UNITED STATES ENVIRONM ENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

PC Code: 128973 

DP Barcode: 0394823 

MEMORANDUM March 1, 2012 

Subject: 

To: 

From: 

Registration Review: Preliminary Problem Fonnulation for Environmental Fate 

and Ecological Risk, Endangered Species, and Drinking Water Assessments for 

Primisulfuron methyl (Case # 7220) 

Kaitlin Keller, Team Lead (RM 53) 

Michael Goodis, Branch Chief, RMIB III 

Pesticide Re-Evaluation Division (7508P) 00 

Stephen Carey, Biologist /""~ ~~}II'l/ u. 

Andrew Shelby, Physical Scientist ~.......t..---\ /3 - I - Ie.. 

Environmental Risk Branch 6 'v- - 17 

Environmental Fate and Effects Division (7507P) 

Reviewed by: Ibrahim Abdel-Saheb, Ph.D., Environmental Scientist 

Brian Kiernan, Biologist 

Through: 

Environmental Risk Branch 6 

Environmental Fate and Effects Division (7507P) 

Mark Corbin, Branch Chief 

Environmental Risk Branch 6 

Environmental Fate and Effects Division (7507P) 

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem 

fonnulation (attached) for the environmental fate and ecological risk, endangered species, and 

drinking water assessments to be conducted as part of the Registration Review of the herbicide 

primisulfuron methyl (primisulfuron; PC Code 128973). Primisulfuron methyl is coformulated 

with other registered chemicals-in end use products (prosulfuron and dicamba). Functioning as 

the first stage of the risk assessment process for Registration Review, this problem formulation 

provides an overview of what is currently known about the environmental fate and ecological 

effects associated with primisulfuron methyl and its degradate CGA-171683. It also describes 

the preliminary ecological risk hypothesis and analysis plan for evaluating and characterizing 

risk to non-target species and the environment in support of registration review. 

I 

, 
2

Data Gaps

The available environmental fate and transport data are considered incomplete and inadequate 

for the purposes of risk assessment. The following data gaps exist:

• Submission of an acceptable aerobic aquatic metabolism (OPPTS guideline # 835.4300) 

study is necessary to understand the degradation of primisulfuron methyl in oxygen 

abundant aquatic environments. The guideline stipulates that at least two different 

sediment:water systems be submitted that are similar to the potential use sites in the 

United States. In the absence of this data, the model input for aerobic soil metabolism is 

doubled to conservatively estimate the model input for aerobic aquatic metabolism.

• Submission of an acceptable anaerobic aquatic metabolism (OPPTS guideline # 

835.4400) study is necessary to understand the degradation of primisulfuron methyl in 

oxygen-limiting environments. In the absence of this data, the model input for anaerobic 

soil metabolism is doubled to conservatively estimate the model input for anaerobic 

aquatic metabolism.

• There are currently terrestrial field dissipation studies (OPPTS guideline # 835.6100) 

under review by the Agency. Until the review is complete, EFED cannot be certain the 

data are sufficient for risk assessment. This study is necessary to understand the 

dissipation of primisulfuron methyl in field conditions.

• Supplemental to the terrestrial field dissipation studies are the independent laboratory 

method validation, and environmental chemistry methods used for the field study. 

The available effects dataset is considered incomplete for the purposes of risk assessment. The 

following data gaps exist:

• Primisulfuron methyl - OPPTS 850.2100; An avian acute oral study with a passerine is 

necessary for risk assessment. Until the data is available, EFED cannot be certain the 

data are sufficient for an ecological risk assessment on birds.

• Primisulfuron methyl - Non-guideline; Terrestrial Plant Reproduction Study will be 

necessary for risk assessment to fully evaluate the effects of primisulfuron methyl to 

plants at different stages.

• Degradate CGA171683 - OPPTS 850.2300; reproduction toxicity to upland game bird 

and waterfowls. Toxicity data on the environmental relevant degradate CGA171683 of 

primisulfuron methyl is necessary for risk assessment since CGA171683 is persistent in 

the environment with 75% of the degradate remaining after 12 months.

Additional detail on the current data gaps for environmental fate and effects for primisulfuron

methyl is provided in Section 8.0.
3 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

 

Problem Formulation for the Environmental Fate and 

Ecological Risk, Endangered Species, and Drinking 

Water Assessments in Support of the Registration 

Review of Primisulfuron methyl 

methyl 2-[[[[[4,6-bis(difluoromethoxy)-2-pyrimidinyl]amino]carbonyl]amino]sulfonyl]benzoate

CAS Registry Number: 86209-51-0 

PC Code: 128973 

Prepared by:

Stephen Carey, Biologist

Andrew Shelby, Physical Scientist

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch IV

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Brian Kiernan, Biologist

Ibrahim Abdel-Saheb, Ph.D., Environmental Scientist

Mark Corbin, Branch Chief

March 1, 2012 
4

1. Purpose

The purpose of this problem formulation is to provide an understanding of what is known about 

the environmental fate and ecological effects of the registered uses of primisulfuron methyl (PC 

Code 128973). Primisulfuron methyl belongs to the sulfonylurea class of herbicides and it is 

applied for selective control of annual and perennial broadleaf weeds and certain monocots in 

agricultural crop areas. Crop uses include field corn, popcorn, and Kentucky bluegrass grown for 

seed and sod. This herbicide is applied as post-emergent treatment and may be used on 

established plantings. Primisulfuron methyl is an acetolactate synthase (ALS) inhibitor. ALS is 

an important enzyme for the synthesis of branched chain amino acids. This metabolic pathway is 

present only in plants. Primisulfuron methyl is absorbed by the foliage and roots of plants. This 

document will provide a plan for analyzing data relevant to primisulfuron methyl and for 

conducting environmental fate and ecological risk, endangered species, and drinking water 

assessments for its registered uses. Additionally, this problem formulation is intended to identify 

data gaps, uncertainties, and potential assumptions used to address those uncertainties relative to 

characterizing the ecological risk associated with the registered uses of primisulfuron methyl. 

2. Problem Formulation

2.1. Nature of Regulatory Action

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), all pesticides distributed 

or sold in the United States generally must be registered by the Environmental Protection 

Agency (EPA). As part of determining whether a pesticide can be registered in the U.S., the 

Agency evaluates its safety to non-target species based on a wide range of environmental and 

health effects studies. In 1996, FIFRA was amended by the Food Quality Protection Act, and the 

Agency was mandated to implement a new program for the periodic review of pesticides, i.e., 

Registration Review (http://www.epa.gov/oppsrrd1/registration_review/). The Registration 

Review program is intended to ensure that, as the ability to assess risk evolves and as policies 

and practices change, all registered pesticides continue to meet the statutory standard of no 

unreasonable adverse effects to human health and the environment. Changes in science, public 

policy, and pesticide use practices occur over time. Through the Registration Review program, 

the Agency periodically reevaluates pesticides to make sure that as change occurs, products in 

the marketplace can be used safely. 

As part of the implementation of the Registration Review program pursuant to Section 3(g) of 

the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the Agency is beginning its 

evaluation of primisulfuron methyl to determine whether it continues to meet the FIFRA 

standard for registration. This problem formulation for the environmental fate, ecological risk, 

endangered species, and drinking water assessment chapter in support of the Registration Review 

will be posted in the initial docket, which will open the public phase of the review process.
5

2.2. Previous Risk Assessments

In 1988, the Agency granted an Experimental Use Permit for primisulfuron methyl on corn. In 

1990, the Agency produced a hazard assessment for the full registration of primisulfuron methyl

for use as selective weed control in corn. At that time, there were many data gaps for 

primisulfuron methyl, including batch equilibrium, terrestrial field dissipation, avian 

reproduction, freshwater fish, freshwater invertebrate, estuarine invertebrate, fish early life stage, 

fish life cycle and fish bioaccumulation studies. Due to unknown mobility, leaching to 

groundwater was also a potential concern. 

In 1991, the Agency reviewed a request to allow aerial application of primisulfuron methyl on 

corn and concluded that the potential for adverse effects to nontarget terrestrial and aquatic 

plants would be dramatically increased. None of the previously identified data gaps were 

addressed for this action.

In 1994, the Agency qualitatively reviewed all sulfonylurea herbicides and recommended that all 

aerial applications be rescinded and all ground applications be reconsidered due to a potential for 

serious adverse effects based on evidence from incidents and field studies.

In 1998, EPA received two Section 18 requests (emergency use exemptions;1998) from 

Washington and Idaho were for weed control in Kentucky bluegrass grown for seed to control 

quackgrass, cheatgrass, downy brome, windgrass and wild oat. Approximately 71,000 acres were 

treated with primisulfuron methyl at 0.036 lb a.i./A/yr or a total of 2,500 lb a.i.

EFED conducted an ecological fate and effects hazard assessment dated October 4, 1991 for 

primisulfuron methyl; however, no ecological risk assessment was conducted for primisulfuron 

methyl.

3. Stressor Source and Distribution

3.1. Mechanism of Action

Primisulfuron methyl’s mode of action is the inhibition of amino acid synthesis in plants through 

inhibition of acetolactate synthase (ALS). ALS is the first common enzyme in the biosynthesis 

of branched-chain amino acids (valine, leucine, and isoleucine). ALS inhibition in plants 

adversely affects plant growth and reproduction. Although acetolactate is present in mammals, 

the biosynthesis of branch chain amino acids occurs only in plants. Chlorsulfuron (PC Code 

118601), the most studied pesticidal sulfonyl urea (SU), does not affect acetolactate forming 

enzymes in mammalian cells (Nakata, 1991). SUs in general are less toxic to animals than 

plants.
6

3.2. Overview of Pesticide Use and Usage

Primisulfuron methyl belongs to the sulfonylurea class of herbicides and it is applied for 

selective control of annual and perennial broadleaf weeds and certain monocots in field corn, 

popcorn, and Kentucky bluegrass grown for seed and sod. This herbicide is applied as a postemergence treatment and may be used on established planting. According to the Biological and 

Economic Analysis Division’s (BEAD) Screening Level Usage Analysis (SLUA; USEPA 2011), 

roughly 30,000 lbs of primisulfuron methyl is applied annually to corn in the U.S. Usage data 

for Kentucky bluegrass is unavailable.

Primisulfuron methyl is also co-formulated with other active ingredients, prosulfuron and 

dicamba sodium salt, in separate end use products. Primisulfuron methyl is formulated as a 

water dispersible granule intended for tank mixing with water. The application rate varies with 

use site, stage of weed growth, and coformulants; maximum single application rate is 0.036 lbs 

a.i./A for all use patterns and aerial applications may be performed. For further information, see 

‘BEAD Chemical Profile for Registration Review: Primisulfuron methyl (128973)’ (EPA 2011).

Based on private market survey data for the most recent years of 2008-2010, use on corn 

averaged approximately 8,000 lbs for 350,000 treated acres (EPA 2011). Over the last decade 

usage in corn has significantly declined. The reason for the decline is not clear, but it could be 

due to the wider use of Roundup ready corn in U.S. field corn production. For 2008-2010, the 

states with the most use in term of pounds a.i. applied were Illinois (30%), Nebraska (12%), 

Pennsylvania (11%), and Indiana (11%).

3.3. Environmental Fate and Transport

Primisulfuron methyl is moderately persistent in soil with half lives ranging from 30 to 89 days 

in aerobic and anaerobic conditions. It is mildly water soluble with a relatively low octanol/water 

partition, and it is relatively stable to photolysis. Primisulfuron methyl has been described as 

mobile in sandy soils with low organic content and is not likely to bioaccumulate in aquatic 

organisms. Primisulfuron methyl is stable to hydrolysis at environmentally relevant pHs. 

Therefore, primisulfuron methyl may be expected to persist in aquatic environments considering 

aerobic and anaerobic aquatic metabolism studies are unfulfilled data requirements.

Table 1 presents the general physical and chemical, as well as the available environmental fate 

properties of primisulfuron methyl.
7

Table 1. General Chemical Properties and Environmental Fate Properties of Primisulfuron 

Methyl.

Parameter Value Reference (MRID #) 

/Comment

Physical/Chemical Parameters

Molecular mass 468.34 g/mol 40331203

Vapor pressure (25°C) 3.8 x 10-8 torr 40331203

Henry’s Law Constant Not Available

Water solubility (20°C) 70 mg/L (in water) 40331203

Octanol-water partition coefficient (KOW) 1.58 40331203

Dissociation Constant (pKa) 5.1 40331203

Mobility

Soil Partitioning Coefficient (Koc, 1/n) 74.5, 57.4, and 66.3 mL/goc

0.9135, 0.9845, and 0.9595 (1/n values)

40331264

40856513

41869302

41869304

Persistence in Water

Hydrolysis half-life (25°C) pH 7 & 9: Stable

pH 5: >30 days

40331261

Aqueous photolysis half-life (25°C) Stable 40856508

40856509

41418611

Aerobic aquatic metabolism half-life No available data

Anaerobic aquatic metabolism half-life No available data

Persistence in Soil

Soil photolysis Stable 41418612

Aerobic soil metabolism half-life (25°C) 63 days

30 days

40331263

41418613

Anaerobic soil metabolism 41 days

89 days

41418614

40331263

Field Dissipation

Terrestrial field dissipation half-life (DT50) 5-9 days All studies are 

supplemental

40512015

40512016

40512017

40512018

40512019

Aquatic Bioconcentration

Bioconcentration Factor (BCF) in fish Low Kow indicates low potential to 

bioaccumulate.

Primisulfuron methyl is not volatile, having a vapor pressure of 3.8 x 10-8 torr. It is stable to 

hydrolysis at pH 7 and 9, but at pH 5, some amount of degradation was observed with a half-life 

greater than 30 days (MRID 40331261). It is also stable to photolysis. The Kow is low and does 

not indicate a potential to bioaccumulate. 

The mobility of primisulfuron methyl appears to vary with soil types and correlate with CEC and

clay content. Primisulfuron methyl will have a tendency to leach in sandy, inorganic soils. 
8

The degradation of primisulfuron methyl in aerobic soil ranged from 30 to 63 days, and is 

considered moderately persistent in soil (MRIDs 40331263 and MRID 41418613). Data for one 

of the major metabolites, (CGA-171683), show that the metabolite is persistent and will remain 

in the soil after the parent has degraded (present at 75% of applied concentration at 12 months, 

MRID 41418613). CGA-171683 was also the primary degradation product of pyrimidinelabeled primisulfuron methyl in anaerobic soil reaching 75% of applied radioactivity at 3 months 

(MRID 41418614). This degradation product consists of the pyrimidine group from parent 

primisulfuron methyl cleaved at the first amine group in the sulfonylurea group. Phenyl-labeled 

primisulfuron methyl is stable to hydrolysis in neutral and alkaline conditions but degrades at pH 

5. The primary degradation product detected is CGA-120844, a benzoate group cleavage 

product. Because these metabolism studies were conducted with pyrimidine-labeled 

primisulfuron methyl and the hydrolysis study was conducted with phenyl-labeled primisulfuron 

methyl, it appears that different major degradates are forming. However, CGA-171683 and 

CGA-120844 appear to be products of the same cleavage process. 

There is no available data for aerobic or anaerobic aquatic metabolism, therefore for the purposes 

of risk assessment the compound is assumed to have half lives double that of aerobic, 126 days,

and anaerobic soil, 178 days, respectively (USEPA, 2009).

Supplemental terrestrial field dissipation data reported results with dissipation half-lives ranging 

from 5 to 9 days (MRID 40512015, 40512016, 40512017, 40512018, 40512019). It is important 

to note that the pattern of formation and decline of the degradates was not addressed. The 

compound may leach in low organic matter soils (which is consistent with other sulfonylurea 

herbicides), however adequate field dissipation data have not yet been reviewed to characterize 

the extent of potential ground water contamination.

 3.3.5. Bioaccumulation

The low Kow of 1.58 indicates a low potential for bioaccumulation. Therefore, bioaccumulation 

studies have not been required.

4. Receptors

The receptor is the biological entity that is exposed to the stressor (EPA, 1998.) Given its 

widespread use, all types of biological receptors (birds, mammals, terrestrial plants, freshwater 

fish, etc.) are expected to be potentially exposed to primisulfuron methyl.

Consistent with the process described in the Overview Document (EPA, 2004), this risk 

assessment uses a surrogate species approach in its evaluation of primisulfuron methyl. 

Toxicological data generated from surrogate test species, which are intended to be representative 

of broad taxonomic groups, are used to extrapolate to potential effects on a variety of species 

(receptors) included under these taxonomic groupings. 

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the 

available open literature are used to evaluate the potential direct effects of the herbicide to the 
9

aquatic and terrestrial receptors identified in this section. This includes toxicity data on the 

technical grade active ingredient, degradates, and when available, formulated products (e.g. “SixPack” studies of mammalian toxicity). The open literature studies are identified through EPA’s 

ECOTOX database (http://cfpub.epa.gov/ecotox/), which employs a literature search engine for 

locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. The evaluation of 

both sources of data can also provide insight into the direct and indirect effects of primisulfuron 

methyl on biotic communities from loss of species that are sensitive to the chemical and from 

changes in structure and functional characteristics of the affected communities. 

Table 3 provides a summary of the taxonomic groups and the surrogate species tested to help 

understand potential acute ecological effects of pesticides to these non-target taxonomic groups. 

In addition, the table provides a preliminary overview of the potential acute toxicity of 

primisulfuron methyl by providing the acute toxicity classifications. 

Table 3. Test Species Evaluated for Assessing Potential Ecological Effects of 

Primisulfuron methyl and the Associated Acute Toxicity Classification 

Taxonomic Group Example(s) of Surrogate Species Acute Toxicity Classification

Birds1

Mallard duck (Anas platyrhynchos)

Bobwhite quail (Colinus virginianus)

Passerine bird 

Practically nontoxic a

Mammals Laboratory rat (Rattus norvegicus) Practically nontoxic

Insects Honey bee (Apis mellifera L.) Practically nontoxic

Freshwater fish2

Bluegill sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)

Fathead minnow (Pimephales promelas)

Practically nontoxic

Freshwater invertebrates Water flea (Daphnia magna) Practically nontoxic

Estuarine/marine fish Sheepshead minnow (Cyprinodon 

variegatus) Practically nontoxic

Estuarine/marine 

invertebrates

Mysid shrimp (Americamysis bahia)

Quahog clam (Mercenaria 

mercenaria)

Slightly toxic

Terrestrial plants

Carrot (Daucus carota subsp. Sativus)

Tomato (Lycopersicon esculentum var. 

esculentum)

Onion (Allium cepa)

No toxicity classification 

available for plants

Aquatic plants and algae Duckweed (Lemna gibba)

Cyanobacteria (Anaebaena flos-aquae) 1 Birds represent surrogates for terrestrial-phase amphibians and reptiles. 2 Freshwater fish may be surrogates for aquatic-phase amphibians. a Data are incomplete pending passerine submission

4.1. Incident Database Review

A review of the Ecological Incident Information System (EIIS) database for incidents involving 

primisulfuron methyl was conducted on December 21, 2011. Sixty-seven plant incidents are 

reported in the database (Appendix C). These plant incidents occurred on agricultural areas, 

corn, with possible misuses on soybean and sugar beet sites since primisulfuron methyl was not 
10

registered for those uses, and ranged in certainty from ‘possible’ to ‘probable’, with one 

‘unlikely’. The magnitude of response varied from 1 to 4000 acres. 

Similarly, a search of the Avian Incident Monitoring System (AIMS; 

http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims/index.cfm), a database 

administered by the American Bird Conservancy which contains publicly available data on 

reported avian incidents involving pesticides. No avian incidents have been recorded for 

primisulfuron methyl in this database. 

Pesticide registrants report certain types of incidents to the Agency as aggregate counts of 

incidents occurring per product per quarter. Sixty-nine aggregated plant incidents have been 

reported to the Agency associated with primisulfuron methyl since 1998. Similar to the EIIS 

database, they resulted from registered uses (16 reports) and misuses (53 reports). 

4.2. Ecosystems Potentially at Risk

The ecosystems at risk are often extensive in scope; therefore, it may not be possible to identify 

specific ecosystems during the development of a nation-wide ecological risk assessment. 

However, in general terms, terrestrial ecosystems potentially at risk could include the treated 

field and immediately adjacent areas that may receive drift or runoff. Areas adjacent to the 

treated field could include cultivated fields, fencerows and hedgerows, meadows, fallow fields or 

grasslands, woodlands, riparian habitats and other uncultivated areas. 

Aquatic ecosystems potentially at risk include water bodies adjacent to, or downstream from, the 

treated field and could include impounded bodies such as ponds, lakes and reservoirs, or flowing 

waterways such as streams or rivers. For uses in coastal areas, aquatic habitat also includes 

marine ecosystems, including estuaries. 

5. Assessment Endpoints

Assessment endpoints represent the actual environmental value that is to be protected, defined by 

an ecological entity (species, community, or other entity) and its attribute or characteristics 

(EPA, 1998). For primisulfuron methyl, the ecological entities include the following: birds, 

mammals, reptiles, amphibians, freshwater fish and invertebrates, estuarine/marine fish and 

invertebrates, terrestrial plants, insects, and aquatic plants and algae. The attributes for each of 

these entities may include growth, reproduction, and survival.
11

6. Conceptual Model

For a pesticide to pose an ecological risk, it must reach ecological receptors in biologically 

significant concentrations. An exposure pathway is the means by which a pesticide moves in the 

environment from a source to an ecological receptor. For an ecological pathway to be complete, 

it must have a source, a release mechanism, an environmental transport medium, a point of 

exposure for ecological receptors, and a feasible route of exposure.

The conceptual model for primisulfuron methyl provides a written description (risk hypothesis) 

and visual representation (conceptual diagram) of the predicted relationships between 

primisulfuron methyl, potential routes of exposure, and the predicted effects for the assessment 

endpoint (USEPA 1998b).

Based on the available data, primisulfuron methyl is water soluble, stable in neutral to alkaline 

water, and also stable to photolytic degradation. Primisulfuron methyl is moderately persistent 

in soil under aerobic and anaerobic conditions though there is uncertainty of persistence in 

aquatic environments due to a lack of data. It is mobile in soil, is not volatile, and, given its 

relatively low Kow, is not likely to accumulate in aquatic food webs. With these properties, it 

appears that primisulfuron methyl is mobile and has a potential to leach into ground water or 

move offsite into surface water. 

Additionally, in general, SU herbicides are known to be very toxic to sensitive non-target plants. 

When used in accordance with the label, primisulfuron methyl may move off the site of 

application by spray drift and/or runoff. This may result in potential risk to the reproduction in 

terrestrial non-target plants inhabiting adjacent or nearby acreage below the threshold known to 

cause effects in guideline studies. 

6.1. Risk Hypothesis

For primisulfuron methyl, the following ecological risk hypothesis is being employed for this 

baseline risk assessment:

Primisulfuron methyl, when used in accordance with the label, may result in potential adverse 

effects upon the survival, growth, and reproduction of non-target terrestrial and aquatic 

organisms. Given the degree of persistence of primisulfuron methyl and its degree of mobility, 

there is a likelihood of exposure to terrestrial and/or aquatic organisms. 

6.2. Conceptual Diagram

The conceptual model used to depict the potential ecological risk associated with the use of 

primisulfuron methyl (the stressor) assumes that as a pesticide, primisulfuron methyl can 

adversely affect terrestrial and aquatic organisms (the receptors) if environmental concentrations 

exceed toxic thresholds as a result of application according to the label directions (Figures 1, 2

and 3). Ecological receptors that may potentially be exposed to primisulfuron methyl include 

terrestrial and semi-aquatic wildlife (e.g., mammals, birds, terrestrial-phase amphibians and 
12

reptiles), terrestrial and semi-aquatic plants, and terrestrial invertebrates (e.g., honey bees). 

Additionally, given the mobility of primisulfuron methyl, aquatic organisms (i.e., freshwater and 

estuarine/marine fish and invertebrates, aquatic-phase amphibians, and aquatic plants) are 

potential receptors in adjacent water bodies through off-site transport of primisulfuron methyl 

from the application site through runoff, erosion, and spray drift.

Figure 1. Conceptual model for primisulfuron methyl exposure to aquatic organisms and 

plants. Dashed lines indicate route of exposure considered of lower importance for primisulfuron methyl.

Stressor

Source

Receptors

Attribute

Change

Primisulfuron methyl

Spray drift

Aquatic Animals

Eggs 

Larvae 

Juveniles / Adults

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae

Reduction in prey

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Surface water

(including direct application)

Runoff

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Uptake/gills 

or integument

Ingestion Ingestion

Atmospheric 

transport

Wet/dry deposition

Soil Ground water

Uptake/gills 

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake/cell, 

roots, leaves Riparian plant

terrestrial 

exposure 

pathways see 

Figure 2
13

Figure 2. Conceptual model for primisulfuron methyl exposure to terrestrial animals and 

plants. Dashed lines indicate route of exposure considered of lower importance for primisulfuron methyl.

Stressor

Source

Receptors

Attribute

Change

Primisulfuron methyl

Direct

application Spray drift

Birds / Terrestrialphase amphibians / 

reptiles / mammals/ 

Insects

Terrestrial 

inverts

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in prey

Habitat integrity

Reduction in primary 

productivity

Reduced cover

Community change

Terrestrial/riparian plants

grasses/forbs, fruit, seeds 

(trees, shrubs)

Runoff

Mammals

Exposure

Media

Soil

Ingestion

Ingestion

Ingestion

Ingestion

Dermal uptake/Ingestion

Atmospheric 

transport

Root uptake

Wet/dry 

Birds / 

Amphibians

Ingestion

Groundwater

Irrigation 

Water
14

Stressor

Source

Attribute

Change

Primisulfuron-methyl applied to use site

Direct

application Spray drift

Terrestrial 

vertebrates

Terrestrial 

invertebrates

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in prey and food

Modification of PCEs 

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related

to habitat

Runoff

Exposure Media Dew (formed on 

terrestrial plants)

Atmospheric 

transport

Receptors

Puddles (formed on 

treated fields)

Inhalation Ingestion

Air

Figure 3. Conceptual diagram for drinking water and inhalation exposure pathways and effects of 

primisulfuron methyl uses on non-target terrestrial animals. Dashed lines indicate route of exposure 

considered of lower importance for primisulfuron methyl.

7. Analysis Plan

In order to address the risk hypothesis, the potential for adverse effects on the environment will 

be estimated. The use, environmental fate, and ecological effects of primisulfuron methyl will 

be characterized and integrated to assess the risks. This will be accomplished using a risk 

quotient (ratio of exposure concentration to effects concentration) approach. Although risk is 
15

often defined as the likelihood and magnitude of adverse ecological effects, the risk quotientbased approach does not provide a quantitative estimate of likelihood and/or magnitude of an 

adverse effect. However, as outlined in the Overview Document (USEPA 2004), the likelihood 

of effects to individual organisms from particular uses of primisulfuron methyl may be estimated 

using the probit dose-response slope and either the level of concern (discussed below) or the 

actual calculated risk quotient value. 

This analysis plan will be revisited and may be revised depending upon the information 

submitted by the public in response to the opening of the Registration Review docket for 

primisulfuron methyl.

7.1. Stressors of Concern

The stressor of concern in the assessment will be primisulfuron methyl and degradate CGA171683. The Agency does not routinely include an evaluation of mixtures of active ingredients, 

either those mixtures of multiple active ingredients in product formulations or those in the 

applicator’s tank. In the case of the product formulations of active ingredients (that is, a 

registered product containing more than one active ingredient), each active ingredient is subject 

to an individual risk assessment for regulatory decision regarding the active ingredient on a 

particular use site. If effects data are available for a formulated product containing more than 

one active ingredient, the data may be used qualitatively or quantitatively in accordance with the 

Agency’s Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs document and the Services’ Evaluation Memorandum (USEPA, 2004; Williams and 

Hogarth, 2004).

7.2. Measures of Exposure

Aquatic Exposure

In order to estimate risks of primisulfuron methyl exposures in aquatic environments, exposure 

modeling will be based on maximum application rates and methods as on the labels. Measures of 

exposure are based on aquatic models that predict estimated environmental concentrations 

(EECs) of primisulfuron methyl. The models used to predict aquatic EECs are the Pesticide Root 

Zone Model coupled with the Exposure Analysis Modeling System (PRZM/EXAMS). These 

models are parameterized using relevant reviewed environmental fate data from registrant 

submissions and the literature. Model input values will be consistent with the most recent 

version of the input parameter guidance (Version 2.1; USEPA 2009).

PRZM and EXAMS are simulation models coupled with the linkage program shell: PE5 (PRZM 

EXAMS Model Shell), which incorporates the standard scenarios developed by EFED. The 

models generate daily exposures and calculated 1-in-10 year EECs of primisulfuron methyl and 

possibly (depending on the outcome of environmental fate studies) toxicologically significant 

degradation products. PRZM simulates pesticide fate and transport as a result of leaching, direct 

spray drift, runoff and erosion from an agricultural field, and EXAMS estimates environmental 

fate and transport of pesticides in a surface water body for a 30-year period. The combined 
16

model is designed to estimate pesticide concentrations found in water (standard pond) at the edge 

of the treated field. As such, it provides high-end values of the pesticide concentrations that 

might be found in ecologically sensitive environments following pesticide application. The 

location of the field is specific to the crop being simulated using site-specific information on the 

soils, weather, cropping, and management factors associated with the scenario. The 

crop/location scenario is intended to represent a high-end exposure site on which the crop is 

normally grown. Based on historical rainfall patterns, the receiving water body receives multiple 

runoff events during the years simulated. Weather and agricultural practices are simulated for 30 

years so that the 10-year exceedance probability at the site can be estimated. The simulation is 

generated using 30 years of meteorological data, encompassing the years from 1961 to 1990. 

Additional information on these models can be found at: 

http://www.epa.gov/oppefed1/models/water/index.htm. 

The standard scenarios used for ecological pesticide assessments assume application to a 10-

hectare agricultural field that drains into an adjacent 1-hectare water body that is 2 meters deep 

(20,000 m3 volume) with no outlet. PRZM/EXAMS is used to estimate screening-level exposure 

of aquatic organisms to primisulfuron methyl. The measure of exposure for aquatic species is 

the 1-in-10 year return peak or rolling mean concentration. The 1-in-10 year peak is used for 

estimating acute exposures of direct effects to aquatic organisms. The 1-in-10-year 60-day mean 

is used for assessing chronic exposure to fish and aquatic-phase amphibians. The 1-in-10-year 

21-day mean is used for assessing chronic exposure to aquatic invertebrates.

Due to the persistence and mobility of primisulfuron methyl and its degradates, an irrigation 

assessment will be performed to determine environmental exposure from primisulfuron methylcontaminated groundwater used for irrigation. Irrigation will be assessed with the groundwater 

model approved for use at the time of the risk assessment.

Terrestrial Exposure

In order to estimate risks of primisulfuron methyl exposures in terrestrial environments, exposure 

modeling will be based on maximum application rates and methods as on the labels. Measures of 

exposure are based on terrestrial models that predict estimated environmental concentrations 

(EECs) of primisulfuron methyl. The model used to predict terrestrial EECs on food items is the 

Terrestrial Residue Exposure model (T-REX). The model used to derive EECs relevant to 

terrestrial plants is TerrPlant. These models are parameterized using relevant reviewed data from 

registrant submissions and the literature. Model input values will be consistent with the most 

recent version of the input parameter guidance (Version 2.1; USEPA 2009).

Exposure estimates for terrestrial organisms assumed to be in the target area or in an area 

exposed to off-site deposition are derived using the T-REX model. This model incorporates the 

Kenaga nomograph, as modified by Fletcher et al. (1994), which is based on a large set of field 

residue data. The upper limit values from the nomograph represent the upper bound of residue 

values from actual field measurements (Hoerger and Kenaga 1972). The Fletcher et al. (1994) 

modifications to the Kenaga nomograph are based on measured field residues from 249 

published research papers, including information on 118 species of plants, 121 pesticides, and 17 
17

chemical classes. Based on these data, T-REX assumes a 35-day foliar dissipation half-life in 

the absence of other data.

In order to determine if more data are necessary, the Screening Tool for Inhalation Risk (STIR)

was used to calculate an upper bound estimate of exposure using primisulfuron methyl’s vapor 

pressure and molecular weight for vapor phase exposure as well as the maximum application rate 

and method of application for spray drift. STIR incorporates results from several toxicity studies 

including acute oral and inhalation rat toxicity endpoints obtained from the “six-pack” of core 

studies, which are a series of six guideline studies that are submitted to the Registration Division 

of the Office of Pesticide Programs for technical and formulated products of a pesticide as well 

as the most sensitive acute oral avian toxicity endpoint. Based on the results of the STIR model, 

inhalation exposure alone was determined not to be a potential pathway of concern for avian or 

mammalian species on an acute exposure basis. 

Inhalation exposure via spray drift and/or vapor-phase of the pesticide alone does not appear to

be of concern. The analysis of the inhalation route in STIR does not consider that aggregation 

with other exposure pathways such as dietary, dermal, or drinking water may contribute to a total 

exposure that has a potential for effects to non-target animals. However, the Agency does 

consider the relative importance of other routes of exposure in situations where data indicate that 

pesticide exposures through other routes may be potentially significant contributors to wildlife 

risk (USEPA, 2004). The risk assessment will discuss the impact of consideration of other 

routes of exposure that have been identified as potentially important and the degree of certainty 

associated with screening-level risk assessment conclusions. Detailed information about STIR, 

as well as the tool, can be found on the EPA’s website 

at:http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial.

The Screening Imbibition Program (SIP) was used to calculate an upper bound estimate of 

exposure using primisulfuron methyl’s solubility, the most sensitive acute and chronic avian and 

mammalian toxicity endpoints. Drinking water exposure alone was determined not to be a 

potential pathway of concern for both avian (and surrogates) and mammalian species on an acute 

and chronic exposure basis. This route of exposure will be considered further in the risk 

assessment. Detailed information about the SIP v.1.0, as well as the tool, can be found on the 

EPA’s website at http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial.

EECs for terrestrial plants are derived using TerrPlant. This model uses estimates of pesticides in 

runoff and in spray drift to calculate EECs. EECs are based upon solubility, application rate and 

minimum incorporation depth. 

The AgDRIFT or AgDISP spray drift model may be used to assess exposures of organisms to 

primisulfuron methyl deposited on terrestrial habitats by spray drift.
18

7.3. Measures of Effect

Ecological effects data are used as measures of direct and indirect effects to biological receptors. 

Effects data are obtained from registrant-submitted studies or from literature studies identified by 

the ECOTOX database. When guideline or open literature studies are not available, a 

quantitative structure-activity relationship (QSAR) model may be used as a surrogate to estimate 

the effects. 

The acute measures of effect used for animals in this assessment are the LD50, LC50 and EC50. 

LD stands for "Lethal Dose", and LD50 is the amount of a material, given all at once, that is 

estimated to cause the death of 50% of the test organisms. LC stands for “Lethal Concentration” 

and LC50 is the concentration of a chemical that is estimated to kill 50% of the test organisms. 

EC stands for “Effective Concentration” and the EC50 is the concentration of a chemical that is 

estimated to produce a specific effect in 50% of the test organisms. Endpoints for chronic 

measures of exposure for listed and non-listed animals are the NOAEL/NOAEC and NOEC. 

NOAEL stands for “No Observed-Adverse-Effect-Level” and refers to the highest tested dose of 

a substance that has been reported to have no harmful (adverse) effects on test organisms. The 

NOAEC (i.e., “No-Observed-Adverse-Effect-Concentration”) is the highest test concentration at 

which none of the observed effects were statistically different from the control. For plants, only 

acute exposures are assessed (i.e., EC25 for terrestrial plants and EC50 for aquatic plants); for 

listed plants either the NOAEC or EC05 is used. 

Where available, sublethal effects observed in both registrant-submitted and open literature 

studies will be evaluated qualitatively. Such effects may include behavioral changes (e.g., 

lethargy and changes in coloration). Quantitative assessments of risks, though, are limited to 

those endpoints that can be directly linked to the Agency’s assessment endpoints of impaired 

survival, growth and reproduction.

In the absence of taxon-specific data, the assessment of risk for direct effects to non-target 

organisms makes the assumption that toxicity of primisulfuron methyl to birds is similar to 

terrestrial-phase amphibians and reptiles. The same assumption is made for fish and aquaticphase amphibians. 

Table 4 lists the measures of environmental exposure and ecological effects used to assess the 

potential risks of primisulfuron methyl to non-target animals and plants. The methods used to 

assess the risk are consistent with those outlined in the Overview Document (USEPA, 2004). 

Table 4 - Measures of Exposure and Effect Used in Assessing Potential Risks Associated 

with the Proposed Use of Primisulfuron methyl on Corn and KY Bluegrass Grown for Sod

Assessment Endpoint Surrogate Species and Measures of 

Ecological Effect1 Measures of Exposure

Birds, terrestrialphase amphibians 

and reptiles2

Survival

Lowest acute oral LD50

(Northern bobwhite quail and mallard duck) 

and subacute dietary LC50 (Northern 

bobwhite quail and mallard duck)

Upper-bound residues on 

food items (foliar)

Reproduction 

and Growth Lowest reproduction NOAEC (duck)
19

Table 4 - Measures of Exposure and Effect Used in Assessing Potential Risks Associated 

with the Proposed Use of Primisulfuron methyl on Corn and KY Bluegrass Grown for Sod

Assessment Endpoint Surrogate Species and Measures of 

Ecological Effect1 Measures of Exposure

Mammals

Survival Laboratory rat acute oral LD50 

Reproduction 

and Growth Laboratory rat reproduction NOAEC

Freshwater fish and 

aquatic-phase 

amphibians3

Survival Lowest acute LC50 (rainbow trout) Peak EEC

Reproduction 

and Growth

Lowest reproduction NOAEC (fathead 

minnow)

60-day average EEC

Freshwater 

invertebrates 

Survival Water flea acute EC50 Peak EEC

Reproduction 

and Growth Water flea reproduction NOAEC 21-day average EEC

Estuarine/marine 

fish

Survival Sheepshead minnow acute LC50 Peak EEC

Reproduction 

and Growth Sheepshead minnow reproduction NOAEC 60-day average EEC

Estuarine/marine 

invertebrates

Survival Lowest acute EC50/LC50 (mysid shrimp) Peak EEC

Reproduction 

and Growth Mysid shrimp reproduction NOAEC 21-day average EEC

Terrestrial plants4 Survival and 

growth

Lowest EC25 for non-listed plants and 

corresponding NOAEC (or EC05) for listed 

plants from seedling emergence (monocotonion; dicot- tomato) and vegetative vigor 

(monocot- onion; dicot- carrot) studies

Estimates of drift and runoff 

to non-target areas

Insects Survival (not 

quantitatively 

assessed)

Honeybee acute contact LD50 Maximum application rate

Aquatic plants Survival and 

growth

Lowest EC50 for non-listed plants and 

corresponding NOAEC (or EC05) for 

listed plants for algal (cyanobacteria) 

and vascular plant (duckweed)

Peak EEC

1 The most sensitive species tested within taxonomic groups is used for baseline risk assessments.

2 Birds represent surrogates for amphibians (terrestrial-phase) and reptiles. 3 Freshwater fish represent surrogates for amphibians (aquatic-phase). 4 Four species of two families of monocots - one is corn, six species of at least four dicot families, of which one is 

soybeans. 

5 LD50 = Lethal dose to 50% of the test population; NOAEC = No observed adverse effect concentration; LOAEC = 

Lowest observed adverse effect concentration; LC50 = Lethal concentration to 50% of the test population; EC50/EC25

= Effect concentration to 50%/25% of the test population.

7.4. Integration of Exposure and Effects

The exposure and toxicity effects data are integrated in order to evaluate the risks of adverse 

ecological effects on non-target species. For the assessment of primisulfuron methyl risks, the 

risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are 

divided by acute and chronic toxicity values. The resulting RQs are then compared to the 
20

Agency’s Levels of Concern (LOCs) (USEPA 2004) (Table 5). These criteria are used to 

indicate when primisulfuron methyl use, as directed on the labels, has the potential to cause 

adverse direct or indirect effects to non-target organisms. In addition, incident data from the 

EIIS will be considered as part of the risk characterization. 

Table 5 - Agency Risk Quotient (RQ) Metrics and Levels of Concern (LOC) Per Risk Class

RISK CLASS RISK DESCRIPTION RQ LOC

Aquatic Animals (fish and invertebrates)

Acute Potential for effects to non-listed animals from acute 

exposures

Peak EEC/LC501

0.5

Acute 

Restricted Use

Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use classification

Peak EEC/LC501

0.1

Acute Listed 

Species

Listed species may be potentially affected by acute 

exposures

Peak EEC/LC501

0.05

Chronic Potential for effects to non-listed and listed animals from 

chronic exposures 

60-day EEC/NOAEC 

(fish) 1

21-day EEC/NOAEC 

(invertebrates)

Aquatic Plants

Non-Listed Potential for effects to non-listed plants from exposures Peak EEC/EC50 1

Listed Potential for effects to listed plants from exposures Peak EEC/NOAEC or 

EC052 1

Terrestrial Animals (mammals and birds)

Acute Potential for effects to non-listed animals from acute 

exposures

EEC/LC50 (Dietary) 0.5

EEC/LD50 (Dose)

Acute 

Restricted Use

Potential for effects to animals from acute exposures

Risks may be mitigated through restricted use classification

EEC/LC50 (Dietary) 0.2

EEC/LD50 (Dose)

Acute Listed 

Species

Listed species may be potentially affected by acute 

exposures

EEC/LC50 (Dietary) 0.1

EEC/LD50 (Dose)

Chronic Potential for effects to non-listed and listed animals from 

chronic exposures EEC/NOAEC 1

Terrestrial Invertebrates

Acute Listed 

Species

Listed species may be potentially affected by acute 

exposures

EEC/LD50 0.05

Terrestrial and Semi-Aquatic Plants

Non-Listed Potential for effects to non-target, non-listed plants from 

exposures

EEC/ EC25 1

Listed Plant Potential for effects to non-target, listed plants from 

exposures

EEC/ NOAEC or 

EC052 1

1 LC50 or EC50. 2 An EC05 is used when a NOAEC is not available

7.5. Effects to Aquatic Organisms

The most sensitive of the available aquatic toxicity data from registrant-submitted studies are 

provided in Table 6. Any studies available in ECOTOX will be reviewed for the risk 
21

assessment. There are no data for shell deposition and no chronic data for estuarine/marine fish 

and invertebrates, although the lack of toxicity to freshwater organisms suggests these data are 

not necessary for risk assessment. Based on the available information, primisulfuron methyl is 

classified as practically nontoxic to freshwater and estuarine/marine fish and freshwater

invertebrates and slightly toxic to estuarine/marine invertebrates on an acute exposure basis. 

Available data indicate both vascular and nonvascular aquatic plants are affected by 

primisulfuron methyl. 

There are no aquatic toxicity data available for degradate CGA-171683.

Table 6. Most Sensitive Aquatic Toxicity Profile for Primisulfuron Methyl

Taxonomic Group Surrogate Species

(Common Name)

Endpoint

(mg ai/L) Acute Classification Reference(MRID)

Freshwater Fish

Oncorhynchus mykiss

(rainbow trout) LC50=210 Practically nontoxic 41781502

Pimephales promelas

(fathead minnow) NOAEC=11 a -- 41418608

Freshwater 

Invertebrates

Daphnia magna

(daphnid shrimp)

EC50>100 Practically nontoxic 41418605

NOAEC=0.41 -- 41418609

Estuarine/marine 

Fish

Cyprinodon variegatus

(sheepshead minnow) LC50>100 Practically nontoxic 41418606

Estuarine/marine 

Invertebrates

Mysidopsis bahia

(mysid shrimp) EC50=16 Slightly toxic 41418607

Vascular plants Lemna gibba

(duckweed)

EC50=0.0008

NOAEC=0.0004 --b 40520102

Nonvascular plants Anabaena flos-aquae

(Cyanobacteria)

EC50=0.098

NOAEC=0.055 --b 42147902

a No effects were observed at the highest dose tested. The LOAEC is >11 mg a.i./L

b Toxicity categories for plants have not been defined.

7.6. Effects to Terrestrial Organisms

Table 7 summarizes the most sensitive terrestrial toxicity endpoints for primisulfuron methyl, 

based on an evaluation of the submitted data. If open literature studies are identified through 

ECOTOX, they will be reviewed for the risk assessment. Primisulfuron methyl is classified as 

practically nontoxic to terrestrial birds on a subacute dietary exposure basis; acute oral data for 

passerines is necessary to fully evaluate the risks to all birds including the smaller passerine 

species exposed primisulfuron methyl via the oral route. Primisulfuron methyl is classified as 

practically nontoxic to mammals on an acute oral exposure basis. Primisulfuron methyl is 

classified as practically nontoxic to honey bees (Apis mellifera) on an acute contact exposure 

basis. No toxicity category for terrestrial plants is available; however, primisulfuron methyl is 

quite toxic to terrestrial plants. 

There are no terrestrial toxicity data available for degradate CGA-171683.

Table 7. Most Sensitive Terrestrial Toxicity Profile for Primisulfuron Methyl

Taxonomic 

Group

Surrogate Species

(Common Name) Endpoint Acute Classification/ Chronic effect Reference (MRID)
22

Taxonomic 

Group

Surrogate Species

(Common Name) Endpoint Acute Classification/ Chronic effect Reference (MRID)

Birds

Anas platyrhynchos

(Mallard duck)

LD50>2150 mg ai/kgbw Practically nontoxica 40331251a

LC50>5000 mg ai/kg 

diet Practically nontoxic 40331252

NOAEC=500 mg ai/kgdietb -- 40512004

Mammals Rattus norvegicus

(Laboratory rat)

LD50>5050 mg ai/kgbw Practically non toxic 00403312

Laboratory rat

LOAEL=5000 mg 

ai/kg-diet

NOAEC=1000 mg 

ai/kg-diet

Reduced pup weight 40512009

Terrestrial 

Invertebrates

Apis mellifera

(Honey bee) LD50>100 μg ai/bee Practically nontoxic 41364002

Seedling 

emergence

Monocot: Onion EC25=0.0015 lb/A

NOAEC=0.00027 lb/Ac

--d 40856505

Dicot: Tomato EC25=0.0002

NOAEC=0.0027c

Vegetative 

vigor

Monocot: Onion EC25=0.00057 lb/A

NOAEC=0.00045 lb/A --d 40856506

Dicot: Carrot EC25=0.0002 lb/A

NOAEC<0.0001 lb/Ac

a Data are incomplete pending passerine submission b No effects were observed at the highest dose tested, the LOAEC is >500 mg a.i./kg. c The NOAEC is unreliable; an EC05 value will be used as a surrogate; however, the unavailable EC05s will be

calculated prior to the risk assessment. d Toxicity categories for plants have not been defined.

Although avian subacute and mammalian acute endpoints are nondefinitive values, preliminary 

calculation of RQs (not shown) indicate that the highest dose tested (e.g. 5000 mg ai/kg-bw) are 

sufficiently higher than the EECs that further data are not needed at this time.

Deterministic and Probabilistic Assessment Methods

The quantitative assessment of risk will primarily depend on the deterministic point-estimate 

(RQ) based approach described in the risk assessment. An effort will be made to further 

qualitatively describe risk using probabilistic tools that the Agency has developed. These tools 

have been reviewed by FIFRA Scientific Advisory Panels 

(http://www.epa.gov/scipoly/sap/index.htm) and have been deemed as appropriate means of 

refining assessments where deterministic approaches have identified risks. Newer tools may be 

available to assess the routes of exposure (e.g. TIM and SWAMP models) and will be applied as 

appropriate in Registration Review.

7.7. Endocrine Disruptor Screening Program
23

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (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.

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. 

This list of chemicals was selected based on the potential for human exposure through pathways 

such as food and water, residential activity, and certain post-application agricultural scenarios. 

This list should not be construed as a list of known or likely endocrine disruptors.

Primisulfuron methyl is not among the group of 58 pesticide active ingredients on the initial list 

to be screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all pesticide 

chemicals. Accordingly, EPA anticipates issuing future EDSP test orders/data call-ins for all 

pesticide active ingredients. 

For further information on the status of the EDSP, the policies and procedures, the list of 67 

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

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

7.8. Federally-listed Endangered and Threatened Species Assessment

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the 

Agency will evaluate risks to Federally-listed threatened and/or endangered (listed) species from 

registered uses of primisulfuron methyl. This assessment will be conducted in accordance with 

the Overview Document (USEPA 2004), provisions of the ESA, and the Services’ Endangered 

Species Consultation Handbook (USFWS/NMFS, 1998).

The assessment of effects associated with the registration of primisulfuron methyl is based on an 

action area. The action area is considered to be the area directly or indirectly affected by the 

federal action, as indicated by the exceedance of Agency Levels of Concern (LOCs) used to 

evaluate direct or indirect effects. The Agency’s approach to defining the action area under the 

provisions of the Overview Document (USEPA 2004) considers the results of the risk 

assessment process to establish boundaries for that action area with the understanding that 

exposures below the Agency’s defined LOCs constitute a no-effect threshold. For the purposes 

of this assessment, attention will be focused on the footprint of the action (i.e., the area where 

primisulfuron methyl application occurs), plus all areas where offsite transport (i.e., spray drift, 
24

runoff, etc.) may result in potential exposure that exceeds the Agency’s LOCs. Specific 

measures of ecological effect that define the action area for listed species include any direct and 

indirect effects and/or potential modification of its critical habitat, including reduction in 

survival, growth, and reproduction as well as the full suite of sublethal effects available in the 

effects literature. Therefore, the action area extends to a point where environmental exposures 

are below any measured lethal or sublethal effect threshold for any biological entity at the whole 

organism, organ, tissue, and cellular level of organization. In situations where it is not possible 

to determine the threshold for an observed effect, the action area will initially be assumed to 

include all counties where primisulfuron methyl is used in the United States. 

7.9. Drinking Water Assessment

A drinking water assessment will be conducted to support future human health dietary risk 

assessments of primisulfuron methyl. The drinking water exposure assessment will be 

conducted for the maximum labeled use in support of the human health dietary risk assessment. 

The drinking water assessment will incorporate model estimates of primisulfuron methyl alone in 

surface water and ground water including any residues that are determined to be of toxicological 

concern. Concentrations of primisulfuron methyl in surface waters will be estimated using 

PRZM/EXAMS (see description above) but using the Index Reservoir scenario rather than the 

standard pond used with aquatic exposure assessment.

An Estimated Drinking Water Concentration (EDWC) of primisulfuron methyl in ground water 

will be estimated using EFED’s Tier I aquatic model SCIGROW (Screening Concentration in 

Ground Water). SCIGROW is a regression model used as a screening tool to estimate pesticide 

concentrations found in ground water used as drinking water. The output of SCIGROW 

represents the concentrations that might be expected in shallow unconfined aquifers under sandy 

soils, which is representative of the ground water most vulnerable to pesticide contamination 

likely to serve as a drinking water source. 

The drinking water assessment will also include available surface and groundwater monitoring 

data with consideration of changes in use patterns that may have occurred. States are encouraged 

to submit monitoring data for review.

7.10. Environmental Monitoring Data

Primisulfuron methyl has not been included for analysis in United States Geological Survey’s 

(USGS) National Water Quality Assessment Program (NAWQA) or in the California 

Department of Pesticide Regulations (DPR) monitoring program, however other sulfonylurea 

herbicides have been included for NAWQA analysis and have been detected in surface water and 

ground water (e.g. bensulfuron). A prospective groundwater study has been performed for 

primisulfuron methyl find that it is highly mobile and is potentially persistent in lower soil layers 

(MRID 42585001). While environmental fate properties and use patterns may differ, this 

indicates the potential for herbicides similar to primisulfuron methyl to be present in surface and 

ground waters.
25

8.0. Preliminary Identification of Data Gaps

8.1. Environmental Fate

The studies submitted to fulfill environmental fate data requirements for primisulfuron methyl

are not sufficient to conduct an exposure assessment; four data requirements have not been met 

as stipulated by 40 CFR part 158 Subpart N §158.1300 for all pesticides with use patterns for 

terrestrial and nonfood applications. These studies will decrease uncertainty in determining the 

potential exposure to the pesticide: 

• Submission of an acceptable aerobic aquatic metabolism (OPPTS guideline # 835.4300) 

study is necessary to understand the degradation of primisulfuron methyl in oxygen 

abundant aquatic environments. The guideline stipulates that at least two different 

sediment:water systems be submitted that are similar to the potential use sites in the 

United States. In the absence of this data, the model input for aerobic soil metabolism is 

doubled to conservatively estimate the model input for aerobic aquatic metabolism.

• Submission of an acceptable anaerobic aquatic metabolism (OPPTS guideline # 

835.4400) study is necessary to understand the degradation of primisulfuron methyl in 

oxygen-limiting environments. In the absence of this data, the model input for anaerobic 

soil metabolism is doubled to conservatively estimate the model input for anaerobic 

aquatic metabolism.

• There are currently terrestrial field dissipation studies (OPPTS guideline # 835.6100) 

under review by the Agency. Until the review is complete, EFED cannot be certain the 

data are sufficient for risk assessment. This study is necessary to understand the 

dissipation of primisulfuron methyl in field conditions.

• Supplemental to the terrestrial field dissipation studies are the independent laboratory

method validation, and environmental chemistry methods used for the field study. 

Table 8 identifies studies by MRID that offer data for each guideline requirement, as well as 

study classifications and whether or not further data are needed in order to support risk 

assessment (i.e., whether there is a data gap).

Table 8. Summary of available environmental fate data for primisulfuron methyl and its 

degradates.

Guideline Study Title MRID / 

ACC No. Classification Data Gap? Comments

835.2120 Hydrolysis

40331261 Acceptable

No

This study is acceptable. No hydrolysis observed at 

pH 7 and 9, long half-life (>30 days) was observed 

for pH 5. 

40856507 Supplemental The test at pH 5 had unacceptable material balance. 

At pH 7 and pH 9, the compound was stable.

835.2240 Photodegradation 

in Water

40331262 Supplemental

No 40856508 Supplemental The compound did not photodegrade in sunlight in 

pH 5 and pH 9 solutions.

41418611 Acceptable The compound did not photodegrade in sunlight in 

pH 9 solutions.

835.2410 Photodegradation 40856420 Unacceptable No Parent and degradate not positively identified
26

Guideline Study Title MRID / 

ACC No. Classification Data Gap? Comments

on Soil 40856421 Unacceptable The TLC methodology was not demonstrated to be 

adequate

41418612 Acceptable

Degradation occurred with half lives of 24.2 days 

and 26.0 days on sunlight-irradiated and dark control 

samples respectively indicating that degradation was 

due to chemical processes other than photolysis.

835.4100 Aerobic Soil 

Metabolism

40331263 Supplemental

No

Major degradates were not identified. Parent 

compound degraded with a half-life of 63 days.

40856511 In Review

41418613 Acceptable

Study conducted with pyrimidine-labeled compound 

with a half life of 30 days. This study satisfies the 

need for an aerobic soil metabolism study.

835.4200 Anaerobic Soil 

Metabolism

40331263 Acceptable

No

Study conducted with phenyl-labeled compound with 

a half life of 89 days. This study satisfies the need for 

an anaerobic soil metabolism study.

40856511 In Review

41418614 Acceptable

Study conducted with phenyl-labeled compound with 

a half life of 41 days. This study satisfies the need for 

an anaerobic soil metabolism study.

835.4300 Aerobic Aquatic 

Metabolism No Data No Data Yes

In the absence of submitted data, it will be 

conservatively assumed that the aerobic aquatic 

metabolism half-life is two times the estimate of the 

aerobic soil metabolism half-life. The value of this 

data is low because the assumption made is 

sufficiently conservative.

835.4400

Anaerobic 

Aquatic 

Metabolism

No Data No Data Yes

In the absence of submitted data, it will be 

conservatively assumed that the anaerobic aquatic 

metabolism half-life is two times the estimate of the 

anaerobic soil metabolism half-life. The value of this 

data is low because the assumption made is 

sufficiently conservative.

835.1240

Mobility - 

Adsorption / 

Desorption

40331264 Acceptable

No

Soil column leaching study. Additional 

characterization for aged soils is needed. Further 

mobility on the triazine moiety is needed to 

characterize the mobility of the parent and major 

degradates.

40856513 Acceptable This soil column leaching study found 72.5-73.7% of 

radioactivity applied to soil columns in leachate

40856514 Invalid

This soil column leaching found greater amounts of 

primisulfuron methyl at study conclusion than at 

study initiation. 
27

Guideline Study Title MRID / 

ACC No. Classification Data Gap? Comments

41869302 Acceptable

This aged column leaching study found the residues 

of pyrimidine-labeled primisulfuron methyl to be 

very mobile. 

41869303 Acceptable

This aged column leaching study found the residues 

of phenyl-labeled primisulfuron methyl to be very 

mobile. 

41869304 Acceptable

This aged column leaching study found the residues 

of phenyl-labeled primisulfuron methyl to be very 

mobile. 

41869305 Acceptable This aged column leaching study found the residue 

CGA-120844 to be very mobile. 

41869306 Acceptable This aged column leaching study found the residue 

CGA-171683 to be very mobile. 

41869307 Acceptable This aged column leaching study found the residue 

CGA-177288 to be very mobile. 

41869308 Acceptable This aged column leaching study found the residue 

CGA-191429 to be very mobile. 

41869309 Acceptable This aged column leaching study found the residue 

CGA-27913 to be very mobile. 

835.6100 Terrestrial Field 

Dissipation 

40512015 Supplemental

Yes1

These studies provide data on dissipation of parent 

primisulfuron methyl but does not address the pattern 

of formation and decline of degradates

40512016 Supplemental

40512017 Supplemental

40512018 Supplemental

40512019 Supplemental

40856515 Unacceptable

Primisulfuron methyl comprised only 51-81% of 

radioactivity at time 0. Also, the analytical method 

used was nonspecific and did not distinguish 

residues.

43263203 In Review If these studies do not fulfill the data requirement, 

field dissipation of of primisulfuron methyl cannot be 

adequately characterized and laboratory data will be 

conservatively interpreted for risk characterization 

purposes. The value of this data is moderate.

43263204 In Review

43263205 In Review

43263206 In Review

850.1730 Fish BCF R2072317 Data Waiver No

1 Environmental chemistry methods used to generate data associated with this study must include results of a successful 

confirmatory method trial by an independent laboratory. Test standards and procedures for independent laboratory 

validation are available as addenda to the guideline for this test requirement.

8.2. Effects

The available ecological effects dataset for primisulfuron methyl and its degradates is considered 

incomplete. 

There are no data on the effect of primisulfuron methyl on shell deposition or on the chronic 

effects on reproduction and growth of estuarine/marine species; although the toxicity to 

freshwater species is two orders of magnitude higher than the estimated EEC suggests that these 

data with estuarine/marine species would not affect risk conclusions. The value for these data 

with primisulfuron methyl is low. 
28

There are no data with primisulfuron methyl for acute oral effects on passerine species; 

according to 40 CFR 158, a study with a passerine exposed to the TGAI is necessary for risk 

assessment to fully evaluate the acute effects to all birds including the smaller passerine species 

on an acute oral basis. Although there are no effects observed in the available mallard duck and 

bobwhite quail studies, studies have shown nestling passeriformes and breeding females to be 

more sensitive to certain pesticides than adult males and nonbreeding females (Minneau 1996). 

In addition, the Scientific Advisory Panel (SAP 1996)1 recommends including passerine birds to 

consider the differential sensitivity associated with age or gender of the test birds, especially 

altricial nestlings and breeding adults. The value for the passerine acute oral toxicity study with 

primisulfuron methyl is medium.

Terrestrial plants are typically very sensitive to sulfonylurea urea herbicide exposure. There is 

evidence2 to suggest plant reproduction may be affected by sulfonylurea herbicides at levels 

below effects on vegetative growth or visual injury (Fletcher et al., 1993). Uncertainty regarding 

the potentially greater sensitivity of terrestrial plant reproduction has been discussed extensively 

in the environmental fate and effects RED assessment for chlorsulfuron (D330621). Therefore, 

to the extent that terrestrial plant reproduction is more sensitive to primisulfuron methyl than 

growth endpoints, risks to terrestrial plants may be underestimated in this risk assessment. 

Additional information on the reproductive toxicity of primisulfuron methyl to terrestrial plants 

would help address this uncertainty. The value for the terrestrial plant reproduction study with 

primisulfuron methyl is high.

Toxicity and risk from primisulfuron methyl degradate CGA-171683 is an area of significant 

uncertainty. As discussed in the environmental fate section (Section 3.3), the major degradate, 

CGA-171683, is persistent and will remain in the soil after the parent has degraded (present at 

75% of applied concentration at 12 months and in anaerobic soil reaching 75% of applied 

radioactivity at 3 months, yet there are no data on CGA-171683. There is an exposure concern 

for CGA-171683 to affect the reproduction in birds due to the potential mobility and persistence, 

the Agency is asking for an avian reproduction study with bobwhites and mallards exposed to the 

degradate CGA-171683; the value for the data is high. 

For all other taxonomic groups exposed to CGA-171683, the value for the degradate data is low 

since the preliminary assessment, “degradate toxicity comparison” (Appendix D) concluded that 

the predicted toxicity of CGA-171683 from the QSAR analysis with a surrogate chemical is near 

that of parent primisulfuron methyl. Because exposure is too low to trigger the Level of Concern 

(LOC), by two orders of magnitude, it is unlikely that additional toxicity data for the degradates 

will alter the risk conclusions for parent primisulfuron methyl.

 1 Scientific Advisory Panel (1996). A set of Scientific Issues Being Considered by the Agency in Connection with 

EPA’s Ecological Risk Assessment of Carbofuran Flowable Products and with EPA’s Corn Cluster Ecological Risk 

Assessment. Review conducted in an open meeting held on May 29 – 31. Pages 37-49. 2 Snipes et al. 1992, Bansal et al. 1999; Fletcher et al. 1993, 1995,1996; Bhatti et al. 1995; Al-Khatib et al. 1992; 

Boutin et al. 2000; Asghari and Evans 1992
29

The available effects studies for primisulfuron methyl and degradate CGA-171683 are presented 

in Tables 9-12. The following data gaps are identified below. 

• Primisulfuron methyl - OPPTS 850.2100; An avian acute oral study with a passerine is 

necessary for risk assessment. Until the data is available, EFED cannot be certain the 

data are sufficient for an ecological risk assessment on birds.

• Primisulfuron methyl - Non-guideline; Terrestrial Plant Reproduction Study will be 

necessary for risk assessment to fully evaluate the effects of primisulfuron methyl to 

plants at different stages.

• Degradate CGA171683 - OPPTS 850.2300; reproduction toxicity to upland game bird 

and waterfowls. Toxicity data on the environmental relevant degradate CGA171683 of 

primisulfuron methyl is necessary for risk assessment since CGA171683 is persistent in 

the environment with 75% of the degradate remaining after 12 months.

TABLE 9. Available ecological effects data for terrestrial animals exposed to 

primisulfuron methyl

Guideline Description MRID/

Accession Classification Data Gap? Comments

850.2100

Avian oral toxicityUpland game bird 

and waterfowl

40331250

40331251

Acceptable

Acceptable

Yes1

1

Avian acute oral toxicity data 

are not available for passerine 

species. Data are needed to 

fully evaluate the effects of 

primisulfuron methyl to all 

birds including the smaller, 

passerine, species. The value 

for the passerine acute oral 

data with primisulfuron 

methyl is high.

2 Avian reproduction toxicity 

data are not available for 

upland game birds; however, 

no reproduction effects to 

mallards occurred at the 

highest level tested and no 

acute effects to mallards and 

quails occurred at the highest 

level test, there are sufficient 

data to assess the chronic 

effects on birds. The value for 

the quail reproduction data 

with primisulfuron methyl is 

low.

Avian oral toxicity –

passerines No data --

850.2200 Avian dietary 

toxicity 

40331252

40331253

Acceptable 

Acceptable No

850.2300 Avian reproduction 40512003

40512004

Invalid

Acceptable Yes2

850.3020 Honeybee acute 

contact toxicity 41364002 Acceptable No

TABLE 10. Available ecological effects data for aquatic animals exposed to primisulfuron

methyl.
30

Guideline Description MRID/ 

Accession Classification Data Gap? Comments

850.1075 Freshwater fish –

Acute toxicity 

40331254

40331255

41418603

41418604

41781501

41781502

Invalid

Supplemental

Supplemental

Supplemental

Acceptable

Acceptable

No

1 Although acute 

estuarine/marine data for 

Eastern oyster (shell 

deposition) and chronic 

estuarine/marine data for 

sheepshead minnow and 

mysid shrimp are unavailable 

for primisulfuron methyl, the 

lack of toxicity with other 

aquatic organisms (e.g., 

fathead minnow ELS, embryolarval acute and mysid shrimp

acute); in addition, the lowest

aquatic organism value is 

approximately two orders of 

magnitude above the EEC that 

would result in a chronic 

effect to daphnids, suggest

these data are unnecessary for 

the risk assessment. The value 

for these estuarine/marine 

species data with 

primisulfuron methyl is low.

850.1075

Estuarine/marine

fish –

Acute toxicity 

40331257

41418606

Invalid

Acceptable No

850.1010

Freshwater 

invertebrates –

Acute toxicity

40331256

41418605

Supplemental

Acceptable No

850.1025

850.1035

850.1055

Estuarine/marine 

invertebrates –Acute 

toxicity 

40331258

40331259

41364001

41418607

Invalid

Supplemental

Acceptable

Acceptable

Yes1

850.1300

Freshwater 

invertebrate –

life cycle test

40512006

41418609

Invalid

Acceptable No

850.1350

Estuarine/marine

invertebrates –

life cycle test

No data -- Yes1

850.1400 Freshwater fish –

early life stage test

40512005

41418608

Invalid

Supplemental No

850.1400

Estuarine/marine

fish –

early life stage test

No data -- Yes1

TABLE 11. Available ecological effects data for plants exposed to primisulfuron methyl.

Guideline Description MRID Classification Data 

Gap? comments

850.4100 

Terrestrial Plant 

toxicity: Tier I and II 

seedling emergence

40512011

40856505

Acceptable

Acceptable No

850.4150 

Terrestrial Plant 

toxicity: Tier I and II

vegetative vigor

40512010

40856506

Acceptable

Acceptable No

850.5400 Aquatic Plant Growth: 

algae

40520101

42147901

42147902

42147903

Acceptable

Acceptable

Acceptable

Acceptable

No

850.4400 Aquatic Plant Growth: 

vascular plants 40520102 Acceptable No
31

TABLE 12. Available ecological effects data for animals and plants exposed to CGA171683.

Guideline Description MRID Classification Data Gap? comments

850.2300 Avian reproduction No data -- Yes1

1

Degradate CGA-171683 

toxicity data on the effect 

of reproduction to birds is

needed to fully evaluate 

the effects of the 

degradate to the 

environment due to its 

mobility and persistence. 

The value for the data 

with CGA-171683 is high.

850.4100 

Terrestrial Plant 

toxicity: Tier I and/or 

Tier II seedling 

emergence

No data -- Yes2

2 Primisulfuron methyl is 

quite toxic to terrestrial 

plants, it is unlikely risk 

conclusions would be 

altered with degradate 

data. The value for the 

data is low.

850.1075 Freshwater Fish: 

acute toxicity No data --

Yes3

The QSAR analysis with a 

surrogate chemical 

suggests that the toxicity 

of the degradate is almost 

the same as that of parent 

primisulfuron methyl 

which is two orders of 

magnitude higher than the 

EEC to result in an effect. 

It is likely that the 

additional data with the 

degradate would not alter 

the risk conclusions for 

parent primisulfuron 

methyl. The value for the 

data is low.

850.1400 Freshwater Fish: early 

life stage test No data --

850.1010

Freshwater 

Invertebrate: acute 

toxicity

No data --

850.1300

Freshwater 

Invertebrate: life-cycle 

test

No data --

850.5400 Aquatic Plant Growth: 

algae No data --

850.4400 Aquatic Plant Growth: 

vascular plants No data --

8. Other Information Needs

There is specific information that will assist the Agency in refining the ecological risk 

assessment, including any species-specific effects determinations. The Agency is very much 

interested in obtaining the following information:

1. confirmation on the following label information

a. frequency of application, application intervals, and maximum number of 

applications per season

b. geographic limitations on use

2. use or potential use distribution (e.g., acreage and geographical distribution of relevant 

crops)

3. use history
32

4. median and 90th percentile reported use rates (lbs. a.i./acre) from usage data – national, 

state, and county

5. application timing (date of first application and application intervals) by crop – national, 

state, and county

6. sub-county crop location data

7. directly acquired county-level usage data (not derived from state level data)

a. maximum reported use rate (lbs. a.i./acre) from usage data – county

b. percent crop treated – county

c. median and 90th percentile number of applications – county

d. total pounds per year – county

e. the year the pesticide was last used in the county/sub-county area

f. the years in which the pesticide was applied in the county/sub-county area

8. state or local use restrictions

9. ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the Agency

10. monitoring data 

9. References

Open Literature Citations

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the 

EPA food-chain (Kenaga) nomogram, an instrument for estimating pesticide residues on 

plants. Environ. Tox. Chem. 13:1383-1391.

Hoerger, F., and E.E. Kenaga. 1972. Pesticide residues on plants: Correlation of representative 

data as a basis for estimation of their magnitude in the environment. In F. Coulston and 

F. Korte, eds., Environmental Quality and Safety: Chemistry, Toxicology, and 

Technology, Georg Thieme Publ, Stuttgart, West Germany, pp. 9-28.

Nakata, M. 1991. The mode of action of chlorsulfuron in culture cells of tobacco and hamster. J. 

Pest. Sci. 16:583-590

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS). 1998. 

Endangered Species Consultation Handbook: Procedures for Conducting Consultation 

and Conference Activities Under Section 7 of the Endangered Species Act. Final Draft. 

March 1998.

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and 

Toxic Substances, Office of Pesticide Programs, Washington DC. January 23, 2004.

USEPA. 1998. Guidelines for Ecological Risk Assessment. Risk Assessment Forum, Office of 

Research and Development, Washington, D.C. EPA/630/R-95/002F. April 1998. 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=30759
33

Willis, G.H. and L.L. McDowell. 1987. Pesticide Persistence on Foliage in Reviews of 

Environmental Contamination and Toxicology. 100:23-73.

USDA-NASS (United States Department of Agriculture’s National Agricultural Statistic 

Service) Private Pesticide Market Research.

Review of Emergency Exemption Requests from Washington and Idaho for Use of

Primisulfuron methyl Herbicide to Control Weeds in Kentucky Bluegrass Grown for 

Seed (98-ID-09, 98-WA-08), DP barcodes D243385 through D243388; Anderson, Neil, 

and Halverson,Alan, 4/08/98.

Scientific Advisory Panel (1996). A set of Scientific Issues Being Considered by the Agency in 

Connection with EPA’s Ecological Risk Assessment of Carbofuran Flowable Products 

and with EPA’s Corn Cluster Ecological Risk Assessment. Review conducted in an open 

meeting held on May 29 – 31. Pages 37- 49.

Submitted Fate Studies

161-1 Hydrolysis

MRID Citation Reference

40331261 2072326

2072316= 

study report

Obrist, J. (1987) Hydrolysis of Phenyl-[Carbon 14]-CGA-136872 in Water: 

Final Report: Laboratory Project ID: 6015-260A. Unpub- lished study 

prepared by Hazleton Laboratories America, Inc. 80 p. 

40512013 2072325= 

summary

Rhoads, W. (1987) Determination of The Hydrolysis Rate Constants of CGA136872 Using Pyrimidine ?Carbon 14|-labeled CGA-136872: Laboratory 

Study Number 1062. Unpublished study prepared by Colorado Analytical 

Research & Development Corporation. 60 p. 

40856507 2072351

2072325= 

summary

Rhoads, W. (1988) Determination of the Hydrolysis Rate Constants of CGA136872 Using Pyrimidine ?carbon 14|-Labeled CGA-136872: Stu- dy No. 

1062. Unpublished study prepared by Colorado Analytical Research and 

Development Corp. 66 p. 

43263201 Kesterson, A. (1994) Hydrolysis of Phenyl-(carbon-14)-CGA 136872 at pH, 7 

and 9: Lab Project Number: 442. Unpublished study prepared by PTRL East, 

Inc. 85 p. 

43263202 Kesterson, A. (1994) Hydrolysis of Pyrimidinyl-(carbon-14)-CGA 136872 at 

pH, 7 and 9: Lab Project Number: 443. Unpublished study prepared by PTRL 

East, Inc. 85 p. 

161-2 Photodegradation-water

MRID Citation Reference
34

40331262 2072311= 

summary

2072319= 

study report

Obrist, J. (1987) Photodegradation of Phenyl-[Carbon 14]-CGA-136872 in 

Water: Final Report: Laboratory Project ID: 6015-260B. Un- published study 

prepared by Hazleton Laboratories America, Inc. 128 p. 

40512014 See 

40856509

Rhoads, W. (1987) Determination of the Aqueous Photolysis Characteristics 

of CGA-136872 Under Natural and Artificial Light using Pyrimidine ?Carbon 

14|-CGA-136872: Laboratory Study No. 1060. Unpublished study prepared 

by Colorado Analytical Research & Development Corporation. 191 p. 

40856508 2072352

2072353

2072325= 

summary

Lawrence, L. (1988) Solution Photolysis of CGA-136872 Under Natural 

Sunlight Conditions: Study No. 211. Unpublished study prepared by 

Pharmacology & Toxicology Research Laboratory. 94 p. 

40856509 2072354

2072355

Rhoads, W. (1988) Determination of the Aqueous Photolysis Characteristics 

of CGA-136872 Under Natural and Artificial Light using Pyrimidine ?Carbon 

14|-CGA-136872: Laboratory Study No. 1060. Unpublished study prepared 

by Colorado Analytical Research & Development Corporation. 191 p.

40856510 Supplement 

to 

40331262

Obrist, J. (1987) A Supplement to the Report Photodegradation of Phenyl-

?carbon 14|-CGA-136872 in Water. Unpublished study pre- pared by CibaGeigy Corp. 18 p. 

41418611 2072360

2072325= 

summary

Lawrence, B.; Kesterson, B.; Marsh, J.; et al. (1989) Solu- tion Photolysis of 

Pyrimidinyl-?Carbon 14|CGA-136872 in Natural Sunlight at pH 9: Final 

Report Re-Issue: Lab Project Number: 286. Unpublished study prepared by 

Pharmacology and Toxicology Research Laboratory. 82 p. 

161-3 Photodegradation-soil

MRID Citation Reference

40856420 2072346

2072348

2072325= 

summary

Lawrence, L. (1988) CGA-136872: Soil Surface Photolysis of CGA- 136872 

in Natural Sunlight: Laboratory Project No. 223. Unpub- lished study 

prepared by Pharmacology & Toxicology Research Laboratory. 58 p. 

40856421 2072349 Rhoads, W. (1988) CGA-136872: Determination of the Soil Photolysis 

Characteristics of CGA-136872 under Natural and Artificial Light using 

Pyrimidin ?Carbon 14|-Labeled CGA-136872: Laboratory Study No. 1061. 

Unpublished study prepared by Colorado Analytical Research and 

Development Corp. 93 p. 

41418612 2072361

2072325= 

summary

Jackson, S.; Kesterson, A.; Lawrence, L. (1989) Soil Surface Photo- lysis of 

Pyrimidinyl-?Carbon 14|-CGA-136872 in Natural Sunlight: Final Report Reissue: Lab Project Number: 287. Unpublished study prepared by Ciba-Geigy 

Corp. 69 p. 

162-1 Aerobic soil metabolism
35

MRID Citation Reference

40331263 2072327

2072328

2072315= 

study report

Obrist, J. (1987) Aerobic, Aerobic/Anaerobic, and Sterile Soil Met- abolism of 

Phenyl-[Carbon 14]-CGA-136872: Final Report: Labora- tory Project ID: 

6015-262. Unpublished study prepared by Hazle- ton Laboratories America, 

Inc. 146 p. 

40856511 DER not 

located

Rhoads, W. (1988) Environmental Fate Study for the Aerobic, 

Aerobic/Anaerobic and Sterile Soil Metabolism of Pyrimidine- ?carbon 14|-

CGA-136872: Study No. 1066. Unpublished study pre- pared by Colorado 

Analytical Research & Development Corp. 167 p. 

40856512 2072327

2072328

Obrist, J. (1987) A Supplement to Aerobic, Aerobic/Anaerobic, and Sterile 

Soil Metabolism of Phenyl-?carbon 14|-CGA-136872. Unpu- blished study 

prepared by Ciba-Geigy Corp. 31 p. 

41418613 2072362

2072325= 

summary

2072326

Olson, G.; Lawrence, L.; Lawrence, M. (1990) Aerobic Metabolism of 

?Carbon 14|-CGA-136872 in Sandy Loam Soil: Lab Project Number: 1242: 

288. Unpublished study prepared by Pharmacology and Toxi- cology 

Research Laboratory. 189 p. 

41418613-B 2072347 Olson, G.; Lawrence, L.; Lawrence, M. (1990) Aerobic Metabolism of 

?Carbon 14|-CGA-136872 in Sandy Loam Soil: Lab Project Number: 1242: 

288. Unpublished study prepared by Pharmacology and Toxi- cology 

Research Laboratory. 189 p.

162-2 Anaerobic soil metabolism

MRID Citation Reference

40331263 2072311 and 

2072325 = 

summary

2072315= 

study report

Obrist, J. (1987) Aerobic, Aerobic/Anaerobic, and Sterile Soil Met- abolism of 

Phenyl-[Carbon 14]-CGA-136872: Final Report: Labora- tory Project ID: 

6015-262. Unpublished study prepared by Hazle- ton Laboratories America, 

Inc. 146 p. 

40856511 DER not 

located

Rhoads, W. (1988) Environmental Fate Study for the Aerobic, 

Aerobic/Anaerobic and Sterile Soil Metabolism of Pyrimidine- ?carbon 14|-

CGA-136872: Study No. 1066. Unpublished study pre- pared by Colorado 

Analytical Research & Development Corp. 167 p. 

40856512 2072325= 

summary

Obrist, J. (1987) A Supplement to Aerobic, Aerobic/Anaerobic, and Sterile 

Soil Metabolism of Phenyl-?carbon 14|-CGA-136872. Unpu- blished study 

prepared by Ciba-Geigy Corp. 31 p. 

41418614 2072364

2072325= 

summary

Olson, G.; Lawrence, L.; Lawrence, M. (1990) Anaerobic Metabolism of 

?Carbon 14| CGA-136872 in Sandy Loam Soil: Lab Project Num- ber: 1206: 

289. Unpublished study prepared by Pharmacology and Toxicology 

Research Laboratory. 58 p. 
36

163-1 Leach/adsorp/desorption

MRID Citation Reference

40331264 2072311= 

summary

2072313= 

study report

Spare, W. (1986) Determination of the Leaching Potential of CGA- 136872 

Using Soil Thin-layer Chromatography: Laboratory Study No. 1225. 

Unpublished study prepared by Agrisearch, Inc. 54 p. 

40331265 2072329

2072330

2072318= 

study report

Spare, W. (1986) Leaching Characteristics of Parent CGA-136872: 

Laboratory Study No. 1224. Unpublished study prepared by Agri- search, Inc. 

68 p. 

40331266 2072330 Saxena, A. (1986) Leaching Characteristics of CGA-136872 Aged in Soil: 

Laboratory Study No. 6015-263. Unpublished study prepared by Hazleton 

Laboratories America, Inc. 49 p. 

40331267 2072311= 

summary Spare, W. (1986) Determination of Adsorption/Desorption Constants of CGA136872: Laboratory Study No. 1223. Unpublished study prepared by 

Agrisearch, Inc. 63 p. 

40856513 2072356

2072357

Saxena, A. (1988) Leaching Characteristics of Phenyl-?carbon 14|- CGA136872 Aged in Soil: Study No. HLA 6015-362. Unpublished study prepared 

by Hazleton Laboratories America, Inc. 77 p. 

40856514 2072358 Rhoads, W. (1988) Determination of the Aged Leaching Characteris- tics of 

CGA-136872 Using Pyrimidine ?carbon 14|-Labeled CGA- 136872: Study 

No. 1065. Unpublished study prepared by Colorado Analytical Research and 

Development Corp. 69 p. 

41869302 2072372 Spare, W. (1991) Leaching Characteristics of Aged ?Pyrimidinyl- carbon 14|-

CGA-136872: Lab Project Numbers: 12189; 40-90. Un- published study 

prepared by Agrisearch Inc. 102 p. 

41869303 2072373 Spare, W. (1991) Leaching Characteristics of Aged ?Pyrimidinyl- carbon 14|-

CGA-136872: Lab Project Numbers: 12188; 39-90. Un- published study 

prepared by Agrisearch Inc. 104 p. 

41869304 2072371

2072374

Spare, W. (1990) Adsorption/Desorption of ?Carbon 14|-CGA-136872: Lab 

Project Numbers: 12182; 38-90. Unpublished study prepared by Agrisearch 

Inc. 56 p. 

41869305 2072375 Spare, W. (1990) Adsorption/Desorption of ?Carbon 14|-CGA-120844: Lab 

Project Numbers: 12184; 36-90. Unpublished study prepared by Agrisearch 

Inc. 52 p. 

41869306 2072323= 

summary

Spare, W. (1990) Adsorption/Desorption of ?Carbon 14|-CGA-171683: Lab 

Project Numbers: 12183; 37-90. Unpublished study prepared by Agrisearch 

Inc. 52 p. 

41869307 2072376 Spare, W. (1990) Adsorption/Desorption of ?Carbon 14|-CGA-177288: Lab 

Project Numbers: 35-90; 12185. Unpublished study prepared by Agrisearch 

Inc. 68 p. 
37

41869308 2072377 Spare, W. (1991) Adsorption/Desorption of ?Carbon 14|-CGA-191429: Lab 

Project Numbers: 12186; 34-90. Unpublished study prepared by Agrisearch 

Inc. 64 p. 

41869309 2072378 Spare, W. (1990) Adsorption/Desorption of ?Carbon 14|-CGA-27913: Lab 

Project Numbers: 12187; 33-90. Unpublished study prepared by Agrisearch 

Inc. 52 p. 

41418620 2072365 Olson, G.; Jensen, M.; Lawrence, L. (1990) Leaching of ?Carbon 14| CGA136872 under Actual Field Conditions: Lab Project Number: 1203: 249. 

Unpublished study prepared by Pharmacology & Toxico- logy Research 

Laboratory. 293 p. 

41418621 2072359 Lawrence, L. (1988) Supplement to Mobility and Dissipation of ?Car- bon 14| 

CGA-136872 and Major Degradation Products, ?Carbon 14| CGA-120844 

and ?Carbon 14| CGA-171683, under Actual Field Condi- tions: Lab Project 

Number: 210. Unpublished study prepared by Pharmacology & Toxicology 

Research Laboratory. 5 p. 

164-1 Terrestrial field dissipation

MRID Citation Reference

40512015 2072333

2072334

Selman, F. (1987) Field Dissipation Study on CGA-136872 For Terrestrial 

Uses on Corn, Missouri: Laboratory Study No. 37402. Unpublished study 

prepared by Analytical Bio-Chemistry Laboratories, Inc. 92 p. 

40512016 2072335

2072336

Selman F. (1987) Field Dissipation Study on CGA-136872 For Terrestrial 

Uses on Corn, Georgia: Laboratory Study No. 34703. Unpublished study 

prepared by Analytical Bio-Chemistry Laboratories, Inc. 89 p. 

40512017 2072337

2072338

Van Geluwe-Barvir, K.; Ross, J. (1987) CGA-136872--Terrestrial Field 

Dissipation Study: York County, Nebraska: Laboratory Project ID ABR87119. Unpublished study prepared by Ciba-Geigy Corporation. 70 p. 

40512018 2072339

2072340

Van Geluwe-Barvir, K.; Ross, J. (1987) CGA-136872--Terrestrial Field 

Dissipation Study: Washington County, Mississippi: Laboratory Project ID 

ABR-87117. Unpublished study performed by Ciba-Geigy Corporation. 68 p. 

40512019 2072341

2072342

Van Geluwe-Barvir, K.; Ross, J. (1987) CGa-136872--Terrestrial Field 

Dissipation Study: Columbia County, New York: Laboratory Project ID ABR87120. Unpublished study performed by Ciba-Geigy Corporation. 131 p. 

40512020 2072337

2072338

National Oceanic and Atmospheric Administration (1986) Climatological

Data: Nebraska, East Central Division York AP Station ... Unpublished study. 

91 p.

40512021 DER not 

located

National Oceanic and Atmospheric Administration (1986) Climatological Data 

: Lower Delta Division: Stoneville Experiment Station ... Unpublished study . 

32 p.

40856515 2072359 Lawrence, L. (1988) Mobility and Dissipation of ?carbon 14|-CGA- 136872 

and Major Degradation Products, ?carbon 14|-CGA-120844 and ?carbon 14|-

CGA-171683, Under Actual Field Conditions: Study No. 210. Unpublished 

study prepared by Pharmacology & Toxicolo- gy Research Laboratory. 159 p. 
38

41418615 2072333 Selman, F. (1987) Supplemental Field Dissipation Study on CGA- 136872 for 

Terrestrial Uses on Corn, Missouri. Unpublished study prepared by CibaGeigy Corp. 40 p. 

41418616 2072335 Selman, F. (1987) Supplement to Field Dissipation Study on CGA-136- 872 

for Terrestrial Uses on Corn, Georgia. Unpublished study prepared by CibaGeigy Corp. 51 p. 

41418617 2072325= 

summary

Ross, J.; Van Geluwe-Barvir, K. (1987) Supplement to CGA-136872 

Terrestrial Field Dissipation Study, York County, Nebraska. Un- published 

study prepared by Ciba-Geigy Corp. 19 p. 

41418618 2072339 Van Geluwe-Barvir, K.; Ross, J. (1987) Supplement to CGA-136872 

Terrestrial Field Dissipation Study, Washington County, Missi- ssippi. 

Unpublished study prepared by Ciba-Geigy Corp. 18 p. 

41418619 2072341 Van Geluwe-Barvir, K.; Ross, J. (1987) Supplement to CGA-136872 

Terrestrial Field Dissipation Study, Columbia County, New York. Unpublished 

study prepared by Ciba-Geigy Corp. 19 p. 

43263203 DER not 

locatedSummary

Balu, K. (1994) Summary of the Terrestrial Field Dissipation Data for 

Primisulfuron-Methyl (Beacon): Lab Project Number: ABR-93056: 161940. 

Unpublished study prepared by Ciba-Geigy Corp. 69 p. 

43263204 DER not 

located

Schofield, C. (1992) Soil Dissipation study with Beacon (Primisulfuronmethyl) on Soil Planted to Sweet Corn: Final Report: Lab Project Number: 

263-89. Unpublished study prepared by Stewart Agricultural Research 

Services, Inc.; Minnesota Valley Testing Labs, Inc. 238 p. 

43263205 DER not 

located

Schofield, C. (1992) Soil Dissipation Study with Beacon (Primisulfuronmethyl) on Bare Ground: Final Report: Lab Project Number: 256-891. 

Unpublished study prepared by Stewart Agricultural Research Services, Inc.; 

Minnesota Valley Testing Labs, Inc. 236 p. 

43263206 DER not 

located

Lawrence, L. (1994) Leaching of (carbon 14)CGA-136872 Under Actual Field 

Conditions--Characterizations, Identification and Quantitation of Degradates: 

Addendum: Lab Project Number: 249. Unpublished study prepared by PTRL 

East, Inc. 155 p. 

164-2 Aquatic field dissipation

MRID Citation Reference

165-1 Confined rotational crop

MRID Citation Reference

40331268 2072332

2072312

=study report 

Madrid, S. (1987) CGA-136872--Confined Accumulation Study on Rota- tion 

Crops--Uptake of Phenyl-[Carbon 14]-CGA-136872 from a New York Field 

Plot: Laboratory Study No. ABR-87049. Unpublished study prepared by Ciba-
39

Geigy Corp. 66 p. 

40321226 2072332 Madrid, S.O. 1986 Distribution and Characterization of Phenyl-[Carbon 14]-

CGA-136872 in corn........

40856422 2072350 Madrid, S. (1988) CGA-136872--Confined Accumulation Study on Rotation 

Crops--Uptake of Pyrimidinyl-?Carbon 14|-CGA-136872 from a New York 

Field Plot: Laboratory Study No. ABR-88058. Unpublished study prepared by 

Ciba-Geigy Corp. 41 p. 

165-5

2072317= 

study reportnot a DER

Bioconcentration in Fish

166-1 Groundwater Monitoring

41804101 2072322 Blasland & Bouck, Eng. (1991) A Small-Scale Prospective Groundwater 

Monitoring Study for Primisulfuron-Methyl (Beacon): Part A: Investigation to 

Select a ... Site; Protocol No. 17-91/A: Lab Project Number: 365.18. 

Unpublished study. 174 p.

42654101 2072322 Hatfield, M.; Hiscock, A. (1993) A Small-scale Prospective Ground-water 

Monitoring Study for Primisulfuron-Methyl (Beacon) (CGA-136872): Site 

Assessment Report: Lab Project Number: 17-91 PART B: 365.18 PART B: 

CIG-NC-010-2. Unpublished study prepared by Blasland & Bouck. 21 p.

42128701 2072322= 

summary

Hatfield, M.; Masters, T. (1991) A Small-Scale Prospective Ground- Water 

Monitering Study for Primisulfuron-Methyl (Beacon): Lab Project Number: 

365.18. Unpublished study prepared by Blasland and Bouck Engineers and 

Alta Analytical Labs. 55 p. 

42040101 2072322 Selman, F. (1991) Responses to the EPA Review of Ciba-Geigy Protoc- ol 

No. 17-91 for Small-Scale Prospective Ground-Water Monitering Study for 

Primisulfuron-Methyl (Beacon): Lab Project Number: ABR-91068. 

Unpublished study prepared by Ciba-Geigy. 80 p. 

42285201 2072322 Hatfield, M. (1992) A Small-scale Prospective Groundwater Monitoring Study 

for Primusulfuron-Methyl (Beacon) (CGA-136872): Lab Project Number: 17-

91 B: Unpublished study prepared by Blasland & Bouck, Egn. and Alta 

Analytical Labs. 28 p. 

42407301 2072322 Hatfield, M. (1992) A Small-Scale Prospective Ground-Water Monitoring 

Study for Primisulfuron-methyl (Beacon) (CGA-136872): Third Progress 

Report: Lab Project Number: 17-91 B: 11092793 A. Unpublished study 

prepared by Blasland & Bouck, Egn., PC in assoc. with Alta Analytical Labs. 

38 p. 

41418622 2072366 Chang, H.; Bicking, M. (1990) Assessment of CGA-136872 75WG Leach- ing

Potential Small Scale Prospective Groundwater Monitoring Study (Beacon 

Study): Lab Project Number: TCT 4/88-CGA.1: TCT 9/ 89-CGA.1: TX-88-
40

2223. Unpublished study prepared by Twin City Testing Corp. 454 p. 

42585002 2072322 Bethem, R.; Cornacchia, J. (1992) Prospective Ground Water Monitoring 

Study for Primisulfuron-Methyl (Beacon): Fourth Progress Report: Lab 

Project Number: CIGNC01C-2: 17-91 PART C. Unpublished study prepared 

by Alta Analytical Laboratory. 287 p. 

Also a letter from K.S. Stumpf is included in this DER

201-1 Droplet size spectrum

MRID Citation Reference

41657902 2072367

2072368

Bookbinder, M. (1990) Droplet Size Spectrum of Beacon 75 WG Herbicide Sprays--Results of Wind Tunnel Testing of Aerial and Air- blast 

Application Nozzles: Lab Project Number: 31889. Unpub- lished study 

prepared by Orius Associates Inc., in association with New Mexico State 

Univ. 126 p. 

43766502 DER not 

located

Hewitt, A. (1995) Spray Drift Task Force: Atomization Droplet Size 

Spectra for Selective Active Ingredients: Lab Project Number: A92/004. 

Unpublished study prepared by SpraySearch- Daratech Pty. Ltd. and 

Spray Drift Task Force. 175 p. 

40331226-A 2072350 Huber, M. (1987) CGA-136872--Nature of the Residue in Corn--Metabolism: Laboratory Project ID: ABR-87082. Unpublished compilation 

prepared by Ciba-Geigy Corp. 151 p.

202-1 Drift field evaluation

MRID Citation Reference

41657903 2072367

2072369

Bookbinder, M. (1990) Field Spray Drift Evaluation of CGA-136872: 

(Beacon 75 WG Primisulfuron-Methyl Herbicide) Applied to Corn By Aerial 

Equipment in Pennsylvania, 1989: Lab Project Number: 32089. 

Unpublished study prepared by Orius Associates Inc., and Others. 222 p. 

41657904 2072367

2072370

Bookbinder, M. (1990) Field Spray Drift Evaluation of CGA-136872: 

Beacon 75 WG Primisulfuron-Methyl Herbicide) Applied to Corn by Aerial 

Equipment in Illinois, 1989: Lab Project Number: 31989. Unpublished 

study prepared by Orius Associates Inc., and Others 202 p. 

No MRID 2072320 Protocol Review for spraydrift evaluation

Non Guideline Selections
41

40512012 DER not 

located

Balu, K. (1988) Support Document on the Groundwater Assessment of 

CGA-136872. Unpublished study prepared by Ciba-Geigy Corporation. 42 

p. 

40856416 DER not 

located

Williams, L. (1988) CGA-136872--Storage Stability in Soil Stability of 

Residues under Freezer Storage Conditions for Two Years: Laboratory 

Project ID ABR-88096. Unpublished study prepared by Ciba-Geigy Corp. 

25 p. 

40856418 DER not 

located

Williams, R. (1987) Analytical Method for the Determination of CGA171683 in Soil by Gas Chromatography: Laboratory Project ID AG-521. 

Unpublished study prepared by Ciba-Geigy Corp. 26 p. 

41418610 2072326

2072322

Nixon, W. (1990) Response to EPA Review Dated 12/21/89 of Environmental Fate Studies Submitted to Support the Registration of Beacon 

Herbicide: Lab Project Number: ABR-90020. Unpublished study prepared 

by Ciba-Geigy Corp. 122 p. - Repeated under numerous Guidelines

41835701 DER not 

located

Bicking, M. (1991) Assessment of CGA-136872 75WG Leaching Potential 

Small Scale Prospective Groundwater monitoring Study: Final Re- port 

Addendum: Lab Project Number: 4/88-CGA.1: 9/89-CGA.1: TCT-003-88-

CGA.1-BEA. Unpublished study prepared by Twin City Testing Corp. 19 p. 

42585001 2072322 Hatfield, M.; Hiscock, A. (1992) A Small-scale Prospective Ground-water 

Monitoring Study for Primisulfuron-Methyl (Beacon) (CGA-136872): 

Interim Report: Lab Project Number: 365.18 PART B: CIG-NC-010-2: 17-

91 PART B. Unpublished study prepared by Blasland & Bouck Engineers, 

P.C. and Alta Analytical Laboratory. 120 p. 

42654100 ReportDER not 

located

Ciba-Geigy (1993) Submission of environmental fate data (investiga- tion 

of vandalism at groundwater study site) for registration of Beacon 

Herbicide. Transmittal of 1 study. 

42654101 2072322 Hatfield, M.; Hiscock, A. (1993) A Small-scale Prospective Ground-water 

Monitoring Study for Primisulfuron-Methyl (Beacon) (CGA-136872): Site 

Assessment Report: Lab Project Number: 17-91 PART B: 365.18 PART 

B: CIG-NC-010-2. Unpublished study prepared by Blasland & Bouck. 21 

p. 

43263207 DER not 

locatedRegistrant 

modeling

Coody, P. (1994) Prediction of CGA-136872 Dissipation and Leaching 

Using PRZM: Comparison to Lysimeter and Ground Water study Results: 

Lab Project Number: 833. Unpublished study prepared by PTRL East, Inc. 

62 p. 

43263208 Registrant 

responseDER not 

located

Balu, K. (1994) Response to EPA'S 11/93 Review of Progress Reports 

Submitted in Connection with the Small-Scale Prospective Ground-Water 

Monitoring Study of Beacon Herbicide in Indiana: Lab Project Number: 

ARB-94016: 161940. Unpublished study prepared by Ciba-Geigy Corp. 52 

p. 

43263209 DER not 

located

Hiscock, A. (1994) A Small-Scale Prospective Ground-Water Monitoring 

Study for Primisulfuron-methyl (Beacon) (CCGA-136872): Amended Final 

Report: Lab Project Number: 17-91: 365.18: CIGNCOIC-2. Unpublished 

study prepared by Ciba-Geigy Corp.; Blasland & Bouck Engineers, P.C.; 

A&L Midwest Labs; Alta Analytical Lab, Inc.; Enseco-Rmal Lab. 731 p. 

43263210 Registrant Williams, W.; Cheplick, J. (1994) PRZM-2 Simulations of Primisulfuron-
42

modeling 

exercise

methyl (Beacon) in LaGrange County, Indiana: Final Report: Lab Project 

Number: 242.11: 221-94. Unpublished study prepared by Waterborne 

Environmental, Inc. 53 p. 

43263211 DER not 

locatedRegistrant 

assessment

Williams, W.; Hahn, A. (1992) The Potential for Primisulfuron-Methyl 

(Beacon) to Leach to Ground Water in New York State: Final Report: Lab 

Project Number: 92AG013. Unpublished study prepared by Clendenin 

Consulting & Remediation Group. 79 p. 

42040102 2072322 Bethem, R. (1991) Determination of Primisulfuron-methyl and Its 

Metabolites in Water and Soil by High Performance Liquid 

Chroma- tography/Mass Spectrometry: Lab Project Number: 

CIGNCO1C-3. Un- published study prepared by Alta Analytical 

Lab. 73 p. 

40512019 B 2072343

2072344 Analytical methods used in field dissipation study

40512019-C 2072345

2072346 Storage Stability for Field dissipation study

41869301 2072371 to

2072377

Phelps, W. (1991) Summary of Additional Environmental Fate Studies 

Required by EPA on CGA-136872 (Primisulfuron-methyl): Lab Pro- ject 

No: ABR-91029. Unpublished study prepared by Ciba-Geigy Corp. 15 p. 

Submitted Effects Studies

71-1 Avian Single Dose Oral Toxicity

MRID Citation Reference

40331250 2072382 Fletcher, D. (1985) Acute Oral Toxicity Study with CGA-136872 Technical in Bobwhite Quail: [Final Report]: Laboratory Study No. 85 QD 55. 

Unpublished study prepared by Bio-Life Associates, Ltd. 32 p. 

40331251 2072383 Fletcher, D. (1985) Acute Oral Toxicity Study with CGA-136872 Technical in Mallard Ducks: [Final Report]: Laboratory Study BLAL No. 85 DD 

31. Unpublished study prepared by Bio-Life Associ- ates, Ltd. 32 p. 

71-2 Avian Dietary Toxicity

MRID Citation Reference

40331252 2072384 Fletcher, D. (1985) 8-day Dietary LC50 Study with CGA-136872 Technical in Mallard Ducklings: Laboratory Study BLAL No. 85 DC 55. 

Unpublished study prepared by Bio-Life Associates, Ltd. 44 p. 

40331253 2072385 Fletcher, D. (1985) 8-day Dietary LC50 Study with CGA-136872 Technical in Bobwhite Quail: Laboratory Study BLAL No. 85 QC 54. 

Unpublished study prepared by Bio-Life Associates, Ltd. 44 p. 
43

71-4 Avian Reproduction

MRID Citation Reference

40512003 2072392 Fletcher, D. (1987) Toxicity and Reproduction Study with CGA-136872 

Technical in bobwhite Quail: Laboratory Study No. 86 QR 18. Unpublished 

study prepared by Bio-Life Associates, Ltd. 214 p. 

40512004 2072393 Fletcher, D. (1987) Toxicity and Reproduction Study with CGA-136872 

Technical in Mallard Ducks: Laboratory Project ID 86 DR 17. Unpublished 

study prepared by Bio-Life Associates, Ltd. 199 p. 

41418602 See 

2072417 

memo

Fletcher, D. (1987) Supplemental to Toxicity and Reproduction Study with 

CGA-136872 Technical in Bobwhite Quail: Lab Project Number: 81QR2: 

81QR3: 81QR5. Unpublished study prepared by Bio-Life Associates, Ltd. 

25 p. 

72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

40331254 2072386 Surprenant, D. (1986) Acute Toxicity of CGA-136872 to Rainbow Trout 

(Salmo gairdneri): Laboratory Study No. BW-86-2-1946. Unpub- lished 

study prepared by Springborn Bionomics, Inc. 23 p. 

40331255 2072387 Surprenant, D. (1986) Acute Toxicity of CGA-136872 to Bluegill (Lepomis 

macrochirus): Laboratory Study No. BW-86-2-1944. Un- published study 

prepared by Springborn Bionomics, Inc. 24 p. 

41418603 2072403 Lelievre, M. (1990) Acute Toxicity to Bluegill Sunfish (Lepomis macrochirus) under Static Conditions: CGA-136872 Amended Final Report: 

Lab Project Number: 90-1-3186. Unpublished study pre- pared by 

Springborn laboratories, Inc. 42 p. 

41418604 2072404 Lelievre, M. (1990) Acute Toxicity to Rainbow Trout (Oncorhyncus mykiss) 

under Static Conditions: CGA-136872: Lab Project Number: 90-2-3238: 

1781.1189.6223.103. Unpublished study prepared by Springborn 

Laboratories, Inc. 41 p. 

41781501 2072408 Lelievre, M. (1991) Acute Toxicity to Bluegill Sunfish (Lepomis -

Macrochirus) Under Static Conditions: CGA-136872: Lab Project Number: 

91-1-3632. Unpublished study prepared by Springborn Laboratories, Inc. 

51 p. 

41781502 2072409 Lelievre, M. (1991) Acute Toxicity to Rainbow Trout (Oncorhynchus 

Mykiss) Under Static Conditions: CGA-136872: Lab Project Number: 91-1-

3643. Unpublished study prepared by Springborn Labora- tories, Inc. 55 p. 
44

72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

40331256 2072388 Surprenant, D. (1986) Acute Toxicity of CGA-136872 to Daphnids 

(Daphnia magna): Laboratory Study No. BW-86-2-1949. Unpublished 

study prepared by Springborn Bionomics, Inc. 23 p. 

41418605 2072405 Lelievre, M. (1990) Acute Toxicity Test to Daphnids (Daphnia magna) 

under Static Conditions: CGA-136872 Amended Final Report: Lab Project 

Number: 90-1-3185: 1781.1189.6225.110. Unpublished stu- dy prepared 

by Springborn Laboratories, Inc. 45 p. 

72-3 Acute Toxicity to Estuarine/Marine Organisms

MRID Citation Reference

40331257 2072389 Surprenant, D. (1986) Acute Toxicity of CGA-136872 to Sheepshead 

Minnow (Cyrinodon variegatus): Laboratory Study No. BW-86-2- 1947. 

Unpublished study prepared by Springborn Bionomics, Inc. 24 p. 

40331258 2072390 Surprenant, D. (1987) Acute Toxicity of CGA-136872 to Embryos-lar- vae 

of the Quahog Clam (Mercenaria mercenaria): Laboratory Study No. BW87-5-2371. Unpublished study prepared by Springborn Bio- nomics, Inc. 

26 p. 

40331259 2072391 Surprenant, D. (1986) Acute Toxicity of CGA-136872 to Mysid Shrimp 

(Mysidopsis bahia): Laboratory Study No. BW-86-2-1950. Unpub- lished 

study prepared by Springborn Bionomics, Inc. 24 p. 

41364001 Supplement 

to 

40331258

Surprenant, D. (1990) Supplement to Acute Toxicity of CGA-136872 to 

Embryos-larvae of the Quahog Clam (Mercenaria mercenaria): Study No. 

1781.0187.6134.514. Unpublished compilation prepared by Ciba-Geigy 

Corp., Agricultural Div. and Springborn Labora- tories, Inc. 10 p. 

41418606 2072406 Lelievre, M. (1990) Acute Toxicity to Sheepshed Minnow (Cyprinodon 

variegatus) under Static Conditions: CGA-136872 Amended Final Report: 

Lab Project Number: 90-1-3187: 1781.1189.6220.500. Un- published 

study prepared by Springborn Laboratories, Inc. 43 p. 

41418607 2072407 Lelievre, M. (1990) Acute Toxicity to Mysid Shrimp (Mysidopsis bahia) 

under Static Conditions: CGA-136872: Final Report: Lab Project No. 90-

3-3256: 1781.1189.6221.510. Unpublished study prepared by Springborn 

Laboratories, Inc. 38 p. 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference

40512005 2072394 Sugatt, R. (1987) Early Life Stage Test of CGA-136872 with Fathead 
45

Minnows (pimephales promelas): Laboratory Study No. 1086. 

Unpublished study performed by Envirosystems, Inc. 68 p. 

40512006 2072395 Sugatt, R. (1987) Chronic Toxicity Test of CGA-136872 with Daphnia 

Magna: Laboratory Study No. CGA-DM-2051-A. Unpublished study 

prepared by Envirosystems, Inc. 55 p. 

41418608 DER not 

locatedreferenced in 

2072419 as 

supplemental

Ward, T.; Boeri, R. (1990) Early Life-Stage Toxicity of CGA-136872 to 

the Fathead Minnow, Pimephales Promelas: Lab Project Number: 8917-

CG. Unpublished study prepared by EnviroSystems Division/ Resource 

Analysts, Inc. 32 p. 

41418609 DER not 

locatedreferenced in 

2072435 as 

Core

Boeri, R.; Ward, T. (1990) Chronic Toxicity of CGA-136872 to the 

Daphnid, Daphnia magna: Lab Project Number: 8918-CG. Unpub- lished 

study prepared by EnviroSystems Div./Resource Analysts, Inc. 34 p. 

122-1 Seed Germination/Seedline Emergence and Vegetable Vigor

MRID Citation Reference

40512010 2072396 Canez, V. (1987) Nontarget Phytotoxicity Study: Vegetative Vigor Tier 1: 

Laboratory Study No. PAL 23-TX0451. Unpublished study prepared by 

Pan Agricultural Labs, Inc. 39 p. 

40512011 2072397 Canez, V. (1987) CGA-136872: Nontarget Phytotoxicity Study: Seed 

Germination/Seedling Emergence Tier 1: Laboratory Study No. PAL 23-

TX0449. Unpublished study prepared by Pan Agricultural Labs, Inc. 55 p. 

123-1 Seed germination/seedling emergence and vegitative vigor

MRID Citation Reference

40856505 2072400 Canez, V. (1988) Nontarget Phytotoxicity Test Seed Germination/-

Seedling Emergence Tier 2: CGA-136872: Study No. LR87-34B. Unpublished study prepared by Pan-Agricultural Laboratories, Inc. 269 p. 

40856506 2072401 Canez, V. (1988) Nontarget Phytotoxicity Test Vegetative Vigor Tier 2: 

CGA-136872: Study No. LR87-34A. Unpublished study prepared by PanAgricultural Laboratories, Inc. 207 p. 

123-2 Aquatic plant growth
46

MRID Citation Reference

40520101 2072398 Hughes, J. (1986) The Toxicity of CGA-136872, Lot No.... to Selenastrum 

capricornutum: Laboratory Project ID 0267-31-1100-1. Unpublished study 

prepared by Malcolm Pirnie, Inc. 32 p. 

40520102 2072399 Hughes, J. (1987) The Toxicity of CGA-136872, Lot No... to Lemna gibba: 

Laboratory Project ID 0267-31-1100-2. Unpublished study prepared by 

Malcolm Pirnie, Inc. 30 p. 

42147901 2072410 Hughes, J. (1989) The Toxicity of CGA-136872 Technical to Seletonema 

costatum: Lab Project Number: T1P909002. Unpublished study prepared 

by Ciba-Geigy Corp. 36 p. 

42147902 2072411 Hughes, J. (1989) The Toxicity of CGA-136872 Technical to Anaebaena 

flos-aquae: Lab Project Number: 0267-46-1100-1. Unpublished study 

prepared by Malcolm Pirnie, Inc. 36 p. 

42147903 2072412 Hughes, J. (1989) The Toxicity of CGA-136872 Technical to Navicula 

pelliculosa: Lab Project Number: 0267-46-1100-2. Unpublished study 

prepared by Ciba-Geigy Corp. 34 p. 

141-1 Honey bee acute contact

MRID Citation Reference

41364002 2072402 Hoxter, K. (1989) CGA-136872 Technical: An Acute Toxicity Study with 

the Honeybee: Lab Study No. 108-306. Unpublished study prepared by 

Wildlife International Ltd. 14 p. 
47

Appendix A. Justification for Special Study

Guideline Number: none

Study Titles: Special Study for Non-Target Plant Reproductive Toxicity

Rationale for Requiring the Data

As stated in the Problem Formulation, investigations/studies have indicated a small percentage of the 

label application rate of low dose high potency herbicides such as sulfonylureas (e.g. primisulfuron) may 

impact the reproduction of non-target terrestrial plants. However, there are no available data on adverse 

reproductive impacts to terrestrial plants from primisulfuron residues due to spray drift. Terrestrial plant 

reproductive toxicity data would help to screen for potential plant risks associated with primisulfuron use. 

Plants form the basis of most habitats and contribute significantly to overall environmental quality. The 

loss of plant reproductive output could potentially have an adverse effect on animals, both invertebrates 

and vertebrates, as many are dependent on plant reproduction for a food source and for habitat quality 

and structure. A solid understanding of the potential risks to plants is therefore essential for sound 

environmental management. A study protocol must be submitted for review and approved by the Agency 

prior to initiation of the study.

Practical Utility of the Data

How will the data be used? 

The data will be used to estimate potential reproductive risks to non-target terrestrial plants, including the 

likelihood of potential risks to endangered species, either by direct effects or by indirect effects, and to 

reduce uncertainties associated with the current ecological risk assessment. By refining the assessment, 

the Agency will be able to determine whether current labeling is appropriate and whether further 

mitigation is necessary. In the absence of this data, risks to terrestrial plants will be presumed.

How could the data impact the Agency’s future decision-making?

These data, once submitted, should allow the Agency to characterize the risk posed to plant reproductive 

processes from primisulfuron in terrestrial ecosystems. Primary producers (i.e. plants) provide food and 

habitat vital to ecological processes. Therefore, a solid understanding of the potential risks to non-target 

plants is essential in order to assess the environmental risks the use of primisulfuron may pose. If the 

data indicate that primisulfuron poses significant risks to these non-target plant species, the Agency may 

explore additional decision options to minimize the risks to these species. The lack of these data will 

limit the flexibility the Agency and registrants have in complying with the Endangered Species Act and 

could result in use restrictions for primisulfuron which may otherwise be avoided, or which are 

unnecessarily severe. 
48

Appendix B. Proposed Metabolic Pathway
49

Appendix C. Incident Reports

EIIS Pesticide Summary Report: General Information

Primisulfuron-methyl (128973)

Incident # Date County State Certainty Legal. Formul. Appl. Method Total Magnitude

PLANTS

Agricultural area

I009550-001 11/15/1999 NE 3 RU N/R N/R UNKNOWN

I013554-053 6/26/2002 Ford KS 3 UN DF Broadcast 65 acres

Corn

I014597-036 Dunn ND 2 RU WDG Spray 150 acres

I007796-009 7/1/1997 BROWN SD 3 RU DF Spray 180 ACRES

I009573-023 6/16/1999 KNOX IN 3 RU DF Broadcast ALL

I009573-038 6/16/1999 SEWARD KS 3 RU DF Broadcast 40 ACRES

I009573-030 6/22/1999 IDA IA 3 MA DF Broadcast 80 ACRES

I009573-037 6/22/1999 UNION KY 3 RU DF Broadcast ALL

I009573-029 6/22/1999 BUENA VISTA IA 3 MA DF Broadcast 10 ACRES

I009573-022 6/22/1999 KNOX IN 3 RU DF N/R ALL

I009573-017 7/1/1999 GRANT WI 3 MA DF Spray 49% OF 135 ACRES

I009573-012 7/1/1999 GRUNDY IA 3 MA DF Broadcast 50% OF 80 ACRES

Wednesday, December 21, Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. Page 1 of 5

Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), U=Unknown.
50

Incident # Date County State Certainty Legal. Formul. Appl. Method Total Magnitude

I009573-020 7/2/1999 CALHOUN IA 3 MA DF Broadcast 50% OF 20 ACRES

I009573-021 7/26/1999 KANE IL 2 RU DF Broadcast 50% OF 39 ACRES

I016814-001 6/25/2005 Daviess IL 1 RU WDG Spray 10-30 acres of corn

Corn, field

I013554-024 7/1/2002 KEYA PAHA NE 3 M DF Broadcast 188 acres

N/R

I009573-006 7/1/1999 SCOTT IL 3 MA DF Broadcast 68% OF 110 ACRES

I010837-074 6/19/2000 MONTGOMERY IN 3 RU DF Broadcast 57%

I010837-034 6/20/2000 MOORE TX 3 UN DF AIR; BROADCAST ALL

I010837-039 6/20/2000 JACKSON IN 3 RU DF Broadcast ALL

I010837-037 6/21/2000 OCHILTREE TX 3 UN DF Broadcast ABOUT 630 

ACRES

I010837-071 6/21/2000 ADAMS NE 3 RU DF Broadcast ALL

I010837-036 6/21/2000 SHERMAN TX 3 UN DF Broadcast ALL

I010837-031 6/27/2000 DOUGLAS SD 3 RU DF Broadcast ALL

I010837-030 6/27/2000 DOUGLAS SD 3 UN DF N/R ALL

I010837-042 6/30/2000 DANE WI 3 UN DF Broadcast 1 ACRE

I010837-035 7/12/2000 OCHILTREE TX 3 UN DF Broadcast ALL

I010837-070 7/15/2000 SWIFT MN 3 UN DF N/R ALL

Wednesday, December 21, Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. Page 2 of 5

Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), U=Unknown.
51

Incident # Date County State Certainty Legal. Formul. Appl. Method Total Magnitude

I010837-068 7/26/2000 STEELE MN 3 MA DF Broadcast 80 ACRES

I013554-041 11/2/2001 Olmsted MN 3 UN DF Broadcast 40 acres

I013554-042 11/16/2001 Floyd IA 3 M DF Broadcast 110 acres

I013554-055 6/17/2002 Rawlins KS 3 UN DF Broadcast 122 acres

I013554-043 6/18/2002 Huron MI 2 UN DF Broadcast 120 acres

I013554-054 6/27/2002 Ford KS 3 UN DF Broadcast 65 acres

I013554-046 7/1/2002 Douglas SD 3 M DF Broadcast 68 acres

I013554-051 7/3/2002 Redwood MN 3 M DF Broadcast 112 acres

I013554-045 7/8/2002 Saginaw MI 3 UN DF Broadcast 36 acres

I013554-044 7/10/2002 Republic KS 3 UN DF Broadcast 40 acres

I013554-049 7/19/2002 Mower MN 3 UN DF Broadcast 30 acres

I013554-048 7/22/2002 Chippewa WI 3 M DF Broadcast 65 acres

I013554-050 7/23/2002 Monona IA 3 M DF Broadcast 480 acres

I013554-047 11/27/2002 Peoria IL 3 M DF Broadcast 160 acres

I016790-007 9/20/2005 Cortland NY 2 UN SC Spray Unknown

Soybean

I010837-003 12/7/1999 FLOYD TX 3 RU DF GROUND ALL

I010837-046 5/24/2000 MC PHERSON KS 3 UN DF BAND 585 ACRES

I010837-060 6/6/2000 MONROE MO 3 RU DF Broadcast 160 ACRES

I010837-057 6/9/2000 WABAUNSEE KS 3 RU DF Broadcast ALL

Wednesday, December 21, Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. Page 3 of 5

Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), U=Unknown.
52

Incident # Date County State Certainty Legal. Formul. Appl. Method Total Magnitude

I010837-041 6/14/2000 SCOTT IL 3 RU DF Broadcast ALL

I010837-052 6/14/2000 RICE KS 3 UN DF Broadcast ALL

I010837-025 6/19/2000 PIKE IL 3 RU DF Broadcast ALL

I010837-053 6/20/2000 SCOTT IL 3 RU DF Broadcast 60 ACRES

I010837-027 6/21/2000 MONTGOMERY IN 3 RU DF Broadcast ABOUT 4000 

ACRES

I010837-022 6/23/2000 MACOUPIN IL 3 RU DF BAND ABOUT 80 ACRES

I010837-049 6/29/2000 WOODSON KS 3 RU DF Broadcast ALL

I010837-065 7/5/2000 EDWARDS KS 3 RU DF Broadcast ALL

I010837-064 7/5/2000 HENRY IL 3 UN DF Broadcast ALL

I010837-023 7/6/2000 KNOX NE 3 MA DF Broadcast ABOUT 20 ACRES

I010837-038 7/6/2000 MONTGOMERY IN 3 RU DF Broadcast APPROX. 700 

ACRES

I010837-054 7/7/2000 RICE KS 3 RU DF Broadcast ALL

I010837-056 7/10/2000 TIPPECANOE IN 3 RU DF Broadcast 65 ACRES OUT OF 

75

I010837-028 7/11/2000 SPENCER IN 3 RU DF Broadcast ABOUT 64 ACRES

I010837-026 7/11/2000 PIKE IL 3 RU DF Broadcast ALL

I010837-047 7/28/2000 YELLOW MEDICINE MN 3 RU DF Broadcast ALL

I014597-044 5/22/2003 Franklin KS 3 M WDG Spray 50 acres

Wednesday, December 21, Certainty Code: 0=Unrelated, 1=Unlikely, 2=Possible, 3=Probable, 4=Highly Probable. Page 4 of 5

Legality Code: RU=Registered Use, M=Misuse, MA=Misuse (Accidental), MI=Misuse (Intentional), U=Unknown.
53

Incident # Date County State Certainty Legal. Formul. Appl. Method Total Magnitude

Soybeans

I014597-035 5/26/2003 Van Buren MI 3 M WDG Spray 300 acres

Sugar beet

I007796-001 8/21/1998 LAKE MI 2 UN N/R ALL 70 ACRES

Sugar beets

I014597-037 4/18/2003 Huron MI 3 M WDG Spray 43 acres
54

Appendix D. Degradate Toxicity Comparison 

The following analysis has been conducted to determine the value of further laboratory toxicity 

data on the primisulfuron-methyl degradate CGA171683, or 2-amino-4,6-

bis(difluoromethoxy)pyrimidine. The approach used combines quantitative structure-activity 

relationship (QSAR) analysis (ECOSAR model v1.00) with toxicity information from a 

surrogate chemical. A screening-level total toxic residue (TTR) aquatic exposure analysis 

(GENEEC 2.0) was then conducted, to determine if exposures were in the range where effects 

due to CGA171683 were expected, based on the estimated toxicity. These results were 

compared to determine if it is likely that exposure to CGA171683 will approach levels of 

concern (LOC).

It is concluded that exposures to parent plus CGA171683 are nearly two orders of magnitude 

below the lowest effects level and thus it is unlikely that aquatic EEC from applications of 

primsulfuron methyl will reach levels triggering LOCs, based on predicted toxicity. The value of 

further laboratory toxicity data on aquatic organisms is therefore low. For the purposes of risk 

assessment the TTR exposure approach will be used to assess risk from applications of 

primsulfuron methyl in lieu of additional toxicity data for CGA 171683. The following sections 

describe this analysis in more detail.

No toxicity data is available for CGA171683. However, the FOOTPRINT database 

http://sitem.herts.ac.uk/aeru/footprint/en/index.htm) gives toxicity endpoints for the nonfluorinated analog AEF092944 (INJV0290), which is a degradate of numerous other 

sulfonylurea herbicides, including bensulfuron, foramsulfuron, and mesosulfuron. Table D1 

presents the aquatic toxicity data given in FOOTPRINT for the analog. Note that EPA has not 

reviewed the data in FOOTPRINT for validity and thus there is some uncertainty associated with 

this analysis. Acute toxicity endpoints for the analog place it in the slightly toxic (LC50 10-100 

ppm) to practically non-toxic (LC50 > 100 ppm) categories. The structures of both chemicals 

are given in Table D3.

Surrogate Toxicity Data

The structures of CGA171683 and its analog (AEF092944) were entered into the ECOSAR v.1.0 

model as SMILES strings. The results are shown below. The analog was classified by ECOSAR 

as a neutral organic chemical (baseline toxicity model) and as an aniline (aromatic amine). 

CGA171683 was classified as a neutral organic, an aromatic amine, and as a halo ether. 

Predicted endpoints for the analog were compared to the endpoints given in FOOTPRINT. 

Table D1 shows the best matches between reported and predicted toxicity for the analog. The 

best match for the fish acute toxicity test was given by the aromatic amine QSAR. The other 

endpoints (algae and daphnid acute and chronic) were best matched by the baseline neutral 

organic QSAR. The agreement is considered to be good, as endpoints were matched to within 

better than a factor of 5.

QSAR Analysis for Analog

Table D1. Toxicity Data for Analog Chemical And QSAR Analysis for Analog and CGA171683

endpoint INJV0290/AEF092944

(FOOTPRINT data)

INJV0290/AEF092944

(ECOSAR)

CGA171683

(ECOSAR)

Fish 96-h LC50 97 mg/L 78 mg/L (a.a.) 48.9 mg/L (a.a.)
55

(rainbow trout) 

Fish Chronic No data 0.38 mg/L (a.a.) ChV 0.17 mg/L (a.a.) ChV

Algae 72h EC50 120 mg/L 

(P. subcapitata)

131 mg/L (n.o.) 69.7 mg/L (n.o.)

Lemna 7-d EC50 > 100 mg/L No prediction No prediction

Daphnia 48-h EC50 > 100 mg/L 469 mg/L (n.o.) 185 mg/L (n.o.)

Daphnid Chronic 24 mg/L (21-d NOEC) 36 mg/L (n.o.)ChV 16 mg/L (n.o.) ChV

a.a. = aromatic amine ECOSAR class

n.o. = neutral organic ECOSAR class

ChV = ECOSAR chronic toxicity value

Table D1 also gives the predicted toxicity of CGA171683, from the same QSAR class that best 

matched the analog (aromatic amine for fish and neutral organic for daphnia and algae). For 

acute endpoints, the predictions place CGA171683 in either the slightly toxic or practically nontoxic category. Overall, the endpoints for CGA171683 are predicted to be about half of those for 

the analog (i.e., CGA171683 is predicted to be about twice as toxic).

QSAR Analysis of CGA171683

To place the toxicity predictions in context, a screening-level aquatic exposure analysis 

(GENEEC model) was performed. The GENEEC model was run with the parent stable to all 

degradation processes, to account for exposure to any degradates. This approach has been 

widely used in EFED and has been referred to as the total toxic residue (TTR) approach. Table 

D2 gives the input parameters.

Screening Exposure Analysis

Table D2. Total Toxic Residue Aquatic Exposure analysis for Primisulfuron-methyl and Degradates

Input parameter Value Reference

Maximum Application rate 0.036 lb/A Problem formulation, DP394823, 

Number of applications One (1) 01/12/12

Average Koc, mL/g o.c. 66 (avg of 74.5, 57.4, 66.3)

Solubility 70 ppm

Application type Aerial, fine spray, 24.1 % drift Conservative assumption

Degradation processes All stable Conservative assumption to 

account for any degradates

No-spray zone Zero feet Conservative assumptions

Incorporation depth Zero inches

The GENEEC run (below) returns an acute exposure of approximately 2 ppb (0.002 ppm) for all 

exposure averaging times.

The toxicity predictions for CGA171683 indicate that it is more toxic to fish than the parent 

(LC50 = 210 ppm and NOAEC = 11 ppm); less toxic to algae (parent EC50 = 0.098 ppm); about 

the same for daphnia acute toxicity (parent EC50 > 100 ppm); and less toxic to daphnia on a 

chronic basis (parent NOAEC 0.41 ppm). All parent data were taken from the Problem 

Formulation date 01/12/12, DP394823). Because the predicted toxicity of CGA171683 is near 

that of parent primisulfuron-methyl, exposures to either chemical will result in similar risk 

conclusions at a given exposure.

Interpretation
56

ECOSAR makes no prediction for aquatic vascular plants (Lemna), however the analog 

AEF092944 (EC50 > 100 ppm) is less toxic than parent primisulfuron (EC50 = 0.0008 ppm). If 

the pattern predicted by QSAR analysis holds, CGA171683 should also be less toxic than its 

parent for Lemna.

The exposure analysis indicates a maximum exposure of about 2 ppb (0.002 ppm) for TTR of 

primisulfuron-methyl. The one-year exposure for CGA171683 is expected to be lower than this. 

However, due to the high production (75%) of CGA171683 in environmental fate studies, and its 

apparent stability, there may be some accumulation above 2 ppb over time in the farm pond 

modeled by GENEEC, thus the EEC would be somewhat higher than 2 ppb.

Comparison of the predicted exposure (0.002 ppm) to the lowest toxicity endpoint predicted for 

CGA171683 (0.17 ppm ChV for chronic effects to fish) indicates that the exposure is too low to 

trigger the LOC, by almost two orders of magnitude (i.e. 85x). Even accounting for uncertainty 

in the exposure and toxicity predictions, it is considered unlikely that additional laboratory 

toxicity data for CGA171683 will change the likely risk conclusions for parent primisulfuronmethyl. The value of such data is therefore considered low, and risks from CGA171683 may be 

analyzed as part of a TTR approach using toxicity data for the parent, or QSAR estimates as 

appropriate.

The toxicity data for the analog compound, AEF092944, were retrieved from the on-line 

database FOOTPRINT. The data have not been reviewed by EPA, thus the data quality is 

unknown. The results are used as given.

Uncertainties

Uncertainties for the QSAR analyses are given in Appendix B. The warning for halogenated 

aromatic amines is not expected to apply to CGA171683, because it does not have halogen atoms 

on its aromatic ring. The predictions for the analog AEF092944 are considered to be good 

(within a factor of 5).

The exposure analysis for primisulfuron-methyl is considered to be conservative, because it does 

not account for degradation processes, thus maximizing exposure to any degradates formed by 

maximizing parent exposure. GENEEC does not account for accumulation over the 30-year 

model run in a typical PRZM-EXAMS run, however the low exposure in the one-year GENEEC 

run indicates that exposure to CGA171683 would likely also be low. This uncertainty can be 

resolved in the risk assessment using Tier 2 aquatic exposure analysis (PRZM-EXAMS).
57

Table D3. Structures of CGA171683 and its Analog, AEF092944 (INJV0290)

AEF092944

CGA171683
58

ECOSAR runs for CGA171683 and its analog (AEF092944/INJV0290)

SMILES : Nc1nc(OC(F)F)cc(OC(F)F)n1

CHEM : CGA171683 2-amino-4,6-bis(dif1uoromethoxy)pyrimidine

CAS Num: 

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C6 H5 F4 N3 O2 

MOL WT : 227.12

Log Kow: 1.67 (KowWin estimate)

Melt Pt: 

Wat Sol: 1189 mg/L (WskowWin estimate)

ECOSAR v1.00 Class(es) Found

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

Anilines (Aromatic Amines)

Halo Ethers 

 Predicted

ECOSAR Class Organism Duration End Pt mg/L (ppm)

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

Anilines (Aromatic Amines) : Fish 96-hr LC50 48.934

Anilines (Aromatic Amines) : Fish 14-day LC50 55.664

Anilines (Aromatic Amines) : Daphnid 48-hr LC50 2.505

Anilines (Aromatic Amines) : Green Algae 96-hr EC50 11.486

Anilines (Aromatic Amines) : Fish ChV 0.171

Anilines (Aromatic Amines) : Daphnid ChV 0.042

Anilines (Aromatic Amines) : Green Algae ChV 7.220

Halo Ethers : Fish 96-hr LC50 100.859

Halo Ethers : Daphnid 48-hr LC50 24.315

Halo Ethers : Fish ChV 5.406 !

Halo Ethers : Daphnid ChV 1.845 !

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

Neutral Organic SAR : Fish 96-hr LC50 334.633

(Baseline Toxicity) : Daphnid 48-hr LC50 185.480

 : Green Algae 96-hr EC50 69.758

 : Fish ChV 32.001

: Daphnid ChV 16.152

: Green Algae ChV 23.758

Note: * = asterisk designates: Chemical may not be soluble

 enough to measure this predicted effect.

Note: ! = exclamation designates: The toxicity value was determined from

 a predicted SAR using established acute-to-chronic ratios and ECOSAR

 regression techniques which are documented in the supporting Technical Reference Manual. When possible, this toxicity value should be considered in a weight of evidence approach.

Anilines (Aromatic Amines): --------------------------

 For Fish Acute Toxicity Values: 2,3,5,6-Tetrachloroaniline is 19 times

more toxic than predicted by this SAR. Tetrabromoaniline may be more toxic

than predicted by this SAR as well.

 For Daphnid and Green Algae Toxicity Values: Tetrachloro- and tetrabromaniline may be 20 times toxic than predicted by this SAR.

 N-Substituted anilines are less toxic than predicted by these SARs;

for these compounds, Neutral Organic SARs are used.

ECOSAR v1.00 SAR Limitations:
59

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

Maximum LogKow: >7.8 (Fish 96-hr LC50, Daphnid 48-h LC50)

Maximum LogKow: >3.7 (Fish 14-day LC50)

Maximum LogKow: >4 (Green Algae 96-hr EC50 and ChV)

Maximum LogKow: >4.3 (Fish ChV)

Maximum LogKow: >2.4 (Daphnid ChV)

Maximum Mol Wt: 1000

Halo Ethers :

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

 For Fish and Daphnid Acute Toxicity Values: If the log Kow of the chemical

is greater than 5.0, or if the compound is solid and the LC50 exceeds the

water solubility by 10X, no effects at saturation are predicted for these

endpoints.

 For Green Algae Acute Toxicity Values: If the log Kow of the chemical is

greater than 6.4, or if the compound is solid and the EC50 exceeds the water

solubility by 10X, no effects at saturation are predicted for these endpoints.

For All Chronic Toxicity Values: If the log Kow of the chemical is greater

than 8.0, or if the compound is solid and the ChV exceeds the water solubility

by 10X, no effects at saturation are predicted for these endpoints.

ECOSAR v1.00 SAR Limitations:

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

Maximum LogKow: 5.0 (LC50)

Maximum LogKow: 6.4 (EC50)

Maximum LogKow: 8.0 (ChV)

Maximum Mol Wt: 1000

Baseline Toxicity SAR Limitations:

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

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50)

Maximum LogKow: 6.4 (Green Algae EC50)

Maximum LogKow: 8.0 (ChV)

Maximum Mol Wt: 1000

SMILES : n1c(N)nc(OC)cc1OC

CHEM : AEF092944

CAS Num: 036315-01-2

ChemID1: 

ChemID2: 

ChemID3: 

MOL FOR: C6 H9 N3 O2 

MOL WT : 155.16

Log Kow: 0.95 (KowWin estimate)

Melt Pt: 

Wat Sol: 1.108E+004 mg/L (WskowWin estimate)

ECOSAR v1.00 Class(es) Found

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

Anilines (Aromatic Amines)

 Predicted

ECOSAR Class Organism Duration End Pt mg/L 

(ppm)

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

==========

Anilines (Aromatic Amines) : Fish 96-hr LC50 78.845

Anilines (Aromatic Amines) : Fish 14-day LC50 225.619

Anilines (Aromatic Amines) : Daphnid 48-hr LC50 2.376
60

Anilines (Aromatic Amines) : Green Algae 96-hr EC50 9.172

Anilines (Aromatic Amines) : Fish ChV 0.380

Anilines (Aromatic Amines) : Daphnid ChV 0.050

Anilines (Aromatic Amines) : Green Algae ChV 6.078

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

==========

Neutral Organic SAR : Fish 96-hr LC50 922.143

(Baseline Toxicity) : Daphnid 48-hr LC50 468.756

 : Green Algae 96-hr EC50 131.427

 : Fish ChV 89.591

 : Daphnid ChV 35.968

: Green Algae ChV 39.276

Note: * = asterisk designates: Chemical may not be soluble

 enough to measure this predicted effect.

Anilines (Aromatic Amines):

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

 For Fish Acute Toxicity Values: 2,3,5,6-Tetrachloroaniline is 19 times

more toxic than predicted by this SAR. Tetrabromoaniline may be more toxic

than predicted by this SAR as well.

 For Daphnid and Green Algae Toxicity Values: Tetrachloro- and tetrabromaniline may be 20 times toxic than predicted by this SAR.

 N-Substituted anilines are less toxic than predicted by these SARs;

for these compounds, Neutral Organic SARs are used.

ECOSAR v1.00 SAR Limitations:

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

Maximum LogKow: >7.8 (Fish 96-hr LC50, Daphnid 48-h LC50)

Maximum LogKow: >3.7 (Fish 14-day LC50)

Maximum LogKow: >4 (Green Algae 96-hr EC50 and ChV)

Maximum LogKow: >4.3 (Fish ChV)

Maximum LogKow: >2.4 (Daphnid ChV)

Maximum Mol Wt: 1000

Baseline Toxicity SAR Limitations:

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

Maximum LogKow: 5.0 (Fish 96-hr LC50; Daphnid LC50)

Maximum LogKow: 6.4 (Green Algae EC50)

Maximum LogKow: 8.0 (ChV)

Maximum Mol Wt: 1000

Screening Aquatic exposure analysis for parent primisulfuron-methyl

 RUN No. 1 FOR primisulfuronmet ON any * INPUT VALUES * 

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

 RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP

 ONE(MULT) INTERVAL Koc (PPM ) (%DRIFT) (FT) (IN)

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

 .036( .036) 1 1 66.0 70.0 AERL_A( 24.1) .0 .0
61

 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

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

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED

 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) 

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

 .00 2 N/A .00- .00 .00 .00

 GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001

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

 PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY

 GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC

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

 2.21 2.21 2.20 2.19 2.18