UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

PC CODE: 014901 & 000905 

DP BARCODE: D419790 

DATE: August 6, 2014 

MEMORANDUM 

SUBJECT: Preliminary Ecological Risk Assessment for the Registration Review of 

Yellow Mustard Seed (PC Code 014901) and Sodium Alpha Olefin 

FROM: Nicholas 

Sulfonate 

Mastrota

(PC Cod

, 

e 

Ph.D., 

000905)

Wildlife Biologist 

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James K. Wolf, Ph.D., Environmental Scientist /(.lJfr'O 

Environmental Risk Branch 3 

Environmental Fate and Effects Division (7507P) 

THROUGH: Dana Spatz, Branch Chie~~~ ~ .. C.- 2.,0l '-\ 

Environmental Risk Branch~ ------"'<~ ~ 

Environmental Fate and Effects Division (7507P) 

TO: Linda Arrington, Branch Chief 

Shirley Keel, Chemical Review Manager 

Risk Management and Implementation Branch 5 

Pesticide Re-Evaluation Division (7508P) 

This memorandum summarizes the potential ecological risk of two active ingredients, yellow 

mustard seed (PC Code 014901) and sodium Cl4-C16 alpha-olefin sulfonate (PC Code 000905, 

CAS 68439-57-6), that are formulated together in only one registered pesticide product in the 

United States; the rodenticide V ARGON (EPA Reg. No. 87972-1 ). In Canada, this same product 

is registered with the name EXIT. The product is used for control of the Richardson's ground 

squirrel (Urocitellus richardsonii) and the Wyoming ground squirrel (Urocitellus elegans). The 

product is injected under pressure, forming a foam, into a closed burrow system. Ground 

squirrels in the burrow are killed by asphyxiation. V ARGON contains 0.89% yellow mustard seed 

and 6.91% sodium alpha-olefin sulfonate. Neither of these ingredients are listed as active 

ingredients in any other pesticide product registered in the United States. 

The Environmental Fate and Effects Division completed an ecological risk and drinking water 

assessment for the Section 3 registration of these two active ingredients on December 12, 2002 

(D286494). The only ecological risk identified for this product was the chance that non-target 

animals may be impacted if they are present in the burrow at the time of treatment. There was 

particular concern noted for the western burrowing owl (Athene cunicularia hypogea), since this 

owl will nest in burrows dug by other animals. The burrowing owl is not listed as threatened or 

endangered in the United States. Based on recommendations made in this risk assessment, the 
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following precautionary label statement was added to mitigate risk to non-target animals which 

may be present in the burrow: 

“This product will suffocate all organisms within the treated burrow. Do not apply where 

there is evidence that the burrow may be occupied by species other than Richardson’s 

ground squirrels and Wyoming ground squirrels.” 

The risk assessment conducted in 2002 was qualitative, as the only hazard this product presents is 

from asphyxiation. Neither of the active ingredients are expected to have significant toxicity. 

Mustard seed is a natural product that is widely consumed as an ingredient in condiments 

(mustards) and as a spice (dry mustard). Sodium alpha-olefin sulfonate is a surfactant that is 

widely used as an ingredient in shampoos, soaps, and cosmetics. Little or no exposure is expected 

to occur to animals that are not in the burrows at the time of treatment. The assessment also notes 

this control method would not result in carcasses of ground squirrels with toxic tissue residues, 

and therefore would not pose any secondary poisoning risk to predatory animals. 

The previous assessment also concluded that surface and ground water exposure would be low 

based on environmental fate information and the use pattern. 

No changes in use pattern, science policy, or available data have occurred since the 2002 

assessment that would change the risk conclusions. In addition, no ecological incidents 

associated with either of these active ingredients have been reported to the EPA1

. Therefore, the 

2002 assessment can be relied upon for the Registration Review of yellow mustard seed (PC Code 

014901) and sodium C14-C16 alpha-olefin sulfonate (PC Code 000905). 

Effects on Threatened and Endangered Species 

In November 2013, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the National 

Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department of 

Agriculture (USDA) released a summary of their joint Interim Approaches for assessing risks to 

listed species from pesticides. The Interim Approaches were developed jointly by the agencies in 

response to the National Academy of Sciences’ (NAS) recommendations and reflect a common 

approach to risk assessment shared by the agencies as a way of addressing scientific differences 

between the EPA and the Services. The NAS report outlines recommendations on specific 

scientific and technical issues related to the development of pesticide risk assessments that EPA 

and the Services must conduct in connection with their obligations under the Endangered Species 

Act (ESA) and FIFRA. 

The joint Interim Approaches were released prior to a stakeholder workshop held on November 

15, 2013. In addition, the EPA presented the joint Interim Approaches at the December 2013 

Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues Research and Evaluation 

Group (SFIREG) meetings, and held a stakeholder workshop in April 2014, allowing additional 

opportunities for stakeholders to comment on the Interim Approaches. As part of a phased, 

iterative process for developing the Interim Approaches, the agencies will also consider public 

 

1

 The Ecological Incident Information System (EIIS) and the Aggregate Summary component of the Incident Data 

System (IDS) were queried on July 22, 2014. 
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comments on the Interim Approaches in connection with the development of upcoming 

Registration Review decisions. The details of the joint Interim Approaches are contained in the 

white paper “Interim Approaches for National-Level Pesticide Endangered Species Act 

Assessments Based on the Recommendations of the National Academy of Sciences April 2013 

Report,” dated November 1, 2013. 

Given that the agencies are continuing to develop and work toward implementation of the Interim 

Approaches to assess the potential risks of pesticides to listed species and their designated critical 

habitat, this preliminary risk assessment does not contain a complete ESA analysis that includes 

effects determinations for specific listed species or designated critical habitat. Although EPA has 

not yet completed effects determinations for specific species or habitats, for this preliminary 

assessment EPA conducted a screening-level assessment for all taxa of non-target wildlife and 

plants that assumes for the sake of the assessment that listed species and designated critical 

habitats may be present in the vicinity of the application. This screening level assessment will 

allow EPA to focus its future evaluations on the types of species where the potential for effects 

exists once the scientific methods being developed by the agencies have been fully vetted. Once 

the agencies have fully developed and implemented the scientific methods necessary to complete 

risk assessments for endangered and threatened (listed) species and their designated critical 

habitats, these methods will be applied to subsequent analyses for yellow mustard seed and 

sodium C14-C16 alpha-olefin sulfonate as part of completing this registration review.