[Federal Register Volume 63, Number 57 (Wednesday, March 25, 1998)]
[Rules and Regulations]
[Pages 14371-14378]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-7646]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[OPP-300628; FRL-5778-3]
RIN 2070-AB78


Imidacloprid; Pesticide Tolerance

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This regulation establishes tolerances for residues of the 
insecticide 1-[(6-chloro-3-pyridinyl)methyl]-N-nitro-2-
imidazolidinimine and its metabolites in or on sorghum grain 0.05 parts 
per million (ppm), forage 0.10 ppm, and stover 0.10 ppm. Gustafson, 
Inc. submitted a petition to EPA under the Federal Food, Drug and 
Cosmetic Act (FFDCA), as amended by the Food Quality Protection Act of 
1996 (Pub. L. 104-170) requesting these tolerances.

DATES: This regulation is effective March 25, 1998. Objections and 
requests for hearings must be received by EPA on or before May 26, 
1998.
ADDRESSES: Written objections and hearing requests, identified by the 
document control number, [OPP-300628], 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 
document control number, [OPP-300628], must also be submitted to: 
Public Information and Records Integrity Branch, Information Resources 
and Services Division (7502C), 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. 119, 
CM #2, 1921 Jefferson Davis Hwy., 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: [email protected]. 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 5.1/6.1 
file format or ASCII file format. All copies of objections and hearing 
requests in electronic form must be identified by the document control 
number [OPP-300628]. 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 Libraries.

FOR FURTHER INFORMATION CONTACT: By mail: Elizabeth T. Haeberer, 
Registration Division (7505C), Office of Pesticide Programs, 
Environmental Protection Agency, 401 M St., SW., Washington, DC 20460. 
Office location, telephone number, and e-mail address: Crystal Mall #2, 
1921 Jefferson Davis Hwy., Arlington, VA, (703) 308-2891, e-mail: 
[email protected].

SUPPLEMENTARY INFORMATION: In the Federal Register of October 29, 1997 
(62 FR 56171)(FRL-5752-2), EPA, issued a notice pursuant to section 408 
of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a(e) 
announcing the filing of a pesticide petition (PP 4F4415) by Gustafson, 
Inc., 1400 Preston Road, Suite 400, Plano, Texas 75093, to establish 
tolerances for the residues of the insecticide 1-[(6-chloro-3-
pyridinyl)methyl]-N-nitro-2-imidazolidiinimine in or on sorgum grain at 
0.05 parts per million (ppm), forage 0.10 ppm, and stover 0.10 ppm. 
This notice included a summary of the petition prepared by Gustafson, 
Inc., the registrant. There were no comments received in response to 
the notice of filing.
    The petition requested that 40 CFR 180.472(a) be amended by 
establishing tolerances for the insecticide, 1-[(6-chloro-3-
pyridinyl)methyl]-N-nitro-2-imidazolidiinimine, in or on sorghum grain, 
forage, and stover at 0.05, 0.10, and 0.10 ppm respectively.

I. Risk Assessment and Statutory Findings

    EPA establishes maximum legal levels (tolerances) for pesticide 
residues on food under section 408 of the FFDCA. EPA performs a number 
of analyses to determine the risk from aggregate exposure to pesticide 
residues. For further discussion of the regulatory requirements of 
section 408 and a complete description of the risk assessment process, 
see the Final Rule on Bifenthrin Pesticide Tolerances in the Federal 
Register, of November 26, 1997, (62 FR 62961-62970)(FRL-5754-7).

II. Aggregate Risk Assessment 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, EPA has sufficient data to assess the hazards of 1-[(6-
chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimine and its 
metabolites containing the 6-chloropyridinyl moiety, all calculated as 
imidacloprid, and to make a determination on aggregate exposure, 
consistent with section 408(b)(2), for a tolerance for 1-[(6-chloro-3-
pyridinyl)methyl]-N-nitro-2-imidazolidinimine and its metabolites 
containing the 6-chloropyridinyl

[[Page 14372]]

moiety, all calculated as imidacloprid, in or on sorghum grain, forage, 
and stover at 0.05, 0.10, and 0.10 ppm respectively. EPA's assessment 
of the dietary exposures and risks associated with establishing the 
tolerance follows.

A. Toxicological Profile

    EPA has evaluated the available toxicity data and considered its 
validity, completeness, and reliability as well as the relationship of 
the results of the studies to human risk. EPA has also considered 
available information concerning the variability of the sensitivities 
of major identifiable subgroups of consumers, including infants and 
children. The nature of the toxic effects caused by 1-[(6-chloro-3-
pyridinyl)methyl]-N-nitro-2-imidazolidinimine and its metabolites 
containing the 6-chloropyridinyl moiety are discussed below.
    1. A battery of acute toxicity studies placing technical 
imidacloprid in Toxicity Category II for oral LD50, Category 
IV for dermal LD50, inhalation LC50, eye 
iritation and dermal irritation. Imidacloprid is a non-sensitizer.
    2. In an acute neurotoxicity study, groups of Sprague-Dawley rats 
(18/sex/dose) were given a single oral administration of imidacloprid 
(97.6%) in 0.5% methylcellulose with 0.4% Tween 80 in deionized water 
at 0, 42, 151 or 307 mg/kg. Parameters evaluated included: clinical 
pathology (6/sex/dose); Functional Observation Battery (FOB) 
measurements (12/sex/dose); and neuropathology (6/sex/dose). FOB 
measurements were made approximately 90 minutes post dosing, and on 
days 7 and 14. Motor activity measurements were made at approximately 
2.5 hours post dosing.
    At 307 mg/kg/day, 4/18 males and 10/18 females died and both sexes 
of rats at this dose exhibited decreased numbers of rears, grip 
strength (forelimb and hindlimb) and response to stimuli (auditory, 
touch, or tail pinch) as well as increased gait abnormalities, righting 
reflex impairments and body temperatures. These symptoms regressed by 
day 5. At 151 milligram/kilograms/day (mg/kg/day), cage side FOB 
assessments revealed tremors in one male and one female and red nasal 
staining in one male. On the day of dosing, a dose-related decrease in 
total session motor activity was observed in males at 151 mg/kg/day 
(25% decrease) and 307 mg/kg/day (73%) and in females at all dose 
levels with the decreases (25, 48, and 81%, respectively at 42, 151 and 
307 mg/kg/day) reaching statistical significance (p <0.05) at 151 and 
307 mg/kg/day dose levels. Decreases in motor activity were seen at all 
time intervals. Total session locomotor activity was also decreased to 
about the same percentage difference but statistical significance was 
not reported. On days 7 and 14, decreases (not statistically 
significant) were still observed in motor and locomotor activity in 
surviving high-dose males. The lowest-observed-effect level (LOEL) was 
42 mg/kg based on the decrease in motor and locomotor activities 
observed in females; a no-observed-effect level (NOEL) was not 
established.
    3. In a subchronic oral toxicity study, groups of Fischer 344 rats 
(12/sex/dose) were fed diets containing imidacloprid (98.8%) at 0, 150, 
1,000, or 3,000 ppm (0, 9.3, 63.3, or 196 mg/kg/day in males and 0, 
10.5, 69.3 or 213 mg/kg/day in females, respectively) for 90 days. No 
treatment-related effects were seen at 150 ppm. Treatment-related 
effects included decreases in body weight gain during the first 4 weeks 
of the study at 1,000 ppm (22% in males and 18% in females) and 3,000 
ppm (50% in males and 25% in females) with an associated decrease in 
forelimb grip strength especially in males. The NOEL was 150 ppm (9.3 
and 10.5 mg/kg/day in males and females, respectively) and the LOEL was 
1,000 ppm (63.3 and 69.3 mg/kg/day in males and females, respectively).
    4. In a subchronic dermal toxicity study, groups of 5 male and 5 
female New Zealand White rabbits received repeated dermal applications 
of imidacloprid (95%) at 1,000 mg/kg/day (Limit Dose), 6 hours/day, 5 
days/week for three weeks. No dermal or systemic toxicity was seen. For 
systemic and dermal toxicity, the NOEL was > 1,000 mg/kg/day; a LOEL 
was not established.
    5. In a rat inhalation study (28-day study in which rats were 
exposed 6 hours/day, 5 days a week for 4 weeks), the no observable 
effect concentration (NOEC) for imidacloprid was 5.5 mg/m3.
    6. In a chronic oral toxicity study, groups of beagle dogs (4/sex/
dose) were fed diets containing imidacloprid (94.9%) at 0, 200 or 
1,250/2,500 ppm (0, 6.1, 15 or 41/72 mg/kg/day, respectively) for 52 
weeks. The 1,250 ppm dose was increased to 2,500 ppm from week 17 
onwards. The threshold NOEL was 1250 ppm (41 mg/kg/day). The LOEL was 
2,500 ppm (72 mg/kg/day) based on increased cytochrome-P-450 levels in 
both sexes and was considered to be a threshold dose. Due to the lack 
of toxicity at 1,250 ppm, a NOEL was not established in this study; 
following the dose increase to the 2,500 ppm level, toxicity was 
observed, thus making 1,250 ppm the threshold NOEL and 2,500 ppm the 
threshold LOEL.
    7. In a combined chronic toxicity/carcinogenicity study, groups of 
Bor WISW rats (50/sex/dose) received imidacloprid (95.3%) at 0, 100, 
300 or 900 ppm (0, 5.7, 16.9 or 51.3 mg/kg/day in males and 0, 7.6, 
24.9, or 73 mg/kg/day in females, respectively) for 104 weeks. In 
another study, rats of the same strain (50/sex) received imidacloprid 
at 0 or 1,800 ppm (0, 102.6 and 143.7 mg/kg/day in males and females, 
respectively) for 104 weeks. For chronic toxicity, the NOEL was 100 ppm 
(5.7 mg/kg/day) and the LOEL was 300 ppm (16.9 mg/kg/day) based on 
decreased body weight gains in females and increased thyroid lesions in 
males. There was no evidence of carcinogenicity in either sex.
    8. In a carcinogenicity study groups of B6C3F1 mice (50/sex/dose) 
were fed diets containing imidacloprid (95%) at 0, 100, 330 or 1,000 
ppm (0, 20, 66 or 208 mg/kg/day in males and 0, 30, 104 or 274 mg/kg/
day in females, respectively) for 2 years. In a supplementary study 
conducted to evaluate the adequacy of the high dose tested in the main 
study, the same strain of mice (50/sex) received 0 or 2,000 ppm (414 
and 424 mg/kg/day in males and females, respectively) for the same time 
period. For chronic toxicity, the NOEL was 1,000 ppm (208 mg/kg/day). 
The LOEL was 2,000 ppm (414 mg/kg/day) based on decreased body weight 
gain, food consumption and water consumption. There was no evidence of 
carcinogenicity in either sex.
    9. In a developmental toxicity study with Sprague-Dawley rats, 
groups of pregnant animals (25/group) received oral administration of 
imidacloprid (94.2%) at 0, 10, 30, or 100 mg/kg/day during gestation 
days 6 through 16. Maternal toxicity was manifested as decreased body 
weight gain at all dose levels and reduced food consumption at 100 mg/
kg/day. No treatment-related effects were seen in any of the 
reproductive parameters (i.e., cesarean section evaluation). At 100 mg/
kg/day, developmental toxicity manifested as wavy ribs (fetus =7/149 in 
treated vs. 2/158 in controls and litters, 4/25 vs. 1/25). For maternal 
toxicity, the LOEL was 10 mg/kg/day lowest dose tested (LDT) based on 
decreased body weight gain; a NOEL was not established. For 
developmental toxicity, the NOEL was 30 mg/kg/day and the LOEL was 100 
mg/kg/day based on increased wavy ribs.
    10. In a developmental toxicity study with Chinchilla rabbits, 
groups of 16 pregnant does were given oral doses of imidacloprid 
(94.2%) at 0, 8, 24 or 72 mg/kg/day during gestation days 6 through 18. 
For maternal toxicity, the NOEL was 24 mg/kg/day and the LOEL was 72 
mg/kg/day based on mortality,

[[Page 14373]]

decreased body weight gain, increased resorptions, and increased 
abortions. For developmental toxicity, the NOEL was 24 mg/kg/day and 
the LOEL was 72 mg/kg/day based on decreased fetal body weight, 
increased resorptions, and increased skeletal abnormalities.
    11. In a 2-generation reproductive toxicity study, imidacloprid 
(95.3%) was administered to Wistar/Han rats at dietary levels of 0, 
100, 250, or 700 ppm (0, 7.3, 18.3, or 52.0 mg/kg/day for males and 0, 
8.0, 20.5, or 57.4 mg/kg/day for females). For parental/systemic/
reproductive toxicity, the NOEL was 250 ppm (18.3 mg/kg/day) and the 
LOEL was 750 ppm (52 mg/kg/day), based on decreases in body weight in 
both sexes in both generations. Based on these factors, the Data 
Evaluation Record should be revised to indicate the parental/systemic/
reproductive NOEL and LOEL to be 250 and 700 ppm, respectively, based 
upon the body weight decrements observed in both sexes in both 
generations.
    12. Studies on gene mutation and other genotoxic effects: an Ames 
Salmonella Assay which was negative up to 5,500 g/plate 
concentration; recombination assay-yeast, negative for cross-over in 
yeast up to 10,000 g; In Vivo Chromasomal Aberration, negative 
for chromosome breakage up to 2,000 g/ml; In Vitro Chromasomal 
Aberrations, positive at 500 g/ml -S9 and 1,300 g/ml 
+S9, both toxic doses (acceptable study); In Vivo Sister Chromatid 
assay, negative up to 2,000 g/ml; In Vitro Cytogenetics-CHO 
cells, negative for producing forward mutation in CHO (mammalian) cells 
treated up to 1222 g/ml; Micronucleus - mouse, negative up to 
(toxic) 50 g/ml (ip); DNA repair test, negative for cross-over 
in yeast up to 10,000 g; HGPRT assay-CHO, negative up to 2,000 
g/ml. Mutagenicity studies have demonstrated that imidacloprid 
is non-mutagenic both in vivo and in vitro.

B. Toxicological Endpoints

    1. Special sensitivity to 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. These studies are described in unit II A. of this 
document. The developmental toxicity data demonstrated no increased 
sensitivity of rats or rabbits to in utero exposure to imidacloprid. In 
addition, the multi-generation reproductive toxicity study data did not 
identify any increased sensitivity of rats to in utero or postnatal 
exposure. Parental NOELs were lower or equivalent to developmental or 
offspring NOELs. The developmental toxicity studies are designed to 
evaluate adverse effects on the developing organism resulting from 
maternal pesticide exposure gestation. Reproduction studies provide 
information relating to effects from exposure to the pesticide on the 
reproductive capability of mating animals and data on systemic 
toxicity.
    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 pre-and post-natal toxicity and the 
completeness of the database unless EPA determines that a different 
margin of safety will be safe for infants and children. Margins of 
safety are incorporated into EPA risk assessments either directly 
through use of a MOE analysis or through using uncertainty (safety) 
factors in calculating a dose level that poses no appreciable risk to 
humans. EPA believes that reliable data support using the standard 
uncertainty factor (usually 100 for combined inter- and intra-species 
variability)) and not the additional tenfold MOE/uncertainty factor 
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/safety factor.
    Although developmental toxicity studies showed no increased 
sensitivity in fetuses as compared to maternal animals following in 
utero exposures in rats and rabbits, no increased sensitivity in pups 
as compared to adults was seen in the two generation reproduction 
toxicity study in rats, and the toxicology data base is complete as to 
core requirements, the Agency determined that the additional safety 
factor for the protection of infants and children will be retained but 
reduced to 3x based on the following weight-of-the-evidence 
considerations relating to potential sensitivity and completeness of 
the data:
    (i) There is concern for structure activity relationship. 
Imidacloprid, a chloronicotinyl compound, is an analog to nicotine and 
studies in the published literature suggests that nicotine, when 
administered causes developmental toxicity, including functional 
deficits, in animals and/or humans that are exposed in utero.
    (ii) There is evidence that imidacloprid administration causes 
neurotoxicity following a single oral dose in the acute study and 
alterations in brain weight in rats in the 2-year carcinogenicity 
study.
    (iii) The concern for structure activity relationship along with 
the evidence of neurotoxicity dictates the need of a developmental 
neurotoxicity study for assessment of potential alterations on 
functional development.
    Because a developmental neurotoxicity study potentially relates to 
both acute and chronic effects in both the mother and the fetus, the 
additional UF for FQPA is being applied for all population subgroups, 
and both acute and chronic risk.
    2. Acute toxicity. Acute dietary risk assessment is required for 
all population subgroups. LOEL=42 mg/kg/day based on decreased motor 
activity in female rats; MOE=300, as discussed above. Conventionally, 
when a LOEL from the critical study is used for risk assessment, an 
additional UF will be applied. For acute risk assessment with 
imidacloprid, however, the Committee determined that an additional 
uncertainty factor is not necessary because: (i) of the low confidence 
in the endpoint based on the minimal nature of the effect (decreased 
motor activity only in females); (ii) this effect was seen in adult 
rats; and (iii) the same effect was not seen in the subchronic toxicity 
study following repeated doses.
    3. Short - and intermediate - term toxicity. In a dermal toxicity 
study, groups of 5 male and 5 female New Zealand White rabbits received 
repeated dermal applications of imidacloprid (95%) at 1,000 mg/kg/day 
(Limit Dose), 6 hours/day, 5 days/week for three weeks. No dermal or 
systemic toxicity was seen. For systemic and dermal toxicity, the NOEL 
was > 1,000 mg/kg/day; a LOEL was not established (MRID No. 42256329).
    In an oral toxicity study, groups of Fischer 344 rats (12/sex/dose) 
were fed diets containing imidacloprid (98.8%) at 0, 150, 1,000, or 
3,000 ppm (0, 9.3, 63.3, or 196 mg/kg/day in males and 0, 10.5, 69.3 or 
213 mg/kg/day in females, respectively) for 90 days. No treatment-
related effects were seen at 150 ppm. Treatment-related effects 
included decreases in body weight gain during the first four weeks of 
the study at 1,000 ppm (22% in males and 18% in females) and 3,000 ppm 
(50% in males and 25% in females) with an associated decrease in 
forelimb grip strength especially in males. The NOEL was 150 ppm (9.3 
and 10.5 mg/kg/day in males and females, respectively) and the LOEL was 
1,000 ppm (63.3 and 69.3 mg/kg/day in males and females, respectively) 
(MRID No. 43286401).
    In a rat inhalation study (28-day study in which rats were exposed 
6 hours/day, 5 days a week for 4 weeks), the no observable effect 
concentration (NOEC)

[[Page 14374]]

for imidacloprid was 5.5 mg/m3 (MRID No. 422730-01).
    4.  Chronic toxicity. EPA has established the RfD for 1-[(6-chloro-
3-pyridinyl)methyl]-N-nitro-2-imidazolidinimine at 0.019 mg/kg/day. 
This RfD is based upon increased number of thyroid lesions in male and 
decreased body weight gains in female Bor WISW rats, with a NOEL of 5.7 
mg/kg/day, and LOEL of 16.9/24.9 mg/kg/day (males and females 
respectively); UF=300, as discussed above.
    5. Carcinogenicity. This chemical has been classified as a Group E 
- no evidence of carcinogenicity for humans. A cancer risk assessment 
is not required.

C. Exposures and Risks

    1. From food and feed uses. Tolerances have been established 40 CFR 
180.472(a) for the combined residues of 1-[(6-chloro-3-
pyridinyl)methyl]-N-nitro-2-imidazolidinimine and its metabolites, in 
or on a variety of raw agricultural commodities. Risk assessments were 
conducted by EPA to assess dietary exposures and risks from 
imidacloprid as follows:
    i.  Acute exposure and risk. Acute dietary risk assessments are 
performed for a food-use pesticide if a toxicological study has 
indicated the possibility of an effect of concern occurring as a result 
of a one day or single exposure. An acute dietary risk assessment is 
required for all population subgroups.
    This acute dietary (food) risk assessment used the Theoretical 
Maximum Residue Contribution (TMRC). Resulting exposure values and 
Margins of Exposure (MOEs; MOE = Acute Endpoint  Exposure) are 
shown below.

----------------------------------------------------------------------------------------------------------------
                                         High-End\1\                         Exposure @ 99th                    
         Population Subgroup           Exposure (mg/kg/        MOE\2\       Percentile (mg/kg/        MOE       
                                             day)                                  day)                         
----------------------------------------------------------------------------------------------------------------
U.S. population (48 states).........               0.10                420            0.05\3\                840
Infants (< 1 yr)....................               0.15                280               0.10                420
Children (1-6 yrs)..................               0.15                280               0.10                420
Females (13+ yrs)...................               0.05                840               0.04               1050
Males (13+ yrs).....................               0.10                420               0.05               840 
----------------------------------------------------------------------------------------------------------------
\1\ > 99.5th Percentile.                                                                                        
\2\ MOE = Margin of Exposure.                                                                                   
\3\ @ 98th Percentile (U.S. Pop. only).                                                                         

    These results should be viewed as a very conservative risk 
estimate; refinement using anticipated residue values and percent crop-
treated information in conjunction with Monte Carlo analysis would 
result in a lower estimate (i.e., higher MOE) of acute dietary 
exposure.
    ii. Chronic exposure and risk. The endpoint selected for chronic 
risk assessment is decreased body weight gains in females and increased 
thyroid lesions observed at 7.6 mg/kg/day in male rats in a combined 
chronic toxicity/carcinogenicity study. The NOEL was 5.7 mg/kg/day. A 
UF of 300 is required as discussed above.
    In conducting this chronic dietary (food) risk assessment, EPA 
used: (i) tolerance level residues for pecans, grain sorghum, and all 
other commodities with published, permanent or time-limited 
imidacloprid tolerances, the pending proposed tolerance for the citrus 
crop group; and, (ii) percent crop-treated (%CT) information on some of 
these crops. Thus, this risk assessment should be viewed as partially 
refined. Further refinement using anticipated residue values and 
additional %CT information would result in a lower estimate of chronic 
dietary exposure.
    The results are summarized below.

------------------------------------------------------------------------
                                               Exposure(mg/             
             Population Subgroup                  kg/day)        %RfD   
------------------------------------------------------------------------
U.S. Population (48 states)                        0.003596           19
Nursing Infants (<1 year old)                      0.002824           15
Non-Nursing Infants (<1 year old)                  0.009983           53
Children (1-6 years old)                           0.007514           40
Children (7-12 years old)                          0.005305           28
U.S. Population - Fall Season                      0.003716           20
Northeast Region                                   0.003771           20
Western Region                                     0.003842           20
Hispanics                                          0.003879           20
Non-Hispanic Others                                0.003906           21
------------------------------------------------------------------------

    The subgroups listed above are: (1) the U.S. population (48 
states); (2) those for infants and children; and, (3) the other 
subgroups for which the percentage of the RfD occupied is greater than 
that occupied by the subgroup U.S. population (48 states).
    Section 408(b)(2)(F) states that the Agency may use data on the 
actual percent of food treated for assessing chronic dietary risk only 
if the Agency can make the following findings: (1) that the data used 
are reliable and provide a valid basis for showing the percentage of 
food derived from a crop that is likely to contain residues; (2) that 
the exposure estimate does not underestimate the exposure for any 
significant subpopulation and; (3) where data on regional pesticide use 
and food consumption are available, that the exposure estimate does not 
understate exposure for any regional population. In addition, the 
Agency must provide for periodic evaluation of any estimates used. To 
provide for the periodic evaluation of these estimates of percent crop 
treated as required by the section 408(b)(2)(F), EPA may require 
registrants to submit data on percent crop treated.
    The Agency used percent crop treated (PCT) information as follows. 
A routine chronic dietary exposure analysis for imidacloprid was based 
on likely maximum percent of crop treated as follows: 6% grapefruits, 
3% oranges, 13% other citrus, 19% apples, 2% pears, 11% grapes, 30% 
eggplants/peppers, 32% head lettuce, 21% cole crops, 15% melons, 10% 
tomatoes, 6% cotton.
    The Agency believes that the three conditions listed above have 
been met. With respect to (1), EPA finds that the PCT information 
described above for imidacloprid is reliable and has a valid basis, The 
Agency has utilized the latest statistical data from RFF (Resources For 
The Future), DOANE, and USDA, the best available sources for such 
information. Concerning (2) and (3), regional consumption information 
and consumption information for significant subpopulations is taken 
into account through EPA's computer-based model

[[Page 14375]]

for evaluating the exposure of significant subpopulations including 
several regional groups. Use of this consumption information in EPA's 
risk assessment process ensures that EPA's exposure estimate does not 
understate exposure for any significant subpopulation group and allows 
the Agency to be reasonably certain that no regional population is 
exposed to residue levels higher than those estimated by the Agency. 
Other than data available through national food consumption surveys, 
EPA does not have available information on the consumption of food 
bearing imidacloprid in a particular area.
    2. From drinking water. EPA used the estimated environmental 
concentration (EEC) data to calculate acute and chronic exposure 
estimates for imidacloprid in surface water using the following 
formulas:
    Adult Male: Exposure (mg/kg/day) = (chemical concentration in 
g/L in consumed water) * (10-3 mg/g) 
 (70 kg body weight) * (2 L water consumed/day)
    Adult Female: Exposure (mg/kg/day) = (chemical concentration in g/L 
in consumed water) * (10-3 mg/g)  (60 kg body weight) 
* (2 L water consumed/day)
    Child (1-6 years): Exposure (mg/kg/day) = (chemical concentration 
in g/L in consumed water) * (10-3 mg/g) 
 (10 kg body weight) * (1 L water consumed/day)
    Acute MOE: Acute Endpoint (42 mg/kg/day)  Exposure (mg/kg/
day)
    Chronic Risk (%RfD): Exposure (mg/kg/day)  RfD (0.019 mg/
kg/day) * 100
    The 2 liters (L) of drinking water consumed/day by adults and the 1 
L per day consumed by children are default assumptions used by the 
Office of Water. The Agency's default body weights for males is 70 kg 
and for females, 60 kg. HED's default body weight for children is 10 
kg.
    The results are summarized below:

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Acute Scenario                                          Chronic Scenario                   
                                       -----------------------------------------------------------------------------------------------------------------
          Population Subgroup            g/L in    Exposure (mg/kg/                      g/L in    Exposure (mg/kg/                   
                                          Water Consumed          day)               MOE           Water Consumed          day)              % RfD      
--------------------------------------------------------------------------------------------------------------------------------------------------------
Adult male............................               50.9            0.00145             29,000               19.1            0.00055                2.9
Adult Female..........................               50.9            0.00170             24,700               19.1            0.00064                3.4
Child (1-6 yrs).......................               50.9            0.00509              8,250               19.1            0.00191               10.1
--------------------------------------------------------------------------------------------------------------------------------------------------------

    These results should be viewed as a very conservative risk 
estimate. Refinement by applying factors to account for the percent of 
acreage planted in a watershed, the percent of crop-treated, and the 
water flow rate would result in a lower estimate of acute and chronic 
exposure from consumption of surface waters containing imidacloprid 
residues.
    3. From non-occupational non-dietary exposure. Imidacloprid is 
currently registered for use on the following residential non-food 
sites: ornamentals (e.g., flowering and foliage plants, ground covers, 
turf, lawns, et al.), tobacco, golf courses, walkways, recreational 
areas, bathrooms, household or domestic dwellings (indoor/outdoor), 
cats/dogs, and wood protection treatment to buildings. Available data 
do not demonstrate that imidacloprid has either dermal or inhalation 
toxicity potential, therefore, non-occupational non-dietary risk 
assessments are not required. Since data show no toxicity from short 
term exposure via the dermal or inhalation route, the Agency feels 
there is no contribution to toxicity from these routes of exposure, and 
no increase in aggregate risk is anticipated from this exposure. 
Therefore residential exposure does not aggregate with dietary exposure 
for any risk assessments.
    4. 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.'' An explanation of the current Agency 
approach to assessment of pesticides with a common mechanism of 
toxicity may be found in the Final Rule on Bifenthrin Pesticide 
Tolerances in the Federal Register, of November 26, 1997, (62 FR 62961-
62970)(FRL-5754-7).
    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. Imidacloprid is the sole member to date 
of the new chloronicotinyl class of pesticides.

D. Aggregate Risks and Determination of Safety for U.S. Population, 
Infants and Children

    1. Acute risk. Acute aggregate dietary risk (combined food and 
water) is estimated by adding the acute exposures to food and water 
(highest of ground or surface water) and comparing this exposure to the 
acute dietary endpoint:
    Aggregate MOEACUTE = acute dietary endpoint  
aggregate exposure.
    The results of the acute aggregate dietary (food and water) risk 
assessment are given below.

----------------------------------------------------------------------------------------------------------------
                                                           Exposure from        Aggregate                       
         Population Subgroup            Exposure from    Surface Water (mg/  Exposure (mg/kg/   Aggregate Acute 
                                       Food (mg/kg/day)       kg/day)              day)               MOE       
----------------------------------------------------------------------------------------------------------------
U.S. population (48 states).........              0.101             0.0023              0.102                412
Infants (<1 yr).....................              0.102             0.0054              0.105               4005
Children (1-6 yrs)..................              0.102              0.005              0.105               4005
Females (13+ yrs)...................              0.051              0.002              0.052                808
Males (13+ yrs).....................              0.101              0.002              0.102               412 
----------------------------------------------------------------------------------------------------------------
\1\ High-End Exposure (>99.5th Percentile).                                                                     
\2\ Exposure @ 99th percentile; high-end exposure = 0.15 mg/kg/day.                                             

[[Page 14376]]

                                                                                                                
\3\ 3 Exposure value used was that calculated for females (13+ years) and males (13+ years).                    
\4\ Exposure value used was that calculated for children (1-6 years).                                           
\5\ Based on exposure @ 99th percentile; MOE is 271 @ high-end exposure (>99.5th percentile).                   

    For imidacloprid, an (aggregate) acute dietary MOE of 
300 is needed to protect the safety of all population 
subgroups. The aggregate MOEs for the general population, females (13+ 
years), and males (13+ years) are >400 at the high-end exposure. The 
aggregate MOEs for infants and children are calculated to be 400 at the 
99th percentile of exposure, and 271 at the high-end exposure (>99.5th 
percentile).
    In conducting the acute dietary (food) risk assessment the 
Theoretical Maximum Residue Contribution (TMRC) was used. There was no 
refinement using anticipated residue values and percent crop-treated 
information in conjunction with Monte Carlo analysis which would result 
in a much lower estimate (i.e., higher MOE) of acute dietary exposure.
    Because of the very conservative nature of the assumptions used in 
these calculations, and the fact that refinement would lower the risk 
estimates (i.e., result in higher MOE values) for both 
MOEfood and MOEwater, EPA concludes that there is 
a reasonable certainty that no harm will result to infants, children, 
or adults from acute aggregate risk (food and water) exposure to 
imidacloprid residues.
    2. Chronic risk. Dermal and inhalation exposure endpoints were not 
selected due to the demonstrated absence of toxicity, thus, there is no 
residential component for assessing chronic aggregate exposure and 
risk.
    In conducting the chronic dietary (food) risk assessment, EPA used: 
(i) tolerance level residues for pecans, grain sorghum, and all other 
commodities with published, permanent or time-limited imidacloprid 
tolerances, the pending proposed tolerance for the citrus crop group; 
and, (ii) percent crop-treated (%CT) information on some of these 
crops. Thus, this risk assessment should be viewed as partially 
refined. Further refinement using anticipated residue values and 
additional %CT information would result in a lower estimate of chronic 
dietary exposure.
    Chronic aggregate dietary risk (combined food and water) will be 
estimated by adding the chronic exposures to food and water (highest of 
ground or surface water) and comparing this exposure to the RfD:
    Aggregate %RfD Occupied = (aggregate exposure  RfD) x 100.
    The results of the chronic aggregate dietary (food and water) risk 
assessment are given below.

----------------------------------------------------------------------------------------------------------------
                                                           Exposure from        Aggregate                       
         Population Subgroup            Exposure from    Surface Water (mg/  Exposure (mg/kg/    % RfD Occupied 
                                       Food (mg/kg/day)       kg/day)              day)                         
----------------------------------------------------------------------------------------------------------------
U.S. population (48 states).........             0.0036            0.00061             0.0042                 22
Nursing infants (<1 yr old).........             0.0028            0.00192             0.0047                 25
Non-nursing infants (<1 yr old).....             0.0100            0.00192             0.0119                 63
Children (1-6 yrs old)..............             0.0075             0.0019             0.0094                 49
Children (7-12 yrs old).............             0.0053            0.00192             0.0072                38 
----------------------------------------------------------------------------------------------------------------
\1\ Used average value based on adult male (0.00055 mg/kg/day) and adult female (0.00064 mg/kg/day).            
\2\ Data not available; used the value for children (1-6 years).                                                

    This chronic aggregate dietary risk assessment is based on 
conservative exposure consumptions. Refinement of the assumptions used 
in estimating exposure from food and water sources would result in 
lower estimates of chronic aggregate dietary risk.
    The calculated results indicate that the aggregate dietary exposure 
to imidacloprid utilizes 22% of the RfD for the U.S. general 
population.
    For infants and children, the percentage of the RfD that is 
utilized by aggregate dietary exposure to imidacloprid ranges from 25% 
for nursing infants less than 1 year old, up to 63% for non-nursing 
infants less than 1 year old.
    The Agency generally has no concern for exposures below 100% 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.
    EPA concludes that there is a reasonable certainty that no harm 
will result to infants, children, or adults from chronic aggregate 
(food plus water) exposure to imidacloprid residues.
    3. Short - intermediate - term risk. Short - and intermediate - 
term aggregate exposure take into account chronic dietary food and 
water plus indoor and outdoor residuential exposure. This risk 
assessment is not required for imidacloprid.

E. Aggregate Cancer Risk for U.S. Population

    Imidacloprid has been classified as a Group E chemical, no evidence 
of carcinogenicity for humans, therefore, a cancer risk assessment is 
not required.

III. Other Considerations

A. Metabolism In Plants and Animals

    The nature of imidacloprid residues in plants and animals is 
adequately understood. The residue of concern is imidacloprid and its 
metabolites containing the 6-chloropyridinyl moiety, all expressed as 
parent, as specified in 40 CFR 180.472.

B. Analytical Enforcement Methodology

    Adequate enforcement methods are available for determination of the 
regulated imidacloprid residue in plant (Bayer GC/MS Method 00200 and 
Bayer HPLC-UV Confirmatory Method 00357) and animal (Bayer GC/MS Method 
00191) commodities. The limit of quantitaion (LOQ) is 0.05 ppm, and the 
limit of detection (LD) is 0.01 ppm for grain sorgum, sorghum forage 
and fodder. These methods have successfully completed EPA Tolerance 
Method Validation, and are awaiting publication in Pesticide Analytical 
Manual II (PAM II). In the interim, these methods are available from 
Calvin Furlow, EPA, OPP, IRSD, PIRIB.

C. Magnitude of Residues

    A total of three field residue trials were conducted in 1995 in 
three different states, located in Regions 6, 7, and 8. A single 
application of imidacloprid was made to seed at a rate of 1X. Two 
replicate samples of forage were harvested from each treated plot 90-
119 days after planting; samples of grain and fodder, 118-139 days. The 
samples were frozen and analyzed within 3 months of harvest, using the 
validated enforcement method. The average recovery was 82  
10% in grain,

[[Page 14377]]

79  4% in forage, and 83  6% in fodder. 
Analyses of the treated samples showed that the total residues of 
imidacloprid and its metabolites were <0.05 ppm. These results support 
tolerances for residues of imidacloprid and its metabolites at 0.05 ppm 
for sorghum grain, and for sorghum forage and fodder at 0.1 ppm.

D. Magnitude of the Residue in Processed Commodities

    There are no detectable total imidacloprid residues at or above the 
LOQ of 0.05 ppm in the rac sorghum grain from an exaggerated 2X seed 
treatment application, thus a sorghum processing study is not required.

E. Magnitude of Secondary Residues in Meat/Milk/Poultry/Eggs

    Based on the results of the imidacloprid bovine and poultry feeding 
studies, finite residues will occur in meat, milk, poultry, and eggs 
from the feeding of imidacloprid treated racs or their processed feed 
items from seed treatment uses. Adequate total imidacloprid secondary 
tolerances have been established at 0.1 ppm in milk, 0.3 ppm in meat, 
fat, and meat by-products of cattle, goats, hogs, horses, and sheep, 
0.02 ppm in eggs, and 0.05 ppm in meat, fat, and meat by-products of 
poultry, to cover this seed treatment use in/on sorgum.

F. Rotational Crop Restrictions.

    Adequate limited field rotational crop studies have been presented 
from 3 sites with an in-furrow soil application of the 2.5% granular 
formulation and soil aged 1, 4, 8, and 11 months before replanting with 
the cereal grains wheat or sorghum, turnips as the root crop, and 
mustard greens or spinach as the leafy vegetable. Total imidacloprid 
residues were at or about the minimum detection limit (MDL) of 0.01 ppm 
by 11 months. Total imidacloprid residues present would be less after 
12 months in cereal or small grains, root crops, or leafy vegetables. 
These limited field crop rotational studies with the 3 crop groups 
support an overall 12 month plant back restriction for no detectable 
residues to be present in rotated crops. No rotational crop 
imidacloprid tolerances are necessary with such a restriction.

G. International Residue Limits

    There are no CODEX or Mexican maximum residue limits (MRLs) for 
imidacloprid on any crop. There are Canadian MRLs for combined residues 
of imidacloprid plus metabolites with the 6-chlorophenyl moiety, but 
not on grain sorghum. International compatibility is thus not an issue.

IV. Conclusion

    Therefore, the tolerance is established for residues of 1-[(6-
chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimine and its 
metabolites in or on grain sorghum at 0.05 ppm, grain sorghum forage 
and stover at 0.10 ppm.

V. 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 26, 1998, file written objections to any 
aspect of this regulation 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 reasonablepossibility 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 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.

VI. Public Docket

    EPA has established a record for this rulemaking under docket 
control number [OPP-300628] (including any comments and data submitted 
electronically). A public version of this record, including printed, 
paper versions of electronic comments, 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 119 of the Public Information and Records 
Integrity Branch, Information Resources and Services Division (7502C), 
Office of Pesticide Programs, Environmental Protection Agency, Crystal 
Mall #2, 1921 Jefferson Davis Highway, Arlington, VA.
    Electronic comments may be sent directly to EPA at:
    [email protected].


    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 will be kept in paper form. Accordingly, 
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 which 
will also include all comments submitted directly in writing. The 
official rulemaking record is the paper record maintained at the 
Virginia address in ``ADDRESSES'' at the beginning of this document.

VII. Regulatory Assessment Requirements

    This final rule establishes tolerances for the residues of 
imidacloprid and its metabolites in or on grain sorghum at 0.05 ppm, 
grain sorghum forage and stover at 0.10 ppm under FFDCA section 408(d) 
in response to a petition submitted to the Agency. The Office of 
Management and Budget (OMB) has exempted these types of actions from 
review under Executive Order 12866, entitled Regulatory Planning and 
Review (58 FR 51735, October 4, 1993).

[[Page 14378]]

 This final rule does not contain any information collections subject 
to OMB approval under the Paperwork Reduction Act (PRA), 44 U.S.C. 3501 
et seq., or impose any enforceable duty or contain any unfunded mandate 
as described under Title II of the Unfunded Mandates Reform Act of 1995 
(UMRA) (Pub. L. 104-4). Nor does it require any prior consultation as 
specified by Executive Order 12875, entitled Enhancing the 
Intergovernmental Partnership (58 FR 58093, October 28, 1993), or 
special considerations as required by Executive Order 12898, entitled 
Federal Actions to Address Environmental Justice in Minority 
Populations and Low-Income Populations (59 FR 7629, February 16, 1994), 
or require OMB review in accordance with Executive Order 13045, 
entitled Protection of Children from Environmental Health Risks and 
Safety Risks (62 FR 19885, April 23, 1997).
    In addition, since these tolerances and exemptions that are 
established on the basis of a petition under FFDCA section 408(d), such 
as the tolerances for the residues of imidacloprid and its metabolites 
in or on grain sorghum at 0.05 ppm, grain sorghum forage and stover at 
0.10 ppm in this final rule, do not require the issuance of a proposed 
rule, the requirements of the Regulatory Flexibility Act (RFA) (5 
U.S.C. 601 et seq.) do not apply. Nevertheless, the Agency has 
previously assessed whether establishing tolerances, exemptions from 
tolerances, raising tolerance levels or expanding exemptions might 
adversely impact small entities and concluded, as a generic matter, 
that there is no adverse economic impact. The factual basis for the 
Agency's generic certification for tolerance actions published on May 
4, 1981 (46 FR 24950) and was provided to the Chief Counsel for 
Advocacy of the Small Business Administration.

VIII. Submission to Congress and the Comptroller General

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this rule and other 
required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. This rule is not a 
``major rule'' as defined by 5 U.S.C. 804(2).

List of Subjects in 40 CFR Part 180

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


    Dated: March 16, 1998

James Jones,

Director, Registration Division, Office of Pesticide Programs.
    Therefore, 40 CFR chapter I is amended as follows:

PART 180-[AMENDED]

    1. The authority citation for part 180 continues to read as 
follows:

    Authority: 21 U.S.C. 346a and 371.

    2. Section 180.472, paragraph (a) is amended by alphabetically 
adding the commodities to read as follows:


Sec. 180.472   Imidacloprid; tolerances for residues.

    (a) *    *    *

------------------------------------------------------------------------
              Commodity                        Parts per million        
------------------------------------------------------------------------
                                                                        
         *        *        *        *        *        *        *        
Grain, sorghum......................                                0.05
Grain, sorghum forage...............                                0.10
Grain, sorghum stover...............                                0.10
                                                                        
         *        *        *        *        *        *        *        
------------------------------------------------------------------------

*    *    *    *    *

[FR Doc. 98-7646 Filed 3-24-98; 8:45 am]
BILLING CODE 6560-50-F