UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

MEMORANDUM

DATE: August 30, 2011

SUBJECT: MetsulfuronHuman Health Assessments

PC Code: 122010

MRID No.: NA

Petition No.: NA

Assessment Type: Single Chemical/ 

Aggregate

TXR No.: NA

FROM: Charles Smith

Sheila Piper, Senior Chemist

Monica Hawkins, Ph.D., M.P.H., Environmental Health Scientist

Steven Dapson

Risk Assessment

Health Effects Division (7509P)

THROUGH: Felecia Fort, Branch Chief

Risk Assessment

Health Effects Division (7509P)

TO: Jill Bloom, Chemical Review Manager

Risk Management and 

Pesticide Re-E

Executive Summary

The Health Effects Division (HED) 

evaluated the status of the human health assessment for the 

to determine the scope of work necessary to support Registration Review.

methyl is registered for use on a 

hardwoods, on industrial sites, and on turf

iodosulfuron-methyl (currently registered only on corn) in water. 

Alimentarius Commission and Mexico have not established maximum residue limits 

(MRLs) for metsulfuron-methyl. Canada has established MRLs for some plant a

livestock commodities. The most recent 

methyl were completed in 200

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION

2011

-Methyl: Registration Review Scoping Document for 

Health Assessments.

DP Barcode: D389257

Registration No.: NA

Regulatory Action: Registration Review

Single Chemical/ Reregistration Case No.: 7205

CAS No.: 74223-64-6

Charles Smith, Senior Environmental Scientist/Risk Assessor

Sheila Piper, Senior Chemist

Monica Hawkins, Ph.D., M.P.H., Environmental Health Scientist

Steven Dapson, PhD, Senior Toxicologist

Risk Assessment Branch VI

Health Effects Division (7509P)

Branch Chief

Risk Assessment Branch VI

Health Effects Division (7509P)

Chemical Review Manager

Risk Management and Implementation Branch II

Evaluation Division (7508P)

The Health Effects Division (HED) Metsulfuron-Methyl Registration Review Team has 

evaluated the status of the human health assessment for the herbicide metsulfuron

to determine the scope of work necessary to support Registration Review. Metsulfuron

registered for use on a number of food and feed crops, on conifers and 

hardwoods, on industrial sites, and on turf. It is also the principal degradate of 

methyl (currently registered only on corn) in water. The Codex 

Alimentarius Commission and Mexico have not established maximum residue limits 

methyl. Canada has established MRLs for some plant a

The most recent exposure and risk assessments for metsulfuron

2002 (M. Collantes, D282214, 6/19/02 and W. Cutchin

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION

egistration Review Scoping Document for 

Registration Review

Monica Hawkins, Ph.D., M.P.H., Environmental Health Scientist

Registration Review Team has 

metsulfuron-methyl

Metsulfuron-

, on conifers and 

principal degradate of 

The Codex 

Alimentarius Commission and Mexico have not established maximum residue limits 

methyl. Canada has established MRLs for some plant and 

metsulfuronCutchin, 
Page 2 of 21

D281907, 6/26/2002). Based on the current use profile, exposures can be expected to 

occur via the dietary (food and drinking water), residential (handler and post-application),

and occupational (handler and post-application) routes for metsulfuron-methyl.

The toxicity database for metsulfuron-methyl is nearly complete at the present time with 

the exception of a neurotoxicity battery (i.e., acute and subchronic neurotoxicity) and an 

immunotoxicity study. A 28-day inhalation study was previously required as a condition 

of registration for the use of metsulfuron-methyl on sorghum (W. Cutchin, D281907, 

6/26/2002). This study has not been submitted to the Agency as this time. The Agency

has classified metsulfuron-methyl as “not likely to be carcinogenic to humans” based on 

the results of carcinogenicity studies in rats and mice. Metsulfuron-methyl has low acute 

toxicity by oral, dermal, and inhalation routes of exposure but it is classified as a severe 

eye irritant. No reproductive or developmental effects were observed in metsulfuronmethyl toxicity studies using rats and rabbits. Upon receipt of the required toxicity

studies, HED will reevaluate the points of departure and uncertainty factors for the 

dietary and occupational exposure assessments.

The existing residue chemistry database for metsulfuron-methyl is adequate for risk 

assessment purposes. The qualitative nature of the residue(s) of metsulfuron-methyl in 

plants and animals has been adequately identified/characterized and is understood. The 

current tolerance expression as listed in the 40 CFR§180.428(a) has not been updated to 

reflect current HED policies and thus will need to be revised during the registration 

review process.

The dietary exposure database is adequate to support the existing registrations. New 

chronic dietary exposure and risk assessments will be required during registration review, 

which incorporate current consumption information, updated residue values and percent 

crop treated information while directly incorporating drinking water values into the 

assessment. Further, an acute dietary assessment may need to be completed if new 

toxicity data are identified that indicate the need for an acute dietary risk assessment.

The residential exposure database is adequate to support the registration review process 

for metsulfuron-methyl. In the 2002 exposure assessment, all of the non-cancer 

residential handler and postapplication risk estimates were below the Agency’s level of 

concern. No new residential handler or postapplication worker studies are needed at this 

time. An updated residential exposure assessment may be required under registration 

review based upon revisions to HED’s Residential SOPs which was reviewed by the 

Scientific Advisory Panel (SAP) in October 2009. An updated assessment may also be 

required if new data are identified which impact exposure estimates, new points of 

departure, a revised FQPA SF, or revisions to exposure policies and procedures are made.

The occupational exposure database is adequate to support the registration review process 

for metsulfuron-methyl. In the 2002 exposure assessment, all of the non-cancer 

occupational handler and postapplication risk estimates were below the Agency’s level of 

concern. No new occupational handler or postapplication worker studies are needed at 

this time. Revised occupational handler and postapplication assessments may be needed 

if toxicological endpoints change, other new data are received by EPA, or other 

parameters are modified, such as changes to Standard Operating Procedures or default 
Page 3 of 21

exposure assessment assumptions. Determination of the appropriate REI for 

metsulfuron-methyl should be performed during registration review.

Introduction

Metsulfuron-methyl is a herbicide used to control a variety of annual grasses and 

broadleaf weeds. It is also the principal degradate of iodosulfuron-methyl (currently 

registered only on corn) in water. HED has reviewed the most recent exposure and risk 

assessments for metsulfuron-methyl, as well as toxicity data, exposure and usage 

databases, and the latest Agency science policy and risk assessment methodologies to 

determine if sufficient data are available and if updates are needed to support registration 

review. Additionally, the team conducted a screening-level literature search for any

information that would aid in assessing human health risks to metsulfuron-methyl.

Chemical Identity

Metsulfuron-methyl is a sulfonylurea herbicide registered on a number of food and feed 

crops, on conifers and hardwoods, on industrial sites, and on turf. Sulfonylurea 

compounds inhibit acetolactate synthase (ALS) which is involved in cell division at the 

root tip. Registered products containing metsulfuron-methyl include water dispersable 

granule (WDG)/dry flowable (DF) formulations. These formulations may be applied preor post-emergence using aerial and ground equipment. 

The current tolerance expression as listed in the 40 CFR §180.416 has not been updated 

to reflect current HED polices. The revised tolerance expression should be as follows: 

Tolerances are established for the residues of the herbicide metsulfuron-methyl, including 

its metabolites and degradates, in or on plant commodities. Compliance with the 

tolerance levels is to be determined by measuring only the sum of metsulfuron-methyl 

(methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl] 

benzoate) and its metabolite, methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-

yl)amino]carbonyl]amino]sulfonyl]-4-(beta-D-glycopyranosyl)benzoate (Metabolite A) 

and methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-

yl)amino]carbonyl]amino]sulfonyl]-4-hydroxybenzoate (Metabolite A1), calculated as 

the stoichiometric equivalent of metsulfuron-methyl, in or on the commodity.

Tolerances are established for the residues of the herbicide metsulfuron-methyl, including 

its metabolites and degradates, in or on livestock commodities. Compliance with the 

tolerance levels is to be determined by measuring only metsulfuron-methyl (methyl 2-

[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl] benzoate), in 

or on the commodity.

The chemical structure and nomenclature of metsulfuron-methyl and the physicochemical 

properties of technical grade metsulfuron-methyl are presented in Tables 1 and 2.

Hazard Identification/Toxicology

The toxicity database for metsulfuron-methyl is nearly complete at the present time with 

the exception of a neurotoxicity battery (i.e., acute and subchronic neurotoxicity) and an 

immunotoxicity study (see Table 3A). The acute database indicates that metsulfuronmethyl has low acute toxicity by oral, dermal, and inhalation routes of exposure (see 

Table 3B). It is a severe eye irritant (Category 1) but does not cause primary dermal 

irritation. Metsulfuron-methyl is not a skin sensitizer.
Page 4 of 21

For a summary of the subchronic and chronic toxicity profile, see Table 3C. In

mammals, metsulfuron methyl exhibited generalized, nonspecific toxicity and did not 

appear to have specific target organ toxicity. Rats appear to be the most sensitive species

tested. The HED Hazard Identification Assessment Review Committee (HIARC), in 

accordance with the 1999 Draft Guidance for Carcinogenic Risk Assessment, classified 

metsulfuron methyl as “not likely to be carcinogenic to humans.” This is based on the 

lack of evidence of carcinogenicity in mice and rats, no evidence of mutagenicity in 

several acceptable studies, and the non-carcinogenic potential of structurally related 

compounds.

Metsulfuron-methyl is well absorbed regardless of dose or treatment regimen

(single gavage dose alone or after repeated dietary feeding). The primary route of 

excretion is via the urine (71-95%) followed by fecal elimination (4.8-13.3%) and levels 

remaining in the tissues are negligible.

HED has fully evaluated the toxicity database of metsulfuron methyl with respect to the 

potential for special sensitivity of infants and children, and concludes that there is no 

concern for pre- and postnatal susceptibility for infants and children. The FQPA safety

factor has been reduced to 1X because (1) the toxicity database is complete and adequate 

to characterize potential pre- and postnatal risk for infants and children; and (2) no 

reproductive or developmental effects were observed in rats and rabbits. 

In accordance with the revised 40 CFR Part 158 data requirements, a neurotoxicity

battery (i.e., acute and subchronic neurotoxicity) is required for all food and non-food use 

chemicals. Although the available metsulfuron-methyl toxicity studies showed no 

neurotoxicity, these studies do not use optimal methods to evaluate the nervous tissue 

structure and function. Consequently, the neurotoxicity studies are required to detect and 

more fully characterize the potential neurotoxic effects of metsulfuron-methyl. 

An immunotoxicity study is also required as a part of the new data requirements in 40 

CFR Part 158 for conventional pesticide registration. Because the immune system is 

highly complex, studies not specifically conducted to assess immunotoxic endpoints are 

inadequate to characterize a pesticide’s potential immunotoxicity. While data from 

hematology, lymphoid organ weights, and histopathology in routine chronic or subchronic toxicity studies may offer useful information on potential immunotoxic effects, 

these endpoints alone are insufficient to predict immunotoxicity. Consequently, the 

immunotoxicity study is required to detect and more fully characterize the potential 

immunotoxic effects of metsulfuron-methyl. 

Once these studies are made available to the Agency, they will be reviewed and HED will 

reevaluate the points of departure and uncertainty factors used in risk assessment. In the 

absence of the required studies, EPA may use a database uncertainty factor of up to 10X.

For a summary of the relevant toxicological endpoints used in risk assessment, please see 

Tables 3D (dietary endpoints) and 3E (occupational endpoints).
Page 5 of 21

Endocrine Disruption

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 

registration review, EPA will review these data and select the most sensitive endpoints 

for relevant risk assessment scenarios from the existing hazard database. However, as 

required by FFDCA section 408(p), metsulfuron-methyl 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. 

Metsulfuron-methyl is not among the group of 58 pesticide active ingredients on the 

initial list to be screened under the EDSP. Accordingly, as part of registration review, 

EPA will issue future EDSP orders/data call-ins, requiring the submission of EDSP 

screening assays for metsulfuron-methyl. For further information on the status of the 

EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test 

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

http://www.epa.gov/endo/.

Conclusions for Hazard Identification/Toxicology

The toxicity database for metsulfuron-methyl is nearly complete at the present time with 

the exception of a neurotoxicity battery (i.e., acute and subchronic neurotoxicity) and an 

immunotoxicity study. A 28-day inhalation study was previously required as a condition 

of registration for the use of metsulfuron-methyl on sorghum (W. Cutchin, D281907, 

6/26/2002). This study has not been submitted to the Agency as this time.

Residue Chemistry

The HED Metabolism Assessment Review Committee (MARC) determined that the 

residue of concern for plants is metsulfuron-methyl and its metabolite, methyl 2-[[[[(4-
Page 6 of 21

methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]-4-(beta-Dglycopyranosyl)benzoate (Metabolite A) and methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-

triazin-2-yl)amino]carbonyl]amino]sulfonyl]-4-hydroxybenzoate (Metabolite A1) 

(MARC, D279786, 12/17/01). The residue of concern for livestock is metsulfuron 

methyl. The current tolerance expression as listed in the 40 CFR§180.428(a) has not 

been updated to reflect current HED policies.

Adequate analytical methods (HPLC/UV) exist for data collection and tolerance 

enforcement. PAM Vol. II lists Methods I and III which are respectively capable of 

determining residues of metsulfuron-methyl and the combined residues Metabolites A 

and A1 in/on wheat RACs. Method II determines metsulfuron methyl in ruminant tissues 

and milk. No additional residue chemistry data are required to support the existing uses 

of metsulfuron-methyl.

Dietary Exposure and Risks

An unrefined chronic dietary (food only) risk assessment was completed for a Section 3 

use on grain sorghum (W.Cutchin, D281906, 4/3/02). HED concluded that there is a 

reasonable certainty that no harm will result to the general population, infants and 

children from chronic dietary exposure to metsulfuron-methyl. Acute and cancer dietary

exposure estimates are not required for metsulfuron-methyl.

Drinking Water

Metsulfuron-methyl appears not to be persistent and has high mobility in soils. The 

MARC concluded that only the parent compound needs to be included in the drinking 

water assessment. The Environmental Fate and Effects Division (EFED) provided 

drinking water numbers for use in dietary risk assessments (S.Termes, D279400, 1/9/02) 

in association with the use on sorghum. The FIFRA Index Reservoir Screening Tool 

(FIRST) was used for estimating the concentration of metsulfuron-methyl as a metabolite 

of iodosulfuron-methyl, since FIRST has been used in estimating the drinking water 

values for the corn use with the proposed label for iodosulfuron-methyl. The Screening 

Concentration in Groundwater (SCI-GROW) model was utilized to estimate the 

concentration of metsulfuron in ground water as a result of application on turf. 

In the 2002 HED risk assessment, risks from potential exposure to metsulfuron-methyl in 

drinking water from all sources were evaluated by comparing these modeled surface and 

ground water estimates against calculated drinking water levels of comparison 

(DWLOCs). This assessment indicated that the estimated drinking water concentration 

(EDWC) estimates for metsulfuron-methyl residues in surface and ground water did not 

exceed the Agency’s estimated chronic DWLOC value. 

Acute Dietary Exposure and Risk (Food and Drinking Water) 

In the 2002 HED risk assessment, an acute dietary assessment was not required for 

metsulfuron methyl because an appropriate acute dietary endpoint was not available.

Chronic Exposure and Risk (Food and Drinking Water)

In the 2002 HED risk assessment, an unrefined, chronic dietary exposure assessment was 

performed using tolerance level residues, default DEEM processing factors, and 

assuming 100% crop treated. This assessment concluded that the chronic dietary
Page 7 of 21

exposure estimates did not exceed HED’s level of concern (<100% cPAD) for any 

population subgroup.

Conclusions for Dietary Exposure and Risk

The dietary exposure database is adequate to support the existing registrations. However, 

it will be necessary for HED to conduct a new dietary exposure assessment for 

metsulfuron-methyl including new and updated information and policies, which includes 

directly incorporating drinking water estimates into the dietary assessment. The revised 

assessment should include updated consumption information and utilize the newest 

version of DEEM-FCID. Further, an acute dietary assessment may need to be completed 

if new toxicity data are identified that indicate the need for an acute dietary risk 

assessment.

Residential Exposure and Risks

Metsulfuron-methyl is registered for use on residential lawns, recreational areas (i.e., 

parks and sports fields), and on golf courses. Due to this use profile, adult residential 

homeowners may experience exposure to metsulfuron-methyl during application of the 

chemical (i.e., residential handler exposures). Adults and children may experience 

exposure to metsulfuron-methyl when contacting previously treated areas (i.e., residential 

postapplication exposure).

The most recent metsulfuron occupational and residential exposure assessment (M. 

Collantes, D282214, 6/19/02) addressed the potential residential handler exposures to 

adults and the potential residential postapplication exposures to adults and children.

Residential Handler

The Agency has determined that there is potential for residential handlers to be exposed 

to metsulfuron-methyl during the following activities: 

 mixing/loading/applying water dispersable granules/dry flowables with low 

pressure handwand equipment;

 mixing/loading/applying water dispersable granules/dry flowables with backpack 

sprayer equipment;

 mixing/loading/applying water dispersable granules/dry flowables with hose end 

sprayer equipment; and

 mixing/loading/applying water dispersable granules/dry flowables with sprinkler 

can equipment.

The 2002 exposure assessment assessed two residential handler scenarios (i.e., low 

pressure handwand sprayer and hose end sprayer). Residential handler exposures were 

estimated using exposure data from the Pesticide Handler Exposure Database (PHED) 

and the Outdoor Residential Exposure Task Force (ORETF).

The non-cancer handler risk estimates presented in the 2002 exposure assessment 

indicate that all of the residential handler scenarios resulted in risks that did not exceed 

HED’s level of concern (i.e., MOEs > 100). 
Page 8 of 21

Residential Post-Application 

The Agency has determined that there is potential for residential postapplication exposure 

to children from use of metsulfuron-methyl on residential lawns and to adults from use of 

metsulfuron-methyl on residential lawns and golf courses.

In the 2002 exposure assessment, a number of postapplication residential exposure 

scenarios were assessed for adults and children. These scenarios included playing on a 

treated lawn (adults and children) and golfing on treated turf (adults only). For adults, 

dermal exposures were assessed for all scenarios while for children, dermal and nondietary ingestion exposures were assessed for all scenarios. Post-application exposures 

were calculated using the HED Draft SOP’s for Residential Exposure Assessments 

(12/18/97). All scenarios for both adults and children had MOEs that did not exceed 

HED’s level of concern (MOE >=100).

Residential bystander inhalation exposures resulting from off-site transport (e.g., spray

drift or volatilization) may occur as a result of applications of metsulfuron-methyl. The 

Agency is in the process of evaluating these types of exposures and may, as appropriate, 

develop policies and procedures to identify the need for and, subsequently, the way to 

incorporate post-application inhalation exposure into the Agency’s risk assessments. The 

need for a bystander inhalation risk assessment for metsulfuron-methyl should be 

examined during registration review.

Conclusions for Residential Exposure and Risk Assessment

The residential exposure database is adequate to support the registration review process 

for metsulfuron-methyl. An updated residential exposure assessment may be required 

under registration review based upon revisions to HED’s Residential SOPs which were

reviewed by the Scientific Advisory Panel (SAP) in October 2009. An updated 

assessment may also be required if new data are identified which impact exposure 

estimates, new points of departure, a revised FQPA SF, or revisions to exposure policies 

and procedures are made.

Aggregate Risk Assessment

In the 2002 metsulfuron-methyl risk assessment, HED determined that short-term, 

intermediate-term, and chronic aggregate risk assessments were appropriate. The chronic 

aggregate assessment was equivalent to the chronic dietary risk assessment. The chronic 

dietary risk estimates for the general population and all population subgroups were not of 

concern to HED.

For the short- and intermediate-term aggregate assessment, HED combined residential 

exposures from turf with the chronic dietary exposures. HED concluded that the 

combined residues of metsulfuron-methyl from food and other potential residential 

exposures do not result in short- and intermediate-term aggregate risks of concern. 

As noted above in the dietary section, the 2002 risk assessment did not directly

incorporate drinking water into the dietary assessment and thus a new chronic dietary

assessment is required during registration review. As a result, during registration review, 

new short-term, intermediate-term, and chronic aggregate risk assessments are required.
Page 9 of 21

Conclusions for Aggregate Exposure and Risk Assessment

Updated aggregate exposure and risk assessments will be required under registration 

review based on the need for directly incorporating drinking water into the dietary

exposure estimates.

Occupational Exposure and Risks

Metsulfuron-methyl is registered as a water dispersable granule (WDG)/dry flowable 

(DF) for occupational use on a number of agricultural field crops, on conifers and 

hardwoods, on industrial sites, and on turf. It may be applied pre- or post-emergence 

using aerial and ground equipment. 

Occupational Handlers

The Agency has determined that there is potential for occupational handlers to be 

exposed to metsulfuron-methyl during the following activities: 

 mixing and loading of water dispersable granule (WDG)/dry flowable (DF) to 

support groundboom and aerial equipment;

 applying sprays with groundboom and aerial equipment;

 mixing/loading/applying water dispersable granules/dryflowables with low 

pressure handwand equipment, backpack sprayer equipment, and turfgun 

equipment; and 

 flagging for aerial sprays.

The 2002 exposure assessment assessed a number of occupational handler scenarios. 

Occupational handler exposures were estimated using exposure data from PHED and 

ORETF.

The non-cancer handler risk estimates presented in the 2002 exposure assessment 

indicate that all of the occupational handler scenarios resulted in risks that did not exceed 

HED’s level of concern (i.e., MOEs > 100) at some level of risk mitigation. 

Occupational Postapplication

The Agency has determined that there is the potential for occupational postapplication 

exposures to individuals entering areas treated with metsulfuron-methyl including, 

agricultural fields, conifers and hardwood forests, industrial sites, and turf.

The 2002 exposure assessment assessed the occupational postapplication exposure 

resulting from applications of metsulfuron-methyl to sorghum, conifer and hardwoods, 

industrial sites, and turf. It did not assess all of the potential postapplication exposures 

that could result from the other agricultural uses of metsulfuron-methyl (e.g., barley, 

sugarcane, and wheat). The 2002 assessment utilized surrogate transfer coefficient data 

from the Agricultural Reentry Task Force (ARTF) database. For all postapplication 

exposure scenarios, non-cancer risks do not exceed HED’s level of concern (i.e., MOEs > 

100) on the day of application. 

Metsulfuron-methyl is classified as Toxicity Category I for primary eye irritation and 

thus should have a Restricted Entry Interval (REI) of 48 hours based on the Worker 
Page 10 of 21

Protection Standard. Current metsulfuron-methyl labels appear to carry either a 4 or 12 

hour REI so this issue should be revisited during registration review.

Conclusions

The occupational exposure database is adequate to support the registration review process 

for metsulfuron-methyl. No new handler or postapplication worker studies are needed at 

this time. Revised occupational handler and postapplication assessments may be needed 

if toxicological endpoints change, other new data are received by EPA, or other 

parameters are modified, such as changes to Standard Operating Procedures or default 

exposure assessment assumptions. Determination of the appropriate REI for 

metsulfuron-methyl should be performed during registration review.

Human Studies

Metsulfuron-methyl risk assessments rely in part on data from studies in which adult 

human subjects were intentionally exposed to a pesticide or other chemical. Studies such 

as PHED, ORETF, and ARTF have been reviewed by the Agency and found on the basis 

of available evidence to have been neither fundamentally unethical nor significantly

deficient relative to standards of ethical research conduct prevailing when they were 

conducted. There is no barrier in EPA's "Protection of Human Subjects" regulation to 

reliance on these studies.

Public Health and Pesticide Epidemiology Data

An updated review of metsulfuron-methyl incident reports was recently prepared by HED 

(K. Oo, D389637, 05/25/2011). For this evaluation, the OPP Incident Data System (IDS) 

was consulted for pesticide incident data on the active ingredient metsulfuron-methyl. 

The IDS includes reports of alleged human health incidents from various sources, 

including mandatory Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) 

Section 6 (a) (2) reports from registrants, other federal and state health and environmental 

agencies and individual consumers. IDS contain reports from across the U.S. and most 

incidents have all relevant product information recorded. Reports submitted to the IDS

represent anecdotal reports or allegations only, unless otherwise stated in the report. IDS 

records incidents resulting in higher severity outcomes in more detail, in a module called 

the Main IDS module. This system stores incident data for death, major and moderate 

incidents, and it includes more details about the location, date and nature of the incident.

For IDS aggregate summaries, from January 1, 2006 to March 31, 2011, there are 37

cases reported for metsulfuron-methyl. Because it falls within the categories reported as 

counts (which includes minor, unknown or no effects), there is no unique report that 

provides details about the incident and single chemical incidents are not distinguished 

from multiple chemical incidents; however, a high frequency of incidents indicates there 

is a high potential for exposure and vice versa. For the Main IDS, from January 1, 2006

to March 31, 2011, there are 12 cases reported that involve the active ingredient 

metsulfuron-methyl. However, there are no incidents reported for single chemical 

metsulfuron-methyl only in the database. 

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 Agency will continue to 
Page 11 of 21

monitor the incident information and if a concern is triggered, additional analysis will be 

included during registration review.

Tolerance Assessment and International Harmonization

Tolerances are established under 40 CFR§180.428(a) for residues of the herbicide 

metsulfuron-methyl, including its metabolites and degradates, in or on a variety of plant 

commodities as well as in or on livestock commodities (see Table 4). The Codex 

Alimentarius Commission and Mexico have not established maximum residue limits 

(MRLs) for metsulfuron-methyl. Canada has established MRLs for some plant and 

livestock commodities. Any metsulfruon-methyl tolerances reassessed during the 

registration review process will be considered for possible harmonization with 

international MRLs should they be established.

Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, will be

considered in the registration review 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://www.epa.gov/compliance/resources/policies/ej/exec_order_12898.pdf. The Office 

of Pesticide Programs (OPP) typically considers the highest potential exposures from the 

legal use of a pesticide when conducting human health risk assessments, including, but 

not limited to, people who obtain drinking water from sources near agricultural areas, the 

variability of diets within the U.S., and people who may be exposed when harvesting 

crops. Should these high exposures indicate potential risks of concern, OPP will further 

refine the risk assessments to ensure that the risk estimates are based on the best available 

information.

Cumulative Risk Assessment

At this time, EPA does not have available data to determine whether metsulfuron-methyl

has a common mechanism of toxicity with other substances. EPA has not made a 

common mechanism of toxicity finding as to metsulfuron-methyl and any other 

substances, and metsulfuron-methyl does not appear to produce a toxic metabolite 

produced by other substances which have tolerances in the U.S. Therefore, EPA has not 

assumed that metsulfuron-methyl has a common mechanism of toxicity with other 

substances.

Data Requirements

HED does not anticipate that additional residue chemistry, toxicology or 

occupational/residential exposure data will be required for the metsulfuron-methyl

registration review process, with the exception of the following studies listed below:

 Immunotoxicity Study (OPPTS 870.7800)

 Neurotoxicity Battery (Acute and Subchronic Studies) (OPPTS 870.6200)

The following study was previously required as a condition of registration for the use of 

metsulfuron-methyl on sorghum. To date, the Agency has not received this study.

 28-Day Inhalation Study (OPPTS 870.3465) - The 90-day study protocol should 

be followed using an exposure duration of 28 days.
Page 12 of 21

Table 1. Metsulfuron-methyl Nomenclature

Compound

Chemical Structure

S

N

H

N

H

O

O

O

O

CH3

N

N

CH3

O

CH3

O

N

Common name AE F075736; metsulfuron-methyl

IUPAC name Methyl 2-[3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)ureidosulphonyl]benzoate

CAS name Methyl 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]-

benzoate

CAS registry number 74223-64-6

Molecular formula C14H15N5O6S

Table 2. Physicochemical Properties of the Technical Grade Metsulfuron-methyl

Parameter Value Reference

Melting point/range 158 °C

Water solubility (mg/L at 25°C)

109 at unbuffered, pH 4.1

270 at buffered pH 4.6

1750 at buffered pH 5.4

9500 at buffered pH 6.7

Solvent solubility (mg/L at 20°C)

0.79 in n-hexane 0.79

580 in xylene

2300 in ethanol

7300 in methanol

36000 in acetone

121000 in methylene chloride

Vapor pressure (@ 25°C) 2.5 X 10 -12 mm Hg

Octanol/water partition coefficient Log(KOW) 0.018
Page 13 of 21

Table 3A. Metsulfuron-methyl Toxicology Data Requirements

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 21/28-Day Dermal........................................................

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

870.3465 90-Day Inhalation.........................................................

yes

yes

yes

no

yes1

yes

yes

yes

---

no

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

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

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

yes

yes

yes

yes

yes

yes

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

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

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

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

870.4300 Chronic/Oncogenicity (mouse) ....................................

870.4500 Chronic/Oncogenicity (rat) ..........................................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

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

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

870.5375 Mutagenicity—Structural Chromosomal Aberrations..

870.5385 Mutagenicity—Structural Chromosomal Aberrations..

870.5395 Mutagenicity—Other Genotoxic Effects......................

870.5550 Mutagenicity—Other Genotoxic Effects......................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

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

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

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

870.6200 Chronic Neurotox. Screening Battery (rat) ..................

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

no

no

yes

yes

no

---

---

no

no

---

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

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

870.7800 Immunotoxity

yes

no

yes

yes

---

no

1 A 28-day inhalation study was previously required as a condition of registration for the use of 

metsulfuron-methyl on sorghum. At this time, the Agency has not received this study.
Page 14 of 21

Table 3B. Metsulfuron-methyl Acute Toxicity Profile

Guideline No. Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral – rat

94.9% a.i.

42545901 LD50 > 3000 

mg/kg (HDT)

III

870.1200 Acute dermal - rabbit

92.9% a.i.

00125828 LD50 > 2000 

mg/kg (ODT)

III

870.1300 Acute inhalation - rat

92.9% a.i.

00125830 LC50 > 5.3 

mg/L/4hr (dust 

inhalation)

IV

870.2400 Acute eye irritation –rabbit

95% a.i.

40357801 Moderate to 

severe irritation

I

870.2500 Acute dermal irritation – rabbit 

95.8% a.i.

40858802

42559604

Non-irritating IV

870.2600 Skin sensitization – guinea pig 

95.8% a.i.

40858803

42559600

Negative dermal 

sensitizer

N/A

Table 3C. Metsulfuron-methyl Subchronic, Chronic and Other Toxicity Profile

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

870.3100 13-Week feeding –

rat

125834 (1982)

Acceptable

NOAEL: 68/64 mg/kg/day (M/F)

LOAEL: 52 1/659 mg/kg/day (M/F) based on 

transient decreases in body weight gain

870.3200 21/28-Day dermal 

toxicity - rabbit

40357803 (1987) 

41247801 (1989)

Acceptable

Dermal NOAEL: 125 mg/kg/day

Dermal LOAEL: 500 mg/kg/day (skin lesions 

characterized by diffuse/multifocal dermatitis

Systemic NOAEL: 125 mg/kg/day

Systemic LOAEL: 500 mg/kg/day based on 

increased incidence of diarrhea.

870.3700 Prenatal 

developmental in 

the rat

125835 (1982) 

153318 (1985) 

Acceptable

Maternal NOAEL: 250 mg/kg/day

Maternal LOAEL: 1000 mg/kg/day based on 

salivation and decreased body weight gain -

compensatory increase after dosing stopped.

Developmental NOAEL: 1000 mg/kg/day 

(HDT) Developmental LOAEL: >1000 

mg/kg/day (HDT)

870.3700 Prenatal 

developmental in 

the rabbit

125836 (1982)

153319 (1985)

Acceptable

Maternal NOAEL: 25 mg/kg/day

Maternal LOAEL: 100 mg/kg/day based on 

increased mortality, decreased body weight 

gains, and clinical signs of anorexia, red/orange 

urine and/or exudate.

Developmental NOAEL: > 700 mg/kg/day 

(HDT) Developmental LOAEL: >700 

mg/kg/day (HDT)
Page 15 of 21

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

870.3800 Reproduction and 

fertility effects in 

the rat

151028 (1985)

Acceptable

Parental systemic NOAEL: 34/43 mg/kg/day 

(M/F) Parental systemic LOAEL: 342/475 

mg/kg/day (M/F) (decreased premating body 

weight gains by FO males and females).

Offspring/Reproductive NOAEL: > 342/475 

mg/kg/day (M/F) Offspring/Reproductive 

LOAEL: > 342/475 mg/kg/day (M/F)

870.4100 Chronic oral 

toxicity in the dog

141821 (1984)

Acceptable

NOAEL: >125 mg/kg/day (M/F) at the HDT 

LOAEL: not determined

870.4300 Carcinogenicity in 

the mouse by the 

oral route

151135 (1985)

Acceptable

NOAEL: 666/836 mg/kg/day (M/F) at the HDT 

LOAEL: not determined.

No evidence of carcinogenic potential of the 

test material.

870.4500 Combined 

Chronic/Carcinogenicity in the rat 

by the oral route

154477 (1985)

Acceptable

NOAEL: 25 mg/kg/day in M/F

LOAEL: 250 mg/kg/day in M/F (decreased 

body weight and body weight gain)

No evidence of carcinogenic potential of the 

test material.

870.5100 Salmonella 

typhimurium, 

Ames assay

125837 (1980)

Acceptable

Not mutagenic under the conditions of the 

study.

870.5375 In vitro mammalian 

chromosomal

aberrations - CHO 

cells (2 studies)

125838 (1982) 125839 

(1983)

Acceptable

Metsulfuron methyl is not a clastogen under the 

conditions of the study.

870.5385 In vivo mammalian 

chromosome 

aberrations - rat 

bone marrow

125840 (1983)

Acceptable

Metsulfuron methyl did not induce a significant 

increase in chromosome aberrations in bone 

marrow cells when compared to the vehicle 

control group.

870.5395 In vivo mammalian 

cytogenetics -

micronucleus assay 

in mice

41118002 (1989)

Acceptable

Metsulfuron methyl was negative at the limit 

dose for clastogenic activity in the 

micronucleus assay in bone marrow cells.

870.5550 UDS assay in 

primary rat 

hepatocytes/

mammalian cell 

culture

41773901 (1990)

42545801 (1990)

43035601 (1993)

Acceptable

Metsulfuron methyl was negative for UDS in 

mammalian hepatocytes in vivo.
Page 16 of 21

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

870.7485 Metabolism and 

pharmaco-kinetics 

in the rat

141828 (1984)

Acceptable

The primary route of excretion was via the 

urine which accounted for approx. 7 1-95% 

(78-96% if cage wash radioactivity is 

considered) among the various treatment 

groups. Fecal elimination was 4.8-13.3%. 

Tissue burdens were minimal (generally <0.1% 

to 1%) regardless of exposure protocol; the 

gastrointestinal tract, carcass, and skin had the 

highest concentrations of radioactivity. No 

evidence for sequestration of the test article or 

its biotransformation products.

Four metabolites and parent were recovered in 

both urine and feces in all treatment groups. 

Parent compound accounted for most of the 

urinary and fecal radioactivity (77-90% and 

1.8-6.2% of the administered dose, 

respectively). Metab. I was consistent with 

(methyl 2-[(amino)sulfonyl] benzoate); Metab. 

II - (2-[(amino)sulfonyl]-benzoic acid); and 

Metab. III was consistent with (methyl 2-

[[{(amino)carbonyl]aminoj sulfonyl] benzoate). 

Metab. I and II appeared to result from 

sequential hydrolysis reactions terminating in 

the formation of saccharin while Metab. III was 

formed by cleavage of the two ring structures. 

Total metabolites (in urine + feces of each 

group) accounted for approximately 5.4-8.2% 

of the administered dose. The metabolite 

profiles were qualitatively similar for urine and 

feces in that parent compound and the four 

metabolites (saccharin, Metabolites I, II, and 

III) were found in both matrices.
Page 17 of 21

Table 3D. Metsulfuron-methyl Summary of Toxicological Doses and Endpoints for 

Use in Dietary Human Health Risk Assessments.

Exposure 

Scenario

Point of 

Departure

Uncertainty/

FQPA SFs

Population Adjusted 

Dose for Risk 

Assessment

Study and Toxicological Effects

Acute Dietary 

All 

Populations

A single dose effect relevant to the general US population including infants and children 

was not identified in the toxicity studies conducted with metsulfuron-methyl.

Chronic 

Dietary (All 

Populations)

NOAEL = 25 

mg/kg/day

UFA = 10x

UFH =10x

FQPA SF= 

1x

cPAD = 0.25 

mg/kg/day

Rat, Oral 

Chronic/Carcinogenicity 

Toxicity Study

LOAEL = 250 mg/kg/day based 

on decreased body weight and 

body weight gain.

Incidental oral 

(short- & 

intermediateterm)

NOAEL = 34 

mg/kg/day 

(parental)

UFA = 10x

UFH =10x

FQPA SF= 

1x

Residential LOC for 

MOE = 100

Rat, 2 Generation Reproduction 

Study

LOAEL = 342 mg/kg/day based 

on decreased premating (FO) 

body weights.

Dermal 

exposure (all 

durations)

NOAEL = 125 

mg/kg/day

UFA = 10x

UFH =10x

FQPA SF= 

1x

Residential LOC for 

MOE = 100

Rabbit, 21 Day Dermal Exposure 

Study

LOAEL = 500 mg/kg/day based 

on increased incidences of 

diarrhea.

Inhalation 

exposure 

(short- & 

intermediate 

term)

NOAEL = 34 

mg/kg/day 

(parental)

Oral study

UFA = 10x

UFH =10x

FQPA SF= 

1x

IA = 100%

Residential LOC for 

MOE = 100

Rat, 2 Generation Reproduction 

Study

LOAEL = 342 mg/kg/day based 

on decreased premating (FO) 

body weights.

Inhalation 

exposure (long 

term)

NOAEL = 25 

mg/kg/day

Oral study

UFA = 10x

UFH =10x

FQPA SF= 

1x

IA = 100%

Residential LOC for 

MOE = 100

Rat, Oral 

Chronic/Carcinogenicity 

Toxicity Study

LOAEL = 250 mg/kg/day based 

on decreased body weight and 

body weight gain.

Cancer (oral, 

dermal, 

inhalation)

Metsulfuron methyl is classified as “not likely to be carcinogenic to humans.” This is based 

on the lack of evidence of carcinogenicity in mice and rats, no evidence of mutagenicity in 

acceptable studies, and the non-carcinogenic potential of structurally related compounds.

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).
Page 18 of 21

Table 3E. Metsulfuron-methyl Summary of Toxicological Doses and Endpoints for 

Metsulfuron methyl 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 

(all durations)

NOAEL = 125 

mg/kg/day

UFA = 10x

UFH =10x

Occupational LOC 

for MOE = 100

Rabbit, 21 Day Dermal 

Exposure Study

LOAEL = 500 mg/kg/day 

based on increased 

incidences of diarrhea.

Inhalation 

exposure (Short- & 

intermediate term)

NOAEL = 34 

mg/kg/day 

(parental)

Oral study

UFA = 10x

UFH =10x

IA = 100%

Occupational LOC 

for MOE = 100

Rat, 2 Generation 

Reproduction Study

LOAEL = 342 mg/kg/day 

based on decreased 

premating (FO) body 

weights.

Inhalation 

exposure (long 

term)

NOAEL = 25 

mg/kg/day

Oral study

UFA = 10x

UFH =10x

IA = 100%

Occupational LOC 

for MOE = 100

Rat, Oral 

Chronic/Carcinogenicity 

Toxicity Study

LOAEL = 250 mg/kg/day 

based on decreased body 

weight and body weight gain.

Cancer (oral, 

dermal, inhalation)

Metsulfuron methyl is classified as “not likely to be carcinogenic to humans.” This is 

based on the lack of evidence of carcinogenicity in mice and rats, no evidence of 

mutagenicity in acceptable studies, and the non-carcinogenic potential of structurally 

related compounds.

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 date (i.e., lack of a 

critical study). MOE = margin of exposure. LOC = level of concern. N/A = not applicable. IA = inhalation 

absorption factor
Page 19 of 21

Table 4. Metsulfuron-methyl International Residue Limits 

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico2 Codex3

40 CFR 180.428(a)1: 

Plants: combined residues of the 

herbicide metsulfuron methyl 

(methyl 2-[[[[(4-methoxy-6-methyl1,3,5- triazin- 2-

yl)amino]carbonyl]amino] sulfonyl] 

benzoate) and its metabolite methyl 

2-[[[[(4-methoxy-6-methyl-1-,3,5-

triazin-2-yl)amino]carbonyl]amino] 

sulfonyl]-4-hydroxybenzoate 

methyl 2-[[[[(4-methoxy-6-methyl1,3,5-triazin-2-yl)

amino]carbonyl]amino]sulfonyl]benzo

ate, including the

metabolite methyl 2-[[[[(4-methoxy-6-

methyl-1,3,5-

triazin-2-

yl)amino]carbonyl]amino]sulfonyl] 4-

hydroxybenzoate

None

Commodity1Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico2 Codex3

Barley, grain 0.1 0.1

Barley, hay 20.0

Barley, straw 0.3

Grass, forage 15.0

Grass, hay 15.0

Grass, straw 15.0

Sorghum, grain, forage 0.2

Sorghum, grain, grain 0.1

Sorghum, grain, stover 0.2

Sugarcane, cane 0.05

Wheat, forage 5.0

Wheat, grain 0.1 0.1

Wheat, hay 20.0

Wheat, straw 0.3

2 Canada Mexico2 Codex3

metsulfuron methyl (methyl2[[[[(4-methoxy- 6-methyl-1,3,5-

triazin-2- yl)amino]carbonyl]amino] 

sulfonyl] benzoate)

Same as above None

Commodity1 Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico2 Codex3

Cattle, fat 0.1 0.1

Cattle, kidney 0.5 0.5

Cattle, meat 0.1 0.1

Cattle, meat byproducts 0.1 0.1

Goat, fat 0.1 0.1

Goat, kidney 0.5 0.5

Goat, meat 0.1 0.1

Goat, meat byproducts 0.1 0.1

Hog, fat 0.1 0.1

Hog, kidney 0.5 0.5
Page 20 of 21

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico2 Codex3

Hog, meat 0.1 0.1

Hog, meat byproducts 0.1 0.1

Horse, fat 0.1

Horse, kidney 0.5

Horse, meat 0.1

Horse, meat byproducts 0.1

Milk 0.05 0.05

Sheep, fat 0.1

Sheep, kidney 0.5

Sheep, meat 0.1

Sheep, meat byproducts 0.1

1

Includes only commodities of interest for this action. Tolerance values should be the HED 

recommendations and not those proposed by the applicant.

2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.

3 * = absent at the limit of quantitation; Po = postharvest treatment, such as treatment of stored grains. PoP 

= processed postharvest treated commodity, such as processing of treated stored wheat. (fat) = to be 

measured on the fat portion of the sample. MRLs indicated as proposed have not been finalized by the 

CCPR and the CAC.
Page 21 of 21

Table 5: HED Memoranda Relevant to Registration Review

Author Barcode/TXR # Date Title

M. Collantes D282214 6/19/2002 Occupational and Residential Exposure and 

Risk for the Proposed Use of MetsulfuronMethyl on Sorghum. 

W. Cutchin, S. 

Williams-Foy, 

M. Collantes

D281907 6/26/2002 Human Health Risk Assessment for the 

Section 3 Registration of Metsulfuron 

Methyl on Grain Sorghum.