### 2 of 60 

## Table of Contents

Executive Summary ............................................................................................................. ........... 3 1 Introduction .................................................................................................................. ........... 4 2 Use Patterns .................................................................................................................. .......... 5 2.1 Label Requirements Related to Spray Drift ..................................................................... 6 2.2 Typical Uses .................................................................................................................. ... 7 2.3 Use of Aerial Application ................................................................................................ 7 3 Context ....................................................................................................................... ............. 9 3.1 Incident Rates

................................................................................................................. 10 3.2 Stewardship ................................................................................................................... . 11 4 Methods and Inputs ............................................................................................................ ... 12 4.1 Approach ...................................................................................................................... .. 13 4.2 Drift Modeling ................................................................................................................ 14 4.3 Hazard Inputs ................................................................................................................. 16 4.4 Exposure Inputs .............................................................................................................. 18 4.6 Risk Reduction Options ................................................................................................. 21 5 Results ....................................................................................................................... ............ 23 5.1 Drift Estimates ............................................................................................................... . 24 5.2 Risk Estimates From Inhalation Exposure ..................................................................... 29 5.3 Combined Risk Estimates From Lawn Deposition Adjacent to Applications ............... 32 6 Issues For Consideration ...................................................................................................... . 39 7 Conclusions and Recommendations ..................................................................................... 41

Appendix A: Summary of Label Use Patterns Appendix B: Lorsban 75WP Label Excerpt Appendix C: Summary of Use Information Appendix D: AgDrift Screen Shot Appendix E: Results of Drift Modeling Appendix F: Inhalation Risk Calculations Appendix G: Risk Calculations From Deposited Residues on Lawns

### 3 of 60 Executive Summary

This analysis supplements the June 2011 Chlorpyrifos Preliminary Human Health Risk Assessment for Registration Review (HHRA) where limited monito ring data indicate risks to bystanders. 1 

### Bystanders are those who live on, work in or frequent areas adjacent to treated fields. Spray drift can be characterized as th e movement of aerosols and volatile components away from the treated area as a result of the a pplication process. Bystanders can be exposed to spray drift directly or by contac t with resulting deposited residue s. Spray drift of chlorpyrifos was examined using Tier I and II spray drift models to evaluate the impact of varied application conditions. 2 

### The degree of such impacts is governed by many processes ( e.g., application method, nozzles used, release height) and th e conditions at the tim e of application ( e.g., windspeed and direction). Timing and frequency of exposures are also important. Chlorpyrifos is generally not applied multiple times in a year on a per acre basis, so spray drift is sporadic for adjacent properties (most applications are once per year). Residues also quickly degrade on plant surfaces. As such, single day exposures for bys tanders are the focus of this analysis.

Chlorpyrifos labels indicate sprays should not di rectly or through drift contact workers or other persons. Some also indicate sprays should not drift to structures people occupy, associated property, parks or recreation areas. Buffer zones up to 150 feet from the field edge are also required to protect aquatic area s. Ensuring these provisions are adhered to is primarily the responsibility of the user, whic h is reinforced through traini ng, compliance assistance, and enforcement actions, if needed. The degree of drif t in field situations is difficult for users to ascertain at times because observing drift to prev ent all deposits and potential exposure situations can be complex and at times physically impossible. These issues have been discussed extensively in efforts to develop good management pr actices and spray dr ift labeling language. 3



### This analysis focuses on chlorpyrifos applicat ions that comply with application rates and methods identified on product labeling. As explained be low, such applications may still result in drift. This analysis did not focus on circumstan ces leading to the majority of reported drift incidents since it is EPA's assessment that the majority of reported incidents resulted from applications that were plainly not in compliance with label requirements.

Results indicate spray drift from application of chlorpyrifos using current label requirements generally results in risk estimates of concern for locations immediat ely adjacent to treated fields. While risk estimates are of concern adjacent to a field edge for all application methods, implementing buffer zones as appr opriate for residential areas ( e.g. , similar to those in place to address aquatic risk concerns) could allevi ate many of the potentia l human health risks. 4 

### An additional analysis shows shorte r buffers coupled with drift re duction technologies and practices could further alleviate risks in some cases ( e.g., lower application rates, larger droplets, and larger swath displacement).

1 www.regulations.gov (docket ID EPA-HQ-OPP-2008-0850-0025)
2 Peer reviewed modeling approaches were used http://www.epa.gov/scipoly/sap/tools/atozindex/spray.htm and, http://www.epa.gov/pesticides/scien ce/residential-exposure-sop.html

. 3 http://www.epa.gov/pesticides/factsheets/spraydrift.htm provides links to pertinent sources of information
4 http://www.cdms.net/ldat/ld02A011.pdf (pg 3) as an example

### 4 of 60 1 Introduction

Chlorpyrifos is an organophosphate (OP) insectic ide, acaricide, and miticide that controls many foliar and soil borne insect pests. 5 

### Chlorpyrifos was first registered in 1965 for use on a variety of food and feed crops. As chlorpyrifos use e xpanded in agriculture, it also grew in the residential marketplace. Residential use has sinc e diminished because such uses, for the most part, except those with a low e xposure potential, were voluntaril y cancelled and removed from labels in 2001. Even given this trend, exposures can occur in residential environments or other areas frequented by the general publ ic through spray drift. Exposures can also occur as a result of volatilization of chlorpyrifos fr om agricultural crops or other areas after application. These exposure pathways were addressed in the 2011 HHRA using empirical monitoring data. This analysis supplements the previous risk assessmen t by using spray drift models to estimate the potential exposure from a number of different chlorpyrifos applica tion scenarios. This approach allows for a broader understanding of the potential for risk associated with chlorpyrifos spray drift.

Off-target movement of chlorpyrifos can occur via many types of pathways and its magnitude is governed by many processes. Sprays that are off-ta rget can directly lead to exposure. They can also deposit on surfaces where contact w ith residues can lead to exposure ( e.g. , children playing on lawns next to treated fields). The potential exposure and risk estimates from these residues can be calculated using drift modeling and me thods employed for typical residential risk assessments. There is precedent for using this approach as it mirrors the methods used in a response to a petition to cancel 14 pesticides as well as methods used to develop buffer zone estimates for use of two organophosphate ins ecticides on orchard crops in the Pacific Northwest. 6



### Volatilization can occur during or after application. It can re sult from aerosols evaporating during application, while deposited sprays are still drying, or after application as dried deposited residues volatilize ( e.g. , possibly via co-disti llation). This document addresses only those exposures associated with spray drift and whatev er volatilization is anticipated to occur during application.

AgDRIFT (V2.1.1) and AgDISP (V8.26) were used to provide deposition values for residential lawns, as a fraction of the appl ication rate, at different distan ces downwind of a treated field. AgDRIFT (V2.01) was used to estimate air concen trations at different distances downwind of a treated field. Distances up to 125 feet away were considered in both of these analyses. Both the drift and exposure methods used to quantify the potential risks from pesticide spray drift were previously peer reviewed through the FIFRA Scientific Advisory Panel). 6

5 http://www.cdms.net/manuf/mprod.asp?mp=11&lc=0&ms=3691&manuf=11 (see Dursban or Lorsban labels)
6 http://www.epa.gov/scipoly/sap/tools/atozindex/residentexp.htm
, http://www.epa.gov/scipoly/sap/meetings/2009/100609meeting.html , and http://www.epa.gov/scipoly/sap/tools/atozindex/spray.htm

### 5 of 60 In addition to spray drift deposition and air conc entration determinations, other aspects of this analysis are based on methods commonly used for evaluating risks from pesticides used on turf because the risk concern is base d on drift depositing on lawns adj acent to treatment sites. This scenario is utilized be cause it represents the hi ghest potential for exposure associated with spray drift and it also considers different human lifesta ges, including those associated with children at different developmental stages. 7 

### Data from a chlorpyrifos stud y that determined turf residue levels and dissipation rates after application were also available. 8 

### These data were used in conjunction with the standard resi dential methods to estimate expos ure from treated turf. Finally, the endpoints and points of departur e (PODs) used for this analysis are similar to those used in the 2011 HHRA. The PODs used were defined ba sed on route-specific studies that can be considered of high quality and suitable for risk assessment purposes. In some cases, PODs differ slightly from the 2011 HHRA because these valu es are more appropriate for evaluating infrequent, single day expos ures like those anticip ated with spray drift. 9



### Section 2
, Use Patterns provides an overview of how chlorpyrif os is used with a specific focus on spray drift. Section 3
, Context includes information on related topics such as the nature and frequency of incidents and efforts to develop best management prac tices for spray drift that must be considered when interpreting the results of this analysis. Section 4
, Methods and Inputs provides more details on the sp ecific calculations and values used to define risks from chlorpyrifos spray drift. The calcula ted risk estimates are provided in Section 5
, Results . Issues that should be considered, specifi c to how the risk estimates from spray drift were calculated, are presented in Section 6
, Issues for Consideration

. Section 7
, Conclusions and Recommendations , presents the conclusions of this assessment and describes potential mitigation measures that could be adopted and th eir impact on the calculated risk estimates.

2 Use Patterns

Chlorpyrifos is a broadly used organophosphate insecticide currentl y registered for the control of various insects. Registered us e sites include: food crops includi ng fruits, nuts, vegetables, and grains and non-food crops such as golf course turf, industrial sites, greenhouses, nurseries, sod farms, and wood products. Public health uses in clude aerial and ground-based fogger treatments to control adult mosquitoes. There is a wide range of currently regi stered chlorpyrifos application rates. In general, current maximum chlorpyrif os application rates do not exceed 4 lb ai/a nationwide; however, single application rates grea ter than 4 lb ai/a are currently permitted for some specific use patterns. For example, a single ch lorpyrifos application of 6 lb ai/a is permitted on citrus in a limited number of counties in Cali fornia. In addition there are also spot or trunk drench applications that may result in single a pplication rates higher than 4 lb ai/a. A summary of the chlorpyrifos use pa tterns including applicati on rates is presented in Appendix A

. Other information related to how chlorpyrifos is used germane to the exposure potential from spray drift and characterizing potential mitigation options is presented below. Specifically,

7 http://www.epa.gov/pesticides/scien ce/residential-exposure-sop.html
8 (Stafford et al,1999) Determination of Dislodgeable Foliar Residues on Turf Treated With Formulations Containing Chlorpyrifos (EPA MRID 44829601).
9 Should changes in the hazard evaluation occur they w ill be reflected in this analysis as appropriate ( e.g., impact of findings of 2012 FIFRA SAP, http://www.epa.gov/scipoly/sap/meetings/2012/041012meeting.html ).

### 6 of 60 Section 2.1 summarizes the requirements to ensu re applications are made using a best management practices approach. Typical chlorpyrifos use practices are presented in Section 2.2

. Section 2.3 discusses the significance of aerial application as a me thod for using chlorpyrifos ( e.g. , prevalence on certain crops).

2.1 Label Requirements Related to Spray Drift

Current chlorpyrifos labels provide guidance fo r users on how to reduce the potential for spray drift under actual use conditions. Many of thes e criteria have long been recognized in the scientific literature as key f actors related to how changes in application technology will impact spray patterns and the subsequent drift. The Dow AgroSciences product Lorsban Advanced label has been used to illustrate this guidance (EPA Reg. No. 62719-591). All current chlorpyrifos labels contain similar labeling language. This gui dance serves as the basi s for the drift modeling described below. The label language under the section, Spray Drift Management , is included as Appendix B . A few key elements are summarized below.

The label prohibits drift from contacting people, the structures they occupy, and associated property at any time. The label also indicates avoiding drif t is the responsibility of the applicator and that they should consider equipment and weat her related factors when making applications. Buffer zones are also specified for applic ations around aquatic ar eas as described in Table 1

. Table 1. Current Buffer Zones for Chlorpyrifos Around Aquatic Areas

Application Method Required Buffer Zone (feet)
Groundboom 25 Chemigation 25

Airblast 50 Aerial (fixed wing or helicopter) 150



### The Lorsban label also provides best management practices to reduce spray drift. Guidance is provided that describes how applic ators should consider the conditi ons of the site when deciding how and when to make an application ( e.g. , presence of possible atmospheric inversion conditions, location of sensitive site s such as residences relative to site location). Additionally, the label provides information for specific a pplication methods. Some examples include:

• For Aerial Applications - Nozzles must produce a medium or coarser droplet size (255 to 340 microns volume median diameter) pe r ASABE Standard 572 under application conditions and applications must not be made at a height greater than 10 feet above the top of the target plants unless required for aircraft safety.

• For Groundboom Applications - Choose only nozzles and pressures that produce a medium or coarse droplet size (255 to 400 microns volume median diameter), per ASABE Standard 572 and do not apply pr oduct when wind speed exceeds 10 mph.

### 7 of 60 •For Orchard Airblast Applications - Apply only when wind speed is 3 to 10 mph and spray the outside rows of orchards from outsi de in, directing the sp ray into the orchard and shutting off nozzles on the side of the sprayer away from the orchard.

2.2 Typical Uses

This section provides use information such as the application rate and number of applications for national-level total chlo rpyrifos used (in all formulations and with all application methods combined) on use sites where information was available. Details are available in Appendix C

. Approximately 8 million pounds of chlorpyrifos are used annually in agriculture. Total chlorpyrifos usage varies widely with average percent crop treated (PCT) - a measure of the area treated with chlorpyrifos in th e survey years (2006-2010, unless ot herwise noted) - as low as 1% for several crops and as hi gh as 62 % (for apples) ( Appendix C ). The five crops with the highest PCT are apples (62% PCT), broccoli (55%), wa lnuts (46%), onions (45%), and cauliflower (41%).

Corn and soybean are the two crops with highest total amount of ch lorpyrifos used in terms of average pounds applied – both show ove r 1,000,000 lb used across the years ( Appendix C ). Crops that have low total chlorpyrifos usage (a rbitrarily defined as less than 20,000 pounds used, on average) but show relatively large area treated (arbitrarily defined as greater than 25% average percent crop treated, or PCT) include strawberries, aspara gus, and cauliflower.

Nineteen crops (out of a total of 39 crops surv eyed) show average application rates that are approximately 1 lb ai/a. These crops are ap ples, almonds, broccoli, cabbage, cauliflower, cherries, grapefruit, hazelnuts, lemons, oranges, peaches, peanuts, pears, plums/prunes, pumpkins, squash, sweet corn, tobacco, and walnuts. The frequency of application, on average, for most crops is one time per year. In a few crops, the annual average frequency of application is approximately two times per year. This in formation supports the supposition that focusing on single day exposures on a per acre basis from spray drift is an appropriate premise.

2.3 Use of Aerial Application

The usage information on aerial applications wa s obtained from a private marketing research database that stores results of annual market surv eys that cover the continental United States and the majority of crops produced ( Table 2 ). 10 

### These should be considered in the context of the percent crop treated inform ation described above in Section 2.2 . The surveys utilize sampling procedures that result in statistically valid result s for most crops. However, due to limited sample size, precision is reduced for some crops and for crops with limited use of chlorpyrifos. Data from 2006 to 2010 were used in this analysis, and the resu lts presented are an average of the five years of data. The rate range information for each crop was obtained by querying the proprietary source database.

10 A similar analysis was conducted in order to evaluate the import of ground applications. A table analogous to Table 2, excerpted from that memo, is included as part of Appendix C for informational purposes. It is not included here since ground applications are predominant and they do not represent the most significant risk concern, as will be detailed below.

### 8 of 60 The application method rate range data was summ ed over the five years for each rate range in which applications were reported and the percentage of applica tions in each rate range was calculated for aerial applications. The maximum obser ved rate for aerial applications is the last column in Table 2 . The maximum label rates may be higher than these maximum observed so it is possible that higher rates might have been used. However the maximums reported were the highest rates observed over a five year period so a significant number of applications at higher rates are unlikely.

The approximate percentage of the crop treated by air was calculated. This calculation assumes that the average number of applications were the same for aerial app lications as for all applications. This assumption is justified because the average number of applications for most crops is once per year.

For most crops the acreage treated with aerially applied chlorpyrifos represents only a small percentage (<10%) of the total crop acreage. Nevertheless, for some crop aerial applications are important ( e.g., 80% of sunflower chlorpyrifos applica tions are made by air). Nine percent of asparagus acres were estimated to have been treated by air. An estimated five percent of sunflowers and sweet corn were tr eated with aerial appl ications of chlorpyrif os and for all other crops less than five percent of planted acres received aerial applications of chlorpyrifos. Maximum observed application rates varied significantly among crops, with some receiving maximum application rates of one pound of act ive ingredient per acre while maximum application rates for lemons and oranges were 5.7 and 6 pounds per acre respectively. Citrus crops (alone) have an additional label, limited for use only in the San Joaquin Valley of California (Fresno, Tulare, Kern, Kings, and Madera counties), that permits use of rates up to 6 lb ai/a; all other citrus has a maximum application rate of 4 lb ai/a.

Table 2. Aerial Applications of Chlorpyrifos to Crops (2006-2010)

Crop % of Applications Applied by Air % of Total Crop Acreage Treated by Air Average Lbs AI Year Applied by Air Average Application Rate (lb ai/a)

for Aerial Applications Maximum Rate (lb ai/a) Observed for Aerial Applications (rounded up) Alfalfa 31 1 130,000 0.5 1.0 Almonds 14 3 60,000 1.9 2.0 Apples 5 3 15,000 1.0 2.0 Asparagus 24 9 4,000 1.0 1.0 Beans (Snap) <1 <1 <100 0.8 0.8 Broccoli <1 <1 <100 1.0 1.0 Cabbage <1 <1 <100 1.0 1.0 Cauliflower 1 1 200 0.9 1.0 Cherries 2 1 700 0.9 1.0 Corn 2 <1 20,000 0.8 2.0 Cotton 8 <1 40,000 0.8 1.0 Cucumbers None Dry Beans 17 <1 2,000 0.5 1.0 Grapefruit 2 <1 700 1.5 1.5

### 9 of 60 Crop % of Applications Applied by Air % of Total Crop Acreage Treated by Air Average Lbs AI Year Applied by Air Average Application Rate (lb ai/a)

for Aerial Applications Maximum Rate (lb ai/a) Observed for Aerial Applications (rounded up) Grapes, Raisin None Grapes, Table <1 <1 150 1.0 1.0 Grapes, Wine None Hazelnuts 32 4 1,000 1.0 2.0 Lemons 4 2 3,000 2.7 5.7 Onions <1 <1 <100 1.0 1.0 Oranges 7 2 30,000 1.8 (2.5) 6.0 Peaches 5 1 2,000 1.1 3.0 Peanuts 2 <1 2,500 1.4 1.8 Pears 3 1 800 2.0 2.0 Peas (Fresh) None Pecans 15 4 40,000 0.9 (1.5) 2.0 Peppers 7 <1 <100 0.3 0.3 Plums/Prunes None Potatoes 8 <1 200 1.0 1.0 Pumpkins None Sorghum 18 <1 2,000 0.5 0.8 Soybeans 16 1 600,000 0.4 (0.8) 1.0 Squash 1 <1 <100 3.0 3.0 Strawberries None Sugar Beets 13 1 10,000 0.6 1.2 Sunflowers 80 5 50,000 0.5 (0.7) 1.0 Sweet Corn 43 5 30,000 0.6 2.0 Tobacco None Walnuts 6 3 25,000 1.9 (2.0) 3.0 Wheat, Spring 38 1 50,000 0.4 (0.5) 1.0 Wheat, Winter 30 1 110,000 0.4 (0.5) 1.0 Note: For some crops there are single/very few observations so this should be considered in the interpretation of the information presented in this table.



### 3 Context

In late 2009, a policy paper focusing on the deve lopment of updated methods for conducting risk assessments for workers and for those who live in proximity to agricultural pesticide use sites was released. 11 

### Status updates of this policy have also been presented at several meetings of the Pesticide Program Dialogue Committee (PPDC). A pub lic comment period was utilized to solicit input from stakeholders. 12 

### A key aspect of this policy is that the Agency committed to

11 http://www.epa.gov/pesticides/health/worker-rsk-assmnt.html , also see www.regulations.gov docket ID EPAHQ-OPP-2009-0889-0002
12 For example, refer to http://www.epa.gov/oppfead1/cb /ppdc/2011/april/april2011.html

### 10 of 60 developing an approach for charac terizing potential exposure and ri sk estimates associated with off-target chemical movement via spray drift. The plan for implementing this policy is through the Registration Review process wi th an initial focus on uses with a perceived high risk potential.

There are many ways the potential risk associated with pesticide spray drift can be considered in the regulatory process. It is important to cons ider all mitigation alternatives in order to be expedient, thorough, and cost effective ( e.g., changes to application rate s, changes in application parameters, buffer zones). For example, if a pestic ide can be used to trea t lawns directly without a risk estimate of concern, then calculating risks via spray drift, given similar application rates, may not be needed because the risks from drift c ould be the same or lower than that associated with the direct application to lawns. In other cases, like with chlorpyrifos, uses in the residential marketplace are restricted. In these situations, many factors ar e important for describing the potential for risks via drift including: applicati on methods for particular crops, prevalence of use on a particular crop or application method, need fo r a pesticide relative to the pest of concern, environmental fate characteristics of a pesticid e, and the toxicological characteristics of the pesticide. Many of these factors were consider ed in this analysis and are described.

In addition to label stipulations that dictate how a pesticide can be used and the factors that can impact exposures via drift (described above in Section 2.1 ), other relevant information should be considered including a discussion of incident rates and causes. Incidents are important for characterizing the results of th is analysis and are summarized based on the 2011 human health risk assessment in Section 3.1 . The Agency and stakeholders have also been working to develop guidance related to managing spray drift using a be st practices approach as described below in Section 3.2

. 13 

### These efforts have prompted methods development for evaluating the performance of drift reduction technologies, an important basis for developing viable mitigation options.

3.1 Incident Rates

The conclusions of the most recent evaluation of the incidents associated with chlorpyrifos use indicate incidents have declined substantially am ong residential users. This would be expected given that most residential uses, except produc ts that are known to produce lower levels of exposure, were voluntarily cancelled and removed from labels at the end of 2001. 14 

### At the same time, occupational incident rates have remained fairly constant over time. The conclusions that were made associated with the 2011 HHRA indicat e that the overall numbe rs and severity of incidents associated with chlorpyrifos use do not represent an immediat e public health concern ( e.g., serious non-reversible effects or deaths have not been seen as a result of chlorpyrifos drift). For the most part, they also have been cause d by some manner of accident, operator error, or misuse ( e.g., direct drift onto individual s in adjacent properties). Th ese incidents differ from the drift calculations contained in this analysis becau se this analysis is based on the premise of label compliance.

An evaluation of the National Institute fo r Occupational Safety and Health (NIOSH) Sentinel Event Notification System for Occupational Risks (SENSOR) information indicates issues

13 http://www.epa.gov/pesticides/factsheets/spraydrift.htm
14 Recore and Oo (6/27/11) Chlorpyrifos: Tier II Incident Report (D388406)

### 11 of 60 associated with application appear to be the leading cause of the reported incidents involving chlorpyrifos, and responsible for 46% of those incidents reported from 1998 to 2007. The California Pesticide Illness Surveillance Program (P ISP) also reported incidents associated with chlorpyrifos and it appears that drift from adj acent fields may be the cause of most of the reported incidents, unlike the SENSOR results. Sp ray drift is responsible for 56% of the cases reported to PISP from 1999 to 2008 ( Figure 1 ). These incidents appear to be predominantly caused by drift contacting workers in fields adjace nt to application events, which is a misuse based on current labels. An exampl e includes a large 2007 incident ( i.e., impact on large number of people) in Tulare County California associated with an airblast applica tion of chlorpyrifos to almonds that impacted 28 workers who were working in an adjacent vineyard.

Figure 1. Chlorpyrifos CA PISP Occupational Incident Summary

A separate published analysis of drift incide nts developed by NIOSH SE NSOR investigators was also considered. This analysis i ndicated chlorpyrifos ha s a relatively high rate of incidents due to drift compared to the other pesticides addressed in the analysis. 15 

### The authors indicated 49 out of 1809 total cases ( i.e., incidents) across all pesticides consid ered, where the cause was related to a single pesticide, could definitively be associated with exposure to chlorpyrifos. Ten of these were defined as being of moderate to high sever ity. Additionally, the authors noted the Tulare County incident described above was one of the 10 largest ( i.e., most impacted people) incidents that occurred between 1998 and 2006 associated with spray drift.

3.2 Stewardship

As mentioned previously, the issu e of spray drift, including de veloping a workable strategy for ensuring proper stewardship by users, has been a longstanding issue. These efforts have been formalized with the development of a draft PR notice (2009-X: Draft Pe sticide Drift Labeling) which provides guidance to pestic ide registrants on how to minimi ze drift and to protect people, non-target organisms, and the envi ronment from adverse e ffects that may be caused by off-target

15 Lee et al (2011) Acute Pesticide Illnesses Associated w ith Off-Target Pesticide Drift from Agricultural Applications — 11 States, 1998–2006, available at the following: http://ehp03.niehs.nih.gov/article/info%3Adoi%2F10.1289%2Fehp.1002843

### 12 of 60 pesticide drift. 16 

### Current chlorpyrifos labels in many ways reflect the guidance outlined in the PR Notice 2009-X: Draft Pestic ide Drift Labeling (see Appendix B ). This includes overall guidance and recommendations for users to evaluate field and atmospheric condition s prior to and during application to ensure drift potential is minimize d, particularly if ther e are areas nearby where people live or that could be considered sensitive.

The draft PR Notice also outlines a plan fo r developing a Drift Reduction Technology (DRT) program. DRTs represent many possible applica tion technologies that offer the potential to reduce drift from pesticide applications. Even though some of these techniques are widely recognized for reducing drift poten tial, limited information exis ts to quantify their actual effectiveness. The DRT provides application equipment and spray adjuvant manufacturers with a test method and a process for voluntarily testi ng and validating technolog ies for drift reduction potential. Tested technologies that are proven to significantly reduce drift will be assigned a rating and listed on the Agency’s website. Pesticid e registrants will then be able to choose to recommend or require through pe sticide product labels the use of validated DRTs for product application as a drift mitigation measure. EPA w ould consider label DRTs in its risk assessment and risk management decisions for the registra tion of these products. La beling that cites DRTs could provide applicators who employ them more flexibility for modifying equipment and techniques in order to reduce drif t potential for the specific use scenario. In effect, use of DRTs is a performance based approach that lets users employ the mean s at their disposal to reduce drift. Note: DRTs are described in detail in the dr aft PR Notice if further in formation is desired.

Managing the drift pot ential from applications of chlorpyrif os is a key concern. In the PR Notice example, different application pa rameters are associated with di fferent possible buffer distances. Such application parameters include varying th e droplet size, allowing for different wind speeds at application, and fixing boom si ze relative to the wingspan of a plane or the helicopter rotor. The evaluation of drift potential for chlorpyrif os and the associated risk estimates were developed in a manner that is consistent with the draft PR Notice and the DRT performancebased construct. A series of po ssible drift reduction measures and the associated impacts were evaluated as part of this analys is as potential refinements to ex isting chlorpyrifos labels and may also be used as a guide for the development of data consistent w ith the DRT approach.

Finally, many of the approaches that are currently being implem ented as part of the overall strategy for reducing risk estimates associated w ith fumigants could also be effective for spray drift concerns. 17 

### This is especially true of some of the qualitative measures like enhanced training, site specific management plan s, and record keeping requirements.

4 Methods and Inputs

The approach used to evaluate the drift potential and associated risks for chlorpyrifos is based on standard methods and inputs. Section 4.1 describes the overall approach used for this spray drift
assessment. Section 4.2 describes the models used, inputs, and limitations used to define the degree of drift associated with each application method evaluated. Section 4.3 summarizes the

16 Available at www.regulations.gov (docket ID EPA-HQ-OPP-2009-0628-0002), also refer to (docket ID EPAHQ-OPP-2009-0628-0003) which provides examples to aid with interpretation of the PR Notice
17 http://www.epa.gov/opp00001/reregistration/soil_fu migants/implementing-new-safety-measures.html

### 13 of 60 toxicological characteris tics of chlorpyrifos. Section 4.4 describes the values and methods used to calculate the exposures, once the drift poten tial was defined, for risk assessment purposes. Similarly, Section 4.5 describes the values and methods us ed for risk calculation purposes. Finally, Section 4.6 describes the possible DRTs that were considered as viable measures for reducing risk estimates and how they were integrated into the analys is in order to illustrate their potential impacts.

4.1 Approach

Pesticide spray drift can potentially impact thos e who are in proximity to application events through a variety of possible exposure pathways. In order to evaluate the drift potential and associated risks, an approach based on drift mo deling coupled with techni ques used to evaluate residential uses of pesticides was utilized. E ssentially, a residential turf assessment based on exposure to deposited residues has been completed for each scenario, but the source term used to define these residues was determined in a differe nt manner and is based on the amount of spray drift that may occur as illustrated in Figure 2



### .

Figure 2. Conceptual Model of Exposure Pathway Associated With Spray Drift

In this case, drift modeling was completed for a variety of applicati on scenarios including different application equipment, sp ray types, and windspeeds. This approach is also protective of other possible types of pathways because the exposures used as th e basis for these calculations are protective of other possi ble exposure situations ( i.e., children’s exposure on treated turf yields significantly higher estimates than other po ssible scenarios). It also is a logical exposure pattern that would reasonably be expected to oc cur with a spray drift event, given that children could play on lawns adjacent to treated fields . Along with these types of exposures, airborne concentrations of chlorpyrifos were also defined and used to estimate risks from inhalation exposure. For this calculation, concentrations we re defined in the breathing zone (area around the nose, ~ 3 to 5 ft above ground for this analysis) at the edge of the 50’ wi de lawn closest to the treated field. Chlorpyrifos is generally not applie d multiple times in a year on a per acre basis, so

### 14 of 60 spray drift is only anticipated spor adically on adjacent properties. As such, there is a focus in this assessment on single day exposures for individuals who may live on or frequent such properties.

4.2 Drift Modeling

Tier I spray drift analysis for aerial, ground, and orchard air blast applications of chlorpyrifos were completed using AgDRIFT 18 

### (v2.1.1) to investigate the depos ition pattern of chlorpyrifos downwind of a treated field. 19 

### The AgDRIFT spray drift mode l is a Microsoft Windows-based computer program provided to the U.S. Environm ental Protection Agency’s Office of Pesticide Programs as a product of the Cooperative Research and Development Agreement (CRADA) between EPA’s Office of Research and Developm ent and the Spray Drift Task Force (SDTF). AgDRIFT predicts the motion of spray material released from aircraft, including the mean position of the material and the position varian ce about the mean as a result of turbulent fluctuations. AgDRIFT has undergone extensiv e validation including evaluation by a FIFRA Scientific Advisory Panel. 20, 21



### Tier I AgDRIFT is a regression model develo ped from SDTF data including more than 300 applications made in 10 field st udies covering a range of applicat ion practices for each type of application ( i.e. , aerial, ground, and orchard air blast app lications). AgDRIFT has been formally validated by comparing its predic ted outputs to 180 SDTF field trials. These data were generated for aerial applications to a distance of about 800 meters downw ind of the application field edge. These field trials were conducted using pesticide ( i.e. , dissolved or emulsifiable) in a liquid spray and therefore they may not fully represent spray drift resulting from en capsulated or granular based pesticide formulations . If these formulations ( e.g. , dispersible capsules or dispersible granular) are applied using a liqui d carrier and the droplet size di stribution is the same as those droplet size distri bution included in AgDRIFT the resulting spray drift values are assumed to be the same. Granular formulations ha ve different drift patterns than for liquid sprays, and as such need to be considered in a separate analysis. Ho wever, from a human health perspective, off-site movement of granular products would result in lower risk estimates than those for liquid products ( e.g. , less drift occurs and there is less exposure uptake for granules).

Deposition rates were determined as a fraction of the application rate ( i.e. , how much of the target application rate is predic ted to be deposited at various distances downwind of the treated field). This fraction of the appl ication rate was adjusted based on the range of currently approved application rates (1 to 6 lb ai/a) for various crops to determine the average effective deposition

18 A User’s Guide for AgDRIFT 2.1.1: A Tiered Approach for the Assessment of Spray Drift Pesticides (February 2003). AgDRIFT V2.01 was used to model inhalation exposure concentrations.
19 AgDRIFT and AGDISP models: Models are ava ilable through Harold Thistle, US Forestry, hthistle@fs.fed.us

. 20 U.S. Environmental Protection Agency. Federal Insecticid e, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel: Estimating Drinking Water Exposure as a Component of the Dietary Risk Assessment; Spray Drift Program, December 10-11, 1997

. 21 U.S. Environmental Protection Agency. Federal Insecticid e, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel: Burholderia cepacia: Risk Assessment of a Biopesticide with Affinities to a Human Opportunistic Pathogen; A Consultation on Protocol Design to Assess Acute Neurotoxicity Studies following Oral Administration of Pesticides; Higher Tier Ecolog ical Risk Assessment for Chlorfunapyr; Spray Drift - Review of Proposed Pesticide Deposition Curves to Adjacent Areas, July 20-23, 1999

.

### 15 of 60 rate (lb ai/a) at various distances downwind of the treated field for each respective crop use. Input parameters used in the Tier I spray drift analysis are provided in Table 3

. Table 3. Tier I AgDRIFT Input Parameters Parameter Value Comments Aerial Equipment Air Tractor AT-401 AgDRIFT default option Release Height 10 ft AgDRIFT default values

Wind Speed 10 mph AgDRIFT default values / Chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) restricts applications to periods when the wind speed is between 3-10 mph. Surface Roughness 0.0075 m (0.3 in) Default Temperature Not specified AgDRIFT Tier I ground models are based on regression equations developed on empirical data.

Swath Displacement 0.3702 (F2M) 0.2781 (M2C) 0.2149 (C2VC) AgDRIFT default values/ Chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) restricts applications to droplet sizes greater than 255 μM.

Droplet Size F2M, M2C, C2VC Chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) restrict applications to droplet sizes greater than 255 μM; therefore, only droplet distributions with a mean diameter (D v0.5 ) ≥ 255 μM were selected for modeling. Fine to Medium (F2M): Droplet size (D v0.5 ) = 255 μM Medium to Coarse (M2C): D v0.5 = 341 μM Coarse to Very Coarse (C2VC): D v0.5 = 439 μM 

### Ground 1

Equipment Low Boom (LB) High Boom (HB) AgDRIFT default options

Release Height LB: 0.508 m (20 in) HB: 1.27 m (50 in) AgDRIFT default values

Application Efficiency LB: 99.27 HB: 99.22 AgDRIFT default values

Wind Speed Not specified AgDRIFT Tier I ground models are based on regression equations developed on empirical data. Surface Roughness Not specified AgDRIFT Tier I ground models are based on regression equations developed on empirical data. Temperature Not specified AgDRIFT Tier I ground models are based on regression equations developed on empirical data. Swath Width 13.72 m (45 ft) AgDRIFT default value

Droplet Size F2M/C Chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) restrict applications to droplet sizes greater than 255 μM; therefore, only droplet distributions with a mean diameter (D v0.5 ) ≥ 255 μM were selected for modeling. Fine to Medium/Coarse (F2M/C): Droplet size (D v0.5 ) = 341 μM (see AgDrift GUI screenshot in Appendix D ) 1. Regression equations were developed from SDTF field study results with ground boom equipment. 

### Orchard Air Blast 1

Equipment Not specified AgDRIFT Tier I orchard air blast model are based on regression equations developed on empirical data. Release Height Not specified AgDRIFT Tier I orchard air blast model are based on regression equations developed on empirical data.

Application Efficiency Normal: 99.85 Dense: 98.01 Sparse: 97.69 Vineyard: 99.73 AgDRIFT default/ Chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) permits all these types of applications.

### 16 of 60 Parameter Value Comments Orchard: 98.63 Wind Speed Variable AgDRIFT Tier I orchard air blast model are based on regression equations developed on empirical data. Surface Roughness Not specified AgDRIFT Tier I orchard air blast model are based on regression equations developed on empirical data. Temperature Variable AgDRIFT Tier I orchard air blast model are based on regression equations developed on empirical data. Swath Displacement Not specified AgDRIFT Tier I orchard air blast model are based on regression equations developed on empirical data. Droplet Size Not specified AgDRIFT Tier I orchard air blast model are based on regression equations developed on empirical data. Orchard Type 2 Normal, Dense, Sparse, Vineyard, and Orchard AgDRIFT default/ Chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) permits all these types of applications 1. Regression equations were developed from SDTF field study results with orchard blast equipment. 2. Normal (Stone and Pome Fruit, Vineyard): This composite orchard combines grape and apple orchards

Dense (Citrus, Tall Trees): This composite orchard combines almond, orange, grapefruit, small grapefruit (mist blower) and pecan orchards. Sparse (Young, Dormant): This composite orchard comb ines small grapefruit and dormant apple orchards. Orchard: This composite orchard combines apple, almond, orange, grapefruit, small grapefruit, pecan, and dormant apple orchards. Vineyard: This composite curve combines grape air bl ast sprayer applications and may not apply to other application equipment.



### 4.3 Hazard Inputs

Chlorpyrifos inhibits the enzyme acetylchol inesterase which leads to accumulation of acetylcholine and ultimately to neurotoxicity. In previous risk assessments, including the 2011 risk assessment, the Agency concluded that da ta on the inhibition of cholinesterase (ChE) provided the most sensitive dose- response data for use in derivi ng points of departure (POD) for all durations, routes of exposure, and lifestage s. The 2011 risk assessment included the typical scenarios used for risk assessment [acute diet ary, chronic dietary, short-term (1-30 days), intermediate-term (1 month-6 months), and long-t erm (>6 months)]. This spray drift assessment relies on the endpoint selection from the 2011, wi th refinements to account for the focus on single day exposures from spray drift. Specifi cally, revisions were ma de to provide a more appropriate match between the duration of the to xicology endpoints to th e duration of exposure. It is noted below where values varied from the 2011 risk assessment and the rationale for modifying them.

The toxicity database of laboratory animal st udies spans multiple routes of exposure (oral, dermal, and inhalation), animal species, lifestages, and durations . The database consists of studies that address different durations of exposure from a single exposure day (acute) to subchronic and chronic toxicity. The metabolism a nd pharmacokinetics of chlorpyrifos are wellcharacterized due to a variety of studies in diffe rent species and lifestage s. The studies used to complete this assessment are of high quality a nd provide information th at are appropriate for evaluating risks associated with single day expos ures which are the focus of this assessment. A comparative cholinesterase assay (CCA) provides information on comparative sensitivity in adult and juvenile rats from acute and repeated expos ures to chlorpyrifos. Th e POD for acute dietary risk was defined using the CCA study. The P OD was derived using a benchmark dose (BMD)

### 17 of 60 approach; details of the BMD analysis can be fo und in the 2011 risk assessment. This POD was also considered appropriate for children’s m outhing behavior, as desc ribed later in this document, for a single day duration of exposure and is thus used here.

Dermal exposures were evaluated in this assessm ent using a POD derived from a dermal toxicity study where sacrifices occurred at 4 and 21 days of dosing. It is not able that the results from the 4 day sacrifice are similar to those from 21 days of dosing. In addition, a single dose dermal administration study conducted in hu man volunteers (Nolan, et al, 1982) 22 

### indicates that effects can occur with only a single dermal dose. This means that the resulting risks using the 4-day study can be reasonably characterized as being representative of singl e day dermal risk estimates.

Finally, inhalation risks were eval uated in the 2011 risk assessment using the POD derived from an acute inhalation toxicity study. In the pr evious assessment the POD was a HEC (Human Equivalent Concentration) calcu lated based on a 24 hour basis, but realistic exposure durations are much shorter, so the HEC was revised us ing a 2 hour duration. This 2 hour period was selected because it both repres ented a dosing time in the stud y and the potential duration of exposure from spray drift. Note: The impact of using a 2 hour duration is discussed in more detail below, including how the exposure source is considered after the fi rst hour of application given how the drift es timates are modeled.

The endpoints and PODs used for this analysis are summarized in Table 4 . A 1x FQPA safety factor (SF) was used in all cases, except for the 10X FQPA database uncerta inty factor (UF) that was applied, to account for LOAEL to NOAEL extrapolation in the acute inhalation study because a NOAEL was not determined (LOAEL = Lowest observed adverse effect level and NOAEL = No observed adverse e ffect level). As discussed in the 2011 risk assessment, benchmark dose modeling of the acute inhalati on study results was attempted, but the doseresponse data were not amenable for this type of analysis.

Table 4. Toxicological Doses, Endpoints and Po ints of Departure for Chlorpyrifos Drift Risk Assessment Exposure Scenario Point of Departure (mg/kg/day) Study and Toxicological Effects

Acute Dietary (all populations)

[Also used in this case to represent single day Incidental Oral exposures] BMDL10 = 0.36 UFA = 10x UFH = 10x FQPA SF = 1x

Residential LOC for MOE=100 Inhibition of RBC ChE in male and female rat pups. Weight of evidence from several acute oral studies:

• CCA Study (MRID 48139301) in the rat – PND 11 males and females

22 This study was reviewed by Human Studies Revi ew Board in 2009. Materials are available at: http://www.epa.gov/osa/hsrb/jun-24-25-2009-public-meeting.htm . Additionally it should be noted that a 2008 FIFRA Scientific Advisory Panel review indicated that this study provides useful information but is not appropriate for defining PODs http://www.epa.gov/scipoly/sap/meetings/2008/september/sap0908report.pdf

.

### 18 of 60 Exposure Scenario Point of Departure (mg/kg/day) Study and Toxicological Effects

• Data on PND17 males , Moser et al.( 2006)

• Qualitative support from Timchalk et al. (2006) and Zheng et al. (2000) studies

Dermal Short- (1 – 30 days) and Intermediate-Term (1 to 6 months)

[Also used in this case to represent single day dermal exposures] NOAEL = 5 mg/kg/day

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

Residential LOC for MOE=100 Plasma and RBC ChE inhibition.

21-day dermal study (NOAEL) and 4 day probe study (LOAEL) at 10 mg/kg/day in adult rats (MRID 40972801).

Acute Inhalation

[A 2 hour HEC has been calculated which better reflects actual exposure conditions and the available dosing regimen from the study.] Inhalation LOAEL = 3.7 mg/m 3 HEC = 2.48 mg/m 3
UF A = 3x UF H = 10x FQPA UF DB = 10x (LOAEL to NOAEL extrapolation (residential)

Residential LOC for MOE=300 Lung ChE inhibition.

Special acute inhalation study (MRID 48139303). (Aerosol) [2, 4, and 6 hour sacrifice data were used to define the 2 hour HEC]



### 4.4 Exposure Inputs

The exposure aspects of this anal ysis were completed based on th e algorithms and input values specified in the recently revised (2012) Standard Operating Procedures For Residential Risk Assessment (SOPs) . These are publicly available and addre ss many broad issues pertinent to the development of risk assessments for pestic ides used in a residential environment. 23 

### These SOPs have been extensively peer reviewed and inform ation on this process is also publicly available. 24 

### The calculations in this analysis were developed by considering the variety of possible pathways and all pertinent routes of exposure that could occu r associated with spray drift. As a result of this process, two pathways were identified and used to evaluate the potential risks associated with spray drift including (1) inhalation exposures at discrete distances downwind of a treated field during application and (2) exposures from lawns adjacent to treated fields where drift

occurs.

Inhalation exposure calculations we re based on modeled air concentr ations of chlorpyrifos in a vertical plane at specified dist ances downwind from the edge of a treated field. These represent 1

23 http://www.epa.gov/pesticides/scien ce/residential-exposure-sop.html and http://www.epa.gov/pesticides/science/EPA- OPP-HED_Residential%20SOPS_Feb2012.pdf
24 http://www.epa.gov/scipoly/sap/meetings/2009/100609meeting.htm
, http://www.epa.gov/scipoly/sap/meetings/1999/092199_mtg.htm , and http://www.epa.gov/scipoly/sap/meetings/1997/090997_mtg.htm

### 19 of 60 hour time weighted average concentr ations during application and can be defined only for aerial applications. In this case these outputs were used to estimate breathing zone exposure concentrations. Specifically, these concentrations were estimated using Tier II in the AgDRIFT model (V2.01) with varied spray/application rate s. The only modifications to the Tier II inputs were altering the volatile and nonvolatile component s of the spray solution variables to account for the specific application rate s and chlorpyrifos products cons idered in this assessment. Vertical flux planes were cons idered at different distances ra nging from the edge of a treated field to 125 feet downwind of the field. This anal ysis is only possible for aerial applications because both the ground boom and airblast aspect s of AgDRIFT are empirical in nature, thus making upper tier analyses, which provide this type of output, not possible. In order to account for dilution, a dissipation rate of 25 percent per h our was used. This is protective as defined by an analysis conducted using the well-mixed box model, which is described in th e residential SOPs. Exposure concentrations were used to compare to the acute inhalation HEC presented in Table 4 to calculate risks.

The calculations for the second pa thway included in this analysis are based on the premise that chlorpyrifos residues drift away from a treated area, are deposited downwind ( e.g. , on a lawn) and, then serve as a potential source of exposur e. Once the amount of drift has been quantified, the resulting levels are considered like any pesticide intended for use on lawns. In this assessment, agricultural application rates are adjusted by th e amount of drift averaged over a 50 foot wide lawn. These lawns are considered at different distances up to 300 feet (125 reported) downwind from a treated field (closest edge to th e treated field defines the distance). In this assessment, dermal exposures were added to non-di etary incidental ingestion exposure sources to calculate total risks because the toxicological en dpoint was similar for all routes of exposure ( i.e., cholinesterase inhibition).

When risks associated with lawn pesticides are calculated, if residue da ta referred to as turf transferable residues (TTRs) are av ailable, they are used as the basis of the calcu lation. If TTRs are not available, they are estimated using an established default methodology as described in the SOPs. TTR data, generated when chlorpyrifos use on turf was allowable, are available in this case and have been used directly as prescribed in the SOPs. The chlorpyrifos TTR data were used in the 2011 risk assessment to evaluate other scenarios involving possible contact with treated turf, including de posits resulting from the mosquito adu lticide use of chlorpyrifos and its use on golf courses. The data have been summarized and used for the purposes of this assessment in a manner similar to what was done in the 2011 risk assessment.

The available TTR study (MRID 44829601) was conducte d in three states in cluding California, Indiana, and Mississippi. This study examined the residues of chlor pyrifos on turf after application of Dursban® Pro (emulsifiable c oncentrate), Dursban® 50W (wettable powder), Dursban® 2.5G (granular) and Dursban® 1F (flowabl e granular). Single applications of the test products were made to the treatment plots usi ng tractor mounted boom sprayers for the liquid applications. The liquid applicati ons were made at a nominal a pplication rate of 4 lb ai/a. 25 

### Duplicate samples were collected using the California roller techni que at the following intervals:

25 In the calculations, residue levels from this study are adjusted based on the amount of drift and the varied application rates considered in the assessment.

### 20 of 60 one day prior to the applicati on, just after the application ( 2.5 hours), and days 1, 2, 4, and 7 after application. Samples were analyzed for residues of chlorpyrifos. 26 

### 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. Average fiel d fortification recoveries (corre cted for concurrent recovery), at each of three fortification le vels were greater than 90% at all sites. Dursban® Pro, a liquid formulation, results are presented in Table 5 . The results for this formulation are presented because they represent the highest relative levels of residues resulting from the products used in this study. The chlorpyrifos dissipation half-life, at all sites, was approximately 14 hours or less.

Table 5. Chlorpyrifos (Dursban Pro EC ) TTR Data Collected Using California Roller Method

Site Target App Rate (lb ai/A) Deposition At Appl. Rate

(μg/cm 2 ) Day of Application Mean TTR

(μg/cm 2 ) TTR as % App. Rate

CA 3.80 42.60 0.124 0.29

IN 3.98 44.62 0.090 0.20

MS 3.83 42.93 0.146 0.34
average 3.87 43.38 0.120 0.28



### 4.5 Risk Assessment

As there is a wide variety of use scenarios desc ribed on chlorpyrifos labe ls, all calculations in this assessment were completed using an approach that groups currently re gistered chlorpyrifos application rates and crops into appropriate ca tegories. The use information included in this document is presented in order to provide contex t for the groupings. The a pplication rates listed for the individual groupings represent the maximum single application rate for the crops in that grouping (see Table 6 ).

Table 6. Chlorpyrifos Application Groupings Single Application Rate of Chlorpyrifos lb ai/a Example Use Site Comments

6 Citrus Use only permitted in specific counties in Arizona and California 3.5 or 4 other citrus, grass grown for seed Use permitted nationwide

2.3 Citrus Aerial application used to control psyllid, the vector for citrus greening 1 (pest present in Florida and possibly California and Texas)

2 nursery and orchard trees, tree fruit,
nuts Use permitted nationwide 1 alfalfa, asparagus, sorghum, Use permitted nationwide

26 Chlorpyrifos oxon was not measured but this would not imp act the results of this analys is because only the values immediately following application were considered in this assessment.

### 21 of 60 strawberry, and sugarbeet 1. Based on recent communications between EP A/OPP/PRD and DAS, et al. (May 17, 2012)



### In addition to these groupings, calculations we re further delineated by application method and the types of spray patterns and spray conditions used. These are based on the pre-defined options incorporated into the AgDRIFT model, and they include: 27



### • Orchard Airblast (normal, dense, spar se, and vineyard foliage/canopy levels) 28



### • Aerial [spray droplet patterns/si zes include fine to medium (Dv 0.5 

### = 255 μM), medium (Dv 0.5 

### = 294 μM), medium to coarse (Dv 0.5 

### = 341 μM), coarse to very coarse (Dv 0.5 

### = 439 μM)]

• Groundboom [low (20 in) and high (50 in) booms , fine to medium/coarse spray pattern (Dv 0.5 

### = 341 μM)]

As described in detail above, two ty pes of calculations were complete d in this analysis. All of the calculations follow the guidance contained in th e residential SOPs and the drift/deposition outputs described above. The appe ndices of this document cont ain the detailed algorithms and inputs used for this analysis, as well as the results.

4.6 Risk Reduction Options

The concept behind the development of the DRTs and the overall guidance of the PR notice for labeling related to spray drift described above is that pes ticide applicators can control drift through the use of specific equipment and applic ation parameters. These parameters include spray nozzle size, application pressure, vehi cle type and configur ation, release height, formulation choice, use of additives such as surfactants, and considering terrain as well as atmospheric conditions at the time of applicati on. Additional spray drift modeling was completed for several droplet size distributi ons to investigate the impact th at the aircraft, wind speed, swath displacement (the horizontal offset distance between the flight line and the target area), and crop canopy have on the deposition pattern of chlor pyrifos downwind of treated fields. These represent implementable means that applicat ors could potentially use to reduce drift

Tier II modeling for ground and orchard applic ations was not completed as AgDRIFT does not have the capability to refine the spray drift estim ates for these applicati on types; however, Tier II spray drift analysis can and was completed usi ng AgDRIFT for aerial applications. As a Tier II assessment tool, AgDRIFT is a parameterized mode l that can be used to investigate specific aerial application parameters. For chlorpyrifos , aerial application para meters investigated

27 Note: Orchard airblast and groundboom are only availabl e for Tier I analysis. A “m edium” droplet size (Dv 0.5 = 294 μM) is only attainable for analysis in Tier II.
28 Normal (Stone and Pome Fruit, Vineyard): This composite orchard combines grape and apple orchards

Dense (Citrus, Tall Trees): This composite orchard combines almond, orange, grapefruit, small grapefruit (mist blower) and pecan orchards. Sparse (Young, Dormant): This composite orchard comb ines small grapefruit and dormant apple orchards. Orchard: This composite orchard combines apple, almond, orange, grapefruit, small grapefruit, pecan, and dormant apple orchards. Vineyard: This composite curve combines grape air bl ast sprayer applications and may not apply to other application equipment.

### 22 of 60 included: aircraft (fixed and rotary winged), wi nd speed (10 and 5 mph), and swath displacement (default value based on droplet size see Table 3 and 100%). AgDRIFT input values for the Tier II analyses are provided in Table 7

. Table 7. Tier II AgDRIFT Input Parameters Parameter Value Comments Aerial

Equipment Air Tractor AT-401 WASP Helicopter There are no aircraft restrictions on chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591); therefore, one fixed and one rotary winged aircraft was chosen. The default airplane (fixed wing) used in the Tier I analysis was used for consistency between analyses. One of the two default Tier II options for helicopter (rotary wing) was selected by the assessor. Release Height 10 ft Chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) restrict applications to 10 ft above the crop canopy.

Wind Speed 10 mph 5 mph Chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) limit applications to time periods when the wind speed is between 3 and 10 mph. Surface Roughness 0.0075 m (0.3 in) AgDRIFT default value

Temperature 86 °F AgDRIFT default value

Swath Displacement 0.3702 and 1 (F2M) 0.3351 and 1(M) 0.2781 and 1 (M2C) 0.2489 (C) 0.2149 and 1 (C2VC) 0.2005 (VC) While an upwind swath displacement is recommended on chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) a specific displacement value is not prescrib ed. The default Tier I value was selected by the assessor for consis tency with the Tier I analysis. An alternative swath displacement of 100% was selected by the assessor to evaluate the impact of swath displacement.

Droplet Size F2M, M, M2C, C, C2VC Chlorpyrifos labels ( e.g. , EPA Reg. No. 62719-591) restrict applications to droplet sizes greater than 255 μM; therefore, only droplet distributions with a mean diameter (D v0.5 ) ≥ 255 μM were selected for modeling. These drople t sizes are consistent with the Tier I analysis.

Nonvolatile Rate 1.49 lb/a

1.35 lb/a Chlorpyrifos label EPA Reg. No. 62719-591 (59.8% other ingredients /40.2% a.i. x 1 lb ai/a = 1.49 lb/a other ingredients based on data provided on the label as shown below).

Chlorpyrifos label EPA Reg. No. 66222-19 (57.5% other ingredients /42.5% a.i. x 1 lb ai/a = 1.35 lb/a other ingredients based on data provided on the label as shown below)

### 23 of 60 Parameter Value Comments Aerial

Spray Volume 2 gal/a Minimum required spray volume Carrier Type Water Chlorpyrifos labels ( e.g. , EPA Reg. No. 66222-19) Fine to Medium (F2M): Average Droplet size (D v0.5 ) = 255 μM Medium (M): D v0.5 = 294 μM Medium to Coarse (M2C): D v0.5 = 341 μM Coarse (C) D v0.5 = 385 μM Coarse to Very Coarse (M2C): D v0.5 = 439 μM Very Coarse (VC): D v0.5 = 478 μM Other input parameters were not changed or adjusted based on standard AgDRIFT recommendation via program prompts.



### The Tier I and Tier II analysis for aerial appl ications are based on bare ground applications. A Tier III analysis for aerial appl ications to investigate the effect that a crop canopy may have on the deposition pattern downwind of a treated field following an aerial application of chlorpyrifos was contemplated. However, the use of Tier II I results are limited primarily for the following reasons: 1) canopy simulations in AgDISP are base d on theoretical calcula tions and the results have not be validated (compared to field da ta); and 2) AgDISP simulations represent canopy structures that are expected to be di fferent from chlorpyrifos use sites ( e.g. , AgDISP simulations are based on a uniformly closed canopy which is generally not expected for tree crops in an orchard setting). These limitations were di scussed with and acknowledged by the model developer, Dr. Harold Thistle with the U.S. Forest Service. 29 

### Tier III results ar e not presented in this document.

5 Results

The results of the analyses completed to evaluate the potential risks from chlorpyrifos spray drift are presented below. Section 5.1 describes the different spray dr ift modeling outputs that were calculated for the current label prescribed applic ation conditions as well as those that were calculated representing potential risk mitigation options. Section 5.2 presents the inhalation risk estimates that were calculated. Section 5.3 presents the risk estimates associated with contact of residues which potentially deposit on lawns adjoining treated fields.

29 Personal communication on May 30, 2012

### 24 of 60 5.1 Drift Estimates

The spray drift deposition curves for the Tier I analysis for aer ial applications are shown in Figure 3 . This analysis includes fine to medium [average droplet size (D v0.5 

### ) = 255 μM, which represents the current label], medium to coarse (D v0.5 

### = 341 μM) and coarse to very coarse (D v0.5 

### = 439 μM) droplet sizes. The estimated drift conc entrations over a 50’ wide lawn for various distances downwind from the tr eated field are provided in Table 8

. These estimated drift concentrations are shown for a range of chlorpyrifos applic ation rates (1 to 6 lb ai/a).

Figure 3. Tier I Spray Drift Analys is: Aerial Deposition Curves for Three Different Droplet Sizes

Table 8. Tier I Spray Drift Analysis: Average Depo sition Concentrations (lb ai/a) for a 50’ Wide Lawn Starting at Va rious Distances Downwind From a Field Treated with Chlorpyrifos Using Aerial Equipment

Application Rate (lb ai/a) Droplet Size Distance Downwind From Treated Field (feet)

0 10 25 50 75 100 125 150 200 250 300 Average Deposition Concentrations (lb ai/a) for a 50’ Wide Lawn

6 F2M 1.64 1.23 1.02 0.77 0.58 0.46 0.38 0.32 0.25 0.20 0.17 M2C 1.38 0.91 0.70 0.49 0.34 0.26 0.21 0.18 0.13 0.10 0.08 C2VC 1.23 0.71 0.50 0.31 0.22 0.17 0.13 0.11 0.08 0.06 0.05



### 4 F2M 1.10 0.82 0.68 0.51 0.38 0.30 0.25 0.22 0.16 0.13 0.11 M2C 0.92 0.60 0.46 0.32 0.22 0.17 0.14 0.12 0.08 0.07 0.05 C2VC 0.82 0.48 0.33 0.21 0.15 0.11 0.22 0.07 0.05 0.04 0.03



### 2.3 F2M 0.63 0.47 0.39 0.29 0.22 0.18 0.14 0.12 0.09 0.08 0.06 M2C 0.53 0.35 0.27 0.19 0.13 0.10 0.08 0.07 0.05 0.04 0.03 C2VC 0.47 0.27 0.19 0.12 0.08 0.06 0.05 0.04 0.03 0.02 0.02



### 2 F2M 0.55 0.41 0.34 0.26 0.19 0.15 0.13 0.11 0.08 0.07 0.06 M2C 0.46 0.30 0.23 0.16 0.11 0.09 0.07 0.06 0.04 0.03 0.03 C2VC 0.41 0.24 0.17 0.10 0.07 0.06 0.04 0.04 0.03 0.02 0.02 0 0.1 0.2 0.3 0.4 0.5 0.6

0 50 100 150 200 250 300Fraction of Applied

Distance Downwind From Treated Fields AT401, F2M, 10 mph, 37% SD AT401, M2C, 10 mph, 28% SD AT401, C2VC, 10 mph, 21% SD

### 25 of 60 1 a F2M 0.27 0.20 0.17 0.13 0.10 0.08 0.06 0.05 0.04 0.03 0.03 M2C 0.23 0.15 0.12 0.08 0.06 0.04 0.03 0.03 0.02 0.02 0.01 C2VC 0.20 0.12 0.08 0.05 0.04 0.03 0.02 0.02 0.01 0.01 0.01 Fine to Medium (F2M): Avg. Droplet size (D v0.5 ) = 255 μM, Medium to Coarse (M2C): D v0.5 = 341 μM, Coarse to Very Coarse (C2VC): D v0.5 = 439 μM The double box indicates the current aquatic buffer distance of 150 feet. a. The average deposition concentration for a 50’ wide lawn at each of the distances down wind. This is equivalent in terms of the average fraction of the ap plied that deposits over the same area [ e.g. , 0.27 lb ai/a is equivalent to a fraction applied of 0.27 (or 27% of the agricultural application rate)].



### Tier I results are presented in Figure 4 and

### 26 of 60 Table 9 for fine to medium droplet sizes fo r applications using ground boom application equipment with high and low spray booms. The resu lts suggest that potentia l spray drift exposure is higher near the field when a high boom is used as compared to a low boom; however, once several feet ( ≥ 10 ft) downwind the exposure resulting from the use of either boom is about the

same.

Figure 4. Tier I Spray Drift Analysis: Deposition Curves Resulting From the Application of Chlorpyrifos Using Ground Equipment 0 0.2 0.4 0.6 0.8

1

0 50 100 150 200 250 300Fraction of Applied



### Distance Downwind From Treated Fields High Boom Low Boom

### 27 of 60 Table 9. Tier I Spray Drift Analysis: Average Depo sition Concentrations (lb ai/a) for a 50’ Wide Lawn Starting at Va rious Distances Downwind From a Field Treated with Chlorpyrifos Using Ground Equipmen t (high and low boom options)

Application Rate (lb ai/a) Boom Height Distance Downwind From Treated Field (feet)

0 10 25 55 75 100 125 150 200 250 300 Average Deposition Concentrations (lb ai/a) for a 50’ Wide Lawn

6 High 1.63 0.11 0.08 0.05 0.04 0.04 0.03 0.03 0.02 0.02 0.02 Low 1.37 0.07 0.05 0.03 0.03 0.02 0.02 0.02 0.01 0.01 0.01


### 4 High 1.08 0.07 0.05 0.04 0.03 0.02 0.02 0.02 0.01 0.01 0.01 Low 0.91 0.04 0.03 0.02 0.02 0.02 0.01 0.01 0.01 0.01 0.01


### 2 High 0.54 0.04 0.03 0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.01 Low 0.46 0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.00 0.00 0.00


### 1 a High 0.27 0.02 0.01 0.01 0.01 0.01 0.01 0.00 0.00 0.00 0.00 Low 0.23 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Low Boom 0.508 m (20 in), High Boom 1.27 m (50 in) Fine to Medium/Coarse (F2M/C): Avg. Droplet size (D v0.5 ) = 341 μM The double box indicates the current aquatic buffer distance of 25 feet.

a. The average deposition concentration for a 50’ wide lawn at each of the distances downwind. This is equivalent in terms of the average frac tion of the applied that deposits over the same area [ e.g. , 0.27 lb ai/a is equivalent to a fraction applied of 0.27 (or 27% of the agricultural application rate)]. b. Data are reported for the 90 th percentile.



### Finally, Tier I results are presented in Figure 5 and Table 10 for fine to medium droplet sizes for applications using orchard airbla st application equipment. These results show that the highest exposure from spray drift is when chlorpyrifos ap plications are made to sparsely vegetated or dormant orchards. This is consistent with the fact that canopy density and spray interception likely correlates to potential reductions of spray drift.

Figure 5. Tier I Spray Drift Analysis: Deposition Curves Resulting from the Application of Chlorpyrifos Using Orchard Blast Equipment in Various Orchard Types 0.00 0.10 0.20 0.30 0.40 0.50 0.60

0 50 100 150 200 250 300Fraction of Applied



### Distance Downwind From Treated Fields Normal (Stone and Pome Fruit, Vineyard) Dense (Citrus, Tall Trees)

Sparse (Young, Domant)

### 28 of 60 Table 10. Tier I Spray Drift Analysis: Average Depo sition Concentrations (lb ai/a) for a 50’ Wide Lawn Starting at Variou s Distances From a Field Treated with Chlorpyrifos Using Orchard Blast Equipment in Various Orchard Types

Application Rate (lb ai/a) Crop Canopy Distance Downwind From Treated Field (feet)

0 10 25 50 75 100 125 150 200 250 300 Average Deposition Concentrations (lb ai/a) for a 50’ Wide Lawn

6 Normal 0.03 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Dense 0.44 0.16 0.06 0.03 0.04 0.03 0.02 0.02 0.01 0.01 0.01 Sparse 1.70 0.48 0.27 0.12 0.06 0.04 0.03 0.02 0.01 0.01 0.00 Vineyard 0.12 0.02 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Orchard 0.80 0.24 0.15 0.07 0.05 0.03 0.02 0.02 0.01 0.01 0.01



### 4 Normal 0.02 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Dense 0.29 0.11 0.04 0.02 0.03 0.02 0.02 0.01 0.01 0.01 0.01 Sparse 1.13 0.32 0.18 0.08 0.04 0.03 0.02 0.01 0.01 0.00 0.00 Vineyard 0.08 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Orchard 0.53 0.16 0.10 0.05 0.03 0.02 0.02 0.01 0.01 0.01 0.01



### 2 Normal 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Dense 0.15 0.05 0.02 0.01 0.01 0.01 0.01 0.01 0.00 0.00 0.00 Sparse 0.57 0.16 0.09 0.04 0.02 0.01 0.01 0.01 0.00 0.00 0.00 Vineyard 0.04 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Orchard 0.27 0.08 0.05 0.02 0.02 0.01 0.01 0.01 0.00 0.00 0.00



### 1 a Normal 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Dense 0.07 0.03 0.01 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 Sparse 0.28 0.08 0.05 0.02 0.01 0.01 0.00 0.00 0.00 0.00 0.00 Vineyard 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Orchard 0.13 0.04 0.02 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00 Normal (Stone and Pome Fruit, Vineyard): This composite orchard combines grape and apple orchards Dense (Citrus, Tall Trees): This composite orchard combines almond, orange, grapefruit, small grapefruit (mist blower) and pecan orchards. Sparse (Young, Dormant): This composite orchard comb ines small grapefruit and dormant apple orchards. Orchard: This composite orchard combines apple, almond, orange, grapefruit, small grapefruit, pecan, and dormant apple orchards. Vineyard: This composite curve combines grape air blast sprayer applications and many not apply to other application equipment. The double box indicates the current aquatic buffer distance of 50 feet. a. The average deposition concentration for a 50’ wide lawn at each of the distances down wind. This is equivalent in terms of the average fraction of the ap plied that deposits over the same area [ e.g. , 0.27 lb ai/a is equivalent to a fraction applied of 0.27 (or 27% of the agricultural application rate)].



### The spray drift deposition curves fo r the Tier II analysis for aerial chlorpyrifos applications are shown in Figure 6 for a medium droplet size (D v0.5 

### = 295 μM). Included in Appendix E are the results for fine to medium droplet size (D v0.5 

### = 255 μM), medium to coarse (D v0.5 

### = 341 μM) and coarse to very coarse (D v0.5 

### = 439 μM) droplet sizes ( Figures E.1
, E.2 and E.3 , respectively). For all the droplet size spectra analyzed, the fracti on of chlorpyrifos applie d that is expected to

### 29 of 60 be deposited over a 50’ wide lawn for various distances downwind from the treated field are provided in Table 11

. 30



### Figure 6. Tier II Spray Drift Analysis: Deposi tion Curves for a Medium Droplet Size Following Chlorpyrifos Application Using Several Different Aerial Application Configurations

Table 11. Tier II Spray Drift Analysis: Average Deposition Concentrations (lb ai/a) for a 50’ Wide Lawn Starting at Various Distances From a Field Treated with Chlorpyrifos Using Several Different Aerial Application Configurations and a Medium Droplet Size

Configuration Distance Downwind From Treated Field (feet)

0 10 25 50 75 100 125 150 200 250 300 Average Fraction of Applied Deposited on a 50’ Wide Lawn Downwind of a Treated Field 1 AT401, F2M, 10 mph, 37% SD 0.28 0.21 0.18 0.14 0.10 0.09 0.07 0.06 0.05 0.04 0.04 WASP, F2M, 10 mph, 37% SD 0.27 0.21 0.17 0.11 0.09 0.07 0.06 0.05 0.04 0.03 0.03 AT401, F2M, 5 mph, 37% SD 0.19 0.16 0.12 0.09 0.07 0.06 0.05 0.05 0.04 0.03 0.03 AT401, F2M, 10 mph, 100% SD 0.16 0.14 0.12 0.09 0.08 0.07 0.06 0.05 0.04 0.04 0.03 AT401, F2M, 5 mph, 100% SD 0.10 0.09 0.08 0.06 0.06 0.05 0.05 0.04 0.03 0.03 0.02 WASP, F2M, 5 mph, 100% SD 0.08 0.07 0.06 0.05 0.04 0.04 0.03 0.03 0.02 0.02 0.01

AT401, M, 10 mph, 37% SD 0.24 0.18 0.15 0.11 0.08 0.07 0.05 0.05 0.04 0.03 0.03 WASP, M, 10 mph, 37% SD 0.22 0.16 0.13 0.09 0.06 0.05 0.04 0.04 0.03 0.02 0.02 AT401, M, 5 mph, 37% SD 0.16 0.13 0.10 0.06 0.05 0.04 0.04 0.04 0.03 0.02 0.02 AT401, M, 10 mph, 100% SD 0.13 0.11 0.09 0.07 0.06 0.05 0.04 0.04 0.03 0.03 0.02 AT401, M, 5 mph, 100% SD 0.08 0.07 0.06 0.05 0.04 0.04 0.03 0.03 0.02 0.02 0.02 WASP, M, 5 mph, 100% SD 0.06 0.05 0.04 0.04 0.03 0.03 0.02 0.02 0.02 0.01 0.01 AT401, M2C, 10 mph, 28% SD 0.24 0.16 0.12 0.09 0.06 0.05 0.04 0.03 0.03 0.02 0.02

30 To obtain the estimated chlorpyrifos concentrations (lb ai/a), as presented for Tier I analysis, the fraction of applied should be multiplied by the range of chlorpyrifos application rates (1 to 6 lb ai/a). 0 0.1 0.2 0.3 0.4 0.5 0.6

0 50 100 150 200 250 300Fraction of Applied



### Distance Downwind From Treated Fields (feet) M, AT401, 10 mph, 37% SD M, WASP, 10 mph, 37% SD M, AT401, 5 mph, 37% SD M, AT401, 10 mph, 100% SD M, AT401, 5 mph, 100% SD M, WASP, 5 mph, 100% SD

### 30 of 60 Configuration Distance Downwind From Treated Field (feet)

0 10 25 50 75 100 125 150 200 250 300 Average Fraction of Applied Deposited on a 50’ Wide Lawn Downwind of a Treated Field 1 WASP, M2C,10 mph, 28% SD 0.21 0.14 0.11 0.07 0.05 0.04 0.03 0.03 0.02 0.02 0.01 AT401, M2C,5 mph, 28% SD 0.15 0.11 0.08 0.05 0.04 0.03 0.03 0.02 0.02 0.02 0.01 AT401, M2C,10 mph, 100% SD 0.10 0.08 0.07 0.05 0.04 0.03 0.03 0.03 0.02 0.02 0.01 AT401, M2C,5 mph, 100% SD 0.05 0.04 0.04 0.03 0.03 0.02 0.02 0.02 0.02 0.01 0.01 WASP, M2C, 5 mph, 100% SD 0.04 0.03 0.03 0.02 0.02 0.02 0.01 0.01 0.01 0.01 0.01

AT401, C, 10 mph, 25% SD 0.22 0.14 0.10 0.07 0.05 0.04 0.03 0.03 0.02 0.02 0.01 WASP, C, 10 mph, 25% SD 0.19 0.12 0.09 0.05 0.04 0.03 0.02 0.02 0.01 0.01 0.01 AT401, C2VC, 10 mph, 21% SD 0.21 0.12 0.09 0.06 0.04 0.03 0.02 0.02 0.01 0.01 0.01 WASP, C2VC, 10 mph, 21% SD 0.17 0.10 0.07 0.04 0.03 0.02 0.02 0.02 0.01 0.01 0.01 AT401, C2VC, 5 mph, 21% SD 0.12 0.08 0.05 0.03 0.02 0.02 0.02 0.01 0.01 0.01 0.01 AT401, C2VC, 10 mph, 100% SD 0.06 0.05 0.04 0.03 0.02 0.02 0.02 0.02 0.01 0.01 0.01 AT401, C2VC, 5 mph, 100% SD 0.03 0.03 0.02 0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.01 WASP, C2VC, 5 mph, 100% SD 0.02 0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.00 0.00

AT401, VC, 10 mph, 20% SD 0.20 0.11 0.07 0.05 0.03 0.02 0.02 0.02 0.01 0.01 0.01 WASP, VC, 10 mph, 20% SD 0.16 0.09 0.06 0.04 0.03 0.02 0.02 0.01 0.01 0.01 0.01 1. To obtain the estimated chlorpyrifos concentrations (lb ai/a ), as presented for Tier I analysis, the fraction of applied sho uld be multiplied by the range of chlorpyrifos application rates (1 to 6 lb ai/a). Fine to Medium (F2M): Average Droplet size (D v0.5 ) = 255 μM Medium (M): D v0.5 = 294 μM Medium to Coarse (M2C): D v0.5 = 341 μM Coarse (C) D v0.5 = 385 μM Coarse to Very Coarse (M2C): D v0.5 = 439 μM Very Coarse (VC): D v0.5 = 478 μM The double box indicates the current aquatic buffer distance of 150 feet.



### The results suggest that swath displacement a nd wind speed have the most impact, of all the parameters tested, on reducing the amount of ch lorpyrifos spray drift downwind of a treated field. A comparison of the different droplet sizes also shows that increasing the size of the spray droplet reduces the spray drift as well. This is also suppor ted by the Tier I analysis.

5.2 Risk Estimates From Inhalation Exposure

The risk estimates associated w ith potential inhalation exposures are presented in this section ( Table 12 ). Note: Detailed calculations are included in Appendix F

. The toxicological input for this calculation is a Human Equivalent Concentration (HEC) based on an acute rat inhalation study with multiple sampling times on day of dosi ng that was used to calculate a 2 hour HEC (2.48 mg/m 3 

### ). A no observed adverse effect level (NOAEL) was not determined in the rat inhalation study, as a result, the total uncertainty factor considered appropriate for identifying risks of concern is 300 ( i.e., MOEs < 300 present a risk estimate of concern).

In the 2011 risk assessment a 24 hour exposur e period was used, which was a reasonable approach given that the source of exposure was ambient air and em issions occurred over a longer period of time than would be expected for typi cal spray drift exposure situations. The HEC used

### 31 of 60 was also based on a 24 hour period. Inhalation expos ures from spray drift have instead been evaluated based using a 2 hour durat ion in order to better reflect how they would likely occur. This also required that an updated HEC based on a 2 hour exposure period be calculated as described above. The exposure considerations related to this approach are discussed below. This study was completed using sma ll aerosols (~2 microns).

Air concentrations in the breat hing zone were calculated usin g the Tier II option in AgDRIFT (V2.01). AgDRIFT provides air concen trations at specified distances downwind of a treated field in a vertical flux plane but this capability is limited only to aerial applications. These values are 1 hour time-weighted averages and have a certain degree of conservatism associated with them because in AgDRIFT the wind vector ( i.e., speed and direction) remains constant at all times and this analysis was based on a 10 mph windspeed, th e highest allowable under current chlorpyrifos labels which results in the hi ghest possible air concentrations . It also calculates air concentrations for the range of dr oplet sizes included in the partic ular spectra used as the basis for the model run. In all cases, droplets less than approximately 10 microns account for a very small percentage of the overall amount of dropl ets produced for any spectra that would be used for modeling of chlorpyrifos drift. The dichotom y between how the data used as the basis for the HEC and the airborne exposure concentrations should be considered when interpreting the associated risk estimates ( i.e. , they are conservative because only a small percentage of the airborne exposure concentration is made up of droplets which c ould reach the lung).

For further consideration relative to the application methods evalua ted, especially those that take more time to complete ( i.e., groundboom and airblast applications), wind vectors would be expected to change to some extent. In order to reflect actual anticipat ed exposures over 2 hour periods and account for expected changes in at mospheric conditions an approach to factor dilution over time was used based on the 1 hour c oncentrations as a starting point. The 1 hour values were amortized using a dilution factor of 25 percent per hour over the 2 hour exposure period. This value, especially when coupled with the premise inherent in AgDRIFT of a constant wind vector, is intende d to represent possible conditions but also be conservative ( e.g. , 20 flight passes for aerial applications which c ould take a substantial time period and a constant windspeed and vector). Values that represent a higher degree of dilution we re considered but not utilized because some atmospheric conditions could potentially impe de dilution such as atmospheric inversions or diametric changes in wind direction. However, to be thorough, the impact of conditions where more dilution would be expected was also investigated and these were found not to impact the results in a ma nner that would alter th e conclusions of the
assessment.

Finally, it is not appropriate to combine this exposure with thos e described below in Section 5.3 because the exposure conditions differ ( e.g., duration, time/location issu es), there are different uncertainties associated with each pathway, and the HEC in this case is based on lung cholinesterase inhibition using very small dropl ets (~ 2 microns) which differs from the other types of exposures.

Single day risk estimates based on the current la bel directives for managing spray drift are of concern for most scenarios at the 4 and 6 lb ai/a rates even at 125 feet from the edge of a treated field. Some scenarios are of concern at applicati on rates of 2 and 2.3 lb ai/a at 75 feet from the

### 32 of 60 edge of a treated field when using medium to coar se nozzles. If larger dr oplets are used risks are not of concern at shorter distances . At the lower application rate of 1 lb ai/a risks estimates are not of concern at the field edge for larger droplets and not of c oncern at 10 feet for medium to coarse droplets. There are possi ble techniques that applicators can use to reduce drift from treated fields. These are discussed below in Section 6 but due to a lack of information further refinements to these calculations have not been attempted.

Table 12. Inhalation Risk Estimates Associat ed With Spray Drift at Differing Distances From Edge of Treated Field

Flux Plane Distance (ft) Results Based On 2 Hr Amortized Concentration Medium/Coarse Droplets Coarse/Very Coarse Droplets ng/m3 MOE ng/m3 MOE 6.0 lb ai/ A - Citrus [CA/AZ]
0 46875 53 34375 72
10 39063 63 26563 93
25 31875 78 20313 122
50 26250 94 15625 159
75 20000 124 11250 220
100 16250 153 9375 265
125 13750 180 7813 317 4 lb ai/ A - Nursery and Orchard Trees (except apple), Tree Fruit, Tree Nuts
0 32813 76 23438 106
10 27500 90 18438 135
25 23125 107 14375 173
50 18750 132 11250 220
75 14375 173 8750 283
100 12500 198 7500 331
125 10625 233 5938 418
2.3 lb ai/ A - psyllid, the vector for citrus greening 1

0 20625 120 14375 173
10 16875 147 11250 220
25 14375 173 8750 283
50 11875 209 7500 331
75 10000 248 5625 441
100 8125 305 5000 496
125 7500 331 4375 567 2 lb ai/ A - Nursery and Orchard Trees (except apple), Tree Fruit, Tree Nuts
0 18125 137 12500 198
10 15000 165 10000 248

### 33 of 60 Flux Plane Distance (ft) Results Based On 2 Hr Amortized Concentration Medium/Coarse Droplets Coarse/Very Coarse Droplets ng/m3 MOE ng/m3 MOE
25 13125 189 8125 305
50 11250 220 6875 361
75 8750 283 5000 496
100 8125 305 4375 567
125 6875 361 3750 661 1 lb ai/ A - Alfalfa, Asparagus , Sorghum, Strawberry, Sugarbeet
0 10000 248 6875 361
10 8125 305 5000 496
25 7500 331 5000 496
50 6250 397 3750 661
75 5625 441 3125 794
100 5000 496 2500 992
125 4375 567 1875 1323
MOEs<300 would indicate a risk concern

1. Pest present in Florida and possibly California and Texas



### 5.3 Combined Risk Estimate s From Lawn Deposition Adjacent to Applications

The risk estimates associated with deposition of residues that could potentially result in exposures akin to those experienced from intenti onally treated turf are pr esented in this section ( Table 13 ). These have been calculated using the Ti er I option in the AgDRIFT model and the droplet spectra that are allowable per current chlo rpyrifos labels. All of the results for orchard airblast and groundboom results are a llowable under existing labels. Note: Cells indicating risk estimates of concern have been hi ghlighted for ease of review. Also, detailed calculations are included in Appendix G

. The results are based on the premise that if a resi dence with a 50 foot wide lot exists next to a treated field spray drift could re sult from an application such th at residues could be deposited across that lot on the lawn. Childre n could play on that contaminated turf resulting in exposure. This type of exposure has been assessed using th e residential SOPs as described above. The only difference between these calculati ons that quantify exposure due to chlorpyrifos spray drift landing on residential lawns and an evaluation of a pesticide in tended for use on lawns is how the exposure concentration is determined. The amount deposited on lawns in this approach is based on the agricultural application rate which was then adjusted for the average amount of spray drift deposition anticipated for the scenar io across the modeled lawn (50’ wide). In addition to results included in Table 13 that are based on AgDrift Ti er I, additional scenarios have been evaluated using AgDrift Tier II in cluding considering medium, coarse, and very coarse sized droplets and the impact of usi ng potential spray drift reduction measures ( Table 14 ). In all cases, exposures were considered for la wns where the nearest side of the property was

### 34 of 60 directly adjoining th e treated field (at field edge) up to 125 feet downwind of a treated field (see Figure 2 ). The toxicological points of departure for this analysis are route specific and highly refined. Dermal and non-dietary ri sk estimates were combined because the toxicity endpoint for each route of exposure is cholinesterase inhibition . The total applicable uncertainty factor is 100 so MOEs < 100 would be of concern.

The risk estimates presented in Table 13 based on AgDrift Tier I indicate that the major risk concern is from aerial applications. 31 

### Risk estimates from grou nd boom and orchard airblast applications are not of concern past 25 feet downwind from a field edge for all situations considered, even at higher applic ation rates, except fo r a couple of airblast application scenarios representing sparse orchard canopy situations. For aerial applications, risks are of concern up to 125 feet downwind from a treated field. Risks are reduced if lower application rates are considered. Also, the impact of changing nozzle types resulting in coarser sprays, which drift less, reduces risks from aerial applications.

Table 13. Risk Estimates Associated With Spray Drift Deposition Based On AgDrift Tier 1 From All Pertinent Application Methods
Application

Scenario (Rep. Crop) Appl. Rate (lb ai/A) Nozzle/ Spray Type Day (0) Highest Measured TTR (ug/cm2) MOEs At Various Distances Downwind From Treated Fields

Source Appl. Rate Day 0 Levels At Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet

Aerial

Tier I [Citrus (CA/AZ)] 6.0 Fine to Medium Pro - MS 3.83 0.146 10 13 15 20 27 34 42

Mean-All

sites 3.87 0.120 12 16 19 25 33 42 51

Medium to

Coarse Pro - MS 3.83 0.146 11 17 22 32 46 60 75

Mean-All

sites 3.87 0.120 14 21 28 40 57 74 93

Coarse to Very Coarse Pro - MS 3.83 0.146 13 22 31 50 72 93 121

Mean-All

sites 3.87 0.120 16 27 39 61 88 114 148

Tier I [Tree Fruits,

Nuts, Orchards, Nursery] 4.0 Fine to Medium Pro - MS 3.83 0.146 14 19 23 31 41 51 63

Mean-All

sites 3.87 0.120 18 23 28 38 50 63 77

Medium to

Coarse Pro - MS 3.83 0.146 17 26 34 48 70 90 113

Mean-All

sites 3.87 0.120 21 32 41 59 86 111 139

Coarse to Very Coarse Pro - MS 3.83 0.146 19 33 47 75 108 140 181

Mean-All

sites 3.87 0.120 23 40 58 92 133 172 222

Tier I [psyllid, the vector for

citrus greening (CA/FL/TX)] 2.3 Fine to Medium Pro - MS 3.83 0.146 25 33 40 53 71 89 109

Mean-All

sites 3.87 0.120 31 41 49 65 87 110 134

Medium to

Coarse Pro - MS 3.83 0.146 30 45 59 84 121 156 196

Mean-All

sites 3.87 0.120 36 55 72 103 149 192 241

31 Note that aggregate exposures that also consider other sources of possible chlorpyrifos exposure ( e.g., food and water) have not been incorporated into these risk esti mates presented herein. These will be addressed in the registration review risk asse ssment for chlorpyrifos where all other pe rtinent aggregate exposure estimates will be presented and discussed.

### 35 of 60 Application

Scenario (Rep. Crop) Appl. Rate (lb ai/A) Nozzle/ Spray Type Day (0) Highest Measured TTR (ug/cm2) MOEs At Various Distances Downwind From Treated Fields

Source Appl. Rate Day 0 Levels At Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet

Coarse to Very Coarse Pro - MS 3.83 0.146 33 57 82 130 188 243 315

Mean-All

sites 3.87 0.120 41 70 101 159 230 298 387

Tier I [Tree Fruits,

Nuts, Orchards, Nursery] 2 Fine to Medium Pro - MS 3.83 0.146 29 38 46 61 82 103 125

Mean-All

sites 3.87 0.120 35 47 57 75 100 126 154

Medium to

Coarse Pro - MS 3.83 0.146 34 52 67 97 139 180 226

Mean-All

sites 3.87 0.120 42 64 83 119 171 221 278

Coarse to Very Coarse Pro - MS 3.83 0.146 38 66 94 149 216 279 362
Mean-All

sites 3.87 0.120 47 81 116 183 265 343 445

Tier I Alfalfa, Asparagus. Sorghum, Strawberry, Sugarbeet 1 Fine to Medium Pro - MS 3.83 0.146 57 76 92 122 163 205 250

Mean-All

sites 3.87 0.120 70 94 113 150 201 252 307

Medium to

Coarse Pro - MS 3.83 0.146 68 104 135 193 279 360 452

Mean-All

sites 3.87 0.120 83 127 166 237 342 442 555

Coarse to Very Coarse Pro - MS 3.83 0.146 76 132 188 298 431 558 724

Mean-All

sites 3.87 0.120 94 162 232 367 530 686 890

Airblast

Tier I [Citrus (CA/AZ) ] 6 Normal Pro - MS 3.83 0.146 485 1350 1907 3023 4168 5223 6445
Mean-All

sites 3.87 0.120 596 1659 2344 3715 5123 6419 7921

Dense Pro - MS 3.83 0.146 36 97 264 531 399 531 685
Mean-All

sites 3.87 0.120 44 119 324 653 491 653 841

Sparse Pro - MS 3.83 0.146 9 33 57 132 247 387 589
Mean-All

sites 3.87 0.120 11 40 70 163 303 476 724

Vineyard Pro - MS 3.83 0.146 135 672 1149 2218 3387 4500 5810
Mean-All

sites 3.87 0.120 166 825 1413 2725 4163 5531 7140

Tier I [Citrus] 3.5 Normal Pro - MS 3.83 0.146 832 2314 3270 5182 7146 8954 11049
Mean-All

sites 3.87 0.120 1022 2843 4019 6369 8782 11004 13579

Dense Pro - MS 3.83 0.146 61 166 452 911 685 911 1174
Mean-All

sites 3.87 0.120 75 203 555 1119 842 1119 1442

Sparse Pro - MS 3.83 0.146 16 56 98 227 423 664 1009
Mean-All

sites 3.87 0.120 19 69 120 279 520 816 1240

Vineyard Pro - MS 3.83 0.146 232 1151 1970 3802 5807 7715 9960
Mean-All

sites 3.87 0.120 285 1415 2422 4672 7136 9482 12241

Tier I [Tree Fruits/Nuts/O

rchards, Nursery] 2 Normal Pro - MS 3.83 0.146 1456 4049 5722 9069 12505 15669 19336

Mean-All

sites 3.87 0.120 1789 4976 7033 11145 15368 19257 23763

Dense Pro - MS 3.83 0.146 107 290 791 1594 1198 1594 2054
Mean-All

sites 3.87 0.120 131 356 972 1958 1473 1958 2524

Sparse Pro - MS 3.83 0.146 28 98 172 397 740 1162 1766
Mean-All

sites 3.87 0.120 34 120 211 488 910 1428 2171

### 36 of 60 Application

Scenario (Rep. Crop) Appl. Rate (lb ai/A) Nozzle/ Spray Type Day (0) Highest Measured TTR (ug/cm2) MOEs At Various Distances Downwind From Treated Fields

Source Appl. Rate Day 0 Levels At Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet

Vineyard Pro - MS 3.83 0.146 406 2015 3448 6653 10162 13501 17430
Mean-All

sites 3.87 0.120 499 2476 4238 8176 12488 16593 21421

Tier I [Christmas

Trees, Conifer, Deciduous Nursery, Grape] 1 Normal Pro - MS 3.83 0.146 2912 8098 11445 18137 25010 31339 38671

Mean-All

sites 3.87 0.120 3578 9952 14065 22290 30737 38515 47526

Dense Pro - MS 3.83 0.146 213 580 1581 3187 2397 3187 4108
Mean-All

sites 3.87 0.120 262 712 1943 3917 2946 3917 5048

Sparse Pro - MS 3.83 0.146 55 196 343 794 1481 2325 3533
Mean-All

sites 3.87 0.120 68 240 422 975 1820 2857 4342

Vineyard Pro - MS 3.83 0.146 811 4029 6896 13306 20323 27002 34860
Mean-All

sites 3.87 0.120 997 4952 8475 16352 24976 33185 42843

Groundboom

Tier I [Grape (E of

Cont. Divide)] 6 Low Boom/Fine to Med/Coarse Pro - MS 3.83 0.146 11 235 327 467 587 687 794

Mean-All

sites 3.87 0.120 14 289 402 574 722 844 976

High Boom/Fine to Med/Coarse Pro - MS 3.83 0.146 10 143 201 292 373 441 515

Mean-All

sites 3.87 0.120 12 176 247 359 458 542 633

Tier I [Orchard Floor] 4 Low Boom/Fine to Med/Coarse Pro - MS 3.83 0.146 17 353 490 701 881 1030 1191

Mean-All

sites 3.87 0.120 21 434 602 861 1083 1266 1464

High Boom/Fine to Med/Coarse Pro - MS 3.83 0.146 14 215 301 439 560 662 773

Mean-All

sites 3.87 0.120 18 264 370 539 688 813 950

Tier I [Fig, Peanut,

Mint, Strawberry, etc.] 2 Low Boom/Fine to Med/Coarse Pro - MS 3.83 0.146 34 706 980 1401 1762 2061 2382

Mean-All

sites 3.87 0.120 42 867 1205 1722 2166 2533 2927

High Boom/Fine to Med/Coarse Pro - MS 3.83 0.146 29 429 603 877 1119 1323 1546

Mean-All

sites 3.87 0.120 35 527 741 1078 1375 1626 1900

Tier I [Brussel Sprouts, Cauliflower,

Onion, Soybean, Wheat] 1 Low Boom/Fine to Med/Coarse Pro - MS 3.83 0.146 69 1412 1961 2802 3524 4121 4764

Mean-All

sites 3.87 0.120 84 1735 2410 3444 4331 5065 5854

High Boom/Fine to Med/Coarse Pro - MS 3.83 0.146 58 858 1206 1755 2238 2646 3093

Mean-All

sites 3.87 0.120 71 1055 1482 2156 2751 3252 3801

MOEs<100 indicate a risk estimate of concern

### 37 of 60 Additional results were calculated using AgDrift Tier II in order to evaluate risks associated with a variety of droplet spectra and to evaluate the impact of potentia l spray drift redu ction measures ( Table 14 ). This type of analysis is only feasible for aerial applications due to limitations with the AgDRIFT model. Section 4.6 above describes the types of a pplication parameters that were considered in detail. Some of the factors are believed to be readily implementable under actual field conditions as described in Section 3.2 ( e.g. , use of different droplet spectra). Others have been evaluated as well to identify how sensitive the results would be relative to changes in such parameters even though they may be less viable as mitigation measures because they are harder to routinely implement ( e.g. , swath width and windspeed at time of application).

To summarize, the possible mitigation m easures that were considered include:

• use of a helicopter (WASP) rather than fixed wing aircraft (AT 401),

• varied swath displacement (100% of the width of the aircraft shift inward from the field edge rather than the standard values for each droplet spectra – e.g. , 34% for medium) ,

• use of coarser droplets than the label i ndicates, specific size ranges are noted, and

• a reduction in maximum allowable wind speed during application from 10 to 5 mph.

These were developed in the cont ext of the draft PR Notice guida nce for spray drift labeling and the DRTs discussed in Section 3.2 above.

It is clear that applicators can utilize measures that will be effective for reducing spray drift levels and that the methods will reduce risk estimates depending upon the situation. Altered nozzle size appears to be an effective approach for reducing risks compared to the current label that could be readily implementable.

Table 14. Risk Estimates Associated With Spray Drift Deposition Based On AgDrift Tier II From Aerial Application

Application Scenario App Rate (lb ai/A) Nozzle Configuration Day (0) Highest Measured TTR MOEs At Various Distances Do wnwind From Treated Fields

Source Appl. Rate (ug/cm2) At Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet

Tier II (AT 401/10 mph/34%SD)

6.0 Medium Pro - MS 3.87 0.146 10 14 18 24 32 40 48 Tier II (AT 401/5 mph/34%SD) Medium Pro - MS 3.87 0.146 16 20 26 40 51 59 67 Tier II (AT 401/10 mph/100%SD) Medium Pro - MS 3.87 0.146 21 24 28 36 45 53 60 Tier II (AT 401/5 mph/100%SD) Medium Pro - MS 3.87 0.146 33 40 46 56 64 71 80 Tier II (Wasp/10 mph/34% SD) Medium Pro - MS 3.87 0.146 11 15 19 29 40 49 60 Tier II (Wasp/10 mph/100% SD) Medium Pro - MS 3.87 0.146 24 30 35 46 56 65 75 Tier II (Wasp/5 mph/34% SD) Medium Pro - MS 3.87 0.146 18 26 35 52 65 75 100 Tier II (Wasp/5 mph/100% SD) Medium Pro - MS 3.87 0.146 45 52 59 70 82 95 110

Tier II (AT 401/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 12 19 25 38 53 68 84

Tier II (Wasp/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 14 22 30 49 69 88 110

Tier II (AT 401/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 13 24 35 57 81 106 136

### 38 of 60 Application Scenario App Rate (lb ai/A) Nozzle Configuration Day (0) Highest Measured TTR MOEs At Various Distances Do wnwind From Treated Fields

Source Appl. Rate (ug/cm2) At Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet

Tier II (Wasp/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 17 31 45 73 104 136 175

Tier II (AT 401/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 11 17 22 31 44 55 68
Tier II (AT 401/5 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 18 25 34 56 74 86 101
Tier II (AT 401/10 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 27 32 39 52 65 76 89
Tier II (AT 401/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 48 59 68 82 97 110 126
Tier II (Wasp/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 13 19 25 40 57 71 87
Tier II (Wasp/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 65 77 87 109 135 160 189
Tier II (AT 401/10 mph/21%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 13 22 31 48 68 86 109
Tier II (AT 401/5 mph/21%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 22 34 49 84 114 136 167
Tier II (AT 401/10 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 45 53 63 84 107 127 151
Tier II (AT 401/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 78 93 109 134 164 192 222
Tier II (Wasp/10 mph/21%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 15 27 38 63 88 113 145
Tier II (Wasp/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 114 135 156 199 248 295 350 Tier II (AT 401/10 mph/34%SD)

4.0 Medium Pro - MS 3.87 0.146 15 21 26 36 48 60 73 Tier II (AT 401/5 mph/34%SD) Medium Pro - MS 3.87 0.146 24 30 39 60 77 89 100 Tier II (AT 401/10 mph/100%SD) Medium Pro - MS 3.87 0.146 31 36 42 55 68 79 90 Tier II (AT 401/5 mph/100%SD) Medium Pro - MS 3.87 0.146 50 60 69 84 97 107 120 Tier II (Wasp/10 mph/34% SD) Medium Pro - MS 3.87 0.146 17 23 29 44 60 74 91 Tier II (Wasp/10 mph/100% SD) Medium Pro - MS 3.87 0.146 36 44 53 68 84 98 112 Tier II (Wasp/5 mph/34% SD) Medium Pro - MS 3.87 0.146 27 40 53 78 97 112 150 Tier II (Wasp/5 mph/100% SD) Medium Pro - MS 3.87 0.146 68 79 88 105 123 142 165

Tier II (AT 401/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 18 28 38 56 80 101 126

Tier II (Wasp/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 21 33 45 73 103 132 165

Tier II (AT 401/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 20 36 53 86 122 159 204

Tier II (Wasp/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 25 46 67 110 156 205 263

Tier II (AT 401/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 17 25 33 46 65 83 102
Tier II (AT 401/5 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 27 37 50 85 111 129 151
Tier II (AT 401/10 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 41 48 58 78 98 114 134
Tier II (AT 401/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 72 89 102 123 145 165 189
Tier II (Wasp/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 19 28 37 60 86 106 131
Tier II (Wasp/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 98 115 130 164 203 240 284
Tier II (AT 401/10 mph/21%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 19 32 46 72 102 129 163
Tier II (AT 401/5 mph/21%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 33 51 73 126 170 204 250
Tier II (AT 401/10 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 67 80 95 126 160 190 226
Tier II (AT 401/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 117 139 163 200 246 288 332
Tier II (Wasp/10 mph/21%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 23 40 57 94 132 170 218
Tier II (Wasp/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 171 203 233 298 371 442 524 Tier II (AT 401/10 mph/34%SD)

2.3 Medium Pro - MS 3.87 0.146 29 39 47 63 85 106 128

Tier II (AT 401/5 mph/34%SD) Medium Pro - MS 3.87 0.146 43 55 72 107 135 155 176

Tier II (AT 401/10 mph/100%SD) Medium Pro - MS 3.87 0.146 54 62 73 95 118 137 157

Tier II (AT 401/5 mph/100%SD) Medium Pro - MS 3.87 0.146 87 105 121 146 168 185 208

Tier II (Wasp/10 mph/34% SD) Medium Pro - MS 3.87 0.146 31 42 53 79 107 130 159

### 39 of 60 Application Scenario App Rate (lb ai/A) Nozzle Configuration Day (0) Highest Measured TTR MOEs At Various Distances Do wnwind From Treated Fields

Source Appl. Rate (ug/cm2) At Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet

Tier II (Wasp/10 mph/100% SD) Medium Pro - MS 3.87 0.146 63 77 92 119 146 170 195

Tier II (Wasp/5 mph/34% SD) Medium Pro - MS 3.87 0.146 50 73 97 138 170 196 230

Tier II (Wasp/5 mph/100% SD) Medium Pro - MS 3.87 0.146 118 137 153 183 215 247 287

Tier II (AT 401/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 31 49 66 98 139 176 219

Tier II (Wasp/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 36 58 78 127 180 230 288

Tier II (AT 401/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 35 62 92 150 212 277 355

Tier II (Wasp/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 43 80 116 191 271 356 457

Tier II (AT 401/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 29 44 57 80 114 144 178

Tier II (AT 401/5 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 47 64 87 147 192 224 263

Tier II (AT 401/10 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 72 84 101 136 170 199 233

Tier II (AT 401/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 126 154 178 214 253 288 328

Tier II (Wasp/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 33 49 65 104 149 185 228

Tier II (Wasp/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 171 200 227 284 353 418 493

Tier II (AT 401/10 mph/21%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 33 56 80 125 177 224 283

Tier II (AT 401/5 mph/21%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 57 89 127 219 296 354 435

Tier II (AT 401/10 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 116 138 166 219 278 330 393

Tier II (AT 401/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 203 242 284 348 428 501 578

Tier II (Wasp/10 mph/21%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 39 70 98 163 230 295 378

Tier II (Wasp/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 298 353 406 519 646 769 912

Tier II (AT 401/10 mph/34%SD)

2 Medium Pro - MS 3.87 0.146 33 45 55 73 98 122 147

Tier II (AT 401/5 mph/34%SD) Medium Pro - MS 3.87 0.146 50 63 82 123 155 179 202

Tier II (AT 401/10 mph/100%SD) Medium Pro - MS 3.87 0.146 62 71 84 109 136 158 181

Tier II (AT 401/5 mph/100%SD) Medium Pro - MS 3.87 0.146 100 121 139 168 193 213 239

Tier II (Wasp/10 mph/34% SD) Medium Pro - MS 3.87 0.146 36 48 60 91 123 150 183

Tier II (Wasp/10 mph/100% SD) Medium Pro - MS 3.87 0.146 72 89 106 137 168 196 225

Tier II (Wasp/5 mph/34% SD) Medium Pro - MS 3.87 0.146 58 84 111 159 195 226 264

Tier II (Wasp/5 mph/100% SD) Medium Pro - MS 3.87 0.146 135 157 176 211 247 284 330

Tier II (AT 401/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 36 57 76 113 160 203 251

Tier II (Wasp/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 41 67 90 146 207 264 331

Tier II (AT 401/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 40 71 106 172 243 318 409

Tier II (Wasp/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 50 93 134 220 312 409 525
Tier II (AT 401/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 33 50 65 92 131 166 204

Tier II (AT 401/5 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 54 74 101 169 221 258 302

Tier II (AT 401/10 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 82 97 116 156 196 229 267

Tier II (AT 401/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 144 177 205 246 291 331 378

Tier II (Wasp/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 38 57 74 119 172 213 262

Tier II (Wasp/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 196 230 261 327 406 481 567

Tier II (AT 401/10 mph/28%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 38 65 92 143 203 258 326

Tier II (AT 401/5 mph/28%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 65 102 146 252 341 407 500

Tier II (AT 401/10 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 134 159 190 252 320 380 452

Tier II (AT 401/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 233 279 326 401 492 576 665

Tier II (Wasp/10 mph/28%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 45 80 113 188 264 340 435

### 40 of 60 Application Scenario App Rate (lb ai/A) Nozzle Configuration Day (0) Highest Measured TTR MOEs At Various Distances Do wnwind From Treated Fields

Source Appl. Rate (ug/cm2) At Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet

Tier II (Wasp/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 342 406 467 597 743 884 1049

Tier II (AT 401/10 mph/34%SD)

1 Medium Pro - MS 3.87 0.146 66 89 109 145 196 243 295

Tier II (AT 401/5 mph/34%SD) Medium Pro - MS 3.87 0.146 100 126 165 246 311 358 404

Tier II (AT 401/10 mph/100%SD) Medium Pro - MS 3.87 0.146 124 143 167 218 272 316 362

Tier II (AT 401/5 mph/100%SD) Medium Pro - MS 3.87 0.146 201 242 278 335 387 427 478

Tier II (Wasp/10 mph/34% SD) Medium Pro - MS 3.87 0.146 71 97 121 182 246 300 367

Tier II (Wasp/10 mph/100% SD) Medium Pro - MS 3.87 0.146 145 177 211 274 335 392 450

Tier II (Wasp/5 mph/34% SD) Medium Pro - MS 3.87 0.146 115 168 223 318 390 452 529

Tier II (Wasp/5 mph/100% SD) Medium Pro - MS 3.87 0.146 271 314 353 422 494 567 659

Tier II (AT 401/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 71 114 153 225 320 406 503

Tier II (Wasp/10 mph/25%SD) Coarse Pro - MS 3.87 0.146 83 133 180 293 413 528 662

Tier II (AT 401/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 80 142 212 344 487 637 818

Tier II (Wasp/10 mph/20%SD) Very Coarse Pro - MS 3.87 0.146 99 185 267 440 623 818 1051
Tier II (AT 401/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 66 101 131 185 262 332 408

Tier II (AT 401/5 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 107 148 201 338 442 515 605

Tier II (AT 401/10 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 165 194 232 312 392 457 535

Tier II (AT 401/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 289 354 409 493 581 661 755

Tier II (Wasp/10 mph/28%SD) Medium to Coarse Pro - MS 3.87 0.146 75 114 149 239 343 425 525

Tier II (Wasp/5 mph/100%SD) Medium to Coarse Pro - MS 3.87 0.146 393 459 522 654 812 961 1134

Tier II (AT 401/10 mph/28%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 75 129 184 287 406 516 652

Tier II (AT 401/5 mph/28%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 131 204 292 503 682 814 1000

Tier II (AT 401/10 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 267 318 381 505 640 759 905

Tier II (AT 401/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 466 558 653 801 984 1152 1329

Tier II (Wasp/10 mph/28%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 91 160 226 376 529 679 870

Tier II (Wasp/5 mph/100%SD) Coarse to Very Coarse Pro - MS 3.87 0.146 685 812 934 1194 1485 1769 2098

MOEs<100 indicate a risk estimate of concern



### 6 Issues For Consideration

The available incident data and limited monitoring data included in the risk assessment indicated spray drift can be of concern. The analysis in this document supplements the findings in the 2011 HHRA by using modeling approaches which allow fo r a broader consideration of the potential impacts on risk estimates due to varied applica tion scenarios. This analysis was developed by coupling established methods for estimating spray drift and residential ex posures. As such, the caveats and concerns that can be associated w ith those techniques also apply herein.

Even given this premise, there ar e a significant number of issues th at should be considered in the interpretation of the results including:

• The risk estimates calculated are based on the premise that spray drift occurs in a manner similar to that predicted and that an exposed person is at the locations and exhibits the behaviors mimicked in the risk assessment. Th ese activities are believed to be plausible.

### 41 of 60 Examples could include homebound individu als at a location downwind and lawns adjacent to fields that could be contaminated followed by children playing on them.

• The analysis and resulting recommendations ha ve been developed in a manner consistent with guidance in the draft PR Notice fo r spray drift labeling and the DRTs. The evaluation of possible risk mitigation approach es considered information developed in a manner consistent with this context. One exam ple may be to develop droplet spectra data that evaluates the impact of adjuvants on the spray pattern ( e.g., sticking and drift reduction agents).

• Spray drift values are based on the general appl ication of the Tier I output values from AgDRIFT and the subsequent higher tier an alyses that were completed. There are uncertainties associated with all of thes e approaches which have been discussed extensively during the activities of the SDTF and the developm ent of these models. All of the associated uncertainties apply to the results of this analysis (please refer to the FIFRA SAP reviews cited above). Ther e are additional analyses wh ich could be completed in order to elicit how sensitive spray dr ift levels may be to such changes ( e.g. , evaluate impact of alternative aircraft, evaluate no zzle placement, impacts of surface roughness). It should also be noted that in the drift analyses completed in the assessment, wind vectors were moving from treated areas to the downwind area of the field 100 percent of the time and in most analyses (except some mitigation option analyses that considered lower values) windspeed was set to 10 m ph which would maximize spray drift levels under the model conditions.

• The residential aspects of the calculation are ba sed on the recently revised SOPs that have undergone an extensive review process as cite d above. Associated with each calculation there is a degree of uncertainty which is described in detail in the SOPs themselves. A couple of issues should be noted in the interpre tation of the calculated risks. In this case a TTR study for chlorpyrifos using multiple formulations in three different locations was available. The formulation that provided the highest relative TTR was used for estimating risks (Dursban Pro – which is a commonly us ed liquid formulation). TTR levels in the cited study varied by about a factor of two depending upon location and the type of formulation. Also, the TTR half-life in all cases was less than 1 day and in most cases less than 12 hours. Using this formulation, as compared with granules as an example, more closely mimics the exposures that w ould be expected from liquid spray drift.

• Aerial application is used on a small percenta ge of the crops for which chlorpyrifos is labeled, with the percent crop treated for most crops on the order of 1 to 2 percent. However, when acreage is treated using airc raft, it can account for a substantial number of the total applications for that crop on an annual basis ( e.g., alfalfa, almonds, apples, asparagus).

• Single day risk estimates were calculated by comparing calculated exposures to PODs defined based on animal studies that are of high quality and a ppropriate for that purpose. For many pesticides, defining PODs for si ngle day non-dietary exposure scenarios is difficult, but for chlorpyrifos the data exists . For the inhalation exposure pathway, a state

### 42 of 60 of the art study that defined lung cholinestera se as the endpoint was used to establish the POD ( i.e., the HEC). For non-dietary ingestion a single day POD, the same used for defining the aPAD in the 2011 HHRA, was used. It was established based on the results of a single dose CCA (comparative cholin esterase assay) study that measured cholinesterase inhibition. Fina lly, 4 day sacrifice data in th e same 21 day dermal toxicity study used to define the dermal POD in the 2011 HHRA also supports using the existing POD also as the basis of a the single day a ssessment approach. This characterization of the dermal study is also supported by a hum an volunteer dermal study (Nolan et al, 1992). Finally, the dichotomy between the nominal droplet size used to generate the HEC and the airborne exposure concentration shoul d be considered in any evaluation of the related risk estimates ( i.e. , they are conservative because only a small percentage of the airborne exposure concentration is made up of droplets which c ould reach the lung).

7 Conclusions and Recommendations

Because it can be demonstrated that spray drift occurs even if applica tions are compliant with labels, spray drift has been further examined to quantify potential risk estimates associated with exposure to chlorpyrifos downwind of a treated field. The approach es used as the basis for all calculations in this document ha ve been thoroughly vetted through a public peer review process. In most cases, the findings indicate risks are a concern adjacent to trea ted fields and aerial applications, out of all application types consider ed, have the highest associated risk estimates. There are several actions which could be taken that would resu lt in lower risk estimates. The impacts have been examined quantitativel y where feasible. In some cases, differing combinations of possible mitigation options were also considered. These include:

• Reduce maximum application rates to those needed to achieve desired efficacy as appropriate.

• Require that buffer distances, similar to thos e already in place to address aquatic risk concerns, also be required to alleviate poten tial human health risks in situations where deemed appropriate. This would entail alte ring labels to expand the applicability and scope of the existing buffer distances for a ll areas where drift c ould result in human
exposure.

• Implement drift reduction tec hnologies and approaches consis tent with DRTs that can alleviate risks including:

o require larger droplets be used to a lter spray patterns and reduce drift ( e.g., perhaps by requiring larger nozzle sizes by specifying a droplet size distribution ( i.e. , D v0.5 ) 

### on the label))

o require larger swath displacement from field edge

• Other possible approaches, consistent with th e spirit of those used recently to manage potential risks for fumigants, may also be appropriate such as:

o drift management plans for applicators

### 43 of 60 o specialized training for applicators on drift management issues

o use of buffer credit system consistent with the concept of DRTs, supported by appropriate data

o place restrictions around sens itive areas such as schools

o encourage use of technology to manage drift such as GPS for pilots

• Restrict aerial applications based on risk findings and available mitigation options.

Data to confirm the efficacy of any DRT measur es implemented to reduce the risk estimates associated with spray drift from chlorpyrifos should be developed.

### 44 of 60 

# Appendix A- Summary of Label Use Patterns

Table A1: Summary of Chlorpyrifos Agricultural Uses

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

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

1.5 Soil Ground Band (postharvest) (CA only) (Midwest and Pacific Northwest states – Amvac) Beets (Table and Sugar Grown for Seed) 2 Soil Ground (preplant, at-plant) (24c)

Brassica Vegetable (Bok Choy, Broccoli, Broccoli Raab, Brussels Sprout, Cabbage, Cauliflower, Chinese Broccoli, Collards, Kale, and Kohlrabi) 1.0 Foliar Ground, Aerial
2.25 Soil Ground Spreader or Splitter, T-Band (at-plant) 2.4 Soil Band, Broadcast, Sidedress, & Injection (at plant, established plant, postplant) Cauliflower 1.2 oz/1000 ft row Soil Ground, Soil Injected (preplant, atplant, postplant) Broccoli, broccoli raab, etc. 1.3 - 1.4 oz/1000 ft row Soil Ground, Soil Injected (preplant, atplant, postplant) Broccoli, Brussels sprout, cabbage 1.4 oz/1000 ft row Ground (at-plant) (24c)

Cauliflower 1.3 oz/1000 ft of row Ground (at-plant) (24c) Bok choy, broccoli raab, Chinese broccoli 2.11 Soil Ground (at-plant) (24c)

Carrot (Grown for Seed) 1 Aerial, Groundboom (24c) Citrus Fruit 6 (AZ and CA) Aerial, Airblast, Groundboom, High Volume Spray (dilute), Low Volume (concentrate) Ground Sprayer, Broadcast, 4 (States other than AZ and CA) Aerial, Airblast, Groundboom, High volume Spray (dilute), Low Volume Ground (concentrate) Sprayer 2.5 (24c) Trunk Drench, Hand Held Sprayer
2.0 Soil Broadcast, Chemigation Orchard Floors, Fertilizer Treatment; Mechanical Mixer 1.0 Soil Ground Orchard Floors Soil Ground, Chemigation Orchard Floors, Fertilizer Treatment, Trunk Drench, Soil Broadcast, Directed Spray, Granule Applicator, Mechanical Mixer, Power

### 45 of 60 Sprayer, Backpack Mist Citrus orchard floors 1.0 Soil Ground orchard floors Soil Ground, chemigation orchard floors Clover (Grown for Seed) 2.0 (24c) Soil Ground (preplant), Broadcast Foliar Ground (postplant) Corn (Field, Grown for Seed and Sweet) 3.0 Soil Incorporation (preplant) 2.0 Soil In-Furrow, T-Banding, Granule Applicator (at plant; post plant) 1.5 Aerial, Broadcast, Chemigation (postemergence) 1.0 Foliar Aerial (postplant);Soil Band/In-Furrow Ground (preplant, atplant, preemergence); Broadcast, Chemigation Field, sweet 0.06 lb/lb seed (24c) Commercial seed treatment Field, sweet 0.5 Foliar Ground, Aerial, Chemigation (preplant, at plant, postemergence) (24c) Cotton 2.0 (24c) Aerial, Broadcast, Power Sprayer Cotton 1.0 Aerial, Foliar, Broadcast, Chemigation, Groundboom Cotton 012 lb/lb seed Commercial Seed Treatment Cranberry 1.5 Aerial, Chemigation, Groundboom, Broadcast Sprayer Fig (CA only) 2.0 Soil Incorporation (dormant) Ginseng 2.0 Soil Broadcast (preplant incorporation, postemergence) Grapes 2.0 Soil Surface, Broadcast Ground Spray (dormant, delayed dormant) (24c, East of Continental Divide) postharvest (24c) 1.0 Soil Drench (prebloom), Soil Broadcast, Ground, Hand-Held Sprayer (base, vine, Soil) (24c) Legume Vegetables (Succulent or Dried, Except for Soybeans) 1.0 Soil Incorporation, T-Band, Ground (preplant, at-plant) Mint (Peppermint and Spearmint) 2.0 Chemigation, Groundboom

Onion (Dry Bulb) 1.0 Groundboom, Tractor Drawn Spreader, Handgun Peanut 2.0 Soil Ground (at-plant) Foliar Ground (postplant, band rescue) Soil Ground (preplant) Peppers 1.0 Broadcast, Foliar, Groundboom (24c) Pineapple (Non-bearing) 2.0 Broadcast, Foliar Ground (postplant) (24c) Radish 3.0 Soil Ground Spreader or Splitter (at-plant in-furrow) Radish (Grown for Seed) 1.0 Foliar Ground (24c) Rutabaga 8.8 Soil T-Band (at plant) 2.0 Soil T-Band, Incorporation (preplant; atplant)

### 46 of 60 Sorghum 

### 3.0 Soil Band, Incorporation (at plant) 1.0 Aerial, Chemigation, Groundboom, Soil TBand, Incorporation, Broadcast (at plant, postemergence, Foliar) 0.0024 lb/lb seed Commercial Seed Treatment Soybean 2.0 Soil T-Band, Incorporate, Ground (at-plant, postplant) 1.0 Aerial, Broadcast, Foliar Groundboom, Chemigation (preemergence, at-plant, postemergence) Strawberry 2.0 Groundboom, Soil Incorporation, Broadcast (preplant spring, Foliar) 1.0 Broadcast, Directed Spray (Foliar), Soil Incorporation (preplant); Foliar Ground (postharvest) Sugarbeet 2.0 Soil Incorporation, Band, (preplant, at plant, postplant) 1.0 Aerial, Chemigation, Groundboom,Broadcast, Soil Band, Incorporation, (atplant, preplant, postemergence) 0.5 Soil band, Incorporation (preplant, at plant) Sugarbeet (Grown for Seed) 2.0 Soil incorporation, (preplant, at-plant) (24c)Aerial, Chemigation, Groundboom Sunflower 2.0 Soil Ground (at-plant) Soil Ground (preplant)Aerial, Groundboom 1.5 Foliar Ground, Aerial Broadcast (postemergence) Sweet Potato 2.0 Soil preplant incorporation Tobacco 2.0 Soil preplant incorporation Almonds 4.0 Chemigation, Soil Broadcast, Foliar, Mound Treatment 3.0 lb/100 gal Trunk Drench, Foliar 2.0 Foliar Ground, Aerial, Broadcast, Ground, High Volume Dilute and Low Volume Concentrate Sprays (dormant/delayed dormant)
Almond orchard floor 4.0 Soil Ground orchard floor, Soil Broadcast, chemigation, individual Mound Treatment
Filbert 2.0 Foliar Ground, Aerial, Broadcast, Ground, High Volume Dilute and Low Volume Concentrate Sprays (dormant/delayed dormant)
Pecan 4.0 Chemigation, Soil Broadcast, Foliar

2.0 Foliar Ground, Aerial, Broadcast, Ground, High Volume Dilute and Low Volume Concentrate Sprays (dormant/delayed dormant)

### 47 of 60 1.0 Foliar Ground, Aerial, Broadcast, Ground, High Volume Dilute and Low Volume Concentrate Spray (dormant/delayed dormant) Pecan orchard floor 2.0 Soil Ground, chemigation orchard floors

Walnut 4.0 Chemigation, Soil Broadcast, Foliar

2.0 Foliar Ground, Aerial, Broadcast, Ground, High Volume Dilute and Low Volume Concentrate Sprays (dormant/delayed dormant) 

### 1.0 Foliar Ground, Aerial, Broadcast, Ground, High Volume Dilute and Low Volume Concentrate Sprays Apple 3.0 Ground High Volume Dilute Spray (dormant, delayed dormant) 2.0 Ground High Volume Dilute & Low Volume Concentrate Spray (dormant/delayed dormant), Broadcast 1.5 lb/100 gal Trunk Spray Low Volume Handgun, Shielded Spray equipment Cherry-sour 1.5 Foliar Ground, Aerial Cherry 2.0 Foliar Ground, Aerial (dormant, delayed dormant) 3 lb/100 gal Ground trunk Spray (Foliar, postharvest) Nectarine, Peach 2.0 Ground High Volume Dilute & Low Volume Concentrate Spray, (dormant/delayed dormant) 3 lb/100 gal Ground trunk Spray or preplant dip Pear 3.0 Ground High Volume Dilute Spray (dormant, delayed dormant) 2.0 Ground airblast speed Sprayer (postharvest); Ground High Volume Dilute & Low Volume Concentrate Spray ( dormant/delayed dormant) Plum/prune 3.0 Ground High Volume Dilute & Low Volume Concentrate Spray (dormant, delayed dormant) 3 lb/100 gal Trunk Drench, Foliar Pumpkin 0.0625 lb/lb seed (24c) Commercial Seed Treatment, preplant Triticale 0.0024 lb/lb seed Commercial Seed Treatment Turnip 2.25-2.4 Soil Ground spreader or splitter ; Broadcast, Directed Spray, Soil band, Incorporation, (preplant, at-plant, postplant) 1.4 oz/1000 ft row Soil Ground (preplant, at-plant, postplant) Wheat 

### 4.0 (24c) Soil Incorporation, Foliar 1.0 Aerial, Broadcast, chemigation 0.5 Aerial, Chemigation, Groundboom, Broadcast, Foliar

### 48 of 60 0.0024 Commercial seed treatment



### Table A2: Summary of Chlorpyrifos Non-Agricultural Uses

Crop or Target Maximum (Single) Application 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 0.0066 (lb ai/ ear tag) Pliers (spring, summer) Christmas Trees (Nurseries and Plantations, Stumps) 1.0 Foliar Ground nurseries & plantations Foliar Ground plantations; Broadcast, Aerial (Helicopter) 3 lb/100 gal Stump treatment, Drench
Golf Course Turf 4.0 Spot treatment 1.0 Belly Grinder, Low Pressure Handwand, Push Type Spreader, Tractor Drawn Spreader, Turfgun; Soil Broadcast, Mound Treatment, Grass Seed (Perennial Crops) 1.0 Foliar, Ground, Aerial Greenhouse and Nursery Production (Bedding Plants, Containerized Ornamentals, Cut Flowers, Flowering Hanging Baskets, Pine Seedling Transplant, Potted Flowers, Ornamentals, Trees and Shrubs) 4.0 Soil Ground (preplant) field grown nursery stock 

### 3.0 High Volume Dilute Spray, Ground (dormant, delayed dormant) 1.0 

### High Volume Dilute Spray, Ground (dormant, delayed dormant), Low Volume Concentrate Spray, trunk Drench, stump treatment, Foliar, preplant incorporation, Broadcast (Power Sprayer, Hand Held), 1.0 Submerge Soil (containerized (potted) or balled & burlapped nursery stock) 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 Treatments, Manufacturing Sites, Power Utilities, Railroad Box Cars, Railroad Equipment, Road Medians, Ship Holds, Sod Farms, Telecommunications, 1.0 Aerial (ultra Low Volume), Belly Grinder, Groundboom, Push Type Spreader, Tractor Drawn Spreader, Soil Broadcast, band,treatment, Mound Treatment 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

### 49 of 60 Warehouse Sites) Ornamentals (Cut Flowers, Industrial Buildings/Plant Sites Perimeter 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, Broadcast, preharvest 4.0 Groundboom, Preplant Incorporation

3.0 High Volume Dilute Ground Sprayer (dormant, delayed dormant) 2.0 

### Broadcast, Hand Held Sprayer, Power Sprayer 0.16 (lb ai/gallon) Backpack Sprayer, Handgun, High Pressure Handwand, Low Pressure Handwand 0.020 (lb ai/gallon) Drench/Dip Poultry Litter 3.0 Bedding/Litter Treatment; Sprayer Roach Control Bait Stations 0.00026 (lb ai/bait station) Hand

Sewer Manhole Walls 0.30 lb/manhole Airlee Spray Equipment Delivered thru a 6 ft. Spray Wand Trees (Cottonwood and Poplar Trees Grown for Pulp, Conifer, Deciduous, Grown in Nurseries and Greenhouses) 2.0 Foliar Ground, Aerial, (dormant/delayed dormant) (24c)

Turfgrass (Sod or Seed) 4.0 Soil surface, Spot Treatment,

1.0 Tractor Drawn Spreader, Soil Broadcast treatment, Sprayer Wood Products (Fence Posts, Industrial Sites, Landscape Timbers, Logs, Manufacturing, Pallets, Processed Wood, Right of Way, Railroad Ties, Utility Poles, Wooden Containers) 16.65 lb/10,000 sq. ft. Belly Grinder, Push Type Spreader, wood Surface Treatment, Brush, Sprayer

### 50 of 60 

# Appendix B - Lorsban 75WP Label Excerpt

Spray Drift Management Do not allow spray to drift from the application site and contact people, structures people occupy at any time and the associated property, parks and r ecreation areas, non-targe t crops, aquatic and wetland sites, woodlands, pastures, rangelands, or animals.

Avoiding spray drift at the applica tion site is the responsibility of the applicator. The interaction of many equipment and weather-re lated factors determine the potential for spray drift. The applicator is responsible for c onsidering all of these factors wh en making the decision to apply this product.

Observe the following precautions when spraying Lorsban 75WG adjacent to permanent bodies of water such as rivers, natural ponds, lakes, streams, reservoirs, marshes, estuaries, and commercial fish ponds.

The following treatment setbacks or buffer zones must be utilized for applications around the above-listed aquatic areas with th e following application equipment:

Application Method Required Setback (Buffer Zone) (feet) ground boom 25 chemigation 25 orchard airblast 50 aerial (fixed wing or helicopter) 150

Making applications when wind is blowing away fr om sensitive areas is the most effective way to reduce the potential for adverse effects.

The following spray drift best management practi ces are recommended to avoid off-target drift movement from applications.

Aerial Application • The boom width must not exceed 75% of the wingspan or 90% of the rotor blade. • Nozzles must always point backward, paralle l with the air stream, and never be pointed downward more than 45 degrees. • Nozzles must produce a medium or coarse r droplet size (255 to 340 microns volume median diameter) per ASABE Standard 572 under application c onditions. Airspeed, pressure, and nozzle angle can all effect dr oplet size. See manufacturer's catalog or USDA/NAAA Applicator's Guide fo r spray size quality ratings. • Applications must not be made at a height greater than 10 feet above the top of the target plants unless a greater he ight is required for aircraft safety. Making applications at the lowest height that is safe reduces exposure of dropl ets to evaporation and wind.

### 51 of 60 • Use upwind swath displacement and apply only when wind speed is 3 to 10 mph as measured by an anemometer. Do not apply product when wind speed exceeds 10 mph. • If application includes a no-sp ray zone, do not release spray at a height greater than 10 feet above the ground or crop canopy.

Where states have more stringent re gulations, they must be observed.

The applicator should be familiar with and take into account the information covered in the Aerial Drift Reduction Advisory.

Aerial Drift Reduction Advisory This section is advisory in nature a nd does not supercede the mandatory label requirements.

Information on Droplet Size: The most effective way to reduce drift potential is to apply large droplets. The best drift management strategy is to apply the largest droplets that provide sufficient coverage and control. Applying larger droplets reduces drift potential, but will not prevent adverse effects from dr ift if applications are made improperly, or under unfavorable environmental conditions (see Wind, Temperature and Humidity, and Temp erature Inversions).

Controlling Droplet Size: • Volume - Use high flow rate nozzles to apply the highest practical spray volume. Nozzles with higher rated flows produce larger droplets. • Pressure - Do not exceed the nozzle manu facturer's recommended pressures. For many nozzle types, lower pressure produces larger droplets. When higher flow rates are needed, use higher flow rate nozzles in stead of increasing pressure. • Number of nozzles - Use the minimum nu mber of nozzles that provide uniform
coverage. • Nozzle orientation - Orienting nozzles so th at the spray is rel eased parallel to the airstream produces larger droplets than ot her orientations and is the recommended practice. Significant deflection from horizontal will reduce droplet size and increase drift potential. • Nozzle type - Use a nozzle type that is de signed for the intended application. With most nozzle types, narrower spray angles produce la rger droplets. Consid er using low-drift nozzles. Solid stream nozzles or iented straight back produce the largest droplets and the lowest drift.

Boom Length: For some use patterns, reducing the eff ective boom length to le ss than 3/4 of the wingspan or rotor length may further re duce drift without re ducing swath width.

Application Height: Applications should not be made at a height greater than 10 feet above the top of the target plants unless a greater height is required for aircraft sa fety. Making applications at the lowest height that is safe reduces exposure of dr oplets to evaporation and wind.

Swath Adjustment: When applications are made with a crosswind, the swath will be displaced downwind. Therefore, on the up and downwind e dges of the field, the applicator should

### 52 of 60 compensate for this displacement by adjusting the path of the aircraft upwind. Swath adjustment distance should increase, with increasing drift poten tial (higher wind, sma ller drops, etc.).

Wind: Drift potential is lowest between wind speeds of 2 to 10 mph. However, many factors, including droplet size and equipment type, de termine drift potential at any given speed. Application should be avoided below 2 mph due to variable wind direction and 'high inversion potential. Note: Local terrain can influence wind patterns. Every applicator should be familiar with local wind patterns and how they affect spray drift.

Temperature and Humidity: When making applications in low relative humidity, set up equipment to produce larger drople ts to compensate for evaporati on. Droplet evaporation is most severe when conditions are both hot and dry.

Temperature Inversions: Applications should not occur duri ng a temperature i nversion because drift potential is high. Temperature inversions restrict vertical air mixing, which causes small suspended droplets to remain in a concentrat ed cloud. This cloud can move in unpredictable directions due to the light vari able winds common during inversi ons. Temperature inversions are characterized by increasing temperatures with altitude and are common on nights with limited cloud cover and light to no wind. They begin to form as the sun sets and often continue into the morning. Their presence can be indicated by gr ound fog; however, if fog is not present, inversions can also be identified by the movement of smoke from a ground source or an aircraft smoke generator. Smoke that layers and moves laterally in a concentr ated cloud (under low wind conditions) indicates an inversion, while smoke that moves upward and rapidly dissipates indicates good vertical air mixing.

Sensitive Areas: The pesticide should only be applied wh en the potential for drift to adjacent sensitive areas ( e.g., residential areas, bodies of water, known habitat for threatened or endangered species, nontarget crops) is minimal ( e.g., when wind is blowing away from the sensitive areas).

Ground Boom Application The following mandatory spray drift best manage ment practices are required to reduce the likelihood of off-target drift move ment from ground applications.

• Choose only nozzles and pressures that produc e a medium or coarse droplet size (255 to 400 microns volume median diameter), per ASABE Standard 572. See manufacturer's catalog or USDA/NAAA Applicator's Guide for spray size quality ratings. • Apply with nozzle height no more than 4 feet above the ground or crop canopy. • Do not apply product when wind speed exceeds 10 mph as measured by an
anemometer.

Orchard Airblast Application The following mandatory spray drift best manage ment practices are required to reduce the likelihood of off-target drift moveme nt from airblast applications.

• Nozzles must be directed so spra y is not projected above the canopies.

### 53 of 60 • Apply only when wind speed is 3 to 10 mph at the application site as measured by an anemometer outside of the orch ard/vineyard on the upwind side. • Outward pointing nozzles must be shut off when turning corners at row ends.

The applicator should take into account the fo llowing best management practices to reduce offsite spray drift. This section is advisory a nd does not supersede mandato ry label requirements.

• Number of nozzles, nozzle orientation and spra y volume, air speed and wind direction are key factors in adjusting airblast sp ray delivery to match the heig ht and density of the crop canopy. Airblast equipment should be adjusted to pr ovide uniform coverage while minimizing the amount of spray movement over-the-top or completely through the crop canopy. • High air volumes deliver spray more effi ciently than air at high speed. Reducing forward travel speed decreases the air speed ne cessary to deliver the spray to the top of the crop canopy. • Use air guides along with the number and orie ntation of spray nozzles to achieve the desired spray coverage a nd directional control.

• The following steps should be taken to minimi ze drift and the amount of non-target spray: • Orient nozzles and adjust air speed/volume/ direction to force the spray through the crop canopy but not allow drift past the canopy. • Shut off spray delivery when passi ng gaps in crop canopy within rows. • Spray the outside rows of orchards from out side in, directing the spray into the orchard and shutting off nozzles on the side of the sprayer away from the orchard.

• When treating smaller trees, vines or bushes, shut off top nozzles to minimize over-the-top spray movement.

### 54 of 60 

# Appendix C- Summary of Use Information

Chlorpyrifos usage data on all crops were compile d from a private marketing research database. For the years 2006-2010, the following information wa s queried at the crop level: pounds of active ingredient (a.i.) applied, total area treate d (includes multiple applications to the same field), base area treated (the area treated at least once), cr op area grown, percen t of crop treated, average a.i. single application rate, the average nu mber of applications pe r year (row crops only). Averages were calculated for each variable over th e five years of data. To calculate the average number of applications per year for the specia lty crops, the total area tr eated was divided by the base area treated. When possible, a comparison was made to the releva nt data that were available from the USDA National Agricultural St atistics Service (NASS) pesticide use reports. For the following crops: beans, cucumbers, dry b eans, hazelnuts, peas, peppers, plums/prunes, pumpkins, sorghum, and squash, the data are cons idered less robust because the values are based on a limited sample size (this is defined as a total sample size of <50 across 5 years), and the data could not be verified in NASS. While the low sample size may simply be a function of low use, sample size is also an indication of reliability and should be cons idered when using the data.

In addition to estimating the average application rate for chlorpyrifos, a rate distribution was generated to estimate an upper bound application rate for each crop. The data were generated using the a.i. Rate Range database variable (set from 0-10 pounds applie d per application and at a rate interval of 0.25 pounds a.i. applied per application) along with the total acres treated database variable. These variables are part of the search functions available in the software provided along with the proprieta ry market database. To calcula te the upper bound rate, the total area treated reported at each rate interval was divided by the cumulative total area treated across all intervals. A running total was included to show the cumula tive percentile at each rate increment and the rate associated with the 90 th 

### percent was reported as the upper bound rate. The upper bound rate in this analysis is the rate at which 90% (or as close to 90% as possible) of the acres treated with chlorpyrifos are treated at or below. The values obtained using this process, related to the overall use of chlorpyrifos, are provided in an accompanying spreadsheet to this document denoted as D399483-Appendix C.

The key information, excerpted from a sepa rate memorandum, which details how ground applications play a role in ch lorpyrifos use (Grube, 2012) is included below for informational
purposes.

### 55 of 60 Table 1: Ground Applications of Chlorpyrifos to Agricultural Crops 2006- 2010 excluding Seed Treatments and Incorporated Applications

%of Total Applications Maximum Rate Observed Applied by %of Total Average Lbs for Ground Applications
Ground Crop Acreage AI Year Applied by Average Application Rate (rounded up) When 90 th percentile is Treated by Ground for Ground lower it is shown in
Crop Ground Applications parentheses
Alfalfa 69 2 320,000 0

. 6 1.0 Almonds 86 20 380,000 1.9 (2

. 0) 4.0 Apples 95 59 370,000 1.5 (2

. 0) 2

. 8 Asparagu s 76 29 10

, 000 (1.0) 1.5
Beans (Snap) 99 2,000 0.5 1.0 Broccoli 100 53 100,000 1.4 (2.1) 2.3 Cabbage 100 14 10,000 1.1 (1.5) 2.3 Cauliflower 99 40 15

, 000 1.1 (1.5) 2

. 3 Cherries 98 36 80,000 1.5 (2

. 0) 3.0 Com 19 0 200,000 0

. 9 (1

. 5) 3.0
Cotton 32 150,000 0.8 1.0 Dry BeanslPeas 37 0 5,000 0

. 5 (0.5) 0.8 Grapefruit 98 22 50

, 000 1.9 3 Grapes, Raisin 100 8 50,000 1.9 (2

. 0) 2

. 2 Grapes, Table 100 51 140,000 2

. 7 4 Grapes

, Wine 100 9 120,000 2 (2.0) 4.0 Hazelnuts 68 8 4,000 1.4 2 Lemons 96 37 90

, 000 3

. 6 6 Onions 100 45 70,000 0

. 9 (1.1) 2.8 Oranges 93 22 600,000 2

. 6 6 Peaches 95 26 50,000 1.3 (2

. 0) 3.0
Peanuts 13 20,000 1.6 2
Pears 97 17 20

, 000 1.8 2 Peas (Fresh) 100 1

, 000 1 (1.0) 1.4 Pecans 85 24 200,000 0

. 9 (1.0) 3.4 Peppers 93 2 2,000 0.8 1.5 PlumsIPrunes 100 11 25,000 1.8 2 Potatoes 82 0 1,000 0

. 8 I Pumpkins 100 1 2,000 1 (1.1) 1.2 Sorghum 47 0 6,000 0.5 0.8 Soybeans 82 5 3,000,000 0

. 4 (0.8) 1.1 Squash 99 2 800 (1.5) 2

. 0
Strawberries 100 28 15,000 (1.0) 2

. 0 Sugar Beets 38 4 40,000 0

. 7 (1

. 0) 2.0
Sunflowers 20 15,000 0.5 (0.5) 0.6 Sweet Com 57 7 70,000 1.1 (2

. 0) 4.0 Tobacco 83 11 80,000 2.1 (2.1) 5

. 0 Walnuts 94 43 320,000 1.8 (2.0) 4

. 0 Wheat,

' Spring 56 70,000 0

. 3 (0.5) 1.0
Wheat, Winter 69 2 290,000 0.4 (0

. 8) 1.0

### 56 of 60 Table 2. Incorporated Ground Applications of Chlorpyrifos 2006-2010

Maximum Rate
Observed for

% of Total Incorporated Applications % of Total Crop Average Lbs AI Averagc Applications (rounded

Incorporated Acreage With Year Applied Application Rate up)When 90 th percentile Incorporated by Incorpor ated for Incorporated is lower it is shown in
Crop Treatments Applications Applications parentheses

Com 65 800,000 1.0 (1.4) 2

. 0 Cotton 5 0 15
, 000 0.4 1.0 Dry Beans/Peas 45 0 5
, 000 0

. 5 0.5 Peanuts 85 6 140,000 1.7 2.0 Potatoes 10 0 < 500 1.1 1.5 Sorghum 13 0 3
, 000 0.8 0

. 8 Soybeans 0 40,000 0.6 1.2 Sugar Beets 50 5 80,000 1.0 (1.0) 2

. 0 Tobacco 17 2 13,000 1.6 (2.1) 5

. 0
The applications reported in this table were those for which th e application method clearly indicated incorporation. This level of detail about application method was not av ailable for fruits and vegetables so some of the ground applications for those crops may hav e incorporated as well as some of the ground applications for field crops not listed here

. Source : Private market research data, 2006- 2010

.

### 57 of 60 

# Appendix D- Model Screenshots

### 58 of 60 

# Appendix E - Results of Drift Modeling

Figure E.1. Tier II Spray Drift Analysis: Depositi on Curves for a Fine to Medium Droplet Size Following Chlorpyrifos Application Using Several Different Aerial Application Configurations

Figure E.2. Tier II Spray Drift Analysis: Deposi tion Curves for a Medium to Coarse Droplet Size Following Chlorpyrifos App lication Using Several Different Aerial Application Configurations 0 0.1 0.2 0.3 0.4 0.5 0.6

0 50 100 150 200 250 300Fraction of Applied



### Distance Downwind From Treated Fields (feet) F2M, AT401, 10 mph, 37% SD F2M, WASP, 10 mph, 37% SD F2M, AT401, 5 mph, 37% SD F2M, AT401, 10 mph, 100% SD F2M, AT401, 5 mph, 100% SD F2M, WASP, 5 mph, 100% SD



### 0 0.1 0.2 0.3 0.4 0.5 0.6

0 50 100 150 200 250 300Fraction of Applied



### Distance Downwind From Treated Fields (feet) M2C, AT401, 10 mph, 28% SD M2C, WASP, 10 mph, 28% SD M2C, AT401, 5 mph, 28% SD M2C, AT401, 10 mph, 100% SD M2C, AT401, 5 mph, 100% SD M2C, WASP, 5 mph, 100% SD

### 59 of 60 Figure E.3. Tier II Spray Drift Analysis: Depositi on Curves for a Coarse to Very Coarse Droplet Size Following Chlorpyrifos App lication Using Several Different Aerial Application Configurations

Detailed results and calculations are provided in an attached supplem ental spreadsheet as Appendix E. 0 0.1 0.2 0.3 0.4 0.5 0.6

0 50 100 150 200 250 300Fraction of Applied



### Distance Downwind From Treated Fields (feet) C2VC, AT401, 10 mph, 21% SD C2VC, WASP, 10 mph, 21% SD C2VC, AT401, 5 mph, 21% SD C2VC, AT401, 10 mph, 100% SD C2VC, AT401, 5 mph, 100% SD C2VC, WASP, 5 mph, 100% SD

### 60 of 60 

# Appendix F- Inhalation Risk Calculations

This appendix is an accompanying spreadsheet to this document.

### 61 of 61 

# Appendix G- Risk Calculations From Deposited Residues on Lawns

This appendix is an accompanying spreadsheet to this document.