UNITED ST A TES ENVIRONMENT AL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

Date: 15 September 2015 

SUBJECT: Chlorimuron Ethyl. Draft Human Health Risk Asstssment in Support of 

Registration Review. 

FROM: 

THROUGH: 

TO: 

PC Code: 12890 I 

Decision No.: 502175 

Petition No.: NA 

Risk Assessment Type: Single Chemical 

Aggregate 

TXR No.: NA 

MRID No.: None 

DP Barcode: 0426094 

Registration No.: NA 

Regulatory Action: Registration Review 

Case No.: 7403 

CAS No.: 90982-32-4 

40 CFR: 180.429 

Michael A. Doherty, Ph.D., Chemist ,, crv 

Karlyn Middleton, M.S., Toxicologist 

Zaida Figueroa, DrPH, Industrial Hygienist 

Risk Assessment Branch II 

Health Effects Division (7509P) · 

Christina 

Risk Assessment 

Swartz, 

Branch 

Branch 

II 

Chief ~ ~ 

Health Effects Division (7509P) 

Wilhemena Livingston, Chemical Review Manager 

Kevin Costello, Branch Chief 

Risk Management and Implementation Branch IV (RM lB IV) 

Pesticide Re-Evaluation Division (7508P) 

As part of registration review, HED has examined the toxicological and exposure databases for 

assessing human health risks associated with chlorimuron ethyl and conducted a new risk 

assessment following current practices and policies. Significant changes relative to the last risk 

assessment (D358796, W. Cutchin, 14 Sept. 2009) include: 

• Establishment of endpoints and points of departure for assessing acute dietary exposure, 

dermal exposure for children, and incidental oral exposure for children; 

• Assessment of acute dietary risk for all population groups; and 

• Assessment of spray drift risk for adults and children. 

Page 1of 46 
1.0 

2.0 

2.1 

2.2 

3.0 

3. 1 

3.2 

3.3 

4.0 

4.1 

4.2 

4.3 

4.4 

5.0 

5.1 

5.2 

5.3 

Table of Contents 

Executive Summary ........................................................................................................... 3 

HED Recommendations .................................................................................................... 4 

Tolerance Considerations ................................................................................................ 4 

Label Considerations ....................................................................................................... 5 

Introduction ........................................................................................................................ 5 

Chemical Identity and Physical/Chemical Characteristics ............................................... 5 

Pesticide Use Pattern and Anticipated Exposure Pathways ............................................. 5 

Consideration of Environmental Justice .......................................................................... 6 

Hazard Identification/Toxicology ..................................................................................... 7 

Summary of Toxicological Effects ............................ ................ ........ .............................. 7 

Safety Factor for Infants and Children (FQPA Safety Factor) ......................................... 8 

Toxicity Endpoint and Point of Departure Selections ...................................................... 9 

Endocrine Disruptor Screening Program ....................................................................... 11 

Dietary Exposure and Risk Assessment ......................................................................... 12 

Water Residue Profile .................................................................................................... 12 

Food Residue Profile ...................................................................................................... 13 

Dietary Exposure and Risk Estimates ............................................................................ 13 

6.0 Residential (Non-Occupational) Exposure/Risk Characterization ............................. 14 

6.1 Spray Drift ................................ ................ .................... .................................................. 14 

6.1. l Combined Risk Estimates from Lawn Deposition Adjacent to Applications .............. 14 

6.2 Residential Bystander Post-Application Inhalation Exposure ....................................... 15 

7.0 Aggregate Exposure/Risk Characterization .................................................................. 16 

8.0 Cumulative Exposure/Risk Characterization ............................................................... 16 

9.0 Occupational Exposure/Risk Characterization ............................................................ 16 

9.1 Occupational Handler Exposure/Risk Estimates ............................................................ 16 

9.2 Occupational Post-application Exposure/Risk Estimates .............................................. 19 

9.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates ........................... 20 

9.2.2 Occupational Post-application Dermal Exposure/Risk Estimates ............................... 20 

10.0 Public Health and Pesticide Epidemiology Data ........................................................... 22 

11.0 Literature References ...................................................................................................... 23 

12.0 References ......................................................................................................................... 23 

Appendix A. 

Appendix B. 

Appendix C. 

Appendix D. 

Appendix E. 

Appendix F. 

Toxicology Data Requirements and Toxicology Profile ................................ 24 

Revie\v of Human Research ............................................................................. 29 

Occupational Non-cancer Algorithms ............................................................. 29 

Dietary Exposure/Risk Modeling Input and Output ..................................... 31 

Nomenclature and Physical/Chemical Properties .......................................... 44 

Spray Drift Detailed Description ..................................................................... 45 

Page 2of 46 
Page 3 of 46

1.0 Executive Summary

Chlorimuron ethyl {ethyl 2-[[[[(4-chloro-6-methoxy-2-pyrimidinyl)amino]carbonyl]amino]-

sulfonyl]benzoate} is a herbicide of the sulfonylurea class. Its mode of action is through 

inhibition of the plant enzyme acetolactate synthase, which is also known as acetohydroxy acid 

synthase. Inhibition of this enzyme blocks branched-chain amino acid biosynthesis of valine, 

leucine, and isoleucine (involved in plant growth) processes and leads to death of the plant.

Chlorimuron ethyl is registered for use on soybeans, field corn, peanuts, low growing berries 

(subgroup 13-07H, except strawberry) and non-crop areas such as fence rows and roadsides for the 

control of broadleaf weeds and grasses. 

The last human health risk assessment for chlorimuron ethyl was completed in 2009 (D370361, 

W. Cutchin). A human health scoping document was conducted for chlorimuron ethyl in 2010

(D379636, D. McNeilly). Identified data needs included acute and subchronic neurotoxicity 

studies in the rat, an immunotoxicity study, a 21- or 28-day dermal toxicity study in the rat or rabbit, 

and a rat 90-day subchronic inhalation study. At this time, all of the required studies have been 

submitted or waived, and both the toxicology and exposure databases for chlorimuron ethyl are

considered complete and adequate for risk assessment. This draft risk assessment incorporates all 

new data and includes updates to hazard and exposure assessments, science policies, and 

procedures. 

For dietary exposure, HED has conducted screening-level acute and chronic dietary risk 

assessments for chlorimuron ethyl using tolerance-level residues in foods and a sulfonylureaclass-wide screening-level estimate of residues in drinking water. Dietary risk estimates range 

from 3 to 13% (acute) and from 8 to 30% (chronic) of the population adjusted doses (PADs) and 

are below HED’s level of concern (LOC).

There are no registered residential uses or uses resulting in direct residential exposure associated 

with chlorimuron ethyl. Therefore, a quantitative residential exposure assessment was not 

performed. However, chlorimuron ethyl can be applied via groundboom and aerial equipment

and, therefore, there is the potential for indirect exposure to chlorimuron ethyl as a result of spray 

drift. Based on this, HED estimated risks associated with spray drift. The resulting risk estimates 

are not of concern (margins of exposure (MOEs) ≥ 23,000 with a level of concern (LOC) of 

100).

Due to the lack of uses in a residential setting, aggregate exposure and risk estimates are 

equivalent to the dietary exposure and risk estimates and do not exceed HED’s level of concern.

No chemical-specific handler exposure data were submitted in support of this draft risk 

assessment; therefore, HED relied on the best available data to assess handler exposure. Default 

assumptions established by HED’s Science Advisory Council for Exposure (ExpoSAC) were 

used for parameters such as body weight and amount handled. All occupational handler scenarios 

for the registered uses resulted in MOEs ranging from 860 to 1,900,000. As these are greater 

than the LOC of 100 at risk mitigation ranging from baseline attire (with no gloves or respirator)

to engineering controls (for aerial applications such as enclosed cockpits) they reflect risk 

estimates that are not of concern. 
Page 4 of 46

Based on the Agency's current practices, a quantitative non-cancer occupational post-application 

inhalation exposure assessment was not performed for chlorimuron ethyl. If new policies or 

procedures are put into place, the Agency may revisit the need for such an assessment. 

The restricted entry interval (REI) of 12 hours specified on the registered labels is based on the 

acute toxicity of chlorimuron ethyl and is adequate to protect agricultural workers from postapplication exposures.

HED has not identified any risk concerns associated with the registered uses of chlorimuron 

ethyl. There are no data gaps that would require submission of additional toxicity, residue 

chemistry, or exposure data.

2.0 HED Recommendations

2.1 Tolerance Considerations

The existing tolerances (40 CFR 180.429) are supported by the available residue chemistry data. 

At this time, there is a Canadian MRL for residues of chlorimuron ethyl in soybeans at 0.05 ppm; 

there are no other Canadian MRLs and no Codex MRLs for chlorimuron ethyl. The U.S. 

tolerance for residues of chlorimuron ethyl in soybean, seed is 0.05 ppm and is harmonized with 

the Canadian MRL. No revisions to the existing U.S. tolerances are needed during registration 

review. 

An analytical reference standard for chlorimuron ethyl is currently available in EPA’s National 

Pesticide Standards Repository (NPSR) and has an expiration date of 22 January 2019 (email 

communication between G. Verdin and J. Van Alstine, 5/11/2015). The registrant is required to 

maintain reasonable amounts of the reference standards for chlorimuron ethyl in the NPSR as 

long as tolerances remain published in 40 CFR §180.429. When necessary, new reference 

standards, or updated certificates of analysis (COAs), should be sent to the Analytical Chemistry 

Branch (ACB), which is located at Fort Meade, MD. It should be sent to the attention of either 

Theresa Cole or Thuy Nguyen at the address listed below, along with a letter of transmittal. 

Please note that the full 9-digit ZIP Code is required, or the mail will be returned to the 

registrant. 

 USEPA

 National Pesticide Standards Repository

 Analytical Chemistry Branch/BEAD/OPP

 701 Mapes Road

 Fort George G. Meade, MD 20755-5350

The letter of transmittal should include the assay of the standard, name of the analytical method 

used, a statement of principal impurities, purification procedures employed, storage 

requirements, and special precautions for safe handling. Replacement of standards, or updated 

COAs, may be required periodically if supplies are exhausted, if the standards expire, or if 

decomposition occurs during storage. Safety Data Sheets (SDSs) must accompany all analytical 
Page 5 of 46

standards as specified by the Occupational Safety and Health Administration (OSHA) in 29CFR 

§1910.1200. 

2.2 Label Considerations

The current labels for chlorimuron don’t require enclosed cockpits for aerial applications; HED 

recommends that PRD ensure that the registered labels state the need of enclosed cockpits for 

aerial equipment.

3.0 Introduction

3.1 Chemical Identity and Physical/Chemical Characteristics

Chlorimuron ethyl {ethyl 2-[[[[(4-chloro-6-methoxy-2-pyrimidinyl)amino]carbonyl]amino]-

sulfonyl]benzoate} is a systemic herbicide belonging to the pyrimidinylsulfonylurea class of 

chemicals. The chemical properties of chlorimuron ethyl do not suggest that there are any 

particular exposure issues that warrant special consideration. The compound has a dissociation 

constant of 4.2 at 25°C, making its water solubility dependent on pH, with low solubility below 

pH 3. The potential for chlorimuron ethyl to partition into fatty matrices is also, by extension, pH 

dependent; however, based on the octanol/water partitioning coefficients, such partitioning is 

unlikely to occur at physiological pH levels. Chlorimuron ethyl has a relatively low vapor 

pressure, indicating that inhalation of vapors is unlikely to be a significant source of exposure 

under ambient conditions. The nomenclature and physical/chemical properties of chlorimuron 

ethyl are provided in Appendix E.

3.2 Pesticide Use Pattern and Anticipated Exposure Pathways

Chlorimuron ethyl is registered for use on soybeans, field corn, peanuts, low growing berries 

(subgroup 13-07H, except strawberry) and non-crop areas such as fence rows and roadsides. There 

are 22 registered end-use products, all of which are forms of dry-flowable formulations. The 

registered application methods for chlorimuron ethyl include the use of aerial and ground 

equipment.

The registered use patterns allows one or two application per season; therefore, the duration of 

exposure for occupational handlers is expected to be short-term (i.e., 1 to 30 days) and 

intermediate-term (i.e., 1 to 6 months); long-term exposures (greater than 6 months) are not 

anticipated. The PPE statements on registered labels require applicators, flaggers and other 

handlers to wear the following: long sleeved shirt, long pants, shoes plus socks, and chemicalresistant gloves. The restricted entry interval (REI) on all labels is 12 hours.

Exposure Pathways

Individuals may be exposed to chlorimuron ethyl via their diet (food and drinking water). There 

are no registered uses for chlorimuron ethyl that will result in direct non-dietary (i.e., residential) 

exposures. However, there is the potential for indirect exposure (incidental oral and dermal) to 
Page 6 of 46

chlorimuron ethyl related to spray drift. Agricultural workers may be exposed to chlorimuron 

ethyl during mixing, loading, and/or applying the herbicide (dermal and inhalation routes) as 

well as during post-application activities (dermal route).

Table 3.2. Summary of Directions for Registered Uses of Chlorimuron ethyl.

Applic. 

Timing, 

Type, and 

Equip.

Formulation and 

Products

[EPA Reg No.]

Applic. 

Rate

(lb 

ai/A)

Max. No. 

Applic. per 

Season

Max. 

Seasonal 

Applic. Rate 

(lb ai/A)

Use Directions and Limitations

Field Corn

Ground 

band or 

broadcast, 

aerial

25% a.i. (DG)

[352-436]

0.005-

0.063 

2 0.063 Product may be applied crop preplant, pre- and post-emergence, 

and post-harvest as a burn down.

Application interval = 7 days

Pre-harvest interval = 7 days

Cranberry

Ground 

broadcast, 

aerial

25% a.i. (DG)

[WA100004]

0.016 1 0.016 Product may be applied early post 

weed emergence

Pre-harvest interval = 60 days

Only for use in the state of 

Washington

Peanut

Ground 

band or 

broadcast, 

aerial

25% a.i. (DG)

[352-436]

25% a.i. (DG)

[71368-82]

0.0078 1 0.0078 Product may be applied 60 days after 

crop emergence to 45 days before 

harvest.

Pre-harvest interval = 45 days

Soybean

Ground 

band or 

broadcast, 

aerial

279-3179, 279-3184, 

352-436, 352-444, 352-

573, 352-574, 352-589, 

352-596, 352-599, 352-

635, 352-648, 352-650, 

352-749, 352-756, 352-

757, 59639-116, 59639-

117, 71368-82, 71368-

83, 71368-84 and 85588-

5 (% ai varies from 8.3–

31.8% in products)

0.0047-

0.063

2 0.063 Apply after the first trifoliate has 

opened, but not later than 60 days 

before maturity.

Application interval = 2-3 weeks

Pre-harvest interval = Do not apply

later than the flowering stage

Do not graze treated fields or harvest 

for forage or hay.

Non-crop land (fence rows, roadsides, equipment storage, and similar areas)

Ground 

band or 

broadcast, 

aerial

25% a.i. (DG)

[352-436]

25% a.i. (DG)

[71368-82]

0.016-

0.031

2 0.063 Apply to weeds, post-emergent

3.3 Consideration of Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, were considered in the 

preliminary human health risk assessment for chlorimuron ethyl, in accordance with U.S. 

Executive Order 12898, "Federal Actions to Address Environmental Justice in Minority 
Page 7 of 46

Populations and Low-Income Populations."

1 As a part of every pesticide risk assessment, OPP 

considers a large variety of consumer subgroups according to well-established procedures. In 

line with OPP policy, HED estimates risks to population subgroups from pesticide exposures that 

are based on patterns of that subgroup’s food and water consumption, and activities in and 

around the home that involve pesticide use in a residential setting. Extensive data on food 

consumption patterns are compiled by the USDA under the National Health and Nutrition 

Examination Surveys/What We Eat in America (NHANES/WWEIA) and are used in pesticide 

risk assessments for all registered food uses of a pesticide. These data are analyzed and 

categorized by subgroups based on age and ethnic group. Additionally, OPP is able to assess 

dietary exposure to smaller, specialized subgroups and exposure assessments are performed 

when conditions or circumstances warrant. Whenever appropriate, non-dietary exposures based 

on home use of pesticide products and associated risks for adult applicators and for toddlers, 

youths, and adults entering or playing on treated areas post-application are evaluated. Further 

considerations are currently in development as OPP has committed resources and expertise to the 

development of specialized software and models that consider exposure to bystanders and farm 

workers as well as lifestyle and traditional dietary patterns among specific subgroups. 

4.0 Hazard Identification/Toxicology

The toxicology database for chlorimuron ethyl is complete and adequate for risk assessment. 

Immunotoxicity and inhalation studies are not available for chlorimuron ethyl, as required in 

accordance with the current Part 158 Guidelines (40 CFR Part 158). However, the Hazard and 

Science Policy Council (HASPOC) determined that the subchronic inhalation (TXR# 0056401) 

and immunotoxicity studies are not required for chlorimuron ethyl. The immunotoxicity 

requirement has been waived for the entire sulfonylurea class of chemicals (TXR#0056723). 

Since the last risk assessment (D358796, D. McNeilly, 14 September 2009), new acute and 

subchronic neurotoxicity and dermal toxicity studies have been submitted. The toxicological 

endpoints and points of departure (PODs) have been updated based on the new toxicology data, 

and new acute dietary and incidental oral risk assessments have been conducted. Also, the 

dermal risk assessment has been revised, and a separate children’s dermal risk assessment has 

been conducted since the adult dermal assessment is based on a developmental endpoint (not 

appropriate for children’s exposure). All other endpoints/PODs selected for risk assessment 

remain the same as in previous assessments. See Appendix A for the chlorimuron ethyl

toxicological profile. 

4.1 Summary of Toxicological Effects

A variety of effects were seen after oral exposure to chlorimuron ethyl. After subchronic 

exposure, decreased body weight/body weight gain and liver effects (increased weights and 

margination of hepatocyte cytoplasmic content) were observed in rats. After chronic exposure, 

effects in the rat were limited to decreased body weight and body weight gain; no liver effects 

were observed. In dogs, hematological changes (decreased erythrocyte count, hematocrit, and 

hemoglobin concentration) were primarily seen after both subchronic and chronic exposure. 

Increased liver weights and atrophy of the thymus and prostate were also observed in dogs after 

 

1 http://www.epa.gov/compliance/resources/policies/ej/exec_order_12898.pdf
Page 8 of 46

subchronic exposure. However, these effects were not seen in chronic dog studies. No treatmentrelated effects were seen in mice after subchronic or chronic exposure. There was no evidence of 

carcinogenicity observed in the mouse or rat carcinogenicity studies. In addition, there was no 

indication of mutagenicity in the battery of available studies.

 

No treatment related effects were observed after dermal exposure to chlorimuron ethyl at doses 

up to the limit dose. Clinical signs were observed in acute and subchronic neurotoxicity studies. 

In the acute study, reduced arousal and reduced motor activity were seen in male and female rats

at the mid and high dose. At the high dose, males preferred a curled up posture compared to 

controls and there was an increased incidence of palpebral closure. In the subchronic 

neurotoxicity study, effects observed were decreased body weight/body weight gain and reduced 

food consumption in females at the high dose. No treatment-related neurotoxic effects were 

observed in the study.

 

Increased quantitative susceptibility of the young was observed in rabbit developmental and rat 

reproduction toxicity studies. In the rabbit developmental study, delayed ossification was seen in 

fetuses in the absence of maternal toxicity. In the rat reproduction study, decreased body weight 

and histopathology in the cerebellum (cellular changes in the internal granular and external 

germinal layers) were seen in pups in the absence of maternal toxicity. The changes observed in 

the cerebellum were not associated with neurotoxicity or neurobehavioral changes, and not 

observed in other rat reproduction studies available for chlorimuron at similar doses. 

Additionally, there was no evidence of increased susceptibility observed in the other 

reproduction studies. 

In acute lethality studies, chlorimuron ethyl has low or minimal acute toxicity via the oral 

(category IV), dermal (category III), and inhalation routes of exposure (category IV). It is mildly 

irritating to the eye (category III) and non-irritating to the skin (category IV); it is not a skin 

sensitizer.

Chlorimuron ethyl is well absorbed from the gastrointestinal tract, extensively metabolized and 

excreted approximately equally between the urine and feces. Unchanged parent compound was 

identified, primarily in the urine. In the feces at 24 hrs post-dosing, less than 10% of the 

radioactivity was identified as the parent compound. Radioactivity was distributed throughout 

the body, with the highest levels observed in the liver, and a half-life of 50 hrs; retention of 

radioactivity in tissues was insignificant by 168 hrs post-dosing. 

4.2 Safety Factor for Infants and Children (FQPA Safety Factor)

HED recommends that the FQPA Safety Factor be reduced to 1x for chlorimuron ethyl. The 

toxicology database is complete, and there no concerns/residual uncertainties with regard to preand/or postnatal toxicity, and no concern for neurotoxicity. Although increased quantitative 

susceptibility was seen in the rabbit developmental and rat reproduction studies, the fetal effect 

seen in rabbits was limited to delayed ossification and increased susceptibility was not seen in a 

rat developmental study. The effects observed in the rat reproduction study (histopathology in 

the cerebellum) were not reproduced in two other rat reproduction studies at similar doses. 

Additionally, there are clear NOAELs for the fetal/offspring effects seen in the studies. 
Page 9 of 46

Furthermore, the endpoints and points of departure selected for risk assessment are protective of

the effects observed in the studies. 

4.3 Toxicity Endpoint and Point of Departure Selections

The toxicological endpoints and points of departure (PODs) used for risk assessment have been 

updated considering new toxicology data which includes a dermal toxicity study, as well as acute 

and subchronic neurotoxicity studies. An acute dietary risk assessment has been conducted since 

treatment related effects were noted in the new acute neurotoxicity study. An endpoint/POD for 

incidental oral exposure has also been selected for use in a spray drift assessment. No treatment 

related effects were seen in the new dermal toxicity study at doses up to the limit dose. However, 

increased susceptibility was seen in developmental and reproduction studies. Therefore, the 

developmental rabbit, with the lowest point of departure, was used for adult dermal risk 

assessment to protect for potential sensitivity. The endpoint (delayed ossification) observed in 

fetuses in the developmental rabbit study is not relevant for assessing kids dermal risk. 

Therefore, the reproduction study (with a higher POD) was used for assessing children’s dermal 

risk. All other endpoints/PODs selected for risk assessment remain the same as in previous 

assessments. It should be noted that the endpoints and points of departure (POD) presented in the 

toxicology profile table (appendix X) have not been updated to comply with current policy. The 

NOAELs and LOAELS have not been changed. Therefore, the endpoints/PODs selected for risk 

assessment may be conservative. The PODs selected for risk assessment are protective of the 

effects observed in the chlorimuron toxicology database. A summary of toxicological doses and 

endpoints used in the chlorimuron ethyl human health risk assessments is presented below:

Table 4.3.1. Toxicological Doses and Endpoints for Chlorimuron ethyl for Use in Dietary and Non-Occupational 

Human Health Risk Assessments.

Exposure/

Scenario

Point of 

Departure

Uncertainty/

FQPA Safety 

Factors

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Acute Dietary (All 

populations)

NOAEL = 

100 

mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 

1X

Acute RfD =1 

mg/kg/day

aPAD = 1 

mg/kg/day 

Acute Neurotoxicity-Rat, LOAEL=500 

mg/kg/day, based on reduced arousal 

and reduced motor activity in male and 

female rats

Incidental oral 

(short-term)

NOAEL = 

9.0 

mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 

1X

Residential 

LOC for MOE 

= 100

Co-critical studies

90-day oral toxicity – dogs

LOAEL = 42.7 mg/kg/day, based on 

hematological changes (increased 

hematocrit, hemoglobin, erythrocyte 

counts) atrophy of the thymus and 

prostate, increased absolute and relative 

liver weights.

Chronic toxicity – dogs

LOAEL = 50 mg/kg/day, based on mild 

anemia.
Page 10 of 46

Table 4.3.1. Toxicological Doses and Endpoints for Chlorimuron ethyl for Use in Dietary and Non-Occupational 

Human Health Risk Assessments.

Exposure/

Scenario

Point of 

Departure

Uncertainty/

FQPA Safety 

Factors

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Children’s Dermal 

Short- (1-30 days) 

and Intermediateterm (1-6 months)

Offspring 

NOAEL = 

17/21mg/kg/d

ay

*DAF=4.8%

UFA = 10X

UFH = 10X

FQPA SF = 

1X 

Residential 

LOC for MOE 

= 100

2 generation reproduction-rats

Offspring LOAEL-Rat = 177/214 

mg/kg/day, based on reduced pup weight 

in both generations (up to 20%) and 

histopathological findings in the 

cerebellum (cellular changes in the 

internal granular and external germinal 

layers). Effects observed in the absence 

of maternal effects.

Chronic Dietary 

(All Populations)

NOAEL = 9 

mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 

1X

Chronic RfD = 

0.09 

mg/kg/day

cPAD = 0.09 

mg/kg/day

Co-critical studies

90-day oral toxicity – dogs

LOAEL = 42.7 mg/kg/day, based on 

hematological changes (increased 

hematocrit, hemoglobin, erythrocyte 

counts) atrophy of the thymus and 

prostate, increased absolute and relative 

liver weights.

Chronic toxicity – dogs

LOAEL = 50 mg/kg/day, based on mild 

anemia.

Cancer (oral, 

dermal, inhalation)

“Not Likely to be Carcinogenic to Humans.”

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). UFL = use of a LOAEL to extrapolate a NOAEL. UFS = use of a short-term study for long-term risk assessment. 

UFDB = to account for the absence of key data (i.e., lack of a critical study). FQPA SF = FQPA Safety Factor. PAD = population 

adjusted dose (a = acute, c = chronic). RfD = reference dose. MOE = margin of exposure. LOC = level of concern. N/A = not 

applicable. *Dermal absorption factor based on a comparison between the dermal toxicity and the oral rabbit developmental 

toxicity studies using a ratio of the oral LOAEL and dermal NOAEL [i.e., (48/1000)*100].

Table 4.3.2. Summary of Toxicological Doses and Endpoints for Chlorimuron ethyl for Use in Occupational 

Human Health Risk Assessments.

Exposure/

Scenario

Point of 

Departure

Uncertainty 

Factors

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Adult Dermal (1-

30 days) and 

Intermediate-term 

(1-6 months)

Development

al NOAEL = 

13 mg/kg/day

DAF=4.8%

UFA = 10X

UFH = 10X

FQPA SF = 

1X 

Occupational 

LOC for MOE 

= 100

Developmental Toxicity-Rabbit 

Developmental LOAEL = 48 

mg/kg/day, based on delayed 

ossification in fetuses in the absence of 

maternal effects.
Page 11 of 46

Table 4.3.2. Summary of Toxicological Doses and Endpoints for Chlorimuron ethyl for Use in Occupational 

Human Health Risk Assessments.

Exposure/

Scenario

Point of 

Departure

Uncertainty 

Factors

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Inhalation Short-

(1-30 days) and 

Intermediate-term 

(1-6 months)

NOAEL = 9.0 

mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 

1X

Occupational 

LOC for MOE 

= 100

Co-critical studies

90-day oral toxicity – dogs

LOAEL = 42.7 mg/kg/day, based on 

hematological changes (increased 

hematocrit, hemoglobin, erythrocyte 

counts) atrophy of the thymus and 

prostate, increased absolute and 

relative liver weights.

Chronic toxicity – dogs

LOAEL = 50 mg/kg/day, based on 

mild anemia.

Cancer (oral, 

dermal, inhalation)

“Not Likely to be Carcinogenic to Humans.”

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). UFL = use of a LOAEL to extrapolate a NOAEL. UFS 

= use of a short-term study for long-term risk assessment. UFDB = to account for the absence of key data (i.e., lack of a critical study). FQPA SF 

= FQPA Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). RfD = reference dose. MOE = margin of exposure. LOC = level 

of concern. N/A = not applicable.

4.4 Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its most recent registration decision for chlorimuron ethyl, EPA 

reviewed these data and selected the most sensitive endpoints for relevant risk assessment 

scenarios from the existing hazard database. However, as required by FFDCA section 408(p), 

chlorimuron ethyl is subject to the endocrine screening part of the Endocrine Disruptor 

Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 
Page 12 of 46

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 

2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, 

which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals 

identified for EDSP screening was published on June 14, 20132and includes some pesticides 

scheduled for Registration Review and chemicals found in water. For further information on the 

status of the EDSP, the policies and procedures, the lists of chemicals, future lists, the test 

guidelines and the Tier 1 screening battery, please visit our website.3

5.0 Dietary Exposure and Risk Assessment 

5.1 Water Residue Profile

Screening groundwater-sourced drinking water exposure estimates were generated with the 

Pesticide Root Zone Model for GroundWater (PRZM-GW; v.1.07) for use in the sulfonylurea 

(SU) dietary risk assessments. Rather than produce chemical-specific estimated drinking water 

concentrations (EDWCs) following the usual assessment procedures, EFED provided coarsescreen estimates that should exceed upper-bound, chemical-specific EDWCs for any SU. This 

was achieved by using model inputs that represent the use pattern of highest exposure from any 

SU, the highest soil mobility of any SU residue of concern, and the highest persistence to any 

route of degradation over time. The resulting coarse-screen EDWCs from PRZM-GW were used 

as conservative estimates of exposure and are summarized in Table 5.1 (D427429, G. Orrick). 

The acute and chronic dietary assessments for chlorimuron ethyl used the coarse-screen 

maximum daily concentration of 751 μg/L (0.751 ppm) and the post-breakthrough mean value of 

492 μg/L (0.492 ppm), respectively. 

Table 5.1. PRZM-GW Coarse-Screen EDWCs for Sulfonylureas1.

Modeled Scenario Kd or KOC

Initial Application 

Dates (days postemergence)

Max. Daily Conc. 

(μg/L)

Mean 

Breakthrough 

Time (yrs)

Postbreakthrough 

Mean (μg/L)

WI corn Kd 7 449 11.5 415

KOC 7 504 6.9 425

DMV corn Kd 7 489 5.3 369

KOC 7 560 3.3 378

FL citrus Kd 7 429 3.2 351

KOC 7 467 2.3 349

FL potato Kd 7 375 2.6 272

 

2 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list 

of chemicals.

3 http://www.epa.gov/endo/
Page 13 of 46

Table 5.1. PRZM-GW Coarse-Screen EDWCs for Sulfonylureas1.

Modeled Scenario Kd or KOC

Initial Application 

Dates (days postemergence)

Max. Daily Conc. 

(μg/L)

Mean 

Breakthrough 

Time (yrs)

Postbreakthrough 

Mean (μg/L)

KOC 7 407 2.2 275

GA peanut Kd 7 197 5.2 156

KOC 7 206 3.9 158

NC cotton Kd 7 640 8.7 492

Kd 37 641 8.7 491

Kd 67 637 8.7 490

KOC 7 742 5.7 484

KOC 37 751 5.7 483

KOC 67 744 5.7 482

1 Maximum values are bolded.

5.2 Food Residue Profile 

Chlorimuron ethyl is registered for use on, and tolerances have been established for residues of 

chlorimuron ethyl in or on, corn (grain at 0.01 ppm), low-growing berry except strawberry (crop 

subgroup 13-07H at 0.02 ppm), peanut (0.02 ppm), and soybean (seed at 0.05 ppm). In 

conducting this assessment, HED has assumed tolerance-level residues in those raw agricultural 

commodities and processed products, and that 100 percent of those crops are treated with 

chlorimuron ethyl.

5.3 Dietary Exposure and Risk Estimates

Exposure and risk estimates were obtained from the Dietary Exposure Evaluation Model using 

the Food Commodity Intake Database (DEEM-FCID; version 3.18). The model uses food 

consumption data from the 2003-2008 NHANES/WWEIA database, coupled with recipe files 

and residues in foods, to derive estimates of dietary exposure and risk. Generally, HED is 

concerned when dietary exposure estimates exceed 100% of the population adjusted dose (PAD). 

In the case of chlorimuron ethyl, the dietary risk estimates (Table 5.3) are below HED’s level of 

concern, ranging from 2 to 4% of the acute PAD (aPAD) and from 3 to 10% of the chronic PAD 

(cPAD). Because of the very conservative assumptions used in the analysis (tolerance level 

residues, 100 % crop treated, upper-bound modeled drinking water estimates), actual exposure 

and risk are expected to be much lower than those shown in Table 5.3. The listings of inputs and 

outputs to the assessment are included in Appendix D. 

Table 5.3. Summary of dietary exposure and risk estimates for chlorimuron ethyl.

Acute Estimates (95th Percentile) Chronic Estimates

Population Group

Exposure, mg/kg 

bw Risk, % aPAD

Exposure, mg/kg 

bw/day Risk, % cPAD

Total US Population 0.0410 4 0.0103 12

All Infants (< 1 year old) 0.128 13 0.0267 30

Children 1-2 years old 0.0633 6 0.0150 17

Children 3-5 years old 0.0513 5 0.0126 14
Page 14 of 46

Table 5.3. Summary of dietary exposure and risk estimates for chlorimuron ethyl.

Acute Estimates (95th Percentile) Chronic Estimates

Population Group

Exposure, mg/kg 

bw Risk, % aPAD

Exposure, mg/kg 

bw/day Risk, % cPAD

Children 6-12 years old 0.0391 4 0.00910 10

Youth 13-19 years old 0.0342 3 0.00756 8

Adults 20-49 years old 0.0404 4 0.0103 12

Adults 50-99 years old 0.0360 4 0.0102 11

Female 13-49 years old 0.0409 4 0.0103 11

6.0 Residential (Non-Occupational) Exposure/Risk Characterization

There are no registered residential uses or occupational uses resulting in residential exposure 

associated with chlorimuron ethyl. Therefore, a quantitative residential exposure assessment was 

not performed.

6.1 Spray Drift

A detailed description about HED’s spray drift policy and how to evaluate the drift potential and 

associated risks is available in Appendix F.

6.1.1 Combined Risk Estimates from Lawn Deposition Adjacent to Applications

The spray drift risk estimates are based on an estimated deposited residue concentration as a 

result of the screening level agricultural application scenarios. The potential risk estimates from 

these residues can be calculated using drift modeling onto 50 feet wide lawns coupled with 

methods employed for residential risk assessments for turf products. Chlorimuron ethyl is used 

on a variety of agricultural crops including soybeans, field corn, peanuts, and low growing 

berries (subgroup 13-07H, except strawberry). It is also used in non-crop areas such as fence 

rows and roadsides and can be applied via ground and aerial equipment. Soybean is the 

predominant agricultural usage, and therefore, it is considered representative of the registered 

uses. The recommended drift scenario screening level options are listed below:

• Groundboom applications are based on the AgDrift option for high boom height and 

using very fine to fine spray type using the 90th percentile results. 

• Aerial applications are based on the use of AgDrift Tier 1 aerial option for a fine to 

medium spray type and a series of other parameters which will be described in more detail 

below (e.g., wind vector assumed to be 10 mph in a downwind direction for entire 

application/drift event). 

• Airblast applications are based on the AgDrift option for Sparse (Young/Dormant) tree 

canopies.

The spray drift assessment is based on dermal and incidental oral exposures. The highest 

exposure resulted from drift following chlorimuron applications using aerial equipment for 

children 1 to <2 years old (margins of exposure (MOEs) ≥ 23,000, with a LOC =100). There are 

no risks of concern at the field’s edge (i.e., assuming a residential lawn is directly adjacent to a 
Page 15 of 46

field where agricultural crops are grown and treated with aerial, groundboom or airblast 

equipment). See Tables 6.1.1 and 6.1.2 for detailed results.

1 HED’s default assumption that 10% of the application is available for transfer on day 0 following the application and the 

residues dissipate at a rate of 10% each following day.

1 HED’s default assumption that 10% of the application is available for transfer on day 0 following the application and the 

residues dissipate at a rate of 10% each following day.

6.2 Residential Bystander Post-Application Inhalation Exposure

Volatilization of pesticides may be a source of post-application inhalation exposure to 

individuals nearby pesticide applications. The agency sought expert advice and input on issues 

related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act 

Scientific Advisory Panel (SAP) in December 2009, and received the SAP’s final report on 

March 2, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The 

agency has evaluated the SAP report and has developed a Volatilization Screening Tool and a 

subsequent Volatilization Screening Analysis.

4

 During Registration Review, the agency will use

this analysis to determine if data (i.e., flux studies, route-specific inhalation toxicological studies) 

or further analyses are required for chlorimuron ethyl.

 

4 Available at: http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219.

Table 6.1.1. Adult Risk Estimates (MOEs) Related to Dermal Exposure to Spray Drift from Chlorimuron ethyl.

Crop/Rate 

Group Spray Type/ Nozzle Configuration Appl. Rate (lb ai/A) TTR1

(ug/cm2) At Edge of the Field

Aerial Fine to Medium

0.08 0.008892

30,000

Groundboom High Boom Very fine to Fine 42,000

Airblast Sparse 54,000

Table 6.1.2. Children (1<2 years old) Risk Estimates (MOEs) Related to Dermal and Indirect Exposure to Spray Drift 

from Chlorimuron.

Crop/Rate 

Group Spray Type/ Nozzle Configuration Appl. Rate (lb ai/A) TTR1

(ug/cm2) At Edge of the Field

Dermal

Aerial Fine to Medium

0.08 0.008892

23,000

Groundboom High Boom Very fine to Fine 32,000

Airblast Sparse 42,000

Incidental Oral (Hand-to-Mouth)

Aerial Fine to Medium 0.08 0.008892 29,000

Groundboom High Boom Very fine to Fine 0.08 0.008892 40,000

Airblast Sparse 51,000
Page 16 of 46

7.0 Aggregate Exposure/Risk Characterization

The Food Quality Protection Act of 1996 directs EPA to assess aggregate exposure to pesticide 

chemical residues, including all anticipated dietary exposures and all other exposures for which 

there is reliable information. In the case of chlorimuron ethyl, aggregate exposure and risk 

estimates are equivalent to the dietary exposure and risk estimates in Section 5, above, and are 

below HED’s level of concern.

8.0 Cumulative Exposure/Risk Characterization

In 2015, EPA’s Office of Pesticide Programs released a guidance document entitled, Pesticide 

Cumulative Risk Assessment: Framework for Screening Analysis 

[http://www.epa.gov/oppfead1/cb/csb_page/updates/2015/framework-for-screeninganalysis.html]. This document provides guidance on how to screen groups of pesticides for 

cumulative evaluation using a two-step approach beginning with the evaluation of available 

toxicological information and if necessary, followed by a risk-based screening approach. This 

framework supplements the existing guidance documents for establishing common mechanism 

groups (CMGs)5and conducting cumulative risk assessments (CRA)6. The Agency has utilized 

this framework to evaluate the SUs of which orthosulfamuron is a member (J. D’Agostino; 

D428798; 9/9/15). Although the SUs share some chemical and toxicological characteristics, the 

toxicological database does not support a testable hypothesis for a common mechanism of action. 

No further mechanistic data are required and no further cumulative evaluation is necessary.

9.0 Occupational Exposure/Risk Characterization

9.1 Occupational Handler Exposure/Risk Estimates

Based on current labeling, types of equipment and techniques that can potentially be used, 

occupational handler exposure is expected from the registered uses. The quantitative 

exposure/risk assessment developed for occupational handlers is based on the scenarios listed in 

Table 9.1. Based on the use pattern (i.e., 1-2 applications per crop depending on rate) and 

agricultural practices, occupational exposure from the registered food uses is expected to be 

short-term (1-30 days) and intermediate-term (i.e., 1-6 months) in duration. Since the same 

endpoint and point of departure were selected for short- and intermediate-term durations, shortterm exposure and risk estimates are considered to be protective of intermediate-term exposure 

and risk. Long-term exposures (i.e., more than 6 months) are not anticipated.

Occupational Handler Exposure Data and Assumptions

A series of assumptions and exposure factors served as the basis for completing the occupational 

handler risk assessments. Each assumption and factor is detailed below on an individual basis.

 

5 Guidance For Identifying Pesticide Chemicals and Other Substances that have a Common Mechanism of Toxicity 

(USEPA, 1999)

6 Guidance on Cumulative Risk Assessment of Pesticide Chemicals That Have a Common Mechanism of Toxicity 

(USEPA, 2002)
Page 17 of 46

Application Rate: The maximum single application rates are listed in Table 3.2. Refer to section 

3.0 for a complete use pattern description.

Body Weight: The standard body weight for the general population (80 kg) was used for all 

inhalation exposure scenarios covered in this risk assessment because the endpoint selected was 

not developmental and/or based on fetal effects. However, since the dermal PODs is based on 

developmental and/or fetal effects, the body weight appropriate for dermal assessments is 69 kg. 

Absorption Factor: Since no inhalation absorption data are available, toxicity by the inhalation 

route is considered to be equivalent to the estimated toxicity by the oral route of exposure. An 

upper bound dermal absorption factor of 4.8% was determined for the exposure assessment 

based on a comparison between the dermal toxicity and the oral rabbit developmental toxicity 

studies using a ratio of the oral LOAEL and dermal NOAEL [i.e., (48/1000)*100].

Unit Exposures: It is the policy of HED to use the best available data to assess handler exposure. 

Sources of generic handler data, used as surrogate data in the absence of chemical-specific data, 

include PHED 1.1, and the AHETF database. Some of these data are proprietary (e.g., AHETF 

data), and subject to the data protection provisions of FIFRA. The standard values recommended 

for use in predicting handler exposure that are used in this assessment, known as “unit 

exposures”, are outlined in the “Occupational Pesticide Handler Unit Exposure Surrogate 

Reference Table7.” HED policy on use of surrogate data, including descriptions of the various 

sources, can be found at the Agency website8. 

Area Treated or Amount Handled: The inputs for area treated or amount handled were based on 

the Science Advisory Council for Exposure Policy 9.1: Standard Values for Daily Acres Treated 

in Agriculture (values are listed in Table 9.1). The acres treated for high acreage crops and 

orchard/vineyards were used as screening for the occupational assessment.

Risk Estimate Equations: The algorithms used to estimate non-cancer exposure and dose for 

occupational handlers can be found in Appendix C.

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimate

The exposure scenarios presented in Table 9.1 are considered protective of all existing uses. All 

occupational handler scenarios for the registered uses resulted in MOEs greater than 100 at 

baseline level of risk mitigation (i.e., baseline attire with no gloves or respirator) or engineering 

control for aerial applications (i.e., enclosed cockpits) and, therefore, are not of concern. The 

lowest MOE is 860 associated with dermal exposure during mixing/loading activities for a 

dispersible granule formulation being applied aerially over up to 1,200 acres9. All other MOEs 

were significantly higher, ranging from 2,300 to 1,900,000. The current labels for chlorimuron 

 

7 Available: http://www.epa.gov/opp00001/science/handler-exposure-table.pdf

8 Available: http://www.epa.gov/pesticides/science/handler-exposure-data.html

9 The MOE of 860 is based on an application rate of 0.08 lb ai/A which was identified during the initial phase of 

registration review; however, that rate does not appear on any currently registered labels for chlorimuron ethyl.
Page 18 of 46

don’t require enclosed cockpits for aerial applications; therefore, PRD should ensure that the 

registered labels state the need of enclosed cockpits for aerial equipment.

The Agency matches quantitative occupational exposure assessment with appropriate 

characterization of exposure potential. While HED presents quantitative risk estimates for human 

flaggers where appropriate, agricultural aviation has changed dramatically over the past two 

decades. According the 2012 National Agricultural Aviation Association (NAAA) survey of 

their membership, the use of Global Positioning System (GPS) technology for swath guidance in 

agricultural aviation has grown steadily from the mid 1990’s. Over the same time period, the use 

of human flaggers for aerial pesticide applications has decreased steadily from ~15% in the late 

1990’s to only 1% in the most recent (2012) NAAA survey. The Agency will continue to 

monitor all available information sources to best assess and characterize the exposure potential 

for human flaggers in agricultural aerial applications.

HED has no data to assess exposures to pilots using open cockpits. The only data available 

reflects exposure to pilots in enclosed cockpits. Therefore, risks to pilots are assessed using the 

engineering control (i.e., enclosed cockpits) and baseline attire (i.e., long-sleeve shirt, long pants, 

shoes, and socks); per the Agency’s Worker Protection Standard stipulations for engineering 

controls, pilots are not required to wear protective gloves for the duration of the application. 

With this level of protection, there are no risk estimates of concern for applicators.

Table 9.1. Short-term Handler Exposure and Risk Estimates for Chlorimuron.

Exposure Scenario Dermal 

Unit 

Exposure 

(ug/lb ai)

[Mitigation 

Level]ab

Inhalation 

Unit 

Exposure

(ug/lb ai)

[Mitigation 

Level]ab

Application 

Ratec

Area 

Treated or 

Amount 

Handledd

Dermal 

Dosee

(mg/kg/day

)

Dermal 

MOEf

Inhalation 

Doseg

(mg/kg/day)

Inhalation 

MOEh

Mixer/Loader

Dry Flowable 

(Dispersible 

Granule) for Aerial 

Application

227 8.96 0.063 lb 

ai/A

1,200 A 0.012 1,000 0.00846 1,100

0.080 lb 

ai/A

0.015 860 0.0108 830

Dry Flowable 

(Dispersible 

Granule) for 

Groundboom 

Application

227 8.96 0.063 lb 

ai/A

200 A 0.00199 6,500 0.00141 6,400

0.080 lb 

ai/A 0.00253 5,100 0.00179 5,000

Dry Flowable 

(Dispersible 

Granule) for 

Airblast 

Application

227 8.96 0.063 lb 

ai/A

40 A 0.000398 33,000 0.000283 32,000

Applicator

Sprays for Aerial 

Application

2.08

[Engineeri

ng 

Controls –

Enclosed 

Cockpit]

0.0049

[Engineering 

Controls –

Enclosed 

Cockpit]

0.063 lb 

ai/A

1,200 A 0.000109 120,000 0.00000463 1,900,000

0.080 lb 

ai/A

0.000139 94,000 0.00000588 1,500,000

Sprays for 

Groundboom 

Application

78.6 0.34 0.063 lb 

ai/A

200 A 0.000689 19,000 0.0000535 170,000

0.080 lb 

ai/A

0.000877 15,000 0.0000680 130,000
Page 19 of 46

Table 9.1. Short-term Handler Exposure and Risk Estimates for Chlorimuron.

Exposure Scenario Dermal 

Unit 

Exposure 

(ug/lb ai)

[Mitigation 

Level]ab

Inhalation 

Unit 

Exposure

(ug/lb ai)

[Mitigation 

Level]ab

Application 

Ratec

Area 

Treated or 

Amount 

Handledd

Dermal 

Dosee

(mg/kg/day

)

Dermal 

MOEf

Inhalation 

Doseg

(mg/kg/day)

Inhalation 

MOEh

Sprays for Airblast 

Application

1,770 4.71 0.063 lb 

ai/A

40 A 0.0031 4,200 0.0001490 60,000

Flagger

Sprays for Aerial 

Application

11 0.35 0.063 lb 

ai/A

350 A 0.000169 77,000 0.0000965 93,000

0.080 lb 

ai/A

0.000214 61,000 0.000123 73,000

Mixer/Loader/Applicator

M/L/A Dry 

Flowable 

(Dispersible 

Granule) for 

Mechanicallypressurized 

Handgun

1,300 3.9 0.0063 lb 

ai/gal

1,000 gal 0.0057 2,300 0.000308 29,000

M/L/A Dry 

Flowable 

(Dispersible 

Granule) for 

Backpack Sprayer

8,260 2.58 0.0063 lb 

ai/gal

40 gal 0.00145 9,000 0.00000813 1,100,000

M/L/A Dry 

Flowable 

(Dispersible 

Granule) for 

Manuallypressurized 

Handwand

29,000 1,100 0.0063 lb 

ai/gal

40 gal 0.00509 2,600 0.00346 2,600

a. Mitigation Level: “baseline” (i.e., single layer of clothing consisting of a long sleeved shirt, long pants, shoes plus socks, no 

gloves, and no respirator); “engineering controls for aerial applications” (i.e., enclosed cockpit).

b. Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (February, 2015).

c. Based on the maximum single application rates listed on registered labels (Table 3.2). A maximum rate of 0.08 lb ai/A was 

identified during the scoping phase of registration review, but that rate is not on any currently registered labels; it may be from a 

petitioned-for use that was not registered.

d. Based on the Science Advisory Council for Exposure Policy 9.1: Standard Values for Daily Acres Treated in Agriculture.

e. Dermal Dose (mg/kg/day) = [Rate x UE x 0.0001 x Dermal Absorption (4.8%) x Acres Treated or Amount Handled]/BW (69

kg). f. Dermal MOE = Dermal NOAEL (mg/kg/day)/ Dermal Dose (mg/kg/day). LOC=100.

g. Inhalation Dose (mg/kg/day) = [Rate x UE x 0.0001 x Acres Treated or Amount Handled]/BW (80 kg).

h. Inhalation MOE = Inhalation NOAEL (mg/kg/day)/ Inhalation Dose (mg/kg/day). LOC=100.

9.2 Occupational Post-application Exposure/Risk Estimates

HED uses the term post-application to describe exposures that occur when individuals are 

present in an environment that has been previously treated with a pesticide (also referred to as reentry exposure). Such exposures may occur when workers enter previously treated areas to 

perform job functions, including activities related to crop production, such as scouting for pests 

or harvesting. Post-application exposure levels vary over time and depend on such things as the 

type of activity, the nature of the crop or target that was treated, the type of pesticide application, 

and the chemical’s degradation properties. In addition, the timing of pesticide applications, 

relative to harvest activities, can greatly reduce the potential for post-application exposure.
Page 20 of 46

9.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates

There are multiple potential sources of post-application inhalation exposure to individuals 

performing post-application activities in previously treated fields. These potential sources 

include volatilization of pesticides and resuspension of dusts and/or particulates that contain 

pesticides. The agency sought expert advice and input on issues related to volatilization of 

pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel 

(SAP) in December 2009, and received the SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The agency has 

evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent 

Volatilization Screening Analysis (http://www.regulations.gov/#!docketDetail;D=EPA-HQOPP-2014-0219). During Registration Review, the agency will utilize this analysis to determine 

if data (i.e., flux studies, route-specific inhalation toxicological studies) or further analysis is 

required for chlorimuron.

In addition, the Agency is continuing to evaluate the available post-application inhalation 

exposure data generated by the Agricultural Reentry Task Force. Given these two efforts, the 

Agency will continue to identify the need for and, subsequently, the way to incorporate 

occupational post-application inhalation exposure into the agency's risk assessments.

Although a quantitative occupational post-application inhalation exposure assessment was not 

performed, an inhalation exposure assessment was performed for occupational handlers. Handler 

exposure resulting from application of pesticides outdoors is likely to result in higher exposure 

than post-application exposure. Therefore, it is expected that these handler inhalation exposure 

estimates would be protective of most occupational post-application inhalation exposure 

scenarios.

9.2.2 Occupational Post-application Dermal Exposure/Risk Estimates

A series of assumptions and exposure factors served as the basis for completing the occupational 

post-application dermal risk assessment, including the following:

Exposure Duration: Based on the use pattern and agricultural practices, occupational postapplication exposure from the registered food uses is expected to be short-term (1-30 days) and 

intermediate-term (i.e., 1-6 months) in duration. Since the same endpoint and point of departure 

were selected for short- and intermediate-term durations, short-term exposure and risk estimates 

are considered to be protective of intermediate-term exposure and risk. Long-term exposures 

(i.e., more than 6 months) are not anticipated.

Transfer Coefficients: It is the policy of HED to use the best available data to assess postapplication exposure. Sources of generic post-application data, used as surrogate data in the 

absence of chemical-specific data, are derived from Agricultural Re-entry Task Force (ARTF)

exposure monitoring studies, and, as proprietary data, are subject to the data protection 

provisions of FIFRA. The standard values recommended for use in predicting post-application 

exposure that are used in this assessment, known as “transfer coefficients”, are presented in the 
Page 21 of 46

ExpoSAC Policy 310” which, along with additional information about the ARTF data, can be 

found at the Agency website11. Table 9.2.2.1 provides a summary of the anticipated postapplication activities and associated transfer coefficients for the proposed crops/use sites.

Table 9.2.2.1. Anticipated High-contact Post-Application Activities and Dermal Transfer Coefficients.

Proposed Crops

Policy Crop 

Group 

Category

Crop 

Height

Foliage 

Density

Transfer 

Coefficients 

(cm2/hr)

Activities

Corn, sweet, grain, 

processing Field, row, tall High Full 1,900 Irrigation (Hand set)

Corn, sweet, grain Field, row, tall High Full 8,800 Hand, Detasseling

Cranberry Berry, low Low Full 1,100 Scouting

Peanuts Field, row, 

low-medium Low Full 1,900 Irrigation (Hand set)

Soybean Field, row, 

low-medium Low Full 1,100 Scouting

Application Rate: The maximum single application rates are listed in Table 3.2. Refer to section 

3.0 for a complete use pattern description.

Exposure Time: The average occupational workday is assumed to be 8 hours. 

Dislodgeable Foliar Residues: Chemical-specific dislodgeable foliar residue data have not been 

submitted for chlorimuron during registration review. This assessment uses HED’s default 

assumption that 25% of the application is available for transfer on day 0 following the 

application and the residues dissipate at a rate of 10% each following day.

Risk Estimate Equations: The algorithms used to estimate non-cancer exposure and dose for 

occupational post-application workers can be found in Appendix C.

Occupational Post-application Non-Cancer Dermal Risk Estimates

A summary of the post-application exposure and risk estimates for the registered uses is provided 

in Table 9.2.2.2. Only risk estimates for the highest contact activity for each crop are shown 

below. Post-application dermal exposure and risk estimates for the scenarios shown below 

resulted in MOEs greater than 100 and are not of concern on day 0 (i.e., 12 hours following 

application). All other scenarios involving lower contact activities would have higher MOEs and 

are also not of concern.

 

10 Available: http://www.epa.gov/pesticides/science/exposac_policy3.pdf

11 Available: http://www.epa.gov/pesticides/science/post-app-exposure-data.html
Page 22 of 46

Table 9.2.2.2. Occupational Post-application Non-Cancer Exposure and Risk Estimates for Chlorimuron.

Crop/Site Activities Transfer Coefficient 

(cm2/hr) DFR1 Dermal Dose (mg/kg/day)2 MOE3

Short- and Intermediate-term

Corn, sweet, grain, 

processing

Irrigation (Hand 

set) 1,900 0.18 0.00187 7,000

Corn, sweet, grain Hand, Detasseling 8,800 0.18 0.00865 1,500

Cranberry Scouting 1,100 0.04 0.00027 47,000

Peanuts Irrigation (Hand 

set) 1,900 0.09 0.0092 14,000

Soybean Scouting 1,100 0.22 0.00137 9,500

1. DFR = Application Rate × F × (1-D)t × 4.54E8 μg/lb × 2.47E-8 acre/cm2; where F = 0.25 and D = 0.10 per day.

2. Daily Dermal Dose = [DFR (μg/cm2) × Transfer Coefficient × 0.001 mg/μg × 8 hrs/day × Dermal Absorption (%)]  BW (kg).

3. MOE = Dermal NOAEL (mg/kg/day) / Dermal Dose (mg/kg/day); LOC=100. 

Restricted Entry Interval

The REI specified on the proposed label is based on the acute toxicity of chlorimuron. 

Chlorimuron is classified as Toxicity Category III via the dermal route and Toxicity Category IV 

for skin irritation potential. It is not a skin sensitizer. Short- and intermediate-term postapplication risk estimates were not a concern on day 0 (i.e., 12 hours following application) for 

all post-application activities. Under 40 CFR 156.208 (c) (2) (iii), ai’s classified as Acute III or 

IV for acute dermal, eye irritation and primary skin irritation are assigned a 12-hour REI. 

Therefore, the [156 subpart K] Worker Protection Statement interim REI of 12 hours is adequate 

to protect agricultural workers from post-application exposures to chlorimuron.

10.0 Public Health and Pesticide Epidemiology Data

D426223, S. Recore, 12 May 2015

Chlorimuron-ethyl was previously reviewed in 2010 (K. Middleton et al., 08/19/2010, D380339). 

At the time, there were no incidents reported for the single chemical chlorimuron ethyl in the Main

Incident Data System (IDS) and three incidents reported to Aggregate IDS from January 1, 2000 

to May 25, 2010. In addition, there were two cases reported for chlorimuron ethyl to NIOSH 

SENSOR-Pesticides from 1998 to 2007. Upon review of these incidents, it was concluded that 

“Based on the low frequency and severity of incident cases, there does not appear to be a concern 

at this time that would warrant further investigation.” 

The current IDS analysis from January 1, 2010 through March 10, 2015, shows one incident 

reported involving chlorimuron ethyl in Main IDS involving multiple chemicals and six incidents 

reported to Aggregate IDS. There were no single-chemical incidents reported to IDS. The query 

of SENSOR-Pesticides 1998-2011 identifies the same two cases, both involving multiple active 

ingredients, that were previously identified in 2010. 

Based on the low frequency and mostly low severity of incident cases reported for chlorimuron 

ethyl in both IDS and NIOSH SENSOR-Pesticides, there does not appear to be a concern at this 
Page 23 of 46

time that would warrant further investigation. Several initial investigations within the AHS have 

made an epidemiological risk estimate of the association between chlorimuron ethyl and various 

anatomical cancer endpoints; however, these cancer sites were either not related to use of 

chlorimuron ethyl (prostate or lung cancers, NHL, and cutaneous melanoma), or the association 

measured was non-statistically significantly modest in size (<1.5) (breast, colorectal, pancreatic 

cancers). The Agency will continue to monitor the incident information and if a concern is 

triggered, additional analysis will be conducted.

11.0 Literature References

A literature search was performed for chlorimuron ethyl. The search did not reveal information 

that would impact the current risk assessment. 

12.0 References

Author Barcode Date Title

Dow, M. D365816 24 June 2009 Chlorimuron ethyl: Human Occupational Exposure/Risk 

Assessment for the Proposed Use on Field Corn and 

Soybeans.

Cutchin, W. D358796 14 Sept 2009 Chlorimuron ethyl: Human Health Risk Assessment for 

Proposed Uses on Field Corn and Soybean.

Middleton, K. D380339 19 Aug 2010 Chlorimuron ethyl: Review of Human Incidents.

McNeilly, D. D379636 27 Sept 2010 Chlorimuron ethyl. Human Health Assessment Scoping 

Document in Support of Registration Review.

Recore, S., 

Evans, E., 

Christensen, C.

D426223 12 May 2015 Chlorimuron-ethyl: Tier I Review of Human Incidents for 

Draft Risk Assessment

G. Orrick D427429 8/12/2015 Drinking Water Exposure Assessment for the Registration 

Review of 22 Sulfonylurea Herbicides 
Page 24 of 46

Appendix A. Toxicology Data Requirements and Toxicology Profile 

The toxicology requirements (40 CFR 158.340) for chlorimuron ethyl are presented below. 

Test Technical

Required Satisfied

870.1100 Acute Oral Toxicity.......................................................

870.1200 Acute Dermal Toxicity..................................................

870.1300 Acute Inhalation Toxicity..............................................

870.2400 Primary Eye Irritation....................................................

870.2500 Primary Dermal Irritation..............................................

870.2600 Dermal Sensitization .....................................................

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

870.3100 Oral Subchronic (rodent)...............................................

870.3150 Oral Subchronic (nonrodent).........................................

870.3200 21-Day Dermal..............................................................

870.3250 90-Day Dermal..............................................................

870.3465 21/90-Day Inhalation.....................................................

Yes

Yes

Yes

No

No

Yes

Yes

No

No

Not required*

870.3700a Developmental Toxicity (rodent) ..................................

870.3700b Developmental Toxicity (nonrodent) ............................

870.3800 Reproduction .................................................................

Yes

Yes

Yes

Yes

Yes

Yes

870.4100a Chronic Toxicity (rodent)..............................................

870.4100b Chronic Toxicity (nonrodent)........................................

870.4200a Oncogenicity (rat)..........................................................

870.4200b Oncogenicity (mouse) ...................................................

870.4300 Chronic/Oncogenicity ...................................................

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

870.5100 Mutagenicity—Gene Mutation - bacterial.....................

870.5300 Mutagenicity—Gene Mutation - mammalian ...............

870.5385 Mutagenicity—Mammalian Bone Marrow 

 Chromosome Aberration Aberrations ....

870.5550 Mutagenicity—Unscheduled DNA Synthesis...............

Yes

Yes

Yes

No

Yes

Yes

Yes

No

870.6200a Acute Neurotoxicity Screening Battery (rat).................

870.6200b 90-Day Neurotoxicity Screening Battery (rat) ..............

870.6300 Developmental Neurotoxicity .......................................

Yes

Yes

No

Yes

Yes

No

870.7485 General Metabolism......................................................

870.7600 Dermal Penetration........................................................

870.7800 Immunotoxicity .............................................................

Yes

No

Yes

Yes

No

Not required*

* The Hazard and Science Policy Council (HASPOC) determined that subchronic inhalation and immunotoxicity studies are not 

required (TXR#s 0056401 and 0056723).
Page 25 of 46

A.2. Toxicity Profiles

Table A.1. Acute Toxicity Profile – Chlorimuron ethyl 

Type of 

Study/Guide 

line

Study Title MRID Results

870.1000 Acute Oral LD50, Rat (75%) 00131566 LD50 (M/F) >5000 mg/kg

Tox Category IV

870.1200 Acute Dermal LD50, Rabbit (75%) 00131567 LD50 (M/F) >2000 mg/kg

Tox Category III

870.1300 Acute Inhalation Toxicity, Rats (96%) 40843203 LC50 (M/F) 5 mg/L

Tox Category IV

870.2400 Primary Eye Irritation, Rabbit

(75%)

00131568 mild irritation @ 26 mg

Tox Category III

870.2500 Primary Dermal Irritation, Rabbit (75%) 00131569 mild erythema and edema @ 0.5 g

Tox Category IV

870.2600 Dermal Sensitization, Guinea Pig (75%) 00131570 Not a sensitizer

Table A.2. Subchronic, Chronic and Other Toxicity Profile for Chlorimuron ethyl 

Guide line Study Title MRID Dose Levels Results

870.3100 90-Day Oral Toxicity, 

Rat

MRID 00131581 Levels tested: 0, 

100, 2500, 7500 

ppm, equivalent 

to:

[M]: 0, 7, 173, 

551 mg/kg/day

[F]: 0, 8, 209, 

672 mg/kg/day

NOAEL (M/F) = 7/8 mg/kg/day (100 

ppm)

LOAEL (M/F) = 173/209 mg/kg/day 

(2500 ppm) based on decreased body 

weight gain (14%) in females and liver 

pathology (margination of hepatocyte 

cytoplasmic content in centrilobular 

areas) in males

a870.3100 90-Day Oral Toxicity, 

Mouse

MRID 00143127 Levels tested: 0, 

25, 125, 1250, 

5000 ppm 

equivalent to: 

[M]: 0, 6, 27, 

268, 1030 

mg/kg/day

[F]: 0, 6, 30, 

381, 

1151mg/kg/day

NOAEL (M/F) 1030/1151 mg/kg/day

LOAEL not established

870.3150 90-Day Oral Toxicity, 

Dog

MRID 00132745 Levels tested: 0, 

100, 1500, 7500 

ppm equivalent 

to:

[M]: 0, 2.8, 

45.8, 176.5 

mg/kg/day

[F]: 0, 2.9, 42.7, 

187.1 

mg/kg/day

NOAEL (M/F) = 2.8/2.9 mg/kg/day (100 

ppm)

LOAEL (M/F) = 45.8/42.7 mg/kg/day 

(1500 ppm), based on hematologic 

changes (increased hematocrit, 

hemoglobin, erythrocyte counts in mid 

and high dose dogs) atrophy of thymus 

and prostate, increased absolute and 

relative liver weights.

870.3200 21-Day Dermal, 

Rabbit

MRID 4864620 Levels tested: 0, 

100, 400, 1000

NOAEL=1000 mg/kg/day

LOAEL=not determined

870.3465 21/90-Day Inhalation Not required
Page 26 of 46

Table A.2. Subchronic, Chronic and Other Toxicity Profile for Chlorimuron ethyl 

Guide line Study Title MRID Dose Levels Results

870.4100b Chronic Feeding, Dog MRID 00149579 Levels tested: 0, 

25, 250, 1500 

ppm, equivalent 

to: [M]: 0, 0.8, 

10, 51 

mg/kg/day

[F]: 0, 0.8, 9, 55 

mg/kg/day

NOAEL = 10/9 mg/kg/day (250 ppm)

LOAEL = 51/55 mg/kg/day (1500 ppm), 

based on mild decrease in erythrocyte 

count, hematocrit, and hemoglobin 

concentration (mild anemia)

870.4200b Carcinogenicity, 18-

Month Feeding, 

Mouse

MRID 00145781 Levels tested: 0, 

12.5, 125, 1250 

ppm equivalent 

to:

[M]: 0, 1.6, 16, 

160 mg/kg/day,

[F]: 0, 2.1, 21, 

216 mg/kg/day

NOAEL (M/F) 160/216 mg/kg/day 

LOAEL not established

No treatment-related neoplasms

870.4300 Chronic/Oncogenicity, 

2- Year-Rat

MRID 00149580 Levels tested: 0, 

25, 250, 2500 

ppm equivalent 

to: 

[M&F]: 0, 1.25, 

12.5, 125 

mg/kg/day

NOAEL = 12.5 mg/kg/day (250 ppm)

LOAEL= 125 mg/kg/day) (2500 ppm) 

based on decreased body weight in both 

sexes (8/24% [M/F], respectively)

No treatment-related neoplasms

870.3700a Developmental 

Toxicity, Rat

MRID 00131582 Levels tested: 0, 

30, 150, 600 

mg/kg/day GD 

7-16

Maternal NOAEL = 30 mg/kg/day

Maternal LOAEL = 150 mg/kg/day 

based on decreased weight gain during 

GD 7-16 (11%)

Developmental NOAEL = 30 mg/kg/day

Developmental LOAEL = 150 

mg/kg/day based on growth retardation 

(delayed ossification, centra and 

sternebrae)

870.3700b Developmental 

Toxicity, Rabbit

MRID 00145782 Levels tested: 0, 

13, 48, 300 

mg/kg/day GD 

7-19

Maternal NOAEL = 48 mg/kg/day

Maternal LOAEL = 300 mg/kg/day 

based on decreased weight gain during 

DG 7-19 (5%)

Developmental NOAEL = 13 mg/kg/day

Developmental LOAEL = 48 mg/kg/day 

based on delayed ossification

870.3800 Reproduction (1-

Generation), Rat

MRID 00131581 Levels tested: 0, 

100, 2500, 7500 

ppm equivalent 

to: [M]: 0, 7, 

173, 

551mg/kg/day

[F]: 0, 8, 209, 

672 mg/kg/day

Reproductive NOAEL (M/F) = 

>551/672 mg/kg/day

Reproductive LOAEL (M/F) = not 

established

Offspring NOAEL = 7/8 mg/kg/day

Offspring LOAEL = 173/209 mg/kg/day 

based on decreased litter weights

Parental NOAEL (M/F) = 7/8 

mg/kg/day

Parental LOAEL (M/F) 

=173/209( mg/kg/day) based on 
Page 27 of 46

Table A.2. Subchronic, Chronic and Other Toxicity Profile for Chlorimuron ethyl 

Guide line Study Title MRID Dose Levels Results

decreased body weight in females (12%) 

and liver pathology in males

870.3800 Reproduction (1-year 

interim sacrifice), Rat

MRID 00143128 Levels tested: 0, 

25, 250, 2500 

ppm equivalent 

to:

[M]: 0, ?, 19, 

195 mg/kg/day

[F]: 0, ?, 23, 

227 mg/kg/day

Reproductive NOAEL 195/227 

mg/kg/day

Reproductive LOAEL not established

Offspring NOAEL = 19/23 mg/kg/day

Offspring LOAEL = 195/227 mg/kg/day 

based on decreased pup weight (20% 

and 19% in F1a M and F, respectively; 

12% in F1b F)

Parental NOAEL = 19/23 mg/kg/day

Parental LOAEL = 195/227 mg/kg/day 

based on decreased body weight (12% 

F)

870.3800 Reproduction (2-

Generation), Rat

MRID 00149580 Levels tested: 0, 

25, 250, 2500 

ppm equivalent 

to: 

[M]: 0, 1.7, 17, 

177 mg/kg/day

[F]: 0, 2.2, 21, 

214 mg/kg/day

Reproductive NOAEL 177/214 

mg/kg/day

Reproductive LOAEL = not established

Offspring NOAEL = 17/21mg/kg/day

Offspring LOAEL = 177/214 mg/kg/day 

based on reduced pup weight (20/19% in 

F1a M/F; 7/12% in F1b M/F; 13/13% in 

F2a M/F; 20/18% in F2b M/F ) and 

histopathologic findings in the 

cerebellum (cellular changes in the 

internal granular and external germinal 

layers)

Parental NOAEL (M/F) 177/214 

mg/kg/day

Parental LOAEL not established

870.5100 Ames Bacterial 

Mutagenicity Test

MRID 00131571 --- Negative at 0.001 through 0.5 ·g/ml in 

presence of rat liver S-9 activation.

870.5300 In Vitro Mammalian 

Gene Mutation -

Chinese Hamster 

Ovary BH4 Cells

MRID 00131572 --- Not mutagenic in the presence or 

absence of S-9 activation

870.5385 Mammalian Bone 

Marrow Chromosome 

Aberration Assay -

Rat

MRID 00131573 --- This study was negative for induction of 

chromosome aberrations in the bone 

marrow cells of male or female SpragueDawley rats 6-, 12-, 24-, and 48- hr time 

points after gavage administration of 

500-1500 mg/kg of test material 

870.5550 Unscheduled DNA 

Synthesis

MRID 00132577

00155156

--- Additional data supporting a justification 

for the selection of the highest dose level 

was submitted and accepted. Based on 

these findings, it was concluded that 

chlorimuron ethyl showed no evidence 

of UDS.

870.6200a Acute neurotoxicity 

screening battery-rats

MRID

48704302

Levels tested: 

mg/kg/day 

(M/F): 0, 100, 

500, 2000

NOAEL = 100 mg/kg/day

LOAEL = 500 mg/kg/day, based on 

reduced arousal and reduced motor 

activity
Page 28 of 46

Table A.2. Subchronic, Chronic and Other Toxicity Profile for Chlorimuron ethyl 

Guide line Study Title MRID Dose Levels Results

870.6200b Subchronic 

neurotoxicity 

screening battery

MRID 48704301 Levels tested: 

ppm: 0, 500, 

1,250, and 

3,750/5,000 

(equivalent to 

mg/kg/day 

(M/F): 0/0, 

27/35, 71/90, 

and 220/259 

NOAEL = 71 mg/kg/day

LOAEL = 220 mg/kg/day, based on 

decreased body weight and body weight 

gains and reduced food consumption in 

females. 

870.7485 General Metabolism MRIDs 

00154749 and 

00149578

Doses = 16 and 

3000 mg/kg of 

14C labeled 

phenyl or 

pyrimidinyl 

rings of 

chlorimuron 

ethyl. 

Chlorimuron ethyl extensively 

metabolized by both male and female 

rats at the low and high dose. Excretion 

was monitored up to 168 hrs. 

Elimination of radioactivity was equally 

via the urine & feces for low and high

dose. Half-life = 50 hrs. Major 

metabolites: HOPY-DPX-F6025, ODMDPX-F6025, HPY-DPX-F6025, DIHOPY- DPX-F6025, DPX-F6025 (See 

Appendix V for structures).

870.7800 Immunotoxicity Not required
Page 29 of 46

Appendix B. Review of Human Research

This risk assessment relies in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These data are subject to ethics review 

pursuant to 40 CFR 26, have received that review, and are compliant with applicable ethics 

requirements. For certain studies that review may have included review by the Human Studies 

Review Board. Descriptions of data sources as well as guidance on their use can be found at:

http://www.epa.gov/pesticides/science/handler-exposure-data.html and 

http://www.epa.gov/pesticides/science/post-app-exposure-data.html.

Appendix C. Occupational Non-cancer Algorithms

Occupational Non-cancer Handler Algorithms

Potential daily exposures for occupational handlers are calculated using the following formula:

E=UE * AR * A * 0.001 mg/ug

where:

E = exposure (mg ai/day),

UE = unit exposure (μg ai/lb ai),

AR = maximum application rate according to registered labels (lb ai/A), and

A = area treated or amount handled (e.g., A/day or gal/day).

The daily doses are calculated using the following formula:

ADD= 

E * AF

BW

where:

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day),

E = exposure (mg ai/day),

AF = absorption factor (dermal or inhalation), and

BW = body weight (kg).

Margin of Exposure: Non-cancer risk estimates for each application handler scenario are 

calculated using a Margin of Exposure (MOE), which is a ratio of the toxicological endpoint to 

the daily dose of concern. The daily dermal and/or inhalation doses received by occupational 

handlers are compared to the appropriate POD (i.e., NOAEL) to assess the risk to occupational 

handlers for each exposure route. All MOE values are calculated using the following formula:

MOE= 

POD

ADD

where:

MOE = margin of exposure: value used by HED to represent risk estimates (unitless),

POD = point of departure (mg/kg/day), and

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day).

Occupational Non-cancer Post-application Algorithms
Page 30 of 46

Potential daily exposures for occupational post-application workers are calculated using the 

following formulas:

DFRt=AR * F* (1-D)t* (4.54E8

ug

lb) * (2.47E-8

A

cm2

)

where:

DFRt = dislodgeable foliage residue on day "t" (μg/cm2),

AR = application rate (lb ai/acre),

F = fraction of ai retained on foliage or 25% (unitless),

D = fraction of residue that dissipates daily or 10% (unitless), and

t = number of days after application day (days).

E=TC * DFR t* ET * 0.001

mg

ug

where:

E = exposure (mg ai/day),

TC = transfer coefficient (cm2/hr),

DFRt = dislodgeable foliar residue on day “t” (μg/cm2), and

ET = exposure time (hours/day).

The daily doses are calculated using the following formula:

ADD= 

E * AF

BW

where:

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day),

E = exposure (mg ai/day),

AF = absorption factor (dermal), and

BW = body weight (kg).

Margin of Exposure: Non-cancer risk estimates for each scenario are calculated using a Margin 

of Exposure (MOE), which is a ratio of the toxicological endpoint to the daily dose of concern. 

The daily dermal dose received by occupational post-application workers is compared to the 

appropriate POD (i.e., NOAEL) to assess the risk to occupational post-application workers. All 

MOE values are calculated using the following formula:

MOE= 

POD

ADD

where:

MOE = margin of exposure: value used by HED to represent risk estimates (unitless),

POD = point of departure (mg/kg/day), and

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day).
Page 31 of 46

Appendix D. Dietary Exposure/Risk Modeling Input and Output

Filename: Chlorimuron.R08

Chemical: Chlorimuron

RfD(Chronic): .09 mg/kg bw/day NOEL(Chronic): 0 mg/kg bw/day

RfD(Acute): 1 mg/kg bw/day NOEL(Acute): 0 mg/kg bw/day

Date created/last modified: 04-08-2015/11:58:43 Program ver. 3.16, 03-08-d

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

 EPA Crop Def Res Adj.Factors Comment

 Code Grp Commodity Name (ppm) #1 #2 

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

0600347000 6 Soybean, seed 0.050000 1.000 1.000 

0600349000 6 Soybean, soy milk 0.050000 1.000 1.000 

0600349001 6 Soybean, soy milk-babyfood or in 0.050000 1.000 1.000 

0600350000 6 Soybean, oil 0.050000 1.000 1.000 

0600350001 6 Soybean, oil-babyfood 0.050000 1.000 1.000 

0603348000 6C Soybean, flour 0.050000 1.000 1.000 

0603348001 6C Soybean, flour-babyfood 0.050000 1.000 1.000 

1302057000 13B Blueberry 0.020000 1.000 1.000 

1302057001 13B Blueberry-babyfood 0.020000 1.000 1.000 

1307130000 13G Cranberry 0.020000 1.000 1.000 

1307130001 13G Cranberry-babyfood 0.020000 1.000 1.000 

1500120000 15 Corn, field, flour 0.010000 1.000 1.000 

1500120001 15 Corn, field, flour-babyfood 0.010000 1.000 1.000 

1500121000 15 Corn, field, meal 0.010000 1.000 1.000 

1500121001 15 Corn, field, meal-babyfood 0.010000 1.000 1.000 

1500122000 15 Corn, field, bran 0.010000 1.000 1.000 

1500123000 15 Corn, field, starch 0.010000 1.000 1.000 

1500123001 15 Corn, field, starch-babyfood 0.010000 1.000 1.000 

1500124000 15 Corn, field, syrup 0.010000 1.000 1.000 

1500124001 15 Corn, field, syrup-babyfood 0.010000 1.000 1.000 

1500125000 15 Corn, field, oil 0.010000 1.000 1.000 

1500125001 15 Corn, field, oil-babyfood 0.010000 1.000 1.000 

8601000000 86A Water, direct, all sources 0.751000 1.000 0.655 Fact. 2 = 492 / 751 

(chronic/acute H2O)

8602000000 86B Water, indirect, all sources 0.751000 1.000 0.655 Fact. 2 = 492 / 751 

(chronic/acute H2O)

9500263000 O Peanut 0.020000 1.000 1.000 

9500264000 O Peanut, butter 0.020000 1.000 1.000 

9500265000 O Peanut, oil 0.020000 1.000 1.000 
Page 32 of 46

US EPA Ver. 3.16, 03-08-d

DEEM-FCID Chronic analysis for CHLORIMURON NHANES 2003-2008 2-day

Residue file name: Chlorimuron.R08

 Adjustment factor #2 used.

Analysis Date 04-08-2015/11:46:01 Residue file dated: 04-08-2015/11:12:22

Reference dose (RfD, Chronic) = .09 mg/kg bw/day

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

 Total exposure by population subgroup

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

 Total Exposure

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

 Population mg/kg Percent of 

 Subgroup body wt/day Rfd 

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

Total US Population 0.010345 11.5%

Hispanic 0.009883 11.0%

Non-Hisp-White 0.010637 11.8%

Non-Hisp-Black 0.008543 9.5%

Non-Hisp-Other 0.011925 13.2%

Nursing Infants 0.009351 10.4%

Non-Nursing Infants 0.034382 38.2%

Female 13+ PREG 0.009738 10.8%

Children 1-6 0.013302 14.8%

Children 7-12 0.008652 9.6%

Male 13-19 0.007127 7.9%

Female 13-19/NP 0.007975 8.9%

Male 20+ 0.009631 10.7%

Female 20+/NP 0.010851 12.1%

Seniors 55+ 0.009988 11.1%

All Infants 0.026654 29.6%

Female 13-50 0.010286 11.4%

Children 1-2 0.014977 16.6%

Children 3-5 0.012624 14.0%

Children 6-12 0.009099 10.1%

Youth 13-19 0.007555 8.4%

Adults 20-49 0.010313 11.5%

Adults 50-99 0.010190 11.3%

Female 13-49 0.010275 11.4%

-------------------------------------------------------------------------------
Page 33 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Summary calculations--per capita:

 95th Percentile 99th Percentile 99.9th Percentile

Exposure % aRfD Exposure % aRfD Exposure % aRfD 

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

Total US Population:

 0.040989 4.10 0.067488 6.75 0.128489 12.85 

All Infants:

 0.128345 12.83 0.173678 17.37 0.256576 25.66 

Children 1-2:

 0.063275 6.33 0.095464 9.55 0.235102 23.51 

Children 3-5:

 0.051309 5.13 0.079153 7.92 0.125941 12.59 

Children 6-12:

 0.039140 3.91 0.064122 6.41 0.098832 9.88 

Youth 13-19:

 0.034153 3.42 0.056287 5.63 0.085017 8.50 

Adults 20-49:

 0.040398 4.04 0.059937 5.99 0.087504 8.75 

Adults 50-99:

 0.035994 3.60 0.054352 5.44 0.085668 8.57 

Female 13-49:

 0.040893 4.09 0.060056 6.01 0.084457 8.45 
Page 34 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Summary calculations--users:

 95th Percentile 99th Percentile 99.9th Percentile

Exposure % aRfD Exposure % aRfD Exposure % aRfD 

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

Total US Population:

 0.041007 4.10 0.067515 6.75 0.128531 12.85 

All Infants:

 0.131773 13.18 0.189910 18.99 0.256753 25.68 

Children 1-2:

 0.063290 6.33 0.095466 9.55 0.235105 23.51 

Children 3-5:

 0.051309 5.13 0.079153 7.92 0.125941 12.59 

Children 6-12:

 0.039141 3.91 0.064123 6.41 0.098832 9.88 

Youth 13-19:

 0.034159 3.42 0.056289 5.63 0.085017 8.50 

Adults 20-49:

 0.040400 4.04 0.059938 5.99 0.087506 8.75 

Adults 50-99:

 0.035998 3.60 0.054354 5.44 0.085669 8.57 

Female 13-49:

 0.040893 4.09 0.060056 6.01 0.084457 8.45 
Page 35 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

Acute Reference Dose (aRfD) = 1.000000 mg/kg body-wt/day

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Total US Population Daily Exposure Analysis /a

------------------- (mg/kg body-weight/day) 

 per Capita per User 

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

 Mean 0.015769 0.015794

 Standard Deviation 0.014375 0.014373

 Standard Error of mean 0.000065 0.000065

 Percent of aRfD 1.58 1.58

 Percent of Person-Days that are User-Days = 99.84%

 Estimated percentile of user-days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.002419 0.24 90.00 0.031618 3.16

 20.00 0.005195 0.52 95.00 0.041007 4.10

 30.00 0.007609 0.76 97.50 0.051801 5.18

 40.00 0.009994 1.00 99.00 0.067515 6.75

 50.00 0.012599 1.26 99.50 0.082328 8.23

 60.00 0.015549 1.55 99.75 0.097503 9.75

 70.00 0.018959 1.90 99.90 0.128531 12.85

 80.00 0.023468 2.35

 Estimated percentile of per-capita days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.002367 0.24 90.00 0.031599 3.16

 20.00 0.005162 0.52 95.00 0.040989 4.10

 30.00 0.007579 0.76 97.50 0.051773 5.18

 40.00 0.009971 1.00 99.00 0.067488 6.75

 50.00 0.012576 1.26 99.50 0.082279 8.23

 60.00 0.015529 1.55 99.75 0.097471 9.75

 70.00 0.018941 1.89 99.90 0.128489 12.85

 80.00 0.023449 2.34

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

a/ Analysis based on all two-day participant records in NHANES 2003-2008 2-Day

 with 2 days of valid drinking water records.
Page 36 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

Acute Reference Dose (aRfD) = 1.000000 mg/kg body-wt/day

RAC/FF intake summed over 24 hours

Run Comment: ""

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

All Infants Daily Exposure Analysis 

----------- (mg/kg body-weight/day) 

 per Capita per User 

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

 Mean 0.040651 0.044814

 Standard Deviation 0.045130 0.045374

 Standard Error of mean 0.000903 0.000949

 Percent of aRfD 4.07 4.48

 Percent of Person-Days that are User-Days = 90.71%

 Estimated percentile of user-days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.000261 0.03 90.00 0.106724 10.67

 20.00 0.002380 0.24 95.00 0.131773 13.18

 30.00 0.007809 0.78 97.50 0.148414 14.84

 40.00 0.016893 1.69 99.00 0.189910 18.99

 50.00 0.031183 3.12 99.50 0.200542 20.05

 60.00 0.050135 5.01 99.75 0.233871 23.39

 70.00 0.065966 6.60 99.90 0.256753 25.68

 80.00 0.082569 8.26

 Estimated percentile of per-capita days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.000020 0.00 90.00 0.103662 10.37

 20.00 0.000308 0.03 95.00 0.128345 12.83

 30.00 0.004184 0.42 97.50 0.146126 14.61

 40.00 0.010654 1.07 99.00 0.173678 17.37

 50.00 0.022606 2.26 99.50 0.200028 20.00

 60.00 0.043150 4.31 99.75 0.231885 23.19

 70.00 0.062864 6.29 99.90 0.256576 25.66

 80.00 0.078732 7.87
Page 37 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

Acute Reference Dose (aRfD) = 1.000000 mg/kg body-wt/day

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Children 1-2 Daily Exposure Analysis 

------------ (mg/kg body-weight/day) 

 per Capita per User 

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

 Mean 0.022810 0.022819

 Standard Deviation 0.022327 0.022327

 Standard Error of mean 0.000408 0.000408

 Percent of aRfD 2.28 2.28

 Percent of Person-Days that are User-Days = 99.96%

 Estimated percentile of user-days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.002319 0.23 90.00 0.048759 4.88

 20.00 0.006346 0.63 95.00 0.063290 6.33

 30.00 0.010007 1.00 97.50 0.078475 7.85

 40.00 0.013597 1.36 99.00 0.095466 9.55

 50.00 0.017206 1.72 99.50 0.132912 13.29

 60.00 0.021318 2.13 99.75 0.145762 14.58

 70.00 0.026843 2.68 99.90 0.235105 23.51

 80.00 0.035296 3.53

 Estimated percentile of per-capita days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.002296 0.23 90.00 0.048755 4.88

 20.00 0.006338 0.63 95.00 0.063275 6.33

 30.00 0.010001 1.00 97.50 0.078466 7.85

 40.00 0.013588 1.36 99.00 0.095464 9.55

 50.00 0.017200 1.72 99.50 0.132911 13.29

 60.00 0.021309 2.13 99.75 0.145750 14.57

 70.00 0.026833 2.68 99.90 0.235102 23.51

 80.00 0.035288 3.53
Page 38 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

Acute Reference Dose (aRfD) = 1.000000 mg/kg body-wt/day

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Children 3-5 Daily Exposure Analysis 

------------ (mg/kg body-weight/day) 

 per Capita per User 

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

 Mean 0.019209 0.019209

 Standard Deviation 0.017378 0.017378

 Standard Error of mean 0.000327 0.000327

 Percent of aRfD 1.92 1.92

 Percent of Person-Days that are User-Days = 100.00%

 Estimated percentile of user-days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.001778 0.18 90.00 0.040676 4.07

 20.00 0.005999 0.60 95.00 0.051309 5.13

 30.00 0.008983 0.90 97.50 0.062160 6.22

 40.00 0.011962 1.20 99.00 0.079153 7.92

 50.00 0.015315 1.53 99.50 0.093587 9.36

 60.00 0.018874 1.89 99.75 0.103124 10.31

 70.00 0.023074 2.31 99.90 0.125941 12.59

 80.00 0.029466 2.95

 Estimated percentile of per-capita days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.001778 0.18 90.00 0.040676 4.07

 20.00 0.005999 0.60 95.00 0.051309 5.13

 30.00 0.008983 0.90 97.50 0.062160 6.22

 40.00 0.011962 1.20 99.00 0.079153 7.92

 50.00 0.015315 1.53 99.50 0.093587 9.36

 60.00 0.018874 1.89 99.75 0.103124 10.31

 70.00 0.023074 2.31 99.90 0.125941 12.59

 80.00 0.029466 2.95
Page 39 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

Acute Reference Dose (aRfD) = 1.000000 mg/kg body-wt/day

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Children 6-12 Daily Exposure Analysis 

------------- (mg/kg body-weight/day) 

 per Capita per User 

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

 Mean 0.013850 0.013851

 Standard Deviation 0.013186 0.013186

 Standard Error of mean 0.000163 0.000163

 Percent of aRfD 1.39 1.39

 Percent of Person-Days that are User-Days = 99.99%

 Estimated percentile of user-days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.001404 0.14 90.00 0.028689 2.87

 20.00 0.003889 0.39 95.00 0.039141 3.91

 30.00 0.005929 0.59 97.50 0.049490 4.95

 40.00 0.008161 0.82 99.00 0.064123 6.41

 50.00 0.010566 1.06 99.50 0.076224 7.62

 60.00 0.013359 1.34 99.75 0.086564 8.66

 70.00 0.016936 1.69 99.90 0.098832 9.88

 80.00 0.021420 2.14

 Estimated percentile of per-capita days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.001402 0.14 90.00 0.028689 2.87

 20.00 0.003888 0.39 95.00 0.039140 3.91

 30.00 0.005928 0.59 97.50 0.049489 4.95

 40.00 0.008160 0.82 99.00 0.064122 6.41

 50.00 0.010565 1.06 99.50 0.076224 7.62

 60.00 0.013358 1.34 99.75 0.086562 8.66

 70.00 0.016935 1.69 99.90 0.098832 9.88

 80.00 0.021420 2.14
Page 40 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

Acute Reference Dose (aRfD) = 1.000000 mg/kg body-wt/day

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Youth 13-19 Daily Exposure Analysis 

----------- (mg/kg body-weight/day) 

 per Capita per User 

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

 Mean 0.011511 0.011513

 Standard Deviation 0.011750 0.011750

 Standard Error of mean 0.000127 0.000127

 Percent of aRfD 1.15 1.15

 Percent of Person-Days that are User-Days = 99.98%

 Estimated percentile of user-days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.000452 0.05 90.00 0.025134 2.51

 20.00 0.002743 0.27 95.00 0.034159 3.42

 30.00 0.004584 0.46 97.50 0.044063 4.41

 40.00 0.006308 0.63 99.00 0.056289 5.63

 50.00 0.008263 0.83 99.50 0.067375 6.74

 60.00 0.010757 1.08 99.75 0.078791 7.88

 70.00 0.013672 1.37 99.90 0.085017 8.50

 80.00 0.017940 1.79

 Estimated percentile of per-capita days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.000448 0.04 90.00 0.025132 2.51

 20.00 0.002738 0.27 95.00 0.034153 3.42

 30.00 0.004581 0.46 97.50 0.044062 4.41

 40.00 0.006306 0.63 99.00 0.056287 5.63

 50.00 0.008261 0.83 99.50 0.067369 6.74

 60.00 0.010754 1.08 99.75 0.078791 7.88

 70.00 0.013670 1.37 99.90 0.085017 8.50

 80.00 0.017939 1.79
Page 41 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

Acute Reference Dose (aRfD) = 1.000000 mg/kg body-wt/day

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Adults 20-49 Daily Exposure Analysis 

------------ (mg/kg body-weight/day) 

 per Capita per User 

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

 Mean 0.015725 0.015729

 Standard Deviation 0.012900 0.012899

 Standard Error of mean 0.000113 0.000113

 Percent of aRfD 1.57 1.57

 Percent of Person-Days that are User-Days = 99.98%

 Estimated percentile of user-days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.002350 0.23 90.00 0.032053 3.21

 20.00 0.005266 0.53 95.00 0.040400 4.04

 30.00 0.007802 0.78 97.50 0.048828 4.88

 40.00 0.010277 1.03 99.00 0.059938 5.99

 50.00 0.012982 1.30 99.50 0.068782 6.88

 60.00 0.015963 1.60 99.75 0.076040 7.60

 70.00 0.019429 1.94 99.90 0.087506 8.75

 80.00 0.023968 2.40

 Estimated percentile of per-capita days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.002341 0.23 90.00 0.032051 3.21

 20.00 0.005261 0.53 95.00 0.040398 4.04

 30.00 0.007797 0.78 97.50 0.048825 4.88

 40.00 0.010274 1.03 99.00 0.059937 5.99

 50.00 0.012978 1.30 99.50 0.068777 6.88

 60.00 0.015961 1.60 99.75 0.076037 7.60

 70.00 0.019426 1.94 99.90 0.087504 8.75

 80.00 0.023965 2.40
Page 42 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

Acute Reference Dose (aRfD) = 1.000000 mg/kg body-wt/day

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Adults 50-99 Daily Exposure Analysis 

------------ (mg/kg body-weight/day) 

 per Capita per User 

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

 Mean 0.015540 0.015544

 Standard Deviation 0.011128 0.011127

 Standard Error of mean 0.000099 0.000099

 Percent of aRfD 1.55 1.55

 Percent of Person-Days that are User-Days = 99.97%

 Estimated percentile of user-days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.004160 0.42 90.00 0.028899 2.89

 20.00 0.006636 0.66 95.00 0.035998 3.60

 30.00 0.008841 0.88 97.50 0.043039 4.30

 40.00 0.010995 1.10 99.00 0.054354 5.44

 50.00 0.013358 1.34 99.50 0.062596 6.26

 60.00 0.015979 1.60 99.75 0.071509 7.15

 70.00 0.018836 1.88 99.90 0.085669 8.57

 80.00 0.022784 2.28

 Estimated percentile of per-capita days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.004153 0.42 90.00 0.028897 2.89

 20.00 0.006630 0.66 95.00 0.035994 3.60

 30.00 0.008838 0.88 97.50 0.043035 4.30

 40.00 0.010992 1.10 99.00 0.054352 5.44

 50.00 0.013354 1.34 99.50 0.062593 6.26

 60.00 0.015974 1.60 99.75 0.071504 7.15

 70.00 0.018833 1.88 99.90 0.085668 8.57

 80.00 0.022782 2.28
Page 43 of 46

US EPA Ver. 3.18, 03-08-d

DEEM-FCID ACUTE Analysis for CHLORIMURON NHANES 2003-2008 2-Day

Residue file: Chlorimuron.R08 Adjustment factor #2 NOT used.

Analysis Date: 04-08-2015/12:00:55 Residue file dated: 04-08-2015/11:58:43

Acute Reference Dose (aRfD) = 1.000000 mg/kg body-wt/day

RAC/FF intake summed over 24 hours

Run Comment: ""

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

Female 13-49 Daily Exposure Analysis 

------------ (mg/kg body-weight/day) 

 per Capita per User 

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

 Mean 0.015667 0.015667

 Standard Deviation 0.013165 0.013164

 Standard Error of mean 0.000123 0.000123

 Percent of aRfD 1.57 1.57

 Percent of Person-Days that are User-Days = 100.00%

 Estimated percentile of user-days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.001996 0.20 90.00 0.032752 3.28

 20.00 0.004917 0.49 95.00 0.040893 4.09

 30.00 0.007304 0.73 97.50 0.049529 4.95

 40.00 0.009968 1.00 99.00 0.060056 6.01

 50.00 0.012832 1.28 99.50 0.066956 6.70

 60.00 0.015862 1.59 99.75 0.072568 7.26

 70.00 0.019465 1.95 99.90 0.084457 8.45

 80.00 0.024234 2.42

 Estimated percentile of per-capita days falling below calculated exposure

 in mg/kg body-wt/day with Percent of aRfD

Percentile Exposure % aRfD Percentile Exposure % aRfD 

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

 10.00 0.001996 0.20 90.00 0.032752 3.28

 20.00 0.004917 0.49 95.00 0.040893 4.09

 30.00 0.007303 0.73 97.50 0.049529 4.95

 40.00 0.009968 1.00 99.00 0.060056 6.01

 50.00 0.012832 1.28 99.50 0.066956 6.70

 60.00 0.015862 1.59 99.75 0.072566 7.26

 70.00 0.019465 1.95 99.90 0.084457 8.45

 80.00 0.024234 2.42
Page 44 of 46

Appendix E. Nomenclature and Physical/Chemical Properties

TABLE E.1 Chlorimuron ethyl Nomenclature

Compound

Chlorimuron ethyl 

Common name Chlorimuron ethyl 

Company experimental name N/A

IUPAC name ethyl 2-(4-chloro-6-methoxypyrimidin-2-ylcarbamoylsulfamoyl)benzoate

CAS name ethyl 2-[[[[(4-chloro-6-methoxy-2-

pyrimidinyl)amino]carbonyl]amino]sulfonyl]benzoate

CAS # 90982-32-4

TABLE E.2 Physicochemical Properties of the Technical Grade Chlorimuron ethyl 

Parameter Value Reference

Melting point/range 181C PP#3G2959; 1/10/84; S. Creeger

pH 4.4 PP#3G2959; 1/10/84; S. Creeger

Density 1.51 g/cc PP#3G2959; 1/10/84; S. Creeger

Water solubility (mg/L) pH 1.3 = 1.5

pH 1.9 = 1.5

pH 2.5 = 1.5

pH 4.2 = 4.1

pH 5.0 = 9.0

pH 5.8 = 99

pH 6.5 = 450

pH 7.0 = 1200

PP#3G2959; 1/10/84; S. Creeger 

Solvent solubility 

(mg/100 mL at 25C)

Acetone = 7.05

Acetonitrile = 3.10

Benzene = 0.815

Ethyl Acetate = 2.36

Ethyl Alcohol = 0.392

n-Hexane = 0.006

Methyl Alcohol = 0.740

Methylene Chloride = 15.3

Xylene = 0.283

PP#3G2959; 1/10/84; S. Creeger

Vapor pressure at 25C 1.5 x 10-5 mm Hg PP#3G2959; 1/10/84; S. Creeger

Dissociation constant (pKa) at 25C 4.2 PP#3G2959; 1/10/84; S. Creeger

Octanol/water partition coefficient 

Log(KOW)

1.3 PP#3G2959; 1/10/84; S. Creeger
Page 45 of 46

Appendix F. Spray Drift Detailed Description

Off-target movement of pesticides can occur via many types of pathways and it is governed by a 

variety of factors. Sprays that are released and do not deposit in the application area end up offtarget and can lead to exposures to those the chemical may directly contact. Sprays can also 

deposit on surfaces where individuals come into contact with residues on these surfaces, leading

to indirect exposures (e.g., children playing on lawns where residues have deposited next to 

treated fields).

The approach to be used for quantitatively incorporating spray drift into risk assessment is based 

on a premise of compliant applications which, by definition, should not result in direct exposures 

to individuals because of existing label language and other regulatory requirements intended to 

prevent them12. [Direct exposures would include inhalation of the spray plume or being sprayed 

directly.] Rather, the exposures addressed here are thought to occur indirectly through contact 

with impacted areas, such as residential lawns, when compliant applications are conducted. 

Given this premise, exposures for children (1 to 2 years old) and adults who have contact with 

turf where residues are assumed to have deposited via spray drift thus resulting in an indirect 

exposure are the focus of this analysis analogous to how exposures to turf products are 

considered in risk assessment. 

In order to evaluate the drift potential and associated risks, an approach based on drift modeling 

coupled with techniques used to evaluate residential uses of pesticides was utilized. Essentially, a 

residential turf assessment based on exposure to deposited residues has been completed to 

address drift from the agricultural applications of chlorimuron ethyl. In the spray drift scenario, 

the deposited residue value was determined based on the amount of spray drift that may occur at 

varying distances from the edge of the treated field using the AgDrift (v2.1.1) model and the 

Residential Exposure Assessment Standard Operating Procedures Addenda 1: Consideration of 

Spray Drift Policy. Once the deposited residue values were determined, the remainder of the 

spray drift assessment was based on the algorithms and input values specified in the 2012 

Standard Operating Procedures for Residential Risk Assessment (SOPs). 

A screening approach was developed based on the use of the AgDrift model in situations where 

specific label guidance that defines application parameters is not available1314. AgDrift is 

appropriate for use only when applications are made by aircraft, airblast orchard sprayers, and

groundboom sprayers. When AgDrift was developed, a series of screening values (i.e., the Tier 1 

option) were incorporated into the model and represent each equipment type and use under 

varied conditions. The screening options specifically recommended in this methodology were 

selected because they are plausible and represent a reasonable upper bound level of drift for 

common application methods in agriculture. These screening options are consistent with how 

spray drift is considered in a number of ecological risk assessments and in the process used to 

develop drinking water concentrations used for risk assessment. In all cases, each scenario is to 

be evaluated unless it is not plausible based on the anticipated use pattern (e.g., herbicides are 

 

12 This approach is consistent with the requirements of the EPA’s Worker Protection Standard.

13 http://www.agdrift.com/

14 Note that for many cases the scenarios outlined in the screening approach represent actual use practice so risk 

assessors should be aware and characterize these appropriately.
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not typically applied to tree canopies) or specific label prohibitions (e.g., aerial applications are 

not allowed). Section 6.1.1 provides the screening level drift related risk estimates. 

In many cases, risks are of concern when the screening level estimates for spray drift are used as 

the basis for the analysis. In order to account for this issue and to provide additional risk 

management options additional spray drift deposition fractions were also considered. These drift 

estimates represent plausible options for pesticide labels.