EPA REGISTRATION DIVISION - COMPANY NOTICE OF FILING

FOR PESTICIDE PETITION

 Docket ID Number: EPA-HQ-OPP-2012-0586

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

Interregional Research Project Number 4 

Pesticide Petition Number (PP #): 2E8050

EPA has received a pesticide petition (PP#: 2E8050) from Interregional Research

Project Number 4 (IR-4), IR-4 Project Headquarters, Rutgers, The State University of New

Jersey, 500 College Road East, Suite 201 W, Princeton, NJ 08450 requesting, 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 by establishing a tolerance for residues of halosulfuron-methyl,

methyl 3-chloro-5- [[[[(4,6-dimethoxy-2 pyrimidinyl)amino] carbonyl]amino]sulfonyl]-1-

methyl-1 H- pyrazole-4-carboxylate, and its metabolites and degradates in or on the raw

agricultural commodities canberry and artichokes. 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 support granting of the petition. Additional data may be needed

before EPA rules on the petition.

A. Residue Chemistry

1. Plant metabolism. The metabolism of halosulfuron-methyl as well as the nature of 

the residues in plants is adequately understood for the purposes of these tolerances. 

Metabolism studies were conducted with three crops, vis.; field com, sugarcane and soybeans. 

Metabolism depends on the mode of application. Pre-emergent applications result in rapid

soil degradation of halosulfuron-methyl followed by crop uptake of the resulting pyrazole

moiety. The pyrimidine ring binds tightly to soil and is eventually converted to carbon

dioxide by microbial degradation. In post-emergent applications, little metabolism and

translocation take place, resulting in unmetabolized parent compound as the major residue on

the directly treated foliar surfaces.

2. Analytical method. A practical analytical method, gas chromatography with a 

nitrogen-specific detector, is available for enforcement purposes. The analytical method

accounts for parent halosulfuron-methyl and for the halosulfuron-methyl rearrangement 

ester, sometimes referred to as "RRE" and "MON 5781." This product results from the 

abstraction for the S02NHCO moiety between the rings, such that the two rings are then 

joined together only by an NH group. In caneberries, the limit of detection and limit of 

quantification was 0.016 ppm and 0.047 ppm, respectively. The limit of detection in 

artichokes was 0.0126 ppm and the limit of quantification was 0.0387 ppm.
3. Magnitude of residues. Studies were conducted to determine the residues of 

halosulfuron in caneberry in EPA Regions 1, 2,5,10, and 12 as well as PMRA region SA. 

Caneberry rows were treated with 0.094 lbs halosulfuron-methyl a.i./A and berries were 

collected 13-15 days after application. The maximum residue of halosulfuron-methyl was 

below the limit of detection (LOD) of 0.016 ppm.

Artichokes studies were conducted in Region 10. Treated plots received one 

halosulfuron-methyl application directed onto ditches and bed shoulder 5 days prior to 

harvest at the rate of .094 lb halosulfuron-methyl a.i./A. The maximum residue of 

halosulfuron-methyl in artichokes buds was below the limit of quantification (LOQ) of

0.0378 ppm.

B. Toxicological Profile

1. Acute toxicity. Halosulfuron-methyl has low acute toxicity via the oral, 

dermal, and inhalation routes. It is a non-irritant for skin and eyes and is not a dermal 

sensitizer.

2. Genotoxicty. Carcinogenicity studies in rats and mice show no increase in 

treatment-related tumor incidence, and halosulfuron-methyl was classified as "not likely to

be carcinogenic to humans." Halosulfuron-methyl is negative for mutagenicity in a battery

of genotoxicity studies. Bacterial and mammalian microsomal mutagenicity assays

showed halosulfuron-methyl not to be mutagenic. Gene mutation and chromosomal

aberration studies were negative. An unscheduled DNA test in primary rat hepatocytes

was negative. An in vivo mouse micronucleus assay did not cause a significant increase in

the frequency of micronucleated polychromaticerythrocytes in bone marrow cells.

3. Reproductive and developmental toxicity. Although the halosulfuron 

methyl data indicated an increase in qualitative susceptibility in fetuses following

prenatal exposure in rats and rabbits, the developmental effects were seen in the presence

mg/kg/day in males and 147 mg/kg/day in females. The LOAEL was 497 mg/kg/day for

males and 640 mg/kg/day in females. Decreased body weight gain was observed in females

in the subchronic oral toxicity study. In the rat and mouse, there was a decrease in body

weight gains at high dose levels in short- and long-term oral and dermal studies. The results

of both acute and subchronic neurotoxicity studies showed no neurotoxic effects. There was

no quantitative evidence for increased susceptibility following pre- and/or post-natal

developmental effects.

4. Subchronic toxicity. A 90-day feeding study in rats resulted in a NOAEL of 116

mg/kg/day in males and 147 mg/kg/day in females. The LOAEL was 497 mg/kg/day for

males and 640 mg/kg/day in females. Decreased body weight gain was observed in females in 

the subchronic oral toxicity study. In the rat and mouse, there was a decrease in body weight 

gains at high dose levels in short- and long-term oral and dermal studies. The results of both 

acute and subchronic neurotoxicity studies showed no neurotoxic effects. There was no 

quantitative evidence for increased susceptibility following pre- and/or post-natal 

developmental effects. ·
5. Chronic toxicity. With repeated dosing, available data show that the dog is the 

most sensitive mammalian species. In the dog, decreased body weight was seen in the 

chronic oral toxicity study. Carcinogenicity studies in rats and mice show no increase in 

treatment-related tumor incidence, and halosulfuron-methyl was classified as "not likely to

be carcinogenic to humans."

6. Animal metabolism. The Agency has determined that the nature of the residue in

ruminants is adequately understood. In the tissues and milk of goats, the major extractable

residue was the unmetabolized parent compound. The Agency has not required tolerances

for residues in poultry. In the rat metabolism study, parent compound was absorbed

rapidly but incompletely. Excretion was relatively rapid at all doses tested, and the

majority of the radioactivity was eliminated in the urine and feces within 72 hours. Fecal

elimination was the result of unabsorbed parent compound.

7. Metabolite toxicology. Various toxicity studies have shown that the metabolite

3-CSA is of lower toxicity than the parent compound, and the Agency has concluded that 

it should not be included in the tolerance expression. However, in the residue analytical 

method for animal products, halosulfuron-methyl and all of its metabolites are

hydrolyzed to 3-CSA, which is analyzed and the results expressed as parent equivalents. 

The tolerance expression for plant commodities consists of only parent compound.

8. Endocrine disruption. No specific tests have been conducted with halosulfuronmethyl to determine whether the chemical may have an effect in humans that is similar to 

an effect produced by a naturally occurring estrogen, or other endocrine effects.

However, there were no significant findings in relevant toxicology studies; e.g., 

teratology and reproduction studies, which suggest that halosulfuron-methyl produces 

effects characteristic of the estrogen disruption. Halosulfuron is not on the initial EPA 

screening list and a test order has not been issued.

C. Aggregate Exposure

I. Dietary exposure. Tolerances have previously been established for residues in a 

variety of raw agricultural commodities (40 CFR 180.479). Additionally, tolerances have 

been established for halosulfuron-methyl and its metabolites in the meat byproducts of 

cattle, goats, hogs, horses and sheep.

i. Food. Chronic Dietary Exposure. A chronic dietary analysis for halosulfuronmethyl was conducted by the Agency using tolerance levels and 100% CT for all existing 

uses on April 5, 2010. The EDWC for surface water from EFED (59.2 ppb based on

modeled use on rice) was incorporated directly into the exposure analysis. The drinking

water estimate should be considered highly conservative. The results of the analysis 

indicate that chronic risk from the dietary exposure to halosulfuron-methyl does not exceed

HED's LOC for the general U.S. population or any population subgroup. The estimated

risk for the general U.S. population is 2% of the chronic PAD (cPAD), and the highest

exposure is to all infants (<1 year old) at 5% ofthe cPAD. The addition of residues in
caneberries and artichokes were at the LOD or LOQ and, therefore would not be expected

to contribute significantly to chronic dietary exposure.

Acute Dietary Exposure. An acute dietary exposure analysis for halosulfuron-methyl

was conducted using tolerance-level residues and 100 %crop treated (CT) for all existing

on April 5, 2010. Estimated drinking surface water concentrations (EDWCs) from EFED 

(59.2 ppb based on modeled use on rice) were incorporated directly into the exposure 

analysis. The only population with a toxicological endpoint attributable to a single dose of

halosulfuron-methyl was females 13-49 years old. The results of the analysis indicate that

acute risk from the dietary exposure to halosulfuron-methyl is less than 1% of the acute

population adjusted dose (aPAD) for females 13-49 years old, and therefore did not exceed

HED's LOC.

ii. Drinking water. Based on the First Index Reservoir Screening Tool (FIRST), 

Pesticide Root Zone Model I Exposure Analysis Modeling System (PRZM/ EXAMS)and 

Screening Concentration in Ground Water (SCI -GROW) models, the estimated drinking 

water concentrations (EDWCs) of halosulfuron methyl are Tier I EDWCs based on a 

maximum annual application rate of 0.125 lb active ingredient ai/A. The seasonal use 

proposed on caneberries and artichokes is 0.094 lb halosulfuron ai/A, well below the 

maximum annual rate used in the models derived for estimating drinking water 

concentrations. For acute and chronic dietary risk assessment, the water concentration 

value of 59.2 ppb was used to assess the contribution to drinking water.

2. Non-dietary exposure. Halosulfuron-methyl is registered for use on residential 

turfgrass and landscaped areas. The short-term aggregate risk assessment estimates risks 

that are likely to result from exposures up to 30 days. The same toxicological effect upon 

which endpoints were defined (decreased bodyweight gain) was observed across all

routes of exposure. The Agency's level of concern is a short-term aggregate (food, 

water and residential) MOE of less than 300. However, the Agency has previously 

calculated aggregate MOEs of 3,100 or greater. The proposed uses of halosulfuronmethyl on caneberries and artichokes should have negligible effect on the Agency's 

previous calculations.

D. Cumulative Effects

EPA has not made a common mechanism of toxicity finding regarding 

halosulfuron-methyl and any other substance. Halosulfuron-methyl does not appear to 

produce a toxic metabolite that is produced by any other substance. Therefore, for the

purposes of this tolerance action, EPA has not assumed that halosulfuron-methyl has a

common mechanism of toxicity with other substances.

E. Safety Determination

1. U.S. population. Chronic dietary (food and drinking water) exposure to 

halosulfuron methyl is below EPA's level of concern for the general U.S. population and 

all population subgroups. The Agency determined the chronic RID for halosulfuron 
methyl at 0.1 mg/kg/day for all populations based on the chronic dog study NOAEL at

10 mg/kg/day and I OOx uncertainty factor. The chronic dietary exposure estimates are

2% of the cPAD for the general U.S. population and 5% of the cPAD for all infants (<1 

year old), the most highly exposed population subgroup, much lower than the LOC at

100% of the cRtD.

2. Infants and children. In rat and rabbit developmental toxicity studies and a 2-

generation reproduction toxicity study in rats there was no quantitative evidence for 

increased susceptibility following pre-natal and/or post natal exposure. In those studies, 

NOAELs/ LOAELs for halosulfuron developmental and maternal toxicities, and 

developmental effects were seen in the presence of maternal toxicity, and the effects were 

only seen at the high dose. Additionally, in rats, developmental effects were seen at a

dose which is approaching the limit-dose. The degree of concern is low and there is no 

residual uncertainty for prenatal toxicity in both rats and rabbits.

F. International Tolerances

FFDCA §408(b)(4) requires the Agency to consider international standards in 

establishing a tolerance. There is no established Codex MRL specifically for artichokes 

however, a tolerance of 0.0 I ppm has been maintained for vegetable fresh or frozen. 

There is no Codex MRL for raspberries or blackberries 

http://www.mrldatabase.com/results.cfm - retrieved 2/7/20 I2).