Page 2 of 107



### Table of Contents

Ex ecutive Summary

................................ ................................ ................................ ................................ ...... 4

1.0 Occupational and Residential Exposure/ Risk Assessment

................................ ............................ 11

1.1 Criteria for Conducting Exposure Assessments

................................ ................................ .......... 11

1.2 Toxicological Endpoints

................................ ................................ ................................ ............. 11

1.3 Incident Report

................................ ................................ ................................ ............................ 16

1.4 Use Profile

................................ ................................ ................................ ................................ .. 19

2.0 Occupational Exposures and Risks

................................ ................................ ................................ . 23

2.1 Occupational Handler Exposures and Risks

................................ ................................ ............... 23

2.1.1 Assumptions for Handler Exposure Scenarios

................................ ................................ .... 25

2.1.2 Exposure Data for Handler Exposure Scenarios

................................ ................................ . 28

2.1.3 Occupatio nal Handler Exposure Scenarios

................................ ................................ ......... 35

2.1.4 Occupational Handler Exposure and Risk Calculations

................................ ..................... 36

2.1.5 Occupational Handler and Exposure Risk Summary

................................ .......................... 38

2.1.6 Summary of Occupational Handler Exposure Data Gaps

................................ ................... 38

2.1.7 Occupational Handler Characterization

................................ ................................ .............. 40

2.2 Occupational Handler Comparison Using Biomonitoring Data

................................ ................. 42

2.2.1 Occupational Handler Biomonitoring Exposure and Risk Calculations

............................. 44

2.2.2 Occupational Handler Chemical Specific Data

................................ ................................ ... 45

2.2.2 Occupational Handler Comparison Using Biomonitoring Data Risk Summary

................. 51

2.3 Commercial Seed Treatment

................................ ................................ ................................ ....... 51

2.3.1 Assumptions for Commercial Seed Treatment Exposure Scenarios

................................ ... 52

2.3.2 Commercial Seed Treatment Exposure and Risk Calculations

................................ ........... 53

2.3.3 Commercial Seed Treatment and Exposure Risk Summary

................................ ............... 54

2.3.4 Commercial Seed Treatment and Exposure Risk Characterization

................................ .... 54

2.4 Occupational Post

- application Exposures and Risks

................................ ................................ .. 54

2.4.1 Occupational Post

- application Exposure Scenarios

................................ ............................ 54

2.4.2 Data/Assumptions for Post

- application Exposure Scenarios

................................ .............. 57

2.4.2.1 Post

- application Exposure Study Summaries

................................ ................................ .. 59

2.4.3 Use of Post

- application DFR Data

................................ ................................ ..................... 67

2.4.4 Occupational Post

- application Exposure and Risk Summary

................................ .................... 69

2.4.5 Summary of Exposure Data Gaps

................................ ................................ ....................... 76Page 3 of 107

2.4.6 Occupational Post

- application Characterization

................................ ................................ ...... 77

3.0 Residential Exposures and Risks

................................ ................................ ................................ .... 78

3.1 Residential Handler Exposures and Risks

................................ ................................ .................. 79

3.2 Residential Post

- application Exposures and Risks

................................ ................................ ..... 79

3.2.1 Data and Assumptions for Residential Handler Exposure Scenarios

................................ . 79

3.2.3 Residential Post

- application Risk Summary

................................ ................................ ....... 90

3.2.4 Residential Post

- application Exposure and Risk Characterization

................................ ..... 91

3.3 Resid ential Bystander Exposure and Risk

................................ ................................ .................. 92

3.3.1 Residential Bystander Exposure and Risk

................................ ................................ .......... 96

3.3.2 Residential Bystander Exposure and Risk C haracterization

................................ ............... 97

3.4 Spray Drift

................................ ................................ ................................ ................................ .. 98

4.0 Evaluation of Chlorpyrifos Oxon

................................ ................................ ................................ .... 99

4.1 Oxon Study Summaries

................................ ................................ ................................ ............ 100

4.2 Interpretation and Application of Oxon Studies

................................ ................................ ....... 106Page 4 of 107

Executive Summary

Chlorpyrifos (0,0

- diethyl

- 0

- 3 ,5,6

- trichloro

- 2

- pyridyl phosphorothioate) is a broad

- spectrum, organophosphate insecticide that was first registered in 1965 to control foliage

- and soil

- borne insect pests on a variety of food and feed crops. Chlorpyrifos is formulated as granular,

micr oencapsulated, soluble concentrate/liquids, water dispersible granular in water soluble packets (WSP) and wettable powder packaged in WSP, as well as impregnated paints, cattle ear tags and insect bait stations. A wide variety of application techniques ha ve been identified that could potentially be used to apply chlorpyrifos for agricultural use, such as tractor

- drawn equipment, open and closed mixing/loading, and hand held equipment. Applications of chlorpyrifos also include soil incorporated/directed us es, bark, root dip, foliar, seed treatments,

aerial and ground

- based fogger mosquitocide and golf course turf.

The purpose of this memorandum is to update the most recent comprehensive occupational and residential exposure/risk assessment of chlorpyrifos conducted in June 2000 (T. Leighton, D63893), “ Agricultural and Occupational Exposure Assessment and Recommendations for the Reregistration Eligibility Decision Document for Chlorpyrifos.” The update includes a

deterministic assessment of human health ex posure/risk to chlorpyrifos from agricultural handling of the pesticide and subsequent activity in treated areas, exposures in a residential environment after occupational application, as well as bystander exposure/risk from field

volatilization based on a vailable monitoring data.

A residential risk assessment for registered homeowner uses was performed in June 2000 (D. Smegal, D266562), “ Occupational/Residential Handler and Postapplication Residential/Non

Occupational Risk Assessment for Chlorpyrifos .” The findings of this analysis resulted in

voluntar y cancellation of a ll chlorpyrifos homeowner uses, except ant and roach baits in child

resistant packaging. A phase out was also developed for termite treatment products (post

- and

pre

- construction). Eve n though homeowner uses have been cancelled, uses remain for aerial and ground

- based fogger adult mosquitocide and for golf course turf applications which could result in exposures to the general population. An assessment of these uses for potential resid ential

post

- application exposure is included in this memorandum.

Exposure Data

A number of studies were considered in the development of the chlorpyrifos risk assessment that

includes scenario

- and/or chemical

- specific handler exposure data for occupat ional uses. The studies consist of biological monitoring and passive dosimetry exposure data, as well as dislodgeable foliar residue (DFR) data. Chemical

- specific occupational handler studies used for risk quantitation and/or characterization include: e xposure data for alfalfa, Christmas trees, corn, citrus, cotton, ornamentals, and wheat

. In all other cases, occupational handler exposure was addressed using PHED (Pesticide Handlers Exposure Database), the Outdoor Residential Exposure Task Force (ORETF) , and recently completed exposure scenario monographs as conducted and submitted by the Agricultural Handlers Exposure Task Force (AHETF). Occupational post

- application exposure/risk was addressed through the use of 7 DFR studies.

The DFR studies include : emulsifiable concentrate formulations on sugarbeets, pecans, citrus, sweet corn, cotton, and turf; wettable powder formulations on almonds, apples, pecans,Page 5 of 107

cauliflower, tomato and turf; granular formulations on sweet corn and t urf; a total release

aeros ol fo rmulation on ornamentals; and a microencapsulated formulation on ornamentals.

Review of Human Research

This risk assessment relies in part on data from studies in which adult human subjects were intentionally exposed to a pesticide or other chemical . These studies, which comprise AHETF, ORETF and PHED, as well as the majority of chemical

- specific handler exposure data were determined to require a review of their ethical conduct, have received that review, and have been

determined to be ethical. A s ingle handler exposure study, “Evaluation of Chlorpyrifos Exposure to Workers During Loading and Application of Lorsban® 15 % Granular Insecticide During Corn Planting ( MRID

- 444835 01),” was determined to have been conducted in a manner which prohibits it s use by the Agency.

Hazard Characterization

The toxicity database is considered substantially adequate to support chlorpyrifos human health

risk assessments. Chlorpyrifos, like other OPs, binds to and phosphorylates the enzyme, acetlycholinesterase ( A ChE ) , in both the central (brain) and peripheral nervous systems leading to accumulation of acetylcholine and, ultimately, to clinical signs of toxicity. In 2000, the Agency concluded for chlorpyrifos that i nhibition of cholinesterase ( ChE ) was the most s ensitive effect in all of the animal species evaluated (rats, mice, rabbits dogs) and in humans, regardless of exposure duration. The Agency is maintaining at this time, based on available data, that cholinesterase inhibition (ChEI) provides the most sens itive dose

- response information for deriving points of departure for chlorpyrifos.

Acute toxicity categories for the technical grade are Toxicity Category II for oral, dermal, and inhalation. It is a Toxicity Category III for primary eye and dermal irrit ation. The endpoints used in this document to assess chlorpyrifos exposure/risk include short

- and intermediate

- term endpoints. Long

- term (greater than 6 months) exposure durations are not anticipated based upon the use pattern of chlorpyrifos.

A rout e specific short

- and intermediate

- term dermal NOAEL of 5 mg/kg/day from a 21

- day dermal rat study (MRID 40972801) has been identified, and therefore, a dermal absorption adjustment is not necessary. The dermal LOAEL in this study of 10 mg/kg/day is based on plasma and red blood cell (RBC) cholinesterase inhibition (ChE) of 45 and 16 percent, respectively. Evaluation of biomonitoring data was conducted based on a comparison of the absorbed dose as measured by urinary excretion of 3,5,6

- trichloro

- 2

- pyridin ol (TCP), to the oral equivalent NOAEL of 0.15 mg/kg/day (i.e., 5 mg/kg/day from 21

- day dermal study x 0.03 dermal absorption) because the majority of exposure is via the dermal route. The dermal absorption factor of 3% was estimated based on the ratio of the oral LOAEL of 0.3 mg/kg/day from the rat developmental neurotoxicity study (MRIDs 44556901, 44661001) to the dermal LOAEL of 10 mg/kg/day from the 21

- day rat dermal study for plasma and red blood cell cholinesterase inhibition. This absorption factor is comparable to the dermal absorption (minimum 1

- 3%) estimated from human data in Nolan et al . (1982, MRID 00249203) by back

-Page 6 of 107

calculating chlorpyrifos exposure based on urinary levels of TCP. Most of the absorbed dose in the worker biomonitoring study is the result of dermal exposure.

Short

- and intermediate

- term inhalation risk assessments were based on two subchronic inhalation toxicity studies (MRID Nos.40013901, 40166501, 40908401) in the rat. Using the Agency‟s Reference concentration (RfC) method ology, a human equivalent concentration (HEC) was calculated and used to assess both occupational and residential exposure/risks. The short

and intermediate

- term inhalation HEC, 0.0057 mg/m 3 , calculated for residential exposures was

converted to a NOAEL of 0.56 mg/kg/day to allow for comparison to estimated occupational inhalation doses. The HECs are based on no effects on plasma or RBC ChE inhibition identified from the two rat inhalation studies. For residential bystander exposure, the HEC for acute

r esidential bystander exposure is 0.62 mg/m 3 and 0.0057 mg/m 3 for short

- and intermediate

- term exposure. Because the 90

- day study was conducted 5 days per week at 6 hours/day, the short

and intermediate

- term residential HEC was adjusted to represent conti nual, 24 hour/ 7 day exposure. In contrast, the occupational inhalation exposure was only adjusted to account for an 8 hour workday because worker exposure is expected to occur during the course of an average workweek (8 hours/day and 5 days/week).

For short

- term incidental oral exposure scenario, the results of the 11 day repeat phase of the new oral CCA study (MRID 48139301) indicated inhibition of RBC ChE in male PND11 rats as the most sensitive endpoint. A BMDL 10 of 0.1 mg/kg/day was derived from a BMD analysi s of

the dose

- response data. For intermediate

- term incidental oral exposure scenarios a BMDL 10 of 0.03 mg/kg/day was selected from pregnant (GD6

- 20) rats exposed to chlorpyrifos in the developmental neurotoxicity study (MRID 44556901, Hoberman et al . 1998a,b) on the basis of inhibition of RBC ChE in pregnant dams. This point of departure ( PoD ) was supported by a WOE evaluation of other studies including an oral gavage study in pregnant (GD6

- LD10) rats (MRID 44648101) and the new CCA study

.

A 1x FQPA safety factor (SF) is being proposed for this preliminary assessment for acute and chronic oral exposure along with all dermal durations and repeated inhalation exposures since the PoDs are selected from sensitive endpoints (RBC AChE inhibition) i n sensitive lifestages/sexes

. For acute inhalation exposure (PoD ) based on acute inhalation ChE study using adult rats), a 10X FQPA database uncertainty factor (UF) is applied to account for LOAEL to NOAEL extrapolation (a NOAEL was not identified in the study).

A total uncertainty factor of 100X was applied to endpoints selected for the short

- and

intermediate

- term incidental oral and dermal exposure s [ 10 X for interspecies extr apolation, 10X for intraspecies variation and a 1X FQPA factor (residential )].

For acute inhalation exposures, a total uncertainty factor of 300 X was applied [3 X for interspecies extr apolation (reduced from 10X because RfC methodology used), 10X for intraspecies variation and a 10X database uncertainty factor for extrapolation f rom a LOAEL to a NOAEL, and a 1X FQPA].Page 7 of 107

For short

- term and intermediate

- term inhalation exposures, a total uncertainty factor of 30 X was applied [3 X for interspecies extr apolation (reduced from 10X because RfC methodology used), 10X for intraspecies vari ation and a 1X FQPA].

Because the same adverse effect (i.e., ChE I) was seen following dermal, incidental oral and inhalation exposures, MOEs estimated for these routes of exposure can be combined. However,

because the LOCs for dermal/incidental oral and inhalation routes of expo sure are not the same (an MOE of 100 defines dermal/incidental oral while inhalation is defined by an MOE of

30 /300 ) an aggregate risk index (ARI) was required to combine or aggregate estimated MOEs.

EPA identifies as a level of c oncern ARIs that fail to reach or exceed the level of 1. Lower ARIs

raise a risk of concern.

Occupational Handler Exposure and Risk

Short

- (1 to 30 days) and intermediate

- term (1 to 6 months) exposure and risks were calculated for occupational handler s of chlorpyrifos for a variety of exposure scenarios at differing levels of personal protection. HED used 3 major unit exposure data sources, AHETF, ORETF and PHED,

as well as 2 non

- chemical specific handler exposure studies, to assess occupational handl er

exposure.

Of the 305 exposure scenarios assessed, 134 were not of concern at some level of personal protection (i.e., an ARI > 1). Ninety

- one (91) exposure scenarios were not of concern when engineering controls were considered. The remaining 80 sc enarios resulted in risks of concern to HED (i.e., an ARI < 1) at all levels of personal protection and engineering controls considered.

Occupational Handler Comparison Using Biomonitoring Data

In an effort to characterize occupational handler risk esti mates calculated using surrogate, passive dosimetry exposure data, HED has presente d a comparative analysis of these data and biomonitoring data available for applicable exposure scenarios. 5 chemical specific handler exposure studies submitted in the pas t in support of chlorpyrifos re

- registration were reviewed and considered for use. Ethical conduct was considered as a part of this review and all but one

were determined to be ethical relevant to the standards of the time that the studies were

conducted. Comparative risk estimates were calculated using absorbed doses measured from the

4 studies determined to be acceptable for quantitative risk assessment purposes. T he comparison

of handler risk estimates was limited based on the level of clothing and pe rsonal protection worn by the participants when the biomonitoring studies were conducted.

Of the 4 exposure scenarios compared, 3 (mixing/loading liquids for airblast application, airblast applications, and groundboom applications) res ult in biomonitori ng estimates of greater risk potential than those estimated using surrogate data (i.e., the estimated MOEs are lower)

. The analysis of the exposure scenario, mixing/loading liquids for aerial appli cation, results in reduced risk potential (a 3.8X reductio n in MOE estimate). Because a number of issues were identified which limit the utility of the available biomonitoring data, HED has determined that these data

are best suited for characterization of the estimates calculated for representative exposure

sce narios using the surrogate data

.Page 8 of 107

Commercial Seed Treatment

Short

- and intermediate

- term exposure and risks were calculated f or occupational handlers performing seed treatment activities in commercial settings and for occupational secondary

handlers from p lanting chlorpyrifos

- treated seeds. No chemical

- specific handler exposure data were submitted in support of this use pattern.

The majority, 61 of 64, occupational handler seed treatment exposure scenarios assessed (combined dermal and inhalation) resul ted in risk estimates which were not of concern to HED (i.e., an ARI > 1) at some level of personal protection. The remaining 3 exposure scenarios resulted in an ARI < 1 at all level of personal protection considered and, therefore, are of concern

to HED

. All s eed planter (secondary handler) combined short

- and intermediate

- term dermal and inhalation exposure scenarios assessed resulted in an ARI > 1 at some level of personal protection and, therefore, are not of concern to HED.

Occupational P ost

- applica tion Exposure and Risk

HED has assessed short

- and intermediate term occupational post

- application dermal expos ure and risk for any crops where reentry into an area previously treated with chlorpyrifos is anticipated. The assessment was completed using 7 chemical

- specific registrant submitted DFR

studies. The studies, which encompass the use of five different formulations and twelve different crops, have been extrapolated to other groups based on the nature of the crop and application

method and used to calculate risks for post

- application workers

The MOEs estimated for liquid spray and granular formulation reentry are not of concern (i.e., an MOE ≥ 100) in the range of 0 to 4 days for lower to medium exposure activities and 0 to 8 days for high exposur e activities, with the gr eater majority falling between 0 to 4 days when all exposure activities are considered. HED also estimated the MOEs for reentry into microencapsulated and total release fogger formulation treated greenhouses. These estimates

rang e from 0 to > 35 days after treatment (the completion of the monitoring period) for all exposure activities considered.

A quantitative occupational post

- application inhalation exposure assessment was not performed for chlorpyrifos given that an inhalati on exposure assessment was performed for occupational/commercial handlers and handlers are expected to have greater exposures

.

Residential Handler Exposure and Risk

Based upon review of all chlorpyrifos registered uses, only the roach bait products can be applied by a homeowner in a residential setting; however, a quantitative exposure/risk assessment for application of the roach bait products was not conducted because HED expects handler exposure to be negligible. With roach bait stations the active i ngredient is contained within the bait station, therefore, limiting contact with the active ingredient in the product.Page 9 of 107

Reside ntial Post

- application Exposure and Risk

C hlorpyrifos can be used in areas f requented by the general population including an t mounds, golf courses

, and as an aerial and ground

- based (thermal aerosol and fog machine) ULV mosquitocide applied by a public agency made in the vicinity of residential areas. As a result,

individuals could be exposed by entering these areas if they ha ve been previously treated. Post

application homeowner exposure from residential ant mound treatment (applied by professional only) was not quantitatively assessed because contact with the mound is not anticipated.

Estimated short

- term adult and child dermal and child incidental oral exposure to turf following aerial and ground mosquito treatments are not concern to HED (i.e., an MOE ≥ 100). Combined child exposure estimates (dermal and incidental oral) to turf following aerial mosquito treatment

are o f concern to HED; however, combined estimates following ground treatment are not of concern. Acute adult and child inhalation exposure following aerial mosquito treatment is not of concern (i.e., an MOE > 30), but is of concern following ground treatment.

Adult dermal exposure from golfing is not concern to HED (i.e., an MOE > 100) using any TTR region

- specific data for the emulsifiable concentrate formulation at the 1.0 lb ai/A, or 0.25 application rates.

Residential Bystander Exposure and Risk

HED has assessed residential bystander exposure to chlorpyrifos based on the available chemical specific ambient and application site air monitoring data. The chlorpyrifos bystander volatilization inhalation exposure assessment includes acute and short

- /inte rmediate

- term exposure scenarios. The acute scenario compares the maximum air concentration detected in the monitoring studies to the acute HEC. The short

- /intermediate

- term scenario compares the arithmetic mean chlorpyrifos air concentration detected in the monitoring studies to the short

and intermediate

- term HEC.

Of the 24 acute ambient air concentrations assessed, 4 result in a risk of concern to HED (i.e., an MOE < 300). No short

- /intermediate

- term ambient data assessed result in a risk of conce rn. Of the 5 acute application site air concentrations assessed, 3 resulted in a risk of concern. Of the 5

short

- and intermediate

- term application site air concentrations assessed, 4 resulted in risks of concern (i.e., an MOE < 30).

Spray Drift

Spra y drift is a potential source of exposure to residents nearby to spraying operations. This is particularly the case with aerial application, but, to a lesser extent, could also be a potential source of exposure from the ground application method employed for chlorpyrifos . The Agency has been working with the Spray Drift Task Force, EPA Regional Offices and State Lead Agencies for pesticide regulation and other parties to develop the best spray drift management practices (see the Agency‟s Spray Drift websi te for more information at http://www.epa.gov/opp00001/factsheets/spraydrift.htm). On a chemical by chemical basis, the Agency evaluates the need for interim mitigation measures for aerial applications for placementPage 10 of 107

on labels/labeling. The Agency has com pleted its evaluation of the new database submitted by the Spray Drift Task Force, a membership of U.S. pesticide registrants, and is developing a policy on how to appropriately apply the data and the AgDRIFT computer model to its risk assessments for pest icides applied by air, orchard airblast and ground hydraulic methods. After the policy is in place, the Agency may seek further refinements in spray drift management practices to reduce off

- target drift with specific products with significant risks associ ated with

drift.

A quantitative residential post

- application (acute) inhalation exposure (spray drift) assessment was conducted for ground and aerial ULV mosquitocide applied by a public agency made in the vicinity of residential areas

. HED used AgDRIFT (V 2.01), which is the model that was developed as a result of the efforts of the Spray Drift Task Force (SDTF) , to determine residue deposition and the airborne concentration of chlorpyrifos anticipated from aerial product application. Based upon this as sessment, it was determined that adult and child acute inhalation exposures following aerial mosquito treatments are not of concern to HED (i.e., an MOE > 300). Inhalation exposure from ground based ULV treatment was assessed by assuming that the entire

a ctive ingredient applied to a 1 acre area is airborne and available to be inhaled by a child or adult. The assessment of adult and child acute inhalation from ground mosquito treatment

resulted in a risk estimate of concern to HED.

Chlorpyrifos Oxon

HE D has considered the exposure potential for occupational and residential exposure to chlorpyrifos oxon. Workers reenter ing an environment previously treated with chlorpyrifos (occupational post

- application) and the general population residing near chlorpy rifos application sites (bystanders) could potentially be exposed to the oxon as chlorpyrifos is degraded in the

environment . Dermal exposure to the oxon could occur through contact with chlorpyrifos treated surfaces and inhalation exposure through airbo rne oxon. However, the likelihood of exposure to the oxon is slight due to its rapid deactivation to TCP. In an effort to further explore the potential for oxon exposure, HED has researched and reviewed all available information sources. Based upon this review, HED is requiring additional studies to address uncertainties regarding the formation of chlorpyrifos oxon in the air post

- application and its formation and decay in greenhouses.

Summary of Data Gaps

HED has considered all data sources availa ble for the assessment of occupational and residential exposure and risk. It has been determined that no new data are required are required for chlorpyrifos; however, data gaps were identified for the evaluation of chlorpyrifos oxon. As

summarized in the previous paragraph, HED intends to require additional studies to address uncertainties regarding the formation of chlorpyrifos oxon in the air post

- application and its formation and decay in greenhouses. Several data gaps were identified in the Registrat ion Eligibility Decision (RED) for the occupational and residential assessment of chlorpyrifos ( finalized 7/31/06 ; IRED issued 2/2002)

. All but one of these have been satisfied, confirmation of the area treated for sod farm chlorpyrifos treatment.Page 11 of 107

1.0 O ccupational and Residential Exposure/ Risk Assessment

This document serves to update the June 2000 occupational and residential exposure and risk assessment for the insecticide chlorpyrifos. It presents the results of the Health Effects Division‟s (HED) review of the potential human health effects of occupational and residential exposure to the chemical.

1.1 Criteria for Conducting Exposure Assessments

An occupational and/ or residential exposure assessment is required for an active ingredient if (1)

ce rtain toxicological criteria are triggered and (2) there is a potential for exposure to handlers during use or to persons entering treated sites after application is complete. Chlorpyrifos meets both criteria. There is potential for exposure to handlers from occupational applications and from subsequent activity in treated agricultural and residential areas

. Therefore, a risk assessment is required for occupational handlers, as well as for occupational and residential post

application exposures that can occur as a result of chlorpyrifos use.

1.2 Toxicological Endpoints

Table 1 .2 summarizes the chlorpyrifos toxicity endpoints and PoDs selected from a re

- evaluation of the database (including data submitted since the 2002 IRED/2006 RED). Based on the resu lts of benchmark dose (BMD) analyses and weight of the evidence (WOE) consideration of all quality and reliable data, the most sensitive compartment from the most sensitive sex in both juvenile and adult rats were identified and used for endpoint selection and PoD determination for the following exposure scenarios. The description of the primary toxicity studies used for selecting toxicity endpoints and points of departure for various exposure scenarios are presented

in A ppendix A of the Chlorpyrifos: Preli minary Human Health Risk Assessment for Registration

Review (6/27 /2011, D 388070 ).

Consistent with risk assessment on other OP and NMCs compounds, the Agency has used a benchmark response (BMR) level of 10% and has thus calculated BMD 10 s and BMDL 10 s. Th e
BMD 10 is the estimated dose where ChE is inhibited by 10% compared to background. The

BMDL 10 is the lower confidence bound on the BMD 10 . Extensive analyses conducted as part of the OP cumulative risk assessment (USEPA 2002) have demonstrated that 10% i s a level that can be reliably measured in the majority of rat toxicity studies, and is generally at or near the limit of sensitivity for discerning a statistically significant decrease in ChE activity across the brain compartment and is a response level c lose to the background brain ChE level. The Agency uses the BMDL, not the BMD, for use as the PoD since the BMDL accounts for variability of the

data.

The Agency has not performed BMD analysis on studies evaluating the effect of chlorpyrifos on

the devel oping brain as these do not provide dose response data amenable to BMD modeling analysis. Specifically, these studies, in general, may include only a single dose at a particular age, do not report graded responses (i.e., all or nothing effect), and/or sho w non

- monotonic dose response curves (e.g., response goes up then down). For these studies, the Agency simply

considered the doses used.Page 12 of 107

Toxicological endpoints were selected for the assessment of short

- and intermediate

- term

exposures

. Long

- term expo sure durations are not anticipated based upon the use pattern of chlorpyrifos. Risk assessments are required for occupational handlers and occupational and residential post

- application exposures that can occur as a result of chlorpyrifos use.

Incidental Oral

For short

- term incidental oral exposure scenario, the results of the 11 day repeat phase of the new oral CCA study (MRID 48139301) indicated inhibition of RBC ChE in male PND11 rats as the most sensitive endpoint. A BMDL 10 of 0.1 mg/kg/day was deriv ed from a BMD analysis of

the dose

- response data. For intermediate

- term incidental oral exposure scenarios a BMDL 10 of 0.03 mg/kg/day was selected from pregnant (GD6

- 20) rats exposed to chlorpyrifos in the developmental neurotoxicity study (MRID 4455690 1, Hoberman et al . 1998a,b) on the basis of inhibition of RBC ChE in pregnant dams. This PoD was supported by a WOE evaluation of other studies including an oral gavage study in pregnant (GD6

- LD10) rats (MRID 44648101) and the new CCA study.

A total unc ertainty factor of 100 X is appropriate for incidental oral exposures [ 10X for interspecies extrapolation, 10X for intraspecies variation and a 1 X FQPA factor].

Dermal

A short

- /intermediate

- term dermal PoD was selected from a 21

- day dermal toxicity study (MRID 40972801) in rats based on plasma and red blood cell ChE inhibition (NOAEL = 5 mg/kg/day).

The use of the 21

- day dermal toxicity study is appropriate for durations up to 6 months as it is expected that steady state ChE inhibition would have been rea ched by approximately 21 days of dermal exposure. The Agency has previously shown (USEPA, 2001; preliminary organophosphate cumulative risk assessment) that at or near 3

- 4 weeks of exposure the degree of inhibition following repeated dosing with OPs does not change with increasing duration but instead remains approximately the same.

For comparison to biomonitoring data in the risk assessment, which evaluates total exposure from oral, dermal and inhalation routes (in terms of absorbed dose), the 21

- day rat dermal study is used with an adjustment for 3% dermal absorption to convert the NOAEL of 5 mg/kg/day resulting from topically applied chlorpyrifos to an internal absorbed NOAEL = 0.15 mg/kg/day. The dermal absorption factor of 3% was estimated based o n the ratio of the oral LOAEL of 0.3 mg/kg/day from the rat developmental neurotoxicity study (MRIDs 44556901, 44661001) to the dermal LOAEL of 10 mg/kg/day from the 21

- day rat dermal study (MRID 40972801) for plasma

and red blood cell cholinesterase inhib ition. This absorption factor is comparable to the dermal absorption (minimum 1

- 3%) estimated from human data in Nolan et al . (1982, MRID 00249203) by back

- calculating chlorpyrifos exposure based on urinary levels of TCP. Most of the absorbed

dose in the worker biomonitoring study is the result of dermal exposure.

A total uncertainty factor of 100 X is appropriate for dermal exposures [ 10X for interspecies extrapolation, 10X for intraspecies variation and a 1X FQPA factor ].Page 13 of 107

Inhalation

An acute inhalation PoD was selected from a recently submitted special acute inhalation study (2010, MRID 48139303) based on lung and plasma ChE inhibition (LOAEL = 3.7 mg/m 3 ; NOAEL not established). In this special acute inhalation study, adult female rats (Crl:CD(SD))

were exposed nose only to atmospheric concentrations of 0, 3.7, 12.9, 22.1 or 53.5 mg/m 3 for six hours and allowed an additional 72 hours to recover. Using the Agency‟s Reference concentration (RfC) methodology, a human equivalent concentration (HEC) was calc ulated and used to assess acute bystander exposure and risks. The HEC for acute bystander exposure is 0.62 mg/m 3

.

Short

- and intermediate

- term inhalation risk assessments were based on two subchronic inhalation toxicity studies (MRID Nos.40013901, 4016650 1, 40908401) in the rat. Using the Agency‟s Reference concentration (RfC) methodology, a human equivalent concentration (HEC) was calculated and used to assess both occupational and residential exposure/risks. The short

and intermediate

- term inhalation HEC, 0.0057 mg/m 3 , calculated for residential exposures was converted to a NOAEL of 0.56 mg/kg/day to allow for comparison to estimated occupational inhalation doses. The HECs are based on no effects on plasma or RBC ChE inhibition identified

from the tw o rat inhalation studies. For residential bystander exposure, the HEC for acute residential bystander exposure is 0.62 mg/m 3 and 0.0057 mg/m 3 for short

- and intermediate

- term exposure. Because the 90

- day study was conducted 5 days per week at 6 hours/day , the short

and intermediate

- term residential HEC was adjusted to represent continual, 24 hour/ 7 day exposure. In contrast, the occupational inhalation exposure was only adjusted to account for an 8 hour workday because worker exposure is expected to occ ur during the course of an average workweek (8 hours/day and 5 days/week).

For acute inhalation exposures, a total uncertainty factor of 300X was applied [3 X for interspecies extrapolation (reduced from 10X because RfC methodology used which takes into consideration the pharmacokinetic differences between animals and humans ), 10X for intraspecies variation, and a 10X FQPA database uncertainty factor (for extrapolation from a

LOAEL to a NOAEL ).

For short

- term and intermediate

- term inhalation exposures, a total uncertainty factor of 30 X was applied [3 X for interspecies extr apolation (reduced from 10X because RfC methodology used), 10X for intraspecies variation and a 1X FQPA (because the inhalation NOAEL is considered protective of pregnant females base d on effects seen in the DNT at 0.3 mg/kg/day)].

Determination of Acute and Chronic Dietary PoDs for Chlorpyrifos Oxon

There is some potential for direct exposure to the oxon metabolite of chlorpyrifos, particularly from drinking water. BMD modeling of available oxon data for acute and repeated dosing studies was conducted (Appendix E, Tables 7 and 8). The purpose of this analysis is to determine the toxicological PoDs for the oxon (Table 4.8.2 ) and to assess the relative potency of chlorpyrifos and it s oxon metabolite.Page 14 of 107

A BMDL 10 of 0.05 mg/kg/day associated with RBC ChE inhibition in male rat pups exposed to chlorpyrifos oxon (acute dosing CCA study using oxon) was selected for the acute dietary PoD

for the oxon. An uncertainty factor of 100 X (10 X to a ccount for interspecies extrapolation and

10X for intraspecies variation) is applied to the BMDL 10 to obtain an aRfD of 0.0005 mg/kg/day. Based on the FQPA factor of 1, the acute population adjusted dose (aPAD) is 0.0005 mg/kg/day.

The chronic dietary P oD for chlorpyrifos oxon is selected from a BMDL 10 of 0.011 mg/kg/day from an 11 day repeat dosing CCA study using oxon and is based on inhibition of RBC ChE in

adult female rats. A comparison of the resulting BMD 10 s for juvenile and for adult rats indic ates that juvenile rats are no more sensitive to the oxon than are adult rats . The BMDL10 for adult rats (0.011 mg/kg/day) was selected for the PoD because it was lower than that of the juvenile rats (0.025 mg/kg/day) and would be considered protective for juveniles. Uncertainty factors of 10X to account for interspecies extrapolation and 10X for intraspecies variation is applied to the

BMDL 10 to obtain an aRfD of 0.00011 mg/kg/day. Based on the FQPA factor of 1, the chronic population adjusted dose (cPAD) is 0.000011 mg/kg/day.

While the Agency uses the BMDL, not the BMD, for use as the PoD since the BMDL accounts for variability of the data, the BMD 10 provides a point of comparison across studies and the

BMD 10 provides the basis for determining the relati ve toxicity of the chlorpyrifos oxon compared to chlorpyrifos. A toxicity factor for the oxon was calculated by dividing the chlorpyrifos BMD 10 for the endpoint associated with the most sensitive compartment from the

most sensitive sex for the duration of interest by the corresponding BMD 10 for the oxon. Acute (all populations) toxicity factors of 8.8 (males) and 11.9 (females) were calculated from BMD analysis of inhibition of male and female pup RBC ChE (acute phase of the CCA study). The

chronic toxici ty factor of 18.0 was derived from BMD analysis of inhibition of RBC ChE in adult female rats (adult male rats not examined) observed in the repeated phase of the CCA study. The toxicity factors may be used in aggregate assessments where exposures to

chlo rpyrifos and the oxon are to be combined. Adjusting for relative toxicity will allow comparison of the combined exposures to a single PoD (since PoDs are different for chlorpyrifos and oxon).

Table 1.2 Summary of Toxicity Endpoints Selected for Chlorpy rifos

Exposure

Scenario Dose

(mg/kg/day) Endpoint Study

Dermal

Short

- (1

– 30 days) and

Intermediate

- Term (1

- 6 months) NOAEL = 5

Absorbed dermal

NOAEL = 0.15 ( for assessment of biomonitoring data )

UF A = 10 x UF H = 10 x FQPA SF = 1 x (residential) Plasma and RBC ChE

inhibition 21

- day dermal study (NOAEL) and 4 day probe study (LOAEL) in adult rats (MRID 40972801)Page 15 of 107

Table 1.2 Summary of Toxicity Endpoints Selected for Chlorpy rifos

Exposure

Scenario Dose

(mg/kg/day) Endpoint Study

Oc cu pational and

residential LOC is an

MOE = 100

Acute Inhalation HEC = 0.62 mg/m3

(residential)

UF A = 3x

UF H = 10x

UF L = 10x FQPA SF = 1x (residential)

OR

UF A = 3x

UF H = 10x FQPA UF DB = 10x (LOAEL to NOAEL and lifestage sensitivity) (residential)

Residential LOC for

MOE=300 Lung ChE Inhibition Special 6 hour acute inhalation study (MRID 48139303)

Inhalation

Short

- (1

– 30 days) and

Intermediate

- Term (1

– 6 months) NOAEL (HEC) = 0. 56

mg/kg/day (occupational)

HEC = 0.0057 mg/m 3

(residential)

UF A = 3 x UF H = 10 x FQPA SF = 1 x (residential)

Occupational and

Residential LOC is an

MOE = 30 Lack of effects in 2 rat

inhalation studies at the highest dose tested : 43% plasma and 41% RBC ChE inhibition following oral doses of 0.3 mg/kg/day in the DNT study mg/kg/day in the DNT study Two 90

- day inhalation

studies and the rat DNT study (MRIDs 40908401; 40013901/ 40166501)

Incidental Oral

Sh ort

- Term (1

- 30 days) BMDL 10 = 0.1

UF A = 10 x UF H = 10 x FQPA SF = 1 x

Residential LOC is an Inhibition of RBC ChE in

PND 11 male rats 11 day repeat oral CCA study in the rat (MRID 48139301)Page 16 of 107

Table 1.2 Summary of Toxicity Endpoints Selected for Chlorpy rifos

Exposure

Scenario Dose

(mg/kg/day) Endpoint Study

MOE= 100

Incidental Oral

Intermediate

- Term (1

– 6 months) BMDL 1 0 = 0.03

UF A = 10 x UF H = 10 x FQPA SF = 1 x

Residential LOC is an

MOE= 100 Inhibition of RBC ChE in rat dams (GD 6

– 20). Weight of evidence from studies including:

Developmental
neurotoxicity study
in pregnant (GD 6

- 20) rats (MRID
44556901)

G avage study in pregnant (GD 6

– LD10) rats (MRID 44648101)
NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty

factor. UF A = extrapolation from animal to human (interspecies). UF H = potential variation in sensitivity among members of the human population (intraspecies). UF L = use of a LOAEL to extrapolate a NOAEL. UF DB = to account for the absence of key data (i.e., lack of a critical study) or other residual uncertainties as evidenced by

available data . FQPA SF = FQPA Safety Factor. MOE = margin of exposure. LOC = level of concern.

1.3 Incident Report

The incident review was conducted by HED considering different types and sources of human observational information (medical data/information, huma n incident data and epidemiological information) in an effort to consider different lines of evidence that may inform the re

- evaluation of chlorpyrifos in this phase of Registration Review. The symptoms reported in the medical

human observational data and human incident data reviewed for this report are mutually supportive. The symptoms reported for both types of observational data include cardiovascular, respiratory, gastrointestinal, nervous system and ocular symptoms. The Agency‟s risk mitigation

meas ures including canceling all homeowner use product registrations (except ant bait stations), and canceling uses in schools and parks where children may be exposed appears to have led to a decrease in the number of incidents reported in residential areas. The databases that were reviewed (OPP Incident Data System, National Pesticide Information Center, NIOSH

Sentinel Event Notification System for Occupational Risks [SENSOR], and California Pesticide Illness Surveillance Program Incident Data [CA PISP]) show ed the number of incidents associated with chlorpyrifos significantly declined post

- 2002 and this correlates well with the phase out/cancellation of the almost all chlorpyrifos residential products as of December 31,

2001. In addition, the Agency's findin gs are also consistent with other incident cases investigations of American Association of Poison Control Centers (AAPCC) data which have reported a decrease in the number of chlorpyrifos incidents that is temporally associated with the phase out/cancellat ion of most residential chlorpyrifos products. For AAPCC data, the mean annual number of reports for chlorpyrifos in the pre

- and post

- announcement phases was 214 andPage 17 of 107

39.3, respectively (Stone et al. 2009). In IDS, there were 43 incidents reported in 20 02 and only six reported in 2009.

However, chlorpyrifos occupational incidents, reported in CA PISP and SENSOR databases, appear to be constant over time, despite risk mitigation implemented including reduced application rates and seasonal maximum limits, increased retreatment intervals, increased PPE and/or use of engineering controls were required as well as increased reentry intervals (REIs) for a number of crops. In NIOSH SENSOR application of chlorpyrifos appears to lead to the most incidents, being responsible for 46% reported to NIOSH SENSOR from 1998 to 2007 and in CA PISP drift of chlorpyrifos from adjacent fields appears to be the cause of the most incidents, being responsible for 56% of the cases reported to CA PISP from 1999 to 2008.

For NIOS H SENSOR from 1998 to 2007, there are 635 cases reported for chlorpyrifos in the database. Of these cases, 348 were reviewed because, in these cases, chlorpyrifos was used as a single chemical only and had a certainty classification of definite, probable, or possible , as these cases provide more certain information about the potential effects of chlorpyrifos exposure

. There was one death due to suicide; eight cases were classified as high severity, 60 cases were classified as moderate severity, and 279 cas es were classified as low severity

. Of the 348 cases chlorpyrifos

- only cases, 18 cases involved children six years old or younger. These incidents were mostly due to accidental ingestions, misapplications around the home and drift from nearby properties. The health effects reported include: neurological, gastrointestinal

, respiratory , ocular

, dermal, cardiovascular , and genitourinary

.

Generally, chlorpyrifos incidents involved workers in agricultural or professional application occupations, homeowners and individuals at work but their job was not related to pesticide application, and to individuals exposed through drift.

On average, less than seven incidents are reported per year for chlorpyrifos in the NIOSH

SENSOR database. The number of incident s reported appears to remain steady from 1998 to 2007. Agricultural workers reported incidents that occurred due to drift from adjacent fields;

post

- application exposure, chlorpyrifos application, mixing/loading chlorpyrifos, repair and maintenance of equ ipment, chlorpyrifos transportation and disposal, and spills/splashes/leaks of chlorpyrifos onto workers (see Figure 4). Application of chlorpyrifos appears to lead to the most incidents, being responsible for 46% reported to NIOSH SENSOR from 1998 to 200 7.Page 18 of 107

Figure 1.3 a : Occupational exposure scenario s reported to NIOSH Sensor for c hlorpyrifos

One hundred and sixty four cases were identified that are attributable to chlorpyrifos

- only exposures were reported to the CA PISP between 1999 and 2008. Of th ese cases, 87 were occupational incidents and 77 were non

- occupational incidents. The health effects reported include: neurological, gastrointestinal, respiratory, ocular, dermal, cardiovascular.

On average less than nine agricultural incidents are repor ted per year for chlorpyrifos in the CA PISP database. The number of incidents reported appears to remain steady from 1999 to 2008. Agricultural workers reported incidents that occurred due chlorpyrifos drift from adjacent fields;

post

- application, spill /splash/leak, mixer/loader, and applicator exposure, misuse, equipment malfunction, and equipment cleaning (See Figure 6). Unlike in SENSOR, where application was the most likely activity involved in incidents, in PISP drift of chlorpyrifos appears to be the cause of the most incidents, being responsible for 56% of the cases reported to PISP from 1999

to 2008.Page 19 of 107

Figure 1.3b: Occupational exposure scenario s reported to CA PISP for c hlorpyrifos

In summary, chlorpyrifos incidents reported have declined sub stantially among residential users from 2002 to May 27, 2010, but the occupational incidents reported remain the same. The incidents reported have been reviewed and, overall, the numbers and severity of incidents associated with chlorpyrifos use are not o f significant potential public health concern, but we will continue to monitor these incidents and remain alert for any changes in trend or patterns.

1.4 Use Profile

Chlorpyrifos is an organophosphate insecticide currently registered for the control of v arious insects. Targeted pests include aphids, cockroaches, cutworms, fleas, grasshoppers, ticks, etc. Chlorpyrifos is manufactured as granular, microencapsulated, soluble concentrate/liquids, water dispersible granular in water soluble packets (WSP) and wettable powder packaged in WSP

formulations , as well as impregnated paints, cattle ear tags, insect bait stations and total release foggers. Registered use sites include the following uses: food crops, including fruit and nut trees, many types of fruits and vegetables, and grain crops; and non

- food crops such as forage, golf course turf, industrial sites, greenhouse and nursery production, sod farms, and wood products. Public health uses include aerial and ground

- based fogger treatments to control

mosqu itoes. There are a wide range of application rates. HED has conducted a review of all active product labels. Tables 1.4a and 1.4b below summarize all agricultural and non

agricultural use sites identified for chlorpyrifos under this review, respectively

. Maximum application rate (lb ai/A) and application equipment for each site are also identified. Various chlorpyrifos product formulations are represented by the application rates and methods.Page 20 of 107

Table 1

. 4a Summary of Maximum Application Rates for C hlorpyrifos Agricultural Uses

Crop or Target Maximum Application Rate (lb ai/A) Application Equipment

Alfalfa 1.0 Aerial, Chemigation, Groundboom, Tractor Drawn Spreader Asparagus 1.0 Aerial, Groundboom

1.5 Tractor Drawn Spreader

Beets (Table and Sugar Grown for Seed) 1.9 Aerial

Brassica Vegetable (Bok Choy, Broccoli, Broccoli Raab, Brussel Sprout, Cabbage, Cauliflower, Chinese Broccoli, Collards, Kale, and Kohlrabi) 1.0 Aerial

2.3 Groundboom, Tractor Drawn Spreader

Carrot (Grown for Seed) 0.9 4 Aerial, Groundboom

Citrus Fruit 6.0 (AZ and CA), 3.5 (States other than AZ and CA) Aerial, Airblast, Groundboom

1.0 Tractor Drawn Spreader

4.0 Backpack Sprayer, Handgun, Low

Pressure Handwand Clover (Grown for Seed) 1.0 Aerial, Groundboom Corn (Fi eld, Grown for Seed and Sweet) 1.5 Aerial, Chemigation

3.0 Groundboom

1.3 Tractor Drawn Spreader

Cotton 1.0 Aerial, Chemigation, Groundboom Cranberry 1.5 Aerial, Chemigation, Groundboom Fig (CA only) 2.0 Groundboom Grapes 2.0 Airblast

1.0 Backpac k Sprayer, Low Pressure

Handwand Legume Vegetables (Succulent or Dried, Except for Soybeans) 1.0 Groundboom

Mint (Peppermint and Spearmint) 2.0 Chemigation, Groundboom Onion (Dry Bulb) 1.0 Groundboom, Tractor Drawn Spreader, Handgun

Peanut 2.0 Aerial, Groundboom, Tractor Drawn Spreader Peppers 1.0 Groundboom Pineapple (Non

- bearing) 1.9 Groundboom, Airblast

Radish 2.8 Aerial, Groundboom, Tractor DrawnPage 21 of 107

Table 1

. 4a Summary of Maximum Application Rates for C hlorpyrifos Agricultural Uses

Crop or Target Maximum Application Rate (lb ai/A) Application Equipment

Speader, Handgun Radish (Grown for Seed) 0.94 Aerial, Groundboom Rutabaga 2.3 Aerial, Groundboom, Tractor Drawn Spreader Sorghum 1.0 Aerial, Chemigation, Groundboom

3.3 Tractor Drawn Spreader Soybean 1.0 Aerial, Chemigation, Groundboom Strawberry 1.0 Aerial

2.0 Groundboom Sugarbeet 1.0 Aerial, Chemigation, Groundboom

2.0 Tractor Drawn Spreade r Sugarbeet (Grown for Seed) 1.9 Aerial, Chemigation, Groundboom

Sunflower 2.0 Aerial, Groundboom

Sweet Potato 2.0 Groundboom, Tractor Drawn Spreader

Tobacco 2.0 Groundboom, Tractor Drawn Spreader Tree Nuts (Almonds, Filberts, Pecans, Walnuts) 4.0 Gro undboom, Handgun

2.0 Aerial, Airblast 0.03 (lb ai/gallon) Low Pressure Handwand, Backpack

Sprayer Tree Fruit (Apples, Cherry, Nectarine, Peach, Pear, Plum, Prune, Sour Cherry) 2.0 Aerial, Airblast

0.03 (lb ai/gallon) Backpack Sprayer, Drench/Dip,

Ha ndgun, Low Pressure Handwand

Turnip 2.3 Groundboom, Tractor Drawn Spreader

Wheat 1.0 Aerial, Chemigation, Groundboom

2.0 Groundboom

Table 1

. 4b Summary of Maximum Application Rates for Chlorpyrifos Non

- Agricultural

Uses

Crop or Target Maximum App lication Rate (lb ai/A) Application Equipment

Ants (Fire Ant Mound, Carpenter) 0.080 (lb ai/gallon) Backpack Sprayer, Handgun, Low

Pressure Handwand Cattle Ear Tags 0.0033 (lb ai/ ear tag) Hand

Christmas Trees (Nurseries and Plantations, Stumps) 1.0 Airblast

0.94 Aerial (Helicopter) 0.03 (lb ai/gallon) Backpack Sprayer, Handgun, Low

Pressure Handwand

Golf Course Turf 1.0 Belly Grinder, Low Pressure Handwand, Push Type Spreader,Page 22 of 107

Table 1

. 4b Summary of Maximum Application Rates for Chlorpyrifos Non

- Agricultural

Uses

Crop or Target Maximum App lication Rate (lb ai/A) Application Equipment

Tractor Drawn Spreader , Turfgun Grass Seed (Perennial Crops) 1.0 Groundboom Greenhouse and Nursery Production (Bedding Plants, Containerized Ornamentals, Cut Flowers, Flowering Hanging Baskets, Pine Seedling Transplant, Potted Flowers, Ornamentals, Trees and Shrubs) 4.0 Aerial, Groundboom

1.1 Belly Grinder, Push T ype Spreader,

Tractor Drawn Spreader

1.0 Airblast 0.16 (lb ai/gallon) Backpack Sprayer, Handgun, Low

Pressure Handwand 0.02 (lb ai/gallon) Soil Drench

0.01 (lb ai/can) Total Release Fogger

Mosquitocide (Outdoor Residential, Recreational, or Other Non

- Cropland Areas) 0.010 Wide Area Aerial and Ground

Non

- crop Areas (Commercial Indoor/Outdoor Industrial Sites, Commercial Livestock Holding and Housing, Dumpsters/ Trash Areas, Food Processing Plants, Grown for Seed, Industrial Plant Site Perimeter

T reatments, Manufacturing Sites, Power Utilities, Railroad Box Cars, Railroad Equipment, Road Medians, Ship Holds, Sod Farms, Telecommunications, Warehouse Sites) 1.0 Aerial, Belly Grinder, Groundboom, Push Type Spreader, Tractor Drawn Spreader

0.11 (lb ai/gallon) Backpack Sprayer

0.080 (lb ai/gallon) Handgun, Low Pressure Handwand,

Paint Brush/Roller 0.044 (lb ai/ 1,000 sq ft) Shaker Container

0.018 (lb ai/ 1,000 sq ft) Open Pour Bag

Ornamentals (Cut Flowers, Industrial Buildings/Plant Sites Perimet er Treatments and Road Medians, Evergreens, Field Grown Nursery Stock, Flowers, Greenhouses, Non

bearing Fruit Trees Shrubs, Nurseries, Trees, Vines, Woody) 6.0 Belly Grinder, Push Type Spreader, Tractor Drawn Spreader

4.0 Groundboom

2.0 Aerial, A irblast

0.16 (lb ai/gallon) Backpack Sprayer, Handgun, High

Pressure Handwand, Low Pressure

Handwand 0.020 (lb ai/gallon) Drench/Dip

Roach Control Bait Stations 0.00040 (lb ai/gallon) Hand

Sewer Manhole Walls 0.080 (lb ai/gallon) Backpack Sprayer, Lo w PressurePage 23 of 107

Table 1

. 4b Summary of Maximum Application Rates for Chlorpyrifos Non

- Agricultural

Uses

Crop or Target Maximum App lication Rate (lb ai/A) Application Equipment

Handwand, Paint Brush/Roller Total Release Fogger (Greenhouse Bedding Plants, Cut Flowers, Flowering Hanging Baskets, Potted Flowers, Ornamentals) 0.010 (lb ai/container) Hand

Trees (Cottonwood and Poplar Trees Grown for Pulp, Conifer, Deciduo us, Grown in Nurseries and Greenhouses) 2.0 Airblast, Handgun, Low Pressure Handwand, Backpack Sprayer

1.9 Aerial

Turfgrass (Sod or Seed) 4.0 Aerial, Groundboom

1.0 Tractor Drawn Spreader Wood Products (Fence Posts, Industrial Sites, Landscap e Timbers, Logs, Manufacturing, Pallets, Processed Wood, Right of Way, Railroad Ties, Utility Poles, Wooden Containers) 6.0 Belly Grinder, Push Type Spreader

0.17 (lb ai/gallon) Low Pressure Handwand

0.080 (lb ai/gallon) Backpack Sprayer, Handgun, Pa int

Brush/Roller

2.0 Occupational Exposures and Risks

It has been determined there is a potential for exposure in occupational scenarios from handling chlorpyrifos products during the application process (i.e., mixer/loaders, applicators, flaggers and

m ixer/loader/applicators , commercial seed treatment ) and from entering areas previously treated

with chlorpyrifos (e.g., post

- application work er exposure). As a result, risk assessments have been completed for the occupational handler and post

- application exposure scenarios.

This section includes the occupational aspects of the risk assessment. Occupational handler exposures and risks are addressed in the following Sections: 2.1: Occupational Handler Exposures and Risks, 2.2: Occupational Handler Comparis on Using Biomonitoring Data, and 2.3: Commercial Seed Treatment. Occupational post

- application exposures and risks are addressed in Section 2.4: Occupational Post

- application Exposure and Risks.

2. 1 Occupational Handler Exposures and Risks

HED uses th e term “handlers” to describe those individuals who are involved in the pesticide application process. HED believes that there are distinct tasks related to applications and that exposures can vary depending on the specifics of each task. Job requirements (e.g., the amount of chemical to be used in an application), the kinds of equipment used, and the target being treated can cause exposure levels to differ in a manner specific to each application event.Page 24 of 107

HED uses exposure scenarios to describe the various types of handler exposures that may occur for a specific active ingredient. The use of scenarios as a basis for exposure assessment is very

common as described in the U.S. EPA Guidelines for Exposure Assessment (U.S. EPA; Federal

Re gister Volume 57, Number 104; May 29, 1992). Information from the current labels, use and usage information, toxicology data, and exposure data were all key components in the development of the exposure scenarios.

HED has developed a series of general d escriptions for tasks that are associated with pesticide applications. Tasks associated with occupational pesticide handlers are categorized using one of the following terms:

Mixer/Loaders: these individuals perform tasks in preparation for an applicati on. For example, prior to application, mixer/loaders would mix the chlorpyrifos and load it into the holding tank of the airplane or groundboom equipment.

Applicators: these individuals operate application equipment during the release of a pesticide prod uct into the environment. Applications can be made using equipment such as airplanes or groundboom equipment.

Mixer/Loader/Applicators and/or Loader/Applicators: these individuals are involved in the entire pesticide application process (i.e., they do all job functions related to a pesticide application event). These individuals would transfer chlorpyrifos into the application equipment and then also apply it.

Flaggers: these individuals guide aerial applicators during the release of a pesticide produ ct onto an intended target.

HED risk assessors must understand how exposures to chlorpyrifos occur (i.e., frequency and duration) and how the patterns of these occurrences can cause the effects of the chemical to differ (referred to as dose response). Wh erever possible, use and usage data determine the appropriateness of certain types of risk assessments. Other parameters are also defined from use and usage data such as application rates and application frequency. HED always completes non

cancer risk as sessments using maximum application rates for each scenario because what is possible under the label (the legal means of controlling pesticide use) must be evaluated in order to ensure there are no concerns for each specific use.

A chemical can produce di fferent effects based on how long a person is exposed, how frequently exposures occur, and the level of exposure. It is likely that chlorpyrifos exposure can occur in a variety of patterns. The Agency believes that occupational chlorpyrifos exposure can occur over a single day or up to weeks at a time, even though each crop or application target is generally treated only a few times per season. Intermittent exposures over several weeks and months are also anticipated. Some applicators may apply chlorpyr ifos over a period of several weeks because to cover large acreages, they may be custom or professional applicators that are completing a number or applications within a region, or they may be applying chlorpyrifos over a period of several days. HED class ifies exposures up to 30 days as short

- term, exposuresPage 25 of 107

greater than 30 days up to 6 months as intermediate

- term and exposures greater than 6 months as long

- term.

Under current policy, both short

- and intermediate

- term assessments are completed for

occup ational scenarios in essentially all cases, because these kinds of exposures are likely and acceptable use/usage data are not available to justify disregarding intermediate

- term scenarios. This current policy differs from the policy in effect when earlier chlorpyrifos assessments were completed, in which HED assumed that agricultural handling of pesticides like chlorpyrifos involved only short

- term exposure. For chlorpyrifos, HED has completed both short

- term and

intermediate

- term assessments because of l ikely extended periods of exposure in segments of the user population and due to in the absence of crop

- and use

- specific information indicating

otherwise. Long

- term exposure (essentially every working day over a year) is not anticipated based upon the us e profile of chlorpyrifos. Dow AgroSciences submitted a draft survey plan to the Agency following discussions with HED about the potential usefulness of additional information regarding the exposure durations for occupational handlers of chlorpyrifos. HE D reviewed the draft survey plan in a 12/2/2009 memorandum (W. Britton, D 368391) and was of the view that “the survey may help clarify the nature of the user population who may be exposed

over an intermediate

- term allowing for a more informed risk manageme nt decision; however, it is unlikely to alter the Agency‟s intention to assess intermediate

- term risks in future occupational assessments for chlorpyrifos, consistent with current policy. ” HED suggested revisions to improve the survey‟s potential utility for risk characterization purposes. The review was based upon input from the HED, the Biological Economic Analysis Division, and OPP‟s human subjects research ethics staff. HED has received no further correspondence regarding the draft survey plan since the time of the memorandum.

Occupational handler exposure assessments are completed by HED using different levels of risk mitigation. Typically, HED uses a tiered approach. The lowest tier is designated as the baseline exposure scenario (i.e., long

- s leeve shirt, long pants, shoes, socks, and no respirator). If risks are of concern at baseline attire, then increasing levels of personal protective equipment or PPE (e.g., gloves, double

- layer body protection, and respirators) are evaluated. If risks re main a concern with maximum PPE, then engineering controls (e.g., enclosed cabs or cockpits, water

- soluble packaging, and closed mixing/loading systems) are evaluated. This approach is used to ensure that the lowest level of risk mitigation that provides adequate protection is selected, since the addition of PPE and engineering controls involves an additional expense to the user and

– in the

case of PPE

– also involves an additional burden to the user due to decreased comfort and dexterity and increased he at stress and respiratory stress.

2.1.1 Assumptions for Handler Exposure Scenarios

A series of assumptions and exposure factors served as the basis for completing the occupational

handler risk assessments. Each assumption and factor is detailed below on an individual basis. The assumptions and factors used in the risk calculations include:

Occupational handler exposure estimates were based on surrogate data from: (1) the

Pesticide Handle rs Exposure Database (PHED), (2) the Outdoor Residential Exposure Task Force (ORETF), and proprietary data. Data from the Agricultural HandlersPage 26 of 107

Exposure Task Force (AHETF) were used; however, at the time of this assessment, only a few exposure scenarios h ad been reviewed and approved for use by HED. The AHETF

scenarios were recently posted and are publically available on the EPA website as of

4/8/2011 ( http://www.epa.gov/pesti cides/science/handler

- exposure

- data.html ). This new data were included in the presentation of the most current data used to assess exposure and risk for occupational pesticide handlers.

HED assumes the maximum application rates allowed by labels in its risk assessments.

The adverse effects for the short

- and intermediate

- term dermal and inhalation endpoints are based on studies where the effects were observed in males and females, therefore the average body weight of an adult handler (i.e., 70 kg) is u sed to complete the risk

assessment.

Risk estimates for dermal and inhalation exposure were combined for chlorpyrifos because common toxicity endpoints (i.e., p lasma and RBC ChE inhibition) were used to

calculate risks.

The LOC for short

- and interme diate

- term occupational dermal exposure ( defined as an MOE = 1 00) differs from t he LOC for short

- and intermediate

- term occupational

inhalation exposure ( defined as an MOE = 3 0). A n aggregate risk index (ARI) is required to combine or aggregate risk from differing routes of exposure when the LOCs

are not the same. EPA identifies as a level of concern ARIs that fail to reach or exceed

the level of 1. Lower ARIs raise a risk of concern

.

Short

- and inter mediate

- term occupational risk assessments were c ompleted based on the toxicity endpoints identified. The same toxicological endpoint was selected for short

and intermediate

- term dermal chlorpyrifos exposures; therefore risk results for all dermal durations are identical. The same applies to all short

- and intermediate

- term inhalation

e xposure risk estimates. Long

- term exposure durations are not anticipated based upon the use pattern of chlorpyrifos.

An absorption rate was not used for short

- and intermediate

- term dermal risk assessment

because the dermal toxicological endpoint selected for both durations is derived from a

21

- day dermal study.

Generic protection factors (PFs) were used to calculate exposures when data were not available. For example, a filtering face piece dust mask is assumed to have a PF of 5 (i.e. reduces inhalation exposure by 80%). A half face elastomeric respirator with appropriate cartridges is assumed to have a PF of 10 (i.e. reduces inhalation exposure by 90%).

The average occupational workday is assumed to be 8 ho urs.

HED assumes that 1% of the maximum application rate of each cattle ear tag and roach bait station applied transfer to the handler.Page 27 of 107

The daily areas treated were defined for each handler scenario (in appropriate units) by determining the amount tha t can be reasonably treated in a single day (e.g., acres, square feet, or gallons per day). When possible, the assumptions for daily areas treated are taken from the Health Effects Division Science Advisory Committee on Exposure SOP #9: Standard Values for Daily Acres Treated in Agriculture, which was completed on July 5, 2000. However, standard values are not available for numerous scenarios. Assumptions for these scenarios are based on

HED estimates a nd could be further refined by input from affected se ctors. The following daily volumes handled and acres, excerpted from the policy, to be treated in each occupational

scenario include:

Aerial: 1

, 200 acres for large field crops, 350 acres for other field crops, and 7

, 500 acres for mosquito control adulti cide applications;

Groundboom: 200 acres for large field crops (e.g., corn and wheat), 80 acres treated for other field crop groundboom applications, and 40 acres on golf course turf;

Airblast: 40 acres for treated agricultural applications;

Flaggers: 350 acres for all crops;

Ground Fogger (Truck Mounted): 3

, 000 acres for mosquito control;

High Pressure Handwand and Handgun: 1,000 gallons of spray solution prepared when mixing/loading liquids for application or making the application, or application to 5

acres;

Backpack Sprayer or Low Pressure Handwand: 40 gallons when mixing/loading/applying liquids, or application to 5 acres;

A study was submitted by Dow AgroSciences, “Chlorpyrifos Peach Tree Root Dip Application and Wor ker Exposure Study (MRID 463655 01) and reviewed by HED. This study, which was based upon the interview of 51 peach tree growers, was conducted to provide information for the assessment of worker exposure when peach tree seedlings are dipped prior to transplanting. Based on this review, HED has determined that root dipping is a very minor use pattern, with acreages for peach tree planting operations ranging from 1 to 150. The average hours spent by an individual during dipping application is estimated at 5.3 hours per occurrence. The majority of peach tree growers either did not dip their trees or only did so on a once in 5

- 8 year frequency. For the purpose of quantitative risk assessment HED will assume the maximum acreage identified per application, 150. Because the use patte rn is minor and done so infrequently, duration of exposure is anticipated to be short

- term only;

Paint Roller/Brush: 110 gallons for sewer manhole wall covers (2, 55 gallon drums), 3 gallons applied for all other uses;

Cattle Ear Tag: 100 ear tags ap plied (100 cattle, at 1 tag per head ) ;Page 28 of 107

Roach Bait Station: 100 stations applied;

Total Release Fogger: 4 cans applied;

Drench/Dip: 1,000 gallons for applications to soil in containers; 100 gallons for root dip applications (MRID 4636555 01);

Shaker Container and Open Pour Bag: 1,000 square feet applied by hand dispersal to treated area;

Push Type Spreader: 5 acres treated per application;

Fire Ant Mounds: 25 mounds;

Belly Grinder: 1 acre treated per application.

2.1.2 Exposure Data for Handler Exposure Scenarios

HED uses unit exposure to assess handler exposures to pesticides. Unit exposures are estimates of the amount of exposure to an active ingredient a handler receives while per forming various handler tasks and are expressed in terms of micrograms or milligrams of active ingredient per pounds of active ingredient handled. HED has developed a series of unit exposures that are unique for each scenario typically considered in our a ssessments (i.e., there are different unit exposures for different types of application equipment, job functions, and levels of protection).

The unit exposure concept has been established in the scientific literature and also through various exposure moni toring guidelines published by the U.S. EPA and international organizations such as Health Canada and OECD (Organization for Economic Cooperation and Development). HED identified 3 major surrogate unit exposure data sources for assessment of

occup ational handler exposure/risk. These data sources include:

PHED (Pesticide Handlers Exposure Database); Outdoor Residential Exposure Task Force (ORETF); and Agricultural Handlers Exposure Task Force (AHETF).

In addition to surrogate data, 2 non

- chemical spec ific exposure studies and 5 chemical specific handler exposure (biomonitoring and passive dosimetry) studies that were submitted in support of chlorpyrifos re

- registration and have been reviewed and considered for use by the HED. The

non

- chemical specific exposure studies (described in detail below) were us ed when either exposure data were lacking or it was deemed the best available data source for assessment of the exposure scenario.

Based on HED‟s review of the 5 chemical specific studies, a number of issues were identified which limit the utility of the available data. These include: the sufficiency of sample size, PPE worn by study participants, sufficient risk mitigation is not provided (e.g., additional PPE or engineering controls), and the studie s do not en compass all handler uses of chlorpyrifos. Due toPage 29 of 107

the limitations outlined, HED has determined that these data are most useful as a tool for comparison to those estimates generated for representative exposure scenarios using surrogate

data. A full description of the issues, a summary of the studies and the results of the comparative analysis are presented in Section 2.2, Occupational Handler Comparison Using Biomonitoring Data

.

A detailed description of the data source selected for each expo sure scenarios assessed is presented in Appendix A/Table 2 which accompanies this document . Unit exposure values as selected from these exposure data sources at each level of personal protection and engineering control are presented in Appendix A/Table 3. Below are brief descriptions of the data sources

used.

PHED Version 1.1 (August 1998): PHED was designed by a task force of representatives from the U.S. EPA, Health Canada, the California Department of Pesticide regulation, and member companies of th e American Crop Protection Association. PHED is a software system consisting of two parts

– a database of measured exposures for workers involved in the handling of pesticides under actual field conditions and a set of computer algorithms used to subset a nd statistically summarize the selected data. Currently, the database contains values for over 1,700 monitored individuals (i.e., monitoring units).

Users select criteria to subset the PHED database to reflect the exposure scenario being

evaluated. The subsetting algorithms in PHED are based on the central assumption that the magnitude of handler exposures to pesticides are primarily a function of activity (e.g., mixing/loading, applying), formulation type (e.g., liquids, granulars), application method (e.g., aerial, groundboom), and clothing scenarios (e.g., gloves, double layer clothing).

Once the data for a given exposure scenario have been selected, the data are normalized (i.e., divided by) by the amount of pesticide handled resulting in standard u nit exposures (milligrams of exposure per pound of active ingredient handled). Following normalization, the data are statistically summarized. The distribution of exposure for each body part (e.g., chest, upper arm) is categorized as normal, lognormal, o r “other” (i.e., neither normal nor lognormal). A central tendency value is then selected from the distribution of the exposure for each body part. These values are the arithmetic mean for normal distributions, the geometric mean for lognormal

distributi ons, and the median for all “other” distributions. Once selected, the central tendency values for each body part are composited into a “best fit” exposure value representing the entire body.

The unit exposures calculated by PHED generally range from the geometric mean to the median of the selected data set. To add consistency and quality control to the values produced from this system, the PHED Task Force has evaluated all data within the system and has developed a set of grading criteria to characteriz e the quality of the original study data. The assessment of data quality is based on the number of observations and the available quality control data. While data from PHED provide the best available information on handler exposures, it should be noted t hat some aspects of the included studies (e.g., duration, acres treated, pounds of active ingredient handled) may not accurately represent labeled uses in all cases. HED has developed a series of tables of standard unit exposure for many occupational scen arios that can be utilized to ensurePage 30 of 107

consistency in exposure assessments. Unit exposures are used which represent different levels of personal protection as described above. Protection factors were used to calculate unit exposures for varying levels of p ersonal protection if data were not available.

ORE TF Handler Studies (MRID 449722 01): A report was submitted by the ORETF (Outdoor Residential Exposure Task Force) that presented data in which the application of various products used on turf by homeowner s and lawncare operators (LCOs) was monitored. All of the data submitted in this report were completed in a series of studies. Unit exposures fro m the following ORETF studies were used in this assessment and are summarized in a 4/30/01 HED memo (G. Bangs , D261948). The following studies were used to assess chlorpyrifos occupational handler exposure:

ORETF Study OMA001

- monitoring of LCO exposure scenarios while using a granular spreader ORETF Study OMA002

- monitoring of LCO exposure scenarios using a low pressure, high volume turf handgun

Table 2.1.2a below presents the ORETF unit exposure values used in the assessment of chlorpyrifos occupational handler exposure.

Table 2.1.2a: Unit Exposure Values Obtained from ORETF Studies (MRID 449722 01)

Ty pe Units (mg exposure/lb ai handled)

Dermal

Inhalation Single Layer,

Gloves Single Layer,

Gloves Double Layer,

Gloves

LCO Push Granular Spreader (OMA001) 0.35 0.22 0.11 0.0071

LCO Turfgun (WP Formulation) (OMA002) No Data 0.65 0.36 0.0066

All unit exposure values are geometric means except inhalation value for granular spreader. Double layer value calculated using a 50% protection factor. Turf gun, no glove data were not back calculated using a 90 percent protection factor as it is deemed unreliab le. Inhalation unit exposure values represent no respiratory protection as respirators are not considered feasible in the outdoor residential settings and, therefore, were not measured.

AHETF: AHETF is a consortium of 24 agricultural chemical compani es (which includes the primary registrant of chlorpyrifos, Dow AgroSciences) that formed a joint data development task force to design and develop a database on exposure of agricultural workers during the mixing, loading and/or application of pesticides. The data generated covers several types of mixing/loading systems, types of application equipment and types of formulations. Currently, the Agency has reviewed three studies conducted and submitted by t he AHETF. HED has

confirmed that the studies meet th e study design benchmarks outlined in the AHETF Governing Document (AHETF, 2007) and is considered to be the most reliable data for assessing exposure and risk for these exposure scenarios. Of the studies reviewed, two were applicable to and used

for the assessment of occupational dermal and inhalation chlorpyrifos exposure potential. Reviews of the studies are summarized in the documents, “ Health Effects Division (HED) Review of Agricultural Handler Exposure Task Force (AHETF) Monograph: Open Pour Mixin gPage 31 of 107

and Loading Liquid Formulations (D373605, 3/11/11 )” and “ Health Effects Division (HED) Review of Agricultural Handler Exposure Task Force (AHETF) Monograph: Open Cab Ground Boom Application of Liquid Sprays (D373605, 3/11/11 ).” The study, Open Pour Mix ing and Loading Dry Flowable Formulations (MRID 47947801 ) has also been reviewed by HED , but no dry flowable formulation is registered for chlorpyrifos occupational use. The AHETF scenarios

were posted and are publically available on the EPA website as of 4/8/2011 ( http://www.epa.gov/pesticides/science/handler

- exposure

- data.html ).

Table 2.1.2b below presents the AHETF unit exposure values used in the assessment of chlorpyrifos occupational handler exposure.

Table 2.1.2b: Unit Exposure (ug /lb ai handled): Open Pour Mixing and Loading Liquids Exposure Scenario Dermal Inhalation
SL_G DBL_G NR PF5 PF10 Open Pour Mixing and Loading Liquids 37.6 29.1 0.219 0.044 0.022

Open C ab Groundbom Application of Liquid Sprays 16.1 12.6 0.34 0.068 0.034

Non

- Chemical Specific Exposure Data:

MRID 447933 01/Exhibit 2 (15G Study): Exposure of Farmworkers To Terbufos (CL 92100) While Loading COUNTER 15G Systemic Insecticide

- Nematicide Wit h A Lock

- N

- Load Closed Handling System And Applying COUNTER 15G To Corn At Planting Time ; (3/26/99) Authored by Joseph Higham; Completed by ABC Laboratories of Columbia MO, Agrisearch of Frederick MD, and American Cyanamid of Princeton NJ.; Project ID #s i nclud e: Exhibit 2 of

EPA MRID 447933 01, Terbufos 99

- 02, EXA 99

- 004, EXA 99

- 006, and RES 99

- 003, Sponsored by American Cyanamid.

The field portion of this study was conducted at 15 sites in central Nebraska during the 1998 growing season. All totaled, 30 individual farm workers were monitored in this study. At each site, two farm workers (one loaded and the other completed the application) were monitored during the application, with soil incorporation, of terbufos 15G using “Lock

- N

- Load” type packaging, t ypical corn planters, and closed cab tractors (open cabs were used for 2 replicates). All planters were either 6 or 8 row devices. Corn was treated at an average application rate of 1.23 lb ai/acre (the label maximum is 1.3 lb ai/acre) at planting. The total amount of active ingredient loaded in this study ranged from 66 to 96 pounds while the total amount of active ingredient applied in this study ranged from 35.8 to 81.9 pounds. The exposure time periods for loaders ranged from 0.37 to 0.78 hours whil e the time periods for the applicators ranged from 3.8 to 8.7 hours. Exposure monitoring for dermal and inhalation exposure was completed using

whole

- body dosimetry, aqueous handwashes, aqueous glove washes, facial/neck wipe, inhalation monitoring in the breathing zone using personal sampling pumps, and inhalation monitoring in the breathing zone using personal sampling pumps pulling air through a respirator cartridge attached to the sampling device. All data except for the glove washes and the respirator cartridge protected inhalation monitoring data were used in the risk assessment. These data were not used in the assessment because the monitoring techniques are not considered to be acceptable approaches by the Agency.Page 32 of 107

The loaders in this study used th e “Lock

- N

- Load” type packaging as described above. Additionally, they wore normal work clothing, nitrile gloves, and a chemical

- resistant apron (i.e., treated as a double layer of protection by the Agency for the purposes of this assessment). The applica tors in this study used closed cabs as described above. Additionally, they wore normal work clothing, nitrile gloves, coveralls, protective eyewear, and an air purifying respirator with and organic vapor removing cartridge.

The analytical results of th is study indicate that terbufos was present in the 15G formulation used to make all applications in the study (avg = 105 % of the nominal 15 w/w concentration) and that

terbufos was stable over time in the solutions used to dose the field fortification sam ples (avg = 99.6 % of nominal). The detection and quantification limits established in the study and verified by the Agency are as follows:

Exposure Media Detection Limit Quantification Limit

Air Tubes 4.0 (ng/sample) 20.0 (ng/sample)

Whole

- Body Dosime ters 0.20 (μg/sample) 1.0 (μg/sample)

Handwashes 0.10 (μg/sample) 0.50 (μg/sample) Face/neck wipes 0.10 (μg/sample) 0.50 (μg/sample)

Laboratory recovery data are generated to ensure the daily performance of an analytical method during the analysis of f

ield samples. The laboratory recovery data for each media from this study are summarized in the table below:

Exposure Media Fortification Range (μg/sample) N Results [ avg ± sd (%) & CV ]

Air Tubes 0.020

– 2000 12 88 ± 16 CV = 18.2

Whole

- Body

Dosimet ers 1.0

- 25.0 18 92 ± 18 CV = 19.6

Handwashes 0.5

- 2.5 17 88 ± 11 CV = 12.5

Face/neck wipes 0.5

- 5.0 10 94 ± 9.4 CV = 10.0

Field and storage stability recovery data are generated to ensure the stability of residues during field sampling and ov er storage until analysis. In this study, the field recovery samples also provided data for storage stability as the samples were generated, stored, and analyzed concurrently with the field samples. The field recovery data for each media from this study are summarized in the table below:

Exposure Media Fortification Range (μg/sample) N Results avg ± sd (%) & CV

Air Tubes 0.05

- 1.00 18 62 ± 16 CV = 25.8

Whole

- Body

Dosimeters 5.0

- 10.0 18 86 ± 8.0 CV = 9.3

Handwashes 2.5

- 5.0 18 79 ± 8.4 CV = 10.6 Face/neck wipes 2.5

- 5.0 18 62 ± 5.5 CV = 8.9Page 33 of 107

Unit exposures were calculated and verified by the Agency. These values were used for risk assessment purposes by the Agency. The values were calculated by correcting for the average field recovery values summarized above. The unit exposure values used by the Agency in the risk assessment were only based on the use of protective gloves (i.e., glove wash data were not used in the risk assessment) and the use of no respiratory protection (i.e., inhal ation monitoring data generated by pulling air through a respirator cartridge was not used in the risk assessment). The unit exposure values used in the assessment reflect only the use of closed cabs during application.

The results of this study indicate very low exposure levels as would be expected given the exposure scenarios that were monitored (i.e., lower exposure activities with high levels of personal protection). There was a high percentage of values that were less than either the limit of

detect ion (LOD) or limit of quantification (LOQ). In such cases, the values used to calculate the unit exposure values were either 1⁄2 of the LOD or LOQ as appropriate. The nondetect values presented in the table below fit both categories. It should be noted, h owever, that a majority of

the whole

- body dosimeters contained detectable residues of terbufos. These study results are summarized in the following table:

Table 2.1.2c: Unit Exposure Values Obtained from Tractor Closed Loading and Application Study of Granular Formulation (MRID 447933 01)

Job Function Data Type Dermal Data Inhalation Data Unit Exposure (mg/lb ai) Nondetects

(%) Unit Exposure

(mg/lb ai) Nondetects

(%)

Loaders 1 Minimum 1.21x10
- 5

WBD: 6.7

HW: 93.3

FNW: 100 5.28 x10
- 7

46.7 Ge o. Mean 5.20 x10
- 5 7.84 x10
- 6

Maximum 3.61x10
- 4 6.50 x10
- 5

Applicators 2 Minimum 7.32 x10
- 6

WBD: 33.3

HW: 93.3

FNW: 100 4.25 x10
- 7

100 Geo. Mean 3.51 x10
- 5 2.43 x10
- 6

Maximum 1.65 x10
- 4 2.04 x10
- 5

1 Unit exposure data for lo aders are based upon workers wearing double layer clothing, chemical resistant gloves and no respirator.

2 Unit exposure data for applicator are based upon workers wearing double layer clothing, chemical resistant gloves, and PF10 respirator.

WBD = whole

- body dosimeter, HW = handwash, FNW: face and neck wipe

MRID 452507

02: Worker Exposure Study during Application of Regent 20GR in Banana

Plantation:

A total of 18 mixer/loader/applicator events during granular backpack (i.e., a specialized device

manu factured by Horstine Farmery) or spoon application of fipronil to bananas were monitored during applications on three different days in June, 1994 on the same banana plantation in Cameroon. [Note: Only the spoon application data included in this study are used in the carbarylPage 34 of 107

risk assessment as backpack granular applications have been assessed using the data presented above.] The 18 replicates were distributed over the 3 sampling days as follows: 6 spoon/hand applications on day 1; 4 spoon/hand applications on day 2; and 8 backpack events on day 3. Weather was typical of the application season in that it was hot and humid. Monitoring was completed using whole body dosimeters, cotton gloves, cotton caps, and personal sampling pumps equipped with filters. Rege nt 20GR was supp lied in 22 pound boxes which were loaded directly into the backpack devices or buckets for the spoon applicators. The application rate for fipronil used in this study is 7.5 grams of Regent 20GR (i.e., 0.15 grams ai/plant) which is equivale nt to about 0.26 lb ai/acre (0.00033 lb ai/plant) at approximately 800 plants per acre. The numbers of acres treated ranged from approximately 0.75 to 1 acre. The pounds of active ingredient handled ranged from about a quarter to half a pound per replicate . Each applicator wore whole body dosimeters that also served as the normal work clothing. PVC gloves were also worn over cotton gloves which served as the dosimeters. A protection factor of 50 percent was used by the Agency to calculate exposure levels un der a layer of normal work clothing. Dosimeter samples were segmented into arms, legs, and torso for analysis.

Analysis of fipronil residues was completed with gas chromatography and electron capture detection. The limits of quantification (LOQ) were 9.7 μg per sample for all media used. The limit of detection (LOD) varied for each media. The LOD for the cotton gloves was 0.5 μg per sample, 0.10 μg per sample for the air filters, and 2.0 to 4.0 μg per sample for the whole body dosimeters depending upon the sample analyzed. Field and laboratory recovery data were generated for all media. Field recovery data were generated in a manner that addressed field sampling, field storage, transport, laboratory storage, and analysis. However, the laboratory recovery da ta were indeterminate because the sample media could not be identified for each reported result. The overall recovery values do appear to be quantitative. Residues were corrected for the overall average field recovery for each residue/matrix combination. G enerally, recovery was adequate for all media/residue combinations (i.e., all correction factors were greater than 85 percent).

Unit exposure values were calculated using the data from the study and a co mmercial spreadsheet program. The exposures that we re calculated w ere normalized by the amount of chemical used, the duration of the application interval, and by th e body weight of the individual applicators (see table below). The values are based on a 50 percent clothing penetration factor

and are separat ed for each equipment type monitored in this study. For each normalization factor,

the arithmetic mean, geometric mean, and various percentiles we re calculated. No analyses were completed with these data to ascertain the exact type of distribution . The Age ncy typically uses

the best fit values from the Pesticide Handlers Exposure Database w hich are representations of

the central tendency. Considering the standard practice, the Agency will use the geometric mean for risk assessment purposes.

Table 2.1.2.d: Unit Exposures Obtained From Fipronil Spoon Application Study ( MRID 452507 02 )

Type Dermal (mg ai/lb handled) Inhalation (μg ai/lb handled)

Geometric Mean 1.98 45.0Page 35 of 107

2.1.3 Occupational Handler Exposure Scenarios

It has been determined that exposu re to pesticide handlers is likely during the occupational use of chlopyrifos in a variety of occupational environments. The anticipated use patterns and current labeling indicate several occupational exposure scenarios based on the types of equipment and techniques that can potentially be used for chlorpyrifos applications. The quantitative exposure/risk assessment developed for occupational handlers is based on the following

scenarios:

Mixer/Loaders:

(1a) Liquids for Aerial/ Chemigation Applications (1 b) Liquids for Airblast Applications (1c) Liquids for Groundboom Applications (1d) Liquids for Wide Area Aerial Applications (1e) Liquids for Wide Area Ground Applications (2a) Wettable Powder (in WSP) for Aerial/ Chemigation Applications (2b) Wettable Pow der (in WSP) for Airblast Applications (2c) Wettable Powder (in WSP) for Groundboom Applications (3a) Granulars for Aerial Applications (3b) Granulars for Tractor Drawn Spreader Applications (3c) Granulars with SmartBox® for Aerial Applications (3c) Granul ars with SmartBox® for Tractor Drawn Spreader Applications (4a) Water Dispersible Granulars (in WSP) for Aerial/ Chemigation Applications (4b) Water Dispersible Granulars (in WSP) for Airblast Applications (4c) Water Dispersible Granulars (in WSP) for Grou ndboom Applications

Applicators:

(5a) Aerial Liquid Applications (5b) Wide Area Aerial Applications (5c) Aerial Granular Applications (6a) Airblast Applications (6b) Wide Area Ground Applications (7a) Groundboom Applications (7b) Tractor

- drawn Granular A pplications (7c) SmartBox® Applications (8) Paint Brush/Roller Applications (9) Cattle Ear Tag Applications (10) Bait Station Applications (11) Total Release Fogger

Mixer/Loader/Applicators:

(12a) Liquid: Low Pressure Handwand Sprayer (12b) Liquid: Wett able Powder (in WSP) for Low Pressure Handwand SprayerPage 36 of 107

(12c) Liquid: Microencapsulated for Low Pressure Handwand Sprayer (12d) Liquid: Backpack Sprayer (12e) Liquid: Wettable Powder (in WSP) for Backpack Sprayer (12f) Liquid: Microencapsulated for Backpa ck Sprayer (12g) Liquid: High Pressure Handwand Sprayer (12h) Liquid: Handgun Sprayer (12i) Liquid: Wettable Powder (in WSP) for Handgun Sprayer (12j) Liquid: Microencapsulated for Handgun Sprayer (12k) Liquid: Drench/Dip (12l) Liquid: Paint/Brush Ro ller (13a) Granulars: Shaker Container (13b) Granulars: Open Pour Bag (13c) Granulars: Push Type Spreader (13d) Granulars: Bucket and Spoon (13e) Granulars: Belly Grinder (14a) Water Dispersible Granular (in WSP): Low Pressure Handwand Sprayer (14b) Wate r Dispersible Granular (in WSP): Backpack Sprayer (14c) Water Dispersible Granular (in WSP): Handgun Sprayer

Flaggers:

(15a) Flagging for Aerial Spray Applications (15b) Flagging for Aerial Granular Applications

2.1.4 Occupational Handler Exposure an d Risk Calculations

Chlorpyrifos occupational handler exposure and risk were calculated using the Margin of Exposure (MOE) approach, which is the ratio of the body burden to the t oxicological endpoint of concern. Estimates of body burden are calculated considering application parameters (i.e., rate and area treated daily) along with unit exposures selected for the exposure scenario. Exposures are normalized by body weight and adj usted for absorption factors as appropriated to calculate

dose levels.

Daily Exposure: Daily dermal or inhalation handler exposures are estimated for each applicable handler task with the application rate, the area treated in a day, and the applicable d ermal or inhalation unit exposure using the following formula:

Daily Exposure (mg ai/day) =

Unit Exposure (mg ai/lb ai) x Application Rate (lb ai/A) x Daily Acres Treated (A/day)

Where:

Daily Exposure = Amount (mg or μg ai/day) deposited on the sur face of the skin that is available for dermal absorption or amount inhaled that is available for inhalation absorption;Page 37 of 107

Unit Exposure = Unit exposure value (mg or μg ai/lb ai) derived from exposure data; Application Rate = Normalized application rate bas ed on a logical unit treatment, such as acres, square feet, or gallons. Maximum values are generally used (lb ai/A, lb ai/sq ft, lb ai/gal) and Daily Area Treated = Normalized application area based on a logical unit treatment such as acres (A/day), squar e feet (sq ft/day), OR gallons per day (gal/day).

Daily Dose: The daily dermal or inhalation dose is calculated by normalizing the daily exposure by body weight and adjusting, if necessary, with an appropriate dermal or inhalation absorption

factor. Fo r all short

- and intermediate

- term exposure scenarios for chlorpyrifos, an average adult body weight of 70 kilograms was used, since the toxicological endpoint of concern (i.e., p lasma ChE and RBC AChE inhibition) is not sex

- specific. An absorption rate w as not used for short

and intermediate

- term dermal risk assessment because the short

- and intermediate

- term toxicological endpoint is derived from a dermal study. Because the short

- and intermediate

- term inhalation endpoints are based on an inhalation stu dy, no absorption factor is necessary. Daily dose was calculated using the following formula:

Average Daily Dose (mg ai/kg/day) = Daily Exposure (mg ai/day) x ( Absorption Factor (%/100 ) Body Weight (kg)

Where:

Average Daily Dose = Absorbed dose received from exp osure to a pesticide in a given scenario (mg pesticide active ingredient/kg body weight/day); Daily Exposure = Amount (mg ai/day) deposited on the surface of the skin that is available for dermal absorption or amount inhal ed that is available for inhalation absorption; Absorption Factor = A measure of the amount of chemical that crosses a biological boundary such as the skin or lungs (% of the total available absorbed); and Body Weight = Body weight d etermined to represent the population of interest in a risk assessment (kg).

Margins of Exposure: Dermal and inhalation risks for each applicable handler scenario are calculated using a Margin of Exposure (MOE) approach, which is a ratio of the dai ly dose to the toxicological endpoint of concern. All MOE values were calculated separately for dermal and inhalation exposure levels using the formula below:

MOE = NOAEL or LOAEL (mg ai/ (kg/day)) Average Daily Dose (mg ai/ (kg/day))

Where:

MOE = Margin of Exposure, value used by HED to represent risk or how close a chemical exposure is to being a concern (unitless);

ADD = Average Daily Dose or the absorbed dose received fromPage 38 of 107 exposure to a pesticide in a given scenario (mg pesticide ac tive ingredient/kg body weight/day); and

NOAEL or LOAEL = Dose level in a toxicity study, where no observed adverse effects (NOAEL) or where the lowest observed adverse effects (LOAEL) occurred in the study

Risk values are presented for each route of ex posure (i.e., dermal or inhalation) in each scenario, because risk mitigation measures are specific to the route of exposure. In addition, dermal and inhalation risk estimates are combined when toxicity endpoints are the same.

The LOC for short

- and in termediate

- term occupational dermal exposure ( defined as an MOE =

1 00) differs from the LOC for short

- and intermediate

- term occupation inhalation exposure ( defined as an MOE = 3 0 ). A n ARI is required to combine or aggregate risk from differing

routes of exposure when the LOCs are not the same. EPA identifies as a level of concern ARIs

that fail to reach or exceed the level of 1. Lower ARIs raise a risk of concern. The following

formula was used to calculate an ARI:

Aggregate Risk Index (ARI) = 1 / ((1/estimated MOE for dermal exposure/ LOC for dermal exposure (MOE = 100 ) ) + (1/estimated MOE inhalation exposure/ LOC for inhalation exposure (MOE = 30 ))

2.1.5 Occupational Handler and Exposu re Risk Summary

S hort

- and intermediate

- term occupational handler exposure/risk estimates are presented in Appendix A/Table 1 which accompanies this document . Risk estimates consider all levels of personal protective equipment and engineering controls us ing surrogate data from AHETF,

ORETF and PHED.

Of the 305 exposure scenarios assessed, 134 were not of concern at some level of personal protection (i.e., an ARI > 1). Ninety

- one (91) exposure scenarios were not of concern when engineering controls wer e considered. The remaining 80 scenarios resulted in risks of concern to HED (i.e., an ARI < 1) at all levels of personal protection and engineering controls considered.

2.1.6 Summary of Occupational Handler Exposure Data Gaps

No new data gaps have bee n identified for the assessment of occupational handler exposure/risk

in addition to those identified in the Registration Eligibility Decision (RED) for chlorpyrifos ( finalized 7/31/06 ; IRED issued 2/2002)

. Based on a 90

- day progress report submitted (Aug ust 28, 2003) by the technical registrant, Dow AgroSciences, many of the data requirements are anticipated to be supported by the generation of data by the Agricultural Handlers Exposure Task Force (AHETF). These data requirements include:

Exposure dat a for seed treatment uses; Exposure data for mixing wettable powders for aerial/chemigation application; Exposure data for loading and applying granulars for aerial application ; Exposure data for groundboom application; andPage 39 of 107

H uman flaggers for aerial appl ication.

AHETF data for groundboom application and for mixing/loading liquid formulations have been submitted and reviewed by HED and used to estimate exposure/risk for occupational handlers from the exposure scenario and, therefore, satisfy the data re quirement. AHETF data for seed treatment and planting treated seed has been submitted and is currently under review by HED. The requirement for exposure data for mixing wettable powders for aerial/chemigation applications should be waived because the form ulation is no longer supported by the registrant. An exposure study for loading granular formulations is being planned under AHETF

.

The remaining data requirements were addressed as well in the Dow AgroSciences 90

- day progress report (8/28/03). The fol lowing describes the data requirement, the update from the progress report and current status:

Exposure data for dip applications (e.g., preplant peaches)

Data w ere submitted by Dow AgroSciences, (MRID 46365501) Robertson, A. (2004) Chlorpyrifos Pea ch Tree Root Dip Applic ation & Worker Exposure Study. Project Number: ASR091604. Unpublished stud y prepared by Dow AgroSciences LLC. 8 p. HED has reviewed this usage data and determined that the data requirement has been satisfied.

Risk Assessment data for treated wood in residential structures.

Data w ere submitted by Dow AgroSciences, (MR ID 46207702) Selman, F. (2004) Potential Exposure and Risk to Inhabitants of Homes Where Door and Window Frames Are Constructed

with Lumber that has Been Pressure Trea ted with Chlorpyrifos. Project Number: GH/C/5720. Unpublished study prepared by Dow AgroSciences, LLC. 13 p. HED has reviewed these data and determined that the requirement has been satisfied.

Use pattern information for hydraulic handheld spray appli cations (amounts handled per day, per season; types of sprayers used).

In the 90

- day progress report, Dow AgroSciences provided that, “the USDA Forest Service will develop usage data to confirm the actual amount of chlorpyrifos used on a daily and season al basis. They will also provide additional information describing the types of sprayer used in order

for EPA to refine risk assessments. The final report will be completed and submitted to the EPA by the Forest Service by November 28, 2003 and DAS wil l cite these data.” As of a February 2011 OPPIN Database search, no data have been submitted by Dow AgroSciences from the USDA Forest Service report. Therefore, this data requirement is not currently satisfied.

Use pattern information for high pressure hand

- wand spray applications (amounts handled per day, per season; types of sprayers used).

In the 90

- day progress report, Dow AgroSciences described that it was “working with the American Nursery and Landscape Association to provide actual use informati on and data for this application. We will cite data from the Agricultural Chemical Use

– 2000 Nursery andPage 40 of 107

Floriculture Summary published April 2002 by USDA. These data will indicate that chlorpyrifos is used intermittently in small blocks or areas as a r otational tool and actual use is typically less than 100 gallons per day.” As of a February 2011 OPPIN Database search, no data have been submitted by Dow AgroSciences from the USDA Nursery and Floriculture Summary report. Therefore, this data requiremen t has not been satisfied.

Usage data to confirm the acres treated on sod farms for mole crickets.

In the 90

- day progress report, Dow AgroSciences described that “DAS is developing a survey for sod farm managers to determine actual use data for use of chlorpyrifos to control mole crickets. These data can then be used by EPA to refine risk estimates. The present EPA assumption of 80 acres treated per day is an overestimate for this particular use.” As of a February 2011 OPPIN Database search, no d ata have been submitted by Dow AgroSciences in support of this data requirement. Therefore, this data requirement has not been satisfied.

Exposure data for backpack spray application.

No data have been submitted by Dow AgroSciences in support of this da ta requirement. However, HED has determined that the PHED data exposure data available and used to assess this exposure scenario are acceptable and no data will be required.

2.1.7 Occupational Handler Characterization

The occupational handler exposur e and risk assessment for chlorpyrifos is based upon an array of calculations completed for all identified exposure scenarios using the short

- and intermediate

term endpoints. HED completes both short

- and intermediate

- term assessments for occupational

sc enarios in essentially all cases, because exposures of these durations are likely and acceptable use/usage data are not available to justify deleting intermediate

- term scenarios. HED identified

305 different exposure scenarios which are defined based on t he equipment used to make applications or the type of formulation used. Within each of these categories, different application rates and acres treated values were considered to evaluate the broad range of applications that may occur with each kind of equi pment (e.g., a groundboom may be used for turf or agriculture). Finally, it should be noted that each calculation was completed at different levels of personal protection to allow for a more informed risk management decision. Even given the scope of the calculations that have already been completed, it is possible that some uses of chlorpyrifos that have not been quantitatively addressed in this document either due to lack of exposure data or other information and because chlorpyrifos is such a widely use d

chemical.

The data used in the chlorpyrifos occupational handler risk assessment represent the best data and approaches that are currently available. While some of the data which have been used may not be of optimal quality, they represent the best a vailable data for the scenario in question. In many cases, the Pesticide Handlers Exposure Database (PHED) was used to develop the unit exposure values. PHED data quality varies widely from scenarios that meet guideline requirements for studies to others where a limited number of poor quality data points are available. The results for each scenario should be reviewed in the context of the quality of thesePage 41 of 107

data. PHED unit exposure values represent a central tendency of the data (i.e., geometric mean,

med ian or arithmetic mean depending upon the distribution of the data). As such, the values based on the recent studies also are measures of central tendency (e.g., the geometric means were selected from each study for assessment purposes in most cases). HE D used recently developed data from AHETF to assess the exposure scenarios mixing/loading liquid formulations and application of liquid sprays via open cab groundboom. HED has reviewed the data for the two studies and has confirmed that it meets study des ign benchmarks outlined in the AHETF Governing Document (AHETF, 2007) and is considered the most reliable data for assessing exposure and risk for these exposure scenarios. The efforts undertaken by AHETF represent a

well

- designed, concerted process to co llect reliable, internally

- consistent, and current exposure data in a way that takes advantage of and incorporates a more robust statistical design, better analytical methods, and improved data handling techniques. For the purpose of the assessment

of the two exposure scenarios, HED has used the arithmetic mean unit exposure for short

- and

intermediate

- term exposure durations as recommended in the study review s (D373605 ).

Along with the unit exposure values used in the assessment, other inputs include a pplication rates and daily acres treated values. The application rates selected for occupational handler risk assessment represent the maximum amounts that are allowed by the label for all uses. The application rates that were selected for use in the ris k assessment were defined based on a review of all current labels. The other key input for completing handler risk assessments used for defining how much chemical can be used in a day is how much can be treated in a day which is generally expressed as the number of acres treated per day. The values used for this parameter represent the HED‟s most current thinking.

In addition to the key sources of information considered above, there are many underlying factors that may impact the overall results of a ri sk assessment. For example, the protection factors used for adding additional levels of dermal and respiratory protection may impact the overall risk picture. The factors used in this assessment by HED have been in use for many years. There are exposure monitoring issues which must be considered. For example, in many cases the data included in PHED are based on the use of cotton gloves for hand exposure monitoring which is thought by many to have the potential to overestimate exposure because they poten tially retain residue more than a bare hand would over the course of a work day. Such intangible elements of the risk assessment reflect many of the hidden uncertainties associated with exposure data.

In summary, HED believes that the risk values prese nted in this occupational assessment represent the highest quality results that could be produced given the exposure, use, and toxicology data that are available. Risk managers and other interested parties should consider the quality of individual inputs when interpreting the results and make decisions accordingly. It is difficult to ascertain at what point on a distribution the values which have been calculated fall because the distributional data for exposure, application rates, acres treated and many o ther parameters are unrefined. HED does believe, however, that the risks represent conservative estimates of exposure because maximum application rates are coupled with high acreage estimates to define risk estimates that likely fall in the upper percenti les of the actual exposure distributions. Additionally, risk estimates are thought to be conservative even when measures ofPage 42 of 107

central tendency are combined because values that would be considered to be in the lower percentile aspect of any input parameter h ave not been used in the calculations.

2.2 Occupational Handler Comparison Using Biomonitoring Data

Occupational handler exposure estimates as presented in Section 2.1 were estimated based on surrogate data from AHETF, ORETF and PHED, as well as 2 non

- c hemical specific studies . In

addition to these data , 5 chemical specific handler exposure studies submitted in the past in support of chlorpyrifos re

- registration were reviewed and considered for use by the HED. Risk estimates have been calculated using absorbed doses (mg/ kg ) measured from the biomonitoring studies determined to be acceptable for quantitative risk assessment purposes. In order to characterize occupational risk estim ates calculated using surrogate, passive dosimetry exposure data, HED has presented a comparative analysis of these data and biomonitoring data available for applicable exposure scenarios. Based on HED policy and consistent with Section 2.1, a short

and intermediate

- term assessment was completed for all occ upational scenarios because

e xtended periods of exposure are likely and acceptable use/usage data are not available to justify removing intermediate

- term scenarios and the dermal toxicity point of departure is the same for

both durations

. Evaluation of biomonitoring data was conducted based on a comparison of the absorbed dose as measured by urinary excretion of 3,5,6

- trichloro

- 2

- pyridinol (TCP), to the oral equivalent NOAEL of 0.15 mg/kg/day (i.e., 5 mg/kg/day from 21

- day dermal study x 0.03 dermal absorption) because the ma jority of exposure is via the dermal route.

Occupational handler exposure/risk was estimated consistent with the methods presented in Section 2.1.1 and the methods as described in Section 2.1.4 above and makes use of the exposure data as presented in th e Section 2.2.1 below. Comparative estimates using chemical specific handler exposure studies are limited to the level of clothing and personal protection worn by the participants when the studies were conducted. Comparative short

- and intermediate term occupational handler exposure/risk using biomonitoring and surrogate exposure data are presented in Appendix B which accompanies this document

.

All chemical specific exposure studies required review for ethical conduct, received that review

and all but o ne were determined to be ethical relevant to the standards of the time that the studies were conducted. In addition, all studies were reviewed as to their relevance in the current market in regard to product formulation. Based on this analysis, one study measured the mixing/loading of a wettable powder formulation which is no longer supported by the product registrant. Despite this limitation, the application of the mixed wettable powder formulation was considered

for use because the formulation was mixe d into a liquid form and is, therefore an acceptable surrogate. HED considered use of the 4 remaining handler exposure studies and weighed the strengths and weaknesses of each. A number of issues limit the utility of the studies, including:

the sufficien cy of sample size, PPE worn by study participants, sufficient risk mitigation is not provided (e.g., additional PPE or engineering controls), and the studies do not encompass all

handler uses of the chemical.

The number of monitored workers across the 4 studies range from 15 to 1. HED has typically relied on the criteria set forth by the Pesticide Assessment Guideline which recommend 15

exposure measurements as a minimum for each exposure scenario . Only 1 of the 4 studies meetsPage 43 of 107

this criterion. For exam ple, a mixer/loader/applicator greenhouse study (MRID 430279 01) attempted to monitor 6 different greenhouse handler scenarios and, as a result was only able to collect 5 measurements for 2 exposure scenarios, 3 for another, and only 1 for each of the

remai ning 3 scenarios.

Workers participating in the 4 reviewed studies wore a wide range of clothing and personal protective equipment. All workers wore an inner dosimeter which included t

- shirt and briefs used to measure the penetration of chlorpyrifos thr ough the outer dosimeter. The outer dosimeter was typically represented either by coveralls, or long sleeved shirt and long pants. For example, in the mixing/loading for aerial applications study ( MRID 447393 02) , participants

wore chemical

- resistant glo ves, apron and knee high boots. In another study, mixing/loading/applying for ornamentals in greenhouses, the workers wore c hemical

- resistant gloves, socks, rubber boots, and protective eyewear. In this same study, participants who conducted overhead app lications also wore neoprene rain paints and a rai n jacket over the coveralls, a half face respirator equipped with two organic vapour cartridges and pre

- filters, and

a fac e shield. The study authors attempted to account for the additional PPE through mea ns of assigned penetration factors. It is possible that the additional PPE, despite correction, affect passive and biomonitoring results by reducing worker exposure to chlorpyrifos that would have otherwise deposited on the inner or outer dosimeters in th eir absence and likewise, result in an assessment which potentially underestimates human health exposure/risk for the exposure scenario. This is of particular concern in the greenhouse study because the personal protective equipment worn by study participa nts making overhead applications exceeds current labelled requirements.

Because the 4 available studies were conducted with study participants wearing a specific combination of clothing and PPE, the utility of the data are limited to assessment of occupa tional handler exposure/risk which is represented by that level of clothing or personal protection. For example, in the mixing/loading for airblast application study ( MRID 431381 02) workers wore inner dosimeters (t

- shirts and briefs), short sleeved shirt, long pants and outer dosimeters (coveralls), chemical resistant gloves and half

- face respirator. Therefore, data from the study would be limited to the assessment of occupational handlers mixing/loading liquids with double layer clothing, gloves and PF10 respirator. Furthermore, since the available exposure studies are specific to particular handler activities and formulations (e.g., mixing/loading for liquid formulations) the utility of the data are limited to these parameters.

In lieu of the issues o utlined, HED has determined that of the 4 available studies reviewed, 3 should be considered for quantitative risk assessment purposes ( MRIDs 429745 01, 431381 02,

and MRI D 447393 02). The mixing /loading liquid s for aerial applications study ( MRID

447393 02) was used to present a comparative biomonitoring estimate for the mixing/loading liquids for aerial applications exposure scenario at double layer clothing, gloves and no respirator level of personal protection. The mixing/loading liquids for and airblast application study ( MRID 431381 02 ) was used to present a comparative estimate for the mixing/loading liquids for airblast application and airblast application exposure scenario at single layer clothing, gloves and PF10 respirator level of personal protectio n. Study MRID 429745 01 measured exposure from the mixing/loading and application of a wettable powder formulation and mixing/loading of a liquid formulation for ground boom application. Because the wettable powder formulation is noPage 44 of 107

longer supported, only the subsequent liquid application by ground boom exposure data was used to present a comparative estimate at single layer, gloves and PF10 respirator level of personal protection. A summary of all studies considered is presented in Section 2.2.2: Occupat ional Handler Chemical Specific Data.

2. 2.1 Occupational Handler Biomonitoring Exposure and Risk Calculations

Chlorpyrifos occupational handler biomonitoring exposure and risk M OE estimates were calculated using measures of absorbed dose as calculated from the urinary metabolic measures

from the 3 available studies. Pre

- and post

- exposure urine measurements were conducted in the

studies and measured for 3,5,6

- trichioropyridinol (TCP), the primary urinary metabolite of chlorpyrifos . Measures of TCP in all studies were corrected for background (pre

- exposure) concentrations of TCP and the completeness of daily urinary collection.

Although study participants were instructed to av oid exposure to chlorpyrifos prior to the studies, measureable quantities of TCP were commonly found in pre

- study urine specimens. The pre

exposure urine levels were considered to represent background and the participants were

assumed to have had some unkn own steady state exposure to chlorpyrifos. The daily measured

TCP levels were therefor e, each corrected for the TCP residues detected in the sample from the measured interval prior to the exposure event. In addition, the completeness of urine collection was determined in all studies by analyzing urine samples for creatinine content. The creatinine concentration and urine volumes were used to determine total daily creatinine output. The results were compared to and corrected based on to an average daily creatinine excretion rate of 1.8 g/day (95% range of 1.1 to 2.5 g/day) based on standard literature values ( Documenta Geigy,

1970 ).

Total chlorpyrifos (μg) absorbed after exposure in the studies was calculated using two methods. In both methods, TCP w as corrected for background chlorpyrifos exposure and incomplete urine collection. The method resulting in the highest measures of chlorpyrifos absorbed was used to represent total chlorpyrifos for each monitored worker.

In the first method (urinary ex cretion factor method), the am ount of chlorpyrifos absorbed i s estimated by dividing the cumulative amount of TCP excreted in the urine by the urinary excretion factor, 0.370. This factor was based on the kinetics of TCP in human volunteers given single o ral and dermal doses of chlorpyrifos. The urinary excretion f actor corrects for the following : a) only 72% of an oral dose of chlorpyrifos was excreted in the urine as TCP b) the percentage of the urinary TCP expected to be eliminated during the time int erval during which urine was collected, and c) the difference in molecular weights for TCP and chlorpyrifos (i.e., 198 and 350.6).

In the second method (kinetic model method), the amount of chlorpyrifos absorbed i s estimated by fitting the amount of TCP excreted in the individual urine specimens to the one compartment pharmacokinetic model that described the time

- course of TCP in urine of volunteers following application of chlorpyrifos to their forearm (Nolan et al., 1984). Based on Nolan et al. it was assumed that 72% of the absorbed chlorpyrifos would be excreted in the urine as TCP. APage 45 of 107

computer program, “SIMUSOLV*,” was used to perform optimization for the parameters of this

model.

2.2.2 Occupational Handler Chemical Specific Data

MRID

- 429745 01: Shurdut, B.A. et al. 1993. Lorsban® 4E and 50W insecticides: assessment of Chlorpyrifos exposures to applicators, mixer/loaders and reentry personnel during and following application to low crops.

LORSBAN® 4E was applied using boom type sprayers at 2 lb ai/acre to Christmas trees in Michigan and LORSBAN® 50W was applied to cauliflower and tomatoes at 1 lb ai/acre in Arizona and Florida, respectively. A total of 18 workers were monitored in the study (9 mixer/loaders and 9 applicators). Passive dosimetr y and biological monitoring (urine and blood) were conducted to determine potential inhalation and dermal exposure as well as total absorbed dose. Mixer/loaders and applicators wore, as a minimum, t

- shirt, briefs, coveralls, socks and

chemical resistant b oots. In addition, the mixer/loaders wore a half face respirator, gloves and goggles.

Passive dosimetry evaluated by measuring the deposition of chlorpyrifos on coveralls, and the t

shirt and briefs underneath. To accomplish this, cotton coveralls were used as whole body dosimeters to measure the amount of chlorpyrifos deposited on the outer surface of the worker's clothing. In addition, cotton underwear (T

- shirt and briefs) were used as dosimeters to measure chlorpyrifos that penetrated through the ou ter coverall. To assess exposure to the head, a cotton denim patch was attached to a baseball hat. Hand rinses were used to determine the deposition of chlorpyrifos to the surface of the hands.

Biological monitoring was used to evaluate the amount of c hlorpyrifos absorbed. Urine specimens were collected at approximately 12

- hour intervals over a six

- day period and were analyzed for TCP. Blood plasma cholinesterase levels were also monitored in worker exposure volunteers by means of pre

- (baseline) and post

- e xposure blood sampling. Blood plasma ChE

measures resulted in an average increase of baseline to post

- exposure of 1.6 % and ranged from a 14% reduction to a 23 % increase.

Although the dermal exposure data collected for the mixer/loader/applicator p ortion of the chlorpyrifos groundboom treated cauliflower, tomatoes, and Christmas trees do not meet all of the criteria specified in Subdivision U (currently referred to as Series 875 Group A), the data are of sufficient quality to be used for quantitativ e risk assessment purposes. However, results from the wettable powder formulation have not been considered because it is no longer supported. The product is now formulated as a wettable powder in WSP.

The monitoring data from the study are presented i n Table 2.2.2a below for comparison of the passive dosimetry to the absorbed dose.

Table 2.2.2a : Passive and Absorbed Doses (mg/lb ai): Mixing/Loading for and Applying

Wettable Powder Formulation with Groundboom and Mixing/Loading Liquid Formulation (MRID 429745 01 )Page 46 of 107

Table 2.2.2a : Passive and Absorbed Doses (mg/lb ai): Mixing/Loading for and Applying

Wettable Powder Formulation with Groundboom and Mixing/Loading Liquid Formulation (MRID 429745 01 )
Mixer/Loader of the 50W Formulation (No Longer Supported)

Mean ± SD
Amount Handled (lb ai) 33 ± 14 (n = 6)

Biological Monitoring (mg/ kg ) 0.012 ± 0.0069 (n = 6)

Passive Dosimetry

-- Total absorbed (3% dermal and 100% inhalation oral equivalent) dose ( mg/kg) 0.033 ± 0.024 (n = 6)

Mixer/Loader of the 4E Formulation

Mean ± SD
Amount Handled (lb ai) 107 ± 17 (n = 3)

Biological Monitoring ( mg/kg) 0.0 078 ± 0.010 (n = 3)

Passive Dosimetry

-- Total absorbed (3% dermal and 100% inha lation oral equivalent) dose ( mg/kg) 0.0096 ± 0.016 (n = 3)

Applicator

- Groundboom Open Cab

Mean ± SD
Amount Handled (lb ai) 33 ± 14 (n = 6)

Biological Monitoring (mg/kg) 0.0023 ± 0.0014 (n = 6)

Passive Dosimetry

-- Total absorbed (3% dermal and 100% inhalation oral equivalent) dose (mg/kg) 0.0023 ± 0.0012 (n = 6)

MRID

- 431381 02: Honeycutt, R.C. & Day, E.W. Jr. 1994. Evaluation of the Potential Exposure of Workers to Chlorpyrifos During Mixing and Loading, Spray Application, and

Clean

- up Pro cedures During the Treatment of Citrus Groves with Lorsban® 4E Insecticide.

Passive dosimetry (dermal and inhalation) and biological monitoring samples (blood and urine analysis) were collected for 15 open pour liquid mixer/loader monitoring units and 15 open cab airblast applicator monitoring units in Ventura, Kern and Tulare Counties California. The applications were made to citrus groves (i.e., lemons and oranges) using Lorsban® 4E at the maximum label rate of 6 lb ai/acre. Mixer/loader, applicator a nd clean up workers dressed in inner dosimeters (t

- shirts and briefs), short sleeved shirt, long pants and outer dosimeters (hand

made denim coveralls), chemical resistant gloves, boots, goggles and respirator. Workers were monitored for chlorpyrifos expo sure during and after the Lorsban® 4E application. Also, face and neck exposure was monitored using head patch samples. Hand exposure was monitored using hand washing techniques. Respiratory exposure of chlorpyrifos to workers was monitored using person al air monitoring pumps.Page 47 of 107

Biological monitoring was used to evaluate the amount of chlorpyrifos absorbed. Urine specimens were collected at approximately 12

- hour i ntervals over a four

- day period. The samples were analyzed for TCP. Blood cholinesterase levels (plasma and RBC) were also monitored in worker exposure volunteers by means of pre

- (baseline) and post

- exposure blood sampling. Plasma and RBC ChE measures resulted in a reduction of baseline to post

- exposure of 0.98 and 4.2 %, respectively. Blo od plasma ChE levels ranged from a 31% reduction to a 38 % increase. Blood RBC ChE levels ranged from a 31% reduction to a 40 % increase.

The study meets the acceptability criteria outlined in Subdivision U of the Pesticide Assessment Guidelines. The q uality control/quality assurance aspects of the passive dosimetry were adequate for the dermal whole

- body dosim etry and inhalation. The quality control/quality assurance aspects of the biological monitoring were sufficient. The data from this study are of sufficient scientific quality to be used in the assessment.

The monitoring data from the study are presented in Table 2.2.2b below for comparison of the passive dosimetry to the absorbed dose.

Table 2.2.2b : Passive and Absorbed Doses ( mg/ lb ai): Ope n Mixing/Loading and Applying Liquid Formulation for Airblast Application (MRID 431381 02)

Mixer/Loader

- Open Mixing/Loading

Mean ± S D
Amount Handled (lb ai) 78 ± 22 (n = 15)

Biological Monitoring ( mg/kg ) 0. 010 ± 0.021 (n = 15)

Passive Dosimetry

-- Total absorbed (3% dermal and 90% PF for the inhalation for the respirator) dose ( mg/kg ) 0.0062 ± 0.0062 (n = 15)

Applicator

- Open Cab

Mean ± S D
Amount Handled (lb ai) 78 ± 22 (n = 15)

Biological Monitoring ( mg/kg ) 0.013 ± 0.024 (n = 15)

Passi ve Dosimetry

-- Total absorbed (3% dermal and 90% PF for the inhalation for the respirator) dose ( mg/kg ) 0.0059 ± 0.0060 (n = 15)

MRID

- 444835 01: R. F. Bischoff 1998. Evaluation of Chlorpyrifos Exposure to Workers During Loading and Application of Lor sban® 15 % Granular Insecticide During Corn Planting. Passive dosimetry (dermal and inhalation) and biological (urine) monitoring samples were collected for 16 combined monitoring units of loading and applying Lorsban® 15G during corn planting. The test s ubjects loaded the granular product in row planters (8 to 12 row planters) and accompanied the tractor driver (i.e., farmer) in the enclosed cab.

HED is unable to make use of this study as reliance on this study in actions under FIFRA or FFDCA is prohib ited per Kelly Sherman‟s August 26, 2010 memorandum, “Ethics Review of Worker Exposure Study.”Page 48 of 107

MRID 447393 02: Knuteson et. al. 1999. Evaluation of Potential Exposure to Workers Mixing and Loading Lorsban®

- 4E Insecticide Products for Aerial Application.

Exposures were estimated based on both passive dosimetry measurements and biomonitoring of urinary TCP. This study characterizes exposures to 14 workers during the mixing and loading of

Lorsban®

- 4E or Lorsban® 4E

- SG, a 45 percent emulsifiable concentrati on insecticide for aerial application to cotton, alfalfa and wheat. Each worker mixed and loaded enough product to cover a 500 acre per day target rate (170 to 250 lb ai and 42.5 to 62.5 gallons product for wheat and 500 lbs ai and 125 gallons of product for cotton and alfalfa). Lorsban® was applied at the maximum label registered application rates of 0.5 lb active ingredient (ai) per acre for wheat, and 1.0 lb ai per acre for cotton and alfalfa. The study examined exposures to a total of 15 workers,

fiv e for wheat in Dalhart, Texas, five for cotton in Gila Bend, Arizona and five for alfalfa in Gila Bend, Arizona. The mixing/loading exposure period ranged from 40 to 131 minutes, with an average of 89 minutes. The workers wore cotton overalls, a cotton t

- shirt, briefs, and socks, chemical resistant gloves, chemical resistant apron and knee

- high chemical resistant boots, goggles and a hat during the mixing/ loading operation.

A summary of the study results are provided below. The majority of the exposur e data meet the criteria specified in Series 875 Group A. Only minor issues were identified. The study evaluated 15 workers, however one of the workers dropped out of the study the day after exposure and another performed and activity outside of mixing/l oading and, therefore these were

not included in the passive dosimetry or biomonitoring results. The monitoring data from the study are presented in Table 2.2.2c below for comparison of the passive dosimetry to the

absorbed dose.

Table 2.2.2c : Passive and Absorbed Doses (mg/lb ai): Mixing/Loading and Applying Liquid Formulation for Aerial Application (MRID 447393 02)

Mean ± S D
Amount Handled (lb ai) 398 ± 136 (n = 13)

Biological Monitoring ( mg/kg ) 0.0015 ± 0.0014 (n = 13)

Passive Dosimetry

- - Total absorbed (3%

dermal and 100% inhalation oral equivalent) dose ( mg/kg ) 0.00097 ± 0.00052 (n = 13)

. MRID 430279 01: Contardi et. al. 1993. Evaluation of Chlorpyrifos Exposures During Mixing/Loading and Application of EMPIRE 20 Insecticide to O rnamental Plants in Commercial

Greenhouses

This study was designed to examine chlorpyrifos dermal and inhalation exposure to 16 handlers applying EMPIRE 20 ( a flowable microencapsulated formulation of chlorpyrifos) to ornamentals in a greenhouse. The gree nhouse was located in the Columbus, Ohio area and the study was conducted on five different days. Each monitoring unit was responsible for performing all tasks associated with typical application of the test product, including mixing, loading, applicatio n,Page 49 of 107

and clean

- up (in two instances, however, clean

- up activities were not performed). Exposure was estimated based on both passive dosimetry measurements and biomonitoring of urinary TCP

.

Ten of the workers applied EMPIRE 20 to plants on the floor or o n benches and six applied EMPIRE 20 to hanging overhead plants. Mixing/loading activities involved the handler pouring the test product (packaged in 16 oz plastic bottles) directly into the mix tank. The application activities varied, but generally consis ted of the applicator walking down each row while spraying the plants on one side only, usually holding the spray nozzle in one hand and the hose in the other. Application equipment used by the handlers was not clearly specified in the study report.

Usin g best professional judgement in interpretation of application equipment, there were 10 handgun spray equipment handlers, 1 electrostatic sprayer handler, 3 handlers operating backpack/low pressure handwand sprayers and 2 handlers making applications using a fogger sprayer. Following the application, each handler (except workers 7 and 8) performed clean

- up activities which involved flushing the tank mix and hose/nozzle with water and rolling up the

hose.

Each handler wore a clean pair of briefs and T

- sh irt, long

- sleeve cotton coveralls, chemical

resistant nitrile gloves, socks, rubber boots, and protective eyewear. The overhead applicators also wore neoprene rain paints and a rain jacket over the coveralls, a 3M half face respirator equipped with two or ganic vapour cartridges and pre

- filters, and a face shield. One floor/bench worker ( worker 4) also wore neoprene pants and all floor/bench workers wore a baseball cap.

While this study meets many of the criteria specified in Series 875 Group A , there ar e several

issues which limit the utility of the study for quantitative risk assessment purposes. These issues include the following:

Limited Sample

- The principal concern is that the study has been determined to contain

an insufficient number of workers . Applications were conducted with 4 different types of sprayers to three different plant orientations (bench, floor, overhead). Among the 16

workers observed there were:

o 10 handgun spray equipment handlers (5 bench/floor, 5 overhead)

o 1 electrostatic spr ayer handler (1 overhead)

o 3 handlers operating backpack/low pressure handwand sprayers (3 bench/floor)

o 2 handlers making applications using a fogger sprayer (1 bench/floor and 1 overhead application).

Clothing Penetration Factors

- O verhead applicators wore neoprene rain pants and rain jackets over long

- sleeve cotton coveralls, briefs, t

- shirt, gloves socks, rubber boots and a half face respirator. While clothing penetration factors were calculated to determine passive dosimetry despite the addition of coveralls, neoprene pants and jackets, penetration factors calculated for 2 overhead applicators are questionable because the

inner dosimeter t

- shirt/brief and outer dosimeter torso samples were both less than the

limit of detection.

Inhalation PPE

- T he overhead handlers OV respirators that are presumed to provide a 90%Page 50 of 107

protection factor via inhalation. Therefore, the inhalation component of exposure would not have been captured by the biomonitoring of those handlers.

Inner Dosimeters

– For 3 bench /floor workers , the inner dosimeter t

- shirt/brief samples

were less than the detection limit. These workers were used to calculate average penetration factors for each handler type, which were then used to calculate dermal

exposure.

Inhalation Measures

- The inhalation measures reported for single overhead electrostatic

sprayer workers the loading sample was reported as higher than the total in the study report, therefore invalidating results for worker

.

The monitoring data from the study are presente d in Table 2.2.2d below for comparison of the passive dosimetry to the absorbed dose.

Table 2.2.2d : Passive and Absorbed Doses (mg/lb ai): Mixing/Loading and Applying Liquid Formulation for Greenhouse Application (MRID 430279 01 )

Bench/Floor

– Handg un

Mean ± S D
Amount Handled (lb ai) 0.49 ± 0.23 (n = 5)

Biological Monitoring ( mg/kg ) 0.0025 ± 0.000059 (n = 5)

Passive Dosimetry

-- Total absorbed (3% dermal and 100% inhalation oral equivalent) dose ( mg/kg ) 0. 00070 ± 0.00036 (n = 5)

Bench/Floor

– Backpack/Low Pressure Handwand

Mean ± S D
Amount Handled (lb ai) 0.11 ± 0.04 (n = 3)

Biological Monitoring ( mg/kg ) 0.011 ± 0.00010 (n = 3)

Passive Dosimetry

-- Total absorbed (3% dermal and 100% inhalation oral equivalent) dose ( mg/kg ) 0.00014 ± 0.000086 (n = 3)

Bench/Floor

- Fogger

Mean ± S D
Amount Handled (lb ai) 13 (n = 1)

Biological Monitoring ( mg/kg ) 0.25 (n = 1)

Passive Dosimetry

-- Total absorbed (3% dermal and 100% inhalation oral equivalent) dose ( mg/kg ) 0.30 (n = 1)Page 51 of 107

Table 2.2.2d : Passive and Absorbed Doses (mg/lb ai): Mixing/Loading and Applying Liquid Formulation for Greenhouse Application (MRID 430279 01 )

Overhead

- Handgun

Mean ± S D

Amount Handled (lb ai) 0.66 ± 0.29 (n = 5)

Biological Monitoring ( mg/kg ) 0.0019 ± 0.000064 (n = 5)

Passive Dosimetry

-- Total absorbed (3% dermal and 100% inhalation oral equivalent) dose ( mg/kg ) 0.0089 ± 0.0092 (n = 5)

2.2 .2 Occupational Handler Comparison Using Biomonitoring Data Risk Summary

Appendix B, which accompanies this document, present s the comparative short

- and

intermediate

- term occupational handler expos ure/risk estimates . Risk estimates compare the

level of personal protection measured in biomonitoring exposure studies and the corresponding

level estimated using surrogate exposure data. Evaluation of biomonitoring data was conducted based on a comparison of the absorbed dose as measured by urinary excretion of 3,5,6

- trichloro

2

- pyridinol (TCP), to the oral equivalent NOAEL of 0.15 mg/kg/day (i.e., 5 mg/kg/day from 21

- day dermal study x 0.03 dermal absorption) because the majority of exposure is via the dermal

route.

Of the 4 exposure scenarios compared, 3 (mixing/loading liquids for airblast application, airblast applications, and groundboom applications) result in biomonitoring estimates of greater risk potential than those estimated using surrogate data (i.e., the estimated MOEs are lower). The analysis of the exposure scenario, mixing/loading liquids for aerial application, results in reduced risk potential (a 3.8X reduction in MOE estimate). Because a number of issues were identified which limit the utility of the available biomonitoring data, HED has determined that these data are best suited for characterization of the estimates calculated for representative exposure scenarios using the surrogate data.

2.3 Commercial Seed Treatment

Based upon the registered seed treatment use s of chlorpyrifos , occup ational handler exposure is expected for individuals involved in commercial seed treatment. Post

- application exposure to agricultural workers is not expected

.

Occupational handlers may experience short

- and intermediate

- term exposure to chlorpyrifos

whi le performing seed treatment activities in commercial settings. In addition, occupational secondary handlers may experience short

- and intermediate

- term exposure while planting chlorpyrifos

- treated seeds. No chemical

- specific handler exposure data were s ubmitted in support of this use pattern. In order to assess commercial seed treatment and seed planting activities, unit exposure data were taken from HED ExpoSAC Policy 14: SOPs for Seed

Treatment. The amount of active ingredient handled depends on the application rate (lb ai/lbPage 52 of 107

seed) and the pounds of seed treated in a day (or the pounds of seed that can be planted in a day),

all of which vary depending upon the seed type. Values for the amount of seed treated and planted per day were obtained from HED ExpoSAC Policy 15. Short

- and intermediate

- term
commercial seed treatment is presented in Appendix C/Table 1 which accompanies this

document

. Short

- and intermediate

- term secondary handler exposure is presented in Appendix

C/Table 2

.

P otential occupati onal exposure scenarios from the use of chlorpyrifos as a commercial seed

treatment include:

Mixing, loading, applying liquid formulations Bagging treated seed Sewing bags Multiple activities

Typically

, for large

- scale commercial seed treatments, workers perform only those specific individual tasks listed above; however, it is assumed that workers also may perform multiple activities throughout the day. As a result a “multiple activities” scenario (i.e. where one worker performs all seed treatment tasks such as loading/applying, sewing, bagging, cleaning, calibration, repair, forklift driver, etc.) w as addressed.

Planting Treated Seed

P otential occupational exposure scenarios from the use of chlorpyrifos as a commercial seed

treatm ent include: p lanting treated seed (secondary handler)

.

Planting treated seed consists of the farmer purchasing bags of treated seed, placing the seed in the hoppe r and applying seed to fields ( considered a secondary handler exposure scenario )

.

2.3.1 Ass umptions for Commercial Seed Treatment Exposure Scenarios

A series of assumptions and exposure factors served as the basis for completing the occupational risk assessment for commercial seed treatment exposure scenarios. The assumptions and factors

used in the risk calculations include:

Chemical

- specific data for assessing exposure during commercial seed treatment and seed planting were not submitted to the Agency in support of this Section 3 application.

U nit exposures are from ExpoSAC Policy 14: SOPs f or Seed Treatment ( May 1, 2003 )

. Unit exposure values from ExpoSAC Policy 14 are based on data for open mixing/loading/application systems.

HED assumes the maximum application rates allowed by labels in its risk assessments.

The amount of seed treated per day at a commercial facility (lb seed/day):

Beans (Field, Green, Kidney, Lima, Navy, Snap, String, Wax), Corn (Sweet)

–Page 53 of 107 194,000
Cotton (Delinted)

– 160,000

Triticale

– 71,800 Cucumber, Pumpkin

– 5,500

Amount of seed treated or planted per d ay (second ary handler) as based on ExpoSAC Policy No. 15 :

Beans (Lima, Snap), Triticale

– 100 Beans (Navy)

– 45

Cotton

– 18 Corn (Field, Sweet)

– 15

Cucumber

– 5 Pumpkin

- 4

The adverse effects for the short

- and intermediate

- term dermal and inhalation endpoints

a re based on studies where the effects were observed in males and females, therefore the average body weight of an adult handler (i.e., 70 kg) is used to complete the risk

assessment.

A short

- and intermediate

- term occupational risk assessment was complet ed based on the toxicity endpoints identified. The same toxicological endpoint was selected for short

and intermediate

- term dermal chlorpyrifos exposures; therefore risk results for all dermal durations are identical. The same applies to all short

- and intermediate

- term inhalation exposure risk estimates. Long

- term exposure durations are not anticipated based upon the use pattern of chlorpyrifos.

An absorption rate was not used for short

- and intermediate

- term dermal risk as sessment
because the short and intermediate

- term toxicological endpoint is derived from a dermal study

. Because the short

- and intermediate

- term inhalation endpoints are based on an inhalation study, no absorption factor is necessary.

The LOC for occupational dermal expos ure ( def ined as an MOE = 100 ) differs from the LOC for occupation inhalation exposure ( defined as an MOE = 30). An aggregate risk index (ARI) is required to combine or aggregate risk from differing routes of exposure
when the LOCs are not the same. An ARI ≥ 1 is not of concern to HED.

2.3.2 Commercial Seed Treatment Exposure and Risk Calculatio ns

Commercial seed treatment exposure and risk was calculated using the formulas and MOE approach described in Section 2.1.4: Occupational Handler Exposure and Risk Calculations. It should be noted that for commercial seed treatment, the application rat e is presented in units, lbs ai/lb seed and daily amount handled is presented in units, lbs seed/day. All other inputs remain as is described in the previous Section.Page 54 of 107

2.3.3 Commercial Seed Treatment and Exposure Risk Summary

The majority, 61 of 64, oc cupational handler seed treatment exposure scenarios assessed (combined dermal and inhalation) resulted in risk estimates which were not of concern to HED (i.e., an ARI > 1) at some level of personal protection. The remaining 3 exposure scenarios

resulted in an ARI < 1 at all level of personal protection considered and, therefore, are of concern

to HED

. All s eed planter (secondary handler) combined short

- and intermediate

- term dermal and inhalation exposure scenarios assessed resulted in an ARI > 1 at som e level of personal protection and, therefore, are not of concern to HED.

Commercial seed handler combined short

- and intermediate

- term dermal and inhalation exposure

and risk for each exposure scenario is presented in Appendix C/Table 1 which accompanies this

document. Secondary handler c ombined short

- and intermediate

- term dermal and inhalation

exposure and risk is presented in Appendix C/Table 2 which accompanies this document.

2.3.4 Commercial Seed Treatment and Exposure Risk Characterization

HED is currently in the process of revising ExpoSAC Policy No. 15: Amount of Seed Treated or Planted per Day ( March 2, 2004 ) in efforts to update the daily amount of seed treated in

commercial seed treatment facilities. With the increasing demand for hybridiz ed treated seeds, there have been modifications not only in the seed treatment equipment, but in the market shares of new and currently registered pesticide products. HED understands that d ue to the high cost of producing hybrid seeds, direc t seeding is d one in a precise manner which requires lower volumes of seed per acre. However, this does not provide a direct correlation to the amount of seed which

is treated in the commercial seed treatment facilities. Over the past several years, HED has

received s ubmissions from Industry for the use of several seed treatment pesticides which provide a range of daily amounts of vegetable seeds trea ted (1,000 to 5,500 lbs). The amount chosen for cucumber and pumpkin seeds (5,500 lbs) is assumed to be conservative.

2.4 Occupational Post

- application Exposures and Risks

HED uses the term post

- application to describe exposures to individuals that occur as a result of being in an environment that has been previously treated with a pesticide (also referred to as

reentry exposure). HED believes that there are distinct job functions or tasks related to the kinds of activities that occur in previously treated areas. Job requirements (e.g., the kinds of jobs to cultivate a crop), such as the nature of the crop or target th at was treated, and how the chemical residues degrade in the environment can cause exposure levels to differ over time. Each factor

has been considered in this assessment.

2.4.1 Occupational Post

- application Exposure Scenarios

Chlorpyrifos uses are varied as it can be used on agricultural crops and in a variety of other outdoor occupational settings , as well as indoor greenhouses . As a result, a wide array of individuals can potentially be e xposed by working in areas that have been previously treated. HED is concerned about the kinds of exposures one could receive in the workplace.Page 55 of 107

When assessing post

- application exposures to agricultural crops, HED uses a concept known as

the transfer coe fficient (TC) to numerically represent the post

- application exposures an individual would receive (generally presented as cm 2 /hour). The TC concept has been established in the scientific literature and through various exposure monitoring guidelines publis hed by the U.S. EPA and international organizations. The relationship or correlation between field residues and exposure (the statistical and mathematical underpinning of transfer coefficients) was then investigated in the 1980s (USEPA, 1984; USEPA 1998, Popendorf et al, 1980; Popendorf et al, 1982; Zweig et al 1984; Zweig et al 1985 ). Conceptually, a transfer coefficient may be thought of as a „contact factor‟ determining a worker‟s exposure depending on how long they work, what activity they are doing, and how much residue is available for

contact and transfer

. The establishment of TCs also forms the basis of the work of the Agricultural Reentry Task Force. Mathematically, a transfer coefficient is expressed as follows:

The transfer coefficient is essentially a measure of the contact with a treated surface one would have while doing a task or activity. These values are defined by calculating the ratio of an exposure for a given task or activity to the amount of pesticide on leaves, or other surface s, that can rub off on the skin resulting in an exposure. For post

- application exposures, the amounts of pesticide that can rub off on the skin are measured using techniques that specifically determine

the amount of residues on treated leaves or other sur faces (referred to as transferable residues),

rather than the total residues contained both on the surface and absorbed into treated leaves (Iwata, 1977). HED has developed a series of standard TCs that are unique for a variety of job

tasks or activities that are used in lieu of chemical

- and scenario

- specific data.

As is done for occupational handler risk assessment, the first step in the post

- application risk assessment process is to identify the kinds of individuals that are likely to be exposed to

chl orpyrifos after application. Because of U.S. agricultural diversity and in order to do this in a consistent manner, the Agency has adopted a method of clustering crops, crop growth stages, and

post

- application activities into groups that are expected to r esult in comparable exposure. The Agency also considers whether individuals are exposed to pesticides as part of their employment (referred to as occupational risk assessments). Common examples include: agricultural harvesting and scouting activities, cr op maintenance tasks such as irrigating and weeding, and turf maintenances such as mowing. The next step in the risk assessment process is to define how and when chemicals are applied in order to determine the level of transferable residues to which

indivi duals could be exposed over time. Wherever available, use and usage data are included in this process to define values such as application rates and application frequency. HED always completes risk assessments using maximum application rates for each sce nario because what is possible under the label (the legal means of controlling pesticide use) must be evaluated, for complete stewardship, in order to ensure HED has no concern for the specific use. Additionally, whenever HED has additional information, s uch as typical or average application rates or frequency data, it uses the information to further evaluate the overall risks associated with the

use of the chemical. In order to define the amount of transferable residues to which individualsPage 56 of 107

can be expose d, HED relies on chemical

- and crop

- specific studies as described in HED guidelines for exposure data collection ( Series 875, Occupational and Residential Exposure Test Guidelines: Group B

- Post

- application Exposure Monitoring Test Guidelines ). HED has a lso developed a standard modeling approach that can also be used to predict transferable residues

over time in lieu of chemical

- and scenario

- specific data (best described in HED‟s SOPs for Residential Exposure Assessment ). All occupational post

- applicati on exposure scenarios were evaluated using chlorpyrifos

- specific DFR dissipation data.

Next, assessors must understand how exposures to chlorpyrifos occur (i.e., frequency and duration) and how the patterns of these occurrences can alter the effects of th e chemical in the population after being exposed (referred to as dose response). This is supported by the fact that several areas within a work environment may be treated at different times. For example, parts of agricultural fields might be treated over several weeks, because the projected harvest date is different for the different fields. Therefore, individuals working in those fields or exposed to might be exposed from contact with treated areas over an extended period of time that could be categorize d as an intermediate

- term exposure. In these situat ions, typically both short

- term
intermediate

- term dermal exposures and risks are considered. Long

- term post

- application exposure durations to chlorpyrifos are not anticipated

.

B ased on the Agency's curr ent practices, a quantitative post

- application inhalation exposure assessment is not typically performed for a chemical when it is characterized by low acute inhalation toxicity (Toxicity Category III and IV) and low vapor pressure. Chlorpyrifos does not fit into these categories as it is classified as Toxicity Category II for inhalation toxicity and has a

moderate vapor pressure of 1.9 x 10 - 5 mm Hg at 25o C. The inhalation exposure potential from occupational/commercial post

- application activities may b e elevated based upon these criteria. A quantitative occupational post

- application inhalation exposure assessment was not performed for chlorpyrifos; however, an inhalation exposure assessment was performed for occupational/commercial handlers. It is exp ected that while many of these handler inhalation exposure estimates are of concern to HED, exposure and risk from occupational post

- application inhalation would be of no greater concern than occupational handler inhalation estimates.

The use of persona l protective equipment or other types of equipment to reduce exposures for

post

- application workers is not considered a viable exposure/risk mitigation strategy for the regulatory process. This is described in some detail in EPA‟s Worker Protection Standa rd (40CFR170). As such, an administrative approach is used by HED to reduce the risks and is

referred to as the Restricted Entry Interval or REI. The REI is the time period follow a pesticide application during which entry into the treated area is restri cted. REIs from p ost

- application risk levels are generally calculated in the risk assessment process on a chemical

- , crop

- , and activity

specific basis . To establish REIs, post

- application risks are considered on varying days after an application. REIs for chlorpyrifos uses are currently based upon the most recent assessment of

post

- application exposure conducted in June 2000 (T. Leighton, D63893), “ Agricultural and Occupational Exposure Assessment and Recommendations for the Reregistration Eligibility

D ecision Document for Chlorpyrifos.” HED has used the basic approach described above since the mid 1980s for calculating post

- application risks to pesticides. From that time to the present, several revisions and modifications were made to HED policies as data which warranted such changes became available. In 1995, HED issued a Data Call

- In for post

- application agriculturalPage 57 of 107

data that prompted the formation of the Agricultural Reentry Task Force (ARTF). In 2001 the ARTF submitted final reports on 27 worker reentry exposure studies, numerous studies in support of the surrogate compounds used in the reentry studies (method validation, field stability, storage stability, etc.) and a report on its comprehensive survey of growers ( www.exposuretf.com )

. As a result of the need for the revision and using the latest data, HED developed a revised policy entitled the Science Advisory Council for Exposure (ExpoSAC) Policy Number 3.2: Agricultural Transfer Coefficients ( 5/5/11 ). The revision to this policy entailed linking worker activities to more specific crop/agronomic groupings and making better use of the available occupational post

- application exposure data. HED used the updated policy to develop scenarios for occupational post

- application exposures. Chlorpyrifos uses were identified in the following crop groupings from the policy:

Low Berry (e.g., strawberry, cranberry); Field/row crops, low/medium (e.g., alfalfa, clover, soybean); Field/row crops, tall (e.g., c orn, sorghum, sunflowers); Trees/fruit, deciduous (e.g., apples, pears); Trees/fruit, evergreen (e.g., Christmas trees, citrus); Trees/nut (e.g., almonds, filberts, pecans, walnuts); Turf/sod (e.g., golf courses, sod farms);

Ornamentals/nurs eries (e.g., conifers, non

- bearing trees, ornamentals); Vegetable/root (e.g., carrot and radish (grown for seed)); Vegetable/fruiting (e.g., pepper ); Vegetable/head and stem brassica (e.g., broccoli, cabbage, cauliflower); Vegetables/leafy (e.g., b ok choy, collard greens, kale, kohlrabi); Vegetables/stem and stalk (e.g., asparagus); Vine/trellis (e.g., grapes); and Nursery crops (e.g., bedding plants, woody ornamentals, potted flowers.)

Within each agronomic group, a variety of cultu ral practices are required to maintain the included crops. These practices are varied and typically involve light to heavy contact with immature plants as well as with more mature plants. HED selected transfer coefficient values in its revision of Policy 3.2 to represent this range of exposures within each agronomic group.

2.4.2 Data/Assumptions for Post

- application Exposure Scenarios

A series of assumptions and exposure factors se rved as the basis for completing the occupational

post

- application worker risk assessments for agricultural scenarios. Each assumption and factor is detailed below on an individual basis. In addition to these values, transfer coefficient values

were used to calculate risk estimates. Several chemical

- specific residue dissipation studies were were used in the development of the risk estimates. The transfer coefficients were taken from HED‟s revised policy entitled the Science Advisory Council for Exposure (ExpoSAC) Policy Number 3.2: Agricultural Transfer Coefficients. The assumptions and factors used in the risk calculations are presented below:

There are many factors that are common to handler and post

- application risk assessmentsPage 58 of 107

such as body weights, duration, and ranges of application rates. Please refer to the assumptions and factors in Section 2.1.1: Assumptions for Handler Exposure Scenarios for further information concerning these values which are common to both handler and

post

- application risk assessments. In the post

- application risk assessment, generally only maximum application rates were considered because of the complexity of the

calculations.

A total uncertainty factor of 100X was applied to the endpoint selected for short

- and

intermed iate

- term dermal exposure s [ 10X for interspecies extrapolation, 10X for intraspecies variation and a 1X FQPA factor (residential)].

The available dislodgeable foliar residue (DFR) and turf transferable residue (TTR) data for chlorpyrifos were used to comp lete all post

- application risk assessments involving agricultural crops and turf grass. The chemical

- specific residue data are described in

detail below in Section 2.4.2.1

.

Exposure calculations reflect chemical

- specific residue dissipation rates over t ime coupled with surrogate transfer coefficients as outlined in HED‟s revised policy. Chlorpyrifos is used on numer ous agriculture crops but only 7 residue studies were submitted that meet current HED guidelines for sampling techniques and data quality.

A pseudo

- first order kinetics analysis was used to analyze chlorpyrifos residue dissipation over time as outlined in EPA‟s draft Series 875 Post

- application Exposure Monitoring Guidelines

. A more sophisticated curve

- fitting approach is not warranted

beca use any possible refinements associated with such an approach would be inappropriate to apply broadly to all crops and associated activities.

When extrapolating the available DFR data to other crops, HED adjusted (normalized)

the data for differences in application rate using a simple proportional approach. This approach seems to be the most appropriate given the data which are available and is commonly practiced in HED post

- application risk assessments.

Occupational post

- application exposure were calcu lated assuming a central tendency workday duration estimate of 8 hours per day as reviewed by the FIFRA SAP in 2008.

Commercial Seed Treatment

The potential for post

- application exposures following the planting of chlorpyrifos

- treated seeds is unlikely because s ustained levels of contact with treated seed after it has been placed in the soil or other planting media would not be expected because no routine cultural practice required for the production of agricultural commodities involves such an activity as defined in the

“ no/low contact ” criteria in the Worker Protection Standard (WPS)

. Therefore, no quantitative

post

- application assessment is required for exposure to treated seeds that have already been planted

.Page 59 of 107

Occupational Post

- application Inhalatio n

There are multiple potential sources of post

- application inhalation exposure to individuals performing post

- application activities in previously treated fields. These potential sources include volatilization of pesticides and resuspension of dusts and/ or particulates that contain pesticides. The Agency sought expert advice and input on issues related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and receive d the SAP‟s final report on March 2, 2010 ( http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html ). The Agency is in the process of evaluating the SAP report as well as available post

- application inhalation exposure data generated by the Agricult ural Reentry Task Force and may, as appropriate, develop policies and procedures, to identify the need for and, subsequently, the way to incorporate occupational

post

- application inhalation exposure into the Agency's risk assessments.

However, b ased on the Agency's current practices, a quantitative post

- application inhalation exposure assessment is not typically performed for a chemical when it is characterized by low acute inhalation toxicity (Toxicity Category III and IV) and low vapor pressure. Chlor pyrifos does not fit into these categories as it is classified as Toxicity Category II for inhalation toxicity

and has a moderate vapor pressure of 1.9 x 10 - 5 mm Hg at 25o C. The inhalation exposure potential from occupational/commercial post

- application activities may be elevated based upon

these criteria. A quantitative occupational post

- application inhalation exposure assessment was not performed for chlorpyrifos; however, an inhalation exposure assessment was performed for occupational/commercial han dlers. It is expected that while many of these handler inhalation exposure estimates are of concern to HED, exposure and risk from occupational post

- application inhalation would be of no greater concern than occupational handler inhalation estimates.

C hlorpyrifos can be used in indoor facilities as well as agricultural/commercial outdoor uses. Indoor use sites for chlorpyrifos include greenhouse use, indoor commercial uses (e.g., warehouses, indoor industrial sites) and commercial seed treatment facili ties. HED has not assessed post

- application inhalation exposure for greenhouses due to requirements for high air exchange rates and ventilation regulations. The Worker Protection Standard for Agricultural Pesticides contains requirements for protecting w orkers from inhalation exposures during and after greenhouse applications through the use of ventilation requirements [40 CFR 170.110, (3) (Restrictions associated with pesticide applications)]

. Furthermore, HED assumes that commercial applicators do not typically return to the treated areas after an indoor use site pesticide application and thus an occupational post

- application inhalation exposure assessment was not performed for commercial applicators. Seed treatment assessments provide quantitative

inh alation exposure assessments for seed treaters and secondary handlers (i.e. planters). It is expected that these exposure estimates would be protective of most post

- application inhalation exposure scenarios

2.4 .2.1 Post

- application Exposure Study Summaries

The registrant submitted 7 chemical

- specific dislodgeable foliar residue (DFR) studies in support

of the re

- registration of chlorpyrifos. The studies encompass the use of 5 different formulations

and 12 different crops. Specifically, the DFR studies examine the use of 1) emulsifiablePage 60 of 107

concentrate formulations on sugarbeets, pecans, citrus, sweet corn, cotton, and turf; 2) wettable powder formulations on almonds, apples, pecans, caulifl ower, tomato and turf; 3) granular formulations on sweet corn and turf; 4) a total release aerosol formulation on ornamentals; and 5) a microencapsulated formulation on ornamentals. The submitted studies were reviewed by HED. Despite limitations (see su mmary of all DFR and TTR studies in Appendix D which accompanies this document ), HED recommended the use of all or some of the data in the studies

to assess post

- ap plication risks to chlorpyrifos except for the tomato DFR data . More

information on the ava ilable DFR studies is summarized below.

For eac h DFR data set, the raw data are corrected for field and laboratory fortification recoveries

as appropr iate. The data are then log

- transformed. A semi

- log regression analysis is performed on the log

- transf

ormed DRF data ( i.e., log

e DFR vs time) using individual residue data (unless only averages are available) collected from the first interval after the last application through either the last day of sampling or out to the first sampling interval where all or the majority of the

residues are below the level of quantification ( LOQ ) . Residues which are <LOQ are assigned a value of 1⁄2 LOQ for calculation purposes. From the regression analysis, a dissipation rate (slope) and predicted dislodgeable foliar residu e data for each site and crop is determined. For most trials, the actual DFR values were significantly higher than the predicted DFR values in the first sampling intervals after the application. In these cases using the predicted values in the risk

asses sment would underestimate exposure. Therefore, in the risk assessment, the predicted DFR value was replaced with the actual DFR value in the risk calculations

.

MRID 42974501 (Cauliflower and T omato)

This DFR study (MRID 42974501 ), performed in conjuncti on with a passive dosimetry and biomonitoring study, examined the residues of chlorpyrifos on cauliflower and tomato. Three

test sites were established in Arizona for the cauliflower trials and three tests sites were

established in Florida for the tomato trials. Each test plot received a single application of

Lorsban® 50W (a wettable po wder formulation) using tractor

- mounted spray equipment at a
nominal rate of 1 lb ai/A. Samples were taken from the control plot and treated plots using a

Birkenstrand le af punch (producing leaf discs approximately 2.5 cm 2 in area) at the following nominal sampling intervals: the day prior to application, following the application, and at day 1, 2, 3, 5, 7, 14, 21, and 30 after the application. A total of 50 leaf discs we re collected for each sample, totalling 250 cm 2 (front and back of 2.5 cm 2 singe puch x 50 leaf punches). The residues found within a given plot at a given time interval was the average of 3 samples collected within that plot. Samples were analyzed for r esidues of chlorpyrifos. A validated LOQ or LOD was not provided. Concurrent and method validation samples were analyzed. The average recoveries were 110±15.4% and 104±10.3%, respectively. The study corrected the field study samples for

method validati on recoveries, only if the recoveries were <100%. Field fortification data for the tomato sites were extremely variable, with a range of 12.7% to 990%. The study report suggests that either unknown interferences or poor techniques were responsible for th e variability. For cauliflower, the overall average recovery was 99.2%. The field study samples were not corrected for field fortification recovery.

The DFR values for cauliflower and tomatoes were reported as an average of three samples.

Raw data wa s not provided. The DFR data for tomatoes were not used in the assessment due to uncertainty in the results based on the extremely variable field fortification recoveries and alsoPage 61 of 107

because data from two of the sites were erratic. The three cauliflower site s were located in

Arizona and have similar dissipation rates, therefore average daily DFR values were combined for the three sites and the regression was performed on the combined DFR values. A summary of the actual and predicted DFR values can be found in Appendix D/Tables 1 and 2 (which accompany this document) , respectively. The result of statistical analysis for the individual and

combined cauliflower DFR data from the 3 Arizona sites after groundboom application is presented in Table 2.4.2.2a below.

Table 2.4.2.2 a . Cauliflower DFR Dissipation Data After Groundboom Application (MRID 42974501)

Lorsban® 50W (Wettable Powder)

AZ

- Site ABC AZ

- Site DEF AZ

- Site GHI AZ

– All Sites

r 2 0.99 0.93 0.93 0.93

S lope (Ln DFR vs. t)

- 0.19

- 0.198

- 0.23

- 0. 21

T 1/2 (days) 3.59 3.49 2.98 3.33

Notes : The nominal application rate was 1 lb ai/A.

MRID 43062701 (Citrus)

This DFR study (MRID 43062701), performed in conjunction with a worker exposure and biomonitoring study, examined the residues of chlorpyrifo s on citrus. Three test sites were established in California (Site No. 2 and 5 in Tulare County and Site No. 6 in Kern County).

Lorsban® 4E Insecticide (an emulsifiable concentrate formulation), was applied using an airblast spray application to citrus t rees. One application was made at each test site at a nominal rate of 6

lb ai/A. At each sampling interval

, duplicate samples were taken from the control plots and duplicate samples from three subplots were taken from the treated plots using a Birkenstran d leaf punch. Leaf samples were collected prior to and following the application and at 1, 4, 5, 7, 14, 21, 35

, and 43 days after the application for Site No. 2, prior to and following the application and at 1, 2, 7, 14, and 40 days after the application for Site No. 5 and prior to and following the application and at 1, 2, 7, 14, 21, and 35 days after the application for Site No. 6. Samples were analyzed for residues of chlorpyrifos. The overall average concurrent recovery for Site No. 2 was

101% ± 17.2% with recoveries ranging from 67.8% to 126% (n=26). The overall average concurrent recovery for Site No. 5 and No. 6 was 91.8% ± 10.1% with recoveries ranging from 76.6% to 112% (n=29). A validated LOQ was not provided. The limit of detection (LOD) was

set at approximately three (3) times the signal noise ratio for an analytical run. The LOD ranged

from 0.0032 to 0.016 μg/cm 2

. The field study samples did not require correction for field fortification recovery. Average field fortification recoveries were g reater than 100% for Site No.

5 and No. 6. Field fortification data from Site No. 2 indicated that the spiking solutions had degraded causing erratic data for field fortification recoveries, therefore, these recoveries were

not used to correct the raw res idue data and Site No. 5 and Site No. 6 field fortification recoveries were applied to Site No. 2 DFRs.

Actual average DFR values are provided in Appendix D/Table 3 which accompanies this

document

. The chlorpyrifos residues on leaves demonstrated a bi phasic pattern of dissipation. Residue levels dropped dramatically in the first two days, and then dissipation of chlorpyrifos was gradual.Page 62 of 107

Because all the sampling sites are located in California, the average DFR values for each day at

each site were used to plot a regression for all the sites combined. Predicted DFR values calculated from the regression of the individual and combined sites are presented in Appendix

D /Table 4. The result of statistical analysis for the individual and combined citrus DFR data

from the 3 California sites after airblast application is presented in Table 2.4.2.2b below.

Table 2.4 .2.2 b . Citrus DFR Dissipation After Airblast Application (MRID 43062701)

Lorsban® 4EC (Emulsifiable Concentrate)

CA

- Site No. 2 CA

- Site No. 5 CA

- Site No. 6 Combined CA Sites 2, 5,

& 6

r 2 0.58 0.55 0.61 0.67
Slope (Ln DFR vs. t) - 0.13

- 0.14

- 0.15

- 0.15

T 1/2 (days) 5.27 4.83 4.56 4.76

Notes: The nominal application rate was 6 lb ai/A.

MRID 44748101 (Apples, Almonds, Pecans)

This DFR study (MRID 44748101) examined the residues of chlorpyrifos on apple, almond, and pecan trees. Three test sites were established for each crop in the major crop production areas (1 apple trial each in CA, NY and WA; 3 almond trials in CA; 1 pecan tria l each in GA, LA and TX). One treatment plot for the application of Lorsban® 50W (wettable powder) was established at all trial sites. For pecans, an additional treatment plot was established for application of Lorsban® 4E (emulsifiable concentrate). The test products were applied as two airblast spray applications, each at a nominal rate of 1.5 lb ai/A for apple trees and at 2.0 lb ai/A for almond and pecan trees. The re

- treatment intervals were 7 days for apple trees, 15 days for almond trees, and 7 da ys for pecan trees. Applications were made in a spray volume rate of approximately 89

- 109 gallons per acre. At each sampling interval a sample was taken from the control plot and triplicate samples were taken from the treated plot using a Birkenstrand le af punch. Leaf samples were collected at nominal sampling intervals of prior to each application, at days 0, 2, and 5 days after the first application, and at 0, 1, 2, 4, 7, 14, 21, 28 and 35 days after the second application. Samples were analyzed for r esidues of chlorpyrifos. Concurrent recoveries fell within the acceptable range of 70

- 120 percent. The LOD and LOQ were reported as 0.001 μg/cm 2 and 0.003 μg/cm 2 respectively. The overall average recoveries of field fortified samples for apple, almond, and pecan leaves ranged from 73 to 77 percent for the 5 μg/sample level and from 79 to 87 percent for the 50 μg/sample level. DFR values were calculated by adjusting the residues for site

- specific field fortification recoveries when the

recoveries were l ess than 90%. The adjustment was made using the average recovery for the

fortification level closest to the residue level.

Actual average DF R values are provided in Appendix D/ Table 5 which accompanies this

document . Two of the almond sites (CA2 and CA3) were located in California and have similar dissipation rates. Therefore, average daily DFR values were combined for those two sites andPage 63 of 107

the regression was performed on the combined DFR values. The remaining almond site (CA4)

was also located in Cal ifornia, but had much slower rate of dissipation from the other two almond sites. Since this may be reflect of different climatological conditions (i.e., more arid climate), the DFR values from this site were not combined with the other two almond sites. The predicted values calculated from the reg ressions are provided in Appendix D/Table 6. The result of statistical analysis for the individual apple and pecan crop sites and the individual and

combined citrus DFR data from the 3 California sites after ai rblast application is presented in

Table 2.4.2.2c below.

Table 2.4 .2.2 c . A pple, Almond and Pecan DFR Dissipation After Airblast Application (44748101)

Lorsban® WP (Wettable Powder) Lorsban® 4EC (Emulsifiable Concentrate)
Apple Almonds Pecans Pecans

CA NY WA CA2 & CA3 CA4 GA LA TX GA LA TX

r 2 0.77 0.93 0.80 0.82 0.6047 0.99 0.80 0.97 0.65 0.80 0.95
Slope (Ln DFR vs. t) - 0.31

- 0.61

- 0.52

- 0.33 - 0.0873 - 0.37

- 0.25

- 1.70

- 0.96

- 0.24

- 0.61

T 1/2 (days) 2.22 1.13 1.35 2.09 7.94 1.87 2.78 0.41 0.72 2.93 2.25

Notes: The nominal application rate was 1.5 lb ai/A for apple trees (total of 3 lb ai/A) and 2.0 lb ai/A for almond and pecan trees (total of 4 lb ai/A).

MRID 447481 02 (Cotton, S ugarbeet, Sweet C orn)

This DFR study (MRID 44748102) examined the res idues of chlorpyrifos on cotton, sugar beet, and sweet corn after application of either Lorsban® 4E (emulsifiable concentrate), Lock

- on (emulsifiable concentrate), or Lorsban® 15G (granular). Lorsban® 4E trials were conducted on all crops. Lock

- on trials were conducted on cotton only and Lorsban® 15G trials were conducted on sweet corn only. Three test sites were established for each crop for each formulation tested. Cotton trials were conducted in California, Texas, Mississippi ( Lorsban® 4E only) and Ar izona (Lock

- on only). Sugar beet trials were conducted in California, Oregon, and Minnesota. Sweet corn trials were conducted in Oregon, Minnesota, and Illinois. Each test site received two broadcast foliar applications of a test product spaced five day s apart. The application rate used for Lorsban® 4E on all crops was 1 lb ai/A. Lock

- on was applied to cotton

at 0.5 lb ai/A and Lorsban® 15G was applied to sweet corn at 1 lb ai/A. At each sampling interval a sample was taken from the control plot and t riplicate samples were taken from the treated plot using a Birkenstrand leaf punch. Leaf samples were collected at sampling intervals

of prior to the first application, immediately following the application (within 1

- 2 hours or as soon as the spray had co mpletely dried or dust had settled on the foliage), and at 1, 2, and 4 days after the first application. Leaf punch samples were also collected immediately following the second application and at 1, 2, 4, 7, 14, 21, and 28 days after the second (final) ap plication. Samples were analyzed for residues of chlorpyrifos. Concurrent recoveries fell within the acceptable range of 70

- 120 percent. The LOD and LOQ were reported as 0.001 μg/cm 2 and 0.003 μg/cm 2 respectively. Field fortifications were collected on three sampling events at eachPage 64 of 107

test. Average field fortification recoveries (not corrected for laboratory recovery), ranged from

82% to 117%. DFR values were calculated by adjusting the residues for site

- specific field

fortification recoveries when the recoveries were less than 90%. The adjustment was made using the average recovery for the fortification level closest to the residue level.

Actual average DF R values are provided in Appendix D/Table 7 which accompanies this

document

. P redicted values calculated from the reg ressions are provided in Appendix D/Table

8 . A regression was not conducted for the granular application on sweet corn at the Minnesota site because all DFR values were <LOQ. The result of statistical analysis for the individual

c otton, sugar beet and sweet corn crop sites after ground application is presented in Table

2.4.2.2d below.

Table 2.4 .2.2 d

. Cotton, Sugarbeet and Sweet Corn DFR Dissipation After Ground Application (MRID 44748102)

Cotton Sugar beet Sweet Corn

Lorsban® 4E (Emulsifiable Concentrate) Lock

- On (Emulsifiable

Concentrate) Lorsban® 4E

(Emulsifiable Concentrate) Lorsban® 4E

(Emulsifiable Concentrate) Lorsban® 15G

(Granular)

CA TX MS CA AZ TX CA OR MN IL MN OR IL OR

r 2 0.82 0.69 0.87 0.65 0.767 0.539 0.74 0.36 0.83 0.69 0.83 0.82 0.440 0.645
Slope (Ln

DFR vs. t) - 0.40

- 0.91

- 3.21

- 0.29

- 1.458

- 0.170

- 0.35

- 0.61

- 0.43

- 0.95

- 0.78

- 1.33

- 0.498

- 1.014

T 1/2 (days) 1.73 0.76 0.22 2.36 0.475 4.073 1.97 1.13 1.62 0.73 0.89 0.52 1.392 0.684

Notes: Application rate s were 1.0 lb ai/A for Lorsban® 4E and Lock

- On (total of 2 lb ai/A) and 0.5 lb ia/A for

Lorsban® 15G (total of 1 lb ai/A).

MRID 44829601 (T urf)

This TT R study (MRID 44829601) e xamined the residues of chlorpyrifos on turf after application of Dursban®® Pro ( an emulsifiable concentrate), Dursban®® 50W (wettable powder), Dursban® 2.5G (granular) and Dursban® 1F (flowable granular) . Three test sites were established in California, Indiana, and Mississippi, with one test plot for each test substance. Singl e applications of the test products were made to the treatment plots using tractor mounted boom sprayers for the liquid applications and either a tractor mounted air spreader or tractor mounted spreader for the granular applications. The liquid applicatio ns were made at a nominal application ate of 4 lb ai/A and the granular applications were made at a nominal application rate of 2 lb ai/A. Actual application rates, determined by analyzing filter paper anchored to the test plots for liquid applications an d placing plastic pans in the test plots for granular applications, ranged from 95% to 100% for the Dursban® Pro application, 97% to 102% for the Dursban® 50W application, 91% to 95% for the Dursban® 2.5G application and 77% to 86% for the

Dursban® 1F appl ication. Duplicate samples were collected using the California roller technique at the following intervals: one day prior to the application, just after the application (

- 2.5 hours after application), and days 1, 2, 4, and 7 after application. Samples were analyzed for residuesPage 65 of 107

of chlorpyrifos. The overall average concurrent recovery was 98%±3%. The LOD and LOQ were reported as 0.001 μg/cm 2 and 0.003 μg/cm 2 respectively. The field study samples did not require correction for field fortification recovery. A verage field fortification recoveries (corrected for concurrent recovery), at each of three fortification levels were greater than 90% at

all sites.

Actual average TTR values (corrected for concurrent recovery) are provided in Appendix

D/ Table 9 and pred icted values calculated from the regressions are provided in Appendix

D/ Table 10 , both which accompany this document. Regression analysis could not be conducted

for the trials with Dursban® 2.5G because all residues were <LOQ and with Dursban® 1F trials

i n Indiana and Mississippi because there were not enough data points above the LOQ. The result of statistical analysis for the individual turf sites after ground application is presented in Table

2.4.2.2e below.

Table 2.4 .2.2 e

. Turf TT R Dissipation After Ground Application ( 44829601)

Predicted DFR ( μg/cm 2 )

Dursban® Pro (Emulsifiable Concentrate) Dursban® 50W (Wettable Powder) Dursban®

1F ( Granular)

CA IN MS CA IN MS CA

r 2 0.94 0.92 1.00 0.851 0.99 0.98 0.84
Slope (Ln DFR vs. t) - 0.86

- 1.44

- 2.79

- 1.486

- 1.24

- 2.09

- 0.712

T 1/2 (days) 0.81 0.48 0.25 0.467 0.56 0.33 0.97

Notes: Application rates were a nominal 4 lb ai/A for liquid applications ( Dursban® Pro and Dursban® 50W ) and 2.0 lb ai/A for granular applications ( Dursban® 2.5G and Dursban® 1F)

.

MRID 46722701 (Greenhouse Ornamental

- Total Release Aerosol )

This DFR study (MRID 46722701 ) e xamined the residues of chlorpyrifos on smooth leaf (Philadendron) and hairy leaf (African Violet) ornamentals in greenhouses located in Columbia,

Missouri a fter three applications of Duraplex TRTM, a total release aerosol product containing 8.0% chlorpyrifos and 1.6% cyfluthrin. The applications were made at a rate of 2.0 oz formulated product per 1,500 ft 2 (0.008 lb ai/1,000 ft 2 ), using 7 ± 1

- day intervals. The applications were made according to label recommendations by placing a single aerosol canister in the greenhouse and releasing the entire contents at each application. Treated and control leaf punch samples were collected the afternoon of the day pri or to each application, four hours after each application, one day after application numbers 1 and 2, eight hours after the last (third) application, and on days 1, 2, 3, 5, 7, 10, 14, 21, 28, and 35 days after the last (third) application

. Concurrent lab oratory recoveries of smooth leaf samples ranged from 93.3% to 153% with an overall mean recovery of 116% ± 20.4%. Fortification recoveries for hairy leaf samples ranged from 93.9% to 151% with an overall mean recovery of 103% ± 13.5%. The overall mean fie ld fortification recoveries for the smooth leaf and hairy leaf ornamentals were 96% and 87%, respectively. Only the raw residue values for hairy leaf ornamentals required correction for an overall field fortification recovery <90%.Page 66 of 107

Actual average DFR v alues are provided in Appendix D/ Table 11 and predicted values calculated from the regressions are provided in Appendix D/ Table 12 for hairy ornamentals , both which accompany this document. For both plant types, dislodgeable foliar residues increased

init ially (to a maximum on 2 days after the last application for the smooth leaf ornamentals and 8 hours after the last application for the hairy leaf ornamentals) and then declined to a relatively steady state until the end of the monitoring period. The aver age residues on the hairy leaf ornamentals, however, showed a slight increase at the end of the monitoring period. The residues for both plants were very similar, with the hairy ornamental exhibiting slightly higher DFR values. Therefore, only the hairy ornamental DFR data was using for risk assessment

purposes. The result of statistical analysis for the hairy ornamental after total release aerosol application is presented in Table 2.4.2.2f below.

Table 2.4 .2.2 f

. Ornamental (Hairy) DFR Dissipation Afte r Total Release Aerosol Application ( MRID 46722701 )
Duraplex TRTM (Total Release Aerosol)

r 2 0.649
Slope (Ln DFR vs. t) - 0.127

T 1/2 (days) 5.47

Notes: Application rate was a nominal 0.008 lb ai/ 1,000 ft 2

MRID 46722702 (Greenhouse Ornamental

- Micr oencapsulated )

This DFR study (MRID 46722702 ) e xamined the residues of chlorpyrifos on smooth leaf (Philodendron) and hairy leaf ( African Violet) ornamentals in greenhouses located in Columbia, Missouri after three applications of DuraGuard METM insecticid e, a microencapsulated formulation containing 20% (w/w) c hlorpyrifos as the active ingredient . The applications were

made at a rate of 0.5 oz. of DuraGuard METM per gallon of water at a rate of 100 gallons per acre (0.626 lbs ai per acre) , using 14 ± 1

- day intervals. The applications were made using a portable gasoline powered sprayer at a height of approximately 24 inches above the canopy

. Leaf disk samples were collected from the untreated control ornamentals and the treated ornamentals on the following schedule: immediately before each application, immediately after the spray had dried following each application, one day after application number 1 and 2, and on 0.17 (4 hours), 0.33 (8 hours), 1, 2, 3, 5, 7, 10, 14, 21, 28, and 35 days after the third app lication. For smooth leaf ornamentals, laboratory recoveries ranged from 73 to 134% with an overall mean recovery of 97 ± 19%. For hairy leaf ornamentals, laboratory recoveries ranged from 77 to 113% with an overall mean recovery of 92 ± 11%. The initi al set of field fortification samples resulted in poor recoveries (<70%) due to problems associated with the fortification technique. Subsequently, control samples were fortified again and analyzed after 15 and 190 days to assess storage stability. Since only two samples at one concentration were analyzed, it is uncertain if the recoveries obtained from the samples are representative of the field and storage conditions; therefore, the field data were not corrected for the recovery results.

Actual average DFR values are provided in Appendix D/ Table 13 which accompanies this

document

. Chlorpyrifos persisted on both smooth and hairy leaf ornamentals with no rapidPage 67 of 1 07

decline prior to the completion of the monitoring period 35 days following the third application

. A regression analysis was not performed because there was no substantial dissipation of chlorpyrifos residue.

2.4.3 Use of Post

- application DFR Data

HED considered all DFR and TTR data as presented in the above summaries and determined the approaches most appropriate for its use

. DFR data for an individual crop was applied to that specific crop, as well as to crops in the same crop grouping (e.g., cauliflower data was used for cauliflower and all other cole crops). For other crops in which no crop

- s pecific or crop group

specific data are available, the DFR data for the crop deemed the closest match were used as surrogates to calculate potential exposure (e.g., cauliflower data were also used for strawberries, cranberries, and leafy vegetables). Addi tionally, whenever possible, a label use was assessed using DFR data for the same formulation type. Granular, microencapsulated, and aerosol uses were only assessed using DFR data for the same formulation type. For crops with DFR data for

both liquid con centrate s and wettable powder (enclosed in water soluble packets) formulations,

DFR data which resulted in the most conservative risk estimate were used unless one of the formulations was not registered for that crop. For crops where water dispersible gra nule (enclosed in water soluble packets) formulations are registered, DFR data from the liquid concentrates and wettable powder formulations were used as surrogates. If DFR data from multiple within

- State field trial sites for an individual crop were not significantly different, these

were combined. If determined significantly different, the most conservative of the within

- State field trial sites were used for risk analysis (e.g., CA almond DFR study)

.

DFR data from multiple states for the same crop we re kept separate because these were considered to represent unique climatologic regions of the U.S. HED identified growing regions

for chlorpyrifos use site s/crops by referencing the EPA Residue Chemistry Test Guidelines, OPPTS 860.1500, Crop Field Trials (1996) , specifically, “Table 6

– Regional Distribution of Crop Production” and “Attachment 10, Border Definitions of Regions.” HED used a cut point of 10% or greater crop production by region to determine those areas of the US where chlorpyrifos

use is l ikely. Th is regional information was used in conjunction with the multi

- state DFR data to recommend a best fit for the assessment of occupational post

- application exposure and risk. For example, the sweet corn DFR study (MRID 447481 02 ) had trial sites in Illinois, Minnesota and Oregon. This data source was selected as a close match for the assessment of post

- application exposure from chlorpyrifos use on field corn and corn grown from seed. However, field corn and corn grown from seed are grown mostly in Region 5 of the US ( which includes Michigan, Indiana, Illinois, Wisconsin, Minnesota, Iowa and parts of Ohio, West Virginia, Kentucky, Missouri, Kansas, Nebraska, South Dakota and North Dakota). Because the DFR data includes trials from the region, Illin ois and Minnesota, these were recommended and used for assessment purposes, whereas the Oregon data was not identified for use. In the instance that state

- specific DFR data did not result in a regional match, the most climatologically representative data source was selected. Further, if multiple DFR data sources selected for a region result in differing risk estimates, it is recommended that the more conservative of them be selected for the purpose of risk mitigation

. Attachment 10, Border Definitions of Regions has been included in Appendix D (which accompanies this document) for reference. It includes a description of all states and areas within states included for US regional analysis.Page 68 of 107

No formulation

- specific data is available for the assessment of emulsifiable concentrate (EC) greenhouse (nursery) uses of chlorpyrifos. Two DFR studies were submitted to the Agency by the registrant for microencapsulated and total release fogger formulation use in greenhouses.

These studies result in MOE estimates below those estimated using DFR data measured from outdoor chlorpyrifos use and consequently, a significant increase in REIs. Due to the lack of DFR data for the EC formulation in greenhouses, HED has recommended the use of the total release fogger formul ation greenhouse DFR study as a surrogate for all liquid formulation applications. HED determined that the microencapsulated formulation was not appropriate for

use because of its time release characteristic.

The DFR values from the submitted studies w ere adjusted proportionately to reflect the label application rates. The new DFR values are calculated as follows:

The DFR data were extrapolated to the currently labeled crops as follows:

Cauliflower (MRID 42974501):

Berry: Low Vegetable: Head and Stem Brassica Vegetable: Leafy

Citrus (MRID 43062701):

Tree Fruit: Evergreen

Ornamental/Nurseries

Vine/Trellis

Apple (MRID 44748101):

Tree Fruit: Deciduous (Pome and Stone Fruit) Forestry

Ornamentals/Nurseries

Almond and Pecan (MRID 44748101):

Tree Nuts

Cotton ( MRID 447481 02) :

Field and Row Crops: Low to Medium (Fiber, Legume Vegetable, Non

- grass Animal Feeds) Vegetable: FruitingPage 69 of 107

Stalk and Stem Vegetable

Sugarbeet (MRID 447481 02):

Field and Row Crops: Low to Medium

Ornamen tals ( Outdoor Only) Vegetable: Root and Tuber Stalk and Stem Vegetable

Sweet Corn

– Emulsifiable Concentrate and Granular Formulation (MRID 447481 02):

Field and Row Crops: Tall

Turf (MRID 448296 01):

Turf

Greenhouse Ornamentals

– Total Release Aerosol Formulation (MRID 46722701):

Greenhouse Use (All Liquid Formulations)

Greenhouse Ornamentals

– Microencapsulated Formulation ( MRID 46722702 ):

Greenhouse Use (Microencapsulated Formulation Only)

2.4.4 Occupat ional Post

- application Exposure and Risk Sum mary

HED has assessed short

- and intermediate term occupational post

- application dermal exposure and risk for any crops which reentry into an area previously treated with chlorpyrifos is anticipated. The assessment was completed using 7 chemical

- specific registrant submitted DFR studies. The studies, which encompass the use of five different formulations and twelve different crops, have been extrapolated to other groups based on the nature of the crop and application

method and used to calculate risks fo r post

- application workers in every region of the county.

The results of the post

- application exposure and risk assessment are summarized in Table 2.4.4 below. A full presentation of post

- application exposure and risk including estimates calculated

for l ow, medium and high contact activities and resulting REIs reference Appendix E which accompanies this document.

The MOEs estimated for liquid spray and granular formulation reentry are not of concern to

HED (i.e., an M OE ≥ 100) in the range of 0 to 4 days for lower to medium exposure activities

and 0 to 8 days for high exposure activities, with the greater majority falling between 1 to 4 days when all exposure activities are considered. HED also estimated the MOEs for reentry into microencapsulated and to tal release fogger formulation treated greenhouses. These estimates range from 0 to > 35 days after treatment (the completion of the monitoring period) for all exposure activities considered.Page 70 of 107

Table 2.4.4. Occupational Post

- application Exposure and Ris k Summary
Crop Group Crop App. Rate (lbs ai/A) DFR Data

Source DFR

Study Location Growing Region Estimated REI Range (days) (Dermal LOC = 100)
Berry: Low Strawberry 1.0 MRID 42974501 (cauliflower WP) AZ 3, 5, 10 and 12 0

- 2

Cranberry 1.5 1, 5, 1 0 and 12 0

- 4

Field and Row Crops: Low to

Medium Clover (Grown for

Seed) 1.9 MRID 44748102 (sugar beet EC) MN 5 1

OR 11 1

Perennial Grass Seed Crops 1.0 MRID 44748102 (sugar beet EC) MN 5 1

OR 11 1

Alfalfa

1.0 MRID 44748102 (cotton EC) TX 5 and 7 1

Cotton

1.0 MRID 44748102 (cotton EC) CA 10 0

– 3

MS 4 0

– 1

TX 6 and 8 0

– 1 Peppermint/ Spearmint 2.0 MRID 44748102 (sugar beet EC) MN 5 0

– 1

OR 11 0

– 1

Wheat 1.0 MRID 44748102 (sugar beet EC) CA 8 1

MN 5 and 7 1 Soybean 1.0 MRID 44748102 (cotton EC) MS 4 and 5 0

– 1

Sugar Beet

1.0 MRID 44748102 (sugar beet EC) CA 10 0

– 1

MN 5 0

– 1

OR 11 0

– 1

Field and Row Crops: Tall Corn: Sweet

1.5 MRID 44748102 (sweet corn EC) IL 1 and 5 0

– 3

MN 1 and 5 0

– 3

OR 11 0

– 2

Corn: Sweet

1.0 MRID 44748102 (sweet corn EC) IL 1 and 5 0

– 3

MN 1 and 5 0

– 3

OR 11 0

– 2 Corn: Field, Including

Grown for Seed 1.5 MRID 44748102 (sweet corn EC) IL 5 0

– 3

MN 5 0

– 3

Corn: Field, Including

Gro wn for Seed 1.0 MRID 44748102 (sweet corn EC) IL 5 0

– 3

MN 5 0

– 3Page 71 of 107

Table 2.4.4. Occupational Post

- application Exposure and Ris k Summary
Crop Group Crop App. Rate (lbs ai/A) DFR Data

Source DFR

Study Location Growing Region Estimated REI Range (days) (Dermal LOC = 100)
Sorghum

1.0 MRID 44748102 (sweet corn EC) IL 5, 6, 7 and 8 0

– 1

MN 5, 6, 7 and 8 0

– 1

Sunflowers 1.5 MRID 44748102 (sweet corn EC) IL 5 and 7 1

MN 5 and 7 1

Tree Fr uit:

Deciduous Apple

(Dormant and Delayed Dormant) 2.0 MRID 44748101 (apple WP) CA 10 0

– 1

WA 11 0

– 2

NY 1, 2, 5 0

– 2 Cherry (Sweet) (Dormant and Delayed Dormant) 2.0 MRID 44748101 (apple WP) CA 10 0

– 1

WA 11 0

– 2

NY 5 0

– 2 Cherry (Sour) (Dormant and Delayed Dormant) 2.0 MRID 44748101 (apple WP) NY 1 and 5 0

– 2

Peaches (Dormant and Delayed Dormant) 2.0 MRID 44748101 (apple WP) CA 10 0

– 1

NY 2 0

– 2

Pears (Dormant and Delayed Dormant) 2.0 MRID 44748101 (apple WP) CA 10 0

– 1

WA 11 0

– 2

Nectarines, Plums,

Prunes (Dormant and Delayed Dormant) 2.0 MRID 44748101 (apple WP) CA 10 0

– 1

Apples

1.5 MRID 44748101 (apple WP) CA 10 0

– 1

WA 11 0

– 4

NY 1, 2, 5 0

– 4 Cherries (Sour) 1.5 MRID 44748101 (ap ple WP) NY 1 and 5 1

– 4

Peaches (Post

- harvest) 3.0 MRID 44748101 (apple WP) CA 10 0

– 1

NY 2 0

– 2

Pears (Post

- harvest) 2.0 MRID 44748101 (apple WP) CA 10 0

– 1

WA 11 0

– 2

Tree Fruit: Evergreen Conifer Trees and

Christmas Tree 1.0 MRID 43062701 (citrus EC) CA Any 0

– 1Page 72 of 107

Table 2.4.4. Occupational Post

- application Exposure and Ris k Summary
Crop Group Crop App. Rate (lbs ai/A) DFR Data

Source DFR

Study Location Growing Region Estimated REI Range (days) (Dermal LOC = 100)

Plantations

Citrus 6.0 (CA and AZ) MRID 43062701

(citrus EC) CA 3 and 10 0

– 2

3.5 MRID 43062701

(citrus EC) CA 3 and 10 0

– 1

Forestry Cottonwood/ Poplar

Trees Grown for Pulp (Dormant) 2.0 MRID 44748101 (apple WP) W A 11 2

NY 1 and 7 2

Deciduous Trees (Plantations and Seed Orchards) 1.0 MRID 44748101 (apple WP) CA 10 1

WA 11 1

NY 1 and 7 1

Tree Nuts Almonds 2.0 MRID 44748101 (almond WP) CA (arid) 10 1

Almonds (Dormant and Delayed Dormant) 2.0 MRID 44748101 (almond WP) CA (arid) 10 1

Filberts

2.0 MRID 44748101 (pecan EC) GA 12 0

Pecans MRID 44748101 (pecan EC) GA 2 0

LA 6 0

TX 8 0

Walnuts MRID 44748101 (pecan EC) TX 10 0

Filberts (Dormant and Delayed Dormant)

2.0 MRID 44748101 ( pecan EC) GA 12 0

Walnuts (Dormant and Delayed Dormant) MRID 44748101 (pecan EC) TX 10 0

Ornamentals/

Nurseries (Outdoor Only) Deciduous Trees in

Nurseries and Orchards Except Apples (Dormant and 2.0 MRID 44748 101 (apple WP) CA 10 0

WA 11 1

NY 1, 2, 5 1Page 73 of 107

Table 2.4.4. Occupational Post

- application Exposure and Ris k Summary
Crop Group Crop App. Rate (lbs ai/A) DFR Data

Source DFR

Study Location Growing Region Estimated REI Range (days) (Dermal LOC = 100)
Delayed Dormant)

Non

- bearing Apple

Trees

Ornamentals/

Nurseries (Outdoor Only) Non

- bearing Citrus,

Tree Nut and Cherry 4.0 MRID 43062701 (citrus EC) CA 2, 3, 6, 8, 10, 12 0

Non

- bearing Peach

and Nectarine Trees 3.0 MRID 44748101 (apple WP) CA 10 1

NY 2 1

Conifers in Nurseries 1.0 MRID 43062701 (citrus EC) CA Any 0

Field and Row Crops: Low to

Medium (Outdoor Only) Ornamentals 2.0 MRID 44748102 (sugar beet EC) CA Any 0

– 5

MN Any 0

– 6

OR Any 0

– 2

Vegetable: Root

and Tuber Carrot (Grown for

Seed) 0.94 MRID 44748102 (sugar beet EC) CA 10 0

– 1

MN 3 and 5 0

– 1 Radish (Grown for Seed) 0.94 MRID 44748102 (sugar beet EC) MN 3 and 5 0

– 1

Vegetable: Fruiting Pepper 1.0 MRID 44748102 (cotton EC) CA 9 and 10 0

– 2

MS 2 and 3 0

– 1

TX 8 0

– 1

Vegetable:

Head and Stem

Brassica Broccoli, Brussel

Sprout and

Cauliflower 1.0 MRID 42974501 (cauliflower WP) AZ 10

0

– 8 Cabbage MRID 42974501 (cauliflower WP) AZ 1, 2 and 5

Vegetable: Leafy Bok Choy 1.0 MRID 42974501 (c auliflower WP) AZ 3 and 10

0

– 4 Collards, Kale,

Kohlrabi 1.0 MRID 42974501 (cauliflower WP) AZ 2

Stalk and Stem: Vegetable Asparagus

1.0 MRID 44748102 (sugar beet EC) CA 10 0

– 1

MN 5 0

– 1

OR 11 0

– 1

Non

- bearing Pineapple

1.9 MRID 447481 02 (cotton EC) MS 13 0

– 1

Vine/ Trellis Grapes (Dormant and 2.0 MRID 43062701 CA 10 0Page 74 of 107

Table 2.4.4. Occupational Post

- application Exposure and Ris k Summary
Crop Group Crop App. Rate (lbs ai/A) DFR Data

Source DFR

Study Location Growing Region Estimated REI Range (days) (Dermal LOC = 100)
Delayed Dormant)

Grapes (Post

- harvest and Prior to Budbreak) (citrus EC)

Turf Turf for Sod and Seed

4.0 MRID 448296 01 (turf EC and WP) CA 10 1

IN 5 1

MS 2 and 6 1

Turf for Golf Course

1.0 MRID 448296 01 (turf EC and WP) CA 10 0

IN 5 0

MS 2 and 6 0 Granular Applications

Field and Row Crops: Low to

Medium Soybeans 1.0 MRID 44748102 (sweet corn G) IL 4 and 5 0

Sugar Beet 2.0 MRID 44748102 (sweet corn G) IL 5 0

OR 10 and 11 0

– 1

Peanuts 4.0 MRID 44748102 (sweet corn G) IL 2 and 6 0

– 1

Field and Row Crops: Tall Corn: Sweet 1.0 MRID 44748102 (sweet corn G) IL 1 and 5 0

OR 11 0

Corn: Field and

Grown for Seed 1.0 MRID 44748102 (sweet corn G) IL 5 0

Nursery Woody Ornamentals

(In Container and Field Grown) 6.0 MRID 44748102 (sweet corn G) IL Any 0 OR

Turf Turf for Sod or Seed

1.0 MRID 448296 01 (turf G and fertilizer) CA Any 0

Golf Course
0

Microencapsulated Formulation Ap plication

Greenhouse (Microencap. Formulations) Commercial

Ornamentals,

Greenhouse Production: Bedding Plants, Cut Flowers, Flowering Hanging Baskets, Potted 1.4 MRID 46722702 (smooth ornamentals ME) MO Any 0 to > 35Page 75 of 107

Table 2.4.4. Occupational Post

- application Exposure and Ris k Summary
Crop Group Crop App. Rate (lbs ai/A) DFR Data

Source DFR

Study Location Growing Region Estimated REI Range (days) (Dermal LOC = 100)
Flowers, Ornamentals,

Trees and Shrubs Total Release Fogger Application

Greenhouse (Total Release Fogger and. Liquid

Concentrate Formulations) Ornamentals 2 MRID 46722701 (hairy ornamentals ME) MO Any 18 to > 30

Commercial Ornamentals,

Greenhouse Production: Bedding Plants, Cut Flowers

, Flowering Hanging Baskets, Potted Flowers, Ornamentals,

Trees and Shrubs 0.01 lb ai/ fogger/ 3,000 sq ft

0.15 lb ai/A MRID 46722701

(hairy ornamentals ME) MO Any 2

– 22Page 76 of 107

2.4.5 Summary of Exposure Data Gaps

No new data gaps have been identified for t he assessment of occupational handler exposure/risk

in addition to those identified in the Registration Eligibility Decision (RED) for chlorpyrifos ( finalized 7/31/06 ; IRED issued 2/2002)

. These data requirements were addressed in a 90

- day

progress report submitted (August 28, 2003) by the technical registrant, Dow AgroSciences. The following data requirements were addressed which pertain to occupational post

- application exposure to chlorpyrifos:

Exposure data for reentry into treated areas with soil inc orporated/directed applications.

In the 2003, 90

- day progress repo rt, Dow requested a waiver because , “reentry into (e.g., corn field) after soil incorporation is not expected to be a source of exposure to chlorpyrifos. Most soil incorporation use refers to the incorporation of chlorpyrifos into the soil under or adjacent to the seed as they are planted. Thus, a soil incorporated application, due to its placement, does not present a route of exposure, either dermal or inhalation. Added to the lack of a route of exposure to the incorporated material, is the lack of reentry activities for a crop immediately after planting and soil incorporation. Based on these two conditions, the physical barrier afforded by the soil covering the application and the lack of reentry associated with a freshly planted field, Dow requested that a waiver of the requirement for soil residue dissipation data and reentry exposure data for reentry into soil incorporated treated areas be granted .” HED has determined that data

are n o longer required for this potential route of exposure.

Use pattern information (i.e., timing of application relative to post

- application activities, greenhouse DFR, and biological monitoring data to develop transfer coefficients for various greenhouse/ nursery activities).

Dislodgeable foliar residue d ata w ere submitted by Dow AgroSciences, Hicks, S. (2005) Dissipation of the Dislodgeable Foliar Residue of Chlorpyrifos After Application of Duraplex TR (EPA Reg. No. 499

- 405) Insecticide to Smooth Leaf an d Hairy Leaf Ornamentals in a

Greenhouse. Project Number: 48796. Unpublished study prepared by Analytical Bio

- Chemistry Labs., Inc. 110 p. (MRID 46722701) and Hicks, S. (2005) Dissipation of the Dislodgeable Foliar Residues of Chlorpyrifos After Applicati on of Duraguard ME (EPA Reg. No. 499

- 367) Insecticide to Smooth Leaf and Hairy Leaf Ornamentals in a Greenhouse . Project Number:

48797. Unpublished study prepared by Analytical Bio

- Chemistry Labs., Inc. 109 p. (MRID 46722702). HED has reviewed these data and determined that the data are acceptable for quantitative use purposes and, therefore, the requirement is satisfied.

Neither the data addressing the timing of application relative to post

- application activities nor the biological monitoring data requi red for chlorpyrifos greenhouse/nursery ornam ental use have been submitted; however, HED has determined that biological monitorin g data are no longer required. In the 2003, 90

- day response DowAgrosciences responded that the “Agricultural Reentry Exposure Taskforce (ARETF) is in the process of developing transfer coefficients for greenhouse activities and has previously developed TCs for nursery activities.” These data have been received and therefore the requirement has been satisfied.Page 77 of 107

2.4.6 Occupation al Post

- application Characterization

The occupational post

- application exposure and risk assessment for chlorpyrifos is based upon an array of calculations completed for 15 different crop groups. These unique crop groupings are defined essentially based on the nature of the crop where a work activity would take place. Within each of these groupings, ranges of transfer coefficients were considered to reflect differences in exposures that would be associated with the variety of cultural practices required to produce the crop/product. Transfer coefficients are used “generically” to allow for estimation of exposure for any pesticide active ingredient using estimates for exposure time and the

concentration of residue the workers will contact that is specific to the pesticide of interest . The Agency has adopted a method of clustering groups, crop growth stages, and post

- application activities into groups that are expected to result in comparable exposure. Estimates of chlorpyrifos post

- application exposure we re completed over subsequent days after application to reflect residue dissipation over time in the environment and to allow for a more informed risk management decision.

The exposure data used in the chlorpyrifos post

- application exposure and risk asse ssment represent the best data and approaches that are currently available. The latest HED transfer coefficients have been used to complete the assessment, as referenced from the Science Advisory Council for Exposure (ExpoSAC) Policy Number 3.2: Agricultu ral Transfer Coefficients ( 5/5/11). Most of the transfer coefficient values in Policy 3.2 are based on the work of the Agricultural Reentry Task Force (ARTF). The choice of post

- application activities studied by the ARTF, as well as the subsequent assign ment of transfer coefficients derived from these

studies to non

- monitored post

- application activities was developed with input from both the

ARTF and HED staff Agency and reviewed by the FIFRA SAP in 2008. It is possible that there

are exposure scenarios not addressed by HED either due to the lack of appropriate exposure data or because the transfer coefficient model is not appropriate or little or no foliar contact is associated with a specific activity. Furthermore, unlike the vast majority of crop

- acti vity combinations listed under the Transfer Coefficient Table in Policy 3.2, s ome common agricultural activities do not follow the standard “foliar

- based” t ransfer coefficient methodology. This should not be interpreted to mean that there is no potential exposure from these activities

but rather that “foliar

- based” transfer coefficients are not applicable to evaluate worker exposure. For example, the crop

- activity combinations of mechanical windrowing, mechanical sweeping and dormant hand pruning for the “nut tree” crop grouping are standard cultural practices; however, do not follow the standard transfer coefficient methodology.

HED completed the assessment of occupational post

- application exposure and risk to chlorpyrifos using 7 chemical

- specific DFR studies submitted by the registrant in support of the

re

- registration of chlorpyrifos. The studies , which encompass the use of five different formulations and twelve different crops , have been extrapolated to other groups based on the nature of the crop and application method and used to calculate risks for post

- application workers in every region of the county

. It is standard practice for the Agency to use the se kinds

of studies in this manner

. I t is possible that the use of the 7 chemical specific DFR studies to represent all crops and regions within the country could lead to results that do not reflect actual use practices and conditions in some parts of the country. Furthermore, the extrapolation of DFR data from one crop may not represent precisely the dissipation of another. For example, DFRPage 78 of 107

data which measured the dissipation of chlorpyrifos from cotton after application of an emulsifiable concentrate were used to represent dissipation of chlorpyrifos from soybeans which like cotton, are classifi ed in the low/mediu m field row crop grouping. HED assume s that residue dissipation monitored in available studies approximate residues from like crops, but the extent that these residues might be an under

- or over

- estimate is unknown. Finally, DFR data f or several crops were conducted in multiple states reflective of the regions of the country where the crops are typically grown and chlorpyrifos is used. HED has presented all state

- specific DFR data for each crop under the assumption that these data accu rately reflect dissipation anticipated in the different regions of the country (e.g., the subtropical Southeastern U.S. and the semi

- arid

climate of the Central Valley of California ). HED has considered available use and usage information in development o f the occupational post

- application assessment and has refined the use of available region

- specific DFR data to those areas of the U.S. where chlorpyrifos usage

occurs.

In summary, the Agency believes that the risk values presented in this post

- applicat ion assessment represent the highest quality results that could be produced given the exposure, use, and toxicology data that are available. R isk managers and other interested parties should consider the quality of individual inputs when interpreting the results and make decisions accordingly. It is difficult to determine where on a distribu tion the values which have been calculated fall because the distributional data for exposure, residue di ssipation and many other parameters are unrefined. The Agency does believe, however, that the risks represent conservative estimates of exposure because maximum application rates are used to define residue levels upon which the risk calculations are based and many maximum application rates exceed

what is assumed to b e typical

. Additionally, risk estimates are thought to be conservative even when measures of central tendency are used because values that would be considered to be in the lower percentile aspect of any input parameter have not been used in the calculatio ns.

3.0 Residen tial Exposures and Risk s

A residential risk assessment for registered homeowner uses was performed in 2000. The risk estimates of concern resulted in an agreement for the registrants to voluntarily cancel all chlorpyrifos homeowner uses, except a granular ant mound use and roach bait in child

- resistant packaging. A phase out was also developed for termite treatment product s (post

- and pre

construction). To date, all homeowner use product registrations have been cancelled, except for

ant and roach bait products. Additionally, residential/recreational uses remain for aerial and ground

- based fogger ULV mosquitocide and for golf course turf applications.

It has been determined there is the potential for post

- application exposure from ent ering areas previously treated with chlorpyrifos . Post

- application exposure is anticipated from from adults playing golf on chlorpyrifos

- treated courses and from the inhalation of airborne chlorpyrifos or

the contact with residues that have deposited on r esidential turf following aerial and ground

based ULV mosquitocide use . HED assumes that golfers are exposed over short

- and

intermediate

- terms of duration, while a short

- term duration only is assumed for dermal and

incidental oral exposure from the mosqu itocide use

. A cute inhalation exposure is assumed from

the aerial and ground

- based mosquitocide use. There is the potential for residential applicator exposure to occur from the handling of the roach bait product; however, exposure is anticipatedPage 79 of 107

to be n egligible. The ant mound use can only be applied professionally. Residential post

application exposure is not anticipated from either the ant mound or roach bait products.

In addition to the assessment of residential post

- application exposure to chlorp yrifos, HED has assessed inhalation exposure resulting from field volatilization of chlorpyrifos. This residential bystander assessment assumes acute and short

- / intermediate

- term durations of exposure. Due to the unique nature of this assessment, it is presented separately in Section 3.3.

3 .1 Residen tial Handler Exposures and Risks

The Agency uses the term “handlers” to describe those individuals who are involved in the pesticide application process. The Agency believes that there are distinct tasks related to applications and that exposures can vary depending on the specifics of each task. Job requirements (e.g., the amount of chemical to be used in an application), the kinds of equipment used, and the target being treated can cause exposure levels to differ in a manner specific to each application event.

Based upon review of all chlorpyrifos registered uses , only the roach bait products can be applied by an applicator in a residential setting; however, exposure/risk from ap plication of the roach bait products was not quantitatively assessed because HED expects handler exposure to be negligible. The roach bait product is designed such that the active ingredient is contained within the bait station, therefore, limiting contac t with the active ingredient in the product.

3 .2 Residential Post

- application Exposures and Risks

The Agency uses the term “post

- application” to describe exposures to individuals that occur as a result of being in an environment that has been previ ous ly treated with a pesticide. C hlorpyrifos

can be used in areas f

requented by the general population including ant mounds, golf courses

, and as an aerial and ground

- based ULV mosquitocide applied by a public agency made in the vicinity of residential areas

. As a result, individuals could be exposed during the treatment (spray drift) or by entering these areas if they have been previously treated. HED has assessed residential post

- application exposure and risk from the golf course and ULV mosquitocide uses

. Additionally, acute inhalation (spray drift) was assessed for the ULV mosquitocide uses. Exposure from residential ant mound treatment (applied by professional only) was not assessed quantitatively because contact with the mound is not anticipated.

3.2.1 Data and Assumptions for Residential Handler Exposure Scenarios

A series of assumptions and exposure factors served as the basis for completing the residential

post

- application risk assessments. The assumptions and factors used in the risk calculat ions, as detailed below, are consistent with current HED policy for completing residential exposure assessments (i.e., Draft SOPs for Residential Exposure Assessment ). In addition to these factors,

HED has used turf transferable residue ( TTR ) data from a c hemical

- specific turf study.

The assumptions and factors used in this assessment include:Page 80 of 107

HED assumes the maximum application rates allowed by labels in its risk assessments ;

t he tiered approach for personal protection using increasing levels of PPE is not used in

residential risk assessments ;

r esidential post

- application assessments are based on the assumption that individuals are wearing shorts, short

- sleeved shirts, socks, and shoes ;

t he adverse effects for the short

- and intermediate

- term dermal and inhalation endpoints are based on studies where the effects were observed in males and females, therefore the average body weight of an adult (i.e., 70 kg) is used to complete the risk assessment ;

3 year old children are expected to weigh 15 kilograms (representing an average weight from years one to six) ;

HED assumes that golfers can be exposed to chlorpyrifos over an extended duration (short

- and intermediate

- term) based on the potential for frequent play, while a brief duration of exposure (short

- t erm) is assumed for exposure from public health mosquitocide due to the intermittent nature of this application

. Inhalation exposure from the mosquitocide use is assumed to be an acute event.

Exposures to adults golfing have been assessed using the late st HED standard operating procedures for assessment of the turf exposure scenario including:

the TTR at Day 0 from the chlorpyrifos

- specific turf transferable residue study (MRID

44829601 ) was used to assess exposure from golfing. The study was conducte d with an emulsifiable concentrate, granular and wettable powder formulation. HED used the emulsifiable concentrate and granular data; howev er, the wettable powder data were not because no wettable powder formulations are currently registered. The study was conducted at 3 state sites, California, Indiana and Mississippi, using the emulsifiable concentrate and wettable powder formulations and the granular formulation in California only. The liquid applications were made at a nominal application r ate of 4 lb ai/A and the granular applications were made at a nominal application rate of 2 lb ai/A. Exposure was estimated by normalizing Day 0 TTR measures from study application rates to the current maximum application rate allowable by the label. Results have been presented using the

multi

- state data as a representation of distinct climatologic regions;

t he dermal transfer coefficients used are those presented in HED‟s Residential Standard Operating Procedures (SOPs; draft 1997);

h igh contact lawn activites: 14,500 cm 2 /hr for adults and 5,200 cm 2 /hr for children

, g olfing: 3,400 cm 2 /hr for adults ;

t he duration of adult exposure on a golf course is assumed to be 4 hours;

C hildren, who are 12 years of age or older, are likely to represent the vast majority of thePage 81 of 107

youth that play golf on a routine basis. Risk assessments for children (i.e., less than 12 years old) are more difficult to complete because of the increased uncertainties associated with extrapolation of adult dermal exposure data, and because of the increased likelihood of other behaviors that might contribute to exposure, such as mouthing contaminated hands or golf balls. Therefore, the risk associated with children in a golfing scenario is based on the surface area to body weight ratio (SA/BW) for male children 5 years of age (i.e., the difference is larger for males compared to female making the value more protective) calculated by using the 95th percentile body surface area and the 50th percentile for body weight. This skewed SA/BW for children was compared to that of the average adult, and found to be approximately 70 percent greater. Based on this parameter alone, the child‟s exposure could be almost twice that of the adult golfer, however, it should be noted that a child is not expected to us e the golf course for the same length of time as an adult. While an adult is likely to play a full round of golf (i.e., 18 holes), which takes approximately 4 hours, a child would probably only spend about 2 hours (i.e., the 75th percentile for time spent playing on grass by children aged 1

- 4 years

and 5

- 11 years) on the course. Thus, the child‟s shorter duration on the golf course offsets the higher SA/BW, and therefore, the child golfer‟s exposure is likely to be similar to that of the adult golfer. [Note: The values used to calculate SW/BW and estimate time spent playing on grass were obtained from the EPA Exposure Factors Handbook (1997)].

ULV Mosquito Control Applications :

In common agricultural aerial application events, the objective is to del iver the chemical in a manner that minimizes spray drift and deposits the material as quickly as possible to the treated surface. Several engineering aspects are focused on achieving these kinds of results including: the use of larger droplets (that fall and deposit faster); the use of a low aircraft release height; and meteorological condition restrictions for application (e.g., avoidance of thermal inversion conditions).

The objectives of wide area treatments for pests with public health implications su ch as mosquitoes are distinctly different from common aerial agricultural applications. Wide area treatments are generally used for mosquito adulticide chemicals where the efficacy of the compound is dependent upon contacting the mosquito in

- flight. As a result, the engineering aspects of mosquito adulticide applications are antithetical to common aerial agricultural applications. In fact, the objective is to maximize the potential for spray drift by increasing the release height, using (in most cases) U ltra Low Volume (ULV) techniques, and using much smaller droplets that are less likely to quickly fall and deposit on surfaces.

HED anticipates the following exposure scenarios from ULV mosquito application in residential settings:

Dermal exposure from r esidues deposited on turf (adult and child) Incidental oral ingestion of residues deposited on lawns from hand

- to

- mouth transfer (child) Inhalation exposure from airborne residue (adult and child)Page 82 of 107

It should be noted that inhalation exposure usually does n ot factor significantly into residential

post

- application risk. However, due to the use of chlorpyrifos aerial and ground ULV mosquito control applications, a risk assessment was performed. The assessment of residential post

application inhalation was co nducted under the assumption that people are present in the

r e sidential setting during the actual ULV a pplication (ground and aerial). Likewise , inhalation is anticipate d to be an acute event. In contrast, dermal and incidental oral exposures from ULV

ap plications (due to the subsequent settling of airborne residues on turf) are anticipated to be

short

- term in duration because the potential for exposure extends beyond the application event.

For these reason s
, residential inhalation estimates from ULV app lication have been presented,

but not aggregated with the other routes of exposure assessed. While the assessment of post

application inhalation from the mosquitocide use has been included under the residential post

application Section, it is likely more accurately characterized as spray drift.

Chemical

- specific data for mosquito uses are not available. Therefore the equations and assumptions for these scenarios were taken from the Draft SOPs for Residential Exposure

Assessment

. The assumptions are pr esented below and the equations in Section 3.2.2. In addition to the use of the Residential SOPs, the unique nature of the mosquito control uses requires additional information to determine the deposition rate of chlorpyrifos (i.e., the amount deposited o n residential turf).

The following information was used to determine the deposition rates for ground

- based foggers and aerial applications and airborne concentration after aerial applications

.

Ground

- based Foggers:

In the study conducted by Moore et a l., [ Downwind Drift and Deposition of Malathion on Human Targets From Ground Ultra

- Low Volume Mosquito Sprays : J.C. Moore, J.C. Dukes, J.R. Clark, J. Malone, C.F. Hallmon, and P.G. Hester; Journal of the American Mosquito Control Association; Vol. 9, No. 2 (June, 1993)] both human exposure and deposition was quantified over 5 separate application events. A 91 percent formulation of malathion was applied in April and May of 1989 in the early evening (a time of day for relative atmospheric stability). A Lec o HD ULV cold aerosol generator (Lowndes Engineering Company, Valdosta Georgia) was used to make each application. The application parameters included a fluid flow rate of 4.3 fluid ounces per minute, a vehicle ground speed of 10 mph, and a nominal applic ation rate of 0.05 lb ai/acre (i.e., equates to a deposition rate of 0.51 μg/cm 2 ). Deposition was monitored at three locations downwind from the treatment area (i.e., 15.2 m, 30.4 m, and 91.2 m). For the events considered in the deposition calculations, “average amounts of malathion deposited on ground level at 15.2, 30.4, and 91.2 m were not significantly different.” The percentage of the application rate reported to have deposited ranged from 1 to 14 percent. The mean deposition

value for all measurem ents was 4.3 percent (n=35, CV=98).

In the study conducted by Tietze et al., [ Mass Recovery of Malathion in Simulated Open Field Mosquito Adulticide Tests : N.S. Tietze, P.G. Hester, and K.R. Shaffer; Archives of Environmental Contamination and Toxicology; 26: 473

- 477 (1994)] only deposition was quantified over 6 separate application events (i.e., one event was not included in depositionPage 83 of 107

calculations “due to negative air stability”). The application parameters were similar to that used by Moore et al . A 9 5 percent formulation of malathion was applied from May to August of 1993. A Leco 1600 ULV cold aerosol generator (Lowndes Engineering Company, Valdosta Georgia) was also used to make each application. The application parameters included a fluid

flow rat e of 4.3 fluid ounces per minute, a vehicle ground speed of 10 mph, and a nominal application rate of 0.057 lb ai/acre (i.e., equates to a deposition rate of 0.58 μg/cm 2 ). Deposition was monitored at four locations downwind from the treatment area (i.e., 5 m, 25 m, 100 m and 500 m). For the events considered in the deposition calculations, “malathion mass deposited differed significantly between the 500 m site and the three closer sites (df = 3; F

- value = 3.42; P<0.05).” The percentage of the application rate reported to have deposited (not including 500 m samples which were much less) ranged up to 5.8 percent. The mean deposition value for all measurements was 3.8 percent.

After considering the data that are available in the Tietze et al. and Moore et al. papers, an off

target deposition rate of 5 percent of the application rate was used by HED to evaluate ground

based ULV applications (i.e., 5 percent of application rate is the deposition rate of which 20 percent is assumed to be available for dislodgi ng). A value slightly higher than the mean values for both studies was selected because of the variability in the data and the limited number of data points. It should be noted that this value is also consistent with the draft modeling assessment for gro und

- ULV approaches completed by S.T. Perry and W.B. Petersen of EPA‟s Office of Research and Development (i.e., within a factor of 5). Perry and Petersen used “the INPUFF Lagrangian puff model” as the basis for their assessment (Petersen and Lavdas, 1986: INPUFF

2.0

- A Multiple Source Gaussian Puff Dispersion Algorithm, User’s Guide , EPA/600/8

- 86/024). Depending on the scenario selected from this document, deposition rates ranged from approximately 2.5 percent deposition 450 m downwind to 15 to 20 percen t deposition immediately adjacent to the treatment zone

.

Aerial Application :

Data similar to that for ground applications discussed above were not available for the aerial deposition. Therefore, in order to calculate deposition from aerial ULV applicati ons, HED used AgDRIFT (V 2.01) which is the model that was developed as a result of the efforts of the Spray Drift Task Force (SDTF) . The SDTF is a coalition of 38 pesticide registrants whose primary objectives were to develop a comprehensive database of off

- target drift information in support of pesticide registrations and an appropriate model system. This model was selected based on the consensus of several experts in the spray drift area because it represents the current state

- of

- the

art. It is import ant to note that no proprietary SDTF data were used in the completion of this assessment. The following inputs were used as the basis of the AgDRIFT calculations:

AgDRIFT Model Tier: 3

Droplet Size Distribution: D v0.1 = 20.58 μm; D v0.5 = 47.79 μm; D v0.9 = 97.95 μm; and <141 μm = 98.44 percent. [Note: The droplet distribution was developed based on the chlorpyrifos ULV mosquito labeling. No proprietary SDTF data were used in the completion of this assessment.]Page 84 of 107

Spray Material: User

- defined option (oil o ption). Inputs include: nonvolatile rate 0. 24 l b per acre, specific gravity 0.92 , spray rate 0.05 gallons/acre, active ingredient application rate (0.01 lb ai/acre), and evaporation rate ( 0 μm 2 /deg C/sec). [No proprietary SDTF physical property data were used in the completion of this assessment. ]

Aircraft: User

- defined option (fixed

- wing option). Inputs include: Air Tractor AT

- 502

, wingspan: 50 ft (semispan 25 ft), t ypical application airspeed: 155 mph, weight: 6,660 pounds, planform area: 300 ft2 , pro peller RPM: 2,20 0, propeller radius: 4.4 feet, engine

vertical distance: 0 feet, and engine forward distance: 15.25 feet. [Note: AT

- 502

- specific inputs were obtained from the AgDRIFT aircraft library.]

Nozzles: User

- defined option. Inputs include numbe r of nozzles: 3 , vertical distance of nozzles from wing: 0 feet, horizontal distance from wing: 0,

- 17.5 (2) feet, and horizontal

distance limit: 76.3 percent.

Meteorology: Inputs were not changed from Tier 3 recommendations of wind speed: 2 mph, wind di rection:

- 90 degrees (perpendicular to flight path), temperature: 86 F, and relative humidity: 9 0 percent.

Control: Inputs were altered from the Tier 3 recommendations. The parameters that were used included a spray release height of 300 feet, 20 spray lines (aircraft passes) in each application event, a swath width of 499 feet, and a swath displacement based on the

aircraft centerline.

Advanced Settings: Inputs were not changed from Tier 3 recommendations of wind speed height (2 meters), maximum compu te time (600 seconds), maximum downwind distance (795 meters), vortex decay rate (0.56 m/s), aircraft drag coefficient (0.1), propeller efficiency (0.8), and ambient pressure (1013 mb).

AgDRIFT is capable of producing a variety of useful outputs. The key for HED in this assessment was to determine from the model what percentage of the application volume remained aloft and what percentage of the resulting droplets deposited on the surfaces in the

treatment area as well as downwind from the treatment area. AgDRIFT is generally intended to calculate deposition rates in areas that are downwind from the treatment area (i.e., presented from the border of the treatment area to areas of interest downwind). HED has used the values at

the border of the treatment a rea to represent the deposition rate within the treated area. The

results indicate that there is approximately 25% deposition from the edge of the treatment area

and 2.5% deposition 2

, 000 feet downwind. Figure 3.2.1a below shows the AgDRIFT output for

c hlorpyrifos deposition on turf. Based upon the transport of treatment at 300 ft, the airborne

concentration of chlorpyrifos at the breathing height of adults and children is approximately 0.4 ng/L ( 0.0004 mg/m 3 )

. Figure 3.2.1b below shows the AgDRIFT out put for the concentration of chlorpyrifos in air from aerial treatment.Page 85 of 107

Figure 3.2.1a: Estimated Chlorpyrifos Deposition from Aerial Treatment of Mosquitocide at 300 feet Using AgDRIFT

Figure 3.2.1b : Estimated Chlorpyrifos Air Concentration ( Breathing Height of Adults and Children) from Aerial Treatment of Mosquitocide at 300 feet Using AgDRIFTPage 86 of 107

The general assumptions and factors used to assess ULV mosquitocide dermal and incidental

oral exposure include:

the chlorpyrifos ULV mosquitocide labels specify a maximum application rate of 0.01 lb ai/A;

hand

- to

- mouth exposures are based on a frequency of 20 events/hour and a surface area per event of 20 cm 2 representing the palmar surfaces of three fingers;

saliva extraction efficiency is 50 pe rcent meaning that every time the hand goes in the mouth approximately 1⁄2 of the residues on the hand are removed;

object

- to

- mouth exposures are based on a 25 cm 2 surface area;

t he dermal transfer coefficients used are those presented in HED‟s Residential Standard Operating Procedures (SOPs; draft 1997);

high contact lawn activites: 14,500 cm 2 /hr for adults and 5,200 cm 2 /hr for children;

durations of exposure (short

- term) on turf for adults and children is assumed to be 2 hours per day ;

child dermal and incidental oral exposures are combined to represent an overall risk from exposure to turf containing residue from mosquitocide applications.

The general assumptions and factors used to assess ULV mosquitocide inhalation exposure

include:

the entire acti ve ingredient applied by ground to a 1 acre area is airborne and available to be inhaled by a child or adult.

the chlorpyrifos ULV mosquitocide labels specify a maximum application rate of 0.01 lb ai/A;

dilution of airborne concentration of 1 to 100 (i.e ., 1 percent (0.01) of product released is available for exposure from ULV ground application; and

estimated airborne concentrations of chlorpyrifos from aerial and ground ULV applications have been compared to the acute inhalation HEC.

Residential Post

- Application Exposure Studies:

The exposure data used to estimate exposure from golfing on chlorpyrifos treated turf is based upon the following chlorpyrifos TTR exposure study:Page 87 of 107

MRID 44829601 (T urf)

This TT R study (MRID 44829601) e xamined the residues o f chlorpyrifos on turf after application of Dursban® Pro ( an emulsifiable concentrate), Dursban® 50W (wettable powder),

Dursban® 2.5G (granular) and Dursban® 1F (flowable granular) . Three test sites were established in California, Indiana, and Mississippi , with one test plot for each test substance. Single applications of the test products were made to the treatment plots using tractor mounted boom sprayers for the liquid applications and either a tractor mounted air spreader or tractor mounted spreader f

or the granular applications. The liquid applications were made at a nominal application ate of 4 lb ai/A and the granular applications were made at a nominal application rate of 2 lb ai/A. Actual application rates, determined by analyzing filter paper a nchored to the test plots for liquid applications and placing plastic pans in the test plots for granular applications, ranged from 95% to 100% for the Dursban® Pro application, 97% to 102% for the Dursban® 50W application, 91% to 95% for the Dursban® 2.5G application and 77% to 86% for the

Dursban® 1F application. Duplicate samples were collected using the California roller technique at the following intervals: one day prior to the application, just after the application (

- 2.5 hours after application), an d days 1, 2, 4, and 7 afte r application. Samples were analyzed for residues of chlorpyrifos. The overall average concurrent recovery was 98%±3%. The LOD and LOQ were reported as 0.001 μg/cm 2 and 0.003 μg/cm 2 respectively. The field study samples did

no t require correction for field fortification recovery. Average field fortification recoveries (corrected for concurrent recovery), at each of three fortification levels were greater than 90% at

all sites.

Actual average DFR values (corrected for concurr ent recovery) are provided in Table 3.2.1a.

Table 3.2.1a . Summary of Actual Average DFR Values on Turf After One Broadcast Foliar Application of Chlorpyrifos

Sampling

Interval (Days) Actual Ave rage TT R ( μg/cm 2 )

Dursban® Pro (Emulsifiable Concentra te) Dursban® 50W (Wettable Powder) Dursban® 2.5G ( G ranular) Dursban® 1F ( G ranular)

CA IN MS CA IN MS CA IN MS CA IN MS

After 1 st (Only) Application

0 0.124 0.09 0.146 0.234 0.657 0.351 <LOQ <LOQ <LOQ 0.052 <LOQ <LOQ

1 0.039 0.011 0.009 0.027 0.155 0.0 32 <LOQ <LOQ <LOQ 0.02 <LOQ <LOQ

2 0.01 0.005 <LOQ 0.012 0.039 0.006 <LOQ <LOQ <LOQ 0.011 0.003 0.01

4 0.004 <LOQ <LOQ <LOQ 0.005 <LOQ <LOQ <LOQ <LOQ 0.004 0.003 <LOQ

7 <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ

Notes: LOQ = 0.003 μg/c m 2

Residues were corrected for concurrent recoveries. Application rates were a nominal 4 lb ai/A for liquid applications ( Dursban® Pro and Dursban® 50W ) and 2.0 lb ai/A for granular applications ( Dursban® 2.5G and Dursban® 1F).

Residential Post

- applicati on Exposure and Risk Estimates

Risks were calculated using the Margin of Exposure (MOE) approach, which is a ratio of the body burden to the toxicological endpoint of concern. Exposures were calculated by considering the potential sources of e xposure the n calculating dermal, inhalation and non

- dietary ingestionPage 88 of 107

exposures. Short

- term d ermal (adults and children) and incidental oral (children only) exposures to turf following aerial and ground

- based ULV mosquito treatments and adults golfing on treated

tur f were calculated. In addition, acute inhalation exposures to adults and children were estimated from aerial and ground ULV mosquitocide applications. Exposure and risks from residential post

- application uses were calculated in the same manner as describ ed in Section

2.2.1.

A total uncertainty factor of 100 X is appropriate for dermal and incidental oral exposures [ 10X for interspecies extrapolation, 10X for intraspecies variation and a 1X FQPA factor ].

For acute inhalation exposures, a total uncertain ty factor of 300X was applied [3 X for interspecies extrapolation (reduced from 10X because RfC methodology used which takes into consideration the pharmacokinetic differences between animals and humans ), 10X for intraspecies variation, and a 10X FQPA datab ase uncertainty factor (for extrapolation from a

LOAEL to a NOAEL ).

Dermal Exposure from Turf (Adults and Children) and Golfing (Adults)

The approach used to calculate the dermal exposures that are attributable to exposure from contacting turf with chlo rpyrifos deposited from aerial and ground

- based ULV mosquito applications and from golfing on treated turf :

ADD = (TTR t * ET * TC * DA * CF1) / BW

Where:

ADD = average daily dose (mg/kg/day);

TTR t = turf transferable residue on day "0" (μg/cm 2 );

ET = e xposure time (2 hr/day adults and child on turf, 4 hr/day golfing );

TC = transfer coefficient (14,500 cm 2 /hr for adults and 5,200 cm 2 /hr for children on

turf, 3,4 00 cm 2 for adults golfing );

DA = dermal absorption factor;

CF1 = weight unit conversion fac tor to convert μg units to mg for the daily exposure

(0.001 mg/μg); and

BW = body weight (70 kg for adults and 15 kg for children ).

and,

TTR t = AR * F * CF2 * CF3

Where:

AR = application rate (lb ai/acre) x percentage deposited (0.01 lb ai/A)

F = fraction of ai available on the foliage as dislodgeable residue (9.5% aerial,

5.0% ground applications)

t = post

- application day on which exposure is being assessed (day 0)

CF2 = weight unit conversion factor to convert the lbs ai in the application rate to

μg for the DFR value (4.54E+8 μg/lb)

CF3 = area unit conversion factor to convert the surface area units (ft 2 ) in thePage 89 of 107 application rate to cm 2 for the DFR value (2.47E

- 8 acre/cm 2 if the application rate is per acre)

Note: TTR is calculated using the above equation only for the ULV mosquitocide application using deposition percentages for aerial and ground applications. TTR is defined for golfing exposure using measures from chemical

- specific TTR data.

Incidental Oral Exposure from Turf (Children)

The approach used to calculate the incidental oral exposures that are attributable to hand

- to

mouth behavior on treated turf is:

ADD = (TTR t * SA * FQ * ET * SE * CF1) / BW

Where:

ADD = average daily dose (mg/kg/day);

TTR t = turf transferable residue on day "0" (μg/cm 2 );

SA = surface area of the hands (20 cm 2 /event); FQ = frequency of hand

- to

- mouth activity (20 events/hr);

ET = exposure time (2 hr/day);

SE = extraction by saliva (50%);

CF1 = weight unit conversion factor to convert μg units in th e TTR value to mg

for the daily exposure (0.001 mg/μg); and

BW = body weight (15 kg).

Inhalation Exposure (Spray Drift) from Aerial ULV Mosquitocide (300 ft. release height) :

The airborne concentration of chlorpyrifos, 0.0004 mg/m 3 from aerial ULV mosq uitocide treatment was estimated using the AgDRIFT model. This concentration was compared directly

to the acute inhalation HEC to estimate exposure/risk for the exposure scenario.

Inhalation Exposure (Spray Drift) from Ground ULV Mosquitocide:

AC = A R * CF 1 * CF 2 * CF 3 * D

Where :

AC = airborne concentration (mg/m 3 ) ; AR = application rate ( 0.01 lb ai/acre) ; CF 1 = conversion factor to convert lb ai/A to lb ai/ft 2 (1 A/43,500 ft 2 );

Expressed as an airborne concentration: lb ai/ ft 2 = l b ai/ ft 3

CF 2 = conversion factor to convert lb ai/ft 2 to lb ai/m 2 ( 35.3 ft 3 / 1m 3 );Page 90 of 107

CF 3 = conversion factor to convert lb ai/m 3 to mg/m 3 ( 454,000 mg/lb)

D = dilution factor (0.01)

The airborne concentration of chlorpyrifos was estimated using the abo ve formula. As was done for aerial mosquitocide application, this concentration was compared directly to the acute inhalation HEC to estimate exposure/risk for the exposure scenario.

3.2.3 Residential Post

- application Risk Summary

HED has assessed residential post

- application exposures to chlorpyrifos. Short

- term dermal and and incidental oral (children only) exposures to turf following aerial and ground based ULV mosquito treatments are presented in Table 3.2.3a and 3.2.3b, respectively. Acute inhalation exposure following aerial and ground ULV application (spray drift) for adults and children is presented in Table 3.2.3c and 3.2.3d, respectively

. Short

- and intermediate

- term derma l exposure/risk to adults resulting from playing g olf is presented in Table 3.2.3e

.

Estimated short

- term adult and child dermal and child incidental oral exposure to turf following aerial and ground mosquito treatments are not concern to HED (i.e., an MO E > 100). Combined child exposure estimates (dermal and incidental oral) to turf following aerial mosquito treatment

are of concern to HED; however, c ombined estimates following ground treatment are not of concern. Acute adult and child inhalation exposu re following aerial mosquito treatment is not of concern (i.e., an MOE > 30 0 ), but is of concern following ground treatment.

A dult dermal exposure from golfing is not concern to HED (i.e., an MOE > 100) using any TTR region

- specific data for the emulsif iable concentrate formulation at the 1.0 lb ai/A

, or 0.25 application rate s

.

Table 3.2.3a Adult and Child Short

- term Risks (MOEs) from Residential Post

- application Exposure to Turf Following Aerial ULV Mosquito Treatments At 300 Foot Spray Release Heig ht

Children 3 to < 6

Dermal 260

Incidental Oral 130 Combined Exposure 8 8

Table 3.2.3b Adult and Child Short

- term Risks (MOEs) from Residential Post

- application Exposure to Turf Following Ground

- based ULV Mosquito Treatments

Children 3 to < 6

De rmal 1,300

Incidental Oral 670

Combined Exposure 440Page 91 of 107

Table 3.2.3c Adult and Child Acute Risk (MOEs) from Residential Post

- application Inhalation Exposure Following Aerial ULV Mosquito Treatments At 300 Foot Spray Release Height

Children 3 to < 6

I nhalation 1,600

Table 3.2.3d Adult and Child Acute Risk (MOEs) from Residential Post

- application Inhalation Exposure Following Ground ULV Mosquito Treatments

Children 3 to < 6

Inhalation 17

Table 3.2.3e Adult Estimated Short

- and Intermediate

- te rm Risk (MOEs) from Post

application Golfing Exposure to Chlorpyrifos Treated Golf Course Turf ( MRID 44829601) Application Rate

- 1.0 lb ai/A

State Emulsifiable Concn. Granular

CA 8 30 960

IN 1, 200 NA

MS 710 NA

Application Rate

– 0.25 lb ai/A

State E mulsifiable Concn. Granular

CA 3, 300 3

, 800

IN 4,6 00 NA

MS 2,800 NA

3.2.4 Residential Post

- application Exposure and Risk Characterization

Chlorpyrifos occupational use results in the potential for exposure to the general population in

residential sett ings. Adults can be exposed through golfing on chlorpyrifos treated turf and adults and children can be exposed from chlorpyrifos deposition on turf after aerial or ground

based ULV mosquitocide applications. HED has relied upon the Draft SOPs for Reside ntial Exposure Assessment for all scenario s assessed . The data used in the chlorpyrifos residential

post

- application exposure assessment represent the best exposure data and approaches that are currently available. To the extent possible, HED has used ch lorpyrifos

- specific data such as the TTR data used for assessment of exposure to treated golf course turf. Chemical

- specific data for aerial and ground based ULV mosquito uses are not available. For ground based ULV application, HED used data from studie s conducted to measure off site deposition from these applications. Data similar to that for ground applications were not available to determine aerial deposition. I n order to calculate chlorpyrifos deposition on turf from aerial ULV applications,

HED us ed the AgDRIFT (V 2.01) model. Once the deposition input was identified , HED used the high

- end equations and assumptions from the Draft SOPs for Residential Exposure

Assessment to assess turf exposure (dermal and incidental oral) and inhalation exposure f rom aerial and ground based mosquito applications and inhalation exposure from aerial application

. Although the SOPs were initially developed for direct turf applications, the models are used inPage 92 of 107

this assessment to determine if there is a potential concern using a conservative, screening level approach.

HED believes that the values presented in this assessment represent the highest quality results that could be produced based on the currently available post

- application exposure data. Readers

of this doc ument should consider the quality of individual inputs when interpreting the results and make decisions accordingly. It is difficult to ascertain where, on a distribution, the calculated values fall because the distributional data for exposure, residue di ssipation and many other parameters are unrefined. HED does believe, however, that the risks represent conservative estimates of exposure because maximum application rates are used to define residue levels upon which the calculations are based. Additiona lly, estimates are thought to be conservative even when measures of central tendency (e.g., most transfer coefficients are thought to be central tendency) are used because values that would be considered to be in the lower percentile aspect of any input pa rameter have not been used in the calculations.

3.3 Residential Bystander Exposure and Risk

Recently, the Agency has begun exploring the development of an approach for assessing inhalation exposure resulting from the field volatilization of conventional pesticides . The Agency has sought expert advice and input on these issues from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel in December 2009. More information on pesticide volatilization can be found on the Agency‟s website at http://www.epa.gov/opp00001/about/intheworks/volatilization.htm

.

The Agency has developed a preliminary bystander volatilization inhalation exposure assessment

for ch lorpyrifos using currently available inhalation toxicity an d air monitoring data. There are

15 available chlorpyrifos air monitoring studies. These include:

2 application site studies done in Tulare and Lompoc Counties, CA by the California Air

Resourc e Board (CARB), and

13 ambient air studies

o 2 conducted in North Central and Yakima Valley, OR by the University of Washington Department of Environmental and Occupational Health Sciences; and

o 11 conducted by Pesticide Action Network North America (PANNA) , two in Cowiche and Tieton, WA, and nine in Lindsay, CA.

Application site air monitoring refers to the collection of air samples around the edges of a treated field during and after a pesticide application. Samples are generally collected for short

inte rvals (e.g., < 8 hours), for at least the first day or two after application with subsequent samples increasing in duration. In this type of study, it is typically known when an application occurred, the equipment used for the application, and the applica tion rate. Application site monitoring data represents an exposure to vapors at or near the field edge resulting from an application.

Ambient air monitoring typically is focused on characterizing the airborne pesticide levels within

a localized airshed o r community structure of some definition (e.g., city, township, orPage 93 of 107

municipality). This type of monitoring effort also can be focused on capturing chronic background levels or other temporal characteristics of interest such as focusing on seasonal pesticid e use patterns. Typically, samples are taken for 24 consecutive hours and collected at the same site over an extended period of time (e.g., several weeks or months). In contrast to application site air monitoring, information on the precise timing and lo cation of pesticide applications are rarely collected in ambient air monitoring studies. However, this does not mean that an application did not occur near an ambient sampler during the monitoring period

The chlorpyrifos bystander volatilization inhalati on exposure assessment compares the maximum air concentration detected in each of the monitoring studies to the acute HEC for residential bystanders. This comparison was done to represent a potential resident who lives next to a treated field and may be e xposed to the peak concentration of chlorpyrifos volat ilizing

off the field over a 24

- hour period. In addition, the arithmetic mean chlorpyrifos air concentration from each study was compared to the short

- /intermediate

- term HEC for residential bystanders. This comparison was done to represent a potential seasonal exposure. Table 3.3.1 provides chlorpyrifos volatilization MOE calculations for each site. None of the air concentrations results in acute risks of concern; however, there were a couple of aver age air

concentrations from some sites that resulted in short

- /intermediate

- term risks of concern.

Chlorpyrifos Air Monitoring Study Summaries:

Application Site

Washington Department of Health (WA DOH)

– Organophosphorus Pesticide Air Monitoring Project

– Application Site 3 sample types were employed (1 application site and 2 ambient) to determine levels of chlorpyrifos and chlorpyrifos oxon in residential communities in 2 regions, North Central and the Yakima Valley

Near

- field “perimeter” samples were c onducted to determine air concentrations at the edge of an application site A 4 day sampling schedule was used with samples collected on the pre

- spray day, on the spray day and post

- spray days 1 and 2. Sampling occurred at two locations: North Central Peri meter Site and Yakima Valley

Perimeter Site

. North Central Permiter Site (April 6 to April 10, 2008):

o Located in a 4.02 acre study block at the end of a young vertical trellis apple

orchard

.

o Sampling stations were located 25 ft out from the perimeter of th e block (outside row of trees)

.

o A total of 1.5 lbs chlorpyrifos was applied using airblast equipment.

o The maximum chlorpyrifos air concentration measured was 1

, 145 ng/m 3 and the average was 153 ng/m 3 (air concentration measure for chlorpyrifos include the

addition of oxon measures as described in Section 4.0 ). Yakima Valley Perimeter Site (March 31 to April 5, 2008):

o Located in a 5.02 acre study block in a mature traditional apple orchard situated

near a mix of tree fruit blocks.Page 94 of 107 o Sampling stations were loc ated 20 ft out from the perimeter of the block (outside row of trees).

o A total of 10 lbs chlorpyrifos was applied using airblast equipment.

o The maximum chlorpyrifos air concentration measured was 1,002 ng/m 3 and the average was 294 ng/m 3 ( air concentratio n measure for chlorpyrifos include the

addition of oxon measures as described in Section 4.0 ).

Tulare County, CA CARB report from 1998

– Application Site Monitoring Application site monitoring was conducted during June 1996 before, during, and for 72

hour s after an application to an orange grove in Tulare County. Chlorpyrifos was applied via airblast at the rate of 6 lbs ai/A. Samplers were generally placed on each side of the field, at a distance of about 10 to 20 yards from the edge of the field.

The sa mpling schedule is as follows:

o A minimum 1

- hour background sample within 24 hours prior to application.

o A combined sample consisting of sampling during and 1 hour after application.

o A 2

- hour sample from 1 to 3 hours after application.

o A 4

- hour sample fr om 3 to 7 hours after application.

o Two consecutive 8

- hour samples from 7 to 15 and 15 to 23 hours after application.

o Two consecutive 24

- hour samples starting at the end of the second 8

- hour sample.

o The maximum positive chlorpyrifos detection over the samp ling interval was 27,700 ng/m 3 and the average chlorpyrifos air concentration detected was 6,448 ng/ m 3

.

o All of the application samples, including background samples, were found to be above the LOQ of 0.20 ug per sample for both chlorpyrifos and chlorpyrif os oxon (equivalent to an air concentration of 7 ng/m3 for a 24

- hour sample).

Ambient Monitoring

Washington Department of Health (WA DOH)

– Organophosphorus Pesticide Air Monitoring Project

- Ambient Air Monitoring 3 sample types were employed (1 applica tion site and 2 ambient) to determine levels of chlorpyrifos and chlorpyrifos oxon in residential communities in 2 regions, North Central and the Yakima Valley

. “Ambient community” d ata were collected from 4 samplers outside different houses in

residential communities

. N ear

- field “receptor" collection sites were located in areas believed to receive relatively high exposure during airblast applications to tree fruit

. North Central Receptor and Ambient Sites (41 days starting March 24, 2008):

o Samples were co llected over 31 days (due to snow the first 10 days) for 24 hours

at a time

.

o No orchards were within 1,000 meters of ambient sampling sites.

o Every receptor site was in close proximity to (bordered by) a conventional apple orchard, ranging from 9 to 276 fee t away from the nearest orchards

.

o The maximum chlorpyrifos air concentration measured at the ambient site was 21Page 95 of 107 ng/m 3 and the average was 7 ng/m 3 . The maximum measure d at the receptor site s was 607 ng/m 3 and the average was 33 ng/m 3 ( air concentration me asure for chlorpyrifos include the addition of oxon measures as described in Section 4.0 ). Yakima Valley Receptor and Ambient Sites (March 7 to April11, 2008):

o Sampling period was 24 hours with the exception of one 48 hour sample.

o No orchards were within 1 ,000 meters of ambient sampling sites.

o Every receptor site was near conventional apple orchards, ranging from 72 to 1,145 feet away from the nearest orchards.

o The maximum chlorpyrifos air concentration measured at ambient sites was 30 ng/m 3 and the average was 9 ng/ m3

. The maximum measured at the receptor sites was 243 ng/m 3 and the average was 30 ng/m 3 ( air concentration measure for chlorpyrifos include the addition of oxon measures as described in Section 4.0 ).

Lindsay, CA PANNA Drift Catcher report fro m 2005

– Ambient Air Monitoring Collected data from 5 samplers in 2004 (July 13 to August 2) and 4 samplers in 2005 (June 13 to July 22). The samplers ranged from 50 to 400 feet away from orange groves. Monitoring was conducted to coincide with summer use of chlorpyrifos as an insecticide on oranges for the control of lepidopterous pests and scale. It is unknown when applications occurred during the monitoring period. 80% of samples were found to be above the LOQ of 30 ng chlorpyrifos per sample (equivalent to an air concentration of 6 ng/m3 for a 24

- hour sample).

Yakima Valley, WA PANNA Drift Catcher report from 2006

– Ambient Air Monitoring Collected data from a sampler located in Tieton, WA in 2005 (April 1 to 21) and from a sampler located in Cowiche, W A in 2006 (April 3 to 23). The Cowiche sampler was set up 57 feet from the orchard and the Tieton sampler was set up 46 feet from the orchard. Monitoring was conducted to coincide with spring use of chlorpyrifos as an insecticide on apples, pears and cherr ies for the control of coddling moth, leaf roller and other pome

fruit pests. It is unknown when applications occurred during the monitoring period. All 21 samples at both locations were found to be above the LOQ of 20 ng chlorpyrifos per sample (equivalen t to an air concentration of 7 ng/m3 for a 24

- hour sample).

Lompoc, CA CARB report from 2003

– Ambient Air Monitoring Collected data from four samplers located around Lompoc, CA (May 31 to August 3, 2000). Monitoring was conducted around Lompoc because ag ricultural fields dominate the area between Lompoc and the coast. The five major crops or crop groups grown in this area include cole crops (broccoli, cabbage, and cauliflower), lettuce, dried beans, celery, and

flowers. It is unknown when applications oc curred during the monitoring period. 34.2% of samples were found to have at least trace amounts of chlorpyrifos. Only seven samples were found to be above the estimated quantitation limit

.Page 96 of 107

Tulare County, CA CARB report from 1998

– Ambient Air Monitoring Collected data from four samplers located in Tulare County, CA (May 28 to June 28, 1996). Monitoring was conducted in Tulare County, CA because orange groves are predominant

in this area. It is unknown when applications occurred during the monitoring perio d. 74% of samples were found to be above the LOQ of 200 ng chlorpyrifos per sample (equivalent to an air concentration of 9.4 ng/m3 for a 24

- hour sample). The maximum positive chlorpyrifos detection over the sampling interval was 815 ng/m 3

and the average detected was 53 ng/m 3

.

3.3.1 Residential Bystander Exposure and Risk

HED has assessed residential bystander exposure to chlorpyrifos based on the available ambient and application site air monitoring data. The chlor pyrifos bystander volatilization inh alation exposure assessment includes both acute and short

- /intermediate

- term exposure scenarios. The acute scenario compares the maximum air concentration detected in the monitoring studies to the

acute HEC. The short

- /intermediate

- term scenario compares the arithmetic mean chlorpyrifos air concentration from several monitoring studies to the short

- term HEC.

Of the 24 acute ambient air concentrations assessed, 4 result in a risk of concern to HED (i.e., an

MOE < 300). No short

- /intermediate

- term amb ient data assessed result in a risk of concern. Of

the 5 acute application site air conc entrations assessed, 3 resulted in a ri sk of concern. Of the 5

short

- and intermediate

- term application site air concentrations assessed, 4 resulted in risks of

conce rn (i.e., an MOE < 30).

Table 3.3.1 : Chlorpyrifos Preliminary Volatilization MOE Analysis for Residential Bystanders

Study Year

of Study Sampler/Site Location Maximum

Air

Concentration (ng/m 3 ) Arithmetic

Mean Air

Concentration (ng/m 3 ) Acute

MOEs a
(LOC i s an MOE

= 300 ) Short

- /

Int.

- t erm MOEs b

(LOC is

an MOE

= 30 )

Ambient Air Data

Washington DOH 2008 North Central District

Ambient 21 7 29,000 850

North Central District Receptor 607 33 1,000 180

Yakima Valley Ambient 30 9 21,000 620

Ya kima Valley Receptor 243 30 2,500 190

Lompoc County, CA (CARB) 2003 Central 8.3 1.5 19,000 3,800

Northwest 8.4 0.84 19,000 6,800

Southwest 6.8 0.78 24,000 7,400

West 17 2.3 9,400 2,500

Tulare, CA (CARB) 1996 Air Resource Board 39 10 16,000 590 Jefferson Elementary

School 432 94 1,400 61

Kaweah School 412 70 1,500 82Page 97 of 107

Table 3.3.1 : Chlorpyrifos Preliminary Volatilization MOE Analysis for Residential Bystanders
Study Year

of Study Sampler/Site Location Maximum

Air

Concentration (ng/m 3 ) Arithmetic

Mean Air

Concentration (ng/m 3 ) Acute

MOEs a
(LOC i s an MOE

= 300 ) Short

- /

Int.

- t erm MOEs b

(LOC is

an MOE

= 30 ) Sunnyside Union Elementary School 815 52 760 110

University of CA,

Lindcove Field Station 168 39 3,700 150

Cowiche, WA (PANNA) 2006 462 155 350 37

Tieton, WA (PANNA) 20 05 475 182 340 32

Lindsay, CA (PANNA) 2004 Blue House 137 54 1,200 110

Lindsay, CA (PANNA) 2004 Green House 720 120 220 50

Lindsay, CA (PANNA) 2004 Orange House 1,340 190 120 30

Lindsay, CA (PANNA) 2004 Purple House 180 48 900 120

Lindsay, CA (PANNA) 2004 Red House 90 43 1,800 130

Lindsay, CA (PANNA) 2005 Blue House 421 107 380 54

Lindsay, CA (PANNA) 2005 Green House 1,119 177 140 32

Lindsay, CA (PANNA) 2005 Orange House 561 188 290 31

Lindsay, CA (PANNA) 2005 Purple House 515 123 310 4 7

Applicat ion Site Data

Washington DOH 2008 North Central District

Perimeter Site 1145 153 540 37

Yakima Valley Perimeter

Site 1,002 294 620 20

Tulare, CA (CARB) 1996 North 27,700 7,706 22 1

East 14,700 5,974 42 1

South 25,400 5,664 24 1

a. Acute MOE = Acute HEC (620 ,000 ng/m 3 ) / Study maximum air concentration (ng/m 3 ). LOC = 300

b. Short

- term MOE = Short

- t erm HEC (5,700 ng/m 3 ) / Study arithmethic mean air concentration (ng/m 3 ). LOC = 30

3.3.2 Residential Bystander E xposure and Risk Characterization

Some of the limitations and considerations that have been identified that should be considered in the interpretation of these results include:

Most of the data utilized in this preliminary assessment are 24

- hour air samples. When this data is used, an assumption is made that an individual is exposed to the same air

concentration for 24

- hours every day. However, this is not always the case as real world

time

- activity data indicate that many parts of the population move from site to site on a daily basis (e.g., go to work and back).Page 98 of 107

This assessment is only representative of outdoor concentrations (i.e., the exposure and risk estimates assume an individual is outdoors all the time). It does not take into account potential effects of air conditioning syst ems and similar air filtration systems which could potentially reduce air concentrations of chlorpyrifos indoors. The Agency believes that indoor concentrations will be at worst equivalent to outdoor concentrations and may potentially be lower.

All of th e data used for this analysis have been generated in California and Washington ; however, chlorpyrifos is used in many regions throughout the country. Therefore, the results based on the limited available air monitoring data were used to represent the rest of the country due to a lack of adequate information for any other region. It is unclear what potential impacts this extrapolation might have on the risk assessment. Factors such

as meteorology and cultural practices may impact the overall amounts of ch lo rpyrifos that

volatilize from a treated field as well as the rate at which it volatilizes.

As part of the December 2009 SAP, the Agency presented their analysis of several models that could be used as screening tools to predict the air concentration and

volatilization flux based on intrinsic properties and transport behaviors of pesticides. These models would allow the Agency to better represent the potential volatilization of

semi

- volatile pesticides across various regions of the country and thus would provide refinement to this assessment over using straight air monitoring data . The SAP provided a number of comments regarding the Agency‟s model analysis, including the recommendation to evaluate some additional models. The Agency is currently in the

p rocess of evaluating the SAP‟s comments. As appropriate, the Agency will revise the modeling approach presented to the SAP for determining the rate of volatilization (flux)

for semi

- volatile pesticides and for estimating air concentrations of applied pest icides in the atmosphere under varying environmental conditions. After any policies or procedures are put into place, the Agency may revisit the chlorpyrifos residential bystander exposure

and risk assessment.

At this point in time, HED is not including t he residential bystander estimated exposure

in the chlorpyrifos human health risk assessment aggregate due to the limitations surrounding this preliminary assessment.

3.4 Spray Drift

Spray drift is a potential source of exposure to residents nearby to s praying operations. This is particularly the case with aerial application, but, to a lesser extent, could also be a potential source of exposure from the ground application method employed for chlorpyrifos . The Agency has been working with the Spray Drif t Task Force, EPA Regional Offices and State Lead Agencies for pesticide regulation and other parties to develop the best spray drift management practices (see the Agency‟s Spray Drift website for more information at http://www.epa.gov/opp00001/factsheets/ spraydrift.htm). On a chemical by chemical basis, the Agency evaluates the need for interim mitigation measures for aerial applications for placement

on labels/labeling. The Agency has completed its evaluation of the new database submitted by the Spray D rift Task Force, a membership of U.S. pesticide registrants, and is developing aPage 99 of 107

policy on how to appropriately apply the data and the AgDRIFT computer model to its risk assessments for pesticides applied by air, orchard airblast and ground hydraulic metho ds. After the policy is in place, the Agency may seek further refinements in spray drift management practices to reduce off

- target drift with specific products with significant risks associated with

drift.

A quantitative residential post

- application (acu te) inhalation exposure (spray drift) assessment was conducted for ground and aerial ULV mosquitocide applied by a public agency made in the vicinity of residential areas (Section 3 .2 above). HED used AgDRIFT (V 2.01), which is the model that was develope d as a result of the efforts of the Spray Drift Task Force (SDTF) , to determine residue deposition and the airborne concentration of chlorpyrifos anticipated from aerial product application. Based upon this assessment, it was determined that adult and chi ld inhalation exposures following aerial mosquito treatments are not of co ncern to HED (i.e., an

MOE > 300 ). Inhalation exposure from ground based ULV treatment was assessed by assuming that the entire active ingredient applied to a 1 acre area is airborn e and available to be inhaled by

a child or adult. Th e assessment of adult and child acute inhalation from ground mosquito

treatment resulted in a risk estimate of concern to HED.

4.0 Evaluation of Chlorpyrifos Oxon

Chlorpyrifos is activated by desulf uration, reacting in bioactivation to the more toxic and potent acetyl cholinesterase (AChE) inhibitor, chlorpyrifos oxon. The oxon is highly unstable due to rapid deactivation through hydrolytic cleavage by a process called d earylation which releases

TCP

. HED has considered the exposure potential for occupational and residential exposure to chlorpyrifos oxon. Workers reenter ing an environment previously treated with chlorpyrifos (occupational post

- application) and the general population residing near ch lorpyrifos application sites (bystanders) could potentially be exposed to the oxon as chlorpyrifos is metabolized. Dermal exposure to the oxon could occur through contact with chlorpyrifos treated surfaces and inhalation exposure through airborne oxon. However, the likelihood of exposure to the oxon is slight due to its rapid deactivation to TCP. In an effort to further explore the potential for oxon exposure, HED has researched and reviewed all available information sources. Based upon this review, HE D intends to require additional studies to address uncertainties regarding the formation of chlorpyrifos oxon in the air post

- application and its formation and decay in greenhouses.

No occupational exposure studies (handler, post

- application or DFR) were identified that sought to measure the presence of the oxon. Chlorpyrifos and chlorpyrifos oxon were measured in several air monitoring studies (2 application site and 3 ambient air monitoring) conducted to assess inhalation exposure from pesticide volati lization. Study summaries and measured oxon residues are described below in Section 4.1. A search of open literature resulted in 4 metabolism studies which measured whole fruit and leaf surface residue of chlorpyrifos and chlorpyrifos oxon. HED typical ly uses DFR studies, as was done in Section 2.4 of this document, to assess occupational post

- application exposure to handlers based on the contact and

transfer of residues from leaf surfaces. 3 of the 4 metabolic studies identified measured leaf

surface residues in addition to whole fruit/tissue samples. While the fourth study, Diminution of Chlorpyrifos and Chlorpyrifos Oxon in Tomatoes and Green Beans Grown in Greenhouses

,Page 100 of 107

measured only whole fruit resides, it has been determined to be useful as resour ce for characterization of the oxon in an indoor environment. A summary of the studies and results are described below in Section 4.1. HED‟s interpretation and application of the studies is described

in Section 4.2.

4.1 Oxon Study Summaries

Air Monitor ing Data :

Application Site

Washington Department of Health (WA DOH)

– Organophosphorus Pesticide Air Monitoring Project 3 sample types were employed (1 application site and 2 ambient) to determine levels of chlorpyrifos and chlorpyrifos oxon in reside ntial communities in 2 regions, North Central and the Yakima Valley

Near

- field “perimeter” samples were conducted to determine air concentrations at the edge of an application site A 4 day sampling schedule was used with samples collected on the pre

- spray day, on the spray day and post

- spray days 1 and 2. Sampling occurred at two locations: North Central Perimeter Site and Yakima Valley

Perimeter Site.

North Central Permiter Site (April 6 to April 10, 2008):

o Located in a 4.02 acre study block at the end of a young vertical trellis apple

orchard.

o Sampling stations were located 25 ft out from the perimeter of the block (outside row of trees).

o A total of 1.5 lbs chlorpyrifos was applied using airblast equipment.

o The maximum chlorpyrifos oxon concentration meas ured was 61.3 ng/m 3
and the average was 13.5 ng/m 3

. Yakima Valley Perimeter Site (March 31 to April 5, 2008):

o Located in a 5.02 acre study block in a mature traditional apple orchard situated

near a mix of tree fruit blocks.

o Sampling stations were located 20 ft out from the perimeter of the block (outside row of trees).

o A total of 10 lbs chlorpyrifos was applied using airblast equipment.

o The maximum chlorpyrifos oxon concentration measured was 124 ng/m 3 and the average was 27 ng/m 3

.

Tulare County, CA CARB report from 1998

– Application Site Monitoring Application site monitoring was conducted during June 1996 before, during, and for 72 hours after an application to an orange grove in Tulare County. Chlorpyrifos was applied via airblast at the rate of 6 lbs ai/A. Samplers were generally placed on each side of the field, at a distance of about 10 to 20 yards from the edge of the field. The sampling schedule is as follows:Page 101 of 107 o A minimum 1

- hour background sample within 24 hours prior to application.

o A combined sa mple consisting of sampling during and 1 hour after application.

o A 2

- hour sample from 1 to 3 hours after application.

o A 4

- hour sample from 3 to 7 hours after application.

o Two consecutive 8

- hour samples from 7 to 15 and 15 to 23 hours after application.

o Two consecutive 24

- hour samples starting at the end of the second 8

- hour sample.

o The maximum positive oxon detection was 1,850 ng/m 3 over the sampling period and the average chlorpyrifos air concentration detected was 703 ng/m 3

.

o All of the application samp les, including background samples, were found to be above the LOQ of 0.20 ug per sample for both chlorpyrifos and chlorpyrifos oxon (equivalent to an air concentration of 7 ng/m3 for a 24

- hour sample).

Ambient

Washington Department of Health (WA DOH)

– O rganophosphorus Pesticide Air Monitoring Project 3 sample types were employed (1 application site and 2 ambient) to determine levels of chlorpyrifos and chlorpyrifos oxon in residential communities in 2 regions, North Central and the Yakima Valley.

“Ambie nt community” data were collected from 4 samplers outside different houses in

residential communities.

Near

- field “receptor" collection sites were located in areas believed to receive relatively high exposure during airblast applications to tree fruit.

No rth Central Receptor and Ambient Sites (41 days starting March 24, 2008):

o Samples were collected over 31 days (due to snow the first 10 days) for 24 hours

at a time.

o No orchards were within 1,000 meters of ambient sampling sites.

o Every receptor site was in close proximity to (bordered by) a conventional apple orchard, ranging from 9 to 276 feet away from the nearest orchards.

o The maximum chlorpyrifos oxon concentration measured at ambient the sites was 6.2 ng/m 3 and the average was 2.2 ng/m 3 . The maximum m easured at the receptor sites was 110 ng/m 3 and the average was 7.1 ng/m 3

. Yakima Valley Receptor and Ambient Sites (March 7 to April11, 2008):

o Sampling period was 24 hours with the exception of one 48 hour sample.

o No orchards were within 1,000 meters of a mbient sampling sites.

o Every receptor site was near conventional apple orchards, ranging from 72 to 1,145 feet away from the nearest orchards.

o The maximum chlorpyrifos oxon concentration measured at the ambient site was 9.9 ng/m 3 and the average was 3.6 ng /m 3 . The maximum measured at the receptor sites was 21 ng/m 3 and the average was 4.0 ng/m 3

.

Lindsay, CA PANNA Drift Catcher report from 2005

– Ambient Air Monitoring Collected data from 5 samplers in 2004 (July 13 to August 2) and 4 samplers in 2005 (June 13 to July 22).Page 102 of 107

The samplers ranged from 50 to 400 feet away from orange groves. Monitoring was conducted to coincide with summer use of chlorpyrifos as an insecticide on oranges for the control of lepidopterous pests and scale. It is unknown when applica tions occurred during the monitoring period. Chlorpyrifos oxon was not detected in any of the samples.

Yakima Valley, WA PANNA Drift Catcher report from 2006

– Ambient Air Monitoring Collected data from a sampler located in Tieton, WA in 2005 (April 1 to 21) and from a sampler located in Cowiche, WA in 2006 (April 3 to 23). The Cowiche sampler was set up 57 feet from the orchard and the Tieton sampler was set up 46 feet from the orchard. Monitoring was conducted to coincide with spring use of chlorpyrifos as an insecticide on apples, pears and cherries for the control of coddling moth, leaf roller and other pome

fruit pests. It is unknown when applications occurred during the monitoring period. All 21 samples at both locations were found to be above the LOQ of 20 ng chlorpyrifos per sample (equivalent to an air concentration of 7 ng/m3 for a 24

- hour sample). Chlorpyrifos oxon was not detected in any of the samples.

Lompoc, CA CARB report from 2003

– Ambient Air Monitoring Collected data from four samplers l ocated around Lompoc, CA (May 31 to August 3, 2000). Monitoring was conducted around Lompoc because agricultural fields dominate the area between Lompoc and the coast. The five major crops or crop groups grown in this area include cole crops (broccoli, ca bbage, and cauliflower), lettuce, dried beans, celery, and

flowers. It is unknown when applications occurred during the monitoring period. 11.4% of samples were found to have at least trace amounts of the chlorpyrifos oxon. Only one sample was found to be above the estimated quantitation limit

.

Tulare County, CA CARB report from 1998

– Ambient Air Monitoring Collected data from four samplers located in Tulare County, CA (May 28 to June 28, 1996). Monitoring was conducted in Tulare County, CA because orang e groves are predominant

in this area. It is unknown when applications occurred during the monitoring period. 70% of samples were found to be above the LOQ of 200 ng chlorpyrifos oxon per sample (equivalent to an air concentration of 9.4 ng/m3 for a 24

- hou r sample). The maximum positive chlorpyrifos oxon detection over the sampling interval was 230 ng/m 3 and the average detected was 32 ng/m 3

.

Fruit Metabolism Study Oxon Data

Chlorpyrifos Applied to California Citrus: Residue Levels on Foliage and on and in Fruit. Iwata, Y., et al. 1983. American Chemical Society.Page 103 of 107

Lorsban® applied to California orange (Navel and Valencia) and grapefruit trees. Residue data collected to assist in setting worker reentry intervals and legal fruit tolerances. Dissipati on data for chlorpyrifos and its oxygen analogue (oxon) on citrus foliage was determined. Both dissipated rapidly, with the maximum oxon level found was 0.033 μg/cm2 in a 3

- day sample. Application rates ranged from 5.0 to 10. lbs ai/ A for all trees trea ted.

August 1979 : Maximum temperature on the day of application was 32.2 C and for 23 days post

application the daily maximum air temperature was above 35.0 C. Between 7 and 18 days post

application, the temperature was at or above 37.8 C. Chlorpyrif os residues dissipated rapidly

under these conditions.

Chlorpyrifos Residue: For the 5.0 lb ai/A residues were 0.013 and 0.005 μg/cm2 after 4 and 10 days, respectively. At 10.0 lb ai/A residues were 0.031, 0.012 and 0.006 μg/cm2 at 4, 10, and 17 days post

- application. At 10.0 lb ai/A with low volume equipment residues were 0.080, 0.21, 0.015 and 0.008 μg/cm2 at 4, 10, 17 and 31 days, respectively. Due to rapid dissipation, no meaningful dissipation c urve line could be described.

Oxon: No oxon abo ve the 0.01 μg/cm2 level sought was present due to the very rapid disappearance of the parent and likely any oxon formed.

August 1981

- The maximum air temperature was, except for 1 day, at or above 33.3 C for at least 16 days post

- application and 9 of these days had temperatures between 37.2 and 43.3 C. total rainfall over the entire period was 5.9 mm and maximum rainfall over a 24 hour period was

3.3 mm.

Chlorpyrifos Residue: Orange Trees

- For 10 lbs ai/A residues were approximately 0.27, 0.028

a nd 0.008 μg/cm2 after 3, 10 and 17 days post

- application, respectively. For 10 lbs ai/A applied

with low

- volume equipment residues were 0.70, 0.033 and 0.015 μg/cm2, respectively.

Oxon: Orange Trees

– A trace amount of oxon was (0.014 μg/cm2) was found only in the 3

- day sample. One field sample was collected for each of the three replicate field plots on each sampling date for each application rate. The 3

- day sample was approximately 19X below chlorpyrifos measure at the high volume application and 50 X below low volume on the same day

.

Chlorpyrifos Residue: Grapefruit Trees

- For 5 lbs ai/A low volume application residues were approximately 0.40, 0.025 and 0.0070 after days 3, 10 and 17, respectively. For 10 lbs ai/A applied with low volume equipmen t residues were approximately 0.45, 0.90, 0.020 after days 4, 10 and 17, respectively.

Oxon: On day 3 oxon residues were 0.028 and 0.0050 for the 5 and 10 lb ai/ A applications, respectively. On day 10 residues were below LOQ and 0.013 for the 5 and 10 lb ai applications. Day 3 oxon samples were 14X and 90X below chlorpyrifos measured for the 5 and 10 lb applications, respectively

, and below LOQ and 69X below the chlorpyrifos 10 lb application measure for the same days.Page 104 of 107

Diminution of Chlorpyrifos and Chlopyrifos Oxon in Tomatoes and Green Beans Grown in

Greenhouses. J. I. Martinez, et al. 1998. Journal of Ag ricultural and Food Chemistry

.

The study reported the results obtained in different field trials to establish the influence of different grow ing conditions and application rates in the presence of chlorpyrifos and oxon applied on two different commodities. Experiments were conducted in two types of greenhouses in Almeria, Spain: 1) a flat roof greenhouse of polyethylene 2) an asymmetric greenh ouse with a window on the roof. Green beans and tomatoes were grown in 0.5 hectare (1.2 acre) plots incorporating 30

, 000 and 10

, 000 plants, respectively. Dursban® was applied at rates of 0.9 lb

ai/A (half dose) and 1.5 lb ai/ A (full dose) . The treatmen ts were carried out in the spring of 1996 and winter 1997. Samples were collected at random at 0, 0.5, 1, 2, 3, 4, 5, 8 and 15 days after application. Each sample was chopped and divided into four subsamples which were stored

until extraction. Measures were reported in units mg ai/kg sample weight. Chlorpyrifos residue was measured for green beans and tomatoes in winter (full dose), winter (half dose), spring (full dose) and spring (half dose). Corresponding chlorpyrifos oxon residue was measured in th e spring (full dose) sampling period only. For the purpose of this summary review, only spring full dose measures are presented for chlorpyrifos and oxon for comparison.

Chlorpyrifos:

Flat roof greenhouse green beans

- Residue measures approximately 1.70, 1.65, 1.55, 1.30, 1.25, 0.90, 0.80, 0.60 and 0.20 mg/kg at 0, 0.5, 1, 2, 3, 4, 5, 8 and 15 days after application.

Asymmetrical roof greenhouse green beans

– Residue measures approximately 1.70, 1.68, 1.60, 1.40, 1.15, 0.90, 0.75, 0.40 and 0.13 at 0, 0.5, 1, 2, 3, 4, 5, 8 and 15 days after application.

Flat roof greenhouse tomatoes

- Residue measures approximately 1.70, 1.60, 1.20, 1.10, 0.80, 0.70, 0.60, 0.35 and 0.15 at 0, 0.5, 1, 2, 3, 4, 5, 8 and 15 days after application.

Chlorpyrifos Oxon:

Flat roof greenhouse green beans

- Residue measures approximately 0.125 (14X below chlorpyrifos measured ) , 0.17 (10X) , 0.15 (10X) , 0.13 (10X) , 0.20 (6X) , 0.13 (7X) , 0.13 (6X)

, 0.0 and 0.0 at 0, 0.5, 1, 2, 3, 4, 5, 8 and 15 days after application.

Asymm etrical roof greenhouse green beans

– Residue measures approximately 0.125 (14X) , 0.17 (10X) , 0.15 (11 X) , 0.13 (11 X) , 0.20 (6 X) , 0.13 (7 X) , 0.13 ( 6 X) , 0.0 and 0.0 at 0, 0.5, 1, 2, 3, 4, 5, 8 and 15 days after application.

Flat roof greenhouse tomatoes

- R esidue measures approximately 0.125 (14X) , 0.17 (9 X) , 0.15 (8 X) , 0.13 (8 X) , 0.20 (4 X) , 0.13 (5 X) , 0.13 ( 5 X) , 0.0 and 0.0 at 0, 0.5, 1, 2, 3, 4, 5, 8 and 15 days after application.Page 105 of 107

Persistence, Penetration, and Surface Availability of Chlorpyrifos, Its Ox on, and 3,5,6

- Trichloro

- 2

-

pyridinol in Elm Bark. Heng Jin and G. R. Barrie Webster. 1997. Journal of Agricultural and Food Chemistry.

The persistence, penetration and bark surface contact availability of chlorpyrifos and its main degradation products, t he oxon and 3,5,6

- trichloro

- 2

- pyridinol, in elm bark were investigated after chlorpyrifos had been applied to the basal 1 m of elm tree trunks at different application

times and sites. Experiments were carried out in two sites in Canada using Dursban® app lied by backpack sprayer. Samples of elm bark including cambium layer were collected at time 0 (1 hour after), 4, 11, 32, 62, 279, 341, 427, 627, and 791 days after application on August 15, 1991 and 0, 4, 14, 30, 74, 141, 364, 433, and 532 days after app lication on May 7, 1992. The availability of bark surface residues of chlorpyrifos was determined by collecting pressing glass fiber filter paper against the chlorpyrifos treated bark surface for 1 minute. One sample was

taken from one of the three trees in a plot (8 plots total) at each sampling time. No measure of the oxon or pyridinol was collected for the surface residue portion of the study. The initial measure of surface chlorpyrifos was 1.9 mg/m 3 and dropped rapidly to 0.23 mg/m 3 by the 4 day

sam ple. Wood tissue and bark disk samples were also collected to determine the residues present and degradation of these residues in elm bark, cambium and wood tissues. Oxon residues were not detected at any time from samples taken from elm bark at any exper imental site or application time.

The Persistence and Degradation of Chlorthalonil and Chlorpyrifos in a Cranberry Bog. Putnam, R., et al. 2003. Journal of Food and Agricultural Chemistry.

The effect of a spray

- tank adjuvant on the persistence, distri bution, and degradation of two pesticides, chlorthalonil and chlorpyrifos was studied in a commercial cranberry bog. Pesticides were applied according to label instructions to cranberry plants in parallel plot studies. Dislodgeable foliar and whole fruit residues of both pesticides and several degradation products were assessed over a growing season. Residues were also assessed in soil samples collected at fruit harvest. Four experimental plots on an established cranberry bog in Plymouth, MA were

used f or backpack applications of Br avo (chlorthalonil) and Lorsban®® (chlorpyrifos) with and without adjuvant. Adjuvant increased both fruit and foliar residues but did not significantly alter the dissipation rate or metabolism of either pesticide. Chlorpyrif os applications were made at a rate of 2.0 L/ha. Chlorpyrifos applications in the presence of an adjuvant were made at 0.5 L/ha. Foliage samples were initially collected at 1 hour post

- application, followed by 3, 7, 13, and 28 days post

- application using pre

- weighed cotton cheesecloth. Chlorpyrifos was detected in fruit at harvest (62 days post

- application), but no metabolites were found. Chlorpyrifos

- oxon and 3,5,6

- trichloro

- 2

- pyridinol, however, were detected in earlier fruit samples and in foliage and soil samples.

Applications of Lorsban®® in the presence and in the absence of adjuvant resulted in initial (2 hr) dislodgeable foliar chlorpyrifos residues of 125.4 and 52.5 mg/kg, respectively. The dissipation of dislodgeable foliar residues also foll owed first

- order kinetics (r 2 = 0.893 and 0.913) and displayed a more rapid dissipation from cranberry leaves, with estimated half

- lives of 3.3 and 3.8 days in the presence an in the absence of adjuvant, respectively. After 3 days, 33.5Page 106 of 107

and 19.1% of the i nitial residues remained, and after 15 days, 3.0 and 4.9% of the initial residues remained, in the presence and absence of the adjuvant. Small amounts of chlorpyrifos oxon were initially detected (< 7 μg/kg), but residues did not accumulate.

4.2 Interpr etation and Application of Oxon Studies

HED has reviewed the available oxon studies and considered the potential for occupational post

application and residential bystander exposure and risk. Exposure of the general population residing near chlorpyrifos application sites (bystanders) is possible, but the assessment of exposure and risk is characterized by uncertain ty

. Based upon review of the available air monitoring studies which measured the oxon, all application location sites (3) and 4 of the 6

ambie nt monitoring sites had measurable quantities. A comparison of average chlorpyrifos and chlorpyrifos oxon measured (ng/m 3 ) for each site ranged from 4 to 11X below the parent for application air monitoring sites and 2 to 8X for ambient sites (2 had no mea surable quantity and another only had one measure above the level of detection). However, Washington Department

of Health‟s Final Report on the Organophosphorus Pesticide Air Monitoring Project , which summarizes the result of chlorpyrifos and oxon air mon itoring exposure data summarized previously, states the following: “Most samples collected in this study had measurable amounts of either chlorpyrifos or chlorpyrifos

- oxon or azinphos

- methyl

- oxon. Previous studies in California have indicated that the oxy gen analogs can be produced artificially by the sampling process. For example, a chlorpyrifos molecule captured in the air sampling tube can be converted to chlorpyrifos

- oxon during the sampling period.” In such cases, WA DOH elected to

combine the conce ntration of the parent and the oxon to produce a total pesticide concentration for each sample. Furthermore, WA DOH conducted both a laboratory study and a field study to determine the extent to which the oxygen analog of chlorpyrifos could be formed arti ficially during sampling. Preliminary analysis of these studies suggested that some of the oxon

measured in their 2008 sa mples was present in the air sample, and because the oxon is more toxic than the parent it was determined that, “additional research would be conducted to fully characterize potential format ion of oxygen analogs of OP pesticides in the air where OP pestici des are commonly applied.” No further publications from WA DOH regarding the topic

were identified.

HED acknowledges the presence of the oxon in the air monitoring studies; however, it is not

known what the fraction of the oxon residue measured in the studies is present in the environment to be inhaled, or formed in the sampling media. The oxon has been det ermined by

HED to be between 11.9 (acute) and 18X (chronic) times more toxic than the parent. If HED

were to assume 100% formation of the oxon in t he outdoor environment and compare the ratios of oxon to chlorpyrifos measured for each site (as summarized in the previous paragraph), the potential would exist for risk estimates to be of greater concern to HED (i.e., a lower MOE) than the parent for a f

ew of the exposure sites monitored. In order to present a quantification of exposure and risk to the general population residing near chlorpyrifos application sites, additional information is required to address these uncertainties. Specifically, HED nee ds to know whether the oxon concentration measured in the outdoor environment from air monitoring is due entirely to formation in sampling media or if the formation is fractional. If the formation is determined to be fractional, HED needs to know the perc ent of that measured in the sampling media which represents an amount that could be inhaled by the general population.Page 107 of 107

Dermal exposure to the oxon on foliar surfaces from reentry into an outdoor environment previously treated with chlorpyrifos is not an ticipated and, therefore, has not been assessed. The

3 fruit metabolism studies which measured leaf surface residue of the oxon in outdoor environments were either well below the parent (14

- 90X), not detectable, or detected at a level just above the level of detection (LOD). The potential for exposure to the oxon is further minimized due to rapid deactivation of the oxon to TCP. HED‟s review of the fruit metabolism tomato and green bean greenhouse study is not as definitive. HED is concerned, based on s tudy results, that the formation of the oxon may be greater and its deactivation slower in greenhouses when compared to the outdoor environment. The study results indicate that oxon is from 9 to 14X less than the parent from fruit analyzed on the day of a pplication in flat and asymmetric roof greenhouses. The proportion of oxon to parent is less for all days which measurable levels were observed (all but 8 and 15 days after application). The oxon was detected until day 5 with levels

between 5 and 6X belo w that of the parent. It should be noted that residues of chlorpyrifos and oxon were measured from analysis of whole fruit samples and HED typically assesses occupational post

- application exposure and risk based upon the potential for transfer from

extern al, leaf surface residues. The whole fruit samples which include surface residues, as well as residues which may have been contained within the fruit sample likely represent a

conservative measure of available residue because within

- fruit contact is not a nticipated. In order address these uncertainties and more accurately address the risk potential for exposure from occupational reentry into greenhouses treated with chlorpyrifos, HED requires a study to measure chlorpyrifos and oxon residues on leaf surfa ces following treatment with a liquid formulation of chlorpyrifos in greenhouses.