Page 2 of 49 the Actellic® and Execute® labels to furthe r minimize the potential for exposure in the
environment.

For cattle eartag uses, risks of concern leading to adverse impacts are not identified for any aquatic or terrestrial taxa cons idering its usage limited to past ure use sites. The number of treated cattle anticipated at a pasture site, does not result in any risk within the terrestrial
environment about the treatment site or within nearby water bodies. Pirimiphos-methyl is not widely used at feedlots since infestati ons of its targeted pests, horn flies ( Haematobia irritans)
and face flies (Musca autumnalis ) are not anticipated at these use sites.Page 3 of 49 

# Preliminary Environmental Fate and Ecological RiskAssessment for the Registration Review of Pirimiphosmethyl

O-(2-Diethylamino-6-methylpyrimidin- 4-yl) O,O-dimethyl phosphorothioate

(Pirimiphos-methyl, CAS 029232-93-7)

P

repared by: Justin Housenger, Biologist Gabe Rothman., Environmental Scientist U. S. Environmental Protection Agency Office of Pesticide Programs

E nvironmental Fate and Effects Division

E nvironmental Risk Branch IV 1200 Pennsylvania Ave., NW

M

ail Code 7507P Washington, DC 20460 R eviewed by: Geoffrey Sinclair, Biologist José L. Meléndez, Chemist Mah Shamim, Branch ChiefPage 4 of 49 Table of Contents

1. Executive Summary ............................................................................................................. ... 5

2. Use Characterization .......................................................................................................... ..... 7
3. Exposure Characterization ..................................................................................................... . 8

3.1 Transport and Dissipation Pathways .............................................................................. 11

3.2 Degradation ................................................................................................................... . 11

3.3 Bioaccumulation ............................................................................................................. 1 2

3.4 Exposure Pathways ........................................................................................................ 12

3.5 Aquatic Exposure Analysis ............................................................................................ 15

3.6 Terrestrial Exposure Analysis ........................................................................................ 18

4. Ecological Effects Characterization ...................................................................................... 19

4.1 Aquatic Effects Summary .............................................................................................. 19

4.2 Terrestrial Effects Summary .......................................................................................... 20 4.3 Degradate toxicity .................................................................................................. ....... 22 4.4 ECOTOX Open Literature .............................................................................................. 2 3
4.5 Review of Incident Data ............................................................................................... .. 23
5. Risk Characterization ......................................................................................................... ... 24
5.1. Risk Estimation .............................................................................................................. 24
5.2. Risk Description ............................................................................................................. 26

6. Endocrine Disruptor Screening Program .............................................................................. 32

7. Federally Threatened and Endangered (Listed) Species of Concern .................................... 33

7.1 Action Area ................................................................................................................... . 34

7.2 Listed Species Occurrence Associated with Registered Uses ........................................ 35

8. Conclusions ................................................................................................................... ........ 35

9. References .................................................................................................................... ......... 36 Appendix A. Environmental Fate and Ecologi cal Effects Data for Pirimiphos-methyl .............. 38 Appendix B. Aquatic Exposure Modeling Summary .................................................................. 42 Appendix C. Inhalation Expos ure Screening Evaluation ............................................................ 44 Appendix D. Drinking Water Expos ure Screening Evaluation ................................................... 47 Appendix E. Degradates Summ ary for Pirimiphos-Methyl ......................................................... 48Page 5 of 49 

## 1. Executive Summary

This document contains the environmental fate a nd ecological risk assessments for the registered uses of the organophosphate chemical pirimiphos-methyl [O-(2-Diethylamino-6- methylpyrimidin-4-yl) O,O-di methyl phosphorothioate].

Pirimiphos-methyl was originally intr oduced in the United States in 1984 1 . There are a number of active Section 3 products containing pirimiphos-methyl that incl ude post-harvest treatment of corn or sorghum seeds and grain for immediate storage as well as treated ear tag products applied to beef and non-lactating da iry cattle or calves. Pirimiphos-met hyl ear tags ultimately result in residues being absorbed by the hide of cattle. Ther e are also two special local needs Section 24(c) labels. The Washington State labe l is for indoor fogger treatment on iris bulbs. Michigan labeled uses include dip and drench treatment to gladio la bulbs and indoor fogger treatment for gladiola bulbs. According to Office of Pesticide Program s Information Network (OPPIN), cancellation is pending for the Michigan label.

Post harvest Stored Grain Uses

For pirimiphos-methyl post harvest stored grain us es, it was previously c oncluded in the Problem Formulation (DP Barcode 362650, dated March 9, 2009) and reaffirmed in this assessment, that aquatic and terrestrial exposure resulting from the treated seed storage is limited considering the small application rate made to grain as well as the long interval betwee n time of treatment and planting of the treated seeds. Therefore, risks of concern are not expected for the post-harvest stored grain uses of pirimiphos-methyl. However, while the exposure scen ario associated with replanting treated seed is expected to be most prevalent, EFED recommends to address potential pirimiphos-methyl treatments to corn and sorghum grain stored at locati ons other than indoor storage bins, such as outdoor bunkers, on the Actel lic® and Execute® labels to further minimize the potential for exposure in the environment.

Eartag Uses

The conceptual model in this risk assessment iden tifies the main pot ential for exposure to aquatic organisms associated with pirimiphos-methyl eartags uses resulting from wash off of residues and subsequent runoff to aquatic environments from cattl e eartag applications. These applications are mainly expected to occur at pastureland use sites and not at feedlots (refer to the Use
Characterization Section in Section 2 for a further description). The main uncertainties that exist
for this scenario are the amount of cattle simultaneous ly treated with eartags at a given use site and the washoff fraction from cattle hide resulting fro m rainfall occurring concurrent with pirimiphosmethyl treatment. As a result of these uncertainties, risk quotients (RQs) were not estimated in this assessment as they woul d be in a deterministic fash ion for conventional uses ( i.e. foliar spray). Instead, this risk assessment addresses these uncertainties by utilizin g a bracketing approach exploring numbers of cattle treate d that would indicate a risk concern to aq uatic organisms over a range of washoff fractions to determine the leve l pirimiphos-methyl treatment causing a concern.

1 http://pmep.cce.cornell.edu/ profiles/insect-mite/mevinp hos-propargite/pirimiphos-met hyl/insect-prof-actellic.htmlPage 6 of 49 The screening aquatic exposure model, the GENeric Es timated Exposure Concentration model (GENEEC) is used as the basis of the bracketing analysis describe d above, to assess runoff from a generic 10-hectare treated use site to a 1-hectare pond. The Pesticide in Water Calculator (PWC), which is normally used to assess runoff of pes ticide residues for cropped fields, is not employed in this assessment given unique eartag treatm ent. The adverse impacts analysis initially incorporates the GENEEC estimated exposure co ncentration (EEC) in surface water normalized to one head of treated cattle. Then, available acute toxicity data for freshwater fish and freshwater invertebrates are incorporated to determine the number of head of treated cattle meeting and exceeding the levels of concern (LOCs) threshold for aquatic species. Additionally, the level of
washoff or washoff fraction to re sult in adverse impacts to aquatic taxa is determined. As is discussed and justified in Section 4.3 , the combined residues of parent pirimiphos-methyl along with the residues of O-2 diethylamino-6-me thylpyrimidin-4-yl o-methyl-phosphorothioate (hereafter referred to as degradat e No.2) will be considered the st ressor of concern for ecological risk assessment purposes. The final results wi th the bracketing analysis are presented in Table 9

.

The results with the number of heads of cattle caus ing concern at certain levels of washoff fractions of residues presented in Table 9 are put into perspective with the density of cattle at expected at potential pastureland use sites in Risk Description Section ( Section 5.2)

. In general, adverse impacts to aquatic organisms from washoff of residues from pirimiphos-methyl eartags are not expected considering that much of its use occurs at sites with sm all cattle inventories. While adverse impacts to listed aquatic invertebra tes may occur with 5 percent of residues from eartags washing off into water bodies at feedlot s ites keeping 40 head of ca ttle or less, it is not expected that this level of washoff would occur consider ing the expected reduction in environmental loading from factors such as its semi-volatile nature and propensity for delayed rainfall events during treatments not captured in this assessment. These uncertainties, discussed
further in Section 6 , provides further insights that a small por tion of residues (less than 5 percent) are likely to washoff and end up in water bodies nearby pirimiphos-methyl eartag use sites, and
therefore not result in risks of concern for aquatic orgnaisms.

It is worth noting that only acute freshwater fish and invertebrate toxicity data is available. However, given the toxicity that is established with organophosphate (OP) insecticides to aquatic taxa, similar effects and thresholds will be assumed for estuarine/marine fish and invertebrates when used in proximity to these environments. No data are available to characterize the chronic toxicity of pirimiphos-methyl to aquatic species. It is an uncertainty as to what level of washoff would be needed to yield effects to growth or reproduction on fish or a quatic invertebrates. Additionally, no data are available to character ize the subchronic and chronic toxicity of pirimiphos-methyl to sediment dwelling inverteb rates. Environmental fate data indicate pirimiphos-methyl has a propensity to partitio n to the sediment based on its range of K d values (15.6 – 161.9 mL/g) and moderately high log K OW value of 4.2.

Additionally, no data are available fo r vascular or non-vascul ar aquatic plants or terrestrial plants. Pirimiphos-methyl is highly toxic to adult honey bees on an acute contact a nd acute oral basis as would be anticipated from an organophosphorus (O P) insecticide. There are no data to
characterize the acute and chroni c oral toxicity to honey bee la rvae. Available data indicate pirimiphos-methyl is highly toxic to birds on an acute oral and subacute dietary basis, however, asPage 7 of 49 indicated previously, the extent as to the magnitude of residues this taxa as well as mammals would be exposed to is an uncertainty.

There are also more general uncer tainties as to the extent that terrestrial organisms would be exposed as a result of the cattle eartag use. Pirimiphos-methyl does show high levels of toxicity to birds on an acute oral and subacute dietary basis although toxicity is lower for mammals on an acute oral basis as compared to birds. The litera ture shows that some species of birds and mammals are not only present in feedlots 2 , but also may be responsible for th e spread of certain diseases in
cattle feedlots such as E. coli and Salmonella 3 . Because there are toxic effects to taxa confirmed to be present in pastureland use sites the esti mation of a dose or concentration that would be
available to these taxa is nece ssary but difficult with standard approaches. As pirimiphos-methyl does not have spray or granular uses, simulating exposure estimation with the Terrestrial Exposure Model (T-REX) is not feasible. Additionally, a ny exposure of pirimiphos-methyl to these taxa would likely originate from the eartags falling off of the cattle, a scenario that this assessment assumes is not frequent.



## 2. Use Characterization

In this document, only the most pertinent detail s regarding the Use Characterization are briefly
summarized below. Section 3.3 of the original problem formul ation document can be referred to
for further details.

Pirimiphos-methyl uses encompass six active regi strations. The labels by FIFRA classification
are summarized below:

 Four Section 3 labels, and

 Two Special Local Needs (Section 24c) labels

Uses for the Section 3 pirimiphos-methyl registrations include cattle eartag us es (for lactating and beef cattle) and post-harvest stored grain seed treatments for corn and sorghum seeds. Eartags contain up to 3.84 grams a.i. per animal (or 1.92 grams a.i. per eartag). For post-harvest seed treatments, up to 0.12 lbs a.i. per 1,000 square f eet of grain may be applied. There are no restrictions for where pirimiphos-methyl can be used nationwide.

2 Palmer, Thomas K. 1976. “Pest Bird Damage Control in Cattle Feedlots: The Integrated Systems Approach.” Proceeedings of the 7 th Pest Vertebrate Conference ,. Available online at:http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1035&context=vpc7&seiredir=1&referer=http%3A%2F%2Fscholar.google.com%2Fscholar%3Fhl%3Den%26as_sdt%3D0%2C9%26q%3D
birds%2Band%2Bmammals%2Bin%2Bcattle%2Bfeedlots#search=%22birds%20mammals%20cattle%20feedlots%

22

3 Gaukler, Shannon M et al. (2009). “Escherichia coli, Salmonella, and Mycobacterium avium subsp. Paratuberculosis in Wild European St arlings at a Kansas Cattle Feedlot.” Avian Diseases , 53(4):544-551. Available
online: http://lib.dr.iastate.edu/cgi/viewcontent. cgi?article=1040&context=vmpm_pubs&seiredir=1&referer=http%3A%2F%2Fscholar.google.com%2Fscholar%3Fq%3Dbirds%2Band%2Bmammals%2Bin% 2Bcattle%2Bfeedlots%2Band%2Be%2Bcoli%26btnG%3D%26hl%3Den%26as_sdt%3D0%252C9#search=%22bir
ds%20mammals%20cattle%20feedlots%20e%20coli%22Page 8 of 49 Special Local Needs uses include indoor f ogger treatments using pirimiphos-methyl for ornamental bulbs in Washington State and Michiga n. Up to 0.224 lbs. a.i. per 1,000 cubic feet of space may be applied for these uses.

There are no restrictions related to the use sites where pirimiphos-methyl can be used. In addition, for pirimiphos-methyl eartag uses, the maximum quantity of cattle treated or the maximum frequency of application per use site is not specified on product labels.

Discussion of Eartag Use Sites

Potential pirimiphos-methyl use sites for cattle eart ags, based alone on areas where cattle reside
associated with commercial li vestock production operations, may in clude pasture sites, rangeland, and feedlots. Out of all of these use sites, the feedlot use site is expected to possess the highest concentration of cattle by far. A ccording to USDA’s Feedlot Report from 2011 4 , small feedlots equal to or less than 1,000 head of cattle accounted for the vast majority of sites accounting for 97.1 percent of feedlots nationwid e, while larger feedlots only accounted for 2.8 percent of total sites. While widely variable, pasture and range land sites are expected to possess concentrations of cattle at far less head per acre than at feedlots, most of wh ich contain no more than 1,000 head
of cattle.

However, while feedlots may appear to be a vulne rable use site related to insecticidal eartag use based on cattle density as describe d above, there is evidence to sugge st that feedlots are not areas where eartags are used frequently, if at all, considering that piri miphos-methyl eartags are used to control infestations of horn fly and face fly pests. Feedlots are generally not recognized as suitable
habitats to maintain sustainable populations of horn flies and face flies since these insects require stagnant soils and fresh manure for their reproduction cycles with inc ubation of fly larvae. To this point, the dense presence of cattle is known to gene rate large and constant turnover of soil and manure matter at feedlots. Therefore, horn fly and face fly infestations and related pirimiphosmethyl eartag usage are expected to be most co mmon at pasture and rangeland sites as opposed to feedlot sites. This information is conveyed by multiple state agricultural extension services (e.g., Alabama, Mississippi, Kentucky, an d Nebraska) where eartag usage is common or wh ere feedlots are present (refer to Secti on 9 for complete citations).



## 3. Exposure Characterization

Registrant-submitted data defini ng the physical, chemical, fate and transport characteristics associated with pirimiphos -methyl are summarized in Table 1 . As part of registration review, available environmental fate studies for pirimip hos-methyl have been reevaluated. The fate and transport of pirimiphos-methyl in the environment is discussed below.

4 Full Citation:.U.S. Department of Agriculture (USDA). 20 11. Feedlot 2011 Report, Part I: Management Practices on US Feedlots with a Capacity of 1,000 or More Head. United States Department of Agriculture. Available online

at:. http://www.aphis.usda.gov/animal_health/nahms/feed lot/downloads/feedlot2011/Feed11_dr_PartI.pdf . Accesed
December 2015.Page 9 of 49 Table 1. General physical-chemical and envi ronmental fate properties of pirimiphosmethyl.

Chemical/Fate parameter Value Source (MRID) Study Acceptability

Physical Chemical Properties

Chemical Structure and SMILES
Code

CCN(CC)c1nc(C)cc(OP(=S) (OC)OC)n1 Product Chemistry

(MRID
00129333 N/A

Molecular Weight (g/mol) 305 Product Chemistry

(MRID 00129333) N/A

Vapor Pressure (torr at 30°C) 1.1 x 10 -4 Product Chemistry

(MRID 00129333) N/A

Octanol-water Partition Coefficient (Log K OW at 20°C) 4.2 Product Chemistry

(MRID 92147003) N/A

Octanol-air Partition Coefficient (Log K OA ) 8.743 EPI Suite (KOAWIN v. 1.1 estimate) N/A

Water Solubility (mg/L; at 20°C) 9.9 mg/L at pH 5.2 8.6 mg/L at pH 7.3 9.3 mg/L at pH 9.3 Product Chemistry

(MRID 92147003) N/A

Henry's Law Constant (atm-m 3

mol -1 ) 5.105 x 10 -6 EPI Suite (HENRYWIN v. 3.10) N/APage 10 of 49 Chemical/Fate parameter Value Source (MRID) Study Acceptability

Soil-water partition coefficients (K d ) England Soils 5 : LS1: 15.6 mL/g (OC = 1.60%) LS2: 27.4 mL/g (OC = 1.69%) LS3: 32.7 mL/g (OC = 2.97%) S: 11.6 mL/g (OC = 0.29%) SiCL: 161.9 mL/g (OC = 1.63%) SL: 45 mL/g (OC = 1.92%) MRID 48355601 Supplemental:

 Significant degradation was observed in low pH soils (S, SiCL, SL)

Abiotic Degradation 1

Hydrolysis half=lives (days) 7.3 days at pH 5 79 days at pH 7 54 – 62 days at pH 9 2 MRID 42982401
MRID 43177601 Acceptable

Aqueous photolysis half-life (days at 20°C) 3 0.2 days
IUPAC Pesticide Properties
Database 6 N/A

Photolysis in air half-life (hours at 25°C) 2.4 hours
0.802 hours SRC Database
EPI Suite (AopWIN v. 1.92) N/A

Soil Photolysis half-life (days) No Data Available - N/A

Biotic Degradation 1

Aerobic Soil Metabolism half-life (t 1/2 in days) England Soils 5 :

SL1: 33.6 days (OC = 3.70%, pH7.1) SL2: 28.7 days (OC = 1.00%, pH6.6) L: 42.7 days (OC = 6.0%, pH7.5) P: 31.5 days (OC = 36.2%, pH6.0) MRID 135358 Supplemental:

 Potential degradation

associated with the extraction procedures
not addressed.

 Pertinent test

conditions (e.g., temperature and moisture content) throughout the studies not reported.Anaerobic Soil Metabolism halflife (days) 4 England Soils 5 :

SL1: 36.4 days (OC = 3.7%, pH7.1) L: 31.5 days (OC = 6.0%, pH7.5)

Aerobic Aquatic Metabolism halflife (days) No Data Available - N/A

Anaerobic Aquatic Metabolism half-life (days) No Data Available - N/A

Field StudiesPage 11 of 49 Chemical/Fate parameter Value Source (MRID) Study Acceptability

Terrestrial Field Dissipation No Data Available - N/A

Bioaccumulation

BCF Fish 274X SRC Database
EPI Suite (WSKOW v. 1.42) N/A

1 Half-lives based on first order rate constant, k (t 1/2 = ln2/k) derived from Time – Ln(Concentration) regression.

2 Half-life range at pH9 among multiple replicates reported.

3 Estimated based on DT-50 value.

4 Half-life ranges based on replicates with flooded water soil atmosphere reported.

5 Soil texture identifiers: SLn: Sandy lo am replicate, LSn: Loamy sand replicat e, L: Loam, P: Peat, SiCL: Silty

Clay Loam

6 Available on-line: http://sitem.herts.ac.uk/aeru/iupac/



### 3.1 Transport and Dissipation Pathways

The measured soil-water partition coefficients (K d ) for pirimiphos-methyl residues range between 11.6 mL/g to 161.9 mL/g. These measured partition co efficients in soil are poorly correlated to organic carbon content (r 2 = 0.012). The water solubility limit of pirimiphos-methyl ranges between 8.6 to 9.9 mg/L. Both pirimiphos-methyl’s values of solubility a nd sorption coefficients indicate that pirimiphos-methyl resi dues will partition both to the sorbed phase and dissolved phase in soil and aquatic sediment. Therefore, pirimi phos-methyl can be transported to offsite water bodies via runoff and erosion processes.

The vapor pressure of 1.1 x 10 -4 torr suggests that pirimiphos-methyl can exist in the vapor-phase. However, the photolysis in air half-life of be tween 0.802 and 2.4 hours sugge sts that the residence time of pirimiphos-methyl vapors in air will be limited. Furtherm ore, no VOCs (including vaporphase pirimiphos-methyl) were detected in any vol atile trap in the aero bic and anaerobic soil
metabolism studies summarized above in Table 1 . The screening analysis presented in Section
3.4 verifies that pirimiphos-methyl exposure via the air and inhala tion exposure pathway is not of

concern.



### 3.2 Degradation

The major degradation pathway for pirimiphos-m ethyl O-(2-Diethylamino-6-methylpyrimidin-4- yl) O,O-dimethyl phosphorot hioate) is hydrolysis, especially in acidic environments. Hydrolysis half-lives from laboratory studies ra nged from 7.3 days at pH 5, to 79 days at pH 7 with a half-life of 54 – 62 days at pH 9. In acidic environments, the major degradate was 2(diethylamino)-4- hydroxy-6-methyl pyrimidine (hereafter referred to as degradate no. 1). In the pH 5 solution, degradate no. 1 reached maximum levels up to 87.3 days post treatment of the overall material
balance. In neutral and alkaline environments , degradate no. 1 was also found at major levels along with the degradate no. 2 (exact chemical na me defined in the executive summary of this document). In the pH 7 solution, degradate nos . 1 and 2 reached maximu m levels of 22.5 % andPage 12 of 49 26.5% of the overall material balanc e at 90 days post-treatment, resp ectively. In the pH 9 solution, degradate no. 1 and 2 reached levels of 21.0 a nd 18.2%, respectively of the overall material balance. Degradate no. 1 did not retain the organophosphate (P=S bond) linkage, whereas degradate no. 2 did.

Aqueous photolysis is also expected to be a si gnificant degradation process for pirimiphos-methyl with an experimentally-determined DT 50 of 0.2 days. Pirimiphos-methyl is also expected to be photolabile in air, with experimentally determined half -lives ranging between 0.802 – 2.4 hours (see Table 1 above).

Pirimiphos-methyl degradation in soil occurs at similar rates and appears to be mediated by hydrolysis, with half-lives ranging between 28.7 – 42.7 days in four soils. The major metabolite
from aerobic and anaerobic soil metabolism is de gradate no. 1 (defined above) which formed at levels up to between 37 – 66% of applied. Major levels of unext ractable residues consistently occurred throughout all tested soils , in the range of up to 28.2 – 66.3% of the applied material, and a nonpolar extraction solvent was not used to extract residues partitioned to soil. However, given pirimiphos-methyl’s high sorption to soil (see Section 3.1 above) and partially thorough extraction method utilizing acetone followed by methanol extr action solvents, residues appear to be bound to sediment. No Agency guideline studies have been conducted to determine the biodegradation of pirimiphos-methyl in water or its dissipation in the field.

Degradate no. 1 did not maintain the organophosphate moiety (P=S bond) and is not expected to possess toxicity exceeding that of parent pirimiphos-methyl. However the organophosphate moiety was maintained with degr adate no. 2. Therefore, the poten tial for toxicity exists with degradate no.2. Please refer to Appendix E for further information on the formation of degradates,
and Table 8 of Section 4.3 supporting the findings on the toxici ty of the degrad ates relative to parent-pirimiphos-methyl.



### 3.3 Bioaccumulation

A log K ow of 4.2 indicates that pirimiphos-methyl is sufficiently hydrophobic for binding to fatty tissue for aquatic organisms as well as available se diment. While there are no BCF in fish studies available, a regression K ow –based model suggests that the BCF value for pirimiphos-methyl is approximately 274X in aquatic organisms. This BCF further indicates the high potential for pirimiphos-methyl residues to build up in the tissues of aquatic biota.



### 3.4 Exposure Pathways

Pirimiphos-methyl and its organophosphate demet hylated degradate [degradate No. 2] are considered to be the primary stressors in this risk assessment. The degradate formed at major levels of up to 26.5% of applied due to hydrolys is (at pH7). For further information on the formation of degradates please refer to Appendix E . Furthermore, the de gradate’s toxicity is likely similar to the parent compound given its si milar organophosphate moiety. Please refer to
Table 8 of Section 4.3 supporting the findings on the toxicity of the degradates relative to parent-Page 13 of 49 pirimiphos-methyl. Given the similar moietie s between parent piri miphos-methyl and the degradate, this risk assessment will use a total toxic residues approach in exposure estimates assuming equal toxicity for both constituents.

Potential exposure to aquatic a nd terrestrial organisms with pi rimiphos-methyl exists only with cattle eartag and post-harvest grain seed treatmen t uses. There is no ecological risk associated with the indoor fogger treatment to iris included in the Washingt on State Section 24(c) label and the indoor fogger, dip, and drench treatments to glad iola bulbs in the Michig an Section 24(c) label.

The identification of relevant environmental expos ure pathways to pirimiphos-methyl applications for this risk assessment evaluating impact to non-target organisms are discussed below:

 Aquatic Exposure : Pirimiphos-methyl may impact aquatic environments after off-site movement mainly from pasture use sites associated with cattle ear tag uses for lactating and beef cattle. Pirimiphos-methyl residues from treated cattle with ea rtags may washoff from
treated cattle and become embe dded within runoff in an accumulated form from pastures.
Freshwater and estuarine marine fish and invertebrates as well as aquatic plants in the water column may be impacted. In addition, benthic organisms resi ding in the bottoms of water bodies may also be impacted gi ven pirimiphos-methyl’s tendency to partition to sediment.
Refer to Section 3.5 of this document for the a quatic exposure assessment. Section 3.5 describes the use of GENEEC to evaluate piri miphos-methyl cattle treatments at pasture use
sites.

Given pirimiphos-methyl’s low application rates with post-harvest stored grain seed

treatments , there is a smaller potential for exposur e resulting from runoff of pirimiphosmethyl residues to nearby water bodies associat ed with this use pattern. Nonetheless, this exposure pathway was evaluated in Attachment A in the original problem formulation document (DP Barcode No. 362650, dated March 9, 2009). Please refer to this document
for further details.

 Dietary Exposure : Birds and mammals can potentially be impact ed through dietary routes resulting mainly from pirimiphos-methyl post-harvest stored grain seed treatment residues. Pirimiphos-methyl residues may be bioavaila ble on harvested corn and sorghum seeds which are harvested, treated during storage, and then re-planted the ne xt season. The dietary exposure analysis for pirimiphos-methyl was co mpleted in a memo responding to a waiver request for an avian reproduction study (DP Barcode 357626, dated February 18, 2011). The analysis using the T-REX model (version 1.4.1, 12/07/2006) s howed that there were no adverse impacts associated with post-harvest seed treatment uses for pirimiphos-methyl and therefore this pathway will not be further addres sed in this assessment. This model has since been updated to version 1.5.2 (06/ 11/2013) but the conclusions remain the same. Please see the data waiver response memo for details. T-REX is publically avai lable at the following
website: http://www.epa.gov/oppefed1/models/te rrestrial/trex/t_rex_user_guide.htm

Furthermore, piscivorous birds and mammals feeding on contaminated fish may potentially be exposed with pirimiphos-methyl residues bi oavailable from exposed aquatic organismsPage 14 of 49 primarily due to washoff and subs equent runoff associated with eartag uses

. Bioaccumulation of pirimiphos-methyl residues is possible in fish given pirimiphos-methyl’s Log K ow value of 4.2. There is no quantitative met hod available to evaluate this route of exposure for the eartag use. The K OW -based Aquatic BioAccumulation (KABAM, v.1.0) model is available but without all necessary inpu ts available. Please see the Risk Description section for an analysis with KABAM using co nservative assumptions . Fixed equivalent maximum application rates cannot be defined with eartag uses given the nature of this use pattern and information available on labels. The application rate is a key factor for determining the amount of pirimiphos-methyl re sidues bioavailable to piscivorous birds since it largely impacts the wa ter body concentrations which can be expected. Please refer to the Risk Description Section ( Section 5.2 ) for further discussion regarding risks which may occur resulting from this exposure pathway as well as a descriptio n of the uncertainties which exist related to this expos ure pathway for pirimiphos-methyl.

 Terrestrial plants and T errestrial Invertebrates: Sporadic and low density of pirimiphosmethyl residues are expected on pasurelands with cattle treated are expected. As eartag uses are not associated with a foliar spray, there w ould be no drift expected from these uses of pirimiphos-methyl. Therefore, exposure to terr estrial plants and terr estrial invertebrates which forage on and around plants will be limited.

 Drinking water exposure : An analysis using the Screening Imbibition Program (SIP version 1.0, 6/15/2010) indicated that drinki ng water exposure alone is not a potential
concern for mammals on an acute basis. Conversely, exposure though drinking water alone is a potential concern for mammal s on a chronic basis as well as for birds on an acute basis. As an avian reproduction study is not availabl e for pirimiphos-methyl , risk could not be precluded from the model. There is currently no refinement in the risk assessment process
to further characterize the like lihood of this exposure pathway be ing complete or the relative risk associated with this pathway. It is an uncertainty whether significant residues of pirimiphos-methyl would exist in puddles present in feed lots as well as the frequency to
which birds and other mammals visit these feed lots to potentiall y be exposed through drinking water. SIP is available publically at: http://www.epa.gov/oppefed1/models /terrestrial/sip/sip_user_guide.html

 Inhalation exposure to terrestrial animals: The potential for pirimiphos-methyl inhalation exposure only exists via the va por-phase. Inhalation to spra y droplets would not exist for pirimiphos-methyl since it is not applied in a sp ray form for eartag and seed treatment uses.
The STIR model is used to initi ally evaluate this exposure pa thway. The Screening Tool for Inhalation Risk (STIR, version 1.0; 11/23/2010)m odel relies on user-inputs of vapor pressure as well as mammal inhalation, mammal oral, and inhalation oral toxicity data to determine need to address the inhalation exposure pathway in the risk assessment. The results of STIR, indicate the need to proceed to further refinements only for birds, as indicated by the ratio of vapor dose to adjusted inhalation LD 50 is a value that indicates the need to proceed to refinements. STIR may be accessed on-line at: http://www.epa.gov/oppefed1/models/te rrestrial/stir/stir_user_guide.html

 The likelihood of exposure via inhalation for bird s can be explored further using the HealthPage 15 of 49 Effects Division (HED) Tier 1 Air Exposure Mo del (Tool Developed by Chuck Peck, version 1, dated 7/22/13). However, it should be noted that this model accounts for vapor-phase release from soil surfaces, and can depict th e potential release of pi rimiphos-methyl from the grounds of pasturelands after it washes off from eartags. Since no off-gasing data are available for pirimiphos-methyl from eartags, exposure resul ting from pirimiphos-methyl’s release from soil can only be assessed. As suc h, this exploration will conservatively assume that 100 percent of pirimiphos-methyl are availa ble to off-gas from the grounds of pastures after washoff from the eartags. The HED Ti er 1 Air Exposure Model contains additional physical chemical properties such as vapor pressure, solubility, and soil-water partition
coefficients to determine the upper-bound volatile flux rate of pirimiphos-methyl from soil. This flux rate is carried over to EPA’s AERSCREEN dispersion model to determine the resulting vapor-phase estimated exposure concen tration (EEC) in air. Given the equivalent

avian LC 50 value of 930.75  g/m 3 in air estimated from STIR 5 for birds and air EEC 43.48

 g/m 3 (equivalent to a risk quotient of 0.05), a more refined anal ysis for inhalation exposure of pirimiphos-methyl released from soil in the vapor-phase is not needed.

The analyses using the STIR model and HED Tier 1 Air Exposure model is presented in
detail in Appendix C

. 

### 3.5 Aquatic Exposure Analysis

Post-Harvest Stored Grain Seed Treatment Uses

Please refer to Attachment A of the original problem formul ation document (DP Barcode No. 362650, dated March 9, 2009) for the evaluation of aquatic exposure resulting from post-harvest seed treatment uses of pirimiphos-methyl. Upper-bound estimated e xposure concentrations (EECs) in surface water were calculated using the pe5 shell for the PRZM/EXAMS model, ranging up to 0.002 μg/L. 6

Cattle Ear Tag Uses

Attachment B of the original problem formulation docum ent also presented a preliminary analysis of aquatic exposure occurring from ear tags. Howe ver, the exposure analysis is updated in this risk assessment. The exposure analysis presents an evaluation of the number of heads of treated cattle leading to adverse impacts ( i.e ., LOC exceedances) rather than deterministic risk quotients

5 The equivalent avian inhalation endpoint of 930.75  g/m 3 is calculated from the dose-based adjusted avian

inhalation LD 50 of 0.468 mg/kg-bw determined from STIR (see Table C.1

, Appendix C ). The conversion is shown as follows, based on equation 9 within the STIR User’s Manual:

LC 50 = LD 50 adjusted / (Abs x CF x D x A)] x 1,000 L/m 3 x 1,000  g/mg= 930.75  g/m 3

where LD 50 adjusted = 0.468 mg/kg-bw, Abs (chemical absorption into tissue) = 1.0, D (exposure duration) = 4 hours, A (animal activity factor at rest) = 1.0, CF {conversion factor = [avian inhalation rate (2,514.1 cm 3 /hr) x

0.001 L/cm 3 ]/body weight (0.02kg)} = 502.82 L/hr

6 It should be noted that K d /K
oc and aerobic soil metabolism half-lives inputs used in the exposure analysis for postharvest seed treatments in the problem formulation were di fferent from the analysis w ith eartag uses presented in this document considering the preliminar y review status of environmental fate studies at that time. However, all inputs utilized in the problem formulation re sult in a conservative assessment of exposure.Page 16 of 49 based on an exposure scenario for which ecotoxicological data are available (freshwater fish and invertebrates). This approach captures of range of outcomes possible a ssociated with potential aquatic exposure with pirimiphos-methyl eartag us age while considering tw o major uncertainties: 1.) The amount of cattle that is simultaneously treated with pirimiphos-methyl, and 2.) The
amount washoff or washoff fraction from the treated cattle to the feedlot, which is then available for runoff to nearby water bodies.

Since runoff of pirimiphos-methyl is being evalua ted, aquatic exposure models can be used to evaluate the amount of pirimiphos-methyl eartgas that would be required to runoff in sufficient quantities to trigger adverse impacts to listed a nd non-listed aquatic species. The screening aquatic exposure model GENEEC (latest version dated 10/ 10/14, developed by Ron Parker) is used for this evaluation given that it uses a runoff scenario (modified to ex clude spray drift) from a generic 10-hectare treated area to a 1-hectare pond. The Surface Water Concentration Calculator (SWCC), which is normally used to assess runoff of pes ticide residues for cropped fields, is not employed in this case given the unique use pattern for eartags. The advers e impacts analysis incorporates the GENEEC estimated exposure con centration (EEC) in surface wate r normalized to one head of
treated cattle and avai lable acute toxicity data for freshwater fish and freshwater invertebrates to
determine the number of head of treated cattle meeting and exceeding the acute listed and nonlisted levels of concern (LOCs) for aquatic species. This analysis is presented in Section 5.1

.

The exposure analysis for pirimiphos-methyl use at pastureland use sites will evaluate the potential exposure which occurs from heads of cattle treate d simultaneously. It will be assumed that each head of cattle possesses two eartags containing 1. 92 grams a.i. each for a total of 3.84 grams (8.47

x 10 -3 lbs.) total of pirimiphos-methyl as permitted by th e label. From this s cenario, an application
rate can be calculated with th e initial assumption that the to tal amount of pirimiphos-methyl washes off from the treated cattle, is available for runoff, and that the resulting residue will be evenly distributed with the 10-hectare treated pa sture. From these assumptions, an equivalent application rate normalized to one head of treat ed cattle can be calcula ted considering the 3.84 grams (8.47 x 10 -3 lbs.) of pirimiphos load with each head of cattle and the 10-ha treated area. The resulting equivalent app lication rate is 3.43 x 10 -4 lbs./A per head of cattle [8.47 x 10 -3 lbs. ÷ (10 ha x 2.47 A/ha)]. Use sites larger than 10 hectar es are not evaluated since the amount of treated cattle is expected to be proporti onal to the pasture site size impacted by runoff. Therefore, the total pirimiphos-methyl runoff mass pe r unit area is expected to be conserved over all pasture land use site sizes and thus the effective app lication rate should no t be impacted.

However, the major uncertainty is the fraction of pirimiphos-methyl that could potentially wash
off from treated cattle. The 3.43 x 10 -4 lbs./A value is a high-end application rate assuming 100% of pirimiphos-methyl residues washes off. Theref ore, this aquatic exposu re analysis will use a bracketing technique, where the equivalent appli cation rate is linearly proportional to the amount that washes off. Accordingly, the application rate s for each of the washoff fractions (evaluated for 100%, 20%, 10%, 5%, and 1%) from treated cattle are shown in Table 3.

The remaining parameterization for GENEEC is composed of the physical chemical and fate properties of pirimiphos-methyl utilizing EFED Model Input Parameter Guidance 7 . All input parameter values for the aquatic exposure assess ment for pirimiphos-methyl cattle eartags are

7 Available on-line: http://www.epa.gov/oppefe d1/models/water/input_parameter_guidance.htmPage 17 of 49 shown in Table 2.

Table 2. Input parameter values used in GE NEEC for pirimiphos-me thyl adverse impacts analysis for cattle ear tag uses at pasture use sites.

GENEEC Input Parameter Input Value and
Unit Comment Source

Application Rate (lbs. a.i./A per head of treated cattle) See Table 3 Based on 3.84 gramsof pirimiphosmethyl per head of
treated cattle and 10-
hectare use site size for specified
washoff fraction Product label and
standard runoff exposure scenario
evaluated

Application Method Broadcast 1 No Spray Drift, Incorporated to Surface Only Consistent with washoff scenario for eartag use

Hydrolysis (t 1/2 ) 198 days Total Toxic Residue half-life includingparent pirimiphosmethyl and its OP demethylated degradate (see
Section 3.2 and Appendix E for
chemical name and identification) at pH

7 MRID Nos. 42982401

& 43177601

Aerobic soil metabolism (t 1/2 ) 39.1 days Parent only, OP demethylated degradate not detected in study

90 th percentile on the upper confidence
bound half-life from n=4 soils (refer to
Table 1 ) MRID 135358

EFED Model Input
Parameter Guidance

Aerobic aquatic metabolism (t 1/2 ) Stable Conservative assumption -

Solubility in Water at 20oC 8.6 mg/L Product Chemistry Product Chemistry (MRID 92147003) Soil-Water Partition Coefficient (K d ) 49.03 mL/g Average value from n=6 soils (refer to
Table 1 ) MRID 48355601

EFED Model Input
Parameter Guidance Aqueous Photolysis (t 1/2 ) 0.2 days DT-50 value IUPAC Pesticide Properties Database 2

1 Broadcast application method consistent with chemical distribution associated with granular application as defined

in GENEEC.

2 Available on-line: http://sitem.herts.ac.uk/aeru/iupac/

The resulting EEC normalized to one head of trea ted cattle for each washoff fraction evaluated isPage 18 of 49 provided in Table 3 (see Appendix B for the sample GENEEC file). The EECs normalized to one head of treated cattle along with endpoints av ailable from freshwater fish and freshwater invertebrate toxicological studies will be used to compute the number of treated ca ttle leading to adverse impacts resulting from eartag use. This analysis is possible since the EECs are directly proportional to the amount of cattle treated, assuming all cattle possess the same number of eartags. In this assessment, all cattle are assumed to contain two eartags, one on each ear. The normalized
EECs to one head of cattle shown in Table 3 is used to determine th e amount of treated cattle leading to adverse impact. Th is evaluation is presented in Section 5.1

.

Table 3. GENEEC pirimiphos-methyl surface water EECs at equivalent application rates
normalized to one head of treated cattle for certain washoff fractions.

Input/Output Variable Washoff Fraction

100% 20% 10% 5% 1% Equivalent Application Rate (lbs. a.i./A per head of treated cattle) a,b 3.43 x 10 -4 6.85 x 10 -5 3.43 x 10 -5 1.71 x 10 -5 3.43 x 10 -6

Surface Water EECs (μg/L per head of treated cattle) b 2.49 x 10 -3 4.98 x 10 -4 2.49 x 10 -4 1.25 x 10 -4 2.49 x 10 -5

a For calculation of the equivalent application rate, please refer to the discussion above Table 2.

b Based on 10-hectare size use site.

Water Quality Monitoring Data

According to a recent search of existing monitoring databases, there are no surface water or ground water data monitoring data availa ble for pirimiphos-methyl. However, this does not indicate that detections of pirimiphos-methyl are not possible, es pecially in the vicinity of pasture lands where pirimiphos-methyl is used. Rather, EFED is not aware of any attempts to measure pirimiphosmethyl in the environment. Therefore, this ri sk assessments relies sole ly on upper-bound exposure estimates provided by environmental fate and transport models such as GENEEC.



### 3.6 Terrestrial Exposure Analysis

Please refer to the memo that wa s completed in response to a waiv er request related to the Avian Reproduction study (DP Barcode 357626, dated Februa ry 18, 2011) for the terrestrial exposure assessment for pirimiphos-methyl uses. This memo contains the dietary exposure analysis for pirimiphos-methyl resulting from post -harvest stored grain steed treatment use. The analysis used label information to calculate upper-bound exposure concentrations bioavailable to birds and mammals using the TREX model (version 1.3.1, 12/ 07/2006). This model has since been updated to version 1.5.2 (06/11/2013) but th e conclusions remain the same.

As stated in Section 3.4 ., there is limited exposure to non-targ et terrestrial organisms associated with the cattle eartag uses of pirimiphos-methyl. It cannot be stated with certainty that non-target terrestrial organisms would not be present at a pastur e use site but it is not expected that terrestrial organisms would be exposed to pirimiphos-methyl re sidues to a large extent. Therefore, no further analysis addressing exposure to non-target terres trial organisms resulting from pirimiphos-methyl cattle eartag uses is presente d in this risk assessment.Page 19 of 49 

## 4. Ecological Effects Characterization

The ecological effects characte rization for pirimiphos-methyl is based upon registrant-submitted toxicity data for the TGAI (parent pirimi phos-methyl) and for specified formulations.



### 4.1 Aquatic Effects Summary

Pirimiphos-methyl exposure effects on aquatic organisms were determined by assessing
freshwater fish and freshwater i nvertebrates. For these two taxa , only acute exposure studies were
available. There were no acute or chronic st udies available for estuarine/marine fish and invertebrates nor for any aquatic plant species. Additionally, there were no data available to
evaluate the subchronic and chronic toxicity of pirimiphos -methyl to sediment dwelling invertebrates. Each study’s species tested, endpoint, and MRID numb er are tabulated below separated by taxa.

Toxicity to Freshwater Fish

There are two acute freshwater fi sh toxicity studies available fo r pirimiphos-methyl. In an acute study conducted with the rainbow trout ( Oncorhynchus mykiss, MRID 00103924), fish were exposed to pirimiphos-methyl concentrations (88.9% purity) ranging from 0.18 to 0.75 mg a.i/L in a continuous flow-through system. Total (100 %) mortality occurred at the highest treatment concentration. Clinical signs of toxicity included darkening of skin and gill inflammation but these effects were not quantified in the individual trea tment concentrations. The 96-hour LC 50 was determined to be 0.40 mg a.i/L (95% CI: 0.34 – 0.45) and this study is cla ssified as acceptable.

In an acute toxicity study c onducted with both rainbow tr out and bluegill sunfish ( Lepomis macrochirus, MRID 00103925), fish were exposed at con centrations ranging from 0.33 – 2.2 mg a.i/L and 1.0 – 4.7 mg a.i/L, respect ively. There were no cl inical signs of toxicity observed in the rainbow trout study but in the bluegill sunfis h study, signs of toxicity included rapid jaw movements, disorientation, keeli ng, and gill inflammation (concentra tions at which the signs were observed were not reported). The 96-hour LC 50 values for rainbow trout and bluegill sunfish were determined to be 1.18 (0.98 – 1.47) and 2.80 (2.46 – 3.10) mg a.i/L, respectively. This study is classified as acceptable.

Table 4. Summary of Acute Toxicity Data for Freshwater Fish Exposed to Pirimiphosmethyl

Species Study Duration (Exposure System) Purity of Test Substance (as %) LC 50 (mg a.i/L) 1,2,3 (95% CI;

slope) Toxicity
Classification (MRID)

Rainbow trout ( Oncorhynchus mykiss ) 96-hour (flowthrough) 88.9 0.40 (0.34 – 0.45; 8.04) Highly toxic (00103924)Page 20 of 49 Species Study Duration (Exposure System) Purity of Test Substance (as %) LC 50 (mg a.i/L) 1,2,3 (95% CI;

slope) Toxicity
Classification (MRID)

Rainbow trout 96-hour (flowthrough) 84 1.18 (0.98 – 1.47; N/A) Moderately toxic (00103925) Bluegill sunfish ( Lepomis
macrochirus ) 2.80 (2.46 – 3.10; 10.5)

CI: Confidence interval. LC 50 : Lethal concentration to 50% of the population. N/A = not applicable

1 Bolded values represent the most sensitive toxicity endpoint s for freshwater fish exposed to parent pirimiphosmethyl

2 Based on mean measured concentrations.

There is one acute freshwater in vertebrate toxicity study availa ble for pirimiphos-methyl. In a study with Daphnia magna (MRID 00103926), organisms were e xposed to both TGAI (99.5% purity) and formulated pirimiphos-methyl (50% pur ity) at varying concentrations. TGAI and formulated product exposures ranged from 0.01 – 50 μg a.i/L. There was no mention of any clinical signs of toxicity being obser ved throughout the st udy. The 48-hour EC 50 was determined to be 0.21 μg a.i/L (0.15 – 0.31) and 0.11 μg a. i/L (0.08 – 0.15) for TGAI and formulated pirimiphos-methyl, respectively. This study was cl assified as acceptable for the TGAI component and supplemental for the formulated product compone nt. The rationale for supplemental status for the formulated product component was that th ere was no need to cite a formulation study at
the time of the review. It was further stated this classification could be upgraded to acceptable if that status changed.

Table 5. Summary of Acute Toxicity Data for Freshwater Invertebrates Exposed to Pirimiphos-methyl

Species Study Duration (Exposure System) Purity of Test Substance (as %) LC 50 (μg a.i/L) 1 (95% CI;

slope) Toxicity
Classification (MRID)

Water flea ( Daphnia magna ) 48-hour (flow-through) 99.5 0.21 (0.15 – 0.31; N/A) Very highly toxic (00103926) 50 0.11 (0.08 – N/A)

CI: Confidence interval. LC 50 : Lethal concentration to 50% of the population. N/A = not applicable

1 Based on mean measured concentrations.



### 4.2 Terrestrial Effects Summary

There is one avian acute oral a nd three avian subacute dietary studies available for pirimiphosmethyl. In an acute oral study with the northern bobwhite quail, birds were exposed to control or nominal treatment doses of 19.4, 32.4, 54, 90, 150, a nd 250 mg a.i/kg bw. There was total (100%) mortality in the three highest doses and 80% mort ality in the 54 mg a.i./kg bw group. Clinical signs of toxicity were observed at all but the lowest treatment group (19.4 mg a.i/kg bw) that included ruffled appearance, depression, reduced reac tion to external stimu li, loss of coordination, wing droop, lower limb weakness, walking stiffly, pr ostrate posture, shallow and rapid breathing, salivation, loss of righting reflex, minor muscle fasciculations, and muscle spasms. A marked weight loss was also observed at th ese treatment doses. The 14-day LD 50 was determined to bePage 21 of 49 40 mg a.i/kg (32 – 50). This st udy was classified as acceptable ( Table 6 ).

In a subacute dietary study with the mallard duck, birds were exposed to control or concentrations in the diet of 215, 464, 1000, 2150, and 4640 ppm. Total (100%) mortality was observed in the two highest treatment co ncentrations and 80% at the middle treatment concentration (1000 ppm). Clinical signs of toxicity incl uded lethargy, labored respiration, and loss of coordination. The 8- day LC 50 was determined to be 633 ppm (453 – 883). Th is study is classified as acceptable (MRID 00107422).

In a subacute dietary study with the northern bo bwhite quail, birds were exposed to control or concentrations in the diet of 21, 46, 100, 215, and 464 ppm. Total (100%) morality was observed in the highest treatment concentration. Clinical signs of toxicity incl uded wing droop, depression, loss of coordination, and loss of righting reflex. This study is classified as acceptable (MRID 00107423). In a second dietary st udy conducted with the mallard duck, birds were exposed to control or concentrations of 163, 325, 650, 130 0, 2600, and 5200 ppm. Total (100%) mortality was observed at the four highest treatment con centrations and 60% was observed at the 325 ppm
treatment concentration. Clinical signs of toxicity were observe d at the five highest treatment concentrations and included subdued behavior, huddling together, unsteadiness of gait, drooped wings, and stumbling/lying on the pen floor. The 8-day LC 50 was determined to be 284 ppm (164 – 643). This study (MRID 42037001) is classified as supplemental since there was no confirmatory analysis of concentr ations in the feed was conducted.

Table 6. Summary of Acute Or al and Subacute Dietary Toxi city for Birds Exposed to Pirimiphos-methyl

Species Study Type Purity of Test Substance (as %) LD 50 (mg a.i/kg bw)
or LC 50 (mg a.i/kg diet) 1,2 (95% CI; slope) Toxicity
Classification (MRID)

Northern Bobwhite quail

( Colinus virginianus ) Avian
Acute Oral 89.8 40 (32 - 50; 7.3) Highly toxic (43442101)

Mallard duck ( Anas platyrhynchos ) Subacute Dietary Not specified (study report did indicate TGAI) 633 (453 – 883; N/A) Moderately toxic (00107422)

Northern Bobwhite quail

( Colinus virginianus ) Subacute dietary Not specified (study report did indicate TGAI) 207 (106 – 407; N/A) Highly toxic (00107423)

Northern Bobwhite quail

( Colinus virginianus ) Subacute dietary 89.3 284 (164 – 643; N/A) Highly toxic (42037001)

CI: Confidence interval. LD 50 : Lethal dose to 50% of the population. N/A = not applicable

1 Bolded values represent the most sensitive toxicity endpoints for birds exposed to pirimiphos-methyl

2 Based on mean measured concentrations.

Mammals

In an acute oral study available for pirimiphos -methyl, formulated (75.4% purity) product was administered to rats (MRID 00126257). There are no acute oral studies avai lable for rats with technical pirimiphos-methyl. The actual treatment levels the ra ts were exposed to was not available in the DER and the study repor t was difficult to interpret. The LD 50 was determined to be >2400 mg/kg, which classifies pirimiphos-methyl as practica lly non-toxic to mammals on anPage 22 of 49 acute oral basis. Clinical signs of toxicity included diarrhea, lethargy, decreased respiratory rate, and body tremors at the lowest treatment dose. There was no mortality in the lowest treatment dose and 75 and 100% mortality in the middle and highest treatmen t doses, respectively. This study was classified as acceptable.

In a two generation reproduction study, rats were fed diets containing t echnical pirimiphos-methyl (86.7% purity) at dose levels of control, 10, 40, and 160 ppm. There were no treatment related effects observed on any reproductive parameters. There was a reduction in body weight (percent effect or statistical significance not indicated in DER or study report) at th e highest treatment concentration. There were sporadic findings of clinical signs of t oxicity that were not associated with any one generation nor were they observed in a dose responsive manner. These included hair loss, swollen forepaw, protruding eyes, piloerect ion, and trembling. The most sensitive endpoint was significant (p<0.05) plasma cholinesterase inhibition that occurred at all treatment
concentrations and therefore a defini tive NOAEL could not be established.

Table 7. Summary of Acute Oral and Chronic Toxicity for Mammals Exposed to Pirimiphos-methyl

Species Study Type Purity of Test Substance (as %) LD 50 (mg a.i/kg bw) or NOAEL (effects) 1

(95% CI; slope) Toxicity
Classification (MRID)

Norway rat ( Rattus norvegicus ) Acute oral toxicity 75.4 >2400 (N/A; N/A) Practically nontoxic (00126257) 2-generation reproduction 86.7 <10 ppm (cholinesterase inhibition) -- (43726801)

CI: Confidence interval. LD 50 : Lethal dose to 50% of the population. N/A = not applicable

1 Bolded values represent the most sensitive toxicity en dpoints for mammals exposed to pirimiphos-methyl

Terrestrial Invertebrates

There is one study available to char acterize the acute contac t and oral toxicity to adult honey bees. The study (MRID 05001991) tests several other chemi cals and only provides the acute contact and
oral LD 50 determinations with no accompanying information on sublethal effects, confidence intervals, or any other narrative pertaining to study design and te st methods. The acute contact
and acute oral LD 50 were determined to be 0.13 and 0.39 μg a.i/bee, respectivel y which classifies pirimiphos-methyl as very hi ghly toxic to honey bees.



### 4.3 Degradate toxicity

As described in Section 3.2 , pirimiphos-methyl is subject to de gradation to various products via multiple pathways. There are no available toxicity studies to characterize the toxicity of the degradation products of pirimiphos -methyl. Therefore, the ECOS AR (v.1.1) module of EPISUITE (v.4.1) was employed to estimate the toxicity of th ese degradates as compar ed to the registrant submitted studies available for parent pirimi phos-methyl. ECOSAR uses structure activity relationships (SAR) to predict the toxicity of compounds that share si milar structural moieties. For each degradate of pirimiphos-methyl, the most sensitive ( i.e. lowest) estimate of toxicity for a given taxa was tabulated below in Table 8 . Also shown are the ECOSAR estimates for parentPage 23 of 49 pirimiphos-methyl which corroborate the registrant submitted toxicity study for freshwater fish but under predict the toxicity to freshwater inve rtebrates by approximately one order of magnitude.

Environmental fate data indicate that two major ( i.e >10% of the applied residues) degradates form in the available hydrolysis study. One degradat e (degradate No.2), forming as a result of demethylated pirimiphos-methyl, preserves the or ganophosphate moiety of the parent compound. Accordingly, ECOSAR results shown in Table 8 below estimates similar toxicity of this degradate to that of parent pirimiphos-methyl. A second degradate, 2(diethylamino)-4-hydroxy-6-methyl pyrmidine (degradate No. 1), which loses the organophosphate moiety, is estimated by ECOSAR to be at least three orders of magnitude less toxi c to freshwater fish and invertebrates on an acute and chronic exposure basis. Please refer to Section 3.3 and Appendix E on the formation of this degradate. Based on this analysis, the stressor of concern for ecotoxicological risk will be the combined residues of parent pirimiphos-methyl and its demethylated organophosphate degradate ( i.e . degradate no. 2).

Table 8. ECOSAR predicted toxicity (mg a.i/L ) of the degradates of pirimiphos-methyl

Stressor (Endpoint Source) Endpoint (in mg a.i/L)

Freshwater
Fish LC 50 Freshwater
Invertebrate
EC 50 Chronic
Freshwater Fish
NOAEC Chronic

Freshwater
Invertebrate

NOAEC Pirimiphos-methyl (registrant submitted studies) 0.4 0.00021

Pirimiphos-methyl (ECOSAR estimates) 0.23 0.002 0.033 0.00000007

2(diethylamino)-4-hydroxy-6- methyl pyrimidine(degradate no. 1) (ECOSAR estimates) 396 39.1 40.7 2.68

O-2 diethylamino-6-methylpyrimidin-4-yl omethyl-phosphorothioate (degradate no.2) (ECOSAR estimates) 0.24 0.001 0.035 0.00007



### 4.4 ECOTOX Open Literature

Open literature studies are identified us ing EPA’s ECOTOXicology database (ECOTOX) (USEPA, 2007 c ), which employs a literature search engine for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. The evaluation of both sources of data can also provide insight into the direct and indirect effects of pesticides on biotic communities from loss of species that are sensitive to the chemicals and from changes in structure and functional characteristics of
the affected communities. A search of EC OTOX in October, 2014 yielded no endpoints more sensitive than those already available.



### 4.5 Review of Incident Data

The ecological incident information system (EIIS) is an EFED-maintained database that houses ecological incidents that have b een reported to the Agency. When available, EIIS includes datePage 24 of 49 and location of an incident, type and magnitude of effects observed in various species, use(s) of pesticides known or suspected of contributing to the incident, and results of any chemical residue analysis or other analyses conduc ted during incident investigation. EIIS incidents are categorized according to the certainty that the incident result ed from pesticide exposure. The OPP-maintained Incident Database System (IDS) and the Aggregat e Incident Database provi de incident counts at the chemical and product level but do not provide th e narrative information contained in EIIS. The Avian Incident Monitoring System (AIMS) is a database administered by the American Bird Conservancy that contains publicly available data on reported avian incidents involving pesticides. Many of the incidents listed in this database are also in the EIIS. Searches of the incident databases were conducted in November, 2014.

A search of EIIS, the IDS, Aggregate Incident Database, and AIMS returned no reported wildlife incidents involving pirimiphos-methyl.



## 5. Risk Characterization

5.1. Risk Estimation

Aquatic Exposure: Post-Harvest Stored Grain Seed Treatment Uses

PRZM/EXAMS runs (via pe5 shell) using the Georgia Farm Pond scenario, presented in the original problem formulation document do not indicate a concern for exposure to aquatic organisms in surface water with acute (one-in- ten year peak) pirimiphos methyl surface water EECs < 0.0018 ppb and chronic (one-in-ten year 60-day average) pirimiphos-methyl EECs < 0.0007 ppb 8 . The EECs result in risk quotients (RQs) for acute freshwater fish of <<0.01 and
<0.01 for acute freshwater invertebrates 9 . Despite pirimiphos-methyl’s potential for off-site movement, the most likely reason for low EECs is th e very low application rate on treated seed.
It is noted that the EECs are c onservative since the am ount of pirimiphos-methyl available for offsite transport was based on a standard seed trea tment use whereby degrada tion during storage time as well as release of residues from treated seeds were not taken into account. Since this analysis presented in the problem formulat ion did not reveal ri sk quotients above the level of concern, aquatic risks are not expected and therefore, are not further evaluated in this assessment.

Environmental exposure from pi rimiphos-methyl grain treatments are not expected during its application since the labels instruct pirimiphos-methyl to be applied as grain is stored. The Actellic label is especially explicit rest ricting use-sites off of farms. EFED recommends similar explicit language for the Execute label, which is the only other product used for post harvest grain storage treatments. Furthermore, for both labels, EFED recommends restricting pirimiphos-methyl use to corn and sorghum grain that is contained in doors or otherwise in storage containers, and

8 It should be noted that K d /K
oc and aerobic soil metabolism half-lives inputs used in the exposure analysis for postharvest seed treatments in the problem formulation were di fferent from the analysis w ith eartag uses presented in this document considering the preliminary review status of fate studies at that time. However, all inputs utilized in the problem formulation result in a more conservative assessment of exposure.

9 Based on surface water EEC and freshwater fish LC 50 = 404 ppb (MRID No. 00103924) and freshwater
invertebrate EC 50 = 21 ppb (MRID No. 00103926).Page 25 of 49 prohibiting its use in outdoor bunkers to more exp licitly ensure the intentional use of pirimiphosmethyl while minimizing exposure in the environment.

Aquatic Exposure: Cattle Ear Tag Uses

As mentioned in Section 3.5 , this risk estimation presents an evaluation of the number of heads of treated cattle leading to adverse impacts ( i.e ., LOC exceedances) rather th an deterministic risk quotients based on an exposure scenario with a fixed assumption on the number of simultaneous
treated cattle at the use site. The EECs normalized to one head of treated cattle for each washoff fraction, shown in Table 3 , are used along with endpoints ava ilable from freshwater fish and freshwater invertebrate toxicological studies to compute the number of tr eated cattle leading to adverse impacts resulting from eartag use. This analysis is possible since the EECs are directly proportional to the amount of cattle treated, assu ming all cattle possess two eartags. The number of treated cattle leading to adverse impacts fo r acute freshwater fish and acute freshwater invertebrates is presented in Table 9. The results presented in Table 9 are discussed further in context with the cultural practices of cattle and pa sture operations in the Risk Description section ( Section 5.2 ) below.

Table 9. Summary of pirimiphos-methyl treate d heads of cattle to tr igger adverse impacts for listed and non-listed species on an acute basis.

a Acute concentration of concern for freshwat er fish based on the following calculation: Rainbow Trout acute endpoint (LC 50 = 404  g/L) x 0.05 or 0.5 (LOCs for listed and non-listed species). Rainbow Trout acute endpoint
from MRID No. 00103924.

b Acute concentration of concern for freshwater invertebrates based on the following calculation: Daphnid acute endpoint (EC 50 = 0.11  g/L) x 0.05 or 0.1 (LOCs for listed and non-listed species). Daphnid acute endpoint from
MRID No. 00103926.

c Heads of Cattle Causing Concern = Concentration of Concern (  g/L) ÷ GENEEC peak EEC (  g/L) for each
washoff fraction shown in Table 3. Aquatic Species and

Adverse Impacts
Thresholds PirimiphosMethyl Water Body
Concentration

of Concern (  g/L) Head of Treated Cattle Causing Concern Given Wa shoff Fractions (number of cattle) c

100% 20% 10% 5% 1%

Freshwater Fish

Acute Listed Species (LOC = 0.05) 20.2 a 8,038 40,188 80,376 160,751 803,757

Acute NonListed Species (LOC = 0.5) 202 a 80,038 400,188 800,376 1,607,510 8,037,570

Freshwater Invertebrates

Acute Listed Species (LOC = 0.05) 0.0055 b 2 10 20 40 200

Acute NonListed Species (LOC = 0.5) 0.055 b 20 100 200 400 2,000Page 26 of 49 Terrestrial Exposure: Post-Harvest Stored Grain Seed Treatment Uses

The registrant provided an argument on why there would be negligible exposure for terrestrial organisms resulting from the stored grain seed treatment uses of pirimiphos-methyl. These lines of evidence were originally captured in a waiver request submitted by the registrant for an avian reproduction study, contending that there would be in sufficient exposure to necessitate such a test (“EFED Response to Avian Reproduction St udy - OCSPP 850.2300 – Waiver Request for Pirimiphos-methyl,” D357626, February 18, 2011). The main arguments were made from an absence of exposure basis (as described below), a nd unnecessary use of animals for toxicity testing when compared to overall valu e to the risk assessment.

Estimated environmental concentrat ions (EECs) were ca lculated from the highest rates on current labeled seed treatment uses for sorghum and corn (0.48 lbs a.i per 30 tons of grain, Acetallic® 5E Insecticide). The registrant provided an exam ple where it was assume d that only 1% of the pesticide will remain on the soil surface due to spillage (Imazilil Reregistration Eligibility Decision; US EPA, 2005). However, because the a pplication rate is so lo w, either 1% or 100% assumptions for seed consumption do not result in high exposure levels. The maximum exposure concentration is 2.03 mg a.i/kg-bw/day based on the assumption of 100% bioavailability following seed treatment. Therefore, maximum potential exposure levels of pirimiphos-methyl from seeds treated in the field appe ars to be very low.

The determination made previously at the time of the problem formulation regarding risk resulting from this pathway remains unchanged and therefore risk to terrestrial organisms resulting from the storage of treated seed is expected to be below Agency levels of concern.

Terrestrial Exposure: Cattle Ear Tag Uses

Given the limited exposure to non-tar get terrestrial organisms associat ed with the spotty nature of cattle eartag uses of pirimiphos-met hyl at pastureland use sites, ri sk quotients are no t expected to exceed the LOCs for any non-target terrestrial organism.



### 5.2. Risk Description

This section discusses the potential for risks occurring to non-target aquatic organisms as a result of the washoff associated with pirimiphos -methyl eartag uses. As discussed in Section 5.1 ., a qualitative evaluation of the amount of heads of cat tle resulting in a risk of concern to aquatic organisms is conducted ( Table 9 ) as opposed to deterministic risk quotients given the uncertainty
associated with the amount of simultaneous head of cattle treated. However, this section will place
these estimates into context with what is known re garding the density of cattle only at pasture use
sites. As discussed in Section 2 , feedlots would not be use site s where pirimiphos-methyl eartags are used. Risks to other non-targ et organisms associated with ea rtag use or general ecological risks associated with other use patterns are not el aborated in this section since no risks of concern are expected as discussed in Section 5.1.

-Page 27 of 49 Aquatic Exposure: Cattle Ear Tag Uses

As explained above, the amount of tr eated cattle resulting in a risk of concern to aquatic organisms is conducted ( Table 9 ), and these results can be placed into context with information regarding cattle populations at pasture sites where pirimi phos-methyl eartags are potentially used. This information on cattle populations can inform and discern the pote ntial number simultaneous heads
of cattle treated with the earta gs per use site. Ca ttle population data from USDA’s AgCensus (citation: http://www.agcensus.usda.gov/Publicati ons/2012/Online_Resour ces/Ag_Atlas_Maps/ Livestock_and_Animals/Liv estock,_Poultry_and_Other _Animals/12-M136-RGBDot1- largetext.pdf ) can be used for a preliminary estimate for cattle populations at use sites. Figure 1 shows that up to 200 head of cattle or more are common over a high density of farms nationwide. While some sites may possess over 200 head of cattle, it is not anticipated that many of such sites would possess more than 300 head of cattle, as th ese numbers of cattle are more likely associated with major regulated feedlots under EPA’ s NPDES program, which as discussed in Section 2

, feedlots would not be use sites where pirimiphos -methyl eartags are used. Furthermore, it is expected there would be many more sites less than 200 head of cattle, which would be the use sites where pirimiphos-methyl eartag treatments would be more likely. Sites that possess hundreds of heads of cattle would likely not possess the degree of horn fly and face fly infe stations for the same reasons that eartags would not be us ed at feedlots as discussed in Section 2

.

Figure 1. Dot density map showing approximate localities of farms keeping 200 or more head of cattle (Source: USDA AgCensus, 2012).

For non-listed and listed freshwater fish, Table 9 shows that much more head of cattle than numbers of cattle at farms which possess less than 300 head of cattle (not asso ciated with feedlots) would be required to result in adverse impacts on an acute basis. This is even the case if 100Page 28 of 49 percent of residues washo ff from eartags. Therefore, no advers e impacts would be expected with eartag use associated with freshwater fish.

For non-listed freshwat er invertebrates, Table 9 also shows that more head of cattle than the
number of cattle at non-feedlot fa rms would be required to result in acute adverse im pacts with 10 percent or less of residues washing off from feedlots. In many cases, it would not be expected that less than 10 percent of pirimiphos-methyl residue s would washoff and end up in water bodies for
resosons further discussed in Uncertainties Sectio n below. Therefore, adverse impacts would also not be expected with eartag use associated with non-listed freshwater invertebrates.

For listed freshwater invertebrate species, Table 9 conveys that between 40 – 200 cattle can potentially result in acute adve rse impacts with between 5 percen t down to 1 percent, respectively, of residues washing off into a water body. Howeve r, as explained above, while some non-feedlot farms may keep in excess of 200 head of cattle, pi rimiphos-methyl eartag use sites are not expected to be used at use sites keeping hundreds of head of cattle for reasons discussed in Section 2 , and is therefore expected that pirimiphos-methyl woul d be most commonly used at sites keeping less
than 40 head of cattle. Accord ing to the results presented in Table 9 , greater than 5 percent of residues being washed off from earta gs treating 40 head of cattle w ould lead to adverse impacts. However, it is expected that le ss than 5 percent of pirimiphos-methyl residues would wash off and end up in nearby water bodies for reasons discussed in the Uncertainties Section below. Therefore, in summary, no risks are anticipated for listed aqua tic invertebrate species with pirimiphos-methyl eartag use which is expected to be used mainly at use sites keeping small inventories of cattle.

Uncertainties and Limitations

 Acute Exposure of Pirimiphos-methyl and Wash off Fractions from Treated Cattle with Eartags

While the results presented in Table 9 provides a preliminary indicati on of the potential for risk associated pirimiphos-methyl eartags, the discus sion below identifies un certainties which exist regarding the fate and behavior of pirimiphos-m ethyl which are not explicitly captured in the analysis. The uncertainties in the analysis disc ussed below collectively pr ovides insights that a small portion of residues (l ess than 5 percent) ar e likely to washoff and end up in water bodies nearby use sites with pirimiphos-methyl eartags.

1. The number of cattle and respective washoff fr actions threshold for concern presented in
Table 9 is based on the assumption built into th e GENEEC model that pirimiphos-methyl residues on the ear tag washes off within two da ys of the treatment o ff and runs off into a static water body. While possible, the washoff fraction would be even less in reality when rainfall events are delayed from the onset of eartag treatments gi ven the potential for pirimiphos-methyl to degrade once it diffuses onto the skin of cattle.

2. Pirimiphos-methyl washoff and loadings in th e underlying environmen t about the use site is likely to be reduced by a number of factor s not captured in the analysis presented here. First, pirimiphos-methyl is semi-vol atile with a vapor pressure 1.1 x 10 -4 torr ( Table 1 ), but the analysis did not account for any loss of residues due to volatilization. Second, thisPage 29 of 49 assessment assumes that pirimiphos-methyl residues are not bound to the hide of treated
cattle while rainfall occurs. In reality, there is the possibili ty that residues bound to treated cattle would further reduce the loadings of pirimiphos-methyl in the environment as compared to the washoff scenario presented in the analysis. It s hould be noted, however,
that no data exists re garding the fate properties of pi rimiphos-methyl on cattle skin and
tissue.

Aside from washoff fractions potentially en ding up in water bodies, the main underlying uncertainty in this assessment is related to the amount of cattle that are tr eated simultaneously with pirimiphos-methyl by use site. Labels do not specif y limits for the amount of cattle that are treated with pirimiphos-methyl by use site. This uncertainty is addressed in the anal ysis by that it presents
an evaluation of the number of heads of treated cattle leading to adverse impacts ( i.e ., LOC exceedances) rather than deterministic risk quotient s based on a rigid exposure scenario based on
a fixed number of cattle treated with eartags . As explained in Section 5.2 , given the density of cattle at pasture use sites and that only a percen tage of those cattle would be treated, and that
infestations of horn flies and face flies are not likely to occur at large industrial-scale farms, the
amount of simultaneous heads of cattle treated with ceartags are expected to be less than 40 head

over many cases.

 Chronic Exposure with Pirimiphos-methyl Eartags and Associated Data Gaps

As mentioned previously, ther e are no chronic data availa ble for freshwater fish and
estuarine/marine fish and invertebrates as well as to sediment dwelling organisms. Environmental fate data are only available to show abiotic routes of degradation of parent pirimiphos-methyl when in water bodies. The available hydrolysis study sh ows that at pH 7, pare nt pirimiphos-methyl has a half-life of 79 days. The rate of photodegradation in water is much faster with a half-life of 0.2 days. However, light penetr ation through water may not be significant in many cases. No information is available to indicate how parent pirimiphos-methyl would break down in a biotic aquatic system. Therefore, pirimiphos-methyl was only assumed to degr ade abiotically (via hydrolysis and photolysis) and not biotically in the aquatic exposure an alysis discussed in Section
3.5 . Furthermore, consistent with other insect cont rol type of applications , there are uncertainties related to frequency of applications. Therefore, these uncertainties related to the rate of degradation in water and pirimiphos-methyl applica tion frequencies result in further uncertainties related to the duration of pirimiphos-methyl e xposures persisting in aquatic environments.

While chronic toxicity studies are longer duration studies th an acute studies, the intent of chronic studies is to expose organisms at different life stages than those of acute studies and below levels
known to be lethal in order to el icit effects on growth and reproducti on. It is anticipated due to the
toxic nature of OP insecticides that chronic ri sk cannot be precluded to all aquatic taxa.

The suite of submitted studies for pirimiphos-methyl reveals that there was a submitted chronic daphnia life cycle study submitted in 1991. This study (MRID 48411701) is not associated with a data evaluation record (DER) a nd therefore its results are descri bed here as they are not fully verified. Chronic daphnia were exposed to nomina l concentrations of control, solvent control, 0.025, 0.05, 0.1, 0.2, and 0.4 μg a.i/L. There was total (100%) mortality in the two highest treatment concentrations, and 70% mortality in the 0.1 μg a.i/L treatment concentration. TherePage 30 of 49 were no significant (p<0.05) reducti ons in length at all treatmen t concentrations (excluding the ones with 100% mortality for which no data were available). Additionally, there was a significant
reduction in the total number of live young as compar ed to the control in th e three highest treatment concentrations. The NOAEC for this study (bas ed on live number of young and mortality) was therefore set at 0.05 μg a.i/L. As stated previousl y, these results are not st atistically verified and
therefore cannot be considered final but can be used qualitatively to indicate pirimiphos-methyl exposure appears to be an order of magnitude mo re toxic on a chronic basi s as compared to an
acute basis.

In extending the analysis for chronic data as it was presented for acute impacts in Table 9 for all percent washoff scenarios assessed (1, 5, 10, 20, a nd 100%), the number of h eads of cattle within a typical use site would result in similar amounts of treated cattle triggering risks of concern for aquatic invertebrates. Furthermore, similar wa shoff fractions for cattle densities presented in
Table 11 would result in risk of co ncerns for aquatic invertebra tes considering the available chronic toxicity data. Therefore, given these si milar outcomes, the above justification discounting risks of concern for acute aquatic invertebra tes would also apply to chronic impacts.

 Bioaccumulation of Pirimiphos-methyl

As indicated by available environmental fate data, pirimiphos-methyl has the potential to bioaccumulate in the tissues of organisms based on its Log K OW of 4.2. This is further corroborated by the bioconcentration factor (BCF) being estimated as 274X (SRC and EpiSuite, WSKOW v.1.42). While this potential exists, it is unclea r, due to a lack of a registrant submitted fish BCF study, how quickly and to what extent pirimip hos-methyl residues are depurated from living tissues. Therefore, given the potential for piri miphos-methyl’s offsite transport to water bodies and its hydrophobic properties, pirimiphos-methyl has the potential to bioaccumulate in aquatic organisms like fish. The extent to which the c onsumption of those contaminated fish by birds will pose a risk is uncertain as a propensity to bioacc umulate does not necessarily indicate that those
residues will be available in the ti ssues for days or weeks later.

Although GENEEC does not provide pore water EEC estimates, a run of the KABAM model using water column values provided by GENEEC is us ed to evaluate piscivorous birds including sandpipers, rails, and small osprey consumin g pirimiphos-methyl contaminated fish. When assuming 20% washoff and subsequent runoff from 300 head of cattle getting treated at the same time, the highest RQ, occurring with dose-base d risk to sandpipers eating pirimiphos-methyl contaminated fish remains, is below the listed species LOC ( RQ < 0.006 ). Furthermore, there were no risk findings above the LOC for dos e or dietary-based risk to mammals.

 Terrestrial Exposure

The exposure pathway for terrestrial organisms was determined to be minimal for the seed treatment stored grain use in the problem fo rmulation of pirimiphos-methyl. Exposure to terrestrial organisms via the ear tag use was also determined to be minimal. Although acute and subacute dietary studies for birds indicate that pirimiphos-methyl is moderately to highly toxic to birds on both an acute oral and subacute dietary basis, and available data determined what doses
and what concentrations would elic it lethal effects as well as clin ical signs of to xicity, it isPage 31 of 49 unknown as to the extent of pirimi phos-methyl that would be availabl e to terrestrial organisms. As mentioned previously th e scenario of ear tags falling off he ads of cattle was determined to not be likely and will therefore not be further discussed. That leaves few plausible scenarios as to how
birds and other mammals would be exposed to pirimiphos-methyl resul ting from this ear tag use. The lack of reported wildlife incidents to bird s and other mammals for pirimiphos-methyl further suggest this pathway is potentia lly incomplete although the literatu re indicates birds and mammals may be an important vector for diseas es transmission in cattle feed lots.

Pirimiphos-methyl is highly toxic to adult honey bees on an acute co ntact and oral basis as would be anticipated from an OP insecticide, although th ere are no data to charac terize the t oxicity to honey bee larvae. Additionally, ther e is an uncerta inty as to what exte nt honey bees would be exposed to pirimiphos-methyl residu es as cattle feedlots would likely no t serve as attractive areas for forage.

 Ecological Effects Data Gaps

There are only three studies available to characte rize the acute toxicity of pirimiphos-methyl to freshwater fish and invertebrates. The analysis presented above indicates that there is a plausible exposure pathway that can exist with at worst a 0.03% washoff threshold that is needed to cause impacts to listed freshwater invertebrates. Wh ile data are not available for estuarine/marine invertebrates, risk to this taxa cannot be pr ecluded as washoff fractions could reach these environments, and as pirimiphos-methyl is an orga nophosphate insecticide, le thality to this taxa can be expected based on the extensive da ta set of other active ingredients.

There are also no data present to characterize the toxicity of pirimiphos-methyl to sediment dwelling aquatic inve rtebrates. Environmental fate data indicate pirimiphos-methyl has some propensity to bind to sediment as evidenced by its hydrophobic nature as evidenced by a Log K OW of 4.2. Although no data are presen t, the case for the presence of risk to freshwater and
estuarine/marine sediment dwelli ng invertebrates can be made ba sed on the like lihood of some washoff of pirimiphos-methyl residues into aquatic systems and its propensity to bind to organic carbon. Furthermore, water column freshwater inve rtebrates were observed to be very sensitive to pirimiphos-methyl exposure as expected from an OP insecticide and so similar toxicity can be presumed to benthic invertebrates given that this exposure pathway cannot be precluded.

It was previously stated that no ch ronic toxicity data are available for birds. In a review of the submitted studies for pirimiphos-methyl, a stud y entitled “Egg Production and Hatchability Following Inclusion of Pirimiphos-methyl at Various Levels in the Diet of the Laying Hen,” was found but was not associated with any DER. Theref ore, the results of this study will be discussed here in the uncertainties section as they are not verified and therefore can not be considered final
at this time. This stud y (MRID 48361701) was conducted in 1978, which was prior to the availability of the current OC SPP 850.2300 avian reproduction study gu ideline. In the study, birds (species not identified) were expos ed to pirimiphos-methyl concentratio ns in the diet of control, 4, 12, and 40 ppm. There were no treatment related mo rtalities that were observed nor were there any clinical signs of toxicity. There was no significant (p<0.05) reduc tion in food consumption
that was observed in the treatm ent groups as compared to cont rol although food consumption in the treatment groups were generall y less than that of control. During the recovery period, foodPage 32 of 49 consumption between the control and treatment gr oups was similar. There were no significant (p<0.05) reductions in e gg production, fertility, and hatchabi lity in the treatment groups as compared to control. The NOAEC for this stud y was therefore determined to be 40 ppm. As stated previously, it is not expect ed that birds would be subjected to exposure of pirimiphos-methyl resulting from the cattle eartag use.

 Risk to Aquatic and Terrestrial Plants

There is no data available to ch aracterize the toxicity of pirimiphos -methyl to terrestrial and aquatic vascular and non-vascular plants. For terrestrial plants, exposure to this taxa would be limited for both stored grain seed treatment as well as for the ear tag use. As there are no spray uses for pirimiphos-methyl, non-target terrestr ial plants would only be exposed via runoff from a feedlot.
Given the mode of action of this chemical is the i nhibition of cholinesterase, toxic effects to plants are not anticipated but there is uncertainty in toxi city to plants being medi ated by some other mode of action. Furthermore, there are no reported eco logical incidents with terrestrial plants and pirimiphos-methyl that provide some suggesti on that this exposure pathway is potentially complete.

Risk to aquatic plants is a bigge r uncertainty given that this e xposure pathway would be complete via washoff from ear tags and the f act that there is no data availabl e to characterize the toxicity to aquatic vascular and non-vascular plants.



## 6. Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews nu merous studies to a ssess potential adverse outcomes from exposure to chemicals. Collectiv ely, these studies include acute, subchronic and chronic toxicity, including assessments of carcinogenicity, neurotox icity, developmental, reproductive, and general or systemic toxicit y. These studies include endpoints which may be susceptible to endocrine influe nce, including effects on endocr ine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pregnanc y rates, reproductive loss, and sex ratios in offspring. For ecolo gical hazard assessments, EPA ev aluates acute tests and chronic studies that assess growth, devel opmental and reproductive effects in different taxonomic groups.

EPA has developed the EDSP to determine whether certain substances (inc luding pesticide active and other ingredients) may have an effect in humans or wildlife si milar to an effect produced by a “naturally occurring estrogen, or ot her such endocrine effects as the Administrator may designate.” The EDSP employs a two-tiered approach to maki ng the statutorily required determinations. Tier 1 consists of a battery of 11 scr eening assays to identify the potenti al of a chemical substance to interact with the estrogen, androge n, or thyroid (E, A, or T) horm onal 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 availabl e data. Tier 2 testing is designed to identify any adverse endocrine-related effects caused by th e substance, and esta blish a dose-response relationship between the dose a nd the E, A, or T effect.Page 33 of 49 Under FFDCA section 408(p), the Ag ency must screen all pesticid e chemicals. Between October 2009 and February 2010, EPA issued test orders/dat a call-ins for th e first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert ingredient s. A second list of chemicals identified for EDSP screening was published on June 14, 2013 10 and includes some pesticides scheduled for registration review and chemicals found in water

. Neither of these lists should be
construed as a list of known or likely endocrine disruptors.

Pirimiphos-methyl is not among the group of 58 pestic ide active ingredients receiving EDSP test
orders. For information on the status of the orders issued under the EDSP for each chemical, please visit our website at http://www.epa.gov/endo/ and click on the "Status of EDSP Orders/DCIs" in the Highlights Box. Additiona l information on the EDSP, including the policies and procedures, the list of 67 chemicals, the test guidelines and the Tier 1 screening battery, can
also be found at this website.



## 7. Federally Threatened and Endangered (Listed) Species of
Concern

Based on this screening-level assessment, there are potential risks of direct effects to listed birds, mammals, freshwater and estu arine/marine fish, invertebrate s, and sediment dwelling invertebrates, aquatic vasc ular plants, and terrestr ial dicot plant species fr om the use of pirimiphosmethyl on some of its registered use sites. Listed species of birds, mammals, freshwater and estuarine/marine fish and invertebrate taxa may al so be affected through indirect effects because of the potential direct effects on listed and non-lis ted species. Potential direct effects on listed birds, mammals, freshwater and estuarine/marine fish, invertebrates, and sediment dwelling invertebrates from the use of pirimiphos-methyl ma y be associated with modification of Primary Constituent Elements (PCEs) of designated critical habitats, where such designations have been made. However, at this current stage of the Registration Review pr ocess, it is premature to make effects determinations for listed species until furthe r scientific analysis and refinements are conducted, based on recommendations received fr om the National Academy of Sciences’ (NAS) National Research Council (NRC) April 2013 report, available at http://www.nap.edu/catal og.php?record_id=18344. The NAS report outlines recommendations on specific scientific and technical issues related to the development of pesticide risk assessments that are compliant with the En dangered Species Act (ESA) and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

The EPA along with the U.S. Fish & Wildlife Se rvice (USFWS), the National Marine Fisheries Service (NMFS) (collectively, the Services), a nd the U.S. Department of Agriculture (USDA), released a summary of their implementation plan for assessing risks of pestic ides to listed species ahead of the stakeholder workshop held on Nove mber 15, 2013. This plan was developed in response to the NAS’ recommendations, including a common approach to risk assessment as a way of addressing scientific di fferences between EPA and the Se rvices. During the workshop, the agencies received feedback from the public on the interim scientific approaches that were

10 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of

chemicals.Page 34 of 49 developed as part of the initial implementati on of the NAS recommendations. These approaches will be jointly implemented and vetted as part of a phased iterative process. Once fully vetted, EPA will further refine the listed species effects determination portion of this risk assessment.

To make effects determinations for individual listed species, us eful refinements may include, but are not limited to, analyses of: 1) more detaile d, species-specific ecological and biological data; 2) more detailed and accurate information on pirimi phos-methyl use patterns; and 3) sub-county level spatial proximity data for the co-occurrence of po tential effects areas and listed species and any designated critical habitat. Examples of such refinements are described below.

EFED is currently developing tools that are exp ected to further refine the assessment and are designed to support effects determinations for individual federally lis ted species and their designated critical habitats (where applicable ). Scientific information obtained from the Services, and other reliable sources is being co llated by EFED to address all currently listed species. This information is being stored in an Office of Pesticide Programs (OPP) Pesticide Registration Information SysteM (PRISM) listed species knowledgebase. The listed species knowledgebase consists of an information repos itory that houses biological and behavioral
information relevant to individua l species (e.g., habitat, diet, and life history, including specific temporal and spatial associations) and a documen t repository that contains supporting documents ( e.g. , USFWS recovery plans) a nd electronic information ( e.g. , GIS data files). For terrestrial taxa, biological information re levant to the assessment ( e.g. , diet and body weight) will be used to parameterize exposure estimates using a method c onsistent with currently used methods in the
T-REX and T-HERPS models.

Refinements will also include mo re detailed analyses of the re gistered uses and specific use patterns that result in either “Likely to Advers ely Affect” (LAA) or “Not Likely to Adversely Affect” (NLAA) determinations for federally list ed species. The analyses may include more information on where, when, and how pirimiphos-met hyl is used on all use sites. Actual usage data (when available) and national land-cover da tasets that indicate potential use sites [ e.g. , National Land Cover Dataset (NLCD), Cropland Da ta Layer (CDL)] may be used to support a more refined analysis of where pirimiphos-methyl is reasonably expected to be used. Similarly, refinements on the timing of applications and a mo re in-depth exploration of agronomic practices for pirimiphos-methyl may be includ ed as part of the refinement.

The refinements based on individu al species data; additional, detailed usage information, when available; and recommendations from the NRC re port are expected to he lp to more accurately identify potential areas of effect and to better inform effects and habitat determinations for listed species and any designate d critical habitats.



### 7.1 Action Area

For listed species assessment purposes, the action area is considered to be the area affected directly or indirectly by pirimiphos-methyl use and not merely the immediate area where pirimiphosmethyl is applied. At the initial screening-le vel, the risk assessment considers broadly described taxonomic groups and conservatively estimates expos ure for organisms that are co-located with the pesticide treatment area. This means that te rrestrial plants and wildlife are assumed to bePage 35 of 49 located on or adjacent to the treated site and a quatic organisms are assumed to be located in a surface water body adjacent to the tr eated site, except in the case of direct application to aquatic
habitat.

3 No data are available on terrestrial and aquatic plants wh ich may serve as food items for all terrestrial and aquatic taxa. It is unclear of the toxicity of pirimiphos-methyl to these taxa and in the case of terrestrial plants, as to whether a complete exposure pathway would exist given the absence of spray uses of pirimiphos-methyl.

4 Although no toxicity data are available, the acute and chro nic toxicity to these taxa to OP insecticides is well established as well as the fact that pirimiphos-methyl is stable to aerobic aquatic metabolism.



### 7.2 Listed Species Occurrence Associated with Registered
Uses

The screening-level risk asse ssment for pirimiphos-methyl assumes that it may be applied nationwide, including U.S. territo ries and possessions. Therefore, no federally listed species are excluded from the screening level an alyses, unless otherwise indicated ( e.g. , if only listed due to Similarity of Appearance to another listed speci es). A spatial co-occurrence analysis that compares the best available da ta regarding pirimiphos-methyl pot ential and documented use areas and listed species occurrence is needed to more explicitly address potential risk to listed species of concern. The Agency has reque sted data to support this analysis from the Federal Endangered Species Task Force (FESTF).



## 8. Conclusions

There are many uncertainties related to pirimiphos -methyl, several of whic h were detailed in the Risk Description Section of this assessment. Th ese uncertainties mainly relate to environmental fate and ecological effects data gaps, as well as the unconventional nature of the uses associated with pirimiphos-methyl where exposure cannot be estimated in a conventional manner using standard EFED models. However, given the highl y conservative nature of the assumptions for environmental loading as provided in this assess ment, and that small cattle operations are where pirimiphos-methyl eartags are only used, exposure is not expected to occu r at levels exceeding levels of concern to aquatic or terrestrial organisms.Page 36 of 49 

## 9. References

Alabama (State of), Alabama A & M and Auburn Universities. Fly Control for Alabama Cattle Opearions. Available online at http://www.ag.auburn.edu/ enpl/directory/faculty /hu/documents/ANR-2083-VetFlyControl-20140211.pdf Accessed
December 2015

CFR 40. 2007. Code of Federal Regulati ons 40 Parts 150 to 189. Protection of the Environment. U.S. Government Printing Office.

Charizopoulos E. and Papadopoulou-Mourkidou, E. 1999. Environ Sci. Technol., 33: 2363-

2368.

Close M.E. 1999. New Zealand J Mari ne Freshwater Res., 27: 267-273.

Cremlyn, R.J. 1991. Agrochemicals: Preparati on and Mode of Action. p. 121 - 124. John Wiley and Sons. New York, NY.

European Food Safety Authority. 2005. Conclusion regarding the peer review of the pesticide
risk assessment of the activ e substance pirimiphos-methyl. 44, 1-53. Available online at http://www.efsa.europa.eu/cs/BlobServer/ PRAPER_Conclusion/praper_concl_sr44_piri miphos-methyl_en1.pdf?ssbinary=true Accessed November 2014.

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the EPA food-chain (Kenaga) nomogram, an instru ment for estimating pesticide residues on plants. Environ. Tox. Chem. 13:1383-1391.

Hoerger, F. and E. E. Kenaga, 1972. Pesticide Re sidues on Plants: Correlation of Representative Data as a Basis for Estimation of their Magnit ude in the Environment. In F. Coulston and F. Korte, eds., Environmental Quality and Safety: Chemistry, Toxicology, and Technology, Georg Thieme Publ., Stuttg art, West Germany, pp. 9-28.

Kentucky (State of), University of Kentucky. Horn Flies and Cattle. Available online at http://www2.ca.uky.edu/entomology/entfacts/ef509.asp Accessed December 2015.

Kizil, U. and Lindley J., 2002. Feedlot Runo ff and Manure Manageme nt Modeling. United States Department of Agricu lture State Water Resources Research Institute, 2002 State Water Projects. Available online at http://water.usgs.gov/wr ri/02grants/prog-complreports/2002ND7B.pdf . Accessed November 2014.

Mayer, F.; Ellersieck, M. 1986. Manual of Acute Toxicity: In terpretation and Data Base 410 Chemicals and 66 Species of Fresh-Water Animals . US Fish & Wildlife Service; Resource Publication (160): 579 p.Page 37 of 49 Mississippi (State of), Mississi ppi State University. Horn Flies on Cattle: Biology and Management. Available on-line at http://store.msuextension.org/publicati ons/AgandNaturalResources/MT200912AG.pdf
Accessed December 2015.

Nebraska (State of), University of Nebraska. Controlling Flies on Pastured Cattle in Nebraska.
Available on-line: http://newsroom.unl.edu/announce/beef/3199/18423 Accessed 2015.

Syngenta. Actellic 50EC Environmental Info rmation. Cambridge, UK. Available online athttp://www.syngentacrop.co.uk/pdfs/products/Actellic50E C_uk_environmental_information.pdf

. Accessed November 2014.

Syngenta. Actellic 50EC Safety Data. Cambridge, UK. Available online at http://www.syngenta-crop.co.uk/pdfs/pr oducts/Actellic50EC_uk_safety_data.pdf

. Accessed November 2014.

U.S. Department of Agriculture (USDA). 2011. Feedlot 2011 Report, Part I: Management
Practices on US Feedlots w ith a Capacity of 1,000 or More Head. United States Department of Agriculture. Available online at: . http://www.aphis.usda.gov/animal_health/n ahms/feedlot/downloads/feedlot2011/Feed11 _dr_PartI.pdfAccessed Accesed Novermber 2014.

USDA, Economic Research Service Briefing Room. 2014. United States Department of Agriculture. Available online at: http://www.ars.usda .gov/IS/pr/2005/051216.htm

. Accessed November 2014.

USDA. 2000. National Agricultural Census – Ag ricultural Chemical Usage – 1999 Cattle and Cattle Facilities. United States Department of Agriculture National Agricultural Statistics Service, Washington, DC.

U.S. Environmental Protection Agency (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 . Accessed November 2014.

USEPA. 2002. Guidance for Selecting Input Parame ters in Modeling the E nvironmental Fate and Transport of Pesticides, Version II. US Environmental Protection Agency, Washington
DC. Online at: http://www.epa.gov/oppefed1/mode ls water/input_guidance2_28_02.htm

. Accessed November 2014.

USEPA. 2004. Overview of the Ecological Risk Assessment Process in th e Office of Pesticide Programs. U.S. Environmental Protection Ag ency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington DC. January 23, 2004.Page 38 of 49 USEPA. 2006. Reregistration Eligibility Decision (IRED): Pirimi phos Methyl. U.S. Environmental Protection Agency, Office of Pesticide Programs, Washington, DC. July,

2006.

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and Conference Activities Under Section 7 of the Endangered Sp ecies Act. Final Draft.
March 1998.



## Appendix A. Environmental Fate and Ecological Effects Data for Pirimiphos-methyl

161-1 Hydrolysis

MRID Citation Reference

135353 ICI Americas, Inc. (1977) Actellic 7E Insecticide: ?Product Chem- istry|.(Compilation; unpublished study received Dec 1, 1978 under 10182-EX15; CDL:097668-A)

135356 Easton, C.; Seaman, D. (1970) Pyri midines: Effect of pH on the Hydrolysis of PP 211 and PP 511: Ref. No. AR 2175 A. (Unpub- lished study received Dec 1, 1978 under 10182-EX-15; prepared by Plant Protection Ltd., Eng., submitted by ICI Americas, Inc ., Wilmington, DE; CDL:097680-A)

135357 Bowker, D.; Hughes, H. (1974) Pirimiphos-methyl: Fate in Water: AR 2516A. (Unpublished study received Dec 1, 1978 under 10182-EX- 15; prepared by Plant Protection Ltd., Eng ., submitted by ICI Americas, Inc., Wilmington, DE; CDL:097680-B)

42982401 Hall, B. (1993) The Determination of the Hydrolytic Stability of (carbon 14)- Pirimiphos-Methyl: Lab Project Number: 9545: 382403. Unpublished study prepared by Inveresk Research International. 112 p.

43177601 Hall, B.; Williams, S. (1994) Report Amendment to Study Report (MRID
# 42982401 ): The Determination of the Hy drolytic Stability of (carbon 14)-Page 39 of 49 Pirimiphos-Methyl: Lab Project Number: 382403: WECO-9206: 9545 ADDENDUM. Unpublished study prep ared by Inveresk Research International. 37 p.



### 162-1 Aerobic soil metabolism

MRID Citation Reference

135358 Arnold, D.; Hill, I.; Harvey, B.; et al. (1976) Pirimiphos-methyl: Degradation of the Pesticide in Soil under Laboratory Condi- tions: AR 2656 A. (Unpublished study received Dec 1, 1978 under 10182-EX-15; prepared by Imperial Chemical Industries, Ltd., E ng., submitted by ICI Americas, Inc., Wilmington, DE; CDL: 097680-D)



## 163-1 Leach/adsorption/desorption

MRID Citation Reference

68104 Riley, D.; Stevens, J.E. (1975) Pirimiphos-ethyl: Leaching in Soil: AR 2592A. (Unpublished study received Dec 17, 1976 under 10182-9; prepared by Plant Protection Ltd., submitted by ICI Americas, Inc., Wilmington, Del.; CDL:227314-W)

48355602 Schocken, M. (2010) Acceptability of Foreign Soils Used in a PirimiphosMethyl Batch Equilibrium Study. Pr oject Number: 2010/P/3. Unpublished study prepared by Schocken Consulting, LLC. 23 p.

48355601 Hartfree, Y.; Muller, K.; Lane, M. (2011) Pirimiphos-Methyl: Adsorption and Desorption in Soil. Project Number: RJ1461B. Unpublished study prepared by Jealott's H ill Res. Station. 70 p.



## 164-1 Terrestrial field dissipation

MRID Citation Reference

154033 Heuer, B.; Birk, Y.; Yaron, B. (1976) Effect of phosphatases on the persistence of organophosphorus insecticides in soil and water. Journal of Agric. Food Chem. 24(3):611-614.



## Non-Guideline Studies

MRID Citation Reference

44053301 Hathorn, S. (1996) Nu-Gro Insecticide S.P... : Response to EPA Chemis try Branch Review ofPage 40 of 49 Data Requirements to Defend the Use on Co rn Seed and Sorghum Seed for Controlling Storage Pests: Lab Project Number: DEFENSE OF BULK/BAGGED SEED USE RESPONSE. Unpublished study prepared by Co mpliance Services Inte rnational. 129 p.

44584702 Sielaty, R. (1998) Pirimiphos-Methyl in vitr o Absorption from a 500g/l EC Formulation through Rat Epidermis: Lab Project Number: WECO- 9802: JV1483: CTL/P/5239. Unpublished study prepared by Compliance Services International. 27 p.

45932601 Wo, C. (2003) UV/Visible Absorption: Pirimi phos-methyl Technical: Lab Project Number: 13425: P805. Unpublished study prepared by Product Safety Labs. 13 p. {OPPTS 830.7050}

46173801 Lake, R. (2004) Product Chemistry: Stor age Stability and Corrosion Characteristics:
Dominator Insecticide Ear Tags. Project Number: 071 /006, EXP/071/006, EXM/071/004. Unpublished study prepared by Exygen Research. 56 p



## 71-1 Avian Single Dose Oral Toxicity

MRID Citation Reference

41311001 Ross, D.; Roberts, N.; Fairley, C. (1979) The Acute Oral Toxicity (LD50) of Pirimiphos Methyl to the Mallard Duck: Lab Project Number: CTL/C/726. Unpublished study prepared by Imperial Chemical Industries Ltd., Huntingdon Research Centre. 18 p.

43442101 Campbell, S.; Beavers, J. (1994) Pi rimiphos-Methyl: An Acute Oral Toxicity Study With the Northern Bobwhite: Lab Project Number: 94041-WECO: 134-103. Unpublished study prepared by W ildlife International Ltd. 59 p.

80742 Gage, 1971. Oral with Green finch, Pigeon, and Japanese quail.
Accession 097679.



## 71-2 Avian Dietary Toxicity

MRID Citation Reference

42037001 Hakin, B.; Johnson, A.; Anderson, A.; et al. (1990) Pirimiphos- Methyl Dietary Toxicity (LD50) to the Bobw hite Quail: Lab Proj- ect Number: JAN 244/90755. Unpublished study prepar ed by Hunt- ingdon Research Centre, Ltd. 30 p.

103923 Parkinson, G.; Banham, P. (1971) Pirimiphos-methyl (PP 511): Avian Toxicity: Report No. HO/1H/R/329. (Unpublished study received Dec 1, 1978 under 10182-EX-15; prepared by Imperial Chemical Industries, Ltd., Eng., submitted by ICI Americas, In c., Wilmington, DE; CDL:097679-B)

107422 Fink, R. (1974) Final Report: Eight-day Dietary LC50--Mallard Ducks: ?Technical Pirimiphos Methyl|: Project No. 123-102. (Unpublished study received Dec 1, 1978 under 10182-EX-15; prepared by Truslow Farms, Inc., submitted by ICI Americas, In c., Wilmington, DE; CDL:097679-D)

107423 Fink, R. (1974) Final Report: Ei ght-day Dietary LC50--Bobwhite Quail:Page 41 of 49 ?Technical Pirimiphos Methyl|: Project No. 123-101. (Unpublished study received Dec 1, 1978 under 10182-EX-15; prepared by Truslow Farms, Inc., submitted by ICI Americas, In c., Wilmington, DE; CDL:097679-E)



## 72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference

92147004 Smyth, D.; Hill, R. (1990) ICI Am ericas Inc. Phase 3 Summary of MRID 00103924. Pirimiphos-methyl (PP511): Dete rmination of the Acute Toxicity to Rainbow Trout (Salmo gairdneri): Report No. BL/B/1868; Study No. D608/A. Prepared by ICI BRIXHAM LABORATORY. 12 p.

103925 Bluegill Acute Brixham Laboratories, 1975

103925 Rainbow Acute Brixham Laboratories, 1975

103924 Hill, R. (1978) Determination of t he Acute Toxicity of Pirimiphos- methyl to Rainbow Trout ...: BL/B/1868. (Unpublished study received Dec 1, 1978 under 10182-EX-15; prepared by Imperial Chemical Industries, Ltd., Eng., submitted by ICI Americas, Inc ., Wilmington, DE; CDL:097679-F)

108078 Hill, R. (1978) Determination of t he Acute Toxicity of Pirimiphos- methyl to Fathead Minnow ...: BL/B/1873. (Unpubl ished study rece ived Dec 1, 1978 under 10182-EX-15; prepared by Imperial Chemical Industries, Ltd., Eng., submitted by ICI Americas, Inc ., Wilmington, DE; CDL:097679-G)



## 72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

92147005 Hamer, M. (1990) ICI Americas Inc. Phase 3 Summary of MRID 00103926. Pirimiphos-methyl: Toxicity to First Instar Daphnia magna: Report No. TMJ1411B. Prepared by ICI AGROCHEMICALS. 13 p.

103926 Pirimiphos-methyl: Toxicity to First Instar Daphnia magna: Report No. TMJ1411B. Prepared by ICI AGROCHEMICALS. 13 p. Test includes technical and formulation testing



## 850.1300 Chronic Toxicity Freshwater Invertebrates

MRID Citation

48417101 Rapley, J.; Hamer, M. (1991) Pirimiphos-Methyl: Chronic Toxicity to Daphnia magna. Project Number: RJ0940B. Unpublished study prepared by ICI Agrochemicals. 29 p.



## 141-1 Honeybee Acute Toxicity Testing

MRID Citation ReferencePage 42 of 49 05001991 Stevenson, 1978. Bee studie s conducted at Univ. of California



### 142-3 Simulated or Actual Field Testing

MRID Citation Reference

43717 Smith, F.D. (1976) PP557: Effect s on Predatory and Parasitic Arthropods: Report Series TMJ 1283 B. (Unpublished study received Dec 2, 1976 under 10182-EX-3; prepared by Imperial Chemi- cal Industries, Ltd., submitted by ICI Americas, Inc., Wilmin gton, Del.; CDL:095996-G)

50011991 Stevenson, J.H. (1976). The acut e toxicity of unformulated pesticides to worker honey bees (Apis mellifera L.). Plant Pathol. 27(1): 38-40.



### Non-Guideline Study

MRID Citation Reference

46364315 Brealey, C.; Walker, C.; Baldwin, B. (1980) A-Esterase Activities in Relation to the Differential Toxicity of Pirimiphos-Methyl to Birds and
Mammals. Pestic. Sci. 11: 546-554.



## Appendix B. Aquatic Exposure Modeling Summary

Figure B-1. GENEEC model run fo r pirimiphos-methyl eartag uses.

RUN No. 1 FOR Pirimiphos-methy ON eartags * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE NO-SPRAY INCORP
ONE(MULT) INTERVAL Kd (PPM ) (%DRIFT) ZONE(FT) (IN)

-------------------------------------------------------------------- 1.000( 1.000) 1 1 49.0 8.6 GRANUL( 0.0) 0.0 0.0

FIELD AND STANDARD POND HALFLIFE VALUES (DAYS)

-------------------------------------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINEDPage 43 of 49 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND)

-------------------------------------------------------------------- 39.10 2 198.00 0.20- 24.80 0.00 22.04

GENERIC EECs (IN MICROGRAMS/LITER (PPB)) Version 2.0 Aug 1, 2001

-------------------------------------------------------------------- PEAK MAX 4 DAY MAX 21 DAY MAX 60 DAY MAX 90 DAY

GEEC AVG GEEC AVG GEEC AVG GEEC AVG GEEC

-------------------------------------------------------------------- 7.26 6.97 5.60 3.62 2.75

Notes:
1. Please refer to Table 2 for explanation and rationale for input parameter values.

2. Modeling conducted normalized to an applicati on rate of 1 lb. a.i./A. Results shown in Tables 8 and 9 are derived from linearly scaling the peak EEC shown in this figure to the application rates per head of cattle
shown in Table 8 for each washoff fraction.Page 44 of 49 

## Appendix C. Inhalation Exposure Screening Evaluation

Figure C-1. STIR run for pirimiphos-me thyl eartag and seed treatment uses.

This tool is designed to provide the risk assessor with a rapid method for determining the potential
significance of the inhalation exposure route to birds and mammals in a risk assessment.

Input

Application and Chemical Information

Enter Chemical Name Pirimiphos-methyl

Enter Chemical Use Eartag Is the Application a Spray? (enter y or n) n If Spray What Type (enter ground or air) ground Enter Chemical Molecular Weight (g/mole) 305 Enter Chemical Vapor Pressure (mmHg) 1.10E-04 Enter Application Rate (lb a.i./acre)

Toxicity Properties

Bird

Enter Lowest Bird Oral LD 50 (mg/kg bw) 40 Enter Mineau Scaling Factor 1.15 Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD 50 (mg/kg bw) 2400

Enter Lowest Rat Inhalation LC 50 (mg/L) 5.04 Duration of Rat Inhalation Study (hrs) 4 Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )
Maximum Vapor Concentration in Air at Saturation (mg/m 3 ) 1.81E+00 Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.27E-01

Adjusted Inhalation LD 50 4.68E-01

Ratio of Vapor Dose to Adjusted Inhalation LD 50 4.85E-01 Proceed to Refinements Maximum Post-treatment Spray Inhalation Dose (mg/kg) not applicable

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD 50 not applicable not applicable

Results Mammalian (0.015 kg )
Maximum Vapor Concentration in Air at Saturation (mg/m 3 ) 1.81E+00 Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.85E-01

Adjusted Inhalation LD 50 3.00E+02

Ratio of Vapor Dose to Adjusted Inhalation LD 50 9.51E-04 Exposure not Likely Significant Maximum Post-treatment Spray Inhalation Dose (mg/kg) not applicable

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD 50 not applicable not applicablePage 45 of 49Figure C-2. HED Tier 1 Air Exposure Model run for pirimiphos-methyl eartag and seed treatment uses.* Equivalent application rate calculated assuming 8,000 head of cattle present on 10 ha feedlot.Pirimiphos‐MethylVaporPressure(Pa) 1.10E‐0410 20 40 60 80 120Solubility(mg/L) 8.6 Baresoil 0 0 0 0 0 N/AKoc(ml/g) 3329 Colecrop 0 0 0 0 0 N/ABaresoil Foliarappstocrops Rowcrop 0 0 0 0 0 0Applicationrate(lbsai/A) 2.744 NA Orchard10 0 0 0 0 N/AHourlyFluxRate(μg/m2‐s) 8.10E‐02 2.61E‐02Applicationtiming WorstcaseAveragingtimeforconcentration(hours) 11InhalationPOD(μg/m3) 930.75UF(unitless) 10Concentrationofconcern(μg/m3) 93Notes:1.AirflowthroughanorchardiscomplexandAERSCREENdoesnottakethiscomplexityintoaccount.Orchardvaluesshouldbecharacterizedappropriately.2.Areasshadedingreenareforuserinput.Theusershouldnotenterinformationintheareasshadedinred.3."Durationofmaximumemission"shouldbelessthanorequalto24hours.DistancetoCOC(m)FieldSize(acres)CropTypePage 46 of 49Figure C-3. HED Tier 1 Air Exposure Model estimated exposure concentrations for vaporphase pirimiphos-methyl.

Notes:
1. Maximum EEC shown in yellow shading. Distance (m) 10 20 40 60 80

0 10.26 17.34 26.68 33.12 38.46

5 10.56 17.64 26.92 33.33 38.73

10 10.85 17.94 27.16 33.60 38.99

15 11.14 18.24 27.40 33.86 39.26

20 11.43 18.53 27.67 34.13 39.53

25 11.73 18.83 27.96 34.40 39.78

50 13.24 20.38 29.39 35.69 40.91

75 14.47 21.44 30.54 37.27 42.28

100 15.25 22.06 31.09 37.84 43.21

125 15.66 22.37 31.48 38.08 43.31

150 15.80 22.54 31.62 38.08 43.19

175 15.83 22.61 31.55 37.89 42.96

200 15.80 22.53 31.34 37.57 43.26

225 15.71 22.34 31.06 37.76 43.44

250 15.55 22.08 30.93 37.88 43.48

275 15.33 21.77 31.01 37.87 43.41

300 15.08 21.64 30.98 37.78 43.25

325 14.86 21.63 30.88 37.60 43.02

350 14.77 21.55 30.73 37.37 42.79

375 14.71 21.43 30.52 37.15 42.53

400 14.60 21.27 30.29 36.89 42.23

425 14.48 21.09 30.05 36.61 41.89

450 14.33 20.89 29.82 36.30 41.54

475 14.17 20.70 29.55 35.97 41.16

500 14.00 20.50 29.26 35.63 40.77 Bare soilPage 47 of 49 

## Appendix D. Drinking Water Exposure Screening Evaluation

Table C-1. SIP model run for pirimiphos-methyl.

Parameter Value

Chemical name Pirimiphos-methyl
Solubility (in water at 25 o C; mg/L) 8.6

Mammalian LD 50 (mg/kg-bw) 2400 Mammalian test species laboratory rat Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg-bw) 0.87 Mammalian test species laboratory rat Body weight (g) of "other" mammalian species

Avian LD 50 (mg/kg-bw) 40 Avian test species northern bobwhite quail Body weight (g) of "other" avian species Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) Bobwhite quail NOAEC (mg/kg-diet) NOAEC (mg/kg-diet) for other bird species Body weight (g) of other avian species NOAEC (mg/kg-diet) for 2nd other bird species Body weight (g) of 2nd other avian species

Table 2. Mammalian Results

Parameter Acute Chronic Upper bound exposure (mg/kg-bw) 1.4792 1.4792 Adjusted toxicity value (mg/kg-bw) 1845.9854 0.6692 Ratio of exposure to toxicity 0.0008 2.2105

Conclusion* Drinking water exposure alone is NOT a potential

concern for mammals Exposure through drinking water alone is a potential

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic Upper bound exposure (mg/kg-bw) 6.9660 6.9660 Adjusted toxicity value (mg/kg-bw) 28.8172 0.0000 Ratio of exposure to acute toxicity 0.2417 0.0000

Conclusion* Exposure through drinking water alone is a potential
concern for birds Due to insufficient data, risk cannot be precluded

*Conclusion is for drinking water exposure alon e. This does not combine all routes of exposure. Therefor e, when aggregated with other routes ( i.e ., diet, inhalation, dermal ), pesticide exposure through drinking wate r may contribute to a total exposure that has potential for effects to non-target animals.Page 48 of 49 

## Appendix E. Degradates Summary for Pirimiphos-Methyl

Table E-1. Pirimiphos-methyl de gradation products identified in environmental fate studies.

Degradate Identity Structure Max% of Applied and Days

Post Application Comments

Hydrolysis (MRID Nos. 42982401 and 43177601)

2(diethylamino)-4- hydroxy-6-methyl pyrimidine

( Non-OP degradate ) 87.25%, 30 days (pH5)

22.51%, 90 days (pH7)

29.97%, 60 days (pH9) pH5 study
terminated at 30 days.

pH7 study
terminated at 90 days.

pH9 study
terminated at 60 days.

O-2 diethylamino-6-methylpyrimidin-4-yl omethyl-phosphorothioate

( OP Demethylated degradate ) 4.99%, 21 days (pH5)

26.54%, 90 days (pH7)

18.17%, 60 days (pH9) pH5 study
terminated at 30 days.

pH7 study
terminated at 90 days.

pH9 study
terminated at 60 days.

Aerobic Soil Metabolis m (MRID No. 135358)

2(diethylamino)-4- hydroxy-6-methyl pyrimidine

( Non-OP degradate ) 42.08%,,

Peartree Sandy Loam (SL1) at 70 days

55.58%,,
Frensham Sandy Loam (SL2) at 14 days

37.22%,,

Gore Loam (L) at 14 days

66.28 %,, Blackborough Peat (P) at 210 days Studies in all soils
terminated at 210 days. N N CH 3

N

C H 2 C H 2 C H 3 CH 3 O H

N N CH 3

N

C H 2 C H 2 C H 3 CH 3 O HPage 49 of 49 Table E-1. Pirimiphos-methyl de gradation products identified in environmental fate studies.

Degradate Identity Structure Max% of Applied and Days

Post Application Comments

Anaerobic Soil Metabolism (MRID No. 135358)

2(diethylamino)-4- hydroxy-6-methyl pyrimidine

( Non-OP degradate ) 61.4%,,

Peartree Sandy Loam (SL1) at 14 days

37.22%,,

Gore Loam (L) at 14 days Studies in all soils
terminated at 210 days.

Findings from
flooded water soil atmosphere reported. N N CH 3

N

C H 2 C H 2 C H 3 CH 3 O H