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Imidacloprid - Pesticide Tolerances for Emergency Exemptions 2/97

40 CFR Part 180
[OPP-300460; FRL-5594-2]
RIN 2070-AB78
Imidacloprid; Pesticide Tolerances for Emergency Exemptions
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.

SUMMARY: This regulation establishes a time-limited tolerance for combined
residues of the pesticide imidacloprid in or on the raw agricultural commodity
crop group, cucurbits (Crop Group 9 cucumbers, melons, and squash) in
connection with EPA's granting of emergency exemptions under section 18 of the
Federal Insecticide, Fungicide, and Rodenticide Act authorizing use of
imidacloprid on cucurbits in Texas and California. This regulation establishes
maximum permissible levels for residues of imidacloprid in these foods. This
tolerance will expire on March 31, 1998.

DATES: This regulation becomes effective March 19, 1997. The entry in the
table expires on March 31, 1998. Objections and requests for hearings must be
received by EPA on or before May 19, 1997.

ADDRESSES: Written objections and hearing requests, identified by the docket
control number, [OPP-300460], must be submitted to: Hearing Clerk (1900),
Environmental Protection Agency, Rm. M3708, 401 M St., SW., Washington, DC
20460. Fees accompanying objections and hearing requests shall be labeled
"Tolerance Petition Fees" and forwarded to: EPA Headquarters Accounting
Operations Branch, OPP (Tolerance Fees), P.O. Box 360277M, Pittsburgh, PA
15251. A copy of any objections and hearing requests filed with the Hearing
Clerk identified by the docket control number, [OPP-300460], must also be
submitted to: Public Response and Program Resources Branch, Field Operations
Division (7506C), Office of Pesticide Programs, Environmental Protection
Agency, 401 M St., SW., Washington, DC 20460. In person, bring a copy of
objections and hearing requests to Rm. 1132, CM #2, 1921 Jefferson Davis
Highway., Arlington, VA.

A copy of objections and hearing requests filed with the Hearing Clerk may
also be submitted electronically by sending electronic mail (e-mail) to: opp- Such copies
of objections and hearing requests must be
submitted as an ASCII file avoiding the use of special characters and any form
of encryption. Copies of objections and hearing requests will also be accepted
on disks in WordPerfect 5.1 file format or ASCII file format. All copies of
objections and hearing requests in electronic form must be identified by the
docket control number [OPP-300460]. No Confidential Business Information (CBI)
should be submitted through e-mail. Electronic copies of objections and
hearing requests on this rule may be filed online at many Federal Depository

FOR FURTHER INFORMATION CONTACT: By mail: Andrea Beard, Registration Division
(7505W), Office of Pesticide Programs, Environmental Protection Agency, 401 M
St., SW., Washington, DC 20460. Office location, telephone number, and e-mail:
Sixth Floor, Crystal Station #1, 2800 Jefferson Davis Highway, Arlington, VA
22202. (703) 308-8791, e-mail:

SUPPLEMENTARY INFORMATION: EPA, pursuant to section 408(e) and (l)(6) of the
Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a(e) and (l)(6), is
establishing tolerances for residues of the pesticide imidacloprid (1-[(6-
chloro-3-pyridinyl)methyl]-N-nitro-2- imidazolidinimine), in or on cucurbits,
at 0.2 part per million (ppm). This tolerance will expire and be revoked
automatically without further action by EPA on March 31, 1998.

I. Background and Statutory Authority

The Food Quality Protection Act of 1996 (FQPA) (Pub. L. 104-170) was signed
into law August 3, 1996. FQPA amends both the Federal Food, Drug, and Cosmetic
Act (FFDCA), 21 U.S.C. 301 et seq., and the FIFRA, 7 U.S.C. 136 et seq. The
FQPA amendments went into effect immediately. Among other things, FQPA amends
FFDCA to bring all EPA pesticide tolerance-setting activities under a new
section 408 with a new safety standard and new procedures. These activities
are described below and discussed in greater detail in the final rule
establishing the time- limited tolerance associated with the emergency
exemption for use of propiconazole on sorghum (61 CFR 58135, November 13,

New section 408(b)(2)(A)(i) allows EPA to establish a tolerance (the legal
limit for a pesticide chemical residue in or on a food) only if EPA determines
that the tolerance is "safe." Section 408(b)(2)(A)(ii) defines "safe" to
mean that "there is a reasonable certainty that no harm will result from
aggregate exposure to the pesticide chemical residue, including all
anticipated dietary exposures and all other exposures for which there is
reliable information." This includes exposure through drinking water, but
does not include occupational exposure. Section 408(b)(2)(C) requires EPA to
give special consideration to exposure of infants and children to the
pesticide chemical residue in establishing a tolerance and to "ensure that
there is a reasonable certainty that no harm will result to infants and
children from aggregate exposure to the pesticide chemical residue...."

Section 18 of FIFRA authorizes EPA to exempt any Federal or State agency from
any provision of FIFRA, if EPA determines that "emergency conditions exist
which require such exemption." This provision was not amended by FQPA. EPA
has established regulations governing such emergency exemptions in 40 CFR part

Section 408(l)(6) requires EPA to establish a time-limited tolerance or
exemption from the requirement for a tolerance for pesticide chemical residues
in food that will result from the use of a pesticide under an emergency
exemption granted by EPA under section 18 of FIFRA. Section 408(l)(6) also
requires EPA to promulgate regulations by August 3, 1997, governing the
establishment of tolerances and exemptions under section 408(l)(6) and
requires that the regulations be consistent with section 408(b)(2) and (c)(2)
and FIFRA section 18.

Section 408(l)(6) allows EPA to establish tolerances or exemptions from the
requirement for a tolerance, in connection with EPA's granting of FIFRA
section 18 emergency exemptions, without providing notice or a period for
public comment. Thus, consistent with the need to act expeditiously on
requests for emergency exemptions under FIFRA, EPA can establish such
tolerances or exemptions under the authority of section 408(e) and (l)(6)
without notice and comment rulemaking.

In establishing section 18-related tolerances and exemptions during this
interim period before EPA issues the section 408(l)(6) procedural regulation
and before EPA makes its broad policy decisions concerning the interpretation
and implementation of the new section 408, EPA does not intend to set
precedents for the application of section 408 and the new safety standard to
other tolerances and exemptions. Rather, these early section 18 tolerance and
exemption decisions will be made on a case-by-case basis and will not bind EPA
as it proceeds with further rulemaking and policy development. EPA intends to
act on section 18- related tolerances and exemptions that clearly qualify
under the new law.

II. Emergency Exemption for Imidacloprid on Cucurbits and FFDCA Tolerances

The Texas Department of Agriculture and the California Department of Pesticide
Regulation availed themselves of the authority to declare the existence of a
crisis situation within their states, on January 27, and February 5, 1997,
respectively, thereby authorizing use under FIFRA section 18 of imidacloprid
on cucurbits to control white flies. The States of Texas and California have
also requested specific exemptions for this use of imidacloprid. Texas and
California stated that an emergency situation was present due to this recently
introduced pest, its devastating effects on the cucurbit crop, and its
resistance to registered alternatives. Texas and California state that this
pest can have devastating effects on growers' production and revenue. After
having reviewed their submission, EPA concurs that an emergency condition

As part of its assessment of these crisis declarations, EPA assessed the
potential risks presented by residues of imidacloprid in or on cucurbits. In
doing so, EPA considered the new safety standard in FFDCA section 408(b)(2),
and EPA decided to grant the section 18 exemptions only after concluding that
the necessary tolerance under FFDCA section 408(l)(6) would clearly be
consistent with the new safety standard and with FIFRA section 18. This
tolerance for imidacloprid will permit the marketing of cucurbits treated in
accordance with the provisions of the section 18 emergency exemptions.
Consistent with the need to move quickly on the emergency exemptions and to
ensure that the resulting food is safe and lawful, EPA is issuing this
tolerance without notice and opportunity for public comment under section
408(e) as provided for in section 408(l)(6). Although this tolerance will
expire and be revoked automatically without further action by EPA on March 31,
1998, under FFDCA section 408(l)(5), residues of imidacloprid not in excess of
the amount specified in the tolerance remaining in or on cucurbits after that
date will not be unlawful, provided the pesticide is applied during the term
of, and in accordance with all the conditions of, the emergency exemptions.
EPA will take action to revoke this tolerance earlier if any experience with,
scientific data on, or other relevant information on this pesticide indicate
that the residues are not safe.

EPA has not made any decisions about whether imidacloprid meets the
requirements for registration under FIFRA section 3 for use on cucurbits, or
whether a permanent tolerance for imidacloprid for cucurbits would be
appropriate. This action by EPA does not serve as a basis for registration of
imidacloprid by a State for special local needs under FIFRA section 24(c). Nor
does this action serve as the basis for any State other than Texas and
California to use this product on this crop under section 18 of FIFRA without
following all provisions of section 18 as identified in 40 CFR part 166. For
additional information regarding the emergency exemptions for imidacloprid,
contact the Agency's Registration Division at the address provided above.

III. Risk Assessment and Statutory Findings

EPA performs a number of analyses to determine the risks from aggregate
exposure to pesticide residues. First, EPA determines the toxicity of
pesticides based primarily on toxicological studies using laboratory animals.
These studies address many adverse health effects, including (but not limited
to) reproductive effects, developmental toxicity, toxicity to the nervous
system, and carcinogenicity. For many of these studies, a dose-response
relationship can be determined, which provides a dose that causes adverse
effects (threshold effects) and doses causing no observed effects (the "no-
observed effect level" or "NOEL").

Once a study has been evaluated and the observed effects have been determined
to be threshold effects, EPA generally divides the NOEL from the study with
the lowest NOEL by an uncertainty factor (usually 100 or more) to determine
the Reference Dose (RfD). The RfD is a level at or below which daily aggregate
exposure over a lifetime will not pose appreciable risks to human health. An
uncertainty factor (sometimes called a "safety factor") of 100 is commonly
used since it is assumed that people may be up to 10 times more sensitive to
pesticides than the test animals, and that one person or subgroup of the
population (such as infants and children) could be up to 10 times more
sensitive to a pesticide than another. In addition, EPA assesses the potential
risks to infants and children based on the weight of the evidence of the
toxicology studies and determines whether an additional uncertainty factor is
warranted. Thus, an aggregate daily exposure to a pesticide residue at or
below the RfD (expressed as 100 percent or less of the RfD) is generally
considered by EPA to pose a reasonable certainty of no harm.

Lifetime feeding studies in two species of laboratory animals are conducted to
screen pesticides for cancer effects. When evidence of increased cancer is
noted in these studies, the Agency conducts a weight-of-the-evidence review of
all relevant toxicological data including short-term and mutagenicity studies
and structure-activity relationships. Once a pesticide has been classified as
a potential human carcinogen, different types of risk assessments (e.g.,
linear low-dose extrapolations or margin of exposure calculation based on the
appropriate NOEL) will be carried out based on the nature of the carcinogenic
response and the Agency's knowledge of its mode of action.

In examining aggregate exposure, FFDCA section 408 requires that EPA take into
account available and reliable information concerning exposure from the
pesticide residue in the food in question, residues in other foods for which
there are tolerances, and other non- occupational exposures, such as where
residues leach into groundwater or surface water that is consumed as drinking
water. Dietary exposure to residues of a pesticide in a food commodity are
estimated by multiplying the average daily consumption of the food forms of
that commodity by the tolerance level or the anticipated pesticide residue
level. The Theoretical Maximum Residue Contribution (TMRC) is an estimate of
the level of residues consumed daily if each food item contained pesticide
residues equal to the tolerance. The TMRC is a "worst case" estimate since
it is based on the assumptions that food contains pesticide residues at the
tolerance level and that 100 percent of the crop is treated by pesticides that
have established tolerances. If the TMRC exceeds the RfD or poses a lifetime
cancer risk that is greater than approximately one in a million, EPA attempts
to derive a more accurate exposure estimate for the pesticide by evaluating
additional types of information (anticipated residue data and/or percent of
crop treated data) which show, generally, that pesticide residues in most
foods when they are eaten are well below established tolerances.

IV. Aggregate Risk Assessments, Cumulative Risk Discussion, and Determination
of Safety

Consistent with section 408(b)(2)(D), EPA has reviewed the available
scientific data and other relevant information in support of this action.
Imidacloprid is registered by EPA for use on turf, as a termiticide, and for
flea control on pets. At this time EPA is not in possession of a registration
application for imidacloprid on cucurbits. However, based on information
submitted to the Agency, EPA has sufficient data to assess the hazards of
imidacloprid and to make a determination on aggregate exposure, consistent
with section 408(b)(2), for the time-limited tolerance for residues of
imidacloprid on cucurbits at 0.2 ppm. EPA's assessment of the dietary
exposures and risks associated with establishing this tolerance follows.

A. Toxicological Profile

1. Chronic toxicity. Based on the available chronic toxicity data, the EPA's
Office of Pesticide Programs (OPP) has established the RfD for imidacloprid at
0.057 milligrams/kilogram/day (mg/kg/day). The RfD for imidacloprid is based
on a 2-year feeding study in rats with a NOEL of 5.7 mg/kg/day and an
uncertainty factor of 100. An increase in thyroid lesions in males was
observed at the Lowest Effect Level (LEL) at 16.9 mg/kg/day.

2. Acute toxicity. Based on the available acute toxicity data, OPP has
determined that the NOEL of 24 mg/kg/day from the developmental toxicity study
in rabbits should be used to assess risk from acute toxicity. Maternal effects
observed at the LEL of 72 mg/kg/day included decreased body weight and
increased resorptions and abortions. Fetal effects observed at the LEL of 72
mg/kg/day included an increase in skeletal abnormalities. The population
subgroup of concern for this risk assessment is females 13+ years and older.
This subgroup takes into account both maternal and fetal effects.

3. Short- and intermediate-term toxicity. OPP has determined that available
data do not demonstrate that imidacloprid has dermal or inhalation toxicity
potential. Therefore, short-term or intermediate- term dermal and inhalation
risk assessments, for occupational and residential exposure scenarios, are not

4. Carcinogenicity. Using its Guidelines for Carcinogen Risk Assessment
published September 24, 1986 (51 FR 33992), EPA has classified imidacloprid as
a "Group E" chemical (no evidence of carcinogenicity for humans) based on
the results of carcinogenicity studies in two species. The doses tested are
adequate for identifying a cancer risk. Thus, a cancer risk assessment would
not be appropriate.

B. Aggregate Exposure

Tolerances have been established (40 CFR 180.472) for the combined residues of
imidacloprid (1-[(6-chloro-3-pyridinyl)methyl]-N-nitro-2- imidazolidinimine)
and its metabolites containing 6-chloropyridinyl moiety expressed in or on
certain raw agricultural commodities ranging from 0.02 ppm in eggs to 3.5 ppm
in Brassica vegetable crop group (cabbage, chinese cabbage, and Kale) and head
and leaf lettuce. There are no livestock feed items associated with these
section 18 requests, so no additional livestock dietary burden will result
from this section 18 registration. Therefore, existing meat/milk/poultry
tolerances are adequate.

In conducting this exposure assessment, EPA has made very conservative
assumptions -- 100% of cucurbits and all other commodities having imidacloprid
tolerances will contain imidacloprid tolerance residues and those residues
would be at the level of the tolerance -- which result in an overestimate of
human dietary exposure. Thus, in making a safety determination for this
tolerance, EPA is taking into account this conservative exposure assessment.

1. Chronic exposure. Given the emergency nature of this request for the use of
imidacloprid and the resulting need for a timely analysis and risk assessment,
EPA has utilized the TMRC to estimate chronic dietary exposure from the
tolerances for imidacloprid on cucurbits at 0.2 ppm. The TMRC is obtained by
multiplying the tolerance level residue for cucurbits by the average
consumption data, which estimate the amount of cucurbits eaten by various
population subgroups. This calculation is performed as well for every food
having existing imidacloprid tolerances. The risk assessment is therefore
considered to be overestimated. The Agency has extensive experience refining
chronic dietary risk assessments for a broad range of pesticide chemicals. It
is OPP's experience that when the chronic dietary risk assessment is refined
using anticipated residue contribution (ARC) estimates derived from
anticipated residue levels and percent crop treated data, the percent of the
RfD occupied by the ARC is generally in the range of an order of magnitude
lower than the percent of the RfD occupied by the unrefined TMRC. A similar
decrease in estimated exposure to imidacloprid is expected once more refined
data is received based on ARCs for imidacloprid on some crops.

In examining aggregate exposure, FQPA directs EPA to consider available
information concerning exposures from the pesticide residue in food and all
other non-occupational exposures. The primary non-food sources of exposure the
Agency looks at include drinking water (whether from groundwater or surface
water), and exposure through pesticide use in gardens, lawns, or buildings
(residential and other indoor uses).

Based on the available studies used in EPA's assessment of environmental risk,
imidacloprid is persistent and could potentially leach into groundwater, and
run off to surface water under certain environmental conditions. There is no
established Maximum Concentration Level (MCL) for residues of imidacloprid in
drinking water. No drinking water health advisories have been issued for
imidacloprid. The "Pesticides in Groundwater Database" (EPA 734-12-92-001,
September 1992) has no information concerning imidacloprid.

Because the Agency lacks sufficient water-related exposure data to complete a
comprehensive drinking water risk assessment for many pesticides, EPA has
commenced and nearly completed a process to identify a reasonable yet
conservative bounding figure for the potential contribution of water-related
exposure to the aggregate risk posed by a pesticide. In developing the
bounding figure, EPA estimated residue levels in water for a number of
specific pesticides using various data sources. The Agency then applied the
estimated residue levels, in conjunction with appropriate toxicological
endpoints (RfD's or acute dietary NOEL's) and assumptions about body weight
and consumption, to calculate, for each pesticide, the increment of aggregate
risk contributed by consumption of contaminated water. While EPA has not yet
pinpointed the appropriate bounding figure for consumption of contaminated
water, the ranges the Agency is continuing to examine are all below the level
that would cause imidacloprid to exceed the RfD if the tolerance being
considered in this document were granted. The Agency has therefore concluded
that the potential exposures associated with imidacloprid in water, even at
the higher levels the Agency is considering as a conservative upper bound,
would not prevent the Agency from determining that there is a reasonable
certainty of no harm if the tolerance is granted.

2. Acute exposure. EPA has not estimated non-occupational exposures other than
dietary for imidacloprid. Acceptable, reliable data are not currently
available with which to assess acute risk. Imidacloprid is registered for turf
pest control. While dietary and residential scenarios could possibly occur in
a single day, imidacloprid would rarely be present on both the food eaten and
the lawn on that single day. Even assuming this were the case, it is yet more
unlikely that residues would be present at tolerance level on all food eaten
that day for which imidacloprid tolerances exist, as is assumed in the acute
dietary risk analysis, and on the lawn that same day. Because the acute
dietary exposure estimate assumes tolerance level residues and 100% crop
treated for all crops evaluated, it is a large over-estimate of exposure and
it is considered to be protective of any acute exposure scenario.

C. Cumulative Exposure to Substances with Common Mechanism of Toxicity

Section 408(b)(2)(D)(v) requires that, when considering whether to establish,
modify, or revoke a tolerance, the Agency consider "available information"
concerning the cumulative effects of a particular pesticide's residues and
"other substances that have a common mechanism of toxicity." The Agency
believes that "available information" in this context might include not only
toxicity, chemistry, and exposure data, but also scientific policies and
methodologies for understanding common mechanisms of toxicity and conducting
cumulative risk assessments. For most pesticides, although the Agency has some
information in its files that may turn out to be helpful in eventually
determining whether a pesticide shares a common mechanism of toxicity with any
other substances, EPA does not at this time have the methodologies to resolve
the complex scientific issues concerning common mechanism of toxicity in a
meaningful way. EPA has begun a pilot process to study this issue further
through the examination of particular classes of pesticides. The Agency hopes
that the results of this pilot process will increase the Agency's scientific
understanding of this question such that EPA will be able to develop and apply
scientific principles for better determining which chemicals have a common
mechanism of toxicity and evaluating the cumulative effects of such chemicals.
The Agency anticipates, however, that even as its understanding of the science
of common mechanisms increases, decisions on specific classes of chemicals
will be heavily dependent on chemical-specific data, much of which may not be
presently available.

Although at present the Agency does not know how to apply the information in
its files concerning common mechanism issues to most risk assessments, there
are pesticides as to which the common mechanism issues can be resolved. These
pesticides include pesticides that are toxicologically dissimilar to existing
chemical substances (in which case the Agency can conclude that it is unlikely
that a pesticide shares a common mechanism of activity with other substances)
and pesticides that produce a common toxic metabolite (in which case common
mechanism of activity will be assumed).

EPA does not have, at this time, available data to determine whether
imidacloprid has a common mechanism of toxicity with other substances or how
to include this pesticide in a cumulative risk assessment. Unlike other
pesticides for which EPA has followed a cumulative risk approach based on a
common mechanism of toxicity, imidacloprid does not appear to produce a toxic
metabolite produced by other substances. For the purposes of this tolerance
action, therefore, EPA has not assumed that imidacloprid has a common
mechanism of toxicity with other substances.

D. Determination of Safety for U.S. Population

1. Chronic risk. Using the conservative exposure assumptions described above,
and taking into account the completeness and reliability of the toxicity data,
EPA has concluded that aggregate dietary exposure to imidacloprid will utilize
16% of the RfD for the U.S. population. EPA generally has no concern for
exposures below 100 percent of the RfD because the RfD represents the level at
or below which daily aggregate dietary exposure over a lifetime will not pose
appreciable risks to human health. Despite the potential for exposure to
imidacloprid in drinking water, EPA does not expect the aggregate exposure to
exceed 100% of the RfD. EPA concludes that there is a reasonable certainty
that no harm will result from aggregate exposure to imidacloprid residues.

2. Acute risk. For the population subgroup of concern, females 13+ and older
(accounts for both maternal and fetal exposure), the calculated Margin of
Exposure (MOE) value is 480. This MOE does not exceed the Agency's level of
concern for acute dietary exposure.

E. Determination of Safety for Infants and Children

In assessing the potential for additional sensitivity of infants and children
to residues of imidacloprid, EPA considered data from developmental toxicity
studies in the rat and rabbit and a 2-generation reproduction study in the
rat. The developmental toxicity studies are designed to evaluate adverse
effects on the developing organism resulting from pesticide exposure during
prenatal development to one or both parents. Reproduction studies provide
information relating to effects from exposure to the pesticide on the
reproductive capability of mating animals and data on systemic toxicity.

In the rat developmental study, the maternal (systemic) NOEL was 30 mg/kg/day,
based on decreased weight gain at the LOEL of 100 mg/kg/day. The developmental
(fetal) NOEL was 30 mg/kg/day based on increased wavy ribs at the LOEL of 100
mg/kg/day. In the rabbit developmental study, the maternal (systemic) NOEL was
24 mg/kg/day, based on decreased body weight, increased resorptions and
abortions, and death at the LOEL of 72 mg/kg/day. The developmental (fetal)
NOEL was 24 mg/kg/day, based on decreased body weight and increased skeletal

anomalies at the LOEL of 72 mg/kg/day.

In the rat developmental study, the developmental (fetus) and maternal
(mother) NOELs occur at the same dose level, 24 mg/kg/day. The same response
is seen in the rabbit developmental study with the developmental (fetus) and
maternal (mother) NOELs occurring at the same dose level of 30 mg/kg/day. This
suggests that there are no special prenatal sensitivities for unborn children
in the absence of maternal toxicity. However, a detailed analysis of the
developmental studies indicates that the skeletal findings (wavy ribs and
other anomalies) in both the rat and rabbit fetuses are severe malformations
which occurred in the presence of slight toxicity (decreases of body weight)
in the maternal animals. Additionally, in rabbits, there were resorptions and
abortions which can be attributed to acute maternal exposure. This information
has been interpreted by the Toxicology Endpoint Selection Committee (TESC) as
indicating a potential acute dietary risk for pre- natally exposed infants.

In the rat reproduction study, the maternal (systemic) NOEL was 55 mg/kg/day
(the highest dose tested). The reproductive/developmental NOEL (effect on the
pup) was 8 mg/kg/day, based on decreased pup body weight during lactation in
both generations at the LOEL of 19 mg/kg/ day.

In the 2-generation rat reproduction study, the maternal NOEL is 55 mg/kg/day
and the NOEL for decreased pup body weight during lactation is 8 mg/kg/day
with the LOEL at 19 mg/kg/day. This study shows that adverse postnatal
development of pups occurs at levels (19 mg/kg/day) which are lower than the
NOEL for the parental animals (55 mg/kg/day). Therefore, the pups are more
sensitive to the effects of imidacloprid than parental animals. The pup NOEL
of 8 mg/kg/day in the reproduction study is 1.4 times greater than the NOEL of
5.7 from the 2-year rat feeding study which was the basis of the RfD. The TMRC
value for the most highly exposed infants and children subgroup (children 1 to
6 years old) occupies 31.0% of the RfD.

1. Chronic risk. Using the conservative exposure assumptions described above,
EPA has concluded that the percent of the RfD that will be utilized by
aggregate exposure to residues of imidacloprid ranges from 12 percent for
nursing infants, up to 32 percent for children 1 to 6 years old. Therefore,
taking into account the completeness and reliability of the toxicity data and
the conservative exposure assessment, EPA concludes that there is a reasonable
certainty that no harm will result to infants and children from aggregate
exposure to imidacloprid residues.

2. Acute risk. At present, the acute dietary MOE for females 13+ years old
(accounts for both maternal and fetal exposure) is 480. This MOE calculation
was based on the developmental NOEL in rabbits of 24 mg/kg/day. Maternal
effects observed at the LEL of 72 mg/kg/day included decreased body weight and
increased resorptions and abortions. Fetal effects observed at the LEL of 72
mg/kg/day included an increase in skeletal abnormalities. This risk assessment
also assumed 100% crop treated with tolerance level residues on all treated
crops consumed, resulting in a significant over-estimate of dietary exposure.
The large acute dietary MOE calculated for females 13+ years old provides
assurance that there is a reasonable certainty of no harm for both females 13+
years and the pre-natal development of infants.

FFDCA section 408 provides that EPA shall apply an additional tenfold margin
of exposure (safety) for infants and children in the case of threshold effects
to account for pre-and post-natal toxicity and the completeness of the
database unless EPA determines that a different MOE (safety) will be safe for
infants and children. Margins of exposure (safety) are often referred to as
uncertainty (safety) factors. EPA believes that reliable data support using
the standard MOE (usually 100X for combined inter- and intra-species
variability) and not the additional tenfold MOE when EPA has a complete data
base under existing guidelines and when the severity of the effect in infants
or children or the potency or unusual toxic properties of a compound do not
raise concerns regarding the adequacy of the standard MOE. Based on current
toxicological data requirements, the database for imidacloprid relative to
pre- (provided by rat and rabbit developmental studies) and post-natal
(provided by the rat reproduction study) toxicity is complete. Further, as
noted above, the acute dietary MOE for women 13+ years or older is 480. This
large MOE demonstrates that the prenatal exposure to infants is not a
toxicological concern at this time, and the additional uncertainty factor is
not needed to protect the safety of infants and children.

Both chronic and acute dietary exposure risk assessments assume 100% crop
treated and use tolerance level residues for all commodities. Refinement of
these dietary risk assessments by using percent crop treated and anticipated
residue data would greatly reduce dietary exposure. Therefore, both of these
risk assessments are also an over- estimate of dietary risk. Consideration of
anticipated residues and percent crop treated would likely result in an
anticipated residue contribution (ARC) which would occupy a percent of the RfD
that is likely to be significantly lower than the currently calculated TMRC
value. Additionally, the acute dietary MOE would be greater than the current
MOE. This provides an adequate safety factor for children during the prenatal
and postnatal development.

It is unlikely that the dietary risk will exceed 100 percent of the RfD or
that the acute MOE would be greater than the currently calculated value if, in
the future, an additional safety factor is deemed appropriate, when considered
in conjunction with a refined exposure estimate. Therefore, EPA concludes that
there is reasonable certainty that no harm will result to infants and children
from aggregate exposure to imidacloprid residues.

V. Other Considerations

The metabolism of imidacloprid in plants and animals is adequately understood
for the purposes of these tolerances. There are no Mexican, Canadian, or Codex
maximum residue levels established for residues of imidacloprid on cucurbits.
There is a practical analytical method for detecting and measuring levels of
imidacloprid in or on food with a limit of detection that allows monitoring of
food with residues at or above the levels set in these tolerances. EPA has
provided information on this method to FDA. The method is available to anyone
who is interested in pesticide residue enforcement from: By mail, Calvin
Furlow, Public Response and Program Resources Branch, Field Operations
Division (7506C), Office of Pesticide Programs, Environmental Protection
Agency, 401 M St. SW., Washington, DC 20460. Office location and telephone
number: Crystal Mall #2, Rm 1128, 1921 Jefferson Davis Hwy., Arlington, VA

22202, 703-305-5805.

VI. Conclusion

Therefore, a tolerance in connection with the FIFRA section 18 emergency
exemptions is established for residues of imidacloprid in/on cucurbits at 0.2
ppm. This tolerance will expire on March 31, 1998.

VII. Objections and Hearing Requests

The new FFDCA section 408(g) provides essentially the same process for persons
to "object" to a tolerance regulation issued by EPA under new section 408(e)
and (l)(6) as was provided in the old section 408 and in section 409. However,
the period for filing objections is 60 days, rather than 30 days. EPA
currently has procedural regulations which govern the submission of objections
and hearing requests. These regulations will require some modification to
reflect the new law. However, until those modifications can be made, EPA will
continue to use those procedural regulations with appropriate adjustments to
reflect the new law.

Any person may, by May 19, 1997 file written objections to any aspect of this
regulation (including the automatic revocation provision) and may also request
a hearing on those objections. Objections and hearing requests must be filed
with the Hearing Clerk, at the address given above (40 CFR 178.20). A copy of
the objections and/or hearing requests filed with the Hearing Clerk should be
submitted to the OPP docket for this rulemaking. The objections submitted must
specify the provisions of the regulation deemed objectionable and the grounds
for the objections (40 CFR 178.25). Each objection must be accompanied by the
fee prescribed by 40 CFR 180.33(i). If a hearing is requested, the objections
must include a statement of the factual issues on which a hearing is
requested, the requestor's contentions on such issues, and a summary of any
evidence relied upon by the requestor (40 CFR 178.27). A request for a hearing
will be granted if the Administrator determines that the material submitted
shows the following: There is genuine and substantial issue of fact; there is
a reasonable possibility that available evidence identified by the requestor
would, if established, resolve one or more of such issues in favor of the
requestor, taking into account uncontested claims or facts to the contrary;
and resolution of the factual issues in the manner sought by the requestor
would be adequate to justify the action requested (40 CFR 178.32). Information
submitted in connection with an objection or hearing request may be claimed
confidential by marking any part or all of that information as Confidential
Business Information (CBI). Information so marked will not be disclosed except
in accordance with procedures set forth in 40 CFR part 2. A copy of the
information that does not contain CBI must be submitted for inclusion in the
public record. Information not marked confidential may be disclosed publicly
by EPA without prior notice.

VIII. Public Docket

A record has been established for this rulemaking under docket number [OPP-
300460]. A public version of this record, which does not include any
information claimed as CBI, is available for inspection from 8:30 a.m. to 4
p.m., Monday through Friday, excluding legal holidays. The public record is
located in Room 1132 of the Public Response and Program Resources Branch,
Field Operations Division (7506C), Office of Pesticide Programs, Environmental
Protection Agency, Crystal Mall #2, 1921 Jefferson Davis Highway, Arlington,

Electronic comments may be sent directly to EPA at: opp-

Electronic comments must be submitted as an ASCII file avoiding the use of
special characters and any form of encryption.

The official record for this rulemaking, as well as the public version, as
described above, is kept in paper form. Accordingly, in the event there are
objections and hearing requests, EPA will transfer any copies of objections
and hearing requests received electronically into printed, paper form as they
are received and will place the paper copies in the official rulemaking
record. The official rulemaking record is the paper record maintained at the
Virginia address in "ADDRESSES" at the beginning of this document.

IX. Regulatory Assessment Requirements

Under Executive Order 12866 (58 FR 51735, October 4, 1993), this action is not
a "significant regulatory action" and, since this action does not impose any
information collection requirements as defined by the Paperwork Reduction Act,
44 U.S.C. 3501 et seq., it is not subject to review by the Office of
Management and Budget. This action does not impose any enforceable duty, or
contain any "unfunded mandates" as described in Title II of the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4), or require prior consultation as
specified by Executive Order 12875 (58 FR 58093, October 28, 1993), entitled
Enhancing the Intergovernmental Partnership, or special consideration as
required by Executive Order 12898 (59 FR 7629, February 16, 1994).

Because FFDCA section 408(l)(6) permits establishment of this regulation
without a notice of proposed rulemaking, the regulatory flexibility analysis
requirements of the Regulatory Flexibility Act, 5 U.S.C. 604(a), do not apply.

Under 5 U.S.C. 801(a)(1)(A) of the Administrative Procedure Act (APA) as
amended by the Small Business Regulatory Enforcement Fairness Act of 1996
(Title II of Pub. L. 104-121, 110 Stat. 847), EPA submitted a report
containing this rule and other required information to the U.S. Senate, the
U.S. House of Representatives and the Comptroller General of the General
Accounting Office prior to publication of the rule in today's Federal
Register. This rule is not a "major rule" as defined by 5 U.S.C. 804(2) of
the APA as amended.

List of Subjects in 40 CFR Part 180

Environmental protection, Administrative practice and procedure, Agricultural
commodities, Pesticides and pests, Reporting and recordkeeping requirements.

Dated: February 28, 1997.

Peter Caulkins,

Acting Director, Office of Pesticide Programs.
Therefore, 40 CFR Chapter I is amended as follows:


1. The authority citation for part 180 continues to read as follows:
Authority: 21 U.S.C. 346a and 371.

2. In Sec. 180.472, in paragraph (d), by adding alphabetically the following
entry to the table:

Sec. 180.472 Imidacloprid; tolerances for residues.

                                   Parts per         Expiration/
Commodity                          million           Revocation Date

Vegetables, Cucurbits                0.2             March 31, 1998

[FR Doc. 97-6654 Filed 3-18-97; 8:45 am]