UNITED STATES ENVIRONMENTAI. PROTECTION

AGENCY

WASHINGTON D.C., 20460

OFFICE OF

PREVENTION, PESTICIDES AND

TOX IC SUBSTANCES

PC Code: 176603

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MEMORANDUM

DATE:

SUBJECT:

FROM:

TO :

October 4,2010

Section 3 Request for Zonastat, a New Chemical Proposed for Use to Control

Wild Horses and Burros

Nancy Andrews, Chief fJYYJ gi tJcj:M/o

Edward Odenkirchen, Senior Ad ~(f-!VJ:. (jJ Ue O/f{/ O

Sujatha Sankula, Lead Biologist ."'"\?'7J 7

Brian Anderson, Biologist t -.r. I 7 {j'

Environmental Risk Branch llEFED (7507P)

John Hebert, Product Manager

Insecticide Rodentici de Branch

Registration Division (7505P)

1. Summary of Proposed Action:

The Humane Society of the United States is applying for Section 3 registration for ZonaStat-H

(porcine Zona pellucida) to control feral and wild horses and burros. The active ingredient is

porcine Zona pellucida (PZP), which is an imrnunocontraceptive vaccine that is administered to

target animals via intramuscular injection (either by dart or by hand).

The application rate is 1.0 cc of PZP + adjuvant (modified Freund's complete adjuvant or

modified Freund's incomplete adjuvant). A second administration is given 2 to 4 weeks after the

initial priming dose then annually thereafter.

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This memorandum discusses the data requirements and qualitatively characterizes potential risks

to non-target organisms from the proposed use.

2. Status of Submitted Data

No studies have been submitted in support of this Section 3. Waivers were submitted to fulfill

required ecological effects and environmental fate guideline studies. Although the proposed use

could qualify as outdoor uses, there are no exposure routes to non-target plants or animals that

are likely to occur (see Section 3 of this document). Given the lack of potential exposures to

non-target organisms, the proposed use pattern is more consistent with an indoor use from a data

requirements perspective. For indoor uses, no studies are required. However, an acute oral

study in birds, acute studies in aquatic animals, and hydrolysis studies are conditionally required.

These studies are not considered to be necessary for the proposed uses for the following reasons:

• Acute oral studies in birds: Oral exposure could occur via consumption of treated

animals. However, the proposed active ingredient is a protein that is expected to be

denatured after oral consumption. This is evidenced by the lack of efficacy via oral

exposure (the active ingredient must be injected to target animals to be effective).

Therefore, acute oral toxicity studies are not being required at this time .

• Acu te studies in aquatic animals and hydro lysis: Potential for contamination of water

is limited . The active ingredient is not expected to be excreted intact from treated

animals. Therefore, exposure to aquatic systems is limited to entry of wayward darts. A

dart contains 100 ug of active ingredient (MRID 47859805). Therefore, even if the

contents of a dart were to enter a pond the size of EPA's standard ecological water body

of 20,000,000 L, the resulting concentration would be 0.005 ngIL.

Due to the limited possibility of exposure occurring to non-target aquatic or terrestrial

animals, no data are being required at this time for the proposed use.

3. . Potential Exposure and Risk to Non-Target Organisms

Given that the proposed administration route is by injection (either dart or hand) to the target

animal, potential exposure routes for non-target organisms resulting from labeled uses is

somewhat limited. Potential exposure pathways to non-target organisms could include

secondary exposure to carnivores, exposure to excreted material , and exposure from wayward

darts (accidental exposure). All of these exposure pathways, however, are considered unlikely to

result in potential risks to non-target organisms at levels of concern to the Agency as described

below .

Dietary exposure to Zonastat is not expected to result in adverse effects at levels of concern to

the Agency because it is a protein that is anticipated to be deactivated in the digestive tract, and

absorption from the Gl tract is expected to be limited. Also, excretion data indicates that the

short half-life in treated mammals suggests that the potential for secondary exposure is limited.

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Potential exposure to aquatic environments is expected to be limited to accidental exposures.

However, as previously discussed, even if a wayward dart were to enter a water body and all of

the Zonastat within the dart were to enter a water body, the resulting concentration would be

negligible (5x lO9 mgIL). Because the active ingredient is a protein, it would be expected to be

rapidly degraded in natural waters.

4. Threatened and Endangered Species Concern

4.1. Action Area

For listed species assessment purposes. the action area is considered to be the area affected

directl y or indirectly by the Federal action and not merel y the immediate area involved in the

action. At the initial screening-level, the risk assessment considers broadly described

taxonomic groups and so conservatively assumes that listed species within those broad

groups are co-located with the pesticide treatment area. This means that terrestrial plants and

wildlife are assumed to be located on or adjacent to the treated site and aquatic organisms are

assumed to be located in a surface water body adjacent to the treated site. The assessment

also assumes that listed species are located within an assumed area, which has the relatively

highest potential exposure to the pesticide, and that exposures are likely to decrease with

distance from the treatment area.

If the assumptions associated with the screening-level action area result in RQs that are

below the listed species LOCs, a "no effect" determination conclusion is made with respect

to listed species in that taxa, and no further refinement of the action area is necessary.

Furthermore, RQs below the listed species LOCs for a given taxonomic group indicate no

concern for indirect effects upon listed species that depend upon the taxonomic group

covered by the RQ as a resource. However, in situations where the screening assumptions

lead to RQs in excess of the listed species LOCs for a given taxonomic group, a potential for

a "may affect" conclusion exists and may be associated with direct effects on listed species

belonging to that taxonomic group or may extend to indirect effects upon listed species that

depend upon that taxonomic group as a resource. In such cases, additi onal information on

the biology of listed species, the locations of these species, and the locations of use sites

could be considered to determine the extent to which screening assumptions regarding an

action area apply to a particular listed organism. These subsequent refinement steps could

consider how this information would impact the action area for a particular listed organism

and may potentially include areas of exposure that are downwind and downstream of the

pesticide use site.

For this assessment, RQs were not calculated. However, use of Zonastat could result in the

following environmental effects:

1. Reduction in wild horseslburros;

2. Increased risk of death and morbidity resulting from allergic responses.

Thes e possible environmental effects could affect listed species by the following:

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• Reduction in wild horse populations could constitute an avenue for effects on listed

species by reducing prey base of listed species (negative effect);

• Reduction in wild horse populations could result in habitat responses that may

positively affect listed species due to reductions in overpopu lation;

• Increased presence of moribund animals that may occur via allergic responses could

result in increased carrion availability (i.e. food for condors, positive effect); .

4.2. Co-LocationAnalysis

To determine whether the proposed uses are geographically associated with known locations

of listed species, a screening-level search of the LOCATES (version 2.10.3) database is

typically conducted. The database compared county- level location data for listed species

with county-level crop production data (as available in the 2002 agricultural census) to

identify any coarse overlaps of listed species with the proposed labeled uses of Zonastat.

Listed species are those that are currently on the Federal list of endangered and threatened

wildlife and plants. However, for the current proposed registration for use of Zonastat on

wild horses and burros, there are no geographical limitations included on the labels, and

geographical limitations regarding where Zonastat may be used are uncertain. Therefore, it

is assumed that Zonastat may be used in any county in the United States for the screening

level analysis. For this reason, it is assumed that every federally listed species may be

affected by the proposed uses of Zonastat, and a LOCATES analysis was not conducted.

The LOCATES database identifies those U.S. counties that include non-crop and turf areas

and that have federally-listed endangered or threatened species that may be directly or

indirectly affected . The list of affected species derived from LOCATES was not included in

this assessment because the uses cover most of the United States and the direct and indirect

effects includes most species. With additional refinement by exploring more detailed use

patterns and species biology (e.g., geographic location, specific feeding habits, time of year

likely to utilize crop fields), some species listed may be determined to be not likely to be

affected.

4.3. Taxonomic Groups Potentially at Risk

A summary of the risk conclusions and direct and indirect effects determinations is presented

in Table 1. Because the proposed uses cannot be geographically limited, all federally listed

species are assumed to be potentially indirectly affected.

Table 1. Potential Listed Species Risks Associated wit h Direct or In direct Effects

Due to the Proposed Use of Zonastat!

Listed Taxonomy Direct Effects Indirect Effects

Terrestrial and semi-aquatic plants - No Yes monocots and dicots

Terrestrial invertebrates No Yes

Birds (surrogate for terrestrial-phase No Yes

amohibians and reotiles)

Mammals No Yes

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Table 1. Potential Listed Species Risks Associa ted with Direct or Indirect Effects

Due to the Proposed Use of Zonastat'

Listed Taxonomy Direct Effects Indirect Effects

Aquatic vascular olants No Yes

Aquatic non-va scular plants No Yes

Freshwater fish (surrogate for aquatic- No Yes [phase amphibians)

Freshwater Invertebrates No Yes

Freshwater Benthic Invertebrates No Yes

EstuarinelMarine Fish No Yes

Estuarine/Marine Crustaceans No Yes

EstuarinelMarine Mollusks No Yes

I. Effect on listed species may be negative or beneficial

5. Conclusions

The available data suggest that potential exposures to non-target animals is not expected to result

in any significant risk concerns to terrestrial or aquatic organisms from the proposed use.

However, indirect effects (potentially beneficial or negative) to Listed species could not be

precluded.

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