EPA REGISTRATION DIVISION COMPANY NOTICE OF FILING FOR PESTICIDE PETITIONS 

PUBLISHED IN THE FEDERAL REGISTER

EPA Registration Division contact: Erin Malone, 703-347-0253

 

Syngenta Crop Protection LLC. PP#2F8135

EPA has received a pesticide petition PP#2F8135 from Syngenta Crop Protection LLC., 

P.O. Box 18300, Greensboro, NC 27419-8300 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 180.434.

1. by establishing tolerance for residue of Propiconazole, 1-[[2-(2,4-

dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl] methyl]-1H-1,2,4-triazole and its 

metabolites determined as 2,4,-dichlorobenzoic acid and expressed as parent 

compound in or on the raw agricultural commodity Rapeseed subgroup 20A at

0.3 parts per million (ppm).

EPA has determined that the petition contains data or information regarding the 

elements set forth in section 408 (d)(2) of the 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. Syngenta conducted complete magnitude of residue trials on 

canola in Canada to support the requested use of propiconaozle. These residue trials 

satisfy the requested tolerance on rapeseed. 

1. Plant metabolism. The metabolism of propiconazole as well as the nature of 

the residues is adequately understood for purposes of the tolerances. Plant 

metabolism has been evaluated in five diverse crops, wheat, grapes, celery, peanuts 

and carrots which should serve to define the similar metabolism of propiconazole in a 
wide range of crops. The plant metabolism pathway for propiconazole is well 

understood. Parent metabolite CGA-64250 is the major compound found in crops. 

Comparison of the metabolism of propiconazole in different plant species shows that 

the differences between the respective metabolic pathways to be quantitative in 

nature.

2. Analytical method. The metabolism data in plants and animals suggest that 

analytical methods to detect either the phenyl or the triazole ring would be 

appropriate for the measurement of residues. However, because of the natural 

occurrence of compounds that interfere with the measurement of triazoles, methods 

designed to detect this moiety have been proven unreliable and unacceptable. 

Conversely, conversion of phenyl moiety to 2,4-dichlorobenzoic acid (DCBA) has 

proven to be satisfactory for all agricultural products analyzed to date. Analytical 

methods AG-626 and AG-454A were developed for the determination of residues of 

propiconazole and its metabolites containing the DCBA moiety. Analytical method 

AG-626 has been accepted and published by EPA as the tolerance enforcement 

method for crops. The limit of quantitation (LOQ) for the method is 0.05 ppm].

3. Magnitude of residues. . [IR-4 conducted magnitude of residue trials on 

several crops under OPPTS 860.1500 to support the requested use of propiconaozle 

in/on rapeseed subgroup 20A. The maximum residue of propiconaozle on canola was 

0.22 ppm. These residue trials satisfy the proposed tolerances for these crops. ]

B. Toxicological Profile

1. Acute toxicity. Propiconazole exhibits low toxicity. Data indicated the 

following: a rat acute oral LD50 of 1,517 milligrams/kilograms (mg/kg); a rabbit acute 

dermal LD50 >6,000 mg/kg; a rat inhalation LC50 >5.8 mg/liter air; minimal skin and 

slight eye irritation; and nonsensitization.

2. Genotoxicty. Propiconazole exhibits low toxicity. Data indicated the 

following: a rat acute oral LD50 of 1,517 milligrams/kilograms (mg/kg); a rabbit acute 

dermal LD50 >6,000 mg/kg; a rat inhalation LC50 >5.8 mg/liter air; minimal skin and 

slight eye irritation; and nonsensitization.

3. Reproductive and developmental toxicity. In an oral teratology study in the 

rabbit, a maternal no observed adverse effect level (NOAEL) of 30 mg/kg was based on 

reduced food intake but without any fetotoxicity even at the top dose of 180 mg/kg. 

In an oral teratology study in the rabbit, a maternal NOAEL of 100 mg/kg was based on 
reductions in body weight gain and food consumption and a fetal NOAEL of 250 mg/kg 

was based on increased skeletal variations at 400 mg/kg. In an oral teratology study 

in the rat, a maternal and fetal NOAEL of 100 mg/kg was based on decreased survival, 

body weight gain, and food consumption in the dams and delayed ossification in the 

fetuses at 300 mg/kg. In a second teratology study in the rat, a maternal and fetal 

NOAEL of 30 mg/kg was based on reductions in body weight gain and food 

consumption in the dams and delayed development in the fetuses at 90 and 360/300 

mg/kg. A supplemental teratology study in the rat involving eight times as many 

animals per group as usually required showed no teratogenic potential for the 

compound. A 2-generation reproduction study in the rat showed excessive toxicity at 

5,000 ppm without any teratogenic effects. A 2-generation reproduction study in the 

rat showed no effects on reproductive or fetal parameters at any dose level. 

Postnatal growth and survival were affected at the top dose of 2,500 ppm, and 

parental toxicity was also evident. The NOAEL for development toxicity is 500 ppm.

4. Subchronic toxicity. In a 21-day dermal study in the rabbit, a NOAEL of 200 

mg/kg was based on clinical signs of systemic toxicity. In a 28-day oral toxicity study 

in the rat, a NOAEL of 50 mg/kg was based on increased liver weight. In a subchronic 

feeding study in the mouse, a NOAEL of 20 ppm (3 mg/kg) was based on liver 

pathologic changes. In a 13 week feeding study in the male mouse, a NOAEL of 20 ppm 

(3 mg/kg) was based on liver pathologic changes. In a 90 day feeding study in rats, the 

NOAEL was 240 ppm (24 mg/kg) based on a reduction in body weight gain. In a 90 day 

feeding study in dogs, the NOAEL was 250 ppm (6.25 mg/kg) based on reduced food 

intake and stomach histologic changes.]

5. Chronic toxicity. In a 12-month feeding study in the dog, a NOAEL of 50 ppm 

(1.25 mg/kg) was based on stomach histologic changes. In a 24 month oncogenicity 

feeding study in the mouse, the NOAEL was 100 ppm (15 mg/kg). The MTD was 

exceeded at 2,500 ppm in males based on decreased survival and body weight. 

Increased incidence of liver tumor was seen in these males but no evidence of 

carcinogenicity was seen at the next lower dose of 500 ppm in either sex. In a 24 

month chronic feeding/oncogenicity study in the rat, a NOAEL of 100 ppm (5 mg/kg) 

was based on body weight and blood chemistry. The MTD was 2,500 ppm based on 

reduction in body weight gain and no evidence of oncogenicity was seen. Based on 

the available chronic toxicity data, Syngenta believes the Reference dose (RfD) for 

propiconazole is 0.0125 mg/kg/day. This RfD is based on a 1 year feeding study in 

dogs with a NOAEL of 1.25 mg/kg/day (50 ppm) and an uncertainly factor of 100. No 

additional modifying factor for the nature of effects was judged to be necessary as 

stomach mucous hyperemia was the most sensitive indicator of toxicity in that study.
Using the Guidelines for Carcinogenic Risk Assessment published on September 24, 

1986 (51 FR 33992), the USEPA has classified propiconazole in group C for 

carcinogenicity (evidence of possible carcinogenicity for humans). The compound was 

tested in 24 month studies with both rats and mice. The only evidence of 

carcinogenicity was an increase in liver tumor incidence in male mice at a dose level 

that exceeded the maximum tolerated dose (MTD). Dosage levels in the rat study 

were appropriate for identifying a cancer risk. The Cancer Peer Review Committee 

recommended the RfD approach for quantitation of human risk. Therefore, the RfD is 

deemed protective of all chronic human health effects, including cancer.] 

6. Animal metabolism. Metabolism in animals is similar to plant metabolism. In 

animals both the rat and the goat rapidly metabolize and excrete propiconazole. 

Neither animal retains significant amounts of propiconazole or its metabolites in 

tissues. Significant quantities of parent or metabolites do not appear in goat’s milk. 

Similar metabolites are produced by both species, and unconjugated (phase I) 

metabolites are similar in plants and animals.

The metabolism profile supports the use of an analytical enforcement method that 

accounts for combined residues of propiconazole and its metabolites that contain the 

2,4-dichlorobenzoic acid (DCBA) moiety.

7. Metabolite toxicology. There are no metabolites of concerned based on a 

differential metabolism between plants and animals.

8. Endocrine disruption. Developmental toxicity studies in rats and rabbits and 

reproduction studies in rats gave no indication that propiconazole 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. Further, due to the moderate rate of degradation of the 

product, there is no risk that propiconazole may accumulate in the environment. In 

animals, propiconazole is quickly excreted and has no tendency for accumulation in 

the body. Based on these results, it is very likely that propiconazole has no potential 

to interfere specifically with the endocrine system.

C. Aggregate Exposure

1. Dietary exposure. Tier I acute, short-term, and chronic aggregate exposure assessments 

were performed for propiconazole using the Dietary Exposure Evaluation Model software with 

the Food Commodity Intake Database (DEEM-FCIDTM, version 2.16) from Exponent. 

Propiconazole is currently registered for use on alfalfa (indirect), avocado (Section 18), 
bananas, barley, berries (Crop Groups 13-07A, 13-07B, and 13-07G), carrots, cilantro, corn 

(field, sweet, and popcorn), cranberries (regional), garden beets, grasses, leaf petioles (Crop 

Subgroup 4B), mushrooms, nectarines and peaches (Section 18, expires 31-Dec-2013), oats, 

onions (bulb and green), parsley, peanuts, peppermint, pineapples (seed piece treatment), 

pistachios, rice, rye, sorghum, soybeans, spearmint, stone fruits (Crop Group 12), 

strawberries, sugar beets, tree nuts (Crop Group 14), wheat, wild rice (regional), and turf and 

ornamental uses, a revised use on mint (7-day PHI), revised use patterns for Propi-ShieldTM 

brand paint and stain additive products, IR-4 foliar uses on succulent and dried legumes (Crop 

Group 6), post-harvest uses on citrus fruit (Crop Group 10-10), stone fruit (Crop Group 12), and 

tomatoes (Crop subgroup 8–10A). Pending uses include a foliar use on sugarcane and foliar 

use on small cereal grains including barley, oats, rye, and wheat. Existing (40CFR180.434) or 

estimated tolerances were used for all commodities. DEEMTM (version 7.87) default processing 

factors were used for all processed commodities except citrus oil (185X), orange juice 

(0.011X), pineapple juice (0.11X), pineapple process residue (1.49X), sugarcane sugar (0.02X), 

and sugarcane molasses (0.49X). No adjustments were made for “percent crop treated,” i.e., 

100%CT was assumed. For livestock commodities, established tolerances were used where 

available for beef and dairy, however for livestock commodities that do not already have 

established tolerances (i.e., pork meat, fat, and all poultry commodities), anticipated residues 

were calculated by constructing theoretical “maximum reasonably balanced diet” (MRBD) 

livestock diets. Drinking water estimates were selected using the higher of the estimated 

drinking water concentrations (EDWCs) for surface and ground water. All consumption data 

for these assessments were taken from the USDA’s Continuing Survey of Food Intake by 

individuals (CSFII) with the 1994-1996 consumption database and the Supplemental CSFII 

children’s survey (1998) consumption database. 

i. Food

Acute Food Risk: The acute dietary (food only) risk assessment was performed for all 

population subgroups with an acute reference dose (aRfD) of 0.3 mg/kg-bw/day based on an 

acute no observed adverse effect level (NOAEL) of 30 mg/kg-bw/day from an acute 

neurotoxicity study in rats and an uncertainly factor of 100X. The 100X safety factor included 

intra- and inter-species variations. No additional FQPA safety factor was applied. For the 

purpose of the aggregate risk assessment, the exposure value was expressed in terms of 

margin of exposure (MOE), which was calculated by dividing the NOAEL by the exposure for 

each sub-population. In addition, exposure was expressed as a percent of the acute reference 

dose (%aRfD). At the 95th percentile, acute exposure to the U.S. population resulted in a MOE 

of 667 or 15.0% of the aRfD (Benchmark = 100; aRfD = 0.3 mg/kg-bw/day). Acute exposure to 

the most sensitive subpopulation (children 1-2 years old) resulted in a MOE of 277 or 36.0% of 

the aRfD (Benchmark = 100; aRfD = 0.3 mg/kg-bw/day). Since the Benchmark MOE for this 

assessment is 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 acute dietary (food) exposure to residues arising from all 

current, pending, and proposed uses for propiconazole.

Chronic Food Risk: The chronic dietary (food only) risk assessment was performed for 

all population subgroups with a chronic reference dose (cRfD) of 0.1 mg/kg-bw/day 

based on a 24-month oncogenicity study in mice with a NOAEL of 10 mg/kg-bw/day 

and an uncertainly factor of 100X. The 100X safety factor included intra- and 

interspecies variations. No additional FQPA safety factor was applied. For the 

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

terms of margin of exposure (MOE), which was calculated by dividing the NOAEL by 

the exposure for each sub-population. In addition, exposure was expressed as a 

percent of the chronic reference dose (%cRfD). Chronic exposure to the U.S. 

population resulted in a MOE of 720 or 13.9% of the cRfD (Benchmark = 100; cRfD = 

0.1 mg/kg-bw/day). Chronic exposure to the most exposed sub-population (children 

1-2 years old) resulted in a MOE of 273 or 36.6% of the cRfD (Benchmark = 100; cRfD = 

0.1 mg/kg-bw/day). Since the Benchmark MOE for this assessment is 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 chronic dietary (food) exposure to residues arising from all 

current, pending, and proposed uses for propiconazole. 

Cancer Risk: A quantitative risk assessment using a cancer endpoint was not 

performed. The chronic risk assessment is adequately protective for cancer risk as 

well as other chronic effects.

ii. Drinking Water. The Estimated Drinking Water Concentrations (EDWCs) of 

propiconazole were determined using Tier l SCI-GROW (version 2.3) which estimates 

pesticide concentration in ground water and Tier II PRZM/EXAMS (PE version 5.0) 

which estimates pesticide concentration in surface water. This drinking water 

assessment was conducted to assess all currently registered uses, the pending change 

to the use pattern for mint, and the proposed use on legume vegetables (succulent 

and dried) as well as proposed post-harvest uses on citrus, stone fruit, and tomatoes. 

The post-harvest uses have no impact on drinking water because post-harvest 

treatment is an indoor use posing negligible impact to drinking water concentrations. 

For groundwater, the currently registered use on turf provided the highest EDWC of 

0.725 ppb (acute and chronic). For surface water, the currently registered use on turf 

provided an acute EDWC of 101.826 ppb and a chronic EDWC of 52.438 ppb. No 

Percent Cropped Area (PCA) adjustments were made for surface water EDWCs. Since 

the surface water EDWCs exceed the ground water EDWC, the surface water values 
were used for risk assessment purposes and will be considered protective for any 

ground water exposure concerns. 

Acute Exposure from Drinking Water. The acute surface water EDWC of 101.826 ppb 

was input directly into the DEEM-FCIDTM software as “water, direct and indirect, all 

sources” to model the acute drinking water exposures. Exposure contributions at the 

95%-ile of exposures were determined by taking the difference between the aggregate 

(food + drinking water) exposures and the food (alone) exposures for each subpopulation. Acute drinking water exposure U.S. population resulted in a MOE of 3,467 

(0.9% of the aRfD of 0.30 mg/kg-bw/day). The most exposed sub-population was 

children 1-2 years old, with a MOE of 2,227 (1.3% of the aRfD of 0.30 mg/kg/day). 

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 aRfD, Syngenta 

believes that there is a reasonable certainty that no harm will result from acute 

drinking water exposure to residues arising from all current, pending, and proposed 

uses for propiconazole.

Chronic Exposure from Drinking Water. The chronic surface water EDWC of 52.438 ppb was 

input directly into the DEEM-FCIDTM software as “water, direct and indirect, all sources” to 

model the chronic drinking water exposures. Chronic drinking water exposure to the U.S. 

population resulted in a MOE of 9,048 (1.1% of the cRfD of 0.10 mg/kg-bw/day). The most 

exposed sub-population was infants <1 year old, with a MOE of 2,760 (3.6% of the cRfD of 0.10 

mg/kg-bw/day). 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 cRfD, 

Syngenta believes that there is a reasonable certainty that no harm will result from chronic 

drinking water exposure to residues arising from the current, pending, and proposed uses for 

propiconazole.

2. Non-dietary exposure. Short-term exposure assessments were conducted to 

assess exposures resulting from non-dietary uses of propiconazole arising from 

registered turf and ornamental uses and from Propi-ShieldTM brand paint and stain 

additive products containing propiconazole. Adult turf and ornamental handler 

scenarios assessed included low-pressure hand wand sprayer, garden hose-end 

sprayer, granular push spreader, hand held belly grinder spreader, and spreading 

granular formulation by hand. Adult and youth post-application exposure scenarios 

included high contact activities (lawns) and golf. For children, re-entry to treated 

turfgrass areas resulted in dermal and non-dietary oral exposures via hand-to-mouth, 

object-to-mouth, and ingestion of treated soil. A dermal absorption value of 40% was 

used to calculate exposure for turf and ornamental uses. For Propi-ShieldTM brand 

paint additive products, adult applicator scenarios assessed included paintbrush and 

roller applications of in-can treated paint and stain, airless sprayer application of in-
can treated paint and stain, and low-pressure hand wand sprayer application of wood 

preservative stains. Dermal absorption values of 1.0% and 26.6% for consumers 

applying paint or stain, respectively, were taken from a recent EPA assessment (DP# 

D364956, Nov. 2009). For all turf and ornamental scenarios assessed, the worst-case 

combined short-term MOE was 181 (Benchmark = 100) for children 1-6 years old for 

combined dermal and non-dietary oral exposures resulting from post-application 

exposures to propiconazole treated turfgrass. Post-application exposure to 

ornamental plants is negligible; and was, therefore, not assessed. For all paint and 

stain scenarios assessed, the worst-case combined short-term MOE was 160 

(Benchmark = 100) for all adults 20+ years old applying in-can treated stain with an 

airless sprayer. Exposure risks were also assessed for children’s accidental ingestion 

of lawn granules (MOE = 331) and paint chips (MOE = 4,500) containing propiconazole 

and were found to be acceptable (Benchmark MOE = 100); the ingestion of lawn 

granules and paint chips by children is considered to be episodic in nature and is not 

aggregated with dietary or other residential exposures. Since the Benchmark MOE for 

this assessment was 100 and since the EPA generally has no concern for exposures 

above the benchmark, Syngenta believes that there is a reasonable certainty that no 

harm will result from short-term non-dietary exposures arising from all current,

pending, and proposed uses for propiconazole.

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, 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”. Propiconazole is a member of the triazolecontaining class of pesticides. Although conazoles act similarly in plants (fungi) by 

inhibiting ergosterol biosynthesis, there is not necessarily a relationship between this 

pesticidal activity and their mechanism of toxicity in mammals. Structural similarities 

do not constitute a common mechanism of toxicity. There is currently no evidence to 

indicate that conazoles share common mechanisms of toxicity and the EPA is not 

following a cumulative risk approach based on a common mechanism of toxicity for 

the conazoles.

E. Safety Determination

1. U.S. population. Using the conservative assumptions described above, and 

based on the completeness and reliability of the toxicity data, the acute aggregate 

(food plus water) exposure calculation for all current, pending, and proposed uses of 

propiconazole provided a MOE of 621 for the U.S. population. For short-term 

exposures, chronic dietary (food and water) exposures were aggregated with 

residential exposures, resulting in a worst-case short-term aggregate MOE of 148 for 
the U.S. population. The chronic aggregate exposure analysis (food and water) 

showed that exposures from all current, pending, and proposed propiconazole uses 

resulted in a MOE of 649 for the U.S. population. Since the worst case aggregate MOE 

of 148 (short-term risk) exceeds the Benchmark MOE of 100, Syngenta believes that 

there is a reasonable certainty that no harm will occur to the U.S. population from 

aggregate exposures arising from all current, pending, and proposed uses for 

propiconazole.

2. Infants and children. Using the conservative assumptions described above, 

and based on the completeness and reliability of the toxicity data, the acute aggregate 

(food plus water) exposure calculation for all current, pending, and proposed uses of 

propiconazole provided a MOE of 267 for children 1-2 years old. For short-term 

exposures, chronic dietary (food and water) exposures were aggregated with 

residential exposures resulting in a short-term aggregate MOE of 150 for children 1-6 

years old. The chronic aggregate exposure analysis (food and water) showed that 

exposures from all current, pending, and proposed propiconazole uses resulted in a 

MOE of 262 for children 1-2 years old. Since the worst case aggregate MOE of 150 

(short-term risk) exceeds the Benchmark MOE of 100, Syngenta believes that there is a 

reasonable certainty that no harm will occur to infants and children from aggregate 

exposures arising from all current, pending, and proposed uses for propiconazole.

F. International Tolerances

The Codex Alimentarius Commission has established several maximum residue 

limits (MRLs) for propiconazole in or on various raw agricultural commodities. The 

Codex MRLs are expressed in terms of propiconazole per se. In addition, both Canada 

and Mexico have established MRLs/tolerances on several commodities which also 

have U.S. tolerances. The U.S. tolerance expression includes all metabolites 

determined as 2,4-dichloro-benzoic acid. In conjunction with the reregistration 

process EPA intends to revise the tolerance expression to propiconazole per se. To the 

extent possible, for the present petitions, U.S. tolerances have been numerically 

harmonized with Codex, Canadian and Mexican MRLs; however, differences in use 

patterns and the supporting residue data have precluded reducing many tolerances. A 

summary of Codex MRLs, Canadian MRLs and Mexican tolerances and the 

corresponding U.S. tolerances for propiconazole is discusses at www.regulations.gov

Docket No. EPA-HQ-OPP-2006-0347-0004; pages 53-54