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Prepared 

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-3 of 43-

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 asulam (PC Code 106901) 

and its salt, sodium asulam (PC Code 106902). Asulam is a selective post-emergent systemic 

carbamate herbicide. The only end-use formulation of asulam is the sodium salt of asulam. One 

pound of the active ingredient (ai), sodium asulam, converts to 0.91 lbs acid equivalents (ae) 

asulam. Because under environmentally relevant conditions sodium asulam dissociates to the 

free acid, the risk assessment will be conducted on the basis of environmental exposure to 

asulam. This document will provide a plan for analyzing data relevant to asulam 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 sodium asulam. 

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 new 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 sodium asulam and asulam 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. 
-4 of 43-

2.2. Previous Risk Assessments 

A Registration Standard was issued in 1987, summarizing the available effects data for asulam. 

An ‘EFED List A Summary Report for Asulam,’ which included a risk assessment, was issued in 

1994. The risk assessment determined there was “a fairly high degree of certainty concerning 

LOC exceedances for terrestrial and semi-aquatic plants”. Additionally, “a high level of 

concern” exists for aquatic plants. 

A Reregistration Eligibility Decision (RED; USEPA 1995) was issued in 1995 which 

summarized the available environmental fate and effects data. The major conclusion from 

environmental risk assessment conducted in support of the RED was that use of asulam exceeded 

the levels of concern (LOCs) for endangered and non-endangered terrestrial and semi-aquatic 

plants for all uses. The Agency required additional environmental fate and ecological effects 

data to confirm the environmental and ecological risk assessment for all uses of asulam. 

In the RED, several risk mitigation measures were required for asulam, including: 

- prohibiting the aerial uses of asulam for non-cropland and Christmas trees use sites 

- clarifying the non-cropland use to limit 1 gallon/A rate, 1 application/season 

- clarifying the Christmas tree uses to limit 1 application/season 

- clarifying the turf use to limit use to state sod farms only and 1 application/season 

The Agency required a ground water label advisory and a surface water advisory for all asulam 

product registrations. Also, long term monitoring was deemed necessary in and near areas where 

asulam is used. 

A drinking water assessment was conducted and sent to the Health Effects Division (HED) in 

2002 (D279761). 

3. Stressor Source and Distribution 

3.1. Mechanism of Action 

“The physicochemical properties of asulam favor high phloem mobility, which contributes to the 

herbicidal activity against perennial weeds. The mode of action of asulam is unique for 

herbicides. It is an inhibitor of folic acid biosynthesis similar to the sulfonamide antimicrobial 

drugs, which are competitive inhibitors of 7,8-dihydropteroate synthase (DHPS). The 

mechanism of selectivity to asulam is reported as having greater metabolic degradation in 

tolerant species” (Pallett, 2003). 

3.2. Overview of Pesticide Use and Usage 

Asulam is a selective postemergent systemic carbamate herbicide used to control a variety of 

annual grasses and broadleaf weeds on sugarcane, spinach grown for seed, Christmas tree 

plantations, ornamentals, turf (St. Augustinegrass and Bermudagrass) and non-cropland uses 
-5 of 43-

(boundary fences, fencerows, hedgerows, lumberyards, storage areas and industrial plant sites, 

and warehouse lots). Its major use site is sugarcane. The only end-use formulation of asulam is 

soluble/concentrate liquid (sodium salt of asulam). Sodium asulam is applied by aerial or ground 

spray, broadcast, band, and spot treatment. Use practice limitations prohibit applying asulam 

through any type of irrigation system; discharging into bodies of water; using treated plants for 

feed or forage; and treating crops/sites within 90 days of harvest. 

There are currently eight Section 3 registered products as well as three SLN registrations for 

asulam (Table 3.1). 

TABLE 3.1. Summary of Registered Products Containing Asulam in the U.S. 

Registration # Name Company Name Percent Asulam 

002749-00523 Aceto Asulam 400 

Herbicide Aceto Agricultural Chemicals 33.0 

009779-00342 Asulam 3.3 

Herbicide Winfield Solutions 33.0 

034704-00904 Asulam Herbicide Loveland Products 33.0 

048273-00012 Asulam Herbicide Marman USA 33.0 

062719-00457 Asulam 400 Dow AgroSciences 33.0 

066330-00270 Asulam Liquid 

Herbicide Arysta LifeScience North America 33.0 

070506-00139 Asulox Herbicide United Phosphorus 33.0 

070506-00141 Asulox XP United Phosphorus 31.8 

OR07001600 Asulox Herbicide United Phosphorus 33.0 

OR10000800 Asulam Hebicide Loveland Products 33.0 

WA08000100 Asulox Herbicide United Phosphorus 33.0 

There is one registered food use on sugarcane. Sugarcane represents the greatest total 

application of sodium asulam of any use. Maximum single application for sugarcane is 3.653 lbs 

ai/A allowed twice at an unspecified interval for a total of 7.306 lbs ai/A allowed per crop cycle. 

Without a specified application interval, a conservative assumption will be used in the risk 

assessment. Explicitly stating the minimum interval would reduce uncertainty. The sugarcane 

use allows ground and aerial application. 

The spinach (for seed)use allows 1.3575 lbs ai/A allowed twice per crop cycle at a seven day 

interval, for a crop cycle total of 2.714 lbs ai/A. The spinach use is for seed crop only. The 

spinach use is geographically limited to Oregon and Washington States. Information on the 

number of crop cycles per year for spinach in these areas would be useful for the risk assessment. 

Application to spinach is limited to ground spray. 

Other non-food uses include ornamental turf, ornamental trees, shrubs and vines, Christmas 

trees, forest/shelterbelt (yew and juniper), rights of way and industrial area. All of these uses are 
-6 of 43-

limited to ground spray applications (no aerial) and a single application per crop cycle. Spot 

treatments are also allowed for some uses. The application rates are all generally 3.6 lbs sodium 

asulam per acre. A summary of currently registered sodium asulam uses, along with their 

respective methods and rates of application is presented in Table 3.2. 

Table 3.2. Registered Use Patterns for Sodium Asulam. 

According to the Biological and Economic analysis Division’s (BEAD) Screening Level Usage 

Analysis (SLUA; USEPA 2010), 700,000 lbs sodium asulam are applied annually on sugarcane 

and 70,000 lbs sodium asulam are applied annually to sod. The SLUA also reports that less than 

500 lbs are applied to sugar beets, although this is not a registered crop. The amount applied to 

spinach, ornamentals, Christmas trees, forestry or nonagricultural areas is not known. 

3.3. Environmental Fate and Transport 

At this time, the following environmental fate guidelines are not fulfilled for asulam: aerobic soil 

metabolism (835.4100), anaerobic soil metabolism (835.4200), aerobic aquatic metabolism study 

(835.4300), and terrestrial field dissipation (835.6100). The Agency has reviewed supplemental 

data submitted by the registrant to upgrade the aerobic and anaerobic soil, and aerobic aquatic 

metabolism studies, however the Agency still requires additional data for these guidelines. Also 

important for the validity of the laboratory and field studies, an investigation of the frozen 

storage stability of asulam and its degradate (sulfanilamide). These data gaps were reported in 

the 1995 RED, and it was stated at that time that the studies to support the soil/aquatic 

metabolism data requirements can be upgraded and other data requirements may have been 

fulfilled (e.g., storage stability data on asulam and its degradate). This data was never submitted 

therefore these data gaps still exist. Therefore, the lack of acceptable field dissipation data and 

the concerns about the integrity of data from the laboratory studies limit the Agency's ability to 

assess with confidence the environmental fate of asulam. The following assessment of the 

environmental fate of asulam is, in part, based on uncertain data. As a result, the fate, ground 

and surface water assessments of asulam may change after review of the additional data that 

remains outstanding. 

Use Pattern

Single 

App. Rate 

(lbs ai/A)

Number 

of App.

Seasonal 

App. Rate 

(lbs ai/A)

App. 

Interval 

(days)

Application 

Method Comments 

Spinach 1.3575 2 2.714 7 Ground spray 

Sugarcane 3.653 2 7.306 Not 

specified 

Aerial and 

ground spray 

Band and spot treatment 

allowed 

Ornamental turf 3.624 1 3.624 -- Ground spray 

Ornamental 

trees/shrubs/vines 3.653 1 3.653 -- Ground spray 

Nonagricultural 

areas and 

industrial areas 

3.644 1 3.644 -- Ground spray Spot treatments allowed 

Christmas trees 3.644 1 3.644 -- Mist blower 

Forest shelterbelt 

(yew and juniper) 3.644 1 3.644 -- Ground spray 
-7 of 43-

As stated previously, asulam (methyl sulfanilylcarbamate), is an herbicide used for weed control 

on sugarcane, spinach, Christmas tree plantations, ornamentals, turf, and noncropland uses. 

Asulam is formulated into and applied as the asulam sodium salt (sodium methyl 

sulfanilylcarbamate). 

Asulam Asulam, Sodium Salt 

Empirical Formula: C8H10N2O4S (asulam) 

C8H9N2NaO4S (asulam sodium salt) 

Molecular Weight: 230.2 (asulam) 

252.2 (asulam sodium salt) 

CAS Registry No.: 3337-71-1 (asulam) 

2302-17-2 (asulam sodium salt) 

PC Code: 106901 (asulam) 

106902 (asulam sodium salt) 

Asulam is a colorless, crystalline solid with a melting point of 143-145oC. Asulam sodium salt is 

a buff-colored powder with a melting point of 212-215oC. Asulam is soluble at approximately 

0.5% in water, and moderately soluble in chlorinated hydrocarbons, petroleum oils, and 

hydroxylic solvents. Asulam sodium salt is soluble at >100 g/100 mL in water at pHs 5, 6.5, and 

9. 

Table 3.4 summarizes the submitted environmental fate data for asulam. Additional 

characterization of the submitted environmental fate data is located in Appendix B. 

TABLE 3.4. General Chemical Properties and Environmental Fate Properties of Asulam, 

Sodium Salt. 

Parameter Value Reference (MRID #)

Physical/Chemical Parameters

Molecular mass (g/mol) 252.2 40751501 

Vapor pressure (25°C) <1 x 10-7 mmHg 40751501 

Henry’s Law Constant (25oC) 3.0 x 10-10 Footprint 

Water solubility (20°C) 534,000 mg/L 40751501 

Octanol-water partition coefficient (KOW) 1.01 (LogKow = 0.004) 40751501 

Dissociation constant (pKa) (25oC) 1.29 (strong acid) Footprint 
-8 of 43-

Parameter Value Reference (MRID #)

Mobility

Organic carbon partitioning coefficient (KOC, 

L·kg-1) 

115 (sand) 

63 (clay loam) 

69 (sandy clay loam) 

58 (sandy loam) 

18 (artificial Speyer 2.2) 

41215101 

Persistence in Water

Hydrolysis half-life (25°C, pH 5, 7, & 9) Stable 40997901 

Aqueous photolysis half-life (25°C) 2 hours 41326001

Aerobic aquatic metabolism half-life (20oC)† 105 days (loam:water) 41767803 

Anaerobic aquatic metabolism half-life (20oC) Stable 41767802 

Persistence in Soil

Soil photolysis half-life (25°C) 2 hours 41326002

Aerobic soil metabolism half-life (20°C) † 8 days (sand) 

28 days (sandy loam) 

23 days (loam) 

41767801 

Anaerobic soil metabolism half-life (20oC) Stable 41767802 

Field Dissipation

Terrestrial field dissipation half-life; 

maximum leaching depth 

No acceptable data -- 

Aquatic Bioconcentration 

Bioconcentration Factor (BCF) in fish Low Kow 

†

 Denotes uncertain data

Based on available data, the major routes of dissipation are leaching into ground water and biotic 

degradation under aerobic conditions. Asulam residues are considered mobile to highly mobile 

based on FAO Soil Mobility Classifications (USEPA, 2006). Due to its solubility in water, rain 

occurring immediately following application may increase the amount of chemical getting into 

ground water. Given the compound’s low Koc, sediment-bound runoff is not expected. 

Therefore, surface runoff could be another major route of dissipation. Based on the laboratory 

studies, photolysis in water and on soil appear to be major routes of degradation for asulam (halflife of 2 hours in water, and in soil; MRID 41326001, 41326002). However, the role of 

photolysis may be less significant under natural field conditions than in the laboratory due to the 

clarity of the water body and depth of the photolytic zone, as well as light intensity. This was 

demonstrated by the detection of low levels of asulam residues (0.1 ppb) in a surface water study 

(MRID 42704901). Based on acceptable data, the Agency concludes that asulam is very soluble 

in water, with a water solubility of 4,000 ppm, sodium salt of asulam is considered very highly 

soluble (>900,000 ppm). Asulam is stable to hydrolysis at pH's of 5, 7, and 9 (MRID 

40997901). Although this chemical photodegrades very rapidly in aqueous solution at pH 9, 

with a half-life of 2 hours, no degradation products were present at levels greater than 10 percent 

of the applied (MRID 41326001). 

On sandy loam soil, asulam was found to be readily photodegradable with a half-life of 1.5 hours 

(MRID 41326002). Sulfanilamide, the major degradation product formed on soil, was present at 

27.4 percent of the applied two hours after exposure to light (MRID 41326002). Based on the 
-9 of 43-

low vapor pressure of asulam (< 1 x 10-7), volatilization from soils will not be an important 

dissipation route (MRID 40751501). The low octanol/water partition coefficient suggests that 

asulam will have a low tendency to accumulate in fish (Kow of 1.01; MRID 40751501). Based 

on supplemental data, asulam is much less persistent under aerobic than anaerobic soil and 

aquatic conditions (half-life of 8-28 days in soil, 105 days in water; MRID 41767802, 

41767803). Under anaerobic conditions, biotic metabolism is reduced and leaching potential is 

enhanced (half-life was greater than one year; MRID 41767802). Sulfanilamide was the major 

degradate detected in the aerobic/anaerobic soil, and aerobic/anaerobic aquatic metabolism 

studies. Acetyl asulam (14.3% of the applied at 7 days) was only found in the soil incubated 

under anaerobic soil/aquatic environment. 

Asulam is expected to be very mobile due to its low soil adsorption coefficients (Kads ranges 0.6-

1.0, Koc ranges 18-115; MRID 41215101). Results from the column leaching studies for unaged 

and aged asulam residues showed that the parent compound has a high potential for leaching 

(MRID 40965001). Although no mobility studies were conducted for the degradate 

(sulfanilamide), based on the aged leaching study for asulam, sulfanilamide showed low mobility 

compared to the parent. 

Asulam has the physical/chemical characteristics in common with those pesticides that are 

known to leach to ground water or run off to surface water. Small amounts of asulam and 

sulfanilamide were detected in the leached soil columns. However, the dissipation of asulam in 

the field cannot be confirmed at this time because the registrant has not submitted any acceptable 

field dissipation data. Further, the field dissipation/small-scale prospective ground-water 

monitoring study provided little conclusive information due to the problems of residue analysis 

in the soil; however, it is adequate to allow the Agency to conclude that asulam is highly mobile 

and will likely reach ground water especially under the shallow ground-water conditions (MRID 

42534501). 

Results from an asulam drinking water survey of surface water indicate the presence of low 

levels of asulam (0.1 ppb) at the intakes to community water systems (MRID 42704901). This 

demonstrates the ability of the compound to move offsite into surface water. 

The lack of acceptable field dissipation data and the concerns about the integrity of data from the 

laboratory studies limit the Agency's ability to assess with confidence the environmental fate of 

asulam. The above assessment of the environmental fate of asulam was, in part, based on 

uncertain data. As a result, the fate, ground and surface water assessments of asulam may 

change after review of the additional data being required. 

 3.3.5. Bioaccumulation 

There are no data on the bioconcentration potential of asulam in fish. The octanol-water 

partition coefficient is sufficiently low, a value of 1.01 at 25o

 C (log KOW = 0.004; MRID 

40851501), that bioaccumulation in organisms is not expected. The EpiSuite estimate for the 

bioconcentration factor was 3.2 L·kg-1 wet-weight. This suggests that bioconcentration and 

bioaccumulation are not a concern. 
-10 of 43-

4. Receptors 

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

assessment for asulam and sodium asulam relies on a surrogate species approach. Toxicological 

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

taxonomic groups, are used to extrapolate the potential effects on a variety of species (receptors) 

included under these taxonomic groupings. 

Acute and chronic toxicity data from studies submitted by pesticide registrant, along with 

the available open literature, will be used to evaluate the potential direct and indirect effects of 

asulam to aquatic and terrestrial receptors. This includes toxicity on the technical grade active 

ingredient, degradates, and when available, formulated products (e.g., “Six-Pack” studies). Open 

literature studies were identified through EPA’s publically available ECOTOXicology 

(ECOTOX) database (November 2010), which employs a literature search engine for locating 

chemical toxicity data for aquatic and terrestrial plants and wildlife. The evaluation of both 

sources of data may also provide insight into the direct and indirect effects of asulam usage 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. 

A brief summary of the aquatic and terrestrial toxicity data available for the species most 

sensitive to asulam is provided in Sections 4.1 and 4.2, respectively. Most terrestrial and aquatic 

effects data were derived using asulam and are expressed in terms of acid equivalents (ae). A 

more complete summary of the available data is presented in Appendix B. In addition, a 

summary of ecological incidents associated with asulam and a description of ecosystems 

potentially at risk are provided in Sections 4.3 and 4.4, respectively. As noted previously, the 

sulfanilamide degradate forms to varying degrees under different environmental conditions. 

Toxicity data on the sulfanilamide degradate would reduce uncertainty in the risk assessment due 

to its variable formation and exposure to environmental receptors. 

Toxicity to fish and aquatic invertebrates is categorized using the system shown in Table 

4.1 (US EPA, 2004). Toxicity to terrestrial fauna (birds and mammals) is categorized using the 

system shown in Table 4.2. Toxicity categories for plants have not been defined. 

Table 4.1. Categories of Acute Toxicity for Aquatic Animals 

LC50 (ppm) Toxicity Category 

< 0.1 Very highly toxic 

> 0.1 - 1 Highly toxic 

> 1 - 10 Moderately toxic 

> 10 - 100 Slightly toxic 

> 100 Practically nontoxic 

Table 4.2. Categories of Acute Toxicity for Terrestrial Animals 

LD50 (mg/kg) LC50 (ppm) Toxicity Category 

<10 <50 Very highly toxic 

10-50 50-500 Highly toxic 
-11 of 43-

51-500 501 - 1000 Moderately toxic 

501-2000 1001 - 5000 Slightly toxic 

>2000 >5000 Practically nontoxic 

4.1. Effects to Aquatic Organisms 

The most sensitive aquatic toxicity data from registrant-submitted studies are provided in 

Table 4.3. There are several studies available in ECOTOX which will be reviewed for the risk 

assessment. Based on the available information, asulam is classified as to practically nontoxic to 

fish and slightly toxic aquatic invertebrates on an acute exposure basis. Both vascular and 

nonvascular aquatic plants are affected by asulam. 

Table 4.3. Aquatic Toxicity Profile for Asulam 

Taxonomic Group Species 

(Common Name) 

Endpoint 

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

Freshwater Fish 

Oncorhyncus 

mykiss 

(Rainbow Trout)

LC50>175 Practically nontoxic 40872001 

Freshwater 

Invertebrates 

Daphnia magna

(Waterflea ) EC50=27.1 Slightly toxic 00098507 

Estuarine/marine Fish -- -- -- --a

Estuarine/marine 

Invertebrates 

Palaemonetes 

pugio (grass 

shrimp) 

LC50>100 Practically nontoxic 00098508 

Vascular plants Lemna gibba

(duckweed) 

EC50=0.14 

NOAEC=0.07 --b

 42611701 

Nonvascular plants Pseudokirchneriella 

subcapitata 

EC50=0.18 

NOAEC=0.02 -- 42560301 

a

No data available 

b

 Toxicity categories for plants have not been defined. 

4.2. Effects to Terrestrial Organisms 

Table 4.3 summarizes the most sensitive terrestrial toxicity endpoints for asulam, based on an 

evaluation of the submitted data. Open literature studies have been identified through ECOTOX 

and will be reviewed for the risk assessment. Asulam is classified as practically nontoxic to 

terrestrial birds on an acute oral and subacute dietary exposure basis; asulam is classified as 

practically nontoxic to mammals on an acute oral exposure basis. No avian reproduction data 

has been submitted. Asulam is classified as practically nontoxic to young adult honey bees (Apis 

mellifera) on an acute contact exposure basis. 

As expected with an herbicide, asulam has adverse effects on plants. The studies were 

conducted with technical sodium asulam rather than typical end use product (TEP) as required 

under 40 CFR Part 158. Herbicidal active ingredients are usually formulated with adjuvants or 

surfactants that enhance the activity of the pesticide. Therefore, the sensitivity of terrestrial 

plants to formulated sodium asulam may be underestimated. 

Table 4.3 Terrestrial Toxicity Profile for Asulam 
-12 of 43-

Taxonomic Group Surrogate Species 

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

Birds 

Perdix perdix

(Partridge) LD50=3674.5 mg 

ae/kg bw Practically nontoxic 00056417 

Anas platyrhynchos

(Mallard duck) LC50>75,000 mg 

ae/kg diet Practically nontoxic 00056418 

Mammals Rattus norvegicus

(Laboratory rat) 

LD50>5000 mg 

ae/kg bw Practically non toxic 42110001 

Laboratory rat 

LOAEL=5000 

mg ae/kg-diet 

NOAEC=1000 

mg ae/kg-diet 

Reduced number of live 

births per litter 00098540 

Terrestrial 

Invertebrates

Apis mellifera

(Honey bee) 

LD50>36.26 

μg/bee Practically nontoxic 00018842 

Seedling 

emergence 

Lactuca sativa

(Lettuce) 

EC25=0.084 lbs 

ai/A 

NOAECa

=0.026 

lbs ai/A 

--b

 42613801 

Vegetative vigor Lactuca sativa

(Lettuce)

EC25=0.085 lbs 

ai/A 

NOAEC=0.044 

lbs ai/A 

-- 42613801 

a

EC05 used in lieu of a NOAEC 

b

 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 ae/kg-bw) are 

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

4.3. Incident Database Review 

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

asulam and sodium asulam was conducted on November 3, 2010. No incidents are reported in 

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

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

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

reported avian incidents involving pesticides did not report any incidents for asulam or sodium 

asulam as of November 3, 2010. Pesticide registrants report certain types of incidents to the 

Agency as aggregate counts of incidents occurring per product per quarter. One aggregate plant 

incident has been reported to the Agency associated with sodium asulam in an aggregated 

incident report from June, 2003. Although only one incident associated with the use of asulam 

or sodium asulam has been reported to the EPA, the lack of incident reports cannot be construed 

as the absence of incidents as there can be many reasons why the Agency is not notified of 
-13 of 43-

adverse effects resulting from the use of a pesticide. Unless additional information on this 2003 

aggregated incident report becomes available, it will be assumed to be due to a registered use of 

asulam in the risk assessment. 

4.4. 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 are defined as “explicit expressions of the actual environmental value that 

is to be protected.”1

 Selection of the assessment endpoints is based on valued entities (e.g., fish, 

birds), the ecosystems potentially at risk (e.g., waterbodies, riparian vegetation, and upland 

habitats), the migration pathways of asulam (e.g., runoff, drift, etc.), and the routes by which 

ecological receptors are exposed to asulam (e.g., direct contact, etc.). 

Assessment endpoints for asulam include direct toxic effects on the survival, reproduction, and 

growth of the receptors, as well as indirect effects, such as reduction of the prey base or 

modification of habitat. Each assessment endpoint requires one or more “measures of ecological 

effect,” defined as changes in the attributes of an assessment endpoint or changes in a surrogate 

entity or attribute in response to exposure to a pesticide. Specific measures of ecological effect 

are generally evaluated based on acute and chronic toxicity information from registrantsubmitted guideline tests that are performed on a limited number of organisms. Additional 

ecological effects data from the open literature will also be considered. 

 

1

 From U.S. EPA (1992). Framework for Ecological Risk Assessment. EPA/630/R-92/001. 
-14 of 43-

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 asulam provides a written description (risk hypothesis) and visual 

representation (conceptual diagram) of the predicted relationships between asulam, potential 

routes of exposure, and the predicted effects for the assessment endpoint. A conceptual model 

consists of two major components: risk hypothesis and a conceptual diagram (USEPA 1998b). 

Based on the available data (including those from uncertain studies), asulam (sodium asulam) is 

highly to very highly soluble, stable in water without light, unstable in water and on soil under 

light; however, small amounts of asulam were detected in surface water. Asualm is relatively 

unstable in soil under aerobic conditions, but very stable in soil and sediment under anaerobic 

conditions. It is very mobile in soil, asulam is not volatile, and will not likely accumulate in 

aquatic food webs. With these properties, it appears that asulam is highly mobile and has a strong 

potential to leach into ground water or move offsite into surface water. The Agency has 

concluded from the small-scale prospective ground-water studies that asulam will likely reach 

ground water especially under the shallow ground-water conditions. Given its relatively low 

Kow, asulam is not expected to bioaccumulate in aquatic or terrestrial food chains. 

6.1. Risk Hypothesis 

A risk hypothesis describes the predicted relationship among the stressor, exposure, and 

assessment endpoint response along with the rationale for their selection. For asulam, the 

following ecological risk hypothesis will being employed for the national-level ecological risk 

assessment: 

Given the uses of asulam and its environmental fate properties, there is a likelihood of exposure 

to non-target terrestrial and aquatic organisms. When used in accordance with the label, 

asulam may result in potential adverse effects upon the survival, growth, and reproduction of 

non-target terrestrial and aquatic organisms. 

6.2. Conceptual Diagram 

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

asulam (the stressor) assumes that as a pesticide, asulam 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 (Figure 1). Ecological receptors that may 

potentially be exposed to asulam include terrestrial and semi-aquatic wildlife (e.g., mammals, 

birds, terrestrial-phase amphibians and reptiles), terrestrial and semi-aquatic plants, and 
-15 of 43-

terrestrial invertebrates (e.g., honey bees) (Figure 2). Additionally, given the mobility of 

asulam, aquatic organisms (i.e., freshwater and estuarine/marine fish and invertebrates, aquaticphase amphibians, and aquatic plants) are potential receptors in adjacent water bodies through 

off-site transport of asulam from the application site through runoff, erosion, spray drift. 

Figure 1. Conceptual model for asulam exposure to aquatic organisms. Dashed lines indicate 

route of exposure considered of lower importance for asulam.

Stressor 

Source

Receptors 

Attribute 

Change 

Sodium Asulam 

(and degradates) 

Spray drift 

Fish/aquatic-phase 

amphibians 

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/ 

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 
-16 of 43-

Figure 2. Conceptual model for asulam exposure to terrestrial organisms. Dashed lines 

indicate route of exposure considered of lower importance for asulam.

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 asulam 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 often defined as the 

likelihood and magnitude of adverse ecological effects, the risk quotient-based 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 asulam may be estimated using the probit doseresponse 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 asulam. 

Stressor 

Source

Receptors 

Attribut

e 

Sodium Asulam 

(and degradates) 

Direct 

application 

Spray drift

Birds / Terrestrialphase amphibians 

/ reptiles / 

mammals/ Insects 

Terrestrial 

insects 

Individual organisms 

Reduced survival 

Reduced growth 

Reduced reproduction

Food chain 

Reduction in 

Habitat integrity 

Reduction in primary 

productivity

Reduced cover

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

Ingestio
-17 of 43-

7.1. Stressors of Concern 

The stressor of concern in the assessment will be asulam. As previously discussed, technical 

sodium asulam is expected to dissociate to asulam acid when mixed with water for spray 

applications and remain in the acid form under environmentally relevant conditions alone. 

There are no known applications of specific mixtures of asulam with other chemicals. In its 

ecological risk assessments, 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 Document and the Services’ Evaluation Memorandum (USEPA, 2004; 

Williams and Hogarth, 2004). 

7.2. Measures of Exposure 

In order to estimate risks of asulam exposures in aquatic and terrestrial environments, exposure 

modeling will be based on maximum application rates and methods cited in Table 3.2. Measures 

of exposure are based on aquatic and terrestrial models that predict estimated environmental 

concentrations (EECs) of asulam. The models used to predict aquatic EECs are the Pesticide 

Root Zone Model coupled with the Exposure Analysis Modeling System (PRZM/EXAMS). 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 and wetland plants is TerrPlant. 

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 (v3.12.2; 5/15/05) and EXAMS (v2.98.04.06; 4/25/05) are simulation models coupled 

with the linkage program shell: PE5 (PRZM EXAMS Model Shell; v5.0; 11/15/06), which 

incorporates the standard scenarios developed by EFED. The models generate daily exposures 

and calculated 1-in-10 year EECs of asulam and possibly (depending on the outcome of 

environmental fate studies) toxicologically significant degradatation products (e.g., 

sulfanilamide). 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 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 
-18 of 43-

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 asulam. 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. 

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 (version 1.4.1, 10/09/2008). 

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

dissipation half-life in the absence of other data. 

The Screening Imbibition Program (SIP v.1.0, Released June 15, 2010) was used to calculate an 

upper bound estimate of exposure using asulam’s solubility (534,000 ppm), the most sensitive 

acute and chronicavian toxicity endpoints (LD50=3674.5 mg ai/kg-bw; NOAEL not available) 

and the most sensitive acute and chronic mammalian toxicity endpoints (enter mammalian 

species with LD50=5000 mg ai/kg-bw and NOAEL=1000 mg ai/kg-diet). Drinking water 

exposure alone was determined to be a potential pathway of concern for avian and mammalian 

species on an acute and chronic basis (avian chronic assumed due to lack of data). 

This pathway will be explored further with the development of SIP v.2.0 in the risk assessment 

for asulam. 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 (version 1.2.2, 12/26/2006). 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 (v2.01; May 2001) or AgDisp (version 8.15) spray drift model may be used to 

assess exposures of organisms to asulam deposited on terrestrial habitats by spray drift. 
-19 of 43-

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. 

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 non-listed 

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 asulam to birds is similar to terrestrial-phase 

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

In the absence of data for either acute or chronic effects, the conservative assumption will be to 

presume that asulam is toxic. 

7.4. Integration of Exposure and Effects 

Risk characterization is the integration of exposure and ecological effects characterization to 

determine the potential ecological risk from the registered uses of asulam and the likelihood of 

direct and indirect effects to non-target organisms in aquatic and terrestrial habitats. 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 asulam 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 Agency’s Levels 

of Concern (LOCs) (USEPA 2004). These criteria are used to indicate when asulam 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. 
-20 of 43-

7.5. 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. 

7.6.. Endocrine Disruptor Screening Program 

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. 

Asulam 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/. 

7.7. Endangered 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 
-21 of 43-

registered uses of sodium asulam. 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 asulam 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 asulam application 

occurs), plus all areas where offsite transport (i.e., spray drift, 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 asulam is used in the United States. 

7.8. Drinking Water Assessment 

In order to bring the drinking water exposure assessment up to date with current data, models 

and simulation model guidance, a new drinking water assessment will be conducted to support 

future human health dietary risk assessments of asulam. 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 

asulam alone in surface water and ground water including any residues that are determined to be 

of toxicological concern. Concentrations of asulam 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 asulam in ground water will be 

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

Water, version 2.3; 8/8/2003). 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. If significant amounts of asulam are 

found to deposit in the environment due to releases from the potato storage facility use, a 

drinking water assessment will be performed for this use using PRZM/EXAMS and SCIGROW. 

In this case, the deposited residues will be treated as if they were a soil application of a pesticide 

in PRZM. 
-22 of 43-

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. 

8.0. Preliminary Identification of Data Gaps 

 8.1. Environmental Fate 

The studies submitted to fulfill environmental fate data requirements for asulam/sodium asulam 

are not sufficient to conduct an exposure assessment; five requirements have not been met as 

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

terrestrial food and nonfood applications: 1) There is only one supplemental aerobic aquatic 

metabolism study, and additional data on the sample processing times is needed to upgrade this 

study. This study is necessary in order to describe the fate of asulam in surface water bodies 

down-gradient from terrestrial use sites. 2) There is only one supplemental aerobic soil 

metabolism study conducted three soils. Additional data on the sample processing times is 

needed to upgrade this study. The guideline stipulates that results from at least four relevant soils 

of different organic carbon content, pH, clay content, and microbial biomass must be submitted 

in order to characterize the variability in aerobic biodegradation of asulam in the environment 

(currently the Agency has three). 3) Submission of an acceptable anaerobic aquatic metabolism 

study using an additional sediment: water system is necessary to understand the degradation of 

asulam in oxygen-limiting environments. 4) An acceptable terrestrial field dissipation study is 

required for all pesticides with use patterns for terrestrial food and nonfood applications. 5) 

Submission of a storage stability study is essential in order to be confident that any degradation 

measured in the test system was due solely to the environment of that test system, and not due to 

handling and storage. Lastly, although not necessary for exposure assessment, submission of an 

environmental chemistry method in water, soil, and sediment as well as associated independent 

laboratory validations for these methods is also necessary in order to support enforcement and 

monitoring purposes at the federal, state, and local levels. 

Data Call-In tables for the anticipated data needs are provided in APPENDIX A. Table 8.1

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 8.1. Summary of available environmental fate data. 

Guideline Study Title MRID Classification Data Gap? Comments 

835.2120 Hydrolysis 

40997901 Acceptable 

No 

No significant issues affecting the acceptability of 

the study were noted. 

00098513 Unacceptable 

Material balance for the first sample was incomplete 

having not accounted for up to 20% of the test 

material. 

835.2240 Photodegradation 

in Water 41326001 Acceptable No No significant issues affecting the acceptability of 

the study were noted. 
-23 of 43-

Guideline Study Title MRID Classification Data Gap? Comments 

00047845 Unacceptable 

Sampling protocol was inadequate (too few samples, 

no dark controls, incubation temp was not reported). 

Analytical methods were incomplete. No immediate 

posttreatment samples and the test solutions were 

uncharacterized. Degradates were not addressed. 

Artificial light was incompletely characterized and 

not compared to natural sunlight. Conclusions were 

not supported by data. 

00098514 Unacceptable 

Material balances were incomplete. Degradates were 

not identified, and artificial light source was not 

adequately compared to natural sunlight. 

835.2410 Photodegradation 

on Soil 

41326002 Acceptable 

No 

No significant issues affecting the acceptability of 

the study were noted. 

00098515 Unacceptable 

No samples were taken immediately posttreatment. 

Artificial light source was not reported (and 

intensity), and was not compared to natural sunlight. 

Soils were not classified according to the USDA 

textural classification system. 

835.4100 Aerobic Soil 

Metabolism 

00098516 Unacceptable 

Yes 

The soil was not classified according to the USDA 

Soil Textural Classification System, and the 

incubation temperature was not constant. Degradates 

were not accurately characterized. 

00084802 Unacceptable 

The sampling protocol was inadequate to assess the 

decline of asulam in soil and the material balance 

was incomplete. The purity of the test substance was 

not specified. The soil was not classified according to

the USDA Soil Textural Classification System, and 

the CEC of the soil was not reported. 

41767801 Supplemental /

Upgradable 

Previous studies indicated that freezing storage can 

affect residue characterization. Additional data is 

needed to support the registrant’s claim that sample 

processing occurred immediately following 

sampling. 

835.4200 Anaerobic Soil 

Metabolism 

00098517 Unacceptable 

Yes 

Soil samples were incubated aerobically for longer 

than one half-life prior to establishing anaerobic 

conditions. Degradates were not accurately 

characterized. The soil was not classified according 

to the USDA Soil Textural Classification System, 

and incubation temperature was not held constant. 

41767802 Supplemental / 

Upgradable 

Previous studies indicated that freezing storage can 

affect residue characterization. Additional data is 

needed to support the registrant’s claim that sample 

processing occurred immediately following 

sampling. 

835.4300 Aerobic Aquatic 

Metabolism 41767803 Supplemental / 

Upgradable Yes 

Previous studies indicated that freezing storage can 

affect residue characterization. Additional data is 

needed to support the registrant’s claim that sample 

processing occurred immediately following 

sampling. 

835.4400 

Anaerobic 

Aquatic 

Metabolism 

41767802 Supplemental/ 

Upgradable Yes 

Previous studies indicated that freezing storage can 

affect residue characterization. Additional data is 

needed to support the registrant’s claim that sample 

processing occurred immediately following 

sampling. 
-24 of 43-

Guideline Study Title MRID Classification Data Gap? Comments 

00098518 Unacceptable 

Data were too variable to accurately assess the 

decline of asulam. The material balance was 

incomplete, and degradates were not accurately 

characterized; up to 29% of the applied radioactivity 

was not accounted for. Physical parameters of study 

water were not characterized. The soils were not 

classified according to the USDA Textural 

Classification System. 

835.1240 Mobility - 

Adsorption / 

Desorption 

40965001 Acceptable 

No 

No significant issues affecting the acceptability of 

the study were noted. 

00084801 Unacceptable 

The material balance was incomplete, the purity of 

the test substance is not specified, the CEC of the soil

is not reported, distribution curves of asulam 

throughout the soil columns are not determined, the 

total amount of water leached through each soil 

column was not specified. 

835.1230 41215101 Acceptable No significant issues affecting the acceptability of 

the study were noted. 

835.6100 Terrestrial Field 

Dissipation 

00044578 Supplemental/ 

Upgradeable 

Yes 

The effects of storage on the recoveries of asulam 

and its degradation products as well as their 

subsequent binding to organic matter in soil could 

not be evaluated. Previous studies indicated that 

frozen storage can affect residue characterization. 

00098527 Unacceptable 

Field test data were incomplete, the CEC of the soils 

was not reported. Frozen storage stability data have 

not been submitted. Residues in the soil immediately 

following treatment do not reflect the application 

rates (material was unaccounted for). 

00098529 Unacceptable 

The application rate was not confirmed by 

immediately following treatment sampling, residues 

in crops and soils were not characterized, soil was 

not sampled at the time of treatment or planting, and 

field test data were incomplete. 

00098530 Unacceptable 

Field test data were incomplete, the CEC of the soils 

was not reported, and the soils were not sampled 

deep enough to define the extent of leaching. 

00114872 Unacceptable 

The test substance was not characterized, the soil was 

incompletely characterized, field test data were 

incomplete, the soils were not sampled deep enough 

to define the extent of leaching, storage conditions 

were not reported, storage stability data were not 

provided, and residues in the soil immediately posttreatment do not appear to reflect the application rate.

850.1730 Fish 

Accumulation 00098511 Unacceptable No 

Residues in the water and fish were not 

characterized; however, this study is not required 

because the KOW is significantly below 1000. 

835.7100 

Prospective 

Groundwater 

Monitoring 

42534501 Supplemental No 

This study provided little conclusive information due 

to the problems of residue analysis in the soil; 

however, it is adequate to allow the Agency to 

conclude that asulam is highly mobile and will likely 

reach ground water especially under the shallow 

ground-water conditions. 

Non-guideline Drinking Water 

Monitoring 42704901 Supplemental NA -- 
-25 of 43-

8.2. Effects 

The available ecological effects data for asulam/sodium asulam consists primarily of acute 

effects studies on animals and effects to plants. There are no data on the potential for chronic 

effects to fish, invertebrates or avian species. There are no acute data on estuarine/marine fish. 

Additionally, an avian acute oral study with a passerine is now required under the current 40 

CFR Part 158 and is not yet been submitted for asulam. Available data on the toxicity of asulam 

to terrestrial plants are based on technical sodium asulam rather than the required TEP. 

Therefore effects to non-target plants may be appreciably underestimated by the available 

studies. The available effects studies for asulam are presented in Tables 8.2-8.4.
-26 of 43-

TABLE 8.2. Available ecological effects data for terrestrial animals exposed to asulam

Guideline Description MRID/ 

Accession Classification Data Gap? Comments 

850.2100 Avian oral toxicity 00056417 Supplemental Yes* *Avian acute oral toxicity data 

are not available for 

passerines, which are required 

under the new 40 CFR Part 

158. Therefore, this is 

identified as a data gap. 

850.2200 Avian dietary 

toxicity 

00056418 

00056419 

Supplemental No 

850.2300 Avian reproduction None Yes 

850.3020 Honeybee acute 

contact toxicity 00018842 Acceptable No 

TABLE 8.3. Available ecological effects data for aquatic animals exposed to asulam.

Guideline Description MRID/ 

Accession Classification Data Gap? Comments 

850.1075 Freshwater fish – 

Acute toxicity 

40872001 Acceptable 

No In the absence of data, risk 

will be presumed 00098505 Acceptable 

00054621 Supplemental 

850.1075 Saltwater fish – 

Acute toxicity None Yes 

850.1010 

Freshwater 

invertebrates – 

Acute toxicity 

40977602 Acceptable 

No 

00098507 Acceptable 

850.1025 

850.1035 

Saltwater 

invertebrates –Acute 

toxicity 

00098508 Acceptable 

00098509 Acceptable No 

41000701 Supplemental 

850.1300 

Freshwater 

invertebrate – 

 life cycle test 

None Yes 

850.1350 

Saltwater 

invertebrates – 

life cycle test 

None Yes 

850.1400 Freshwater fish – 

early life stage test None Yes 

850.1400 Saltwater fish – 

early life stage test Yes 
-27 of 43-

TABLE 8.4. Available ecological effects data for plants exposed to asulam.

Guideline Description MRID Classificatio

n 

Data 

Gap? comments 

850.4100 

Terrestrial Plant 

toxicity: Tier I seedling 

emergence 

42613801 Supplemental Yes Data on the phytotoxicity of 

formulated product with 

sodium asulam are necessary 

to estimate the distance to 

where listed may be affected. 850.4150 

Terrestrial Plant 

toxicity: Tier I 

vegetative vigor 

42613801 Supplemental Yes 

850.4400 Aquatic Plant Growth: 

algae 42560301 Acceptable No 

850.4400 Aquatic Plant Growth: 

vascular plants 42611701 Acceptable No 

8. 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. 

Pallett, K. E. 2003. Herbicides, Asulam in: Encyclopedia of Agrochemicals. 

http://dx.doi.org/10.1002/047126363X.agr025 

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, 1995. Reregistration Eligibility Decision, Asulam, List A, Case 0625. 

http://www.epa.gov/oppsrrd1/REDs/0265.pdf. 

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 
-28 of 43-

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

Environmental Contamination and Toxicology. 100:23-73. 

Submitted Fate Studies 

MRID Citation Reference 

00098513 Maycey, P.A. and J.B. Unsworth (1981) Asulam: Hydrolysis Studies with Asulam-Ring14C. AG/Tech 56. Unpublished Study Received April 16, 1982 under 359-662; Prepared 

by May & Baker Ltd., England and Submitted by Rhone-Poulenc Chemical Co., Monmouth 

Junction, NJ, CDL:070773-B. 

40997901 Gohdes, M. (1989) Hydrolysis of ?Carbon 14|-Asulam in Buffered Aqeous Solutions: Proj. 

ID. HLA 6224-122. Unpublished study prepared by Hazleton Laboratories America, Inc. 62 

p. 

00084798 Mulcock, P.A. (1971) Asulam: Photostability Studies: RG/1161. (Un- published study 

received Nov 8, 1972 under 3F1331; prepared by May & Baker, Ltd., England, submitted 

by Rhodia, Inc., New Brunswick, N.J.; CDL:094626-J) 

00097845 

or 

00047845 

Tattersfield, C.R. (1972) Asulam: Photochemical Degradation: RG/ 1438. (Unpublished 

study received Nov 8, 1972 under 3F1331; prepared by May & Baker, Ltd., England, 

submitted by Rhodia, Inc., New Brunswick, N.J.; CDL:094626-K) 

00098514 Williams, C.M. and E.A. Savage (1981) Asulam: Photodegradation in Aqueous Solution. 

AG/Tech 112. Unpublished Study Received April 16, 1982 under 359-662; Prepared by 

May & Baker Ltd., England and Submitted by Rhone-Poulenc Chemical Co., Monmouth 

Junction, NJ, CDL:070773-C. 

41326001 Fathulla, R. (1989) Artificial Sunlight Photodegradation of ?Carbon - 14|-Asulam in a 

Buffered Aqueous Solution: Lab Project Number: HLA/6224/123. Unpublished study 

prepared by Hazleton Laboratories America, Inc. 108 p. 

00098515 Jones, A.G. and J.B. Unsworth (1981) Asulam: Photodegradation in Soil. AG/Tech 48. 

Unpublished Study Received April 16, 1982 under 359-662; Prepared by May & Baker 

Ltd., England and Submitted by Rhone-Poulenc Chemical Co., Monmouth Junction, NJ, 

CDL:070773-D. 

41326002 Obrist, J. (1989) Artificial Sunlight Photodegradation of ?Carbon - 14|-Asulam on Soil: Lab 

Project Number: HLA/6224/124. Unpublished study prepared by Hazleton Laboratories 

America, Inc. 96 p. 

00098528 Jones, A.G. (1977) Herbicides: Asulam Distribution Studies in Two Loam Soils: AR/1212. 

(Unpublished study received Apr 16, 1982 under 359-662; prepared by May & Baker Ltd., 

England, submitted by Rhone-Poulenc Chemical Co., Monmouth Junction, N.J.; CDL: 

070774-B) 

00098516 Smith, C.A., J.B. Unsworth and J. Franklin (1981) Asulam: Metabolism in Soil under 

Aerobic Conditions. Report No. 1819. Unpublished Study Received April 16, 1982 under 

0098516; Prepared by May & Baker Ltd., England and Submitted by Rhone-Poulenc 

Chemical Co., Monmouth Junction, NJ, CDL:070773-E. 

00098517 Unsworth, J.B., C.A. Smith and J. Franklin (1981) Asulam: Metabolism in Soil under 

Anaerobic Conditions. Report No. AP/1820. Unpublished Study Received April 16, 1982 

under 359-662; Prepared by May & Baker Ltd., England and Submitted by Rhone-Poulenc 
-29 of 43-

Chemical Co., Monmouth Junction, NJ, CDL:070773-F. 

00084802 Edwards, R.A. (1972a) Asulam: Metabolic Studies with Asulam (Ring 14C). Rg/1433. 

Unpublished Study Received Nov. 8, 1972 under 3F1331; Prepared by May and Baker, 

Ltd. England, and Submitted by Rhodia, Inc., New Brunswick, NJ. CDL:094526-O. 

41767801 Godward, P.; Fisher, P.; Lowden, P; et al. (1990) Asulam ?carbon 14|: (Na Salt): Aerobic 

Soil Metabolism ?supplement to MRID 41743301|: Lab Project Number P88/086: P90/385. 

Unpublished study prepared by Rhone-Poulenc Agriculture. 139 p. 

41767803 Gowdard, P.; Fisher, P.; Lowden, P.; et al. (1991) Asulam ?carbon 14| (Na Salt): Aerobic 

Aquatic Soil Metabolism ?supplement to MRID 41743303|: Lab Project Number: 

P89/217. Unpublished study prepared by Rhone-Poulenc Agriculture. 122 p. 

41767802 Godward, P.; Fisher, P.; Lowden, P.; et al. (1991) Asulam ?carbon 14|: (Na-Salt): 

Anaerobic Aquatic Soil Metabolism ?supplement to MRID 41743302|: Lab Project 

Number: P88/087: 162-3. Unpublished study prepared by Rhone-Poulenc Agriculture. 112 

p. 

00098518 Turner,G.M.., J.B. Unsworth and J. Franklin (1981) Asulam: Metabolism in Pond and River 

Sediments (Anaerobic Aquatic). AG/Tech 52. Unpublished Study Received April 16, 1982 

under 359-662; Prepared by May & Baker Ltd., England and Submitted by Rhone-Poulenc 

Chemical Co., Monmouth Junction, NJ, CDL:070773-G. 

00056428 Hewett, R.H. (1971) Asulam (Herbicide): Soil Mobility and Soil Persistence Studies Using 

Bioassay Techniques: Ongar 1971: Report No. AR 651. (Unpublished study received Jun 

11, 1972 under 2G1200; prepared by May & Baker, Ltd., submitted by Rhodia, Inc., New 

Brunswick, N.J.; CDL:091017-AE) 

00056429 Guardigli, A. (1971) Leaching Studies on Asulam: Laboratory Exper- iments. (Unpublished 

study received Jun 11, 1972 under 2G1200; submitted by Rhodia, Inc., New Brunswick, 

N.J.; CDL:091017-AF) 

00113839 Jones, A. (1977) Herbicides: Asulam--Distribution Studies in Two Loam Soils: AR/1212. 

(Unpublished study received May 4, 1977 under 359-662; prepared by May & Baker, Ltd., 

Eng., submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:230626-A) 

00127712 Nomura, N. (1978) Adsorption and Mobility of VEL 5026-14C in Five Hawaiian Sugarcane 

Soils. (Unpublished study received Aug 21, 1978 under 876-EX-36; prepared by Hawaiian 

Sugar Planters' As- soc., submitted by Velsicol Chemical Corp., Chicago, IL; CDL: 

234819-H) 

00098525 Cooper, I.C. and J.B. Unsworth (1981) Asulam: Leaching Study with 

Four Soils. AG Tech. 19. Unpublished Study Received Apr. 16, 1982 under 359-662; 

Prepared by May and Baker and Baker, Ltd., England, and Submitted by Rhone-Poulenc 

Chemical Co., Monmouth Junction, NJ ; CDL:070773-N. 

00098526 Savage, E.A. and P.I. Podward. 1981. Asulam Sorption study with Four Soils : AG Tech. 

27. Unpublished Study Received Apr. 16, 1982 under 359-662; Prepared by May and 

Baker, Ltd., Submitted by Rhone-Poulenc Chemical Co., Monmouth Junction, NJ; CDL: 

070773-0. 

00134842 Nomura, N. (1978) Adsorption and Mobility of VEL 5026-14C in Five Hawaiian Sugarcane 

Soils. (Unpublished study received July 12, 1978 under 876-EX-35; Prepared by Hawaiian 

Sugar Planters' Assoc. and submitted by Velsicol Chemical Corp., Chicago, IL; CDL: 

234423-J). 

40965001 Reeves, G.; England, D.; Savage, E. (1988) Herbicides: Asulam-?Car- bon 14|: Leaching 

Study with Four Soils: Laboratory Project ID: D. Ag. 1118. Unpublished study prepared by 

Rhone-Poulenc Agri- culture. 83 p. 
-30 of 43-

41215101 Godward, P.; England, D.; Savage, E. (1988) Herbicides: Asulam - ?carbon 14| (Na Salt) 

Adsorption/Desorption on Five Soils: Pro- ject ID: D.Ag.1119. Unpublished study prepared 

by Rhone-Poulenc Agriculture. 82 p. 

00044578 Cooley, A.W.; Harper, D.; Burr, R.; et al. (1975) Residue Study of Asulam, Its Impurity and 

Metabolites in/on Alfalfa Forage and Soil: Report No. 75/107/NB/AG. (Unpublished study 

received Dec 17, 1975 under 6F1716; prepared in cooperation with Oregon State Univ., 

submitted by Rhodia, Inc., New Brunswick, N.J.; CDL: 095193-C) 

00098527 Guyton, C.L.; Chow, W.; Guardigli, A. (1981) Asulam Residue Data on Soil Treated PPI in 

1976 and 1977: PDD No. 81/017. (Unpub- lished study received Apr 16, 1982 under 359-

662; submitted by Rhone-Poulenc Chemical Co., Monmouth Junction, N.J.; CDL: 070774-

A) 

00098529 Jones, A.G. (1981) Asulam: Residues in Crops Grown in Soil Treated with Asulam-

?~ring~?^14IC: AG.Tech/55. (Unpublished study re- ceived Apr 16, 1982 under 359-662; 

prepared by May & Baker Ltd., England, submitted by Rhone-Poulenc Chemical Co., 

Monmouth Junction, N.J.; CDL:070774-C) 

00098530 Guyton, C.L.; Somma, N.; Guardigli, A. (1982) Asulam Residue Data on Crops and Soil 

from a Long Term Persistence Study: 1976-1979: PDD No. 82/027. (Unpublished study 

received Apr 16, 1982 under 359-662; submitted by Rhone-Poulenc Chemical Co., 

Monmouth Junction, N.J.; CDL:070774-D) 

00114872 Rhodia, Inc. (1975) Residue Study of Asulam and Metabolites in Field Sugar Cane Soil. 

(Compilation; unpublished study received Apr 11, 1975 under 3F1331; CDL:094625-A) 

42534501 Norris, F. (1992) A Small Scale Prospective Groundwater Monitoring Study with AsulamSodium, the Active Ingredient of Asulox Brand Herbicide Applied to Sugar Cane and to 

Turf: Progress Report: Lab Project Number: EC-89-068: EC/89/069: 920105. Unpublished 

study prepared by Rhone-Poulenc. 17 p. 

41803901 Norris, F. (1991) A Small Scale Prospective Groundwater Monitoring Study with AsulamSodium, the Active Ingredient of Asulox Brand Herbicide, Applied to Sugar Cane and to 

Turf: Lab Project Num- ber: 40949: EC-89-068: EC-89-069. Unpublished study prepared 

by Rhone-Poulenc Ag Co., A & L Eastern Agricultural Laboratories, Inc., Analytical 

Development Corp., and CYAL. 180 p. 

42704901 Gustafson, D. (1993) Drinking Water Monitoring for Residues of Asulam in High-use Areas 

of the United States: Lab Project Number: 41293: EC-91-153. Unpublished study prepared 

by Alta Analytical Laboratory, Inc. 164 p. 

 

Submitted Effects Studies 

71-1 Avian Single Dose Oral Toxicity 

MRID Citation Reference 

56417 Ingham, B. (1971) Herbicides: Asulox 40: Acute Oral Toxicity in Mallard, 

Partridges, Pheasants and Pigeons: Report No. RG/1108. (Unpublished 

study received Jun 11, 1972 under 2G1200; prepared by May and 

Baker, Ltd., England, submitted by Rhodia, Inc., New Brunswick, N.J.; 

CDL:091017-T) 
-31 of 43-

71-2 Avian Dietary Toxicity 

MRID Citation Reference 

56418 Heywood, B.A.; Ingham, B. (1970) Asulox: Subacute (5 Day) Toxicity in 

Mallard Ducklings: Report No. RG/857. (Unpublished study received 

Jun 11, 1972 under 2G1200; prepared by May and Baker, Ltd., 

England, submitted by Rhodia, Inc., New Brunswick, N.J.; CDL:091017-

U) 

56419 Heywood, B.A.; Ingham, B. (1970) Asulox: Subacute (5 Day) Toxicity 

Study in Pheasant Chicks: Report No. RG/867. (Unpublished study 

received Jun 11, 1972 under 2G1200; prepared by May and Baker, Ltd., 

England, submitted by Rhodia, Inc., New Brunswick, N.J.; CDL:091017-

V) 

72-1 Fish Acute Toxicity 

56421 Fraser, W.D.; Jenkins, G. (1970) The Acute Toxicity of Asulam to 

Rainbow Trout, Goldfish, Channel Catfish and Bluegill: Report No. 

3639/70/451. (Unpublished study received Jun 11, 1972 under 2G1200; 

prepared by Huntingdon Research Centre, England, sub- mitted by 

Rhodia, Inc., New Brunswick, N.J.; CDL:091017-X) 

98505 Vilkas, A.G.; Kuc, W.J. (1979) The Acute Toxicity of Asulam Tech- nical to the Bluegill 

Sunfish~Lepomis macrochirus~Rafinesque: UCES Project No. 11506-48-06. 

(Unpublished study received Apr 16, 1982 under 359-662; prepared by Union Carbide 

Corp., submit- ted by Rhone-Poulenc Chemical Co., Monmouth Junction, N.J.; 

CDL:070772-A) 

40872001 Manning, C. (1988) Acute Toxicity of Asulam Technical to Rainbow Trout (Salmo 

gaidneri) Under Static Conditions: Project ID: ese No. 89325-0400-2130. Unpublished 

study prepared by Hunter/ ESE, Inc. 76 p. 

 
-32 of 43-

72-2 Acute Toxicity to Freshwater Invertebrates 

MRID Citation Reference 

 

98507 Roberts, S.; Parke, G.S.E.; Charles, S. (1977) Static 48-hour Toxicity Study of Asulam 

Technical in Daphnids: Laboratory No. 7E-7665. (Unpublished study received Apr 16, 

1982 under 359-662; prepared by Cannon Laboratories, Inc., submitted by RhonePoulenc Chemical Co., Monmouth Junction, N.J.; CDL: 070772-C) 

40977602 Manning, C. (1988) Asulam Technical: Acute Toxicity to the Water Flea (Daphnia 

magna) Under Flow-Through Conditions: Proj. ID ESE No. 89325-0200-2130. 

Unpublished study prepared by Hunter/ ESE, Inc. 73 p. 

72-3 Acute Toxicity to Estuarine/Marine Organisms 

MRID Citation Reference 

98508 Vilkas, A.G.; Schneider, C.E. (1979) The Acute Toxicity of Asulam Technical to the 

Grass Shrimp, Palaemonetes pugio: UCES Project No. 11506-48-05. (Unpublished 

study received Apr 16, 1982 under 359-662; prepared by Union Carbide Corp., 

submitted by Rhone-Poulenc Chemical Co., Monmouth Junction, N.J.; CDL: 070772-D) 

98509 Schneider, C. (1979) The Acute Toxicity of Asulam Technical to the Fiddler Crab Uca 

pugilator: UCES Project No. 11506-48-04. (Unpublished study received Apr 16, 1982 

under 359-662; prepared by Union Carbide Corp., submitted by Rhone-Poulenc 

Chemical Co., Monmouth Junction, N.J.; CDL:070772-E) 

41000701 Manning, C. (1989) Asulam Technical: Acute Effect to New Shell Growth of the Eastern 

Oyster (Crassostrea virginica) Under Flow- through Conditions: Proj. ID 89325-0300-

2130. Unpublished study prepared by Hunter/ESE. 94 p. 

 

123-1 Seed germination/seedling emergence and vegitative vigor 

MRID Citation Reference 

42613801 Christensen, K. (1992) Asulam Sodium--Determination of Effects on 

Seed Germination, Seedling Emergence and Vegetative Vigor of Ten 

Plant Species: Final Report: Lab Project Number: 92-9-4431: 

10566.0292.6217.610. Unpublished study prepared by Springborn 

Labs., Inc. 214 p. 

43844601 Hoberg, J. (1995) Asulam Sodium--Determination of Effects on Seed 

Germination and Vegetative Vigor of Several Plant Species: 

Supplement to Final Report: Lab Project Number: 95-3-5751: 

10566.0292.6217.610. Unpublished study prepared by Springborn 

Labs, Inc. 94 p. 
-33 of 43-

123-2 Aquatic plant growth 

MRID Citation Reference 

42560301 Hoberg, J. (1992) Asulam Sodium--Toxicity to the Freshwater Green 

Alga, Selenastrum capricornutum: Final Report: Lab Project Number: 

92-8-4391: 10566.0292.6220.430. Unpublished study prepared by 

Springborn Labs, Inc. 61 p. 

42560302 Hoberg, J. (1992) Asulam Sodium--Toxicity to the Marine Diatom, 

Skeletonema costatum: Final Report: Lab Project Number: 92-8-4395: 

10566.0292.6221.450. Unpublished study prepared by Springborn 

Labs, Inc. 59 p. 

42611701 Hoberg, J. (1992) Asulam Sodium--Toxicity to the Duckweed Lemna 

gibba: Final Report: Lab Project Number: 92-9-4397: 

10566.0292.6222.410. Unpublished study prepared by Springborn 

Labs, Inc. 64 p. 

42613802 Hoberg, J. (1992) Asulam Sodium--Toxicity to the Freshwater Alga, 

Anabaena flos-aquae: Final Report: Lab Project Number: 92-10-4457: 

10566.0292.6218.420. Unpublished study prepared by Springborn Lab., 

Inc. 60 p. 

42631301 Hoberg, J. (1992) Asulam Sodium--Toxicity to the Freshwater Diatom, 

Navicula pelliculosa: Final Report: Lab Project Number: 92-12-4519: 

10566.0292.6219.440. Unpublished study prepared by Springborn 

Labs, Inc. 60 p. 
-34 of 43-

APPENDIX A. Data Call-in Tables 

Study Title: Aerobic soil metabolism

Guideline Number: 835.4100 

Study Substance: Na-asulam 

Rationale for Requiring the Data 

Per 40 CFR part 158, promulgated July 1, 2009, requires aerobic soil metabolism data for pesticide food and nonfood 

terrestrial uses. Currently the Agency has received one supplemental study on three soil types (MRID 41767801). An 

acceptable soil is required per OCSPP guideline 835.4100. Aerobic soil metabolism studies facilitate an understanding 

of a compound’s degradation in the soil under aerobic conditions in the laboratory. Depending on how quickly, to 

what extent, and to which transformation products the compound degrades, Na-asulam may or may not pose potential 

exposure concern. Previous studies indicated that freezing storage can affect residue characterization. Additional data 

is needed to support the registrant’s claim that sample processing occurred immediately following sampling. 

Practical Utility of the Data 

How will the data be used? 

Additional aerobic soil metabolism data will facilitate a better understanding of the fate of Na-asulam residues in soil, 

in order to characterize the variability in the degradation of Na-asulam in different soil types. If data indicate that 

degradation in aerobic soil occurs rapidly and produces nontoxic transformation products, then the Agency could 

potentially determine that Na-asulam residues of concern do not persist in soil under aerobic conditions. If data 

indicate that degradation is not appreciable in soil or that the transformation products are of similar or higher toxicity 

than the parent compound, then the Agency could conclude that Na-asulam residues of concern persist in soil under 

some aerobic conditions. 

How could the data impact the Agency’s future decision-making? 

If the required data indicate that Na-asulam in aerobic soils is rapidly biodegraded to nontoxic transformation 

products, then risk assessment conclusions and associated labeled use precautions and/or restrictions could be made 

less restrictive. 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 Na-asulam which are unnecessarily severe. 

Study Title: Aerobic aquatic metabolism

Guideline Number: 835.4300 

Study Substance: Na-asulam 

Rationale for Requiring the Data 

Per 40 CFR part 158, which was promulgated on July 1, 2009, states an aerobic aquatic metabolism study is required 

due to Na-asulam being applied to terrestrial crops. Two sediment: water systems are required per the guideline, 

currently one supplemental system has been submitted. Aerobic aquatic metabolism studies facilitate an understanding 

of a compound’s degradation in the water column or sediment under aerobic (oxygen-rich) conditions in the 

laboratory. These studies are generated by pesticide interaction with microorganisms in a water/sediment system. 

Depending on how quickly, to what extent, and to which transformation products the compound degrades, Na-asulam 

may or may not pose potential exposure concern in water. Because Na-asulam degradation in water is not well 

understood, the Agency is requiring data. Previous studies indicated that freezing storage can affect residue 

characterization. Additional data is needed to support the registrant’s claim that sample processing occurred 

immediately following sampling. 

Practical Utility of the Data 

How will the data be used? 

Aerobic aquatic metabolism data will facilitate a better understanding of the fate of Na-asulam residues in water. If 

data indicate that degradation in aerobic conditions occurs rapidly in water and produces nontoxic transformation 

products, then the Agency could potentially determine that Na-asulam residues of concern do not persist in water 

under aerobic conditions. If data indicate that degradation is not appreciable in water or that the transformation 

products are of similar or higher toxicity than the parent compound, then the Agency could conclude that Na-asulam 

residues of concern persist in water under aerobic conditions. 

How could the data impact the Agency’s future decision-making? 
-35 of 43-

In absence of these data, conservative assumptions will be made (3x the single value), Therefore, potential for risk to 

aquatic organisms may be overestimated and the use of Na-asulam might need to be restricted in areas where 

endangered species could be exposed. 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 Na-asulam which are 

unnecessarily severe. 

Study Title: Anaerobic Aquatic Metabolism 

Guideline Number: 835.4400 

Study Substance: Na-asulam 

Rationale for Requiring the Data 

Acceptable data have not been provided to quantify the metabolism of Na-asulam under anaerobic aquatic conditions; 

supplemental data has been submitted. According to 40 CFR Part 158 Subpart N, July, 2009 (data requirements for 

pesticides) anaerobic aquatic metabolism in two water:sediment systems are required for pesticides with terrestrial or 

aquatic food and nonfood uses. Since Na-asulam uses are classified as terrestrial, anaerobic aquatic metabolism data 

for Na-asulam should be submitted to fulfill OCSPP Guideline 835.4400. Previous studies indicated that freezing 

storage can affect residue characterization. Additional data is needed to support the registrant’s claim that sample 

processing occurred immediately following sampling. 

Practical Utility of the Data 

How will the data be used? 

Currently there are no acceptable anaerobic aquatic metabolism studies that track the formation and decline of Naasulam and its degradates. The submitted data will be used to characterize and quantify the environmental fate of Naasulam and its degradates in aquatic environments. For quantitative exposure estimation, these data will be used to 

confirm the conceptual model of Na-asulam fate and transport in aquatic environments. 

How could the data impact the Agency’s future decision-making? 

Without these required data, the fate of Na-asulam cannot be fully characterized and exposure to potentially toxic 

degradates cannot be quantified. The persistence of asulam and its degradates to which terrestrial and aquatic 

organisms will be exposed to is uncertain. In the absence of acceptable data, conservative assumptions will be made 

regarding the potential for formation of Na-asulam degradates. Therefore, potential for risk to aquatic organisms may 

be overestimated and the use of Na-asulam might need to be restricted in areas where endangered species could be 

exposed. 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 Na-asulam which are unnecessarily severe. 

Study Title: Terrestrial Field Dissipation 

Guideline Number: 835.6100 

Study Substance: Na-asulam 

Rationale for Requiring the Data 

The Agency has not received an acceptable terrestrial field dissipation study for Na-asulam, examining current use 

rates. Pursuant to 40 CFR part 158, Subpart N, terrestrial field dissipation studies (OCSPP guideline 835.6100) are 

required for all terrestrial food and nonfood pesticide uses. Field dissipation studies are the only means by which 

laboratory generated data used in models can be validated. Significant departures from field estimated and laboratory 

estimated half-lives can indicate weaknesses in data and mischaracterizations of physical-chemical properties. EFED 

recommends that a terrestrial field dissipation study be conducted for the representative use areas for Na-asulam. 

Practical Utility of the Data 

How will the data be used? 

No terrestrial field dissipation study that adequately tracks the formation and decline of Na-asulam and its degradates 

is currently available and the additional data will be used to characterize the environmental fate of Na-asulam. For 

quantitative exposure estimation, these data will be used to confirm the conceptual model of Na-asulam fate and 

transport in the environment. 

How could the data impact the Agency’s future decision-making? 

Without these required data, the fate of Na-asulam cannot be fully characterized and exposure to potentially toxic 

degradates cannot be quantified. The persistence of Na-asulam and degradates to which terrestrial and aquatic 
-36 of 43-

organisms will be exposed to is uncertain. In the absence of acceptable data, conservative assumptions will be made 

regarding the potential for formation of Na-asulam degradates. The lack of these data will limit the flexibility the 

Agency and registrants have complying with the Endangered Species Act and could result in use restrictions for Naasulam which are unnecessarily severe. 

Guideline Number: 835.6100 

Study Title: Frozen Storage Stability 

Study Substance: Na-asulam 

Rationale for Requiring the Data 

The Agency has a limited understanding of how Na-asulam behaves in frozen storage conditions between the time of 

sampling and the time of analysis. Previous studies have indicated that storage under frozen conditions results in 

some amount of material loss between sampling and the time of analysis. Submission of a storage stability study is 

essential in order to be confident that any degradation measured in the test system was due solely to the environment 

of that test system, and not due to handling and storage. 

Practical Utility of the Data 

How will the data be used? 

Storage stability data will facilitate a better understanding of the fate of Na-asulam residues during storage and 

handling between sampling and analysis. If data indicate that degradation of Na-asulam or its degradates occur then 

the data from the field studies are no longer valid as it would not be feasible to determine if the degradation measured 

in the test system was due solely to the environment of that test system, and not due to handling and storage. 

How could the data change the Agency’s decision or impact the Agency’s future decision-making? 

In the absence of the required data, the field data, as well as much of the laboratory data for Na-asulam will be 

qualitatively used in the risk assessment. These data are used for confirmatory data to ensure that any degradation 

observed in the test systems is due solely to the test environment and not handling or storage. 

Study Title: Analytical Methods (and Associated Independent Laboratory Validations) for Residues in Water, 

Sediment, and Soil 

Guideline Number: 835.6100 

Study Substance: Na-asulam 

Rationale for Requiring the Data 

Independently validated analytical methods for residues in water, sediment, and soil (environmental chemistry 

methods) submitted by the registrant are used to evaluate analyses described in submitted environmental fate and 

ecological effects studies. Submitted analytical methods are also used by various Federal, State, Tribal, and local 

agencies to detect and monitor residues that are or are suspected to be in environmental compartments due to outdoor 

uses and accidental releases. Independent laboratory validations for submitted analytical methods are necessary to 

confirm that the methods are functional and to confirm the levels of detection and quantitation reported in registrantprepared validations. 

Use of Na-asulam may impact surface water quality due to runoff of rain water and drift of residues. This is 

especially true for poorly draining soils, erodible soils, and soils with shallow ground water. Na-asulam has a 

potential for reaching both surface water and aquatic sediment via runoff, it also has similar characteristics to 

chemicals detected in ground water. Therefore, outside agencies may request analytical methods with which to 

monitor for Na-asulam residues in water and in soil or sediment. 

Practical Utility of the Data 

How will the data be used? 

In the absence of independently validated environmental chemistry methods, submitted environmental fate and 

ecological effects data may not be reviewable and entities outside the Agency may lack chemical-specific methods for 

analyses in environmental compartments. Independently validated environmental chemistry methods will be used to 

evaluate any newly submitted environmental fate and ecological effects data and will be made available for 

enforcement and monitoring purposes at the federal, state, and local levels. 

How could the data impact the Agency’s future decision-making? 
-37 of 43-

Without these required data, the fate of Na-asulam cannot be fully characterized and exposure to potentially toxic 

degradates cannot be quantified. The persistence of Na-asulam and potential degradates to which terrestrial and 

aquatic organisms will be exposed to is uncertain. In the absence of acceptable data, conservative assumptions will be 

made regarding the potential for formation of Na-asulam degradates. Therefore, potential for risk to aquatic 

organisms may be overestimated and the use of Na-asulam might need to be restricted in areas where endangered 

species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming 

into compliance with the Endangered Species Act and could result in use restrictions for Na-asulam which are 

unnecessarily severe. 

Guideline Number: 850.2100 

Study Title: Avian Acute Oral Toxicity Test 

Rationale for Requiring the Data 

Supplemental acute avian oral toxicity data for asulam were submitted for several species of birds; however, data are 

not available for a passerine species, which is now required under the 40 CFR Part 158 (CFR 40 2007) data 

requirements for conventional pesticides. The Part 158 data requirements specify that acute avian oral toxicity data be 

submitted for either mallard duck or bobwhite quail and a passerine species. Therefore, an avian oral toxicity test is 

required for passerine birds, as specified in 40 CFR Part 158. A passerine study protocol must be submitted for 

review by the Agency prior to initiation of this study. 

Practical Utility of the Data 

How will the data be used? 

Acute avian oral toxicity data for passerine species will be used to refine the screening-level assessment by 

determining whether there are differences in avian species sensitivity to asulam between passerines and species of 

other orders. If oral acute toxicity data are not submitted for passerines, risk will be assumed for all passerine species. 

How could the data impact the Agency’s future decision-making? 

If future endangered species risk assessments are performed without these data, the Agency would have to assume that 

asulam “may affect” listed birds directly (and listed species from other taxa indirectly), and use of asulam and its 

formulated products may need to be restricted in areas where listed species could be exposed. The lack of these data 

will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act 

and could result in use restrictions for asulam use that are unnecessarily severe. 

Guideline Number: 850.4225, 4250 

Study Title: Terrestrial Plant Toxicity Test 

Rationale for Requiring the Data 

Data regarding the toxicity of formulated sodium asulam to terrestrial plants are unavailable and required under 

40CFR Part 158. Data on technical grade sodium asulam indicates effects to terrestrial plant species two orders of 

magnitude below the maximum label rates, and formulated product is expected to be more toxic than TGAI 

Practical Utility of the Data 

How will the data be used? 

Vegetative vigor and seedling emergence data for terrestrial plants will be used to determine the spatial extent to 

which sodium asulam will affect non-target plant species in terrestrial environments. Additionally, these data will be 

used to determine the spatial extent of indirect effects to listed taxa. 

How could the data impact the Agency’s future decision-making? 

If future endangered species risk assessments are performed without these data, the Agency may have to employ 

conservative assumptions regarding the toxicity of formulated product. Therefore, use of sodium asulam and its 

formulated products may need to be restricted in areas where listed species could be exposed. The lack of these data 

will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act 

and could result in use restrictions for sodium asulam that are unnecessarily severe. 

Guideline Number: 850.2300 

Study Title: Avian Reproduction 

Rationale for Requiring the Data 
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Avian reproduction toxicity data are not available for the assessment of chronic exposure of birds to sodium asulam; 

these data are required under the 40 CFR Part 158 for pesticides with outdoor uses. These data are necessary to 

determine the reproductive toxicity of sodium asulam to avian species from chronic exposure. 

Practical Utility of the Data 

How will the data be used? 

Avian reproduction toxicity data for mallard ducks will be used in the screening-level assessment to determine 

whether there are effects on birds from chronic exposure to sodium asulam. If reproductive toxicity data are not 

submitted, risk will be assumed for all avian species. 

How could the data impact the Agency’s future decision-making? 

If future endangered species risk assessments are performed without these data, the Agency would have to assume that 

sodium asulam “may affect” listed birds directly (and listed species from other taxa indirectly), and use of sodium 

asulam products may need to be restricted in areas where listed species could be exposed. The lack of these data will 

limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and 

could result in use restrictions for isoxaben use that are unnecessarily severe. 

Guideline Number: 850.1350, 1400 

Study Title: Aquatic Invertebrate Life Cycle and Fish Early Life Stage 

Rationale for Requiring the Data 

Chronic invertebrate life cycle and chronic fish data are required under 40 CFR Part 158 data requirements for 

pesticides with outdoor uses. These data are necessary to determine if chronic exposure to isoxaben may adversely 

affect the survival, growth or reproduction of aquatic species. 

Practical Utility of the Data 

How will the data be used? 

These data are necessary to characterize the potential risks from sodium asulam to aquatic animals. Chronic exposure 

data will be used in the screening-level risk assessment to estimate the scope of sublethal effects and potential chronic 

risks to fish and aquatic invertebrates from the uses of sodium asulam. In the absence of these data, the Agency will 

presume risk to these taxa from chronic exposure to sodium asulam. 

How could the data change the Agency’s decision or impact the Agency’s future decision-making? 

If future endangered species risk assessments are performed without these data, the Agency would have to assume that 

sodium asulam “may affect” listed species directly (and listed species from other taxa indirectly), and use of sodium 

asulam products may need to be restricted in areas where listed species could be exposed. The lack of these data will 

limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and 

could result in use restrictions for sodium asulam use that are unnecessarily severe. 
-39 of 43-

Appendix B Summary of available effects studies 

All endpoints are reported in terms of asulam acid except terrestrial plants, which are reported in 

terms of sodium asulam. 

I. Aquatic Organisms 

Some aquatic toxicity studies were conducted with co-solvents. Given the solubility of asulam 

in water, it is unclear why solvents were used in these studies; however, the use of the solvents 

did not appear to impact the study results. 

Freshwater fish 

An acceptable 96-hr acute toxicity study with the rainbow trout (Oncorhynchus mykiss) is 

available for asulam (MRID 40872001). The fish were exposed to mean-measured 

concentrations of 0 (control), 20, 37.5, 61, 100 and 175 mg ae/L. No effects were reported at any 

concentration and the LC50 is reported to be >175 mg ae/L. 

An acceptable study with bluegill sunfish (Lepomis macrochirus; MRID 00098505) is available 

for asulam. Bluegill were exposed to mean-measured concentrations of 0 (negative and solvent 

controls), 18, 32, 56, 100 and 180 mg ae/L. Dimethylformamide (DMF) was used as a solvent. 

No effects were reported at any concentration and the LC50 is reported to be >180 mg ae/L. 

As a result of these studies, asulam is classified as practically nontoxic to freshwater fish on an 

acute exposure basis. 

Supplemental data are available for the toxicity of formulated asulam to fish (MRID 00054621). 

Rainbow trout, bluegill, goldfish (Carassius auratus) and channel catfish (Ictalurus punctatus) 

were exposed to concentrations of 0 (control) 648, 1080, 1800, 3000 and 5000 mg ae/L. No 

mortalities were reported for any species at any concentration, therefore the LC50 for each of the 

species was reported as >5000 mg ae/L. 

Freshwater invertebrates 

An acceptable 48-hr acute study with the freshwater invertebrate Daphnia magna is available for 

asulam (MRID 40977602). Twenty daphnids per level were exposed at mean measured 

concentrations of 0 (negative control), 9.3, 17.5, 25.5, 48.5 and 83 mg ae/L. Immobility was 0, 

0, 0, 0, 45 and 55% respectively. The EC50 for this study was found to be 67 mg ae/L with a 

probit slope of 4.1. 
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A second acceptable study (MRID 00098507) exposed daphnids at measured concentrations of 0 

(negative and solvent controls), 10, 20, 32, 56, 80, 96 and 110 mg ae/L. Acetone was used as a 

solvent. Immobility ranged from 25% at 10 mg ae/L to 100% at 110 mg ae/L, with an EC50

determined to be 27.1 mg ae/L with a probit slope of 2.2. 

Based on these studies, asulam is classified as slightly toxic to freshwater invertebrates on an 

acute exposure basis. 

Estuarine/marine fish 

There are no data assessing the effect of asulam on estuarine/marine fish 

Estuarine/marine invertebrates 

An acceptable study with asulam (97%) was conducted on the estuarine/marine grass shrimp 

(Palaemonetes pugio; MRID 00098508) at nominal concentrations of 0 (negative and solvent 

controls), 10, 18, 32, 56 and 100 mg ae/L. Acetone was used as solvent, but appeared to have no 

effect on the results. No effects were reported at any of the test concentrations and the LC50 was 

determined to be >100 mg ae/L. 

An acceptable study with fiddler crab (Uca pugilator; MRID 00098509) was conducted at 

nominal technical asulam (97%) concentrations of 0 (negative and solvent controls), 10, 18, 32, 

56 and 100 mg ae/L. Acetone was used as solvent. No effects were reported at any of the test 

concentrations and the LC50 was determined to be >100 mg ae/L. 

Based on these studies, asulam is classified as practically nontoxic to estuarine/marine 

invertebrates on an acute exposure basis. 

A supplemental study assessing the effect of asulam on the shell growth growth of Eastern oyster 

(Crassostrea virginica MRID 41000701) is available. Oysters were exposed to mean measured 

concentrations of 0 (control), 21.5, 40, 64.5, 105 and 185 mg ae/L. No effects were seen at any 

concentration; therefore the EC50 is determined to be >185 mg ae/L and the NOAEC is 185 mg 

ae/L. 

Plants 

 

One guideline study (MRID 42611701; Acceptable) is available assessing the toxicity of asulam 

to the aquatic vascular plant duckweed (Lemna gibba). Duckweed was exposed to initial 

measured concentrations of asulam of 0 (control) 0.035, 0.065, 0.12, 0.26 and 0.44 mg ae/L. The 

14-day EC50, based on frond number, is 0.14 mg ae/L and the NOAEC is 0.07 mg ae/L. 

Four guideline studies are available assessing the toxicity of asulam to aquatic nonvascular 

plants. The green algae Pseudokirchneriella subcapitata (formerly known as Selanastrum 

capricornutum) was exposed to mean-measured concentrations of asulam of 0(control) 0.02, 

0.049, 0.12, 0.29, 0.71 and 1.9 mg ae/L. The 96-hour EC50, based on cell density, is 0.18 mg 

ae/L and the NOAEC is 0.02 mg ae/L (MRID 42560301; Acceptable). 
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The cyanobacteria Anabaena flos aqua (MRID 42613802; Acceptable) was exposed to meanmeasured concentrations of asulam of 0(control) 0.023, 0.045, 0.089, 0.19, 0.37 and 0.72 mg 

ae/L. The 96-hour EC50, based on cell density, is 0.70 mg ae/L and the NOAEC is 0.09 mg ae/L. 

The diatom Skeletonema costatum (MRID 42560302; Acceptable) was exposed to meanmeasured concentrations of asulam of 0(control) 0.022, 0.058, 0.13, 0.33, 0.74 and 1.8 mg ae/L. 

The 96-hour EC50, based on cell density, is 0.44 mg ae/L and the NOAEC is 0.02 mg ae/L. 

The diatom Navicula pellicosa (MRID 42631301; Acceptable) was exposed to mean-measured 

concentrations of asulam of 0(control) 0.15, 0.30, 0.54, 1.3, 2.1 and 4.4 mg ae/L. The 96-hour 

EC50, based on cell density, is 2.3 mg ae/L and the NOAEC is 0.15 mg ae/L. 

II. Terrestrial Organisms 

Avian 

There are no guideline avian acute oral or subacute dietary toxicity studies for asulam. 

The acute oral toxicity of formulated asulam (40%) was studied in several avian species (MRID 

00056417; Supplemental). Partridge (Perdix perdix), mallard duck (Anas platyrhynchos), 

pheasant (Phasianus colchicus) and pigeons (Columba livia) were exposed to formulated asulam 

at doses of 0 (control), 1600, 2600 and 4000 mg ae/kg-bw. One mallard mortality was reported 

at the 4000 mg ae/kg-bw dose, but no other effects were observed. No mortalities or other 

effects were reported for pheasant or pigeons. Seven partridge mortalities were reported at 4000 

mg ae/kg-bw, and one mortality in both of the other doses and the control. The LD50 for birds, 

based on the partridge, is 3674.5 mg ae/kg-bw. Asulam is classified as practically nontoxic to 

avian species on an acute oral exposure basis. 

The 5-day subacute dietary toxicity of formulated asulam (60%) was studied in mallard 

ducklings (MRID 00056418; Supplemental). There were two parts to the mallard study, one 

testing up 75000 mg ae/kg-diet and another testing up to 100000 mg ae/kg-bw. Ten ducklings (7 

days old) per level were exposed to nominal concentrations of 0 (control), 10000, 15000, 22500, 

33750, 50000, 75000 and 100000 mg ae/kg-diet. There was a single control mortality in part one 

of the study and two mortalities (on different days) at the 75000 mg ae/kg-diet concentration in 

the second part. The LC50 for the study is >75000 mg ae/kg-diet. No other effects were 

reported. Studies with DDT were concurrently conducted but had no impact on the inferences 

drawn from the asulam study. 

The 5-day subacute dietary toxicity of formulated asulam (60%) was studied in pheasant chicks 

(MRID 00056419; Supplemental). In two studies, ten pheasants (7 day old) per level were 

exposed to nominal concentrations of 0 (control), 10000, 15000, 22500, 33750, 50000 and 75000 

mg ae/kg-diet. No mortalities or sublethal effects were reported at any concentration in either 

study. Based on these data, the LC50 is greater than 75000 mg/kg. Therefore, asulam is 

classified as practically nontoxic to birds on a subacute dietary basis. Studies with DDT were 

concurrently conducted but had no impact on the inferences drawn from the asulam study. 
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Mammals 

Mammal toxicity data are drawn from the Health Effects Division (HED) chapter in support of 

the RED. The data are summarized below. 

Acute 

Toxicity testing with the TGAI (88% asulam) produced an acute oral LD50 >5000 mg ae/kg-bw. 

Based on these data, asulam is classified as practically nontoxic to mammals on an acute 

exposure basis (MRID 42110001, 40960501). 

Chronic Toxicity 

A two-generation rat reproduction study (MRID 00098540) was conducted at nominal 

concentrations of 0 (control), 1000, 5000, and 25000 mg ae/kg-diet and produced a NOAEL of 

1000 mg ae/kg-diet (50 mg ae/kg-bw/day). The LOAEL was 5000 ppm based on reduction in 

number of live births per litter. Other effects in the study included decreased body and organ 

weight in the parents at 25000 mg ae/kg-diet concentration. 

Terrestrial Invertebrates 

 

An acute contact study with young adult honeybees (Apis mellifera; MRID 00018842) reports 

4.9% mortality at 36.26 μg ae/bee after 96 hours, which indicates asulam is practically nontoxic 

to honeybees. However, there are no data associated with the study, which is an investigation 

into multiple pesticides. 

 Plants 

The toxicity of asulam sodium to terrestrial plant seedling emergence and vegetative vigor was 

assessed in separate studies reported under MRID 42613801 (Supplemental). The studies were 

conducted with technical asulam sodium rather than typical end use product as required under 40 

CFR Part 158. Herbicidal active ingredients are usually formulated with adjuvants or surfactants 

that enhance the activity of the pesticide. Therefore, the sensitivity of terrestrial plants to asulam 

may be underestimated. 

 For seedling emergence, cabbage (Brassica oleracea) and oat (Avena sativa) were tested at 

measured concentrations of 0 (control), 0.099, 0.19, 0.40, 0.73, 1.7 lbs ai/A, corn (Zea mays), 

cucumber (Cucumis sativus), soybean (Glycine max) and tomato (Solanum lycopersicum) were 

tested at measured concentrations of 0 (control), 0.40, 0.73, 1.7, 3.0 and 6.6 lbs ai/A. Onion 

(Allium cepa) was tested at measured concentrations of 0 (control), 0.19, 0.40, 0.73, 1.7, 3.0 lbs 

ai/A, ryegrass (Lolium perenne) at 0 (control), 0.050, 0.099, 0.19, 0.40, 0.73 lbs ai/A, radish 

(Raphanus sativus) at 0 (control), 0.050, 0.099, 0.19, 0.40, 0.73, 1.7 lbs ai/A. Lettuce (Lactuca 

sativa) was tested at measured concentrations of 0 (control), 0.023, 0.049, 0.010, 0.20, 0.41 and 

0.83 lb ai/A. 
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Biomass (dry weight), a preferred parameter, was not measured in the seedling emergence test. 

Of the parameters reported, shoot length was the most sensitive for all species. Lettuce was the 

most sensitive dicot with an EC25 of 0.084 lbs ai/A. Due to the low number of replicates (three) 

and high degree of variability, the power of the study was insufficient to determine a valid 

NOAEC; therefore, the EC05, 0.026 lbs ai/A, will be used for listed species assessment. 

Ryegrass was the most sensitive monocot, with an EC25 of 0.17 lbs ai/A and a NOAEC of 0.099 

lbs ai/A. 

For vegetative vigor corn was tested at a single rate of 6.6 lbs ai/A, cabbage and tomato were 

tested at measured concentrations of 0 (control), 0.19, 0.38, 0.78, 1.5 and 3.0 lbs ai/A, cucumber 

was tested at 0 (control), 0.20, 0.41, 0.82, 1.7 and 3.3 lbs ai/A, lettuce was tested at was tested at 

0 (control), 0.044, 0.097, 0.20, 0.41 and 0.82 lbs ai/A. Oat, soybean and ryegrass were tested at 

measured concentrations of 0 (control), 0.38, 0.78, 1.5, 3.0, and 6.2 lbs ai/A. Onion was tested at 

measured concentrations of 0 (control), 0.41, 0.82, 1.7, 3.3 and 6.6 lbs ai/A, and radish was 

tested at measured concentrations of 0 (control), 0.097, 0.20, 0.41, 0.82 and 1.7 lbs ai/A. Effects 

were observed at all concentrations for several species, but the data were inadequate to calculate 

endpoints. Lettuce was the most sensitive dicot with an EC25 of 0.085 and a NOAEC of 0.044 

lbs ai/A. 

Though supplemental data are available from the study, a continuation study (MRID 43844601; 

Supplemental) was conducted to clarify the endpoints for purposes of risk assessment. The 

continuation study was conducted on corn, onion cabbage and cucumber and definitive endpoints 

determined, except for an onion NOAEC. This study confirmed that lettuce was the most 

sensitive dicot as determined in the previous study. Onion was determined to be the most 

sensitive monocot with an EC25 of 0.27 lbs ai/A based on shoot weight. When a statistically 

determined NOAEC is greater than the calculated EC25, as is the case with onion in this study, 

the EC05 is used for listed species assessment. The EC05 for onion shoot weight is 0.042 lbs ai/A.