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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460 

OFFICE OF PREVENTION, PESTICIDE

AND TOXIC SUBSTANCES

MEMORANDUM

Date: 15 October 2009

SUBJECT: Nicosulfuron – Dietary Exposure and Risk Analysis to Evaluate a New Use 

Request for Grasses.

PC Code: 129008 DP Barcode: D369742

MRID No.: NA Registration No.: 352-IRO

Petition No.: 8F7501 Regulatory Action: Section 3

Assessment Type: Dietary – Single Chemical Registration Case No.: NA

TXR No.: None CAS No.: 111991-09-4

Decision No.: 404568 40 CFR 180.454

FROM: Michael A. Doherty, Ph.D., Senior Chemist

Risk Assessment Branch II

Health Effects Division (7509P)

THROUGH: P. Yvonne Barnes, Biologist

Nancy Dodd, Chemist

Dietary Exposure Science Advisory Council

Richard A. Loranger, Ph.D., Senior Scientist

Risk Assessment Branch II

Health Effects Division (7509P)

TO: Michael A. Doherty, Ph.D., Senior Chemist

Risk Assessment Branch II

Health Effects Division (7509P)

Mindy Ondish/Jim Tompkins (RM 25)

Herbicide Branch

Registration Division (7505 P)

Executive Summary

A chronic combined dietary (food + drinking water) exposure and risk assessment was

conducted using the Dietary Exposure Evaluation Model DEEM-FCIDTM, Version 2.03 which 

uses food consumption data from the U.S. Department of Agriculture’s Continuing Surveys of 

Food Intakes by Individuals (CSFII) from 1994-1996 and 1998. The analysis was completed to 
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evaluate a requested use on grasses. Although the action does not affect any human foods 

directly, the use, if granted, will result in new tolerances for residues in meat and milk 

commodities.

No hazards associated with acute dietary exposure were identified for nicosulfuron; therefore, 

only a chronic evaluation was conducted. The analysis assumes tolerance-level residues and 

100% crop treated for all foods (corn, meat, and milk commodities). Even with these highly 

conservative assumptions, the resulting risk estimates are less than 1% of the chronic populationadjusted dose (cPAD) for all population subgroups. Generally HED is concerned when risk 

estimates exceed 100% of the cPAD. Nicosulfuron is not a carcinogen; therefore, there are no 

cancer concerns associated with this herbicide. There are no dietary exposure considerations that 

would preclude granting the requested use.

I. Introduction

Dietary risk assessment incorporates both exposure and toxicity of a given pesticide. For acute 

and chronic assessments, the risk is expressed as a percentage of a maximum acceptable dose 

(i.e., the dose which HED has concluded will result in no unreasonable adverse health effects). 

This dose is referred to as the population adjusted dose (PAD). The PAD is equivalent to point 

of departure (POD, NOAEL, LOAEL, e.g.) divided by the required uncertainty or safety factors.

For acute and non-cancer chronic exposures, HED is concerned when estimated dietary risk 

exceeds 100% of the PAD. HED is generally concerned when estimated cancer risk exceeds one 

in one million. References which discuss the acute and chronic risk assessments in more detail 

are available on the EPA/pesticides web site: “Available Information on Assessing Exposure 

from Pesticides, A User’s Guide,” 21-JUN-2000, web link: http://www.epa.gov/fedrgstr/EPAPEST/2000/July/Day-12/6061.pdf ; or see SOP 99.6 (20-AUG-1999).

The most recent dietary risk assessment for nicosulfuron was conducted by D. Hrdy (20 

November 2004, D302694).

II. Residue Information

Existing and recommended tolerance-level residues [40 CFR §180.454] have been used for all 

food commodities in this assessment. The existing tolerances are 0.1 ppm for all corn 

commodities. The recommended tolerances for livestock commodities (of cattle, horses, and 

sheep only) are 0.01 ppm for meat and fat, 0.05 ppm for meat byproducts, and 0.01 ppm for 

milk. A default processing factor of 1.5 from DEEM 7.78 was used for corn syrup, and it was 

assumed that 100% of foods in the assessment had residues of nicosulfuron (i.e., 100% crop 

treated). The inputs used in the assessment are provided in Attachment 1.

III. Drinking Water Data

The drinking water residues used in the dietary risk assessment were provided by the 

Environmental Fate and Effects Division (EFED) in the following memorandum: Tier 1 

Estimated Environmental Concentrations of Nicosulfuron, for Use in Human Health Risk 
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Assessment” by L. Liu (28 July 2004; D301842, D302623, D302624) and incorporated directly 

into this dietary assessment. Water residues were incorporated in the DEEM-FCID into the food 

categories “water, direct, all sources” and “water, indirect, all sources.” Estimates were derived 

based on the use on corn and are considered worst-case. The surface water estimate of 0.685 ppb 

(0.000685 ppm) is greater than the groundwater estimate (0.056 ppb) and was used in the 

assessment. The models (FIRST and SCIGROW) are conservative with respect to protecting 

human health. Both of the models and their full descriptions are available at the EPA internet 

site: http://www.epa.gov/oppefed1/models/water/.

IV. DEEM-FCIDTM Program and Consumption Information

The nicosulfuron chronic dietary exposure assessment was conducted using the Dietary

Exposure Evaluation Model software with the Food Commodity Intake Database DEEMFCIDTM, Version 2.03, which incorporates consumption data from USDA’s Continuing Surveys 

of Food Intakes by Individuals (CSFII), 1994-1996 and 1998. The 1994-96, 98 data are based on 

the reported consumption of more than 20,000 individuals over two non-consecutive survey

days. Foods “as consumed” (e.g., apple pie) are linked to EPA-defined food commodities (e.g. 

apples, peeled fruit - cooked; fresh or N/S; baked; or wheat flour - cooked; fresh or N/S, baked) 

using publicly available recipe translation files developed jointly by USDA/ARS and EPA. For 

chronic exposure assessment, consumption data are averaged for the entire U.S. population and 

within population subgroups, but for acute exposure assessment are retained as individual 

consumption events. Based on analysis of the 1994-96, 98 CSFII consumption data, which took 

into account dietary patterns and survey respondents, HED concluded that it is most appropriate 

to report risk for the following population subgroups: the general U.S. population, all infants (<1 

year old), children 1-2, children 3-5, children 6-12, youth 13-19, adults 20-49, females 13-49, 

and adults 50+ years old.

For chronic dietary exposure assessment, an estimate of the residue level in each food or foodform (e.g., orange or orange juice) on the food commodity residue list is multiplied by the 

average daily consumption estimate for that food/food form to produce a residue intake estimate. 

The resulting residue intake estimate for each food/food form is summed with the residue intake 

estimates for all other food/food forms on the commodity residue list to arrive at the total 

average estimated exposure. Exposure is expressed in mg/kg body weight/day and as a percent 

of the cPAD. This procedure is performed for each population subgroup.

V. Toxicological Information

The toxicological database for nicosulfuron is generally complete for purposes of human health 

risk assessment. New data are required to satisfy revised requirements [40 CFR Part 158]; 

nevertheless, HED does not believe that any additional safety factors are required to account for 

these data gaps given the available data and effects observed. The doses and endpoints for 

dietary risk assessment are summarized in Table 1.
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Table 1. Summary of Toxicological Doses and Endpoints for Nicosulfuron for Use in Dietary Human Health 

Risk Assessments

Exposure/

Scenario

Point of 

Departure

Uncertainty and 

FQPA Safety 

Factors

RfD & PAD, 

for Risk 

Assessment

Study and Toxicological Effects

Acute Dietary

(All populations)

An endpoint of concern attributable to a single dose was not identified.

Chronic Dietary 

(All Populations)

NOAEL=125

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 1x

Chronic RfD = 

cPAD = 

1.25mg/kg/day

Oral toxicity – dog

NOAEL = 125 mg/kg/day based upon

decreased body weight gain in males 

and the statistically significant increase 

in the relative liver and kidney weights 

of males at the LOAEL of 500 

mg/kg/day. Supported by the NOAEL 

of 100 mg/kg/day/LOAEL 500 

mg/kg/day in the rabbit developmental 

toxicity study.

Cancer (oral, 

dermal, inhalation)

Classification: “Not likely to be Carcinogenic to Humans” based on lack of tumorigenic 

effects in rodent (rats and mice) bioassays at the limit doses and lack of mutagenic effects in

the in vitro and in vivo genotoxicity assays.

Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and 

used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human 

exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = 

uncertainty factor. UFA = extrapolation from animal to human (interspecies). UFH = potential variation in 

sensitivity among members of the human population (intraspecies). FQPA SF = FQPA Safety Factor. PAD = 

population adjusted dose (a = acute, c = chronic). RfD = reference dose.

VI. Results/Discussion 

As stated above, for acute and chronic assessments, HED is concerned when dietary risk exceeds 

100% of the PAD. The DEEM-FCIDTM analyses estimate the dietary exposure of the U.S. 

population and various population subgroups. The results reported in Table 2 are for the general 

U.S. Population, all infants (<1 year old), children 1-2, children 3-5, children 6-12, youth 13-19, 

females 13-49, adults 20-49, and adults 50+ years. Cancer risk is determined for the general 

U.S. population only. All dietary risk estimates are less than 1% of the cPAD and, therefore, are 

not of concern.

Table 2. Summary of Dietary (Food + Drinking Water) Exposure and Risk for Nicosulfuron.

Population Subgroup

Acute (95th Percentile) Chronic Cancer

Exposure 

(mg/kg/day) % aPAD

Exposure

(mg/kg/day) % cPAD

Exposure

(mg/kg/day) Risk

General U.S. Population

N/A N/A

0.000300 <1

N/A N/A

All Infants (< 1 year old) 0.000454 <1

Children 1-2 years old 0.000835 <1

Children 3-5 years old 0.000766 <1

Children 6-12 years old 0.000540 <1

Youth 13-19 years old 0.000362 <1

Adults 20-49 years old 0.000225 <1

Adults 50+ years old 0.000151 <1

Females 13-49 years old 0.000226 <1

N/A = Not Applicable
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VII. Characterization of Inputs/Outputs

This assessment is a screening-level evaluation. The inputs and assumptions used in this 

assessment are highly conservative with respect to dietary exposure and the exposure estimates 

presented in Table 2 are likely to overestimate any actual dietary exposures to nicosulfuron. 

VIII. Conclusions

There are no dietary exposure considerations that would preclude establishing tolerances for 

residues of nicosulfuron or granting the requested uses.

IX. List of Attachments

Attachment 1. Summary of input values for the chronic dietary assessment of nicosulfuron.

Attachment 2. Results of the chronic dietary exposure and risk assessment for nicosulfuron.
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Attachment 1. Summary of input values for the chronic dietary assessment of nicosulfuron.

U.S. Environmental Protection Agency Ver. 2.00

DEEM-FCID Chronic analysis for NICOSULFURON 1994-98 data

Residue file: C:\Documents and Settings\mdoherty\My Documents\Chemistry 

Reviews\Nicosulfuron\129008 - 2009 Chronic.R98

 Adjust. #2 NOT used

Analysis Date 09-30-2009 Residue file dated: 09-30-2009/11:44:06/8

Reference dose (RfD) = 1.25 mg/kg bw/day

--------------------------------------------------------------------------------

Food Crop Residue Adj.Factors Comment

EPA Code Grp Food Name (ppm) 

 #1 #2 

-------- ---- ------------------------------- ---------- ------ ------ -------

21000440 M Beef, meat 0.010000 1.000 1.000 

21000441 M Beef, meat-babyfood 0.010000 1.000 1.000 

21000450 M Beef, meat, dried 0.010000 1.920 1.000 

21000460 M Beef, meat byproducts 0.050000 1.000 1.000 

21000461 M Beef, meat byproducts-babyfood 0.050000 1.000 1.000 

21000470 M Beef, fat 0.010000 1.000 1.000 

21000471 M Beef,fat-babyfood 0.010000 1.000 1.000 

21000480 M Beef, kidney 0.050000 1.000 1.000 

21000490 M Beef, liver 0.050000 1.000 1.000 

21000491 M Beef, liver-babyfood 0.050000 1.000 1.000 

15001200 15 Corn, field, flour 0.100000 1.000 1.000 

15001201 15 Corn, field, flour-babyfood 0.100000 1.000 1.000 

15001210 15 Corn, field, meal 0.100000 1.000 1.000 

15001211 15 Corn, field, meal-babyfood 0.100000 1.000 1.000 

15001220 15 Corn, field, bran 0.100000 1.000 1.000 

15001230 15 Corn, field, starch 0.100000 1.000 1.000 

15001231 15 Corn, field, starch-babyfood 0.100000 1.000 1.000 

15001240 15 Corn, field, syrup 0.100000 1.500 1.000 

15001241 15 Corn, field, syrup-babyfood 0.100000 1.500 1.000 

15001250 15 Corn, field, oil 0.100000 1.000 1.000 

15001251 15 Corn, field, oil-babyfood 0.100000 1.000 1.000 

15001260 15 Corn, pop 0.100000 1.000 1.000 

15001270 15 Corn, sweet 0.100000 1.000 1.000 

15001271 15 Corn, sweet-babyfood 0.100000 1.000 1.000 

23001690 M Goat, meat 0.010000 1.000 1.000 

23001700 M Goat, meat byproducts 0.050000 1.000 1.000 

23001710 M Goat, fat 0.010000 1.000 1.000 

23001720 M Goat, kidney 0.050000 1.000 1.000 

23001730 M Goat, liver 0.050000 1.000 1.000 

24001890 M Horse, meat 0.010000 1.000 1.000 

27002220 D Milk, fat 0.010000 1.000 1.000 

27002221 D Milk, fat - baby food/infant for 0.010000 1.000 1.000 

27012230 D Milk, nonfat solids 0.010000 1.000 1.000 

27012231 D Milk, nonfat solids-baby food/in 0.010000 1.000 1.000 

27022240 D Milk, water 0.010000 1.000 1.000 

27022241 D Milk, water-babyfood/infant form 0.010000 1.000 1.000 

27032251 D Milk, sugar (lactose)-baby food/ 0.010000 1.000 1.000 

29003120 M Rabbit, meat 0.010000 1.000 1.000 

26003390 M Sheep, meat 0.010000 1.000 1.000 

26003391 M Sheep, meat-babyfood 0.010000 1.000 1.000 

26003400 M Sheep, meat byproducts 0.050000 1.000 1.000 

26003410 M Sheep, fat 0.010000 1.000 1.000 

26003411 M Sheep, fat-babyfood 0.010000 1.000 1.000 

26003420 M Sheep, kidney 0.050000 1.000 1.000 

26003430 M Sheep, liver 0.050000 1.000 1.000 

86010000 O Water, direct, all sources 0.000685 1.000 1.000 

86020000 O Water, indirect, all sources 0.000685 1.000 1.000 
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Attachment 2. Results of the chronic dietary exposure and risk assessment for nicosulfuron.

U.S. Environmental Protection Agency Ver. 2.00

DEEM-FCID Chronic analysis for NICOSULFURON (1994-98 data)

Residue file name: C:\Documents and Settings\mdoherty\My Documents\Chemistry 

Reviews\Nicosulfuron\129008 - 2009 Chronic.R98

 Adjustment factor #2 NOT used.

Analysis Date 09-30-2009/11:44:41 Residue file dated: 09-30-2009/11:44:06/8

Reference dose (RfD, Chronic) = 1.25 mg/kg bw/day

===============================================================================

 Total exposure by population subgroup

-------------------------------------------------------------------------------

 Total Exposure

 -----------------------------------

 Population mg/kg Percent of 

 Subgroup body wt/day Rfd 

-------------------------------------- ------------- ---------------

U.S. Population (total) 0.000300 0.0%

U.S. Population (spring season) 0.000302 0.0%

U.S. Population (summer season) 0.000315 0.0%

U.S. Population (autumn season) 0.000295 0.0%

U.S. Population (winter season) 0.000288 0.0%

Northeast region 0.000273 0.0%

Midwest region 0.000325 0.0%

Southern region 0.000294 0.0%

Western region 0.000308 0.0%

Hispanics 0.000351 0.0%

Non-hispanic whites 0.000291 0.0%

Non-hispanic blacks 0.000316 0.0%

Non-hisp/non-white/non-black 0.000278 0.0%

All infants (< 1 year) 0.000454 0.0%

Nursing infants 0.000134 0.0%

Non-nursing infants 0.000576 0.0%

Children 1-6 yrs 0.000773 0.1%

Children 7-12 yrs 0.000517 0.0%

Females 13-19 (not preg or nursing) 0.000310 0.0%

Females 20+ (not preg or nursing) 0.000181 0.0%

Females 13-50 yrs 0.000247 0.0%

Females 13+ (preg/not nursing) 0.000248 0.0%

Females 13+ (nursing) 0.000239 0.0%

Males 13-19 yrs 0.000412 0.0%

Males 20+ yrs 0.000215 0.0%

Seniors 55+ 0.000147 0.0%

Children 1-2 yrs 0.000835 0.1%

Children 3-5 yrs 0.000766 0.1%

Children 6-12 yrs 0.000540 0.0%

Youth 13-19 yrs 0.000362 0.0%

Adults 20-49 yrs 0.000225 0.0%

Adults 50+ yrs 0.000151 0.0%

Females 13-49 yrs 0.000226 0.0%

-------------------------------------------------------------------------------