Docket #: EPA-HQ-OPP-2009-0774 

COMPANY NOTICE OF FILING 

EPA Registration Division contact: Sidney Jackson, (703) 305-7610

Interregional Research Project No. 4 (IR-4)

PP9E7611

EPA has received a pesticide petition PP9E7611 from Interregional Research 

Project No. 4 (IR-4), 500 College Road East, Suite 201W, Princeton, NJ 08540 in 

cooperation with the registrant, Syngenta Crop Protection, Inc., 410 Swing Rd., 

Greensboro, NC 27419 proposing, pursuant to section 408(d) of the Federal Food, Drug, 

and Cosmetic Act (FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR part 180.275 by

establishing a tolerance for residues of Chlorothalonil in or on the raw agricultural 

commodity low growing berries subgroup 13-07G at 0.01 parts per million (ppm);

Bushberry subgroup 13-07B at 1 ppm; onion, bulb subgroup 13-07A at 0.5 ppm; 

and onion, green subgroup 13-07B at 5 ppm. EPA has determined that the petition 

contains data or information regarding the elements set forth in section 408 (d)(2) of 

FDDCA; however, EPA has not fully evaluated the sufficiency of the submitted data at 

this time or whether the data supports granting of the petition. Additional data may be 

needed before EPA rules on the petition.

A. Residue Chemistry

1. Plant metabolism. The metabolism of Chlorothalonil as well as 

the nature of the residues in plants is adequately understood for purposes of the 

proposed tolerance. Plant metabolism has been evaluated in five diverse crops: 

Carrots, celery, lettuce, snap beans, and tomatoes, which should serve to define the 

similar metabolism of Chlorothalonil in a wide range of crops. The qualitative 

nature of residues in plants for Chlorothalonil is adequately understood. The 

residue of concern is Chlorothalonil and its metabolite, 4-hydroxy2,5,6-trichloroisophthalonitrile (SDS-3701). Parent metabolite CGA64250 is the major compound found in crops.

2. Analytical method. An adequate residue analytical method (gas 

chromatography) is available for enforcement purposes. The method is 

listed in the Pesticide Analytical Manual (PAM) Vol. II (PAM II).

3. Magnitude of residues. All samples were analyzed for residues of 

Chlorothalonil and its metabolite SDS-3701 (R182281). The limit of quantitation 

(LOQ) for Chlorothalonil and SDS-3701 were 0.030 ppm.

i. Strawberries (low growing bush berries except cranberries): 

Eight field trials were conducted for this study. The first field trial (Florida 05-
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FL01 in EPA region 3) was conducted to determine treatment rate and pre-harvest 

intervals (PHIs) for the additional trials. The seven remaining trials were located in 

Florida (region 3), California (two trials, region 10), New York (region 1), New 

Jersey (region 2), Michigan (region 5), and Oregon (region 12).

Strawberries were collected from the 05-FL01 Florida treated plot at the nearly ripe 

stage, from 29 days after the fifth foliar application in TRT 06 to 62 days after the 

transplant dip only (TRT 07). Strawberries were collected from the 05-FL49 

Florida and from all California trials at the marketable stage, from 70 days after the 

second application (TRT 12 in 05-FL49) to 175 days after the transplant dip only 

(TRT 07 in 05 CA*157). Strawberries were collected from the New York, New 

Jersey, Michigan, and Oregon treated plots at the marketable stage, from 53 days 

after the final application (TRT 15 in 05-NY21) to 90 days after the dormant spray 

only (TRT 13 in 05 OR18). 

The results from the trials show that no residues of chlorothalonil or SDS-3701

(R182281) were observed in any strawberry sample above the LLMV (0.030 ppm 

for GC/ECD and 0.010 ppm for GC/MSD), regardless of treatment scenario or PHI.

ii. Bushberry subgroup 13-07B

The existing tolerance for blueberries is being used to request a tolerance on Crop 

Subgroup 13-07B; Bushberry subgroup.

iii. Onion subgroups 3-07A and 3-07B

The existing tolerance for bulb onion is being used to request a tolerance on Crop 

subgroup 3-07A; Onion, bulb subgroup and the existing tolerance for green onion is 

being used to request a tolerance on Crop subgroup 3-07B; Onion, green subgroup.

B. Toxicological Profile

1. Acute toxicity. An assessment of the toxic effects caused by Chlorothalonil

is discussed in Unit III.A. and Unit III.B. in the Federal Register of 

December 3, 2008 (FR Volume 73, Number 233) (FRL-8387-9).

2. Genotoxicty. An assessment of the toxic effects caused by Chlorothalonil is 

discussed in Unit III.A. and Unit III.B. in the Federal Register of 

December 3, 2008 (FR Volume 73, Number 233) (FRL-8387-9).

3. Reproductive and developmental toxicity. . An assessment of the toxic effects 

caused by Chlorothalonil is discussed in Unit III.A. and Unit III.B. in the Federal 

Register of December 3, 2008 (FR Volume 73, Number 233) (FRL-8387-9).

4. Subchronic toxicity. . An assessment of the toxic effects caused by 

Chlorothalonil is discussed in Unit III.A. and Unit III.B. in the Federal Register of 

December 3, 2008 (FR Volume 73, Number 233) (FRL-8387-9).

5. Chronic toxicity. . An assessment of the toxic effects caused by 
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Chlorothalonil is discussed in Unit III.A. and Unit III.B. in the Federal Register of 

December 3, 2008 (FR Volume 73, Number 233) (FRL-8387-9)

6. Animal metabolism. The metabolism of chlorothalonil in the rat 

is adequately understood.

7. Metabolite toxicology. The residues of concern for tolerance 

setting purposes in or on raw agricultural commodity are the parent 

compound and its metabolite, 4-hydroxy-2,5,6-trichloroisophthalonitrile 

(SDS-3701). The residue of concern in meat and milk is SDS-3701.

8. Endocrine disruption. Chlorothalonil does not belong to a class 

of chemicals known or suspected of having adverse effects on the 

endocrine system. Developmental toxicity studies in rats and rabbits 

and a reproduction study in rats gave no indication that chlorothalonil 

might have any effects on endocrine function related to development and 

reproduction. The subchronic and chronic studies also showed no evidence of a 

long-term effect related to the endocrine system.

C. Aggregate Exposure

1. Dietary exposure. Tier II/III chronic aggregate and short-term aggregate 

exposure evaluations were made for chlorothalonil using the Dietary Exposure 

Evaluation Model software with the Food Commodity Intake Database (DEEMFCIDTM, version 2.16) from Exponent. Empirically derived processing factors were 

used for beans (snap, babyfood and cooked, 0.05X), cabbage (0.2X), carrots 

(babyfood, 0.005X), cherries (babyfood, 0.05X), cherry juice (0.075X), cocoa (0.1X), 

coffee (0.1X), cranberry juice (0.25X), cucumbers (uncooked cured, 0.2X), peach 

(cooked, 0.02X), peach (dried cooked, 0.14X), peach (juice, babyfood, 0.02X), peanut 

oil (prune, 0.5X), plum (prune, 0.33X), soybean oil (0.04X), squash (0.001X), tomato 

juice (0.25X), and tomato paste/puree (0.02X). All other processing factors were 

DEEMTM Ver. 7.87 default values. All consumption data for these assessments was 

taken from the USDA’s Continuing Survey of Food Intake by individuals (CSFII) 

with the 1994-96 consumption database and the Supplemental CSFII children’s 

survey (1998) consumption database. These assessments included all current and 

pending uses plus a proposed new IR 4 pre plant dip and foliar combination use on 

strawberries. Residue data for current and pending registrations were obtained 

from a number of sources including field trial data and monitoring data from the 

Pesticide Data Program (PDP), FoodContam (FC), and the FDA monitoring 

program. The current tolerance definition expression for chlorothalonil includes 

chlorothalonil plus the metabolite SDS3701. Since residue values for chlorothalonil 

in the PDP and other monitoring databases may not include residues of the 

SDS3701 metabolite, samples that had detectable residues of chlorothalonil were 

conservatively assigned a value of 10% of the reported chlorothalonil residue for an 

assumed residue of SDS3701, based upon the maximum ratio of metabolite SDS3701 

to chlorothalonil in radio-labeled plant studies (6.5%). A proposed tolerance of 0.02 

ppm was used for the proposed use on strawberries. Percent of crop treated values 
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were estimated based upon economic, pest and competitive pressures. Tolerancelevel residues were assumed for all meat commodities. For milk and milk derived 

commodities, relevant PDP monitoring database residue values were used. 

i. Food.

[Acute dietary (food only) assessments were not performed, since an endpoint of 

concern attributable to a single oral dose has not been identified.

Food Chronic Exposure: The chlorothalonil chronic dietary (food only) risk 

assessment was performed for all population subgroups using a chronic reference 

dose of 0.02 mg/kg-bw/day, based upon a NOAEL of 2.0 mg/kg-bw/day from a 

chronic rat toxicity study and an uncertainty factor of 100X for intra- and interspecies variability; no additional FQPA safety factor was applied. For the purpose 

of the aggregate risk assessment, exposure values were expressed in terms of margin 

of exposure (MOE), calculated by dividing the 2.0 mg/kg-bw/day endpoint by the 

exposure for each population subgroup. In addition, exposures were expressed as a 

percent of the chronic reference dose (%cRfD). Chronic dietary (food only) 

exposure to the U.S. population resulted in a MOE of 10,033 (1.0% of the cRfD). 

The most sensitive sub-population was children 1-2 years old, with a MOE of 6,178 

(1.6% of the cRfD). Since the Benchmark MOE for this assessment was 100 and 

since EPA generally has no concern for exposures above the benchmark or below 

100% of the reference dose, Syngenta believes that there is a reasonable certainty 

that no harm will result from dietary (food) exposure to residues arising from all 

current, pending, and proposed uses of chlorothalonil.

Cancer. Chlorothalonil is listed as “likely” to be a human carcinogen by all routes 

of exposure, however the SAP decision of 6/30/98 supports the use of a MOE 

approach. The HASPOC deliberated on 3/12/08 and supported the MOE approach.

ii. Drinking water. [Estimated Drinking Water Concentrations (EDWCs) 

for chlorothalonil TTR were calculated for the currently registered uses and the 

proposed uses on strawberries and citrus using the Tier II Model PE5, PRZM 

(Pesticide Root Zone Model) / EXAMS (Exposure Analysis Modeling Systems), to 

provide surface water exposure estimates and the Tier 1 Model, SCI-GROW 

(Screening Concentration In GROund Water), to provide ground water exposure 

estimates. For surface water, the currently registered Bravo Weather Stik® use on 

tomatoes was the driving crop use and provided the highest EDWCs, exceeding the 

proposed new IR-4 crop uses for strawberries and citrus. The use parameters for 

chlorothalonil on tomatoes consisted of seven aerial applications of 2.1 lbs 

chlorothalonil / A, and this use was modeled using the PRZM Crop Scenarios: CA, 

FL and PA Tomatoes. PRZM/EXAMS modeling provided an annual average 

(chronic) surface water EDWC of 72.9 ppb. For ground water the currently 

registered use, Daconil Ultrex® on golf course turf (greens), was the driving crop 

use and provided higher EDWCs than the proposed uses for strawberries and 

citrus. The application parameters for Daconil Ultrex® consisted of ten ground 

applications of 7.3 lbs. ai / A which provided an EDWC (acute and chronic) of 6.8 
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ppb for chlorothalonil TTR. Since the surface water EDWC exceeds the ground

water EDWC, the surface water value should be used for comparison purposes and 

is considered protective for any ground water concentration concerns. 

Acute Exposure from Drinking Water: Acute drinking water assessments were not 

performed, since an endpoint of concern attributable to a single oral dose has not 

been identified.

Chronic Exposure from Drinking Water: The chronic EDWC of 72.9 ppb (0.0729 

ppm) was used to calculate the chronic drinking water exposure values for the U.S. 

Population and all population subgroups. Chronic drinking water exposures to the 

U.S. Population resulted in a MOE of 1,302 (7.7% of the cRfD). The most sensitive 

sub-population was all infants <1 year, with a MOE of 397 (25.2% of the cRfD). 

Since the Benchmark MOE for this assessment was 100 and since EPA generally has 

no concern for exposures above the benchmark or below 100% of the reference 

dose, Syngenta believes that there is a reasonable certainty that no harm will result 

from dietary (food) exposure to residues arising from all current, pending, and 

proposed uses of chlorothalonil.

2. Non-dietary exposure. Chlorothalonil is a broad spectrum fungicide that 

can be applied to ornamentals and non-residential turfgrass and can also be 

formulated into paints for interior and exterior applications. There is a potential 

for residential exposure to adult handlers making applications to ornamentals 

and/or from using treated paint. There is also a potential for residential exposure to 

children from ingestion of paint chips containing chlorothalonil, although ingestion 

of paint chips is considered to be episodic in nature and is generally not included in 

aggregate risk so it was therefore excluded from these assessments as well. The 

chlorothalonil non-dietary risk assessment was performed using a short-term 

incidental oral and inhalation endpoint of 3.0 mg/kg-bw/day, based upon a NOAEL 

from a 90 day rat study in the rat and an uncertainty factor of 100X for intra- and 

inter-species variability; no additional FQPA safety factor was applied. For the 

purpose of the aggregate risk assessment, exposure values were expressed in terms 

of margin of exposure (MOE), calculated by dividing the 3.0 mg/kg-bw/day 

endpoint by the exposure for each population subgroup. The most exposed 

population subgroups from the non-dietary (residential) assessments was for male 

adults and youths (13 years and older) attributable to short-term inhalation 

exposures resulting from applying alkyd exterior paint with an airless sprayer, with 

a MOE of 147. Since the benchmark MOE for this assessment was 100 and since 

EPA generally has no concern for non-dietary exposures above the benchmark 

MOE, Syngenta believes that there is a reasonable certainty that no harm will result 

from non-dietary exposures from all current residential uses for chlorothalonil.

D. Cumulative Effects

Cumulative Exposure to Substances with a Common Mechanism of Toxicity. 

Section 408(b)(2)(D)(v) requires that, when considering whether to establish, 
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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”. Syngenta did not perform 

a cumulative risk assessment as part of this tolerance action for chlorothalonil 

because HED has not yet determined that there are any other chemical substances 

that have a mechanism of toxicity common with that of chlorothalonil. For 

purposes of this tolerance action, EPA has assumed that chlorothalonil does not 

have a common mechanism of toxicity with any other substance(s).

E. Safety Determination

1. U.S. population. The chronic aggregate exposure analysis (food plus water 

exposures) showed that exposure from all established and proposed uses of 

chlorothalonil resulted in a chronic MOE of 1,152 (8.7% of the cRfD) which exceeds 

the benchmark MOE of 100. The short-term aggregate exposure analysis (food plus 

water plus non-dietary residential exposures) showed that exposure from all 

established and proposed uses of chlorothalonil resulted in a MOE of 136 for adults 

50 years and older, which exceeds the benchmark MOE of 100. Based on the 

completeness and reliability of the toxicity data supporting these petitions, Syngenta 

believes that there is a reasonable certainty that no harm will result to the U. S. 

population from aggregate exposures arising from all current, pending, and 

proposed uses for chlorothalonil.

2. Infants and children. The chronic aggregate exposure analysis (food plus 

water exposures) showed that exposure from all established and proposed uses of 

chlorothalonil resulted in a MOE of 390 (25.6% of the cRfD) for all infants <1 year 

old, which exceeds the benchmark MOE of 100. The short-term aggregate exposure 

analysis (food plus water plus non-dietary residential exposures) showed that 

exposure from all established and proposed uses of chlorothalonil resulted in a 

MOE of 585 for infants <1 year old, which exceeds the benchmark MOE of 100. 

Based on the completeness and reliability of the toxicity data supporting these 

petitions, Syngenta believes that there is a reasonable certainty that no harm will 

result to infants and children from aggregate exposures arising from all current, 

pending, and proposed uses for chlorothalonil.

F. International Tolerances

Maximum Residue Levels (MRLs) for chlorothalonil have been established in a 

number of countries including Argentina, Australia, Brazil, Canada, Chile, China, 

France, Germany, Italy, Russia, and Spain. Compatibility between U.S. tolerances 

and Codex MRLs exist for beans/peas/dry beans, broccoli, brussel sprouts, carrots, 

celery, cherries, cranberries, cucumbers, melons, onions, peaches, squash, and 

tomatoes. Some incompatibilities exist between Codex MRLs and U.S. tolerances 

for bananas, cabbage, cauliflower, peanuts, and sweet corn. No questions of 

compatibility exist with respect to commodities where no Codex MRLs have been 

established but U.S. tolerances exist, or where Codex MRLs have been established 

but U.S. tolerances do not exist.
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