UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

Date: September 10, 2015 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Triasulfuron. Draft Human Health Risk Assessment in Support of Registration 

Review. 

PC Code: 128969 DP Barcode: D425587 

Decision No.:499901 Registration No.: NA 

Petition No.: NA Regulatory Action: Registration Review 

Risk Assessment Type: Single Chemical Aggregate Case No.: 7221 

TXR No.: NA CAS No.: 82087-50-5 

MRID No.: NA 40 CFR: §180.459 

FROM: Monica Hawkins, Ph.D., M.P.H., Risk Assessor/Environmental Health Scientist~4 Yung Yang, Ph.D., Toxicologist &/-,_ 6-· 'L'-zr- . - , ! 

Julie 

Risk Assessment 

Van Alstine, 

Branch 

M.P.H., 

VI 

Envirorurllntal Healtn Scientist ~ V VVv ~ 

Health Effects Division (7509P) 

THROUGH: Donna S. Davis, Acting Branch Chief 

Risk Assessment Branch VI 

Health Effects Division (7509P) 

TO: Margaret Hathaway, Chemical Review Manager 

Cathryn Britton, Team Leader 

Kevin Costello, Branch Chief 

Risk Management and Implementation Branch 2 (RMIB 2) 

Pesticide Re-Evaluation Division (7508P) 

\ 

Since the last human health risk assessment and scoping document, the following updates have 

been incorporated for triasulfuron. 

1) The immunotoxicity and inhalation toxicity study requirements have been waived (TXR# 

0055323, TXR# 0056723, TXR# 0052986). 

2) Endpoints and points of departure have been selected for the incidental oral exposure 

scenario to assess spray drift exposure/risk estimates. 

3) The occupational risk assessment has been updated to incorporate new science policies. 

4) A refined-screening estimated drinking water concentration (EDWC) was used to assess 

triasulfuron dietary exposure and risk. 

Page 1 of29 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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Table of Contents 

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

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

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

3.0 Introduction .......................................................................................................................... 4

3.1 Chemical Identity and Physical/Chemical Characteristics ............................................... 4

3.2 Pesticide Use Pattern and Anticipated Exposure Pathways ............................................. 4

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

4.0 Hazard Identification/Toxicology ........................................................................................ 6

4.1 Summary of Toxicological Effects ....................................................................................... 6

4.2 Safety Factor for Infants and Children (FQPA Safety Factor) ............................................. 7

4.3 Toxicity Endpoint and Point of Departure Selections .......................................................... 7

4.4 Endocrine Disruptor Screening Program ......................................................................... 9

5.0 Dietary Exposure and Risk Assessment .............................................................................. 9

5.1 Food Residue Profile ........................................................................................................ 9

5.2 Water Residue Profile .................................................................................................... 10

5.3 Dietary Exposure and Risk Estimates ............................................................................ 10

6.0 Residential (Non-Occupational) Exposure/Risk Characterization .................................... 11

6.1 Spray Drift ...................................................................................................................... 11

6.1.1 Combined Risk Estimates from Lawn Deposition Adjacent to Applications .............. 11

6.2 Residential Bystander Post-Application Inhalation Exposure ....................................... 12

7.0 Aggregate Exposure/Risk Characterization ....................................................................... 13

8.0 Cumulative Exposure/Risk Characterization ..................................................................... 13

9.0 Occupational Exposure/Risk Characterization .................................................................. 13

9.1 Occupational Handler Exposure/Risk Estimates............................................................ 13

9.2 Occupational Post-application Exposure/Risk Estimates ................................................... 15

9.3 Occupational Post-application Inhalation Exposure/Risk Estimates .......................... 16

10.0 Public Health and Pesticide Epidemiology Data ............................................................... 17

11.0 Literature References ......................................................................................................... 17

12.0 References .......................................................................................................................... 18

Appendix A. Toxicology Data Requirements and Toxicology Profile ......................................... 19

Appendix B. Review of Human Research ................................................................................... 22

Appendix C. Occupational Non-cancer Algorithms .................................................................... 23

Appendix D. Dietary Exposure/Risk Modeling Input and Output ........................................... 25

Appendix E. Nomenclature and Physical/Chemical Properties .................................................... 27

Appendix F. Spray Drift Detailed Description ............................................................................. 28

Appendix G. Analytical Standards Summary .............................................................................. 29
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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1.0 Executive Summary 

Triasulfuron is a sulfonylurea herbicide that is currently registered for use in controlling 

broadleaf weeds on a variety of agricultural crops. It is currently registered for use on wheat, 

barley, pastures, and rangeland. This preliminary risk assessment (PRA) provides information 

to support the Registration Review of triasulfuron and addresses the exposures and risk estimates 

associated with all currently registered uses.

The toxicology database for triasulfuron is considered complete and adequate for risk 

assessment. The Hazard and Science Policy Council (HASPOC) has waived the subchronic 

inhalation, immunotoxicity, and neurotoxicity (acute and subchronic) studies for triasulfuron 

(TXR# 0055323, TXR# 0056723, TXR# 0052986). The last human health risk assessment for 

triasulfuron was completed in 2002 (D244111, D. Smegal). Since then, no new toxicity and/or 

metabolism data have been received. For this assessment, the toxicological endpoints and points 

of departure (PODs) have been updated to include a short-term oral endpoint in order to assess 

exposure from spray drift, and the short- and intermediated-term PODs were combined and 

updated for dermal and inhalation risk assessments. All other endpoints/PODs selected for risk 

assessment remain the same as in the previous assessments. 

The existing residue chemistry database for triasulfuron is complete and adequate for risk 

assessment purposes. No additional residue chemistry data are required at this time. 

For dietary exposure, HED has conducted a chronic dietary exposure and risk assessment for 

triasulfuron using tolerance-level residues in foods, 100% crop treated, and EDWCs provided by 

the Environmental Fate and Effects Division (EFED). Chronic dietary exposure and risk 

estimates (food and drinking water) are not of concern and are 6.8% of the chronic population 

adjusted dose (cPAD) for the general U.S. population and 17% of the cPAD for children 1-2 

years old, the most highly-exposed population subgroup. HED did not conduct an acute dietary 

exposure and risk assessment due to the lack of an appropriate endpoint for acute dietary 

assessment. Triasulfuron is classified as a Category E carcinogen with no evidence of 

carcinogenicity for humans; therefore, cancer risks are not of concern for triasulfuron. 

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

with triasulfuron. Therefore, residential handler and conventional residential post-application 

exposure assessments were not conducted to support Registration Review. A quantitative spray 

drift assessment was conducted. Risk estimates from groundboom and aerial applications are not 

of concern from the field edge for all scenarios considered. During Registration Review, the 

agency will utilize the Volatilization Screening Analysis to determine if data (i.e., flux studies, 

route-specific inhalation toxicological studies) or further analysis is required for triasulfuron. 

In the case of triasulfuron, aggregate exposure and risk estimates are equivalent to the dietary 

(food and water) exposure and risk estimates, and do not exceed HED’s level of concern (LOC).

The occupational handler exposure and risk estimates based on the highest application rate and 

amount handled scenario indicate that the short- and intermediate-term dermal and inhalation 

margins of exposure (MOEs) are not of concern to HED (i.e., MOEs ≥ the level of concern 

(LOC) of 100). The dermal and inhalation MOEs ranged from 1,900 to 15,000. Occupational 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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post-application exposure and risk estimates indicate that the short- and intermediate-term MOEs 

are not of concern to HED on the day of application (i.e., MOE ൒ the LOC of 100). The MOEs 

ranged from 1,200 to 19,000. Based on the Agency's current practices, a quantitative non-cancer 

occupational post-application inhalation exposure assessment was not performed for triasulfuron. 

If new policies or procedures are put into place, the Agency may revisit the need for such an 

assessment for triasulfuron. 

The restricted entry interval (REI) of 4 hours specified on the registered labels is based on the 

acute toxicity of triasulfuron. Upon review of the criteria for the active ingredient only, it 

appears that triasulfuron is consistent with the criteria in PRN 95-3 that allow for a 4-hour REI. 

Note: The PR Notice also includes similar criteria for the end-use product. These criteria have 

not been evaluated by HED. Based solely on the active ingredient criteria, HED would 

recommend for reduction of the REI for triasulfuron.

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

intentionally exposed to a pesticide or other chemical. For a list of data sources see appendix B. 

2.0 HED Recommendations 

2.1 Tolerance Considerations 

The existing tolerances for residues of triasulfuron (40 CFR §180.459) are supported by the 

available residue chemistry data. Codex has not established maximum residue limits (MRLs) for 

residues of triasulfuron. Canada has established MRLs for triasulfuron which are harmonized 

with U.S. tolerances. 

HED notes that the tolerance expression for triasulfuron in 40 CFR §180.459 requires revision to 

state the following: 

(a) General. Tolerances are established for residues of triasulfuron, including its 

metabolites and degradates, in or on the commodities in the table below. Compliance 

with the tolerance levels specified below is to be determined by measuring only 

triasulfuron (2-(2-chloroethoxy)-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-

yl)amino]carbonyl]benzenesulfonamide) in or on the commodity. 

3.0 Introduction 

3.1 Chemical Identity and Physical/Chemical Characteristics 

Triasulfuron (2-(2-chloroethoxy)-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-

yl)amino]carbonyl]benzenesulfonamide) is a selective herbicide used for pre-emergence control 

of broadleaf and grassy weeds. The nomenclature and physical/chemical properties of 

triasulfuron are provided in Appendix E. 

3.2 Pesticide Use Pattern and Anticipated Exposure Pathways
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Triasulfuron is currently registered for use on wheat, barley, pastures, and rangeland. There are 

several end-use product labels registered with triasulfuron as the active ingredient. These 

include water-dispersible granules in water-soluble packet (WSP) formulations. The registered 

products are applied either with aerial or groundboom equipment. The single application rate of 

the registered uses for triasulfuron ranges from 0.026 to 0.027 lb ai/A. 

Exposure Pathways 

Individuals may be exposed to triasulfuron via their diet (food and drinking water). There are no 

registered uses for triasulfuron that will result in direct non-dietary (i.e., residential and 

occupational) exposures. However, there is the potential for indirect exposure (incidental oral 

and dermal) to triasulfuron related to spray drift. Both handler and post-application occupational 

exposure is also possible for triasulfuron. Agricultural workers may be exposed (dermal and 

inhalation) to triasulfuron during mixing, loading, and/or applying the herbicide as well as during 

post-application activities. 

Based on the use pattern for triasulfuron, short- and intermediate-term dermal and inhalation 

exposures for occupational handlers and occupational post-application workers are expected; 

long-term exposures (greater than 6 months) are not anticipated. The triasulfuron labels require 

handlers to wear baseline attire (i.e., a long sleeved shirt, long pants, shoes plus socks) and 

chemical-resistant gloves. 

Table 3.2 provides a summary of the highest application rate of the registered uses for 

triasulfuron. 

Table 3.2. Summary of Registered Uses of Triasulfuron. 

Application 

Equipment 

Formulation 

Maximum 

Application 

Rate 

REI Use Directions and 

Limitations 

Wheat 

Groundboom, 

Aerial 

Waterdispersible 

granule in 

WaterSoluble 

Packets

0.027 lb ai/A 4 hours 

Do not apply this product 

through any type of 

irrigation system.

Barley

Groundboom, 

Aerial 

Waterdispersible 

granule in 

WaterSoluble 

Packets 

0.026 lb ai/A 4 hours

Do not apply this product 

through any type of 

irrigation system.

Pastures, Rangeland

Groundboom, 

Aerial 

Waterdispersible 

granule in 

0.027 lb ai/A 4 hours

Do not apply this product 

through any type of 

irrigation system.
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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Table 3.2. Summary of Registered Uses of Triasulfuron. 

Application 

Equipment 

Formulation 

Maximum 

Application 

Rate 

REI Use Directions and 

Limitations 

WaterSoluble 

Packets 

3.3 Consideration of Environmental Justice 

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

human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions 

to Address Environmental Justice in Minority Populations and Low-Income Populations," 

(http://epa.gov/compliance/ej/resources/policy/exec_order_12898.pdf). 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 U.S. Department of 

Agriculture (USDA) under the National Health and Nutrition Examination Survey, What We Eat 

in America, (NHANES/WWEIA; 2003-2008) 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 triasulfuron is complete and adequate for risk assessment. The 

Hazard and Science Policy Council (HASPOC) has determined that subchronic inhalation, 

immunotoxicity, and neurotoxicity (acute and subchronic) studies are not required at this time for 

triasulfuron (TXR# 0055323, TXR# 0056723, TXR# 0052986). No new toxicity and/or 

metabolism data have been received since the last risk assessment (D244111, D. Smegal). The 

toxicological endpoints and PODs have been updated to include a short-term oral endpoint for 

the purpose of assessing exposure from spray drift, and the short and intermediate-term PODs 

were combined for dermal and inhalation risk assessments. All other endpoints/PODs selected 

for risk assessment remain the same as those used in the previous assessment. See Appendix A.2 

for the triasulfuron toxicological profile. 

4.1 Summary of Toxicological Effects 
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The most prevalent effect observed was decreased body weight in rats and dogs. The major 

target organ in mice is the liver (centrilobular hepatocytomegaly); while the most sensitive 

toxicological finding is decreased body weights in rats. In dogs, prostate cystic hyperplasia was 

observed following chronic exposure. In rodents, triasulfuron caused developmental effects 

(delayed skeletal maturation) and reproductive effects only at high doses that also induced 

maternal and/or parental toxicity. The HED RfD/Peer Review Committee classified triasulfuron 

as a Category E carcinogen, no evidence of carcinogenicity for humans (TXR 0012651). There is 

no mutagenicity concern for triasulfuron. 

There is no concern for increased quantitative or qualitative susceptibility of the young following 

in utero and pre- and post-natal exposure to triasulfuron based on the results from developmental 

studies conducted with rats and rabbits, as well as a two-generation reproduction study 

conducted with rats.. 

In acute lethality studies, triasulfuron has low toxicity via the oral, dermal, and inhalation routes 

of exposure (Category III and IV). It is non-irritating to the skin (Category IV), and it is not a 

skin sensitizer. It is slightly irritating to the eye (Category III). The acute toxicity of triasulfuron 

is presented in Appendix A.2. 

Triasulfuron is rapidly absorbed and excreted within 96 hours of dosing: 74-99% in urine and 2-

14% in feces. Elimination rates after repeated oral dosing were faster than after single dosing. 

Residue levels in tissue were < 0.1% of the administered dose. Metabolite patterns in urine, 

fecal and liver extracts show mainly the parent compound. The variety of minor metabolites 

include 12 urinary (6.6-8.1%) and 10 fecal (1.2-2.9%) of the administered radioactivity, 

respectively. No significant differences in metabolite patterns between sexes. 

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

HED has recommended that the 10x Food Quality Protection Act (FQPA) Safety Factor (SF) be 

reduced to 1X for triasulfuron. The toxicology database is complete, there is no evidence of 

increased susceptibility, no concerns/residual uncertainties with regard to pre- and/or postnatal 

toxicity, and no concern for neurotoxicity. In addition, HED is confident that the dietary (food 

and drinking water) assessment does not underestimate risk to the general U.S. population or any 

population subgroup. 

4.3 Toxicity Endpoint and Point of Departure Selections 

The toxicological endpoints/PODs have been updated to include a short-term oral endpoint, and 

the short and intermediated-term PODs were combined for dermal and inhalation risk 

assessments. Otherwise, the No Observed Adverse Effect Levels (NOAELs) and Lowest 

Observed Adverse Effect Levels (LOAELs) have not been revised from the previous risk 

assessment. The PODs selected for risk assessment are protective of the effects observed in the 

triasulfuron database. A summary of toxicological doses and endpoints used in the triasulfuron 

human health risk assessments is presented below. 
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Table 4.3.1. Toxicological Doses and Endpoint for Triasulfuron for Use in Dietary and Non-Occupational 

Human Health Risk Assessment

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) 

N/A N/A N/A An appropriate endpoint 

attributable to a single 

exposure (dose) was not 

identified from oral toxicity 

studies including the 

developmental toxicity studies 

in rats and rabbits.

Chronic Dietary (all 

populations) 

NOAEL = 1.2 

mg/kg/day 

UFA = 10X 

UFH = 10X 

FQPA SF = 1X 

Chronic RfD 

= 0.01 mg/kg/day 

cPAD = 0.01 mg/kg/day 

Chronic /CarcinogenicityMice (MRID 40728316)

LOAEL = 129 mg/kg/day 

based on centrilobular 

hepatomegaly in male mice

Incidental Oral 

(Short- Term) 

NOAEL=10 

mg/kg/day 

UFA = 10X 

UFH = 10X 

FQPA SF = 1X 

Residential LOC for 

MOE= 100 

Subchronic Toxicity-Rat 

(MRID 40271947) 

LOAEL=500 mg/kg/day 

based on decreased body 

weight and food intake in both 

sexes of rats.

Cancer (oral, dermal, 

inhalation) 

Classification: Category E carcinogen, no evidence of carcinogenicity for humans. 

A carcinogenic risk assessment for triasulfuron is not required. 

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

mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL 

= no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA = 

extrapolation from animal to human (interspecies). UFH = potential variation in sensitivity among members of the human 

population (intraspecies). FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). 

Table 4.3.2. Summary of Toxicological Doses and Endpoints for Triasulfuron 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 

Dermal exposure 

(short- and 

intermediated-term) 

Oral 

NOAEL = 10 

mg/kg/day 

UFA = 10x 

UFH =10x 

Dermal 

Absorption 

 = 100% 

Occupational LOC for 

MOE = 100 

Subchronic Toxicity-Rat 

(MRID 40271947) 

LOAEL=500 mg/kg/day based 

on decreased body weight and 

food intake in both sexes of 

rats.

Inhalation exposure 

(Short- & intermediate 

term) 

Oral 

NOAEL = 10 

mg/kg/day 

UFA = 10x 

UFH =10x 

Inhalation 

Absorption 

 = 100% 

Occupational LOC for 

MOE = 100 

Subchronic Toxicity-Rat 

(MRID 40271947) 

LOAEL=500 mg/kg/day based 

on decreased body weight and 

food intake in both sexes of 

rats. 

Cancer (oral, dermal, 

inhalation) 

Classification: Category E carcinogen, no evidence of carcinogenicity for humans. 

A carcinogenic risk assessment for triasulfuron is not required. 

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). MOE = margin of exposure. LOC = level of concern. 
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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 re-registration decision for triasulfuron, 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), 

triasulfuron 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 

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, 20131

 and includes some 

pesticides scheduled for registration review and chemicals found in water. Neither of these lists 

should be construed as a list of known or likely endocrine disruptors. 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. 2 

5.0 Dietary Exposure and Risk Assessment 

5.1 Food Residue Profile 

 

1

 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of chemicals. 2 http://www.epa.gov/endo/
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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The existing residue chemistry database for triasulfuron is complete and adequate for risk 

assessment purposes. No additional residue chemistry data are required at this time. The nature 

of the residue in plants and animals is adequately understood. The residue of concern for risk 

assessment and tolerance enforcement is the parent compound only (Memo, R. Schmitt, 

06/22/1989, PP#8F3658). HED has previously concluded that Method AG-500B is acceptable to 

enforce tolerances (Memo, G. Kramer, 02/16/1994, D193754). 

5.2 Water Residue Profile 

Screening ground water-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. EFED initially provided coarse-screen estimates that should 

exceed the upper-bound chemical-specific EDWCs for any SU; however, for several of the SUs, 

the coarse-screen EDWCs resulted in dietary risks of concern and EFED subsequently generated 

refined-screen EDWCs for these SUs. The application inputs for the refined-screen EDWCs 

represent the maximum application rate pattern for the chemical, considering the maximum 

single application rate first, then the maximum seasonal application rate, using usage data 

provided by BEAD if the labels do not provide a maximum seasonal rate. The modeled sorption 

coefficient is also chemical-specific. All other inputs, including the screening assumptions of 

stability to degradation and application every year, remained the same as for the coarse screen. 

The resulting refined-screen EDWCs from PRZM-GW can be used as a conservative estimate of 

exposure and are summarized in Table 5.1 (G. Orrick, D427429, 8/12/15). 

The chronic dietary assessment for triasulfuron used the refined-screen post-breakthrough mean 

value of 19 μg/L (0.019 ppm). 

Table 5.1. PRZM-GW Refined-Screen EDWCs for Sulfonylureas.1

Sulfonylurea (Use)

PRZM-GW 

Scenario Max. Daily Conc. 

(μg/L)

Post-breakthrough 

Mean (μg/L)

Mean 

Breakthrough 

Time (years)

Chlorsulfuron (non-ag areas) NC cotton 78 52 5.9 

Halosulfuron-methyl (fallow) NC cotton 74 53 8.1 

Nicosulfuron (rights-of-way) NC cotton 39 26 6.2 

Prosulfuron (corn) NC cotton 15 13 12 

Rimsulfuron (commercial areas) NC cotton 105 71 6.5 

Triasulfuron (rangeland) NC cotton 21 19 16 

Tribenuron-methyl (corn) NC cotton 35 23 6.1 

Triflusulfuron-methyl 

(sugarbeet) 

FL citrus 23 20 9.5 

1

 The triasulfuron drinking water estimates are in bold. 

5.3 Dietary Exposure and Risk Estimates 

HED has conducted a chronic dietary exposure and risk assessment for triasulfuron using 

tolerance-level residues in foods, 100% crop treated, and EDWCs provided by EFED. 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 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

Page 11 of 29

data from the 2003-2008 National Health and Nutrition Examination Survey/What We Eat in 

America (NHANES/WWEIA) database, coupled with recipe files and residues in foods, to 

derive estimates of dietary exposure and risk. 

Generally, HED is concerned when chronic dietary exposure estimates exceed 100% of the 

chronic population adjusted dose (cPAD). Chronic dietary risk estimates (food and drinking 

water) are not of concern for the general U.S. population or any other population subgroup 

(Table 5.3). The chronic exposure estimate is 6.8% of the cPAD for the general U.S. population 

and 17% of the cPAD for children 1-2 years old, the most highly-exposed population subgroup. 

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. HED did not conduct an acute dietary exposure and 

risk assessment due to the lack of an appropriate endpoint for acute dietary assessment. 

Triasulfuron is classified as a Category E carcinogen with no evidence of carcinogenicity for 

humans; therefore, cancer risks are not of concern for triasulfuron. 

Table 5.3. Summary of Chronic Dietary Exposure (Food and Drinking Water) and Risk for Triasulfuron1.

Population Subgroup 

Chronic Dietary 

Dietary Exposure (mg/kg/day) % cPAD 

General U.S. Population 0.000677 6.8 

All Infants (<1 year old) 0.001330 13 

Children 1-2 years old 0.001716 17 

Children 3-5 years old 0.001250 13 

Children 6-12 years old 0.000824 8.2 

Youth 13-19 years old 0.000547 5.5 

Adults 20-49 years old 0.000604 6.0 

Adults 50-99 years old 0.000570 5.7 

Females 13-49 years old 0.000581 5.8 

1

 Population with the greatest exposure is in bold. Exposure and risk estimates calculated using DEEM version 3.18.

6.0 Residential (Non-Occupational) Exposure/Risk Characterization 

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

associated with triasulfuron. Therefore, a quantitative residential exposure assessment for direct 

residential uses 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. Triasulfuron is used on wheat, 

barley, pastures, and rangeland and can be applied via groundboom and aerial equipment. The 

spray drift assessment was conducted using the highest registered application rate of 0.027 lb 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

Page 12 of 29

ai/acre for use on wheat. 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-tomedium 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).3

Dermal risk estimates have been evaluated for adults. Dermal and incidental oral risk estimates 

were evaluated for children (1 to < 2 years old). The total applicable LOC is 100 so MOEs < 

100 would be of concern. Children’s (1 < 2 years old) dermal and incidental oral risk estimates 

and adult dermal risk estimates from exposure to triasulfuron related to spray drift result in no 

risks of concern at the field edge for either groundboom or for aerial applications. Results are 

presented in Tables 6.1.1 and 6.1.2 below. 

Table 6.1.1. Adult Risk Estimates (MOEs) Related to Indirect Exposure to Spray Drift for Triasulfuron 

for the Dermal Route of Exposure

Crop/Rate 

Group 

Spray Type/ 

Nozzle 

Configuration 

Application 

Rate (lb ai/A) 

Estimated or Adjusted 

TTR (ug/cm2) 

Edge-of-Field 

Dermal MOE 

Wheat

Aerial Fine to Medium 

0.027 0.00300105

3,800 

Groundboom High Boom Very 

fine to Fine 5,300 

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

Drift for Triasulfuron for Combined Route of Exposure

Crop/Rate 

Group 

Spray Type/ 

Nozzle 

Configuration 

Application 

Rate (lb ai/A) 

Estimated or Adjusted 

TTRt (ug/cm2) 

 Edge-of-Field 

 Combined MOE1 

Wheat

Aerial Fine to Medium 

0.027 0.00300105

 1,900 

Groundboom High Boom Very 

fine to Fine 2,600 

1. Dermal and incidental oral risks were combined for children 1 to < 2 years old. 

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 

 

3

 AgDrift® allows for consideration of even finer spray patterns characterized as very fine to fine. However, this 

spray pattern was not selected as the common screening basis since it is used less commonly for most agriculture. If 

assessors identify this use pattern, then it should be used as the screening criteria and deposition values associated 

with it ae provided in Table 1 below. Justification for including this spray quality should be included in any 

assessment based on specific label directions for its use. 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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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 

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

studies) or further analysis is required for triasulfuron. 

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 triasulfuron, aggregate exposure and risk estimates 

are equivalent to the dietary (food and water) exposure and risk estimates in Section 5, above, 

and are below HED’s LOC.

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)5

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

this framework to evaluate the SUs of which [chemical name] 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 exposure associated with handler activities (i.e., mixing, loading, and applying) is 

expected from the registered use on wheat, barley, pastures, and rangeland. The quantitative 

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

Table 9.1.1. Based on the use patterns (i.e., 1 application per season) and resistance 

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

short-term (1-30 days) and intermediate-term (1-6 months) and in duration. Long-term 

 

4

 Available at: http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219. 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) 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

Page 14 of 29

exposures (greater than 6 months) are not anticipated. The registered labels require handlers to 

wear baseline attire and chemical resistant gloves. 

Occupational Handler Exposure Data and Assumptions 

Application Rate: The highest application rate of the registered uses is listed in Table 3.2. 

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, the AHETF database, the Outdoor Residential Exposure Task Force 

(ORETF) database, or other registrant-submitted occupational exposure studies. 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” which, along with additional information on 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 area treated or amount handled is based on HED 

ExpoSAC Policy No. 9.1. Refer to Table 9.1.1. for these assumptions for each scenario. 

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 Estimates 

The short- and intermediate-term dermal and inhalation risk estimates for the occupational 

handlers are greater than HED’s LOC (i.e., MOEs ≥ 100) at baseline for all scenarios, with 

MOEs ranging from 2,400 to 15,000. Table 9.1.1. provides the worst-case scenarios for the 

registered uses for triasulfuron. 

 

7

 Available: http://www.epa.gov/opp00001/science/handler-exposure-table.pdf 8

 Available: http://www.epa.gov/pesticides/science/handler-exposure-data.html
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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Table 9.1.1. Occupational Short-term/Intermediate-term Handler Exposure and Risk Estimates for 

Triasulfuron. 

Exposure 

Scenario 

Crop or 

Target1 

Baseline 

Dermal 

Unit 

Exposure2 

Baseline 

Inhalation 

Unit 

Exposure2 

Maximum

Application 

Rate3

Area 

Treated 

or 

Amount 

Handled 

Daily4

Baseline Dermal Baseline Inhalation Total 

Dose5 MOE6 Dose5 MOE6

MOE7

μg/lb ai μg/lb ai lb ai/A Acres mg/kg/day LOC = 

100 mg/kg/day LOC = 100 

LOC = 

100

Mixer/Loader 

Water 

dispersible 

granule in 

watersoluble 

packet for 

aerial 

application 

Wheat 9.8 

(EC) 0.24 0.027 1,200 0.00398 2,500 0.0000973 100,000 2,400 

Waterdispersible 

granule in 

watersoluble 

packet for 

groundboom 

application 

Wheat 9.8 

(EC) 0.24 0.027 200 0.000661 15,000 0.0000163 610,000 

15,000 

Applicator 

Aerial 

Application Wheat 2.08 

(EC) 0.0049 0.027 1,200 0.000843 12,000 0.00000199 5,000,000 12,000 

Groundboom 

Application Wheat 78.6 0.34 0.027 200 0.0053 1,900 0.000023 430,000 1,900 

Flagger

Flagger Wheat 11 0.35 0.027 350 0.0013 7,700 0.0000414 240,000 7,500 

1 The worst-case scenarios for the registered uses for triasulfuron are listed in this table. 

2 “Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table”; Level of mitigation = Baseline except for aerial 

applicator which includes engineering controls. 

3 Based on the currently registered labels (See Table 3.2). 

4 Exposure Science Advisory Council Policy #9.1. 

5 Dermal Dose = Dermal Unit Exposure (μg/lb ai) ) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre) × Area Treated or 

Amount Handled Daily (A or gal/day) x DAF (%) ÷ BW (80 kg). Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor 

(0.001 mg/μg) × Application Rate (lb ai/acre) × Area Treated or Amount Handled Daily (A or gal/day) ÷ BW (80 kg). 

6 Dermal MOE = Dermal NOAEL (10 mg/kg/day) ÷ Dermal Dose (mg/kg/day). Inhalation MOE = Inhalation NOAEL (10 mg/kg/day) ÷ 

Inhalation Dose (mg/kg/day). 

7 Total MOE = NOAEL (10 mg/kg/day) ÷ Dermal Dose + Inhalation Dose. 

9.2 Occupational Post-Application Dermal Exposure/Risk Estimates 

Occupational post-application exposure is expected based on the registered agricultural products 

for triasulfuron. In accordance with 40 CFR Part 158, dislodgeable foliar residue (DFR) data are 

required for all occupational (e.g., crop, nursery, greenhouse use sites) or residential (e.g., 

ornamental and vegetable gardens, pick your own farms, retail tree farms) uses that could result 

in post-application exposure to foliage. HED developed a waiver policy for DFR studies. The 

MOEs from the assessment, using default values are evaluated. If those are 2 times higher than 

the LOC the DFR studies can be waived. 

Since the highest estimated occupational post-application exposure using default DFR values for 

triasulfuron is minimal in comparison to the LOC (i.e., the calculated MOE is greater than 2 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

Page 16 of 29

times higher than the LOC, MOE = 1,200 compared to the LOC of 100); EPA is waiving the 40 

CFR Part 158 DFR data. In this instance, it is unlikely that chemical-specific DFR data would 

be needed to further refine exposure assessments or would add appreciably to our overall 

understanding of the availability of dislodgeable foliar pesticide residues for triasulfuron. 

Table 9.2.1 provides a summary of the anticipated post-application activities and associated 

transfer coefficients for the worst-case scenarios for the registered uses for triasulfuron. 

Table 9.2.1. Anticipated Post-Application Activities and Dermal Transfer Coefficients. 

Proposed Crops Policy Crop 

Group Category 

Crop 

Height 

Foliage 

Density 

Transfer Coefficients 

(cm2/hr) Activities 

Wheat Cereal Grain Low Min/Full 70 Hand Weeding 

Wheat Cereal Grain Low Min/Full 1,100 Scouting 

Occupational Post-Application Non-Cancer Dermal Risk Estimates 

The short- and intermediate-term post-application exposure scenarios associated with the highest 

uses for triasulfuron are summarized in Table 9.2.2. All scenarios resulted in MOEs greater than 

the LOC of 100 (ranging from 1,200 to 19,000) on day 0 (12 hours after application); and, 

therefore, are not of concern to HED. The restricted entry interval (REI) specified on the 

registered labels is 4 hours. Table 9.2.2 provides MOEs reflecting the worst-case scenarios for 

the registered uses for triasulfuron.

Table 9.2.2. Occupational Post-Application Non-Cancer Exposure and Risk Estimates for Triasulfuron.

Crop/Site Activities 

Transfer 

Coefficient 

(cm2/hr) 

Application Rate 

(lb ai/A) DFR1 Dermal Dose 

(mg/kg/day)2 MOE3

Short- and Intermediate-term 

Wheat Hand Weeding 70 0.027 0.08 0.001 19,000 

Wheat Scouting 1,100 0.027 0.08 0.008 1,200 

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 (100 %)]  BW (80 kg).

3 MOE = POD (mg/kg/day) / Daily Dermal Dose. Daily Dermal Dose = [DFR (μg/cm2

) × TC × 0.001 mg/μg × 8 hrs/day × dermal 

absorption factor (100 %)]  BW (80 kg). 

9.3 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 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

Page 17 of 29

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 triasulfuron. 

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/commercial 

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. 

Restricted Entry Interval 

Triasulfuron is classified as Toxicity Category III or IV based upon data for acute dermal 

toxicity, acute inhalation toxicity, primary skin irritation, and primary eye irritation. Upon 

review of the criteria for the active ingredient only, it appears that triasulfuron is consistent with 

the criteria in PRN 95-3 that allow for a 4-hour REI. Note: The PR Notice also includes similar 

criteria for the end-use product. These criteria have not been evaluated by HED. Based solely 

on the active ingredient criteria, HED would recommend for reduction of the REI for 

triasulfuron. 

10.0 Public Health and Pesticide Epidemiology Data 

The OPP Incident Data System (IDS), the Centers for Disease Control and Prevention/National 

Institute for Occupational Safety and Health (CDC/NIOSH) Sentinel Event Notification System 

for Occupational Risk-Pesticides (SENSOR) databases were consulted for pesticide incident data 

on the active ingredient triasulfuron (S. Recore, 12/08/2011, D396006). In Aggregate IDS and 

Main IDS, from January 1, 2006 to June 6, 2011 there was 1 incident involving triasulfuron. 

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.” An IDS analysis was conducted from June 2011 to February 25, 2015; no 

incidents (Aggregate or Main IDS) were reported for triasulfuron. Triasulfuron is not included 

in the Agricultural Health Study (AHS), and therefore this study does not provide information 

for this report. The Agency will continue to monitor the incident information and if a concern is 

triggered, additional analysis will be included in the risk assessment.

11.0 Literature References 

A literature search was performed for triasulfuron. The search did not reveal information that 

would impact the current risk assessment. 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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12.0 References 

Author Barcode Date Title 

P. Yvonne 

Barnes, 

M. Hawkins, 

Y. Yang

D394284 2/28/2012 Triasulfuron: Human Health Assessment Scoping Document in 

Support of Registration Review 

S. Recore D396006 12/13/2011 Triasulfuron: Review of Human Incidents

D. Smegal, 

P. Hurley, 

M. Nelson, 

M. Collantes

D244111 7/10/1998 Triasulfuron: Human Health Risk Assessment for Use on Grasses. 

P. Barnes et 

al. D394284 02/28/2012 Triasulfuron: Registration Review Scoping Document for Human 

Health Assessments.

R. Schmitt -- 06/22/1989 New Chemical Review of Triasulfuron

G. Kramer D193754 02/16/1994

PP#3F04225. Triasulfuron in or on grass forage, fodder, and hay 

group. Evaluation of residue data and analytical methods. 

MRID#s 427716-01, 428519-01 and -02. Barcodes D193754 & 

D193756. CBTS#s 12818 & 12319.

G. Orrick D427429 8/12/15 Drinking Water Exposure Assessment for the Registration Review 

of 22 Sulfonylurea Herbicides

 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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Appendix A. Toxicology Data Requirements and Toxicology Profile 

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

Table A.1. Toxicology Data Requirements for Triasulfuron 

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 90-Day Inhalation .......................................................... 

yes 

yes 

yes 

no 

CR 

yes 

yes 

yes

- 

waived1 

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 

no 

yes 

yes 

yes 

yes 

- 

yes 

yes 

yes 

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

870.5xxx Mutagenicity—Structural Chromosomal Aberrations ... 

870.5xxx Mutagenicity—Other Genotoxic Effects ....................... 

yes 

yes 

yes 

yes 

yes 

yes 

870.6100a Acute Delayed Neurotox. (hen) ..................................... 

870.6100b 90-Day Neurotoxicity (hen) .......................................... 

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

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

870.6300 Develop. Neuro ............................................................. 

no 

no 

yes 

yes 

no 

- 

- 

waived1 

waived1 

- 

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

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

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

yes 

no 

yes 

yes 

- 

Waived1 

1

HASPOC recommends that the 21-day dermal, subchronic inhalation toxicity, immunotoxicity, and neurotoxicity battery studies are not required 

at this time (TXR# 0055323, TXR# 0056723, TXR# 0052986). 

 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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A.2. Toxicity Profiles 

Table A.2.1. Acute Toxicity Profile for Triasulfuron 

OPPTS 

Guideline Study Type 

MRID 

Number 

Results Toxicity 

Category 

870.1100 Acute oral toxicity 

in Rats 

40271931 

40271930 LD50 >5000 mg/kg IV 

870.1200 Acute dermal toxicity 

in Rats 

40271932 LD50 >2000 mg/kg III 

870.1300 Acute inhalation toxicity 

in Rats 40271933 LC50 >5.185 mg/L/4 hrs IV 

870.2400 Acute eye irritation 

in Rabbits 

40271937 Mild conjunctival irritation, 

subsided by day 7 III 

870.2500 

Acute dermal irritation 

In Rats 

40271935 Very slight erythema and 

edema. IV 

870.2600 

Skin sensitization 

In Guinea Pigs 40271938 Negative NA 

NA = Not applicable because a Toxicity Category is not assigned for this particular type of acute study. 

Table A.2.2. Subchronic, Chronic and Other Toxicity Study for Triasulfuron 

Guideline No./ Study Type MRID No. (year) 

Doses / Classification 

Results 

870.3100 

90-Day oral toxicity 

rats 

40271947 (1985) 

Acceptable/guideline 

NOAEL: 10 mg/kg/day 

LOAEL: 500 mg/kg/day based on decreased weight gain 

and food intake in both sexes. 

870.3200 

21-Day dermal toxicity 

rabbits 

 41585801 (1986) 

Acceptable/guideline 

NOAEL for irritation: 1,000 mg/kg/day 

NOAEL for systemic effects: not identified 

LOAEL for systemic effects: 10 mg/kg/day based on

dyspnea, and ruffled fur that were not considered 

appropriate endpoints for human risk assessment. 

870.3700a 

Prenatal developmental 

rats 

40271948 (1986) 

Acceptable /guideline 

Maternal NOAEL: 100 mg/kg/day 

Maternal LOAEL: 300 mg/kg/day based on decreased 

body weight and decreased body weight gain during 

gestation. 

Developmental NOAEL: 300 mg/kg/day 

Developmental LOAEL: 900 mg/kg/day (HDT) based on 

reduced ossification of vertebrae, metatarsals and 

phalanges. 

870.3700b 

Prenatal developmental 

rabbits 

40271949 (1986) 

Acceptable/guideline 

Maternal NOAEL: 120 mg/kg/day 

Maternal LOAEL: 240 mg/kg/day based on reduced 

maternal weight gain during gestation. 

Developmental NOAEL: >240 mg/kg/day (HDT) 

870.3800 

Reproduction and fertility 

effects 

rats 

40728317 (1987) 

Acceptable/guideline 

Parental NOAEL: 50 mg/kg/day 

Parental LOAEL: 250 mg/kg/day based on significant 

decreases in premating and total body weight gain for F0 

and F1 parental animals. 

Reproductive NAOEL: 50 mg/kg/day 

Reproductive LOAEL: 250 mg/kg/day (HDT) based on 

reduced F1a pup weights at birth and during lactation. 

870.4100b 40271965 and 

40542401(1986) 

NOAEL: 2.5 mg/kg/day 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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Table A.2.2. Subchronic, Chronic and Other Toxicity Study for Triasulfuron 

Guideline No./ Study Type MRID No. (year) 

Doses / Classification 

Results 

Chronic toxicity dogs Acceptable/guideline LOAEL: 25 mg/kg/day based on increased prostate cystic 

hyperplasia. 

870.4300 

Combined Chronic / 

Carcinogenicity 

rats 

40728318 and 41585802 

(1987) 

Acceptable/guideline 

NOAEL: 32.1 mg/kg/day 

LOAEL: 220.8 mg/kg/day based on decreased mean 

body weight and decreased body weight gain. Negative 

for carcinogenicity. 

870.4300 

Carcinogenicity mice 

40728316 (1988) 

Acceptable/guideline 

NOAEL = 1.2 mg/kg/day 

LOAEL: 129 mg/kg/day based on centrilobular 

hepatocytomegaly in males. There was no evidence of 

oncogenicity. 

Reverse gene mutation - 

Salmonella typhimurium 

870.5100 

40271951 (1983) 

Acceptable/guideline 

Strains TA 98, 100, 1535, 1537, 1538 tested at 0, 4, 16, 

64, 256 μg/0.1 ml in absence and presence of metabolic 

activation. Negative up to cytotoxic concentrations, 64 

and 256 μg/0.1 ml. 

Reverse gene mutation, 

recombination and gene 

conversion in Saccharomyces 

cerevisiae 

870.5300 

40271952 (1984) 

Provisionally Acceptable 

Strain D7 exposed to test article at 0, 46.9, 187.5,750, 

3000 μg/ml in absence and presence of metabolic 

activation. Negative up to 3000 μg/ml. Deficiency: not 

tested up to limit concentration for negative study: 5000 

μg/ml. Provisionally acceptable pending toxicity test 

and new study at 5000 μg/ml. 

Forward gene mutation in 

mammalian cells: L5178Y/TK 

870.5375 

40271953 (1986) 

 Acceptable 

Cells tested with and without metabolic activation at 0, 

260, 520, 1040, 1560, 2080, 2340, 2600 μg/ml and 0, 

300, 600, 1200, 1800, 2400, 2700, 3000 μg/ml, 

respectively. Negative up to levels of moderate 

cytotoxicity. 

In vivo cytogenicity study 

(micronucleus/Chinese 

hamsters) 

40271954 (1984) 

Acceptable 

Administered orally to Chinese hamsters at 0, 625, 1250, 

2500 mg/kg/day on each of 2 consecutive days. Negative 

for induction of micronuclei and/or other nuclear 

anomalies at doses reaching the limit dose: 5000 mg/kg 

(2500 mg/kg/day X 2). 

UDS study: DNA damage and 

repair in vitro in rat hepatocytes 

40271955 (1984; 1986) 

(supplement) 

Acceptable 

Rat hepatocytes exposed to test substance at 0, 2, 10, 50, 

250 μg/ml. Negative up to limit of solubility (250 μg/ml) 

for inducing UDS. 

870.7485 

Metabolism and 

pharmacokinetics 

40728319 (1988) 

Acceptable/guideline 

Metabolism of [(U-14C)Phenyl]triasulfuron was studied 

in 5/sex Wistar rats. Material administered orally as a 

single low dose (0.5 mg/kg) & high dose (300 mg/kg), 

single low dose after daily doses of unlabeled material 

for 14 days (0.5 mg/kg/day) or single i.v. dose of 0.5 

mg/kg. 92-109% of dose recovered within 96 hours: 74-

99% in urine & 2-14% in feces. Elimination rates after 

repeated oral dosing faster than after single dose. Residue 

levels in tissue < 0.1%. Levels in tissues higher after 

single high dose than after single low dose. Even after 

repeated administration at low dose, no radioactivity 

retained by animals. Metabolite patterns in urine, fecal 

and liver extracts show mainly parent compound. Variety 

of minor metabolites: 12 urinary (6.6-8.1%), 10 fecal 

(1.2-2.9%) of the administered radioactivity, 

respectively. No significant differences in metabolite 

patterns between sexes. 
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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. 

 
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Appendix C. Occupational Non-cancer Algorithms 

Occupational Non-cancer Handler Algorithms 

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

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 label (lb ai A or lb ai/gal), and 

A = area treated or amount handled (e.g., A/day, 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 and/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 inhalation dose 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 

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

following formulas: 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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

* ቀ4.54E8 ug

lbቁ * ൬2.47E-8

A

cm2൰

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/or inhalation), 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). 
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Appendix D. Dietary Exposure/Risk Modeling Input and Output 

DEEM-FCID Chronic Inputs File 

Filename: C:\Users\jlangsda\Documents\Chemicals\SUs\Triasulfuron\Dietary 

Assessment\Triasulfuron_Chronic.r08 

Chemical: Triasulfuron 

RfD(Chronic): .01 mg/kg bw/day NOEL(Chronic): 0 mg/kg bw/day 

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

Date created/last modified: 05-07-2015/10:31:54 Program ver. 3.16, 03-08-d 

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

 EPA Crop Def Res Adj.Factors Comment 

 Code Grp Commodity Name (ppm) #1 #2 

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

1500025000 15 Barley, pearled barley 0.020000 1.000 1.000 

1500025001 15 Barley, pearled barley-babyfood 0.020000 1.000 1.000 

1500026000 15 Barley, flour 0.020000 1.000 1.000 

1500026001 15 Barley, flour-babyfood 0.020000 1.000 1.000 

1500027000 15 Barley, bran 0.020000 1.000 1.000 

1500381000 15 Triticale, flour 0.020000 1.000 1.000 

1500381001 15 Triticale, flour-babyfood 0.020000 1.000 1.000 

1500401000 15 Wheat, grain 0.020000 1.000 1.000 

1500401001 15 Wheat, grain-babyfood 0.020000 1.000 1.000 

1500402000 15 Wheat, flour 0.020000 1.000 1.000 

1500402001 15 Wheat, flour-babyfood 0.020000 1.000 1.000 

1500403000 15 Wheat, germ 0.020000 1.000 1.000 

1500404000 15 Wheat, bran 0.020000 1.000 1.000 

3100044000 31 Beef, meat 0.100000 1.000 1.000 

3100044001 31 Beef, meat-babyfood 0.100000 1.000 1.000 

3100045000 31 Beef, meat, dried 0.100000 1.920 1.000 

3100046000 31 Beef, meat byproducts 0.100000 1.000 1.000 

3100046001 31 Beef, meat byproducts-babyfood 0.100000 1.000 1.000 

3100047000 31 Beef, fat 0.100000 1.000 1.000 

3100047001 31 Beef, fat-babyfood 0.100000 1.000 1.000 

3100048000 31 Beef, kidney 0.500000 1.000 1.000 

3100049000 31 Beef, liver 0.100000 1.000 1.000 

3100049001 31 Beef, liver-babyfood 0.100000 1.000 1.000 

3200169000 32 Goat, meat 0.100000 1.000 1.000 

3200170000 32 Goat, meat byproducts 0.100000 1.000 1.000 

3200171000 32 Goat, fat 0.100000 1.000 1.000 

3200172000 32 Goat, kidney 0.500000 1.000 1.000 

3200173000 32 Goat, liver 0.100000 1.000 1.000 

3300189000 33 Horse, meat 0.100000 1.000 1.000 

3400290000 34 Pork, meat 0.100000 1.000 1.000 

3400290001 34 Pork, meat-babyfood 0.100000 1.000 1.000 

3400291000 34 Pork, skin 0.100000 1.000 1.000 

3400292000 34 Pork, meat byproducts 0.100000 1.000 1.000 

3400292001 34 Pork, meat byproducts-babyfood 0.100000 1.000 1.000 

3400293000 34 Pork, fat 0.100000 1.000 1.000 

3400293001 34 Pork, fat-babyfood 0.100000 1.000 1.000 

3400294000 34 Pork, kidney 0.500000 1.000 1.000 

3400295000 34 Pork, liver 0.100000 1.000 1.000 

3500339000 35 Sheep, meat 0.100000 1.000 1.000 

3500339001 35 Sheep, meat-babyfood 0.100000 1.000 1.000 

3500340000 35 Sheep, meat byproducts 0.100000 1.000 1.000 

3500341000 35 Sheep, fat 0.100000 1.000 1.000 

3500341001 35 Sheep, fat-babyfood 0.100000 1.000 1.000 

3500342000 35 Sheep, kidney 0.500000 1.000 1.000 

3500343000 35 Sheep, liver 0.100000 1.000 1.000 

3600222000 36 Milk, fat 0.020000 1.000 1.000 

3600222001 36 Milk, fat-baby food/infant formu 0.020000 1.000 1.000 

3600223000 36 Milk, nonfat solids 0.020000 1.000 1.000 

3600223001 36 Milk, nonfat solids-baby food/in 0.020000 1.000 1.000 

3600224000 36 Milk, water 0.020000 1.000 1.000 

3600224001 36 Milk, water-babyfood/infant form 0.020000 1.000 1.000 

3600225001 36 Milk, sugar (lactose)-baby food/ 0.020000 1.000 1.000 

3800221000 38 Meat, game 0.100000 1.000 1.000 
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3900312000 39 Rabbit, meat 0.100000 1.000 1.000 

8601000000 86A Water, direct, all sources 0.019000 1.000 1.000 

8602000000 86B Water, indirect, all sources 0.019000 1.000 1.000 

DEEM-FCID Chronic Results File

U.S. EPA Ver. 3.16, 03-08-d 

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

Residue file name: C:\Users\jlangsda\Documents\Chemicals\SUs\Triasulfuron\Dietary 

Assessment\Triasulfuron_Chronic.r08 

 Adjustment factor #2 used. 

Analysis Date 05-07-2015/10:33:20 Residue file dated: 05-07-2015/10:31:54 

Reference dose (RfD, Chronic) = .01 mg/kg bw/day 

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

 Total exposure by population subgroup 

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

 Total Exposure 

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

 Population mg/kg Percent of 

 Subgroup body wt/day Rfd 

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

Total US Population 0.000677 6.8% 

Hispanic 0.000706 7.1% 

Non-Hisp-White 0.000684 6.8% 

Non-Hisp-Black 0.000574 5.7% 

Non-Hisp-Other 0.000749 7.5% 

Nursing Infants 0.000461 4.6% 

Non-Nursing Infants 0.001718 17.2% 

Female 13+ PREG 0.000595 6.0% 

Children 1-6 0.001389 13.9% 

Children 7-12 0.000778 7.8% 

Male 13-19 0.000573 5.7% 

Female 13-19/NP 0.000522 5.2% 

Male 20+ 0.000592 5.9% 

Female 20+/NP 0.000587 5.9% 

Seniors 55+ 0.000561 5.6% 

All Infants 0.001330 13.3% 

Female 13-50 0.000580 5.8% 

Children 1-2 0.001716 17.2% 

Children 3-5 0.001250 12.5% 

Children 6-12 0.000824 8.2% 

Youth 13-19 0.000547 5.5% 

Adults 20-49 0.000604 6.0% 

Adults 50-99 0.000570 5.7% 

Female 13-49 0.000581 5.8% 

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

 
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Appendix E. Nomenclature and Physical/Chemical Properties 

Table E.1. Triasufluron Nomenclature.

Compound 

Common name Triasulfuron 

Company experimental name Not Applicable 

IUPAC name 1-[2-(2-chloroethoxy)phenylsulfonyl] -3 - (4-methoxy-6- methyl-1,3,5-triazin-2-

yl)urea, [3-(6-methoxy-4-methyl-1,3,5-triazin-2-yl)-1-(2-(2-

chloroethoxy)phenylsulfonyl)urea] 

CAS name 2-(2-chloroethoxy)-N-[[(4-methoxy-6-methyl-=1,3,5-triazin-2-

yl)amino]carbonyl], benzenesulfonamide 

CAS registry number 82097- 50 - 5 

Table E.2. Physicochemical Properties of the Technical Grade Triasulfuron.

Parameter Value Reference 

Melting point/range 178°C/ Not Applicable Material 

Safety 

Data 

Sheet 

pH 6.0 -7.0 

Density 0.50 – 70.0 g/cm3 

Water solubility (mg/L) pH 5: 32 mg/l at 25 °C 

pH 7: 815 mg/l at 25 °C 

pH 8.4: 13500 mg/l at 25 °C 

Solvent solubility (mg/L) at room 

temperature 

N hexane 0.04 mg/l 

toluene 300 mg/l 

acetone 14 g/l 

n octanol 0.13 g/l 

ethyl acetate 4.3g/l 

dichloromethane 36g/l 

Vapor pressure < 1.5 x 10(-8) mmHg @ 25°C (77°F) 

Dissociation constant, pKa 4.64 

Octanol/water partition coefficient pH 5: log Pow =1.1 (at 25 °C) 

pH 6.9: log Pow = - 0.59 

pH 9.0: log Pow = - 1.8 

UV/visible absorption 

L mol-1 cm-1

223.4 nm ε 26051 l . mol-1. cm-1 (purity 99.5 %) 

282.8 nm ε 3415 l .mol-1.cm-1

shoulder between 240nm - 250nm 

no absorption after 340 nm 
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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 it may directly contact. They can also deposit on 

surfaces where contact with residues can eventually lead to exposures (e.g., children playing on 

lawns where residues have deposited next to treated fields). The potential risk estimates from 

these residues can be calculated using drift modeling coupled with methods employed for 

residential risk assessments for turf products. 

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

assessing 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 exposure scenario. 

Aside from the predicted residues available for transfer, the routes of exposure and assessment 

methodology is 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 triasulfuron. 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. 

Exposures were considered for 50 feet wide lawns where the nearest side of the property was 

directly adjoining the treated field (at field edge) and at varied distances up to 300 feet 

downwind of a treated field. 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 

recently revised (2012) Standard Operating Procedures For Residential Risk Assessment 

(SOPs). 

 

A screening approach was developed for situations where specific label guidance for 

application parameters is not available.9,10 AgDrift® is appropriate for use only when applications 

are made by aircraft, airblast 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. 

In all cases, each scenario is to be evaluated unless it is not plausible based on the anticipated use 

pattern (e.g., herbicides are 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 

 

9

http://www.agdrift.com/ 

10 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. 
Triasulfuron Human-Health Risk Assessment DP No. 425587 

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management options additional spray drift deposition fractions were also considered. These drift 

estimates represent plausible options based on the available pesticide labels. 

Appendix G. Analytical Standards Summary 

Analytical reference standards for triasulfuron are currently available in EPA’s National 

Pesticide Standards Repository (NPSR) and have an expiration date of 6/30/2017 (email 

communication between G. Verdin and J. Van Alstine, 5/7/2015). The registrant is required to 

maintain reasonable amounts of the reference standards for triasulfuron in the NPSR as long as 

tolerances remain published in 40 CFR §180.459. 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. Material Safety Data Sheets (MSDSs) must accompany all 

analytical standards as specified by the Occupational Safety and Health Administration (OSHA) 

in 29CFR §1910.1200.