessment. The default PCA (87%) represents the largest fraction of a
watershed that can be planted to any crop. This default PCA, which is
based on Geographic Information Systems (GIS) analysis of fairly large
watersheds\2\, is used in drinking water assessments to account for the
fact that not all land in a watershed is agricultural land (planted
with crops). Regional PCAs reflect the greatest fraction of a watershed
used in agriculture in each of the major drainage basins in the United
States. In either case, the drinking water assessment assumes that
carbaryl is applied to 100% of the agricultural land in the watershed,
regardless of the fraction of the watershed that is used in
agriculture.
---------------------------------------------------------------------------

    \2\ Large watershed having an 8 digit hydrologic unit code (HUC-
8).
---------------------------------------------------------------------------

    In sum, the revised dietary risk assessment for food shows that
acute dietary exposure and risk are below the Agency's level of concern
for the general U.S. population and all population subgroups. The
revised drinking water assessment also does not rely on the old
methodology, using DWLOCs. The drinking water assessment was not
limited to agriculture uses; EPA included the most recent available
monitoring data for carbaryl in urban and suburban areas in the revised
assessment. Last, estimated pesticide residues in drinking water were
incorporated directly into the exposure component of the dietary
assessment.
    3. CARES dietary exposure model--a. NRDC's claims. NRDC asserts
that EPA improperly relied upon Cumulative and Aggregate Risk
Evaluation System (CARES), a ``confidential'' industry model to assess
human health risks. While NRDC acknowledges that EPA may rely on a
proprietary model, it insists that EPA has not provided sufficient
detail about the model's ``built-in assumptions and calculation
methodologies.'' (Ref. 1 at 19).
    b. Public comments. Bayer asserts that during its development by
industry, with input from EPA and USDA, CARES was ``freely'' available
from CropLife

America by request. Bayer also notes that the model was reviewed at two
FIFRA SAP meetings in 2002 and 2004 (US EPA, SAP April 30 to May 1,
2002. CARES Model Review http://www.epa.gov/scipoly/sap; USEPA, SAP
April 29 to 30, 2004. A Model Comparison: Dietary and Aggregate
Exposure in Calendex, CARES and Lifeline. http://www.epa.gov/scipoly/
sap). On completion of the model, it was donated to The International
Life Sciences Institute (ILSI). CARES is now freely available from the
ILSI web site (http://www.ilsi.org).
    c. EPA's Response. In the 2003 IRED, EPA used the DEEM-
FCIDTM model to estimate dietary risks from carbaryl. The
carbaryl registrant submitted an assessment derived from CARES, which
EPA reviewed and compared with the Agency's results. However, the
Agency did not rely upon the CARES model in the Carbaryl IRED. EPA
relied upon the DEEM-FCIDTM model for both the 2003 human
health risk assessment supporting the IRED and the revised 2007 dietary
assessment supporting the carbaryl RED. Thus, any concerns regarding
the public availability of the CARES model are irrelevant to EPA's risk
assessment for the 2003 IRED.
    Nonetheless, it is worth noting that the CARES model has been
transferred to the ILSI Research Foundation and the CARES program and
source code is publicly available at no charge. In addition, in 2002,
the FIFRA SAP reviewed the underlying science, computational approaches
and ease of use of the CARES model. The FIFRA SAP's June 13, 2002
report (Ref. 22) provides results of the panel's deliberations. The
FIFRA SAP provided a series of recommendations designed to improve the
technical basis of the model and software system. In any case, CARES
meets OPP's criteria for use in regulatory decision making with respect
to public availability, transparency, and compliance with Agency policy
guidelines and NRDC's objection in this regard are without merit.
    4. Farmers' markets and roadside produce stands--a. NRDC's claims.
NRDC asserts that EPA did not explicitly consider food purchased at
farmer's markets, farm stands, ``U-PIK'' farms, or eaten from household
gardens (Ref. 1 at 19-20). NRDC suggests that, in the absence of data
to support EPA's belief that its exposure assessment adequately
accounts for food purchased at such locals, EPA include an uncertainty
factor to account for children who consume this source of food (Ref. 1
at 20).
    b. Public comments. Bayer noted that EPA adequately responded to
this issue in its October 26, 2004 Response to Comments on Phase 5 Risk
Assessment (Docket ID No. EPA-HQ-OPP-2003-0376-00008).
    c. EPA's response. In an Order responding to NRDC objections to
tolerances for different pesticides, EPA has addressed NRDC's claims
regarding pesticide exposure to persons who purchase food at roadside
stands or farmers' markets. (70 FR 733; 72 FR 662, December 5, 2007).
This is equally applicable to ``U-PIK'' farms and household gardens. As
EPA explained there, whether EPA relies on data from crop field trials
or monitoring data in estimating pesticide exposure, given the sampling
methods in field trials and food monitoring residue levels identified
from these sources are unlikely to understate residue levels at farm
stands. Moreover, EPA does not believe it is reasonable to assume that
farm stands sell food containing a significantly different residue
profile than found in PDP monitoring data. Therefore, this factor
introduces little to no uncertainty concerning the possibility of
underestimation of residues into EPA's analysis. In any case, EPA
hereby incorporates its prior response to these issues EPA relies on
its prior response to this issue and finds NRDC's contentions without
merit.
    5. Tolerances for cancelled uses--a. NRDC's claims. NRDC is
concerned that EPA proposed to increase tolerances for 20 commodities
and establish new tolerances for 7 commodities (Ref. 1 at 14-15).
Specifically, NRDC urges EPA not to make any tolerance reassessment
determination prior to completion of the carbamate cumulative risk
assessment. NRDC also insists that EPA revoke tolerances for all uses
of carbaryl that have been voluntarily cancelled. NRDC is particularly
concerned about imported food and products entering the United States
with carbaryl residues without triggering action by the FDA. NRDC is
also concerned about the effect that the failure to ``ban'' products
will have on the international community and in particular developing
countries. Specifically, NRDC asserts that manufacturers voluntarily
cancel the registration of high risk products to avoid Prior Informed
Consent (PIC) listings.
    b. Public comments. Bayer asserts in its comments that in the
carbaryl IRED EPA addressed NRDC's concern regarding the reassessment
of tolerances prior to the completion of the NMC cumulative risk
assessment. Bayer notes, however, that the IRED specifically provides
that the establishment of new tolerances or raising tolerances will be
deferred pending consideration of cumulative risk for the NMCs. The
IRED further provides that, for purposes of that document, the term
``reassessed'' does not imply that all of the tolerances for carbaryl
have been reassessed as required by FQPA, since these tolerances may
only be reassessed once the cumulative risk assessment of all carbamate
pesticides is considered. Rather, the IRED provided reassessed
tolerances for carbaryl in/on various commodities, supported by all of
the submitted residue data, only for the single carbamate chemical
carbaryl (Ref. 16 at 67).
    Bayer further expressed its belief that EPA's practice of revoking
tolerances after a sufficient period of time that allows existing
stocks bearing the use being cancelled to clear the channels of trade
is in compliance with the requirements of the FQPA. Finally, Bayer
argues that NRDC's concern about potential risk from new or increased
tolerances being established for carbaryl are not justified because the
tolerance reassessment process is not associated with labeling changes
that increase the maximum application rates or frequency of application
allowed by current labels. Bayer further notes that many of the
labeling amendments required by the IRED serve to reduce potential
human health and environmental risks. Bayer also notes that the
pursuant to the IRED most tolerances will be either reduced, revoked,
or left unchanged.
    c. EPA's response. Notwithstanding NRDC's insistence that EPA
revoke tolerances for uses that have been voluntarily canceled, NRDC
has not provided any basis for determining that tolerances for uses
that have been voluntarily cancelled do not meet the FFDCA standard
such that the tolerance must be revoked. Be that as it may, EPA has now
completed and released the cumulative risk assessment for the NMCs and,
therefore, all carbaryl tolerances are considered reassessed at this
time. With respect to tolerances associated with uses that have been
cancelled and/or deleted pursuant to section 6(f)(1) of FIFRA, EPA has
revoked the associated tolerances, except for the wheat tolerance,
which is still needed to cover imported wheat and any domestic wheat
that may receive inadvertent residues of carbaryl resulting from
carbaryl use to control grasshoppers and/or Mormon crickets on pasture
and rangeland. The Agency included carbaryl residues on wheat in the
cumulative risk assessment for the NMCs.
    The Agency has completed rulemaking proceedings to revoke and
modify the existing carbaryl tolerances,

and correct commodity definitions. EPA published a proposed tolerance
rule for carbaryl on May 21, 2008 (73 FR 29456) and a final tolerance
rule on September 10, 2008 (73 FR 52607). The final carbaryl tolerance
rule revokes tolerances associated with uses that have been cancelled
and/or deleted to date pursuant to section 6(f)(1) of FIFRA, allowing
sufficient time for existing stock to clear channels of trade, with the
exception of the tolerance for wheat. As a result of the final
tolerance rule, many existing carbaryl tolerances have been reassigned
to crop groups, and old commodity specific tolerances have been revoked
as new tolerances have been established for residues in/on various crop
groups and subgroups. New tolerances were also established for carbaryl
residues in/on the following raw agricultural commodities: aspirated
grain fractions, proso millet hay, sorghum stover, and sugar beet
roots. At the present time, sufficient data are available to determine
an appropriate tolerance for residues in/on aspirated grain fractions
(70 ppm), sugar beet roots (0.5 ppm), and sorghum stover (30.0 ppm).
Separate tolerances have been established for residues in the following
processed food/feed items: wet apple pomace (15.0 ppm), citrus fruit
oil (20.0 ppm), raisins (12.0 ppm), and rice hulls (30.0 ppm).
    Finally, to the extent that NRDC argues that tolerances must be
revoked simply because an active ingredient or use is not registered in
the United States, EPA disagrees. Nothing in the FFDCA requires that
tolerances be limited to pesticides that have a U.S. registration. In
fact, FIFRA explicitly recognizes that EPA may set import tolerances
under the FFDCA. See Section 33 of FIFRA (establishing fees and
decision review times for import tolerance applications). While EPA
often proposes to revoke tolerances after the cancellation of
associated uses because EPA believes the tolerances may no longer be
necessary, EPA has always recognized that a revocation can not proceed
on such grounds if foreign growers wish to rely on the tolerance. In
such circumstances, a tolerance can only be revoked if necessary data
to support the tolerance are not provided or if EPA determines that the
tolerance does not meet the safety standard.

B. Risk Characterization

    1. New data. In keeping with science policy developments for the
NMCs, EPA used data from a comparative cholinesterase study comparing
carbaryl-induced cholinesterase inhibition in adult and juvenile rats
to calculate a revised FQPA Safety Factor for carbaryl and to derive
the toxicology points of departure for risk assessment. Specifically,
this study was conducted to determine whether young animals are more
susceptible to the effects of carbaryl than adults. This oral study
showed that juvenile 11-day-old (PND11) pups were more sensitive to
inhibition of brain cholinesterase from carbaryl than adult rats.
    EPA conducted a benchmark dose analysis for the carbaryl
comparative cholinesterase study, using the same modeling methodology
used in the NMC cumulative risk assessment. A benchmark dose analysis
models the dose-response relationship with a dose-response curve, which
allows selection of doses corresponding to a specified level of
response, called a benchmark response. This analysis allows EPA to
determine a more appropriate point of departure from a toxicology study
rather than using the study NOAEL or LOAEL. (See Refs. 12, 23, and 24
for more information on benchmark dose modeling).
    The Agency estimated the 10% benchmark dose response
(BMD10) and the BMDL10, or lower 95% confidence
limit of the benchmark dose, for this study. The Agency also conducted
a full benchmark dose analysis of all rat oral toxicity studies for
adults; this analysis showed that the BMDL10 for pups is also
protective for adults. Because the brain is the target tissue for
carbaryl, and the brain BMDL10 of 1.1 milligrams/kilogram
(mg/kg) is also protective of cholinesterase inhibition in blood, then
the brain BMDL10 is the appropriate point of departure for
both children and adults in the revised carbaryl risk assessment. (See
Ref. 23 and Ref. 24 for additional details regarding the comparative
cholinesterase study).
    2. Revised FQPA safety factor. To complete the carbaryl IRED in
2003, EPA evaluated the potential for special sensitivity of infants
and children to carbaryl and the need for an additional FQPA Safety
Factor. After evaluating the entire toxicity database available for
carbaryl at that time, the FQPA Safety Factor, to account for special
susceptibility of infants and children, was reduced from 10X to 1X for
all scenarios, except for the chronic dietary endpoint where a 3X FQPA
SF was used to account for the lack of a NOAEL. This decision and
rationale is described in detail in the technical support documents for
the carbaryl IRED.
    As previously mentioned in Unit III.C.1. of this document, EPA has
revised the FQPA Safety Factor for carbaryl using the most recent data
on carbaryl age sensitivity. The new comparative cholinesterase study
data was used to derive a new FQPA Safety Factor by comparing the
BMD10 for brain cholinesterase inhibition between adults and
pups at postnatal day 11. Pups were 1.8x more sensitive to brain
cholinesterase inhibition than the adults; therefore, a 1.8X FQPA
Safety Factor was applied to both the NMC cumulative and the carbaryl-
specific risk assessments. This safety factor of 1.8X is applied to the
dermal endpoint because there are no comparative cholinesterase data in
offspring from dermal exposure, and because juvenile rats are 1.8X more
sensitive than adults based on the oral comparative cholinesterase
study in rats. The FQPA Safety Factor is 1X for oral and inhalation
endpoints because these endpoints are selected from the comparative
cholinesterase data for the most sensitive population (PND11 pups).
    3. Issues raised by NRDC concerning the FQPA safety factor--a.
NRDC's claims. NRDC objects to EPA's decision to reduce the FQPA Safety
Factor to 1X in the IRED and repeats earlier arguments that a
developmental neurotoxicity study (DNT) used by EPA in the 2004 IRED
does not provide a basis for removing the FQPA Safety Factor because
pups had effects at doses that did not produce effects in adults in the
DNT study. (Ref. 1 at 17, 18) In addition, NRDC maintains that EPA
should have applied an additional 3X uncertainty factor to account for
the failure to identify a No Observable Adverse Effect Level (NOAEL)
for brain morphometric changes in pups in the DNT study. Specifically,
NRDC argues that the low and mid-dose samples were ``damaged and
uninterpretable'' and thus this test did not produce a ``no observed
adverse effect level.'' (Ref. 1 at 17-19).
    b. Public comments. Bayer noted that EPA adequately responded to
this issue in its October 26, 2004 Response to Comments on Phase 5 Risk
Assessment (Docket ID No. 2003-0376-00008).
    c. EPA's response. Since the 2004 IRED, EPA has incorporated new
data into its assessment of carbaryl. In the process of completing the
carbaryl RED and the cumulative risk assessment for the NMCs, EPA re-
evaluated the toxicology database for carbaryl, which includes studies
submitted since the completion of the IRED. EPA received
pharmacokinetic data on the rapid reversibility of carbaryl effects
(Ref. 25), a comparative cholinesterase study to inform age-related
sensitivity to carbaryl (Ref. 23), and a dermal penetration study for
carbaryl (Ref. 26). As a result, the Agency revised the FQPA Safety
Factor in 2007 and selected new points

of departure using the new comparative cholinesterase data and
benchmark dose modeling.
    The comparative cholinesterase study was conducted specifically to
provide age-related sensitivity data for carbaryl to be used in the NMC
cumulative risk assessment. Experience with other NMCs has shown that
comparative cholinesterase studies provide a more accurate indication
of comparative adult and offspring sensitivity than the behavioral and
histopathological changes evaluated in the DNT study. The carbaryl
comparative cholinesterase study involved oral dosing of three age
groups of rats, adults (97 days old) and juveniles 11 or 17 days old
(postnatal day, PND, 11 or 17), followed by measurement of both brain
and blood cholinesterase. Based on a benchmark dose analysis of the
results of this study, EPA identified a clear point of departure (the
equivalent of a NOAEL) for brain cholinesterase effects in the young
and thus the sensitivity in the young is well-characterized. In these
circumstances, EPA finds that it has reliable data on pre- and post-
natal toxicity to remove (oral and inhalation) or reduce (dermal) the
10X FQPA Safety Factor.
    Based on the results of the benchmark dose analysis from the
comparative cholinesterase study, which provide the most sensitive data
available to date on age related sensitivity to carbaryl, juvenile
animals are 1.8X more sensitive to carbaryl induced cholinesterase
inhibition than adults. EPA has thus derived an FQPA Safety Factor of
1.8X. This safety factor of 1.8X is applied to the dermal endpoint
because there are no comparative cholinesterase data in offspring from
dermal exposure, and because juvenile rats are 1.8X more sensitive than
adults based on the oral comparative cholinesterase study in rats. The
FQPA Safety Factor is 1X for oral and inhalation endpoints because
these endpoints are selected from the comparative cholinesterase data
for the most sensitive population (PND11 pups).
    Moreover, NRDC's concern that EPA failed to apply an additional 3X
uncertainty factor to account for the failure to detect a NOAEL in the
DNT study is no longer relevant. Specifically, brain cholinesterase
inhibition in the PND 11 animals in the comparative cholinesterase
study was the most sensitive endpoint in this study; therefore, this
endpoint of 1.1 mg/kg/day was used as the point of departure for the
2007 carbaryl risk assessment. This new endpoint occurs at a lower dose
than NRDC's suggested extrapolated NOAEL (i.e., including a 3X
uncertainty factor) of 3.3 mg/kg/day for brain morphometry from the DNT
study. Because EPA's assessment is now based upon a lower endpoint,
NRDC's contention that EPA failed to apply an additional 3X uncertainty
factor to the point of departure derived from the DNT study is no
longer relevant.

C. Residential Exposure

    1. Aggregating exposures. The safety standard in FFDCA section 408
for tolerances requires that there be a reasonable certainty of no harm
from ``aggregate exposure to the pesticide chemical residue, including
all dietary exposures and all other exposure for which there is
reliable information.'' (21 U.S.C. 346a(b)(2)(A)(ii)). Further, in
evaluating the safety of tolerances EPA is directed to ``consider . . .
available information concerning the aggregate exposures of consumers .
. . to the pesticide chemical residue . . . including dietary exposure
under [all] tolerance[s] . . . in effect for the pesticide chemical
residue and exposure from other non-occupational sources.'' (21 U.S.C.
346a(b)(2)(D)(vi)).
    Unit VII.B. discusses EPA's assessment of aggregate dietary
exposure to carbaryl from residues in foods and water. That assessment
showed that the dietary exposure and risk are below the Agency's level
of concern for the general U.S. population and all population
subgroups; exposure to carbaryl residues in food comprises <100% of the
aPAD at the 99.9th percentile of exposure. Estimated dietary exposure
for the general U.S. population is 29% of the aPAD; exposure to
children age 1 to 2 years, the most highly exposed population subgroup,
comprises 60% of the aPAD. Although refined, these exposure estimates
still are likely to overstate exposure and risk.
    Pesticide residues to which humans are exposed from residential
uses of pesticides must be considered as part of section 408's
aggregate exposure calculus. The concern, of course, is that pesticide
tolerances should not be established or left in effect if dietary
exposures when combined with other sources of exposure exceed safe
levels.
    2. Residential exposure and risk assessment. Since the 2004 Amended
IRED, the Agency has revised the residential risk assessment for
carbaryl to incorporate the revised toxicology endpoints and FQPA
Safety Factor, the mitigation specified in the IRED (as well as the
mitigation specified in the RED for residential use of granular
formulations; namely, that granular formulations must be watered in
immediately), and confirmatory data received as a result of the generic
DCI for carbaryl. EPA received turf transferable residue (TTR) data for
granular formulations of carbaryl, as well as additional data to
support the use of carbaryl in pet collars. The granular TTR data were
incorporated into the revised risk assessment; however, the pet collar
data were considered but not incorporated because of data quality
issues. In addition, the Agency incorporated data from several studies
for pesticides applied to turf to estimate the percent of carbaryl
transferred from turf to a person's hand. (See Ref. 27 for details of
the revised carbaryl residential risk assessment).
    3. Pet collars--a. NRDC's claims. In its Petition, NRDC expressed
concern that EPA's assessment of pet collars significantly
underestimates exposure. (Ref. 1 at 4). NRDC therefore requested that
EPA provide information on the assumptions used to calculate flea
collar exposures. In particular, NRDC is concerned that EPA's
calculations do not take into account the possibility that pet sleep
with children, share intimate spaces or share hugs/kisses with
children. NRDC also contends that there are safer ``non-pesticide''
alternatives available.
    In addition, in a November 2007 petition to cancel all carbaryl pet
collar registrations, NRDC asserts that changes in this algorithm made
from the preliminary NMC cumulative assessment result in a repeated and
additive bias towards reducing the exposure estimate so that it
``appears'' that the pet collar uses do not exceed the Agency's level
of concern. (Ref. 2 at 5-7). Specifically, NRDC takes issue with the
following modifications made in the probabilistic assessment for
carbaryl as part of the NMC cumulative risk assessment:
     Assuming a child mouths only one hand at a time, thereby
dividing the hand-loading residues by 2X.
     Assuming the hand is fully replenished with residues from
a contaminated surface on an hourly basis rather than assuming (as done
previously with flea collar assessments) full replenishment between
each mouthing event, which NRDC contends is a more likely scenario for
children actively engaged with their pets.
     Assuming that the maximum time spent with a pet is 1.03
hrs./day. NRDC contends that EPA's assumption in previous assessments
of 2 hrs./day is a much more likely scenario for pre-schoolers who are
home all day with their pets and for school age children lying with
their pets watching TV.
     Assuming that only 1% of the surface area of a single hand
is mouthed, which is approximately 1/75

cm2 surface area. NRDC contends that EPA's assumption in
previous assessments of 20 cm2 is a more reasonable and
realistic estimate of the surface area likely to contact a child's
mouth repeatedly.
     Assuming that only 20 to 50% of the pesticide is removed
per mouthing event (saliva extraction factor). NRDC contends that EPA's
assumption in previous assessments that all of the pesticide is removed
is more reasonable and realistic.

NRDC also criticizes the Agency for not including inhalation as an
exposure route for residential post-application of flea collars. NRDC
also points out that inhalation was the only route of exposure that EPA
estimated in an earlier RED decision on another pesticide used in flea
collars.
    NRDC argues that all of these modifications in the Agency's
algorithm for calculating non-dietary hand-to-mouth exposures for
children bias towards reducing the exposure estimate. NRDC also
criticizes the Agency for stating that the modifications result from
the recommendations from the August 2005 FIFRA SAP. To the contrary,
NRDC contends that these modifications were never reviewed or
recommended by the FIFRA SAP. NRDC therefore asserts that EPA cannot
use this new method presented in the NMC cumulative assessment to
``reduce protections for children from pet uses of [carbamate]
pesticides''. (Ref. 2 at 7).
    b. Public comments. Bayer contends that NRDC is misinformed
regarding ``non-pesticide'' alternatives. In particular, Bayer takes
issue with NRDC's statement that ``[p]et products containing non-
pesticide growth regulators also can stop fleas from reproducing
successfully''. (Ref. 19 at 7, citing Ref. 1 at 4). Bayer points out
that by definition any product that controls pest growth is a pesticide
and that making pesticidal claims without registration is a violation
of federal law. Bayer further asserts that unspecified ``non-
pesticide'' alternatives have not been rigorously tested for efficacy
or safety. Thus, Bayer asserts that NRDC offers no real alternative to
the use of carbaryl-containing flea collars.
    c. EPA's response. NRDC is concerned that while EPA has determined
that pet collar uses are safe (with MOEs of greater than 1 million),
EPA's calculations significantly underestimate exposure\3\. NRDC
therefore requested that EPA provide information on the assumptions
used to calculate flea collar exposures. In particular, NRDC is
concerned that EPA's calculations do not take into account the
possibility that pets sleep with children, share intimate spaces or
share hugs/kisses with children.
---------------------------------------------------------------------------

    \3\ NRDC asserts that a MOE of 1 million relates to residential
postapplication exposures associated with pet collars. This is
incorrect. The MOE referred to relates to residential handler
(applicator) exposure as assessed in the 2003 carbaryl IRED.
---------------------------------------------------------------------------

    As a preliminary matter, it is important to note that EPA assessed
pet collars both in the individual chemical assessment and as part of
the NMC cumulative risk assessment. The single chemical assessment done
for carbaryl was a deterministic assessment. For the NMC cumulative
risk assessment, EPA performed a probabilistic assessment.
    With respect to the single chemical, deterministic assessment, the
assumptions used are based upon Agency standard values for estimating
exposure to pets as defined in the 1997 Draft SOPs for Residential
Exposure Assessments and amendments. (Refs. 6, 7, and 8). Specifically,
SOPs 9.2.1--Postapplication Dermal Dose from Pesticide Residues on Pets
and 9.2.2 - Postapplication Potential Dose Among Toddlers from
Incidental Nondietary Ingestion of Pesticide Residues on Pets from
Hand-to-Mouth Transfer describe the algorithms that provided the basis
for EPA's assessment. In addition, to the extent that EPA had chemical
specific data (e.g., transferable residue data) or made chemical
specific adjustments to the algorithms, they are explained in the
Revised Phase 5, Occupational and Residential Exposure Assessment and
Recommendations for the Reregistration Eligibility Decision Document
(RED), dated February 20, 2003.
    In sum, for the single chemical assessment, exposures to children
after contact with treated pets were addressed using the latest EPA
methodology, as described below:
     Only toddlers are considered because their exposures are
considered to be the most highly exposed population by the Agency;
     An equilibrium approach based on a single child ``hug'' of
the treated animal is used to assess dermal exposure (i.e., the skin
loads after a single contact with the treated animal and additional
contacts don't proportionally add exposures) as described in the
amendments to the residential SOPs (Ref. 6), the surface area of the
dermal hug is based on a toddler's skin surface area and typical
clothing;
     The Agency default for transferability of residues from
fur is 20%; however, a pet collar transferable residue study (MRID
45792201) was submitted and used in the assessment for comparative
purposes with the Agency's standard approach. The data from this study
were used to develop an alternative transferability factor of 2.6% for
dusts and liquid applications;
     The active lifetime of a collar is expected to be 120 days
based on label statements which were used by the Agency, a daily
emission term from the collar of 0.000290 mg/cm/gram ai/day2
is also based on measured data from Mississippi State University for a
pet collar. Additionally, data from a pet collar transferable residue
study (MRID 45792201) was submitted and used in the assessment for
comparative purposes with the Agency's standard approach the data from
this study were used to complete risk calculations using direct
measurements of transferable residue concentration on dogs;
     Risks are based on an even loading of residues across the
entire surface of a 30 lb dog which has been chosen as a representative
animal. The animal surface area was calculated using (12.3 * Body
Weight (g) 0.65) from the Agency's 1993 Wildlife Exposure Factors
Handbook (i.e., dog surface area of 5986 cm2);
     The approach used to address the hand-to-mouth exposure
pathway has been modified since the previous risk assessment. In the
previous assessment, contact with dogs was based on 40 events per day,
in each event, the palmar surface of the hands (i.e., 20
cm2/event) is placed in the mouth of the child contributing
to nondietary ingestion exposure. In the revised approach, the
frequency term has been modified to an equilibrium approach analogous
to the dermal exposure component (i.e., the frequency = 1) because the
transferable residue concentrations are from measured concentrations on
the hands following heavy rubbing/petting of a dog for 5 minutes. This
would result in significantly higher concentrations on the hands than
would be expected from a single contact.
    With respect to the single chemical assessment, NRDC asserts that
the Agency failed to properly take into account children hugging and
sleeping with pets. To the contrary, EPA's assessment is in fact based
upon toddler exposure through hugging and petting. Indeed, for maximum
exposure, EPA's assessment is based upon assumptions of hugging and
petting followed by mouthing activity. Thus, NRDC's concerns about
EPA's assessment not taking hugging into account are misplaced.
    The estimation of risk from dermal and oral exposures related to
pet collars is best described by means of combining both routes of
exposure. The Agency

combines risks resulting from total exposures to individual chemicals
when it is likely that they can occur simultaneously based on the use
pattern and the behavior associated with the exposure population. For
carbaryl, the Agency combined risk values (i.e., MOEs) for different
kinds of exposures associated with the pet collar scenario (dermal and
hand-to-mouth). These represent the standard set of exposures that are
typically added together when chemicals are used on pets because it is
logical that they can co-occur. It should be noted that the dermal and
hand-to-mouth assessments are considered conservative and that
combining the assessments is expected to provide a highly conservative
assessment of children's incidental oral exposure.
    EPA did not, however, separately assess exposure to toddlers while
sleeping with (near or next to) pets wearing a pet collar impregnated
with carbaryl. This is because EPA assumes that the ``hug'' or
equilibrium approach is adequately protective for all activities in
which a child engages that result in dermal exposure. EPA presented the
concept of a pet hug to assess dermal exposure to the FIFRA SAP on
September 21, 1999 (64 FR 48394, Ref. 28); this was considered to be a
reasonable approach. (Ref. 26). As described in the 1999 Overview
document presented to the SAP (Ref. 21), the residential pet SOP
``assumes a one to one transfer to the skin of surface area
representing both hands. This assumption suggests equilibrium is
established between the transferable residues on the pet and the
residues on the hand after contact. The concept of equilibrium ... has
utility in constructing scenarios such as a child hugging a dog or a
child sleeping with a dog. This is possible by assuming direct transfer
or transferable residue estimates to human surface area values.'' (Ref.
22 at 38 to 39).
    NRDC also criticizes the Agency for not including inhalation as an
exposure route for residential post-application of flea collars. In so
doing, NRDC points out that inhalation was the only route of exposure
that EPA estimated in an earlier RED decision on another pesticide used
in flea collars.
    EPA did not assess inhalation exposure to pet collars impregnated
with carbaryl because EPA generally assumes that residential post-
application inhalation exposures are negligible due to the low vapor
pressures associated with many pesticides. In the case of carbaryl,
this assumption is warranted. The vapor pressure of carbaryl is
sufficiently low (4.1 x 10-5 mmHg at 25 [deg]C) so that the
inhalation route of exposure will contribute insignificantly to the
overall estimated daily dose when compared to the combined exposures
resulting from the combination of the dermal and oral (i.e., hand-to-
mouth) routes. In other cases, this assumption might not be warranted.
For example, dichlorvos, another pesticide used in impregnated pet
collars, has a vapor pressure of 1.2 x 10-3 at 20 [deg]C,
which is considerably higher than that of carbaryl. The higher vapor
pressure suggests rapid volatilization at room temperature; therefore,
the Agency considered inhalation a potential route of exposure when
assessing residential exposure to dischlorvos from impregnated pet
collars. The Agency also considered dermal and hand-to-mouth routes of
exposure, in addition to inhalation. All potential routes of exposure
are considered for each pesticide on a case-by-case basis to determine
which routes will be the most significant contributors to exposure and
risk.
    In addition, as the basis for petitioning the Agency to cancel all
carbaryl pet collar registrations (submitted as part of NRDC's comments
on the NMC cumulative assessment), NRDC asserts that changes in this
algorithm made from the preliminary NMC cumulative assessment result in
a repeated and additive bias towards reducing the exposure estimate so
that it ``appears'' that the pet collar uses do not exceed the Agency's
level of concern. NRDC also criticizes the Agency for stating that the
modifications result from the recommendations from the August 2005
FIFRA SAP. To the contrary, NRDC contends that these modifications were
never reviewed or recommended by the FIFRA SAP. NRDC then asserts that
EPA cannot use this new method presented in the NMC cumulative
assessment to ``reduce protections for children from pet uses of
[carbamate] pesticides.'' (Ref. 2 at 7).
    EPA disagrees with NRDC's assertion that the techniques used in the
NMC cumulative assessment for pet collars results in an additive bias
towards reducing exposures and risks. The main difference between the
approach used to assess exposure to carbaryl from pet collars in the
2003 RED and the cumulative exposure assessment of the carbaryl pet
collar is that the cumulative exposure assessment uses probabilistic
techniques to estimate exposures and the single chemical assessment
uses deterministic techniques to assess exposures. Probabilistic
techniques have the advantage of using distributions of all available
data to describe the myriad of potential combinations of residues and
activity patterns that may occur as a child is interacting with a pet
wearing a carbaryl-impregnated collar. These potential combinations of
residues and activities provide a distribution of exposures for use in
risk assessment. Deterministic techniques rely on point estimates of
both residues and activity patterns. These point estimates may, for
example, represent averages or absolute maximum values for residues and
activity patterns.
    The specific modifications and the reasons for adopting the
modification are provided below:
     Assuming a child mouths only one hand at a time, thereby
dividing the hand-loading residues by 2X.
    This assumption is consistent with the way EPA has assessed hand-
to-mouth exposure in the past. Both the EPA Residential SOP methodology
(deterministic) and the revised hand-to-mouth algorithm used in the
Revised NMC cumulative risk assessment (probabilistic) are based upon
the assumption that a child can only place one hand in his/her mouth at
a time.
     Assuming the hand is fully replenished with residues from
a contaminated surface on an hourly basis rather than assuming (as done
previously with flea collar assessments) full replenishment between
each mouthing event, which NRDC contends is a more likely scenario for
kids actively engaged with their pets.
    As stated in the preliminary NMC cumulative risk assessment,
previous assumptions regarding replenishment were overly conservative
when used in a probabilistic model. These low MOEs were mainly due to
the incorporation of micro-activity data into EPA's macro activity
models (defined as human exposure models based on daily time step). The
non-dietary ingestion pathway was the least refined of the residential
exposure pathways modeled in the preliminary revised NMC cumulative
risk assessment. This input is part of the revised approach that was
developed in collaboration with ORD and is currently being used in the
Stochastic Human Exposure and Dose Simulation (SHEDS) model. (For a
full explanation of the implications of using microactivity data in a
macro activity model, see Ref. 29 p. 91.) The data used in the revised
assessment are based on a meta analysis provided by ORD. The meta
analysis relies upon the best available observational data on
children's mouthing frequency.
     Assuming that the maximum time spent with a pet is 1.03
hours/day. NRDC contends that EPA's assumption in previous assessments
of 2 hours/day is a much more likely scenario for pre-

schoolers who are home all day with their pets and for school age kids
lying with their pets watching TV.
    This assumption is based on data that involved videotaping
children's time spent with pets. (Ref. 30). As stated in the NMC
Cumulative Risk Assessment document, the duration of exposure is
assumed to be continuous contact rather than the intermittent contact
normally associated with pet care (e.g. walking, feeding). OPP is
attempting to draw the distinction between direct contact with a
treated pet and the time spent with a pet where there is limited
contact. For example, time spent with pets in and around the house may
not result in direct contact for the entire duration. The pet collar
scenario assessed in the revised NMC Risk Assessment uses pet fur
residues transferred to individuals at a rate found during a study of
shampooing and grooming for a duration of approximately 1 hour. Use of
these data to represent residential exposure to pets is likely to
encompass all other potential exposure scenarios involving direct or
indirect contact with treated pets.
     Assuming that only 1% of the surface area of a single hand
is mouthed, which is approximately 1/75 cm2 surface area.
NRDC contends that EPA's assumption in previous assessments of 20 cm2
is a more reasonable and realistic estimate of the surface area likely
to contact a child's mouth repeatedly.
    The Agency is unclear how NRDC determined that a surface area of 1%
was used in the NMC cumulative risk assessment. It should be noted that
the revised algorithm does not use a surface area (cm2), but
rather a distribution of fraction of the hand mouthed (unitless). The
distribution of fraction of surface area of hand mouthed ranged from a
mean of 0.129 to a maximum of 0.305. This is equivalent to
approximately 13 to 30.5 cm2, respectively (assuming a 100
cm2 total palmar surface area of the hand). In addition, as
a part of the algorithm used in SHEDS and CARES, the fraction of the
surface area of the hand mouthed is based on the best available data.
In some places in the revised NMC cumulative risk assessment, the
fraction of hand mouthed is referred to as surface area mouthed in
error.
     Assuming that only 20 to 50% of the pesticide is removed
per mouthing event (saliva extraction factor). NRDC contends that EPA's
assumption in previous assessments that all of the pesticide is removed
is more reasonable and realistic.
    The assumptions used in the hand-to-mouth assessment are based upon
data from several studies (Refs. 31, 32, and 33). The studies were
conducted to address the removal efficiency of residues from the hands
by saliva and other substances (e.g., ethanol) during mouthing events.
The resulting range, 20-50% removal efficiency, is the same used for
hand-to-mouth assessment in the Draft Residential SOPs and in the NMC
cumulative risk assessment; however, the Residential SOPs rely upon the
upper percentile of the range (50%) while the NMC cumulative risk
assessment made use of all available data to better estimate exposure
using a probabilistic approach.
    In sum, EPA made modifications in part because of the FIFRA SAP's
comments with respect to the limitations of the approach used in the
preliminary NMC cumulative risk assessment--most notable of which was
that the approach used in the preliminary NMC cumulative risk
assessment was likely to overestimate exposure and EPA should consider
not assessing this exposure pathway at all until it has better data.
EPA assessed this pathway (which the FIFRA SAP also suggested EPA) but
modified the algorithm in an effort to further refine the assessment.
    Furthermore, the FIFRA SAP provides independent scientific advice
to the EPA on health and safety related issues related to pesticides.
Thus, whether the FIFRA SAP reviewed and offered its recommendations on
the specifics of the modifications does not preclude EPA from making
such modifications (especially where the FIFRA SAP recommends that EPA
consider how the approach should be modified). Similarly, review by the
FIFRA SAP is not required in order for EPA to make a safety finding.
Accordingly, the issues raised by NRDC do not provide a basis for
revoking all carbaryl tolerances or cancelling pet collar
registrations.
    4. Farm children--a. NRDC's claims. Previously, NRDC had asserted
that farm children are especially vulnerable to pesticide exposure and
are not adequately considered. (Ref. 1. at 19). Notwithstanding EPA's
previous response to this issue, NRDC maintains that the Agency still
has not adequately addressed this issue.
    b. Public comments. Bayer noted that EPA adequately responded to
this issue in its October 26, 2004 Response to Comments on Phase 5 Risk
Assessment (Docket ID No. 2003-0376-00008).
    c. EPA's response. Simply asserting that the Agency has not (in
NRDC's opinion) adequately addressed an issue is not a basis upon which
to revoke a tolerance. In particular, NRDC has not provided any
additional information or data, nor has NRDC suggested in what respect
it finds the Agency's previous analysis and response to this issue is
inadequate. See Imidacloprid; Order Denying Objections to Issuance of
Tolerance, Final Order, 69 FR 30042 (May 26, 2004). EPA hereby
incorporates its prior response to this issue and finds NRDC's
contention without merit.

D. Conclusion

    NRDC's petitions to revoke all carbaryl tolerances are denied.
NRDC's arguments have not demonstrated that carbaryl tolerances are
unsafe; to the contrary, EPA continues to believe that its risk
assessments appropriately support its finding that the carbaryl
tolerances pose a reasonable certainty of no harm.

VIII. Regulatory Assessment Requirements

    As indicated previously, this action announces the Agency's order
denying a petition filed, in part, under section 408(d) of FFDCA. As
such, this action is an adjudication and not a rule. The regulatory
assessment requirements imposed on rulemaking do not, therefore, apply
to this action.

IX. Submission to Congress and the Comptroller General