OFFICE OF
CHEMICAL SAFETY AND
POLLUTION PREVENTION UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D.C., 20460



### PC Code : 059101

DP Barcode: 424487

December 23, 2014

MEMORANDUM

SUBJECT: Chlorpyrifos: Updated Drinking Water Assessment for Registration Review

TO: Joel Wolf, Chemical Review Manager Tom Myers, Team Leader Kevin Costello, Branch Chief Risk Management and Implementation Branch 2 Pesticide Re-Evaluation Division (7508P)

THROUGH: Dana Spatz, Chief

Environmental Risk Branch 3 Environmental Fate and Effects Division (7507P)

FROM: Rochelle F. H. Bohaty, Ph.D., Chemist

Environmental Risk Branch 3 Environmental Fate and Effects Division (7507P)

PEER REVIEW: James Hetrick, Ph.D., Senior Science Advisor

Environmental Risk Branch 3 Environmental Fate and Effects Division (7507P)

This document provides an update to the registration review drinking water assessment (DWA) for chlorpyrifos. A preliminary DWA was completed in 2011 1 

### and posted to the docket for public comment. Since this assessment was completed and in response to public comment, several additional analyses were completed focusing on: 1) clarifying labeled uses, 2) evaluating volatility and spray drift, 3) revising aquatic modeling input values, 4) comparing aquatic modeling and monitoring data, 5) summarizing the effects of drinking water treatment, and 6) updating model simulations using current exposure tools. The first five topics are discussed in the Additional Analyses section of this assessment or are attached ( APPENDIX 1 : Registered Use Clarification; APPENDIX 2 : Spray Drift Considerations; APPENDIX

3 : Volatility Considerations) to this assessme nt. The new model runs are presented in the Updated Modeling Simulation section of this document. The additional analyses did not change the exposure assessment conclusions previously reported in the preliminary DWA.

1 Bohaty, R. Revised Chlorpyrifos Preliminary Registration Review Drinking Water Assessment, June 20, 2011, PC Code: 059101; DP Barcode: 368388, 389480

### 2 ABSTRACT

A national screening level drinking water assessment was completed for the registration review of chlorpyrifos, with focus on the agricultural uses. The primary drinking water residue of concern is chlorpyrifos-oxon, the predominant chlorpyrifos transformation product formed during drinking water treatment ( e.g. , chlorination). To illustrate a range of estimated drinking water concentrations (EDWC), two maximum label rate application scenarios were sele cted to represent high and low end exposures, i.e., tart cherries at 5 applications totaling 14.5 pounds per acre per year, and bulb onions at a single application of 1 pound per acre per year, respectively. The application of chlorpyrifos to tart cherries

resulted in concentrations that exceeded the drin king water level of comparison (DWLOC); whereas, chlorpyrifos applications to bulb onions result in concentrations below the DWLOC. Concentrations in groundwater are not expected to exceed the DWLOC.

To investigate whether other chlorpyrifos application scenarios may result in concentrations that exceed the DWLOC, a screen of all available surface water modeling scenarios was completed considering three different application dates and a single application at several different application rates that ranged from one to six pounds. This analysis showed that even with only one application, several chlorpyrifos uses may exceed the DWLOC at rates lower than maximum labeled rates (both single as well as yearly), including an application rate of one pound per acre per year. The analysis also showed that the DWLOC exceedances are not expected to be uniformly distributed across the country.

Further analysis was conducted to look at the spatial distribution of EDWCs at a regional level, as well as by using a drinking water intake watershed approac h. This exercise demonstrated that chlorpyrifos applications will result in variable drinking water e xposures that are highly localized and that the highest exposures generally occur in small hydrologic regions where there is a high percent cropped area on which chlorpyrifos use could occur.

Finally, EDWCs were compared to monitoring data. This analysis showed that when modeling scenarios are parameterized to reflect reported use and EDWCs are adjusted to reflect percent cropped area, the EDWCs are within an order of magnitude of the measur ed concentrations reported in the monitoring data. Therefore, although there are uncertainties associated with the model input parameters for which conservative assumptions were made ( e.g. , one aerobic aquatic metabolism half-life value multiplied by the uncertainty factor of three, stable hydrolysis, 100% of the cropped watershed is treated on the same day, and use of the Index Reservoir as the receiving waterbody), these assumptions do not appear to lead to an overly conservative estimate of exposure. In addition, evaluation of the monitoring data further illustrates that exposures are highly localized. Additional work can be done to examine EDWCs on a regional and/or watershed scale to pinpoint community drinking water systems where exposure to chlorpyrifos-oxon as a result of chlorpyrifos applications may pose an exposure concern.

RESULTS SUMMARY

EDWCs are provided for chlorpyrifos and chlorpyrifos-oxon. Chlorpyrifos EDWCs were multiplied by 0.9541 (molecular weight correction factor) and 100% (maximum conversion during water purification)to generate chlorpyrifos-oxon EDWCs. Essentially, the concentration of chlorpyrifos and chlorpyrifosoxon are the same. A 100% conversion factor for the oxidation of chlorpyrifos to chlorpyrifos-oxon was used as an approximation based on empirical bench scale laboratory data that indicate chlorpyrifos rapidly oxidizes to form chlorpyrifos-oxon almost quantitatively during typical water treatment (chlorination). 2

2 Duirk, S. E.; Collette, T. W.; Degradation of Chlorpyrifos in Aqueous Chlorine Solutions: Pathways, Kinetics, and Modeling. Environ. Sci. Technol. , 2006, 40(2) , 546-550.

### 3 There are limited data available on the removal efficiency of chlorpyrifos prior to oxidation or the removal efficiency of chlorpyrifos-oxon during the drinking water treatment process. Based on empirical data showing that more than 75 percent of community water systems use chlorination to disinfect drinking water in the United States 3 

### , the assumption of exposure to chlorpyrifos-oxon equivalent to 100% conversion of chlorpyrifos is not considered overly co nservative. It is possible that some drinking water treatment procedures, such as granular activated carbon filtration and water softening (increased rate of chlorpyrifos-oxon hydrolysis at pH > 9) could reduce the amount of chlorpyrifos-oxon in finished drinking water; however, these treatment methods are not typical practices across the country for surface

water.

While there is the potential to have both chlorpyrifos and chlorpyrifos-oxon present in finished drinking water, limited (or no) information is available to readily quantify how much of each form remains following treatment. In the absence of available inform ation, all the chlorpyrifos that enters a drinking water treatment facility is assumed to be c onverted to chlorpyrifos-oxon during treatment.

Although chlorpyrifos-oxon has a hydrolysis half-life of 5 days, the drinking water treatment simulation half-life for chlorpyrifos-oxon is approximately 12 days. 4,5,6 

### Therefore, once chlorpyrifos-oxon forms during treatment, little transformation is expected to occur before consumption (during drinking water distribution). There is a wide range of treatment processes and sequences of treatment processes employed at community water systems across the country and there are limited data available on a community water system specific basis to assess the removal or transformation of chlorpyrifos during treatment. These processes are not specifically designed to remove pesticides and pesticide transformation products including chlorpyrifos and chlorpyrifos-oxon. In general, drinking water treatment processes, with the exception of activated carbon, 7 

### have been shown to have little impact on removal of pesticide residues. Additional discussion of drinking water treatment can be found in the Drinking Water

Treatment section of this DWA or in the preliminary DWA.

National Screen

The 2011 preliminary DWA, as well as the additional analyses completed as part of this assessment, indicate that exposure to chlorpyrifos-oxon in drinking water derived from surface water may pose an exposure concern. Since a large number of chlorpyrifos uses were identified in the preliminary DWA as triggering a concern, a bounding estimate of exposu re was completed using a screening level national assessment approach. This was done to determine which currently registered uses could result in exposure to chlorpyrifos-oxon in drinking water that exceed the DWLOC.

Use of chlorpyrifos on tart cherries is expected to result in the highest EDWC. EDWCs for chlorpyrifos and chlorpyrifos-oxon 8 

### are reported below for Tier I groundwater and Tier II surface water model

3 Community Water System Survey 2006; U.S. Environmental Protection Agency, Washington, DC 20460 May

2009 (survey data)

4 Tunink, A. Chlorpyrifos-oxon: Determination of hydrolysis as a function of pH, 2010 (MRID 48355201; acceptable)

5 Wu, J.; Laird, D. A. Abiotic Transformation of Chlorp yrifos to Chlorpyrifos Oxon in Chlorinated Water. Environ.

Toxcol.Chem.

, 2003 , 22(2), 261-264.

6 Tierney, D. P.; Christensen, B. R.; Culpepper, V. C. Chlorine Degradation of Six Organophosphate Insecticides and Four Oxons in Drinking Water Matrix. Submitted by Syngenta Crop Protection, Inc. 2001

. 7 Progress Report on Estimating Pesticide Concentratio ns in Drinking Water and Assessing Water Treatment Effects on Pesticide Removal and Tr ansformation: A Consultation. FIFRA Scientific Advisory Panel Meeting, September 29, 2000; SAP Report No. 2001-02 February 12, 2011.

8 Chlorpyrifos EDWCs were multiplied by 0.9541 (molecular weight correction factor) and 100% (maximum conversion during water purification) to generate chlo rpyrifos-oxon EDWCs. Additional details on the potential

### 4 simulations. Because chlorpyrifos is used on a number of agricultural crops, as well as turf, a drinking water intake percent cropped area (PCA) adjustment factor of 1 was used. 9,10 

### While the model input

values 11 

### have been updated since the preliminar y assessment, the results presented in Table 1 are similar to those previously reported.

Table 1. Estimated Drinking Water Concentrations Resulting from the Use of Chlorpyrifos

Residue Surface Water Groundwater

1-in- 10 Year

Peak

Concentration

μ g/L 21

- day Average

Concentration

μ g/L 1-in- 10 Year Annual Average

Concentration

μ g/L 30 Year Annual Average

Concentration

μ g/L SCI

- GROW Tier

I Concentration

μ g/L a

Michigan Tart Cherries

Chlorpyrifos 129 83.8 39.2 29.7 0.16

Chlorpyrifosoxon 123 80.0 37.4 28.3 0.15

Georgia Bulb Onion

Chlorpyrifos 6.2 3.1 1.2 0.8 0.01

Chlorpyrifosoxon 5.9 3.0 1.1 0.8 0.01

a. SCI-GROW resulted in higher EDWCs than PRZM-GW simulations.



### In order to better define the extent to which other chlorpyrifos use scenarios may result in an exposure concern, the Health Effects Division de veloped a 21-day average DWLOC of 3.9 μ g/L for chlorpyrifosoxon 12 

### that could be compared to model output values. Uncertainties in this approach include potential temporal aspects of relative concentrations from day to day on AChE inhibition, geospatial distribution of exposure as a result of variability in use, environmental factors, and drinking water treatment processes.

Previous risk assessments 13 

### suggest that typical upper bound application rates for chlorpyrifos are similar to the maximum single application rates for a wide range of crops; however, often the number of typical applications per year is lower than the maximum num ber of applications currently permitted on product labels ( i.e. , summarized in Master Use Summary Document ). Considering this information, a screening

impacts on drinking water treatment on chlorpyrifos and chlorpyrifos-oxon see the Additional Analyses section on Drinking Water Treatment.

9 U.S. Environmental Protection Agency Brady, D. Guidance on Development and Use of Community Water System Drinking Water Intake Percent Cropped Area Adjustment Factors for Use in Drinking Water Exposure Assessments: 2014 Updated, September 12, 2014.

10 U.S. Environmental Protection Agency, Bohaty, R., Carleton, J., Crk, T., Echeverria, M., Ruhman, M., Thawley, M., Thurman, N., Villanueva, P., White, K., Development of Community Water System Drinking Water Intake Percent Cropped Area Adjustment Factors for Use in Drinking Water Exposure Assessments: 2014 Update, September 9, 2014.

11 Guidance for Selecting Input Parameters in Modeling th e Environmental Fate and Transport of Pesticides

, Version 2.1, October 22, 2009.

12 The average 21-day concentration of chlorpyrifos-oxon necessary to cause 10% AChE inhibition was determined by HED to be 217 ppb. This value was divided by the safety factors (50x; 4.3 ppb) and then the contribution from food (0.4 ppb) was subtracted out to give to derive a DWLOC (3.9 ppb).

13 Dawson, J., Bohaty, R., Mallampalli, N. Evaluation of the Potential Risks from Spray Drift and the Impact of Potential Risk Reduction Measures, June 20, 2012 PC 059101 DP 399483 and 399485.

### 5 analysis (see the DWA for details) was completed to determine which chlorpyrifos uses do not exceed the DWLOC, based on a single application of chlorpyrifos per year at 1 and 4 pounds of chlorpyrifos per acre. The results for 1 and 4 pounds per acre are reported here as a representation of the range of potential chlorpyrifos application rates, bearing in mind that ch lorpyrifos can be applied at lower and higher single rates ( e.g., an application rate of 6 pounds per acre on citrus). This analysis showed that over a 30 year period, the current maximum application rate scenarios, as well as maximum single application rates for a wide range of chlorpyrifos use scenarios, may result in multiple 21-day average concentrations that exceed the DWLOC ( Figure 1 ).

Figure 1. National Screen: Exceedance Count/Percent (one application per year)

Regional Screen

Although there are several exceedances of the DWLOC on a national basis, the incidence of high exposures is expected to be highly localized. While it is currently extremely challenging to assess exposure on a local scale due to the unavailability of data and wide range of characteristics [ i.e.

, environmental such as soil, weather, etc. or otherwise ( e.g. , drinking water treatment process)] that affect the vulnerability of a given community drinking system to chlorpyrifos-oxon contamination, a method was developed to examine the potential geospatial concentration differences for two Hydrological Unit Code (HUC) 2 Regions

–HUC 2 Region 17: Pacific Northwest and HUC 2 Region 3: South AtlanticGulf, in order to identify use patterns that may result in EDWCs that exceed the DWLOC on a regional

basis. 14 

### This analysis considered all potential chlorpyrifos use sites within the HUC 2 regions based on the National Agricultural Statistics Service cropland data layers and survey data. Due to the uncertainty associated with some urban uses (e.g., wide area/gen eral outdoor treatment) that are represented by the impervious scenarios, modeled results from the imperv ious scenarios are not in cluded in this analysis. Additional clarification from the registrants is needed in order to determine if these uses pose an exposure

concern.

For HUC 2 Region 17, four chlorpyrifos scenarios were identified as a potential concern based on maximum single application rates of 1 and 4 pounds per acre. However, for HUC 2 Region 3, several chlorpyrifos use scenarios were identified that could exceed the DWLOC.

14 http://water.usgs.gov/GIS/huc.html

### 6 Watershed Screen

The uses that exceeded the DWLOC from the regional screening exercise for HUC 2 Region 3 were further explored for one example by utilizing the drinking water intake (DWI) watershed database. This example shows an overlap of potential chlorpyrifos us e sites that may result in an exceedance of the DWLOC with watersheds that supply source water for community drinking water systems. In addition, this analysis shows that exposure is not uniform within a HUC 2 Region and that some watersheds are more vulnerable than others. Watershed vulnerability is expected to be greatest for smaller watersheds with high percent cropped areas. Smaller community water systems are generally more vulnerable due to

short distribution times and the reliance of chlorination to treat source surface water as well as limited access to other treatment methods such as granular activated carbon.

Monitoring Data Analysis

Water monitoring data from the USGS National Water-Quality Assessment Program (NAWQA), USEPA/USGS Pilot Reservoir Monitoring Program, USDA Pesticide Data Program (PDP), and California Department of Pesticide Regulation (CDPR) were evaluated in the preliminary DWA with reference to an acute exposure to chlorpyrifos and its degradation product chlorpyrifos-oxon. The monitoring data showed chlorpyrifos detections at low concentrations, generally not exceeding 0.5 μ g/L. For example, USGS NAWQA, which contains an extensive monitoring dataset for chlorpyrifos and chlorpyrifos oxon, reports a peak chlorpyrifos detection of 0.57 μ g/L in surface water with a detection frequency of approximately 15%. CDPR has detected chlorpyrifos concentrations greater than 1 μ g/L in surface water on several occasions, with an obse rved peak chlorpyrifos concentration of 3.96 μ g/L. Sampling frequencies in these monitoring programs were sporadic and generally range from once per year to twice per month.

Since the preliminary assessment, water monitoring data from Washington State Department of Ecology and Agriculture (WSDE/WSDA) Cooperative Surface Water Monitoring Program 15,16 

### , Dow AgroSciences (MRID 44711601), and Oregon Department of Environmental Quality were evaluated and are presented as part of this update. The previously referenced data have also been re-examined to consider short-term exposure ( i.e. , 21-day average concentrations) considering the importance of the single day exposure and the temporal relationship of exposure. A summary of all surface water monitoring data examined to date for chlorpyrifos are presented in Table 2 . Some of the monitoring programs analyzed for chlorpyrifos-oxon; however , the number of detections, as well as the concentrations, was generally much lower. Since the majority of the conversion of chlorpyrifos to chlorpyrifos-oxon is assumed to occur during drinking water treatment, and not in the environment, the monitoring data presented in Table 2 are limited to chlorpyrifos.

15 Sargeant, D, Dugger, D. Newell, E., Anderson, P, Cowles , J. Surface Water Monitoring Program for Pesticides in Salmonid-Bearing Streams 2006-2008 Triennial Report, February 2010 (Washington State Department of Ecology and Washington State Department of Agriculture) https://fortress.wa.gov/ecy/p ublications/summarypages/1003008.html; http://agr.wa.gov/PestFert/natresources/docs/swm/2008_swm_report.pdf

16 Sargeant, D., Newell, E., Anderson, P., Cook, A. Surfac e Water Monitoring Program for Pesticides in SalmonidBearing Streams 2009-2011 Triennial Report, February 2013 (Washington State Department of Ecology and Washington State Department of Agriculture) http://agr.wa.gov/FP/Pubs/docs/377-SWM2009-11Report.pdf

### 7 Table 2. Surface Water Monitoring Data Summary for Chlorpyrifos

Monitoring Data Scale Years of Sampling (number of

samples) Detection Frequency (%) Maximum

Concentration ( μ g/L)

USGS NAWQA National 1991- 2012 (30,542) 15 0.57

California Department of Pesticide Regulation State 1991- 2012 (13,121) 20 3.96

Washington State Department of Ecology and Agriculture Cooperative Surface Water Monitoring Program State 2003- 2013 (4,091) 8.4 0.4

USDA Pesticide Data Program National 2004-2009 (raw water; 1,178)

2001- 2009

(finished water; 2,918) 0 na

USGS -EPA Pilot Drinking Water

Reservoir National 1999- 2000 (323) 5.3 0.034

Oregon Department of Environmental Quality Watershed (Clackamas) 2005- 2011 (363) 13 2.4

MRID 44711601 Watershed (Orestimba

Creek) 1996- 1997 (1,089) 61 2.22



### In general, the monitoring data include sampling sites that represent a wide range of aquatic environments including small and large water bodies, rivers, reservoirs, and urban and agricultural locations, but are

limited for some areas of the United States where ch lorpyrifos use occurs. Also, the sampling sites, as well as the number of samples, vary by year. In addition, the vulnerability of the sampling site to chlorpyrifos contamination varies substantially due to use, soil characteristics, weather and agronomic practices. None of the monitoring programs examined to date were specifically designed to target chlorpyrifos use (except the Registrant Monitoring Program MRID 44711601); therefore, peak concentrations (and likely 21-day average concentrations) of chlorpyrifos and chlorpyrifos-oxon likely went undetected in these programs. See the Revised Chlorpyrifos Preliminary Registration Review Drinking Water Assessment dated June 30, 2011 for further details on the monitoring programs discussed

here. http://www.regulations.gov/#!docum entDetail;D=EPA-HQ-OPP-2008-0850-0026

In general, sampling frequency needs to be approximately equal to the duration of exposure concern. 17


### The chlorpyrifos monitoring data evaluated thus far also show that as sample frequency increases, so does

17 U.S. Environmental Protection Agency. Federal Insecticid e, Fungicide, and Rodentic ide Act (FIFRA) Scientific Advisory Panel: Problem Formulation for the Reassessment of Ecological Risks from the Use of Atrazine, June 12- 14, 2012 , Docket Number: EPA-HQ-OPP-2012-0230.

### 8 the detection frequency. This is evident in the registrant-submitted monitoring data, as well as examination of individual sampling sites within the various datasets.

Therefore, while there are many individual samples collected and analyzed for chlorpyrifos (or chlorpyrifos-oxon) across the United States, it would not be appropriate to combine these data sources to generate exposure estimates or to use these datasets to represent exposure on a national or even regional basis. Thus, comparing the monitoring data result s to the DWLOC would not be a reasonable approach for the reasons given above, including limited samp le frequency, limited use information, and sampling site variability, on a national or even a regional basis. Model estimated concentrations should be considered suitable upper bound concentrations for chlorpyrifos and chlorpyrifos-oxon.

Additionally, model simulations were completed to represent two different water monitoring datasets - Washington State Department of Ecology and Agriculture (WSDE/WSDA) Cooperative Surface Water Monitoring Program and Dow AgroSciences (MRID 44711601) Orestimba Creek. For both of these water monitoring programs, enough information was available, including chlorpyrifos use information as well as the PCA, to parameterize the model. In these simulations, the modeled EDWCs were within an order of magnitude of the measured concentrations. Th is suggests that the modeling results are not overly conservative and supports the use of the model to estimate chlorpyrifos-oxon concentrations in drinking

water.

Additional modeling can be done to pinpoint regions or watersheds where EDWCs may exceed the DWLOC. This would include completing the regional assessment presented here for all HUC 2 Regions and crop uses, as well as considering multiple applications per year. Nevertheless, based on the current analysis, concentrations of chlorpyrifos-oxon in drin king water are expected to be highly localized primarily in small watersheds with high PCA.

Synopsis

In summary, examination of chlorpyrifos agricultural use across the country indicates that there are a number of uses that may result in potential exposure to chlorpyrifos-oxon in finished drinking water at levels that exceed the DWLOC. The EDWCs for tart cherries and bulb onion reported here are expected to provide a reasonable bounding estimation of exposure based on maximum rates included in the Master Use Summary Document . This analysis showed that the maximum use scenario for tart cherries exceeds the DWLOC, while it does not for bulb onions.

The rate used for the bulb onion simulation was 1 pound chlorpyrifos per acre; therefore a screen of all Surface Water Concentration Calculator modeling scenarios was done using a single application of chlorpyrifos. This analysis showed that exceedances are expected even for one application of chlorpyrifos applied at 1 pound per acre per year.

While there are uncertainties associated with the model input parameters for which conservative assumptions were made ( e.g. , one aerobic aquatic metabolism half-lif e value multiplied by the uncertainty factor of 3, stable hydrolysis, 100% of the cropped watershed is treated on the same day, and use of the Index Reservoir as the receiving waterbody), these assumptions do not appear to lead to an overly conservative estimate of exposure based on a comparison of model estimates with measured concentrations. Comparison of model estimated concentrations with measured concentrations suggests

that model estimates are consistent with measured concentrations when actual application rates and representative SWCC scenarios are considered and a PCA adjustment factor is applied to the model estimates. This modeling/monitoring comparison sugg ests that when growers use maximum application rates, or even rates much lower than maximum, chlorpyrifos-oxon concentrations in drinking water could pose an exposure concern for a wide range of chlorpyrifos uses. However, these exposures are not

### 9 expected to be uniformly distributed across the country. Additional analyses are needed in order to pinpoint the exact community water systems where concentrations may be of concern.

BACKGROUND

The 2001 Interim Reregistration Eligibility Decision (IRED) considered exposure to chlorpyrifos in drinking water 18,19 

### and recommended the quantitative use of monitoring data to estimate chlorpyrifos exposure. At the time of the IRED, chlorpyrifos concentrations in groundwater (greater than 2000 μ g/L) from termiticide uses were the primary focus of drinking water exposure. The model estimated concentrations were orders of magnitude lower than the measured concentrations. Subsequent to the IRED, the termiticide use was canceled.

The preliminary drinking water assessment conducted in 2011 1 

### recommended the use of surface water EDWCs for chlorpyrifos-oxon derived from modeling, and concluded that a range of chlorpyrifos uses could lead to high levels (peak concentrations greater than 100 μ g/L) of chlorpyrifos in surface water that could potentially be used by community water systems to supply drinking water. Once chlorpyrifos reaches a drinking water treatment facility, it re adily converts to chlorpyrifos-oxon upon disinfection(primarily oxidative treatment methods such as chlorination). Therefore, chlorpyrifos and chlorpyrifosoxon were considered residues of concern in the prel iminary assessment to account for the variation of drinking water treatment methods.

UPDATED MODELING SIMULATIONS

Revision of Metabolism Model Input Values

In December 2011, EFED along with Canada’s Pest Management Regulatory A gency (PMRA) completed the NAFTA degradation kinetics project. As part of this project, guidance 20 

### was developed describing a general approach for calculating and selecting representative half-life values from soil and aquatic transformation studies for risk assessment and exposure modeling. In 2013, EFED published a standard operating procedure (SOP) 21 

### for following the NAFTA kinetics guidance. Updated kinetic analyses were completed for chlorpyrifos following the recently updated SOP 22 

### using the PestDF Tool (version 0.8.13) along with R (version 3.1.0). The kinetic analyses are provided in APPENDIX 4: Kinetic analysis and

the results are summarized in Table 3

. Table 3 also provides the previously reported half-life values for comparison.

18 U.S. Environmental Protection Agency, Finalization of In terim Reregistration Eligibility Decisions (IREDs) and Interim Tolerance Reassessment and Risk Management De cisions (TREDs) for the Organophosphate Pesticides, and Completion of the Tolerance Reassessment and Reregist ration Eligibility Process for the Organophosphate Pesticides, September 28, 2001

19 Barrett, M, Nelson, H, Rabert, W., Spatz, D. Reregistr ation Eligibility Science Chapter for Chlorpyrifos Fate and Environmental Risk Assessment Chapter, June 2000

20 Guidance for Evaluating and Calculating Degr adation Kinetics in Environmental Media , Health Canada, U.S. Environmental Protection Agency, December 21, 2011.

21 Bohaty, R., Eckel, W., Shamim, M., Spatz, D., White, K. , Young, D. Standard Operating Procedure for Using the NAFTA Guidance to Calculate Representative Half-lif e Values and Characterizing Pesticide Degradation, November 20, 2013.

22 Bohaty, R., Eckel, W., Shamim, M., Spatz, D., White, K. , Young, D. Standard Operating Procedure for Using the NAFTA Guidance to Calculate Representative Half-lif e Values and Characterizing Pesticide Degradation, December 1, 2014 (Draft).

### 10 Table 3. Environmental Fate and Transport Characteristics of Chlorpyrifos

Parameter Test System

Name or

Characteristics Previously Report Half

- life

Values NAFTA Representative

Half- life Values (fitting model) Study ID Study Status

Laboratory Data

Aerobic Soil

Metabolism

Half- life

(t 1/2 ) Commerce 11 days 19 days (IORE)

Acc. 241547

MRID 00025619) Acceptable Barnes 22 days 36.7 days (IORE)

Miami 24 days 31.1 days (IORE)

Catlin 34 days 33.4 days (SFO)

Norfolk 102 days 156 days (DFOP) Stockton Clay 107 days 297 days (IORE)

German 141 days 193 (IORE) Sandy loam 180 days 185 days (DFOP) MRID 42144911 Acceptable

Aerobic Aquatic

Metabolism

Half- life

(t 1/2 ) Water, pH 8.1 Sediment, pH

7.7
25  ̊C 30.5 days 30.4 days (SFO) MRID 44083401 Supplemental

Anaerobic

Soil

Metabolism

half- life

(t 1/2 ) Commerce 15 days 78 (IORE)

MRID 00025619 Acceptable Stockton 58 days 171 days (SFO) Values represent

only anaerobic phase

Anaerobic

Aquatic

Metabolism

half- life

(t 1/2 ) Commerce pH 7.4 39 days 50.2 days (IORE)

MRID 00025619 Supplemental Stockton pH 5.9 51 days 125 days (SFO)



### Model Simulations

Groundwater
Tier I groundwater EDWCs for chlorpyrifos and chlorpyrifos-oxon were calculated using SCI-GROW (Screening Concentration in Groundwater, version 2.3, August 8, 2003) and PRZM-Groundwater (PRZM-GW version 1.0, December 11, 2012), using the GW-GUI (Graphical User Interface, version 1.0, December 11, 2012). 23 

### For Tier I groundwater assessments, the results from the model (either SCIGROW or PRZM-GW) that provides the highest EDWCs is recommended for incorporation into the human health assessment, along with surface water EDWCs in order to provide an upper bound estimation of the potential impact of chlorpyrifos use on drinking water supplies. Model input values for SCI-GROW and PRZM-GW are provided in Table 4 and Table 5 , respectively, and reflect current input parameter guidance. 11 

### Table 6 and Table 7 highlight the use scenarios simulated for Michigan tart cherries and Georgia onions ( i.e. , bulb onion production), respectively.

Based on the surface water EDWCs reported in th e preliminary drinking water assessment (see Figure 2) and the application rates included in the Chlorpyrifos Master Use Summary Document , chlorpyrifos applications to tart cherries is expected to prov ide upper bound EDWCs, while chlorpyrifos applications to bulb onion is expected to provide a lower bound value. These use scenarios were confirmed by the

23 http://www.epa.gov/oppefed1/models/water/

### 11 Biological and Economic Analysis Division (BEAD) as reasonably representative based on the maximum label rates for tart cherries and bulb onions prior to model simulations. 24



### Table 4

. SCI-GROW Input Parameters

Parameter (units) Input

Value Data Source Comments

Application Rate (lb a.i./A) See Table 6

and Table 7 Ma s ter Use Summary

Document Maximum yearly application rate is for tart

cherries and bulb onion (see ATTACHMENT

1 : Master Use Summary Document ).

Number of Applications See Table 6

and Table 7 Ma s ter Use Summary

Document For tart cherries the five different applications

were combined into one. (see ATTACHMENT

1 : Master Use Summary Document )

Soil Metabolism Halflife (days) 96 MRID 00025619 Half-life values of 19, 36.7, 31.1, 33.4, 156, 297, 193, and 185 days were obtained from empirical data following the NAFTA kinetics guidance.

The median half -life value of 96 days was u sed in SCI-GROW modeling.

K

oc (mL/g

oc ) 5860 Acc. 260794 Soil binding for chlorpyrifos is correlated with organic carbon content ( i.e. , the coefficient of

variation for K

oc values is less than that for K d values). The median K

oc value (K

oc values = 7300, 5860 and 4960 mL/g) was used for modeling.



### Table 5. PRZM-GW Input Parameters

Parameter (units) Input

Value Data Source Comments

Application Rate (kg a.i./ha)

See Table 6 Master Use Summary Document Maximum yearly application rate fo r chlorpyrifos is for

tart cherries and bulb onions (see ATTACHMENT 1 : Master Use Summary Document ). Number of Applications Application Date Annual Application

Retreatment Application Method

Hydrolysis Half

- life (days) 81 MRIDs 00155577 and

40840901 Since aerobic aquatic metabolism is not considered as part of groundwater modeling , a maximum hydrolysis value of 72 and 81 days was used in model simulations.

Aerobic Soil

Metabolism Half

- life (days) 170.6 Acc. # 241547 and

MRID 42144911 Half-life values of 19, 36.7, 31.1, 33.4, 156, 297, 193, and 185 days were obtained from empirical data follow ing the

NAFTA kinetics guidance. The 90th percentile confidence bound on the mean chlorpyrifos half

- life value is 118.9 + [(1.415 x 103.3)/√8)] = 170.6 days.

K

oc (mL/g

oc ) 6040 Acc. # 260794 Soil binding for chlorpyrifos is correlated with organic carbon content ( i.e. , the coefficient of variation for K

oc values is less than that for K d values). The mean K

oc value (K

oc values = 7300, 5860 and 4960 mL/g) was used for modeling.

24 Email from Clayton, Myers, RE: Chlorpyrifos Use March 26, 2014

### 12 Table 6. Michigan Tart Cherry Chlorpyrifos Application Scenario

Application

Number Application Timing; Type Date Method Application Rate (lb

a.i./A) Formulation Comments

1 Dormant/delayed Dormant; broadcast 4/1 A ircraft 2.0 liquid 150 ft. buffer for

aerial applications

2 Foliar; broadcast 5/15 Orchard blast 4.0 liquid 50 ft. buffer for

orchard blast applications

3 Foliar; broadcast 5/25 Orchard blast 4.0 liquid 50 ft. buffer for

orchard blast applications

4 Foliar; broadcast 6/4 Orchard blast 2.0 liquid 50 ft. buffer for

orchard blast applications

5 Foliar; Post harvest

trunk drench 8/1 Ground (hand

- held or

backpack) 2.5 liquid 25 ft. buffer for ground boom applications



### Table 7. Georgia Onion Chlorpyrifos Application Scenario

Application

Number Application Timing; Type Date Method Application Rate (lb

a.i./A) Formulation Comments

1 preplant; soil 12/4 Ground 1.0 liquid 25 ft. buffer for ground boom applications



### Figure 2. Summary of 1-in-10 Year Peak Chlorpyrifos-oxon EDWCs Previously Reported in the Preliminary Drinking Water Assessment for Registered Uses of Chlorpyrifos-oxon Derived From

Surface Water

The tart cherries use has the highest annual application rate (14.5 pounds per acre per year with a maximum single application rate of 4.0 pounds per acre ) of all the chlorpyrifos uses highlighted in the Master Use Summary Document . Tart cherries was also identified in the preliminary DWA as an application scenario with a high end exposure based on surface water simulations, even though it does not represent the highest single application rate scenario for chlorpyrifos. The highest single application rate

### 13 for chlorpyrifos is for citrus at 6.0 pounds per acre (10.5 pounds per acre per year). This annual rate reduction is not expected to substantially change the exposure estimates and; therefore, are not expected to alter the risk assessment conclusions. Bulb onion production in Georgia was identified as a lower bound scenario, as the maximum single and yearly application rate is 1 pound per acre. Although chlorpyrifos is not expected to pose a significant groundwater exposure (K

oc 

### > 1000 mL/g

oc 

### ), the tart cherries and bulb onion application scenarios were also considered for groundwater modeling.

Tier I groundwater EDWCs for chlorpyrifos and chlorpyrifos-oxon are provided in Table 8 and Table 9

, respectively. EDWCs are not expected to be greater than 0.16 μg/L for chlorpy rifos and 0.15 μg/L for chlorpyrifos-oxon (based on SCI-GROW). These EDWCs are expected to be an upper bound value and may not actually reflect groundwater concentrations ac ross the country, but rather reflect the potential exposure in vulnerable groundwater supplies. The reported groundwater EDWCs for chlorpyrifos-oxon are representative of drinking water supplies that utilize oxidative treatment methods such as chlorination. In general, drinking water taken from private wells is not treated; however, community drinking water supplied by wells may be treated with chlorine in order to protect drinking water during distribution.

Table 8. Estimated Drinking Water Concentrations of Chlorpyrifos in Groundwater

Crop/Scenario SCI-GROW PRZM-GW

μ g/L Highest Daily Value

μ g/L Post Breakthrough Average

μ g/L Average

Simulation Breakthrough

Time days

Tart Cherries

Florida Citrus

0.16 0.06

Incomplete with 100 year simulation Florida Potato 5.0E-11

Wisconsin Corn 9.4E-05 Georgia Peanuts 3.6E-08

North Carolina Cotton 2.9E-06

Delmarva Sweet Corn 0.0001

Bulb Onion

Florida Citrus

0.01 0.0043

Incomplete with 100 year simulation Florida Potato 3.9E-12

Wisconsin Corn 6.0E-06 Georgia Peanuts 2.6E-09

North Carolina Cotton 2.3E-07

Delmarva Sweet Corn 9.2E-06

### 14 Table 9. Estimated Drinking Water Concentrations of Chlorpyrifos-oxon in Treated Groundwater

Crop/Scenario SCIGROW PRZM-GW

ug/L Highest Daily

Value

μ g/L Post Breakthrough Average

μ g/L Average Simulation Breakthrough Time days

Tart Cherries

Florida Citrus

0.15 0.06

Incomplete with 100 year simulation Florida Potato 4.8E-11

Wisconsin Corn 9.0E-05 Georgia Peanuts 3.4E-08

North Carolina Cotton 2.8E-06

Delmarva Sweet Corn 0.0001

Bulb Onion

Florida Citrus

0.01 0.0041

Incomplete with 100 year simulation Florida Potato 3.7E-12

Wisconsin Corn 5.7E-06 Georgia Peanuts 2.5E-09

North Carolina Cotton 2.23E-07

Delmarva Sweet Corn 8.8E-06 EDWCs for chlorpyrifos-oxon were derived from EDWCs calculated for chlorpyrifos because chlorpyrifos is expected to transform to chlorpyrifos

- oxon during drinking water treatment. Chlorpyrifos EDWCs were multiplied by 0.9541 (molecular weight correction factor) and 100% (maximum conversion during water purification) to generate chlorpyrifos-oxon EDWCs.



### Surface Water
Tier II surface water EDWCs for chlorpyrifos and chlorpyrifos-oxon were calculated using the Surface Water Concentration Calculator (SWCC) version 1.106. The SWCC uses PRZM version 5.0+ (PRZM5) and the Variable Volume Water Body Model (VVWM). PRZM is used to simulate pesticide transport as a result of runoff and erosion from an agricultural field. VVWM estimates environmental fate and transport of pesticides in surface water. The input parameters used in SWCC simulations are presented in 

### Table

10

.



## National Screen

Tart cherries and onions were modeled as upper and lower bound exposure scenarios for surface water for reasons described above in the groundwater section of this assessment. Tier II EDWCs for surface water are presented in 

### Table 11 for chlorpyrifos in untreated surface water and chlorpyrifos-oxon following oxidative drinking water treatment. Tier II modeling results were corrected using the DWI PCA adjustment factor. 9,10 

### Since chlorpyrifos is registered for use on turf (including sod farms, golf courses, road medians and industrial areas) a PCA of 1 (consi ders 100% of the watershed can and is treated) wasapplied to surface water modeling results for this national screening analysis. EDWCs for chlorpyrifosoxon were derived from EDWCs for chlorpyrifos by multiplying chlorpyrifos EDWCs by 0.9541(molecular weight adjustment factor) and 100% (maximum conversion of chlorpyrifos to chlorpyrifosoxon during water treatment).

Although the model simulations suggest relatively high concentrations of chlorpyrifos in the receiving waterbody, only a small amount (≤ 1.2%) applied to the field re aches the water body for the two scenarios examined. This is consistent with a runoff study conducted by the registrant (MRID 00144906) that

### 15 suggests that the amount of chlorpyrifos transported from a treated field (corn watersheds in Illinois) to proximal water bodies is generally less than one percent of the applied material. 25 

### Depending on the scenario used in the modeling simulations, the transport of chlorpyrifos from the field to the receiving water body is either primarily through runoff or erosion ( Table 11 ) and the total mass transported from the field may be higher than 1.2% for other SWCC scenarios.

While model simulations consider the required aquatic spray drift buffers, these buffers may also reduce the transport of chlorpyrifos via runoff and erosion of chlorpyrifos from the field to the water body. Spray drift buffers provide distan ce between the field and the neighboring water body; however, it is unclear to what extent they may act like a filter strip. EFED does not currently have an exposure tool to assess the impact of vegetative filter strips (VFS) on reducing runoff and erosion; however, the development and maintenance of VFS is highly variable. Large runoff or erosion events are trigged by larger storm events, which are likely to overcome the buffer or VFS with sheet or channelized flow providing a direct conduit to the nearby water body. A U.S. Geological Survey (USGS) report suggests that sheet flow is expected at distances up to 100 feet. 26 

### Moreover, a review article on the redu ction of herbicide concentrations from fields with VFS was not able to document a decline in herbicide concentrations in receiving water bodies as a result of VFS, and that data specifically on a watershed scale is lacking. 27 

### In addition, this review concluded that retention of sediment as a function of the VSF width was nonlinear, with most of the retention occurring within the first few meters.

Once in the water body, chlorpyrifos dissipation is scenario specific; however, the primary mechanisms of chlorpyrifos dissipation are volatilization, metabolism and washout. Based on laboratory studies chlorpyrifos is expected to partition to sediment; however, this does not mean a complete reduction in chlorpyrifos in the water column is expected.

25 McCall, P. J., Oliver, G. R., McKeller , R. L. Modeling the runoff potential and behavior of chlorpyrifos in a terrestrial aquatic watershed (DowElanco unpublished report GH-C 1964) 1984

26 U. S. Department of Agriculture, National Resour ces Conservation Service, Small Watershed Hydrology WinTR55 User Guide, January 2009.

27 Krutz, L. J., Senseman, S. A., Zablotowicz, R. M., Matoch a, M. A., Reducing Herbicide Runoff from Agricultural Fields with Vegetative Filter Strips: A Review, Weed Science, 2005

, 53 , 353-367.

### 16 Table 10. SWCC Input Parameters
Parameter (units) Input Value Data Source Comments Molecular Weight (g/mol) 350.57 product chemistry

Water Solubility (mg/L) 20 °C 1.4 MRID

41829006 The water solubility of chlorpyrifos is reported to be

between 0.5 -2.0 mg/L for temperatures between 20- 25 °C. Based on data submitted to EPA, 1.4 mg/L was used in modeling.

Vapor Pressure (torr)

25 °C 1.87x10 -5 torr product chemistry

BC 2062713

Henry’s Law Constant 6.2 x 10 -6 atm -

m 3 /mol calculated

Application Rate (kg a.i./ha)

See Table 6 Master Use Summary

Document Maximum yearly application rate for use on tart cherries (see ATTACHMENT 1 : Master Use Summary

Document ). Tart cherries was also previously determined to be a high exposure scenario (see Figure 1 ) Number of Applications Application Date

Spray Drift 3.9% (aerial) a 0.9% (air blast) b

0.8 % (ground) c AgDRIFT modeling

based on label

restrictions Labels contain aquatic buffer distances of 25, 50 and 150

ft . for ground, airblast and aerial applications.

Application Efficiency 0.99 (ground; air-blast)) 0.95 (aerial) Default Values

Crop Application

Method See Table 6 Master Use Summary

Document Incorporation Depth

Hydrolysis Half

- life (days) 0 MRIDs

00155577

( Acc. # 260794) and

40840901 Since the aerobic aquatic metabolism half-life value was

not corrected for hydrolysis, it is possible that hydrolysis

would be double -counted in the model simulation. Therefore, hydrolysis was set to 0 (stable) here as it is already accounted for in the aerobic aquatic metabolism study and input parameter. Aqueous Photolysis (days) 29.6 MRID

41747206

Aerobic Soil

Metabolism Half

- life (days) 170.6 (109) Acc. # 241547

and MRID

42144911 Half-life values of 19, 36.7, 31.1, 33.4, 156, 297, 193, and 185 days were obtained from empirical data follow ing the

NAFTA kineti cs guidance. The 90th percentile confidence bound on the mean chlorpyrifos half

- life value is 118.9 + [(1.415 x 103.3)/√8)] = 170.6 days.

Aerobic Aquatic

Metabolism Half

- life (days) 91.2 (91.5) MRID

44083401 Only one half-life value is available, so this value (30.4 days) was multiplied by 3 to get 91.5 days. The 30.4 day

half -life value was not corrected for hydrolysis as hydrolysis data conducted under the same experimental

conditions w ere not provided. In addition, the aerobic aquatic metabolism study was conducted under slightly basic conditions (pH 7.7). Chlorpyrifos hydrolysis is pH dependent and faster under basic conditions.

Anaerobic Aquatic

Metabolism Half

- life (days) 203 (63) MRID

00025619 The 90 th percentile confidence bound on the mean chlorpyrifos half -life value determined following the NAFTA kinetics guidance is 87.6 + [(3.078 x 52.9)/√2)] =
202.7 days.

### 17 K

oc (mL/g

oc ) 6040 Acc. # 260794 Soil binding for chlorpyrifos is correlated with organic carbon content ( i.e. , the coefficient of variation for K

oc values is less than that for K d values). The mean K

oc value (K

oc values = 7300, 5860 and 4960 mL/g) was used for modeling.

Percent Cropped Area 1.0 PCA guidance d

a. Aerial: 150 ft. distance to water body from edge of f ield based on labeled buffer; ASAE fine to medium (dv 0.5 = 255

μ m; labels specify 255-340 μ m); Index Reservoir - downwind water body width 82 m (fraction applied 0.0331);

Streams

– 4 m (fraction applied 0.0552); Adjusted Spray dr ift fraction 0.0331 (spray drift fraction for the Index Reservoir) + [0.0552 (spray drift fraction for all Stream) x 0.114 (Surface areas of all streams/surface area of reservoir)] = 0.039

b. Air-blast: 50 ft. distance to water body from edge of fi eld based on labeled buffer; droplet size not specified; sparse (young, dormant); Index Reservoir - downwind water body width 82 m (fraction applied 0.0056); Streams

– 4 m (fraction applied 0.0265); Adjusted Spra y drift fraction 0.0056 (spray drift fractio n for the Index Reservoir) + [0.0265 (spray drift fraction for all Stream) x 0.114 (Surface area s of all streams/surface area of reservoir)] = 0.0086

c. Ground: 25 ft. distance to water body from edge of field based on labeled buffer; ASAE Fine to medium/cour se [dv 0.5 = 341 μ m; labels specify 255-340 μ m which is larger than ASAE very fine to fine (dv 0.5 = 175 μ m); highboom; 90 th
percentile; Index Reservoir - downwind water body width 82 m (fraction applied 0.0061); Streams

– 4 m (fraction applied 0.0164); Adjusted Spray drift fraction 0.0061 (spray drift fraction for the Index Reservoir) + [0.0164 (spray drift fraction for all Stream) x 0.114 (Surface areas of all streams/surface area of reservoir)] = 0.0079

d. See Footnotes 9 and 10

. Scenario: MICherriesSTD ; GAOnion_WirringSTD (Weather: W14850, W03822, respectively) EFED file room barcode (BC)



### Table 11. Estimated Drinking Water Concentrations of Chlorpyrifos in Untreated Surface Water (Model Output Values; PCA 1.0; all ag + turf)

Absolute

Peak 1-in-10 Year Concentration (ppb)

Relative Transport Field to

Water a Peak 21- day Average Annual Average 30 Year

Annual Average Michigan Tart Cherries

172 (164) b 129 (123 ) 83.8 (80.0) 39.2 (37.4) 29.7 (28.3) Runoff 18%

Erosion 77%

Drift 5% 1.2 %

Georgia Bulb Onion

8.5 (8.1) 6.2 (5.9 ) 3.1 (3.0) 1.2 (1.1) 0.8 (0.8) Runoff 78%

Erosion 18%

Drift 3% <1%

a. The relative amount of the material app lied to the field that is transpor ted off field and into the water body ( i.e. , index reservoir).

b. Bracketed concentrations are for chlorpyrifos-oxon in treated drinking water



### EFED recommends the use of the EDWCs presented in Table 11 in the human health risk assessment conducted for chlorpyrifos (and chlorpyrifos-oxon), as these values are expected to provide bounds on the exposure as a result of the currently registered uses as described in the Master Use Summary

Document . It should be noted that there are stil l a few uses, specifically urban uses ( e.g. , wide area treatment of miscellaneous pests) that need to be clarified in order to determine the potential exposure as

a result of these uses.

### 18 To screen the potential exposure resulting from the large number of other currently registered uses of chlorpyrifos, a batch run simulation was completed for one chlorpyrifos application per year for all current SWCC standard scenarios (n=124). A ground application was simulated for three different application dates; 30 days preemergence (-30dpe), 7 days postemergence (7dpe) and 30 days postemergence (30dpe).

While spray drift is expected to be higher for aerial applications, the application efficiency is higher for ground applications, and when both parameters are considered, the resulting EDWCs are generally similar. Therefore, if an exposure concern is triggere d for a ground application, it is expected that there would also be exposure concern for other application types including aerial and airblast applications.

EDWCs are highly sensitive to the application date, which is variable from year to year; therefore, examination of multiple application dates was done to better understand the potential variability in EDWCs as a result of application date. In addition, th e three selected application dates generally represent the various types [ i.e. , timing of application permitted ( e.g. , pre-plant, at plant, foliar, and dormant)] of applications currently allowed for a number of the registered uses of chlorpyrifos.

Figure 3 presents the range of the highest 21-day aver age chlorpyrifos-oxon concentrations for each of the application dates assessed for all scenarios comp ared to the DWLOC for chlorpyrifos-oxon resulting from chlorpyrifos applications at 1 pound per acre. The national default DWI PCA of 1 for all agricultural and turf was used in this analysis. Absent from this analysis are the impervious scenarios ( i.e.

, CAImperviousRLF), due to the uncertainty associated with the registered uses that are represented by these scenarios. As mentioned above, clarification from the registrants is needed in order to determine if these uses pose an exposure concern.

Figure 3. National Screen: Estimated Chlorpyrifos-oxon Concentration by Scenario (one application per year)

Figure 4 presents the total number of exceedance periods ( i.e. , 21-days) over the entire model simulation (approximately 30 years, but is scenario dependent) for the application date that results in the highest number of exceedances calculated for 1 and 4 pound(s) per acre for each standard SWCC scenario. Also shown are the number of exceedances that correspond to the 99.9 th 

### , 99 th 

### , and 90 th 

### percentiles, i.e., 10, 100, and 1000 exceedances, respectively. The exceedance count was calculated using an Excel macro to screen the daily concentration time series files generated by the SWCC. For this analysis, the 21-day

DWLOC 28 

### for chlorpyrifos-oxon was adjusted by the molecular weight adjustment factor to calculate the corresponding chlorpyrifos concentration for use in th e Excel macro, since the time series data generated

28 3.9 ppb oxon / 0.9541 oxon molecular weight adjustment factor = 4.1 ppb chlorpyrifos 0 5 10 15 20 25 30TXsorghumOPSTXvegetableN...PAtomatoSTDPAAppleSTDKSsorghumSTDPRcoffeeSTDMSsoybeanSTDFLpeppersSTDCAWheatRLFFLcucumberSTDNCpeanutSTDSTXcottonNMCCARangelandh...CAColeCropRLFCAWineGrapes...NCcornWOPNDWheatSTDFLtomatoSTDORBerriesOPNJnurserySTDCAAvocadoRLFNDcornOPWAbeansNMCCAsugarbeet_...CAonion_Wirri...ORFilbertsSTDORAppleSTDCAcotton_Wirri...IDNpotato_Wir...TurfBSSCAresidentialRLFConcentration (μg/L)

Scenario DWLOC National Screen 1 lb a.i./A

Range of Highest 21-day Average

Concentration

DWLOC

### 19 by the SWCC are for chlorpyrifos and does not consider the transformation of chlorpyrifos to chlorpyrifos-oxon as a result of drinking water treatment. An uncertainty with using the 21-day average concentration as the DWLOC is the temporal relationsh ip of chlorpyrifos and corresponding chlorpyrifosoxon concentrations from day to day. For example, a one day exposure concentration may result in an average 21-day concentration that exceeds the 21-d ay DWLOC while a more constant exposure over 21 days may also result in an average 21-day concentration that exceeds the 21-day DWLOC. Alternatively a one day exposure concentration may not trigger a risk concern using this approach, as the average 21-day concentration may be below the DWLOC.

Figure 4. National Screen: Exceedance Count/Percent (one application per year)

Not all the SWCC scenarios represen t use sites where 4 pounds of chlorpyrifos can be applied; therefore, the results presented in Figure 4 are only for those SWCC scenarios that reasonably represent use sites where chlorpyrifos can be applied at a single application rate up to 4 pounds per acre. For the graphs, the left y-axis corresponds to the number of 21-day time periods where the average concentration exceeds the DWLOC. There are approximately 10,000 21-day time periods per 30 year simulation. The labels on the right y-axis represents the DWLOC exceedance pe rcentile based on the total number of 21-day time periods. 29



### Considering maximum single application rates and the re presentation of the scenarios, at least one 21-day average concentration was determined to be greater than the DWLOC for all use sites/crops except for

29 Exceedance Count/~10000; the actual number of days included in each simulation was considered 1 10 100 1000 10000Highest Exceedance (count)

Scenario DWLOC National Screen 4 lb a.i./A

Exceedance Count 90 th percentile

99.9 th percentile 99 th percentile

### 20 pumpkin ( Table 12 ). A summary of the results for all the scenarios and all application rates [1, 2 (2.3 for citrus scenarios), 3, 4, and 6 pounds] is provided in ATTACHMENT 2

. Table 13 provides a snapshot of the scenarios that result in a 21-day average concen tration that exceeds the DWLOC, and examples of the represented uses. This is not intended to be a comprehensive list, but rather to associate the simulated scenario to chlorpyrifos use scenarios.

Using this approach, the number of 21-day exceedan ce periods associated with a single event cannot easily be parsed out, nor can the number of 21-day exceedance periods associated with individual events. Note that the application date that results in the highest 21-day average concentration does not always correspond to the application date that results in the highest number of 21-day averaging periods that exceed the DWLOC. In addition, examination of the EDWC exceedances across the modeled scenarios highlight that exposure concentrations of chlorpyrifos and chlorpyrifos-oxon are not expected to be uniform across the country.

Table 12. National Screening Results Using DWLOC Approach

– Scenario Representation and Labeled Rate Comparison for Uses that Do Not Exceed the DWLOC

Use Site/Crop (representative scenario) Highest a 21-day Average Concentration ppb (application date) Maximum Single Application Rate Comments

Pumpkin (FLCucumbersSTD) 3.3 ( -30dpe)

– at 0.3 lb

a.i./A 0.3 (aerial and ground liquid) This is a preplant seed

treatment and assumes 100% of the applied

material washes off the

seed coat in the field and is available for transport.

a. Referenced EDWCs reflect highest 21-day averag e concentration calculated for each of the three application dates simulated.

### 21 Table 13. National Screening Results Using DWLOC Approach

– Scenario Representation and Labeled Rate Comparison for Example Uses that Exceed the DWLOC

Scenario Highest 21-day Average Concentration ppb (application date) 21-day Exceedance

Count Represented Use Site Examples (maximum single application rate) Highest a (application

date b ) Percent c



### 1 lb a.i./A

MScornSTD 16.5 (-30dpe) at 1.0 lb a.i./A 2273 21 Corn [2 lb a.i./A (aerial and ground)] Soybean [1 lb a.i./A ( aerial ); 2.2 (ground)] TXcornOP 13.9 (30dpe) at 1.0 lb a.i./A 1418 13

ILcornSTD 14.6 (30dpe) at 1.0 lb a.i./A 1697 (-30pde) 16

MScotton 19.8 (-30dpe) at 1.0 lb

a.i./A g 1697 16 Cotton [1 lb a.i./A ( foliar aerial and ground) ; seed treatment

permitted at 2.2 lb a.i./A] NCcotton 14.4 (7dpe) at 1.0 lb a.i./A 2768 (-30pde) 25

TXcotton 15.1 (30dpe) at 1.0 lb a.i./A 868 8

NYgrape 15.7 (

- 30dpe) at 1.0 lb a.i./A 2918 (30pde) 27 Grape [2.25 lab a.i./A (ground)]

TXsorghumOP 25.8 (30dpe) at 1.0 lb a.i./A 1328 (-30pde) 12 Wheat [1 lb a.i./A (aerial and ground)] Sunflower [2 lb a.i./A ( aerial and ground)]

Other Grains: Sorghum [3.3 lb a.i./A (granular) d ] Alfalfa [1 lb a.i./A (aerial and ground)] TXwheatOP 21.0 (-30dpe h ) at 1.0 lb

a.i./A 705 6

PAVegetableNMC 21.1 (30dpe) at 1.0 lb a.i./A 1972 (7dpe) 18 Vegetables and Ground Fruit: Strawberry [2 lb a.i./A ( aerial and ground)] Radish [3 lb a.i./A (ground) f ] Pepper [1 lb a.i./A (ground)] Onion [1 lb a.i./A (ground)] CAlettuce 12.8 (

- 30dpe) at 1.0 lb a.i./A 840 8

MEpotato 10.7 (-30dpe) at 1.0 lb a.i./A 1857 17 Other Row Crops: Tobacco [2 lb a.i./A ( aerial and ground)] Sugarbeets [2 lb a.i./A (granular) d ] Peanuts [4 lb a.i./A (granular) e ] Sweet Potato [2 lb a.i./A (aerial and ground)] NCsweetpotatoSTD 13.5 (30dpe) at 1.0 lb a.i./A 1006 9

2 lb a.i./A

MIcherriesSTD 19.6 (30dpe) at 2.0 lb a.i./A 4574 42 Orchards and Vineyards (Tree fruit and Nuts): Fruit and Nuts [4 lb a.i./A (ground)] Pecans [2 lb a.i./A (air); 4.3 (ground)] Apple [2 lb a.i./A (air and ground)] Peach [2 lb a.i./A (air); 3 (ground)] GApecansSTD 20.7 (-30dpe) at 2.0 lb a.i./A 1353 (30dpe) 12

PAapples 29.1 (30dpe) at 2.0 lb a.i./A

1212 11

### 22 NCPeanutSTD 21.0 (30dpe) at 2.0 lb

a.i./A 2282 (- 30dpe) 21 Peanut 2.0 lb a.i./A (aerial and ground)

4 lb a.i./A (granular ground)

FLCitrusSTD 10.1 (30dpe) at 2.0 lb

a.i./A 684 6 Citrus

6.0 lb a.i ./A [ground including airblast] 2.3 lb a.i./A (aerial)

a. The highest number of 21-day time periods where the average concentration ex ceeds the DWLOC of the three use scenarios considered ( i.e. , application date -30dpe, 7dpe, or 30dpe).

b. If different than the application date reported for the highest 21-day average concentration.

c. The highest percent of 21-day time periods wh ere the average concentration exceeds the DWLOC. There are approximately 10,000 21- day time periods per 30 year simulation; however, it should be noted that not all scenarios contain exactly 30 years of weather data.

d. [1.0 (air and ground)]

e. [2.0 (air and ground)]

f. Incorporated or in furrow otherwise [1.0 (air and ground)]

g. A preplant seed treatment is permitted at 2.2 lb a.i./A and assumes 100% of the applied material washes off

the seed coat in the field an d is available for transport.

h. The application date that resulted in the highest 21 -day average concentration does not represent the registered use; however, the other applic ations dates also resu lt in exceedances (21- day average EDWCs range from 7.1- 8.2 for the two application dates)



### Typical use rates were also examined for Michigan tart cherries to characterize what the actual exposure may be as a result of current use practices. For this analysis, two applications at 2 pounds per acre were assumed since the upper bound typical rate for cherries is 2 pounds per acre (99.6 th 

### centile) with an average number of applications of 1.1 per year. 30 

### The use scenario modeled is provided in Table 14 while the results are presented in Table 15 . A national DWI PCA of 1 was considered for this analysis. The regional maximum PCA for HUC 2 Region 4: Great Lakes, where tart cherries are predominately grown, is also 1. If only the orchards and vineyards crop group is considered, the maximum DWI PCA in HUC 2 Region 4 is 0.05. This suggests the relative contributi on (ignoring the application rate and corresponding EDWC) of chlorpyrifos transported to an aquatic body as a result of an application to tart cherries is expected to be lower than the contribution from other use sites within the watershed. If the only chlorpyrifos use permitted within this region was orchards and vineyards, the resulting EDWCs would not be expected to exceed the DWLOCs.

Additional analyses are needed in order to determine if other uses within HUC 2 Region 4 would result in an exposure concern. Considering only the maximu m DWI PCAs calculated for individual crop groups within the HUC 2 Region 4, corn (PCA = 0.35), soybean (PCA = 0.20), and turf (PCA = 0.85) are likely to present the highest exposure concerns.

Table 14. Typical Michigan Tart Cherry Chlorpyrifos Application Scenario

Application

Number Application Timing; Type Date Method Application Rate (lb a.i./A) Formulation Comments

1 Dormant/delayed Dormant; broadcast 4/30 Orchard

blast 2.0 liquid 50 ft. buffer for

orchard blast applications

2 Foliar; broadcast 6/1 Orchard

blast 2.0 liquid 50 ft. buffer for

orchard blast applications

30 Becker, J., Stebbins, K., Typical Use Data for Chlorpyrifos

, June 24, 2011

.

### 23 Table 15. Estimated Drinking Water Concentrations of Chlorpyrifos in Untreated Surface Water (Model Output Values; PCA 1.0; all ag + turf) for Typical Use on Tart Cherries

Absolu te

Peak 1-in-10 Year Concentration (ppb)

Relative Transport Field to

Water a Peak 21- day Average Annual Average 30 Year

Annual Average Michigan Tart Cherries

55.2 (52.7 ) b 40.0 (38.2) 25.8 (24.6) 10.6 (10.1) 7.9 (7.5) Runoff 18%

Erosion 80%

Drift 2% 1.2%

a. The relative amount of the material app lied to the field that is transpor ted off field and into the water body ( i.e. , index reservoir).

b. Bracketed concentrations are for chlorpyrifos-oxon in treated drinking water



### In summary, this analysis shows that the current maximum single application rates for a wide range of chlorpyrifos use scenarios may result in a 21-day average concentration that exceed the DWLOC. Again, this DWLOC approach does not consider the temporal aspects of the exposure concentrations on AChE inhibition or the geospatial distribution of exposure, but provides a means to easily identify use patterns

that should not result in EDWCs that exceed the DWLOC.



## Regional Screen

To examine the potential geospatial concentration differences, a regionally-specific analysis was completed for two Hydrological Unit Code (HUC) 2 Regions

– HUC 2 Region 3: South Atlantic-Gulf and HUC 2 Region 17: Pacific Northwest. These two HUC 2 regions were selected to represent the range of SWCC standard scenarios that fall within the HUC 2 regions, the different chlorpyrifos use scenarios expected to occur within the HUC 2 region, as well as to provide a reasonable representation of the bounds of potential exposure on a regional basis. The same model simulations that were used in the national screen were used in this analysis; however, regional DWI PCAs, as well as the molecular weight adjustment factor, were used to adjust the EDWCs to estimate the potential exposure to chlorpyrifos-oxon in drinking water. The maximum regional DWI PCAs for all agriculture plus turf are 0.74 and 0.65 for the Pacific Northwest and the South Atlantic-Gulf HUC 2 Regions, respectively.

The total number of exceedance periods ( i.e. , 21-days) over the entire model simulation (approximately 30 years) for the application date that results in the highest number of exceedances calculated for 1 and 4 pound(s) per acre for each standard SWCC scenario that falls within the HUC 2 Region are presented. The exceedance count was calculated using the Excel macro mentioned above; however, the 21-day DWLOC for chlorpyrifos-oxon was adjusted by the molecular weight adjustment factor as well as the maximum regional DWI PCA to calculate the corresponding chlorpyrifos concentration, since the time series data generated by the SWCC are for chlorpyrifos. The corresponding chlorpyrifos concentrations

are 5.5 μ g/L 31 

### and 6.3 μ g/L 32 

### for the Pacific Northwest and the South Atlantic-Gulf HUC 2 Regions, respectively. The results of this analysis are presented in Figure 5 for HUC 2 Region 17: Pacific Northwest for a single application of chlorpyrifos at 1 and 4 pounds per acre. The results for HUC 2 Region 3: South Atlantic-Gulf are provided in Figure 6 for a single application at 1 and 4 pounds per acre. Only the results from the scenarios that reasonab ly represent current chlorpyrifos uses within the respective regions are presented in these figures.

31 3.9 ppb chlorpyrifos-oxon / 0.9541 / 0.74 = 5.5 ppb chlorpyrifos

32 3.9 ppb chlorpyrifos-oxon / 0.9541 / 0.65 = 6.3 ppb chlorpyrifos

### 24 Figure 5. Regional Screening Results Using DWLOC Approach for HUC 2 Region 17: Pacific

Northwest

Figure 6. Regional Screening Results Using DWLOC Approach for HUC 2 Region 3: South

Atlantic-Gulf

For HUC 2 Region 17: Pacific Northwest, exceedances are only observed for two scenarios (ORSWCornOP and ORBerriesOP) at a single application rate of 1 pound per acre. When a single application rate of 4 pounds per acre is considered, several scenarios (ORFilbertSTD, ORGrassSeedSTD, ORAppleSTD, ORXmasTree) result in 21-day average concentrations that exceed the DWLOC. The tree 1 10 100 1000 10000

ORFilbertsSTD ORGrassSeedSTD ORAppleSTD ORXmasTree WAOrchardsNMCHighest Exceedance (count)

Scenario Adjusted DWLOC HUC2 Region 17 Screen 4 lb a.i./A

Exceedance Count

99.9 th percentile 99 th percentile 90 th percentile

1 10 100 1000 10000Highest Exceedance (count)

Scenario Adjusted DWLOC HUC2 Region 3 Screen 1 lb a.i./A

Exceedance Count

99.9 th percentile 90 th percentile

99 th percentile

### 25 fruit and nut fruit scenarios may represent a 4 pounds per acre application rate for chlorpyrifos applied to fruit and nuts trees [for non-bearing (not to bear fruit within 1 year)] in nurseries including: almonds, citrus, filbert, apple, cherry, nectarine, peach, pear , plum, and prune]. Additional clarification is needed on this use to confirm that this scenario represents the registered use. The grass seed scenario is representative of the potential use sites for orname ntal lawns and turf and sod farms. However, the maximum single application rate is 3.76 pounds per acre. The concentrations will be slightly lower than those calculated for a 4 pound application, reducing the number of likely exceedances.

In contrast to the results presented for the Pacific Northwest, a larger number of scenarios (primarily representing corn, cotton, soybean, and vegetable and ground fruit, and fruit and nut tree use sites) were determined to result in 21-day average concentr ations that exceed the DWLOC when only a single application rate at 1 pound per acre is considered. Mo re exceedances are expected for higher application rates; however, not all of the SWCC scenarios considered in the 1 pound analysis would be representative of use sites where higher chlorpyrifos applications are permitted.

This analysis underscores the regional exposure variations that likely exist across the United States. For those scenarios where exceedances are already expected, more exceedances would be expected for multiple applications. However, for those use scenar ios where a single application does not result in exceedances, additional analyses are needed to explore the potential of multiple applications per year, as this screen only considered one application per year. Similar to the national analysis, this regional approach does not parse out the number of 21-day exce edance periods associated with a single event, or the number of 21-day exceedance periods associated with individual events within a given year. Furthermore, the temporal variability in concentrations is an uncertainty.

This regional analysis does not confirm overlap of potential chlorpyrifos use sites with vulnerable watersheds. To investigate this further, potential use sites ( i.e. , corn 33 

### ) were overlaid with the drinking water intake delineated watersheds ( Figure 7) . The watersheds with a maximum yearly 21-day average

concentration that exceeds the DWLOC are shaded in Figure 7

. The cropland overlay used is for corn and does not take into account other chlorpyrifos uses that occur within the HUC 2 Region. However, the average pounds of chlorpyrifos applied per 1,000 acres of farmland by state was used to highlight the chlorpyrifos expected use intensity within the region. These data should not be used as a means to calculate an application rate for chlorpyrifos per acre as the data are provided in terms of acres of total farmland and not acres of farmland treated with chlorpyrifos. It should be noted that use information on a smaller scale ( e.g. , crop reporting district, county or watershed) may be available; however, the sample size for small geographical areas are generally low.

There are a number of known DWIs that do not have delineated watersheds. For some of these DWIs, surrogate PCAs have been assigned from the HUC 12 region PCAs 34 

### that encompass the intake, while

other known intakes 35 

### do not have a surrogate PCA at this time. None of these intakes or surrogate HUC 12s are presented in Figure 7 . Additional analysis could be done, overlaying the intake locations that do not have PCAs with potential chlorpyrifos use sites.

33 Cropland Data Layer for corn aggregated for the years 2010 through 2013

34 634 surrogate HUC 12 PCA were developed for the United States

35 761 “new” intakes and 359 canals or aqueducts

### 26 Figure 7. Region 3: South Atlantic-Gulf: Corn Cropland Overlay with Drinking Water Intake Watersheds Where the 21-day Average Concentrations are expected to Exceed the DWLOC

Figure 8 provides the ranking distribution of the highes t 21-day average EDWCs for the three application dates assessed for HUC 2 Region 3 for corn. This distribution does not include DWIs that have been assigned a surrogate HUC 12 PCA, or those intakes wh ere a PCA has not been developed. The y-axis of

### 27 this graph represents the highest 21-day average conc entration, while the x-axis represents the relative rank of the 21-day average concentration for each of the DWI watersheds ( i.e. , DWI PCA corrected EDWCs) from the highest to the lowest. This distribution suggests that depending on the application date, there is generally more than one (n=13) community drinking water system that could be using source surface water for supplying drinking water where a 21- day average concentration of chlorpyrifos or the corresponding chlorpyrifos-oxon is estima ted to be higher than the DWLOC.

For additional characterization, the exceedance count for the DWIs where the 21-day average concentration is expected to exceed the DWLOC at least once was determined. These results are presented in Figure 9

.

Figure 8. Regional Distribution of the Maximum Yearly Corn 21-day EDWC for DWI Watershed in Region 3: South Atlantic-Gulf

Figure 9. Regional Screening Results Using DWLOC Approach for Vulnerable Drinking Water Intakes Falling Within HUC 2 Region 3: South Atlantic-Gulf;

While the field size and the index reservoir (the receiving water body) used in the SWCC simulations may provide reasonable upper bound EDWCs on a national scale, the watershed sizes and the receiving 

## 0 

## 2 4 6 8Chlorpyrifos-oxonConcentration (μg/L)



## Rank 

# HUC 2 Region 3 - South Atlantic-Gulf DWI
PCA Adjusted Corn EDWCs

DWLOC

DWI PCA

Corrected

EDWCs

1 10 100 1000 10000

2527672-4 1825516-4 3959677-4 2504980-4 2645548-1 3041357-3 2878941-1 5568697-1 3959676-4 3493772-4 3959073-1 1768880-1 5148864-4Highest Exceedance (count)

Basin-Identification Adjusted DWLOC HUC2 Region 3 Screen 1 lb a.i./A

Exceedance Count

99.9 th percentile 90 th percentile

99 th percentile

### 28 water bodies represented by the DWI dataset vary substantially from very large to very small ( Figure 10 ). The index reservoir represents a vulnerable drinking water scenario in the Midwest ( i.e. , Shipman City Lake in Shipman, Illinois) and although the index reservoir serves as a screening tool, it represents the drainage area/normal capacity of a drinking water reservoir in other parts of the United States. 36 

### In addition, as the water body size changes, the relative watershed size is also expected to change. Therefore, the mass coming from the treated watershed relative to the waterbody volume may stay relatively the same for vulnerable scenarios. Nevertheless, the assumption that the entire watershed is treated with chlorpyrifos on the same day at the same rate is like ly conservative for larger watersheds (27,887 square mile; 95 th 

### centile). However, as the watershed size decreases it is more likely that an entire watershed could be treated with chlorpyrifos on the same day, especially when considering some of the small watersheds (1 square mile; 10 th 

### centile). The index reservoir is approximately 0.67 square miles.

Figure 10. Drinking Water Intake Watershed Size Distribution

Based on the regional analysis for HUC 2 Region 3, up to 3% of the watersheds may have chlorpyrifos concentrations high enough that upon drinking water treatment, the concentration of chlorpyrifos-oxon will exceed the DWLOC resulting from chlorpyrifos application made to corn at 1 pound per acre. In addition, this analysis shows there is overlap with th e potential use sites (corn) and known chlorpyrifos use with watersheds that supply source surface wa ter for community drinking water systems. This analysis also demonstrates that even within a HUC 2 region, there is a wide range of estimated concentrations that are expected to be highly localized ( e.g. , watershed/community drinking water system); however, the community water systems where chlorpyrifos and chlorpyrifos-oxon exposure is expected to be higher than the DWLOC can be identified with reasonable certainty.

Additional analysis is needed in order to appropriately characterize the expected exposure for other chlorpyrifos uses within HUC 2 Region 3, as well as the intakes that do not have delineated watersheds or surrogate HUC 12 PCAs. Examination of the other HUC 2 Regions could be completed.

36 U.S. Environmental Protection Agency. Federal Insecticid e, Fungicide, and Rodentic ide Act (FIFRA) Scientific Advisory Panel: Proposed Methods for Basin-scale Estimati on of Pesticide Concentrations in Flowing Water and Reservoirs for Tolerance Reassessment; Linear Low Dose Extrapolation for Cancer Ri sk Decisions; DDVP Risk Issues; FQPA 10 Safety Factor Status Report; and Chlo rothalonil: Mechanism for the Formation of Renal and Forestomach Tumors, July 29-30, 1998

. 

### 0.00 0.25 0.50 

### 0.75 1.00

0.001 0.100 10.000 1,000.000 100,000.000Rel. Frequency



### Watershed Area (sq. mi.)

### 29 ADDITIONAL ANALYSES

Modeling and Monitoring Data Comparison

As part of the preliminary DWA, several sources of surface water and groundwater monitoring data were examined. Sources included: USGS National Water-Quality Assessment Program (NAWQA), USEPA/USGS Pilot Reservoir Monitoring Program, USDA Pesticide Data Program (PDP), California Department of Pesticide Regulation (CDPR), and Na tional Center for Water Quality Research (NCWQR) at Heidelberg College. 37,38 

### In summary, the monitoring data showed that detections of chlorpyrifos are much more likely to occur in surface water than groundwater, and concentrations in surface water are generally higher than groundwater.

We conclude from our analysis of the available surfac e water monitoring data that it likely underestimates chlorpyrifos and chlorpyrifos-oxon concentrations in drinking water, and thus it is not recommended for quantitative risk assessment purposes. These water monitoring sampling programs did not specifically target chlorpyrifos use and likely do not represent high chlorpyrifos use areas. In addition, sample timing may not have corresponded with applications or runo ff events; therefore, detections cannot be directly associated with a particular use pattern or site. In addition, monitoring locations, sampling frequencies, and sampling timing were not designed to capture peak concentrations. Model generated times series data along with anticipated use ( i.e. , sporadic) suggest that monitoring programs need to sample frequently in order to capture peak concentrations of chlorpyrifos in surface water. Even in the case of a pesticide such as atrazine, which has a more consistent use pattern, the sample frequency should be daily, otherwise a bias factor is recommend to be applied to ensure peak concentrations are captured. 39



### Since the finalization of the preliminary DWA, three additional water monitoring datasets were evaluated. The Washington State Department of Ecology and Agriculture (WSDE/WSDA) Cooperative Surface Water Monitoring Program published two reports on multi-year aquatic monitoring studies conducted in Washington. 15,16 

### Dow AgroSciences submitted data (MRID 44711601) for a surface water monitoring study conducted on a tributary of the San Joaquin River in California. A summary of these studies is provided below.

California (Registrant Monitoring Program MRID 44711601)

Sampling was conducted at three locations on the lower reach of Orestimba Creek for one year (May 1, 1996 to April 30, 1997). Daily time-proportional composite samples 40 

### were collected, along with weekly samples. The report included chlorpyrifos use information for fields that drained into the creek or had the potential to contribute spray drift 41 

### . All chlorpyrifos applications were made to alfalfa and walnut by aerial equipment and were made during the irrigation season. The total mass of chlorpyrifos applied to all the fields that were identified to have the potential to impact the creek was 2.2 lb a.i./A (1308 kg).

37 Note, at the time of the preliminary DWA was completed the NCWQR data had not been thoroughly reviewed by

EPA and since this time the authors have indicated that proper quality assurance and quality control standards may

not have been met.

38 A discussion of each of the individual datasets is provided in the preliminary assessment.

39 U.S. Environmental Protection Agency. Federal Insecticid e, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel Meeting: Problem Formulation for the Reassessment of Ecological Risks from the Use of Atrazine, June 12-14, 2012 , Docket Number: EPA-HQ-OPP-2012-0230

40 Hourly samples were collected and composited over a 24- hour period; relatively large fluctuations in stream flow were anticipated during unattended operation of the auto samplers

41 Fields within 305 m buffer on either side of the mid-stream line

### 30 Applications occurred throughout the study period (or the day prior to study initiation) with, at most, three fields treated in the study area on the same day. The report suggests that typical chlorpyrifos use occurred during the study period, with the exception of dormant season applications to tree crops, which were limited due to the rainy weather during the study.

The measured concentrations at the three sample locations are provided in Figure 91 . The highest

measured concentration was 2.2 μ g/L and was associated with a chlorpyrifos application to alfalfa followed by flood irrigation.

In several cases, the weekly grab samples were observed to have higher concentrations of chlorpyrifos. This suggests that the composite sampling methodology used in the study for daily samples resulted in the dilution of peak daily concentrations. Thirteen chlorpyr ifos peak concentrations could be associated with specific events. The report authors suggest that nine of the events were related to spray drift (peak concentrations occurring within a three day window of application,) and were not linked to an irrigation event. The other four events were linked to irrigation tail water. Flood irrigation was reportedly used in the treated fields. Most of the peak concentrations were observed following chlorpyrifos applications to walnuts. The report noted that many of the walnut orchards are planted adjacent to the creek with an outside row located on the creek bank. This practice was done to maximize drainage from the orchard floor directly into the stream channe l. It is unclear if any buffer zones were in place during application, but the observed concentrations suggest that the spray drift occurred during application even in the

absence of adverse wind conditions.

Figure 91. Orestimba Creek Water Monitoring Data (May 1, 1996 to April 30, 1997)

Not all monitored concentrations were observed shortly after the application event. There is one example where the peak measured concentration (0.32 μ g/L) associated with an application event occurred 56 days after application. The detection was associated with an irrigation event. This suggests that chlorpyrifos residues available for transport may persist on the field for several days (approximately two months) after application. No detections of chlorpyrif os were observed during the rainy season.

Representative model simulations were completed for comparative purposes and are presented in

### 31 

### Table 16 . The scenarios used in this analysis are provided in



### Table 16

, while chemical specific model input values are provided in 

### Table 10 . The estimated peak concentrations are higher than the measured concen trations; however, the estimated concentrations are within an order of magnitude of the measured concentrations.

The estimated concentrations are expected to be highly conservative for a few reasons. A PCA adjustment factor was not applied and it is known that the entire watershed was not treated on the same day or planted with crops that chlorpyrifos may be applied. The report noted that approximately 80 percent of the watershed was forest. If the remaining watershed was assumed to be treated (PCA = 0.20) the peak estimated concentrations are in reasonable agreemen t with the measured concentrations. Also, the amount of chlorpyrifos applied to the entire area of influence was only 2.2 lb a.i./A spread out over the course of the study. The model simulations assumed al l the chlorpyrifos applied over the course of the study (one year) was applied as a single application event. Lastly, the model simulation also considered a worst case spray drift scenario. It is unclear if any drift reduction technologies (spray drift buffer, large droplet sizes, etc.) were utilized; however, spray drift reduction strategies ( i.e. , buffers) were not added to the chlorpyrifos labels until the Interim Registration Eligibility Decision in February 2002.



### Table 16. Surface Water Concentration Calculator Simulation Results Comparison with Orestimba Creek Surface Water Monitoring Data

Represented

Location Represented Crop Use Estimated Drinking Water Concentration 

### μ g/L (PCA adjusted concentration) Maximum

Detected Chlorpyrifos

Concentration (associated use) 1-in- 10 Year

Peak 1-in-10 Year

Annual Average 30 Year Average

1 Walnut 13.4 (2.68) 2.35 (0.47) 1.73 (0.35) 1.32 μ g/L (walnut, spray drift) June 11, 1997

(day 357)

2

Alfalfa 5.66-12.9 (1.13- 2.58) 0.69- 1.56 (0.14- 0.31) 0.61-1.39 (0.12- 0.28) 0.92 μ g/L (alfalfa, flood

irrigation) May 6, 1997

(day 325)

3 1.22 μ g/L (alfalfa, flood

irrigation) May 13, 1997

(day 331)

a. CA Almond, 1/2.2 lb a.i./A(assumes total annual application of chlorpyrifos was made to the single field on one day), June 10, aerial application [0.95; 0.135 (s pray drift assuming no buffer zones or droplet size restrictions)

b. CA Alfalfa, 1/2.2 lb a.i./A (assumes total annual applic ation of chlorpyrifos was made to the single field on one day) or 1/1.0 lb a.i./A (maximum currently registered application rate) , May 6, aerial application [0.95; 0.135 (spray drift assuming no buff er zones or droplet size restrictions)



### This analysis suggests that the model estimated concentrations of chlorpyrifos compare well with monitoring data when the model is parameterized to reflect the actual use and the PCA. Therefore, it is expected that the model estimated chlorpyrifos concentrations provide a reasonable upper bound of concentrations that may occur in the environment based on the modeled use and PCA applied. In addition, this dataset indicates sporadic detections and rapidl y fluctuating concentrations of chlorpyrifos, further

### 32 supporting the use of model EDWCs for deriving a reasonable upper bound estimation of chlorpyrifos exposure in drinking water.

The time series data were further investigated to identify bias factors. The approach employed was the same as that developed for atrazine. 39 

### The results are presented in the Table 17 . Bias factors were developed for each of the three sampling sites included in the study.

Based on this bias factor analysis, if monitoring data were available, for example, with a sample frequency of 21 days, a bias factor of 6.0 would be needed to adjust the measured concentration to obtain an upper bound estimate of the 21-day average exposure concentration. For the same sample frequency, a bias factor of 32 is needed to adjusted measured concentrations to capture an upper bound average daily

concentration.

Table 17. Bias Factor Values Developed based on 

### Orestimba Creek Surface Water Monitoring

Data

Annual Rolling Average

Maxima Sampling Frequency 7-day 14-day 21-day Average Bias Factor (range of bias factors) a Daily 4.35 (3.05

– 5.99) 12.0 (5.73

– 14.2) 14.3 (4.36

– 31.7) 21-day 2.08 (1.35

– 2.99) 3.34 (1.96

– 5.12) 3.06 (1.43

– 5.98)

a. Bias factors calculated based on the three different sampling sties included in the monitoring study.



### Washington State

Sampling focused on salmon-bearing streams in five different basins within Washington. Primarily weekly sampling was conducted during the pesticide use season; however, some daily sampling was also conducted. While the study did not specifically target chlorpyrifos use, nor did the report provide pesticide use information, some pesticide use surv ey data was obtained from WSDA. In addition, the report included information on the PCA for each of the basins included in the report.

The highest chlorpyrifos detections occurred within the Lower Yakima Agricultural Watershed ( 

### Table

18 ). The highest concentration (0.27 μ g/L) was detected in Spring Creek in 2007. Within the Lower Yakima Agricultural Watershed, use of chlorpyrifos includes: wine grapes (early dormant spray), tree fruits (early dormant spray), and mint (late season). Chlorpyrifos detection frequencies ranged from 3 to 68% for weekly sampling. Daily samples were collected (mid-May-June) for one year at one location. When daily and weekly sampling frequencies of detection were compared, daily sampling detection frequency was more than 25% higher.

### 33 Table 18. WSDA Monitoring Summary for Chlorpyrifos (2006-2011)

Location Spring Creek Sulphur Creek Wasteway Marion Drain

Maximum Detected Chlorpyrifos

Concentration 0.27 μ g/L 0.28 μ g/L 0.12 μ g/L

Sample Year a 2007 2009 2006 and 2007 Watershed Size (acres) 27,373 103,010 80,491

PCA b 50 42 66

Primary Crops (PCA) c Apples (4); Concord Grape (6); CRP (12%); Wine Grape (7); Hops d (3); Wheat (12) Apples (5); Corn (8 ); Concord Grape (7); Wine

Grape (4); Wheat (3 ) Apples (9); Corn (12); Concord Grape (3); Hops (13); Mint (6); Wheat (8)

a. The exact sampling date is not provided in the report.

b. Percent cropped area provided for each basin in the report; includes grass, hay, and CRP (Conservation Reserve Program)

c. Survey data from report

d. Not a registered chlorpyrifos use



### Combined with the chlorpyrifos us e information (type/timing of application), maximum label rates, and PCA, model simulations were completed for comparative purposes. The use scenarios used in model simulations for this analysis are provided in Table 19

, while chemical specific model input values are provided in 

### Table 10 . Note that a range of application dates was examined and the date that provided the highest concentration is reported. The re sults of this analysis are shown in Table 19 . In addition, the maximum detected concentrations were adjusted based on the maximum bias factor (2.99 based on a peak concentration and a sampling interval of 7 days) developed (presented in Table 17) for Orestimba Creek Surface Water Monitoring Data and are reported in Table 19.

### 34 Table 19. Surface Water Concentration Calculation Simulation Comparison with Washington State Department of Ecology and Agriculture Cooperative Surface Water Monitoring Program

Represented

Location Represented Crop Use Model Output PCA Corrected for

Total Cropland (PCA Corrected fo r Specific Crop a ) Maximum

Detected Chlorpyrifos

Concentration

(bias factor adjusted value) Absolute

Peak 1-in- 10

Year

Peak 1-in-10

Year

Annual Average 30 Year Average

Spring Creek Apples b 4.0

2.0 (0.16) 2.6

1.3 (0.10) 0.35

0.18 (0.01) 0.23

0.12 (0.01) 0.27 μ g/L (0.81) Grape c,d 4.3

2.2 (0.56) 1.7

0.85 (0.22) 0.25

0.13 (0.03) 0.15

0.08 (0.02)

Sulphur

Creek Wasteway Apples b 4.0

1.7 (0.20) 2.6

1.1 (0.13) 0.35

0.15 (0.02) 0.23

0.10 (0.01) 0.28 μ g/L (0.84) Grape c,d 4.3

1.8 (0.47) 1.7

0.71 (0.19) 0.25

0.11 (0.03) 0.15

0.06 (0.02)

Marion Drain Apples b 4.0

2.6 (0.36) 2.6

1.7 (0.23) 0.35

0.23 (0.03) 0.23

0.15 (0.02)

0.12 μ g/L (0.36) Grape 4.3

2.8

0.13 1.7

1.1

0.05 0.25

0.17

0.01 0.15

0.01

<0.01

Mint 6.1

4.0 (0.37) 3.0

2.0 (0.18) 0.36

0.24 (0.02) 0.22

0.15 (0.01)

a. PCA adjusted EDWCs reflect EDWCs if only the crop specified is treated within the watershed

b. ORApple, w24243 (Yakima), 1/2.0 lb a.i./a, dorman t 1/14 (dates examined: 1/1-3/31 based on emergence date in scenar io), ground application

c. CAGrape, w24243 (Yakima), 2/2.0 lb a.i./a, 7-da y application retreatment, dormant 1/13 (dates examined: 1/1-1/23 based on emergence date in scenario), ground application

d. Individual and combined PCA for concord and wine grapes.

e. ORMint, w24243 (Yakima), 1/2.0 lb a.i./a , 8/17 (8/1-9/31), ground application Current national spray drift restrictions were considered as part of this analysis.



### The estimated peak concentrations including bias fact or adjusted concentrations are generally higher but never greater than an order of magnitude higher than the maximum observed concentrations when a total cropland PCA is applied to the output values. The estimated concentrations may be higher than the measured values because 1) the sampling program mi ssed the peak concentration, 2) the monitored

locations were less vulnerable than the standar d “scenarios” used in the model simulations, and/or 3) the application rate and dates were different between the monitoring program and model simulations. Another

consideration is the site to site extr apolation of bias factors. At this time, the relative differences between the vulnerability of the sampling sites along Orestimba Creek and those sites included in this dataset are unknown. Therefore, the appropriateness of applying the bias factors calculated for the Orestimba Creek data across the board to a dataset like NAWQA, where the site vulnerability varies substantially, is

uncertain.

### 35 When individual crop PCAs are considered, the estimated peak concentrations in some cases

underestimate the measured maximum concentrations. Th is may be the result of multiple chlorpyrifos applications ( i.e. , multi-crop) contributing to the measured concentration.

This analysis demonstrates that the model estimated concentrations reasonably compare to measured concentrations. This suggests that if the maximum la beled rates were applied, as simulated using the SWCC, the model EDWCs provide a reasonable upper bound on the potential exposure and are not overly

conservative.

USGS National Water-Quality Assessment Program (NAWQA)

The NAWQA data were re-examined and the bias factor needed to result in a 21-day exceedance was calculated for each sampling site. Based on this analysis, the lowest bias factor calculated for a maximum 21-day average concentration to exceed the DWLOC was 8.2. The highest calculated bias factor for a 21- day average concentration based on a 21-day sampling interval was 6 based on the Orestimba Creek Surface Water Monitoring data. This would suggest that none of the sites exceeded the DWLOC. However, using a crude approximation of the sampling frequency (365 divided by the number of samples taken in a year), these sites had samples taken less frequently than every 21 days. Thus, a larger bias factor is likely needed to account for the limited sampling at these sites in order to estimate an upper bound 21-day average concentration. Therefore, it is likely that only of a few sampling sites included in the NAWQA dataset may have actually had a 21-day average concentration that exceeded the DWLOC. This suggests actual use of chlorpyrifos differs from the maximum rates included in the Master Use Summary Document

. This is consistent with the typical rate analysis completed by BEAD. 30,42



### The conclusion of the Model Simulations section of this document ( i.e. , chlorpyrifos and the corresponding chlorpyrifos-oxon concentrations vary substantially across the United States, and the exceedances of the DWLOC are highly localized) is underscored by this analysis. In addition, the relative differences between the vulnerability of the sampling sites along Orestimba Creek and those sites included in the NAWQA dataset are unknown. Therefore, the appropriateness of applying the bias factors calculated for the Orestimba Creek data across the board to a dataset like NAWQA, where the site vulnerability varies substantially, is uncertain.

Drinking Water Treatment

The preliminary DWA concluded that there are a number of different drinking water treatment processes that may impact the amount of chlorpyrifos and chlorpyrifos-oxon in drinking water and that the variation and combinations of processes used by the different tr eatment plant across the country make it difficult to estimate the exact amount of chlorpyrifos or chlorpyrifos-oxon that may be in drinking water on a national basis. In absence of evaluating each individual community drinking water treatment facility separately, the preliminary DWA recommended that all of the chlorpyrifos that enters a drinking water treatment facility be assumed to remain after treatmen t, as well as to assume that all the chlorpyrifos entering the facility was converted to chlorpyrif os-oxon during treatment. This was recommended to provide a bounding estimate of the potential exposure. It is likely that this approach overestimates the potential of exposure to chlorpyrifos and chlorpyrifos-oxon in drinking water distributed by some community drinking water systems, because processes like filtering with activated carbon, sedimentation, or water softening are not considered. Recent publica tions that examined the effectiveness of the use of activated carbon have shown that the source of activated carbon has a significant impact on the removal

42 Stebbins, K., Additional Typical Use Data for Chlorpyrifos

, January 11, 2012

### 36 efficiency of various organic compounds. Table 20 includes additional information on the breakdown of drinking water treatment processes used across the United States and supports the recommendations of the preliminary DWA, as well as empirical data on the percent removal of chlorpyrifos under such

conditions. 43



### All facilities distributing drinking water derived from surface water are required to filter and disinfect. 44


### The majority of treatment plants use chlorine as a disinfectant; however, less than 18% rely solely on chlorine. Generally, smaller community water systems rely on chlorination as their primary drinking water treatment method. Larger systems are more likely to use alternative disinfectant process to chlorine, such as chloramines when compared to smaller treatm ent plants. On average, 15% of treatment plants are not using chlorine. Water softening and chlorination ar e the most effective ways to reduce chlorpyrifos concentrations in surface source drinking water. However, use of chlorination results in the formation of chlorpyrifos-oxon.

To date, studies looking at the removal efficiency of chlorpyrifos across a range of treatment process have not looked at the formation of the chlorpyrifos-oxon. Moreover, no data are currently available on the percent chlorpyrifos-oxon reduction under typical drinking water treatment conditions. Water softening is expected to reduce the concentration of chlorpyrifos and chlorpyrifos-oxon due to rapid hydrolysis. While the USGS-EPA Pilot Reservoir Monitoring Program monitored raw and finished water, the correlation between sampling was not adequate, as finished wa ter sampling generally occurred before raw water sampling. The removal of chlorpyrifos or chlorpyrifos-oxon from other processes such as sedimentation and flocculation is also unknown. However, in general, these processes have not been shown to be effective treatment processes for removing pesticides.

One study 45 

### examined the impact of pesticide removal on a combination of potential drinking water treatment methods; however, this study did not assess the formation or dissipation of chlorpyrifos-oxon. The results of this study are consistent with other available data ( Table 20 ) that examined the reduction of chlorpyrifos under individual treatment processes. EFED is not aware of data for individual treatment plants on the impact of pesticide removal specific ally for chlorpyrifos and chlorpyrifos-oxon. EFED is also unaware of any monitoring data for chlorpyrifos or chlorpyrifos-oxon at the point of consumption ( i.e. , consumer tap water).

43 Chamberlain, E. Shi, H., Wang, T., Ma, Y., Fulmer, A., Adams. C. J Agric. Food Chem. 2012

, 60 , 354-363.

44 (54 FR 27486, June 29, 1989) (EPA, 1989b) 40 CFR Parts 141 and 142 Drinking Water; National Primary Drinking Water Regulations; Filtration, Disinfection ; Turbitity, Giardia lamblia, Viruses, Legionella, and Heterotrophic Bacteria; Final Rule

45 Ormand, M. P., Miguel, N., Claver, A., Mate sanz, J. M., Ovelleiro, J. L. Chemosphere, 2008

, 71 , 97-106.Table 20. Screening Analysis of Chlorpyrifos Degradation Under Typical Drinking Water Treatment Processes (surface water)Treatment MethodaFCMCAClO2MnO4-UVH2O2O3SofteningpH6.6pH8.6pH6.6pH8.6pH6.6pH8.6pH6.6pH8.6pH6.6pH8.6pH6.6pH8.6pH6.6pH8.6pH 12Percent Reductionb90.385.78.79.234.327.515.35.214.51.97.63.160.930.3100.0System PopulationCategoryPercentage of Plants Performing Each Treatment Practice for Surface Waterc100 or less98.4001.63.1--00101-500791.209.21.7--1.42.5501-3,30097.42.207.82.2--1.53.43,301-10,00080.813.71124.71.4--1.419.210,001-50,00080.514.88.732.91.3--1.216.950,001-100,00075.117.118.526.82.6--11.85.2100,001-500,00078.932.41426.34.7--15.811.8Over-500,00078.035.62.521.21.7--14.421.2a.Experimental time was representative of typical drinking water treatment conditionb.See footnote 43c.U.S. EPA Office of Water 2006 Community Water System Survey,May 2009(survey data)Chlorine (FC); Chlorine dioxide (ClO2); Chloramines (MCA); Lime/soda ash softener (assumed to be similar tohydrolysis at pH 12); Ultraviolet light(UV); Ozone (O3); Potassium permanganate(MnO4-)

### APPENDIX 1: Registered Use Clarification

In the preliminary DWA, several uncertainties relati ng to the registered uses of chlorpyrifos were identified, including:

1) Application restrictions provided on many chlorp yrifos labels are on a per season or crop cycle basis. For some crops there can be multiple seasons per year; however, the number of potential crops grown on the same field either as a result of multiple crops or crop rotations that may be treated with chlorpyrifos is not defined.

2) Some labels did not provide maximum single or annual application rates for chlorpyrifos or application retreatment intervals. This was common for trunk spray or basal drenches, which were reported as dilution factors.

3) Some labels restrict the amount of a specific chlorpyrifos formulation ( i.e. , products), but do not restrict total active ingredient (a.i.) that may be applied. Therefore, the use of multiple chlorpyrifos-containing formulations is possible.

In order to seek clarification of chlorpyrifos usage, the Agency compiled a Master Use Summary

Document ( ATTACHMENT 1) reflective of the use profile of all active product labels (as of January 2012). All currently registered labels were reevaluated to define the labeled uses. Currently, many of the product labels do not state a maximum number of applications allowed per year or crop season. Through discussions with the registrants, EFED believes that the detailed information on maximum application rates and use patterns given in the Master Use Summary Document will be implemented on all chlorpyrifos labels. The chlorpyrifos drinking water assessment is based on the information shown in the Master Use Summary Document . If for any reason the final chlorpyrifos labels contain higher application rates, higher numbers of applications, and/or shorter minimum retreatment intervals, the actual exposure to chlorpyrifos and chlorpyrifos-oxon may be greater than presented in this assessment.

Highlights of this effort are provided below.

1. For chlorpyrifos soil treatments to grape east of the continental divide, the single application rate was provided as a dilution factor. Based on a high density vineyard planting of nearly 3000 vines per acre [vines spaced 4 feet by 4 feet approximately 2756 vines (11-15ft 2 

### (3.75-4.4 ft) can be planted ( e.g. , 62719-301)] chlorpyrifos could be applied at an application rate of 33 lbs a.i./acre. While the calculated single application rate is co rrect, based on the dilution factor provided on chlorpyrifos labels and the potential vine density, the registrants indicated that this high application rate was not an intended use. As a result, the registrants agreed to update the labels to reflect a maximum single application rate of 2.25 lb a.i./A for all chlorpyrifos soil treatments on grape east of the continental divide.

2. Turf labels do not restrict the number of chlorpyrifos applications per year, nor provide a minimum retreatment interval. The registrants agreed to update the label to reflect a maximum single application rate of 3.76 lb a.i./A with no more than two applications per year. Therefore, 7.52 lb a.i./A would be the highest yearly application of chlorpyrifos permitted on turf.

3. The registrants have also agreed to update the labels to restrict the amount of chlorpyrifos that may be applied per year in terms of a.i./A by us e site rather than in terms per season or crop cycle.

### 39 4. The registrants have agreed to reduce the number of chlorpyrifos applications for some crops

such as tart cherries.

Although the current chlorpyrifos labels do not yet reflect the revisions agreed to by the registrants and

reflected in the Master Use Summary Document , the use summary document is being used to define the use profile for chlorpyrifos for the purposes of updating the registration review DWA for chlorpyrifos.

As mentioned above, the uncertainties associated with the use of chlorpyrifos use on grapes and turf have been resolved, and as a result, these crops use are no longer expected to result in the highest chlorpyrifos or chlorpyrifos-oxon concentrations as previous ly reported in the preliminary assessment.

Despite the on-going label clarification efforts, there are still a number of uncertainties associated with the current chlorpyrifos use scenarios included on the Master Use Summary Document

. ATTACHMENT

1 summarizes the remaining Master Use Summary Document uncertainties including assumptions made in the absence of information, if the use was assessed as part of the preliminary DWA, or this update, and the potential impact of the use relating to drinking water exposure. In general, reasonable assumptions could be made for agricultural crop use sites; however, for some use sites ( e.g. , commercial/institutional/ industrial premises/equipment), the use could not be reasonably assessed based on missing information, including single and yearly application rates. For these use sites, realistic assumptions could be made that result in drinking water exposure scenarios that ar e higher than those presented in this updated DWA.

### 40 APPENDIX 2: Spray Drift

In June of 2012, EPA finalized its evaluation of the potential risks from spray drift of chlorpyrifos. 46


### Results of this assessment indicated spray drift from application of chlorpyrifos using current (in 2012) label requirements generally resulted in risk estimat es of concern for locations immediately adjacent to treated fields. To address these risks, buff er zones and drift reduction technologies ( i.e. , larger droplet sizes) for sensitive sites 47 

### were implemented, in addition to rest ricting all aerial a pplications to 2.0 lb a.i./A or less except when chlorpyrifos is used to tr eat Asian citrus psyllid. In this situation, chlorpyrifos application may be applied at a rate of up to 2.3 lb a.i./A by aerial equipment.

The buffer zones and drift reduction technologies only apply to sensitive sites and do not protect aquatic environments; therefore, were not considered as part of the exposure modeling for drinking water in this update. Nevertheless, the aerial application rate restric tion of 2.0 lb a.i./A (2.3 lb a.i./A for Asian citrus psyllid) is an across the board restriction and; therefore, was considered as part of this update and is

reflected in the Chlorpyrifos Master Use Summary Document

.

Spray drift estimates were updated to reflect the most recent offsite deposition guidance 48,49 

### and considered the currently labeled buffer restrictions [ 25 ft. (ground), 50 ft. (air-blast), 150 ft. (aerial)] for aquatic water bodies. However, this updated analysis does not consider the court ordered spray drift buffers [60 ft. (ground and air-blast) and 300 ft. (aerial)] required for salmon bearing steams, as these buffers are only required in three states, California, Oregon, and Washington and are not required as part of the labeling under the Federal Insecticide, Fungicide, and Rodenticide Act.

46 Dawson, J., Bohaty, R., Mallampalli, N. Evaluation of the Potential Risks from Spray Drift and the Impact of Potential Risk Reduction Measures, June 20, 2012 PC 059101 DP 399483 and 399485.

47 Sensitive sites are areas frequented by non-occupational bystanders (especially children). These include residential lawns, pedestrian sidewalks, outdoor recreational areas su ch as school grounds, athletic fields, parks and all property associated with buildings occupied by humans for resident ial or commercial purposes. Sensitive sites include homes, farmworker housing, or other residential buildings, sch ools, daycare centers, nursing homes, and hospitals. Nonresidential agricultural buildings, including barns, livestock facilities, sheds, and outhouses are not included in this prohibition.

48 U.S. Environmental Protection Agency, Brady, D. Guidance on Modeling Offsite Deposition of Pesticides via Spray Drift for Ecological and Drinking Water Assessments, December 20, 2013

49 U.S. Environmental Protection Agency, White, K., Khan, F. , Peck, C., Corbin, M. Guidance on Modeling Offsite Deposition of Pesticides via Spray Drift for Ecological and Drinking Water Assessments, December 19, 2013

### 41 APPENDIX 3: Chlorpyrifos and Chlorpyrifos-oxon Volatility

While laboratory studies suggest that volatilization is not likely to play a significant role in the dissipation of chlorpyrifos in the environment, field data sugge st otherwise. Chlorpyrifos has been detected in air samples and as a result, EPA requested a field volatility study 50 

### as part of the data call-in requirements for the registration review of chlorpyrifos. EPA reviewed two field volatility studies (summarized below) that indicate volatilization of chlorpyrifos and/or chlorpyrifos-oxon from treated crops is a pathway of dissipation in the environment that may result in exposure to vapor phase or redeposited chlorpyrifos and chlorpyrifos-oxon downwind of a treated field. The two studies were conducted at rates much lower than the current maximum single broadcast application. While the absolute flux for chlorpyrifos observed in the potato study is higher than the alfalfa study, the flux profiles 51 

### are similar in both studies.

Study 1: Alfalfa

Dow AgroSciences (DAS) recently submitted a field volatility study that measured both vapor phase chlorpyrifos and chlorpyrifos-oxon in air samples following an application of a low VOC (volatile organic compounds or volatile organic chemicals) formulation 52,53,54 

### of chlorpyrifos to alfalfa. Approximately 30% of the applied chlorpyrifos was emitted from the treated field in the first 24 hours (28% considering chlorpyrifos only; 30% considerin g chlorpyrifos and chlorpyrifos-oxon combined). The flux profile for chlorpyrifos is similar to those generally observed for fumigants in that there is a peak emission shortly after application during the warmer pa rt of the day. The study measured chlorpyrifos for a period of 72 hours following application.

Study 2: Potato

A field volatility study published in the open literatu re was conducted with the application of a non-low VOC formulation of chlorpyrifos applied to potatoes. 55,56 

### This study only measured parent chlorpyrifos

50 EPA MRID 48883201: Direct Flux Measurement of Chlorpyrifos and Chlorpyrifos-Oxon Emissions Following Applications of Lorsban Adva nced Insecticide to Alfalfa ; Authors: Aaron Rotondaro and Patrick Havens; Sponsor: Dow AgroSciences LLC, 9330 Zionsville Road Indianapolis, IN 46268-1054, 2012

. 51 A flux profile is the emissions from a treated field over a defined period of time ( i.e. , an hourly time series of flux estimates during a period of measurement following application).

52 California's Department of Pesticide Regulation (Cal DPR) defines a low VOC pesticide formulation when the total emission potential (see footnote 53 ) is 25% or less (see footnote 54 ). The emission rate corresponds to total VOC emissions and not specially one component of the formulation ( i.e. , the active ingredient). EPA does not currently define low VOC pesticide formulations.

53 Emission potential is based on Thermogravimetric Analys is; Oros, D., Spurlock, F. California Department of Pesticide Regulation, ESTIMATING PESTICIDE PRODUCT VOLATILE ORGANIC COMPOUND OZONE

REACTIVITY. PART 1: SPECIATING TGA -BASED VOLATILE ORGANIC COMPUND EMISSIONS USING CONFIDENTIAL STATEMENTS OF FORMULA, January 27, 2011 http://www.cdpr.ca.gov/docs/emon/pubs/ehapreps/analysis_memos/2286_segawa.pdf

54 Proposed regulation can be found at: http://www.cd pr.ca.gov/docs/legbills/rulepkgs/12-001/text.pdf

55 EPA MRID 48998801: Volatilization of the Pesticides Chlorpyrif os and Fenpropimorph from a Potato Crop ; Authors: Minze Leistra, Johan H. Smelt, J. Hilbrand Weststrate, Frederik VanDenBerg, and Rene Aalderink; Sponsor: This work was carried out within the framew ork of the EU APECOP project Effective Approaches for Assessing the Predicted Environmental Concentrations of Pesticides (QLK4-CT-1999-01338) and of Research Program 416, Pesticides and the Environment, of the Du tch Ministry of Agriculture, Nature and Food Quality; Citation: Leistra, M; Smelt, J. H.; Weststrate, J. H.; Va n Den Berg, F; Aalderink, R. Environ. Sci. Technol. 2006

, 40 , 96-102.

56 Since the raw data for this study could not be obtained, th e flux rates could not be independently verified by EPA and, thus, evaluation of experimental details and associated data quality review of this study is not as rigorous as that

### 42 and did not measure concentrations of chlorpyrifos-oxon. Approximately 71% of the applied chlorpyrifos was estimated to volatilize from the treated field within 24 hours following application, assuming

continuous flux. 57



### While volatility has been observed to be a major route of dissipation of chlorpyrifos in the environment, the extent of deposition following volatilization and the area of deposit off a treated field is unknown. As a conservative approach, all the applied chlorpyrifos is assumed to be available for runoff, spray drift, and erosion in this update. The reported EDWCs may be hi gher than concentrations that would be found in the environment because volatilization is not accounted for in model simulations. Volatility is the likely reason chlorpyrifos is detected in remote regions or in precipitation collected from locations far from potential applications sites. In addition, in some cases chlorpyrifos monitoring is conducted from irrigation canals which discharge to streams and rivers and chlorpyrifos is not observed in the irrigation water yet is samples of river water reveal concentrations of chlorpyrifos. This may be the result of volatilization followed by redeposition.

associated with the alfalfa study. The results from this study are presented in this assessment to provide another line of evidence of the potential volatility of chlorpyrifos, as demonstrated in the registrant submitted study, and to help describe the potential variability in chlorpyrifos flux rates due to different study conditions ( e.g. , crop canopy, formulation, and weather).

57 Sampling did not occur at night; therefore, in order to de velop a 24 hour flux profile. EPA developed a flux rate for the missing sampling periods by averaging the flux rate pr ior to and after the time period when sample collection

did not occur.

### 43 APPENDIX 4: NAFTA Kinetic Analysis

Aerobic Soil Metabolism

### 44

### 45

### 46

### 47 Anaerobic Aquatic Metabolism

### 48 Anaerobic Soil Metabolism

### 1

Attachment 1 . Chlorpyrifos Use Summary

Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1

(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

AGRICULT

URAL FARM

PREMISES

Livestock housing and holding areas (such as hog barns, empty chicken houses, dairy areas, milkrooms, calf hutches, calving pens and parlors).  Indoor general surface spray backpack

sprayer; high

and low sprayer (pressure or volume) 0.075 lb a.i./

1000 ft sq

1.2 EC, ME [14.4]

NS NA 12 NA NA NS NS Only permitted

for use in poultry houses

ALFALFA

 At plant groundboom 1.0

G 1 .0 1.0 [1]

NS 1 21 24 [10]

N S Missouri

only Lower PHI

permitted for

EC rates 0.33 lb a.i./A (7 d) and

0.67 lb a.i./A (14 d) e.g. Reg.

No. 62719

- 591

Stand is in production 3

- 5 years. Planted 1⁄4” to 1⁄2” deep.

 Foliar aerial or ground/ broadcast, chemigation 1.0

EC [4.0]

NS 4.0 [4]

NS 4 21 24 10 Lower PHI permitted for

EC rates 0.33 lb a.i./A (7 d) and

### 2 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

0.67 lb a.i./A (14 d) e.g. , Reg.

No. 62719

- 591

Multiple harvests (or cuttings) per year when used

for feed/fodder

and 1 harvest per year when grown for seed. Cuttings occur about every 30 days. Only 1 crop cycle per year but up to 9 cuttings, varies by geography.

Total 1.0 5.0 5.0 [5]

NS 5 21 24 [10]

NS Represents

Missouri

scenario

otherwise 4.0 lb a.i./A per is

max. ALMOND

 dormant/ delayed

dormant ; broadcast aircraft, airblast 2.0 WDG, WP 2.0 NA 1 NA NA 24 10 Restricted

use in

California.

 foliar ; aircraft, airblast 2.0 6.0 NA 3 NA 14 10

### 3 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

broadcast WDG,WP

 pre

- plant,

foliar;

trunk spray/drenc h or pre

- plant dip handheld,

backpack, drench/dip, handgun, and low pressure

hand wand 2.5

( 3.0/100 gal )

WDG 2.5 NA 1 NA 14 NS

 Dormant/

delayed dormant; foliar;

orchard

floors

broadcast ground boom,

handgun, chemigation 4.0

EC* 4.0 NA 2 NA 14 10 Restricted

use in

California. Only one

dormant application

can be made.

Total

-- 4.0 14.5 NA 7 NA 14 NS Excludes

nursery applications (See general “Fruits” listing)

APPLE

 dormant/ delayed

dormant ; broadcast aircraft, airblast 2.0

EC

2.0

WDG

1.5

WP 2 2 .0 1 1 NA 24/

4 d 10d Reflects spray drift mitigation

measures.

 pre

- plant,

foliar;

trunk spray/drenc h or pre

- plant dip ; handheld,

backpack, drench/dip, handgun, and low pressure

hand wand 1.5

( 1.5 lb ai/100 gal )

WDG 1. 5 NA 1 1 28 4d NS Use permitted in

states east of

the Rockies
except Mississippi.

### 4 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

ground

Total 2.0 3 .5 2

ASPARAGUS  Foliar, pre

harvest;

broadcast aircraft, ground

boom 1.0

EC, WDG 1.0 1.0 1 1 1 24 10

 Postharvest,

broadcast aircraft, ground

boom 1.0

EC, WDG 2.0 2.0 2 1 1 24 10

granular soil

band treatment ground boom 1.5

G 3.0 3.0 2 2 180 24 [10]

NS Permitted in California, the Midwest,

and the

Pacific

Northwest

19713

- 505,

19713

- 521,

5481

- 525,

62719

- 34,

83222

- 34 Do not apply

more than 3 .0 lb

a.i./A between

harvests.

Total 1.5

G 3.0 G

2.0 3.0 G

2.0 3 3 1 24 10

BEANS

 Preplant;

Seed

treatment Seed Treatment 0.0 16

- 0. 348

0.0 00 798 lb

ai/ lb seed

M E

0.01 3

- 0

. 272

0. 00 0625 lb

ai /lb seed NS [0.348]

NS NS [1]

NS NS NS NS ME is SLN only for ID I talics highlight

the range of application rates depending

on the number of seeds per lb

and the number

### 5 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

WP

0.0 12

- 0. 253

0.0 00 58 lb

ai /lb seed

EC of seeds planted

per acre. Seeding rate

information provide by

BEAD. 4

BEEF/RANGE/

FEEDER

CATTLE (MEAT)/

DAIRY CATTLE (NON

- LACTATING) Summer, late fall, spring; impregnated collar/tag Animal

treatment (ear tag) 0.0066

lb/animal [ 0.0099

]

NS NA 3 NA NS NS NS Reg. No.

39039

- 6 Cattle ear tags

are assumed to

last 4

- 6 months

Two tags per
animal at

0.0033 lb a.i./tag in the

summer and

one tag per
animal at

0.0033 lb a.i./A.

BEETS (UNSPECIFIED;

TABLE OR SUGAR)

“grown for seed”  At plant, soil

band

treatment Ground boom 1.0

EC NS 1 NS 1 24 Allowed in Oregon

Court

ordered

buffer of 60 ft for ground chlorpyrifos application is required

for “ affected waterways”. Minimum

Incorporation: 2

inches

### 6 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

 Preplant, soil

incorporated

treatment Broadcast/

ground boom 1.9

EC NS

(2.8 ID) NS 1 NS Allowed in Oregon and

Idaho OR

- 09007;

62719

- 591

ID

- 090002;

62719

- 591

Total 1.9 NS NS NS NS 24 One or the other type of application.

SUGAR BEETS  Preplant, soil incorporated

treatment Broadcast/

ground boom 1.0

EC

2.0

G 3 .0 2.0 1 1 NA 24 10 Minimum Incorporation: 1

inch

 At plant, soil

band

treatment Broadcast/

ground boom 1.0

EC, WDG

2.0

G 3 .0 2.0 1 1 30 24 10

 Postplant,

soil band Broadcast/

ground boom 2.0

G 3 .0 2 .0 1 1 30 24 10

 Post

-

emergence band

treatment;
broadcast Broadcast/

ground boom 1.0

EC, WDG 3 .0 1.0 3 1 30 24 10

 broadcast Aircraft, ground boom, chemigation 1.0

EC, WDG 3 .0 1.0 3 1 30 24 10 EC is not for

use in MS

Total 1.0

EC

2.0

G 4.0 [4.0]

NS 3 [3]

NS 30 24 10 One granular application at

2.0 a.i./A and two liquid applications at 1.0 a.i./A per

### 7 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

year. Also assumed per crop cycle.

CARROT

Grown for Seed (INCLUDING TOPS)

 Foliar pre

- bloom

broadcast aircraft, ground

boom 0.94

EC 0.94 1 1 1 7 24 NA Oregon and Washington

Court

ordered

buffer of 60

ft for ground

and 300 ft

for aerial application is required
for “ affected waterways”. OR090011

SLN Expires:

12/31/2018

WA090011

SNL Expires:

12/31/201 6

Carrots take

two years to produce seed.

All commercial production of

the carrot (vegetable) takes place in the first year when the plant

is nowhere near blooming.

CHERRIES

 dormant/ delayed

dormant ; broadcast aircraft, airblast 2.0 WDG, EC

1.5

WP 2.0 NA 1 NA NS 24 10

 foliar ;

broadcast airblast 4.0

EC 10.0 NA 5 NA 14 24 10 Tart cherry only

aircraft 2.0 Reflect s spray drift mitigation

### 8 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

 Foliar, post

harvest;

trunk spray/drenc

h handheld,

backpack, drench/dip, handgun, and low pressure

hand wand 2.5

( 3.0/100 gal ) WDG, EC 2.5 NA 1 NA 2 24 [10]

NS Only s ome

labels specify a

10 d MRI.

Total --

4.0 4.5 (sweet)

1 4 .5 (tart only) 6 Excludes

nursery applications (See general “Fruits” listing)

The foliar

app lications only apply to tart cherries,

thus , sweet cherry scenarios ( e.g. , Pacific

NW ) annual application rate

would be 4.5 lb

total a

. i

. /year.

CHRISTMAS

TREE

PLANTATIONS  foliar ; broadcast helicopter,

orchard blast 1.0

EC, WDG, WP 3.0 NA 3 NA [0]

NS 24 7 Aerial

applications

via helicopter are only permitted in Washington and Oregon.

### 9 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

 post harvest;

Stump

Treatment handheld,

backpack, drench/dip, handgun, and low pressure

hand wand 2.5

( 3.0/100 gal ) EC, WDG 2.5 NA 1 NA NA 7

Total 2.5 5.5 4

CITRUS

 foliar ; broadcast airblast , ground

boom 6.0

WP, WSP, EC 7.5 NA 2 NA 35 (21

for

low

rate s) 5d 30

(10

for

low

rates ) 6.0 lb a.i. /A is only permitted in

California

and Arizona.

The max single rate in

other states

is restricted

to 4 lb a.i./A.

 aircraft 2.3 WP, WSP, EC 21 5 10 Florida, California,

and potentially

Texas Aerial

application used

to control psyllid, the

vector for citrus greening.

Reflect s spray drift mitigation

 foliar;

orchard

floors

broadcast ground boom,

chemigation, handheld, backpack, drench/dip, handgun, and 1.0

G*, WSP, EC 3.0 NA 3 NA 28 24/

5 d 10

### 10 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

low pressure

hand wand

Total

-- 6.0 10.5 5 Registered labels permit

both foliar and soil applications

in the same

orchard.

Total excludes

nursery applications (See general “Fruits” listing )

CLOVER (GROWN FOR SEED)  Preplant Ground boom 1.9

EC 1.9 1.9 1 1 NS 24 NA Use only permitted in Oregon. OR

- 0900100;

master label:

62719

- 591

 Post

- Plant

Foliar aircraft and

ground boom Either a preplant or post plant application is

allowed.

COLE CROPS (EXCLUDES

CAULIFLOWE

R AND  Preplant, soil incorporated

treatment Ground boom

2.0 EC, WDG, G 4.0 2.0 2 1

30 24 10 Min. incorporation:

2 inches

BRUSSELS SPROUTS)  At plant, soil

band

treatment Ground boom 1 One granular application permitted per

year.  Post plant Ground boom 1

### 11 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

 Foliar

Established Plantings,

soil sidedress

treatment Ground boom 1

 Foliar,

broadcast Aircraft, ground

boom, chemigation 1.0

EC, WDG, WP 4.0 3.0 4 3 21 10 Multiple crops

per year are possible in

some locations.

Total 8.0 5 6 4 Some labels

restrict the yearly application rate

to 3 lb a.i./A.

The maximum

number of crops per year is 2

.

BRUSSELS

SPROUTS  At plant, soil

band

treatment Ground boom

2.0 EC; G 2.0 [2.0]

NS

2 1 21 24 10  Preplant, soil

incorporated

treatment Ground boom Minimum incorporation is

2 inches

 Postplant,

soil application Ground boom 2.25 EC, G 2.25 [2.25]

NS

 Foliar

broadcast Aircraft,

Ground boom 1.0

EC [5.3]

NS 3.0 NS 3 10 83222

- 20,

84930

- 7,

86363

- 3 specify a 7 day MRI.

All other labels

### 12 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

specify a 10 day

MRI.

The PHI stated

84930

- 7 is conflicting [p. 4 (21 days and p. 19 (30 days)]

Total 2.3 5.3 NS 21 24 7 Assume one application of either at plant, preplant, or postplant

followed with

additional foliar applications.

CAULI

- FLOWER  At plant, soil

band

treatment Ground boom 2.0

EC

2.3

G 2.0

EC

2 .25

G NS [1]

NS 1 21

3d 10 Only one granular application.

 Preplant, soil

incorporated

treatment Ground boom 2.3

G

2.0

EC 2.3 NS [1]

NS 1 30,

EC,

21

G Minimum incorporation is

2 inches

 Postplant,

soil application Ground boom

 Foliar

broadcast aircraft, ground

boom 1.0

EC [5.3]

NS 3.0 NS 3 21 10

Total 2.3 5.3 [5.3]

NS NS [4]

NS 21 24 10 Assume one application at either plant, preplant, or

### 13 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

postplant

followed with

additional foliar applications.

COMMERCIAL

/INSTITUTION

- AL/

INDUSTRIAL

PREMISES/ EQUIP. (INDOOR)

Non

- food areas of manufacturing, industrial, and food processing plants; warehouses; ship holds; railroad

boxcars. Broadcast Product

Container 0.4373 lb

a.i./100 sq ft

190.5

G NS NA NS NA NA NS NS For treatment of

fire ants

Crack and

Crevice/Void Sprayer/

Injection 0.0625 lb

a.i./1000 sq ft

2.7

ME NS NA NS NA NA NS NS 499

- 419

Crack and Crevice/Spot Sprayer/

Injection 0.0424 lb/gal

ME NS NA NS NA NA NS 7

COMMERCIAL

/INSTITUTION

AL

/INDUSTRIAL PREMISES/EQ

UIP. (OUTDOOR)

Outdoor

commercial use

around non

- food

areas of manufact

- uring, industrial, Soil

broadcast

Low and High

Pressure, Backpack, Handgun Sprayers 0.0247 lb

a.i./1000 sq ft

1.1

ME NS NA NS NA NA NS NS

Directed

spray 0.1132 lb a.i./1000 sq ft

4.9

ME NS NA NS NA NA NS NS Specific to:

Inside and

outside dumpsters and

other trash holding containers, trash

corrals and

### 14 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

and food processing plants; warehouses; ship holds; railroad

boxcars other trash
storage areas.

Crack and

Crevice/void/ general

outdoor 0.0424 lb/gal

ME NS NA NS NA NA NS 7

CONIFERS

AND

DECIDUOUS TREES;  ? foliar ; broadcast Ground boom 1.0

EC 3 NA 6 NA 7 24 7

PLANTATION,

NURSERY  ? foliar; stump

treatment backpack,

drencher, low pressure hand

wand 0.3

EC 0.3 NA 1 NA 7 24 7

Total 1.0 3 NA 6 NA 7 24 7 The total

number of applications

assumed is

either 3 foliar applications or

2 foliar applications with one stump

treatment.

CORN (ALL)  Preplant ground/ soil incorporated

conservation tillage, in furrow, broadcast, chemigation, 3.0

EC

2.0

G 3.0 3.0 NS 3 NA 24/

5

EC 10 19713

- 520,

19713

- 599,

33658

- 26,

34704

- 857,

72693

- 11,

83222

- 20

### 15 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

soil band The minimum incorporation depth is 2

inches.

soil incorporated

aerial

conservation tillage 2.0

EC, G

 ground/

conservation tillage, in furrow, broadcast, chemigation,

soil band 1.0

EC

2.0

G 3.0 3.0 NS 3 21 10 19713

- 520

 Storage or

preplant seed

treatment Seed treatment 0.0 01

- 0.0 21

0. 00 0625 lb

a.i./ lb seed

WP

0.1

- 1.9

0.058 lb a.i./ lb

seed

FC [?]

NS [1.9]

NS [?]

NS 1 NS NS NS Italics highlight the range of application rates depending

on the number of seeds per lb

and the number of seeds planted

per acre. Seeding rate

information provide by

BEAD. 4

 At plant soil incorporated, 2.0 [?]

NS 3.0 [?]

NS 3 21 24 10

### 16 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

conservation tillage G

 Post

emergence Aerial or

ground, broadcast, chemigation 1.5

EC

1.0

WDG NS 3.0 NS 3 21

24/

5d (EC 10 A brush on max single rate is permitted at 1.0 lb ai/a (72693

- 11)

 Foliar Aerial or ground/ broadcast, granule, seed

and chemigation 1.5

EC 3.0 3.0 NS 3 21 10

Total 3.0 8.1 8.1 NS 4 21 10 Two granular applications are

allowed with a

maximum single rate of

1.0 lb a.i./A or one granular application at 2

lb a.i./A.

Total with seed

treatment
PHI: 21 d

except
Delaware and Florida (7 d)

COTTON  Storage or preplant seed

treatment Seed treatment 0.8

- 2.2

0. 00 116 lb/lb

seed [2.2]

NS [2.2]

NS [1]

NS 1 NS NS NS 264

- 9 32

Rates in italics highlight the

### 17 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

EC potential range of application rates depending

on the number of seeds per lb

and the number of seeds planted

per acre. Seeding rate

information provide by

BEAD. 2

 Foliar aerial, chemigation, ground boom 1.0

EC, WDGP 3 3.0 3 3 14 24 10 Except MS

Total 1 .0 3.2 3.2 3 3 14 24 10 1.6 lb a.i./A is max single rate (seed treatment)

Total with seed

treatment
1 c rop c ycle per

year assumed

CRANBERRY  Foliar aircraft, ground

boom/

broadcast and chemigation 1.5

EC, WDG 3.0 NA 2 NA 60 24 10 Not for use

in Mississippi. Do not apply to

bogs when

flooded.

CUCUMBER  Storage or preplant seed

treatment Commercial

seed treatment 0.4

0.0 00 5 8 lb/lb

seed

EC NS 0.1 2 1 NS NS NS Seeding rate

information provide by

BEAD. 2

264

- 932,

### 18 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

62719

- 221,

CA040004 Per registrant 2 CCs per year

FIGS  dormant/ delayed

dormant ; soil application ground boom 2.0 WDG, EC 2.0 NA 1 NA 217 4 d NS Use is

restricted to

California only. Incorporation to

3 inches is suggested but not required following application.

FILBERTS/

HAZELNUT  dormant/ delayed

dormant ; broadcast aircraft, airblast 2.0

WP 2.0 NA 1 NA 14

24 10

 foliar ;

broadcast aircraft, airblast 2.0 WDG, WP, EC 6.0 NA 3 NA 14 10 Some labels specify a

retreatment
interval of 10 days.

Total 2.0 6.0 NS 3.0 NA 14 24 10 Excludes

nursery applications (See general “Fruits” listing )

FOOD

PROCESSING

PLANT

PREMISES (NONFOOD CONTACT) When needed, crack

and crevice

treatment,
spot

treatment 0.0424 lb/ gal

ME NS NA NS NA NA NS 7 53883

- 264,

84575

- 3 Spot Treatment:

Do not exceed two square feet

per individual

spot

.

### 19 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

FOREST

PLANTINGS (REFORESTAT

ION PROGRAMS) (TREE FARMS,

TREE  Foliar,

broadcast ground boom 1.0

EC 6.0 NA 6 NA

24 7

PLANTATION, ETC.)  Foliar, stump

treatment direct spray,

drencher 0.34

EC 6.0 NA [18]

NS NA 7

FOREST

TREES (SOFTWOODS, CONIFERS)  Foliar,

broadcast ground boom,

drencher 0.6 1

EC 3.6 NA NS NA 24 7

 Foliar, stump

treatment direct spray [3.6]

2.4 lb a.i./100 gal

EC 3.6 NA NS NA 7 Application rate is provided as a

dilution factor.

FRUITS &

NUTS

Non

- bearing (not

to bear fruit within 1 year)

fruit trees in

nurseries (includes: almonds, citrus, filbert, apple, cherry, nectarine, peach, pear, plum, prune).  Foliar

- Non

- bearing

nursery broadcast High/low

volume spay/

hand held sprayer/power

sprayer 4.0

EC 4.0 NA NS NA 14 NS 7 For nectarines and peaches,

the use is

restricted to one application of

no more than 3 lb a.i./A per cc. For apples, the

max rate is 2 lb a.i./A per c rop

c ycle and the

use is restricted to 1 application (either canopy

### 20 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

or trunk drench)

per year. Example label,

62719

- 254

 Foliar

- Non

-

bearing nursery trunk

drench drencher, high

and low

pressure sprayer 2 .0

WDG 2 .0 NA NS 1 14 7

Total 4.0 6.0 Maximum Single Rates: 3.0 (nectarines and peaches)

2.0 (apples)

Maximum Yearly Rates: 3.0 (nectarines and peaches) 2.0 (apples)

GINSENG (MEDCINAL)

 Preplant,

post

- emergence Ground, soil

broadcast 2.0

G 2.0 NA 1 NA 365 24 NA Permitted in Michigan

and

Wisconsin MI110006,WI1

10003)

Minimum incorporation: 4

inches Application

should be followed by

rainfall or

overhead watering.

Valid until June 29, 2016.

### 21 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

GOLF COURSE

TURF When needed, soil

broadcast/

spot

treatment Ground, low

pressure 1.0

EC 2.0 NA 2 NA

24 NS

Foliar, broadcast, Ground boom,

handgun, low pressure and backpack 1.0

EC, G, B

2.0 NA 2 NA NS Chemigation

not allowed for

the EC

formulation. Tractor drawn spreader, push type spreader, belly grinder 1.0

G [24
]

NS 7

Mound

treatment Granule

applicator 1.0

G 2.0 NS 2 NS NS 7

Total 2.0 2.0 NA 2 NA NS NS

GRAPES

 Dormant/ Delayed

Dormant (pre

- bloom) Ground boom,

broadcast,

drench high/low spray

volume 1.0

WDG, EC 1.0 1 1 NA 35

24 NS East of the

continental divide only. Do not use in

conjunction

with soil

surface applications for grape borer

control.

 2.0

EC 2.0 1 1 N A 35 Permitted in Colorado, Idaho, and Washington CO080008,

ID090004,

WA090002

Master label:

62719

- 591

 Foliar Ground/ 2.25 2.25 1 1 NA 35 NS Permitted

### 22 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

broadcast, basal spray and drench (soil treatment) EC east of the

continental

divide.

 1.0

EC 3.0 3 3 NA 35 NS California CA080010

 Postharvest,

dormant/ delayed

dormant Ground boom,

broadcast 2.0

EC 2.0 1 1 NA NS NS California CA080009

Total 2.25 2.25 1 35 24 N S Permitted

east of the

continental

divide.

2.0 5.0 4 NS NS California

GRASS

FORAGE/

FODDER/HAY  Foliar,

broadcast Aircraft, ground

boom, chemigation 1.0

EC 3.0 NA 3 NA NS 24 Permitted in Nevada, Oregon, Washington,

and Idaho NV080004,

NV940002, OR090009, WA090010,

ID090003

GREENHOUSE

 early evening, aerosol, fog or fumigation Total release

fogger 0.029

0.0066 lb a.i./1000 sq. ft

PL NS NA NS NA NS NS 2

HOUSEHOLD/

DOMESTIC

DWELLINGS

INDOOR

PREMISES  When needed Bait station 0.0003 lb/bait

station NS NA NS NA NA NS NS 9688

- 67

HYBRID

COTTONWOO  Foliar, dormant, High volume

(dilute) 1.9

EC [2.0]

NS 6.0 [1]

NS 3 24 7 Washington WA090004

### 23 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

D/ POPLAR

PLANTATIONS delayed dormant;

broadcast Low volume

(concentrate) Energy wood plantations may

be harvested as often as every

2

- 3 y ea rs; pulpwood 5

- 10

y ea rs; and saw

timber 15

- 20

y ea rs. (Arkansas production guide). In Washington the crop takes 2

- 8

y ea rs LEGUME

VEGETABLES  Preplant, soil

treatment Ground boom 1.0 EC, WDG 1.0 NA 1 NA N S

24 NA No MRI

because application only

once a year  At planting,

soil treatment Ground boom 1.0 EC, WDG 1.0 NA 1 NA N S NA

Total 1.0 1.0 NA 1 NA NS 24 NS Assumed either a preplant or an at plant

treatment.

MINT/

PEPPERMINT/

SPEARMINT  Preplant soil incorporated Aerial or

ground/

broadcast 2.0

EC, WDG [2.0]

NS 2.0 [1]

NS 1 90 24 NA No use in Mississippi. 19713

- 599,

33658

- 26,

34704

- 857,

67760

- 28,

84229

- 25,

84930

- 7,

OR940027

### 24 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

MRI NA due to

once per c rop

c ycle application

 Post

-

emergence, Postharvest,

Foliar Chemigation,

ground/ airblast 2.0

EC 2 .0 2 .0 [1]

NS 2 90 NS No use in Mississippi. Postharvest

application

retreatment not specified on

some labels.

Total 2.0 4.0 4.0 2.0 3 90 24 NS Labels allow one growing

season application including pre

- plant and one
post

- harvest application per

season.

MOSQUITO CONTROL;

HOUSEHOLD/

DOMESTIC

DWELLINGS

OUTDOOR PREMISES;

RECREATION

AL AREAS  When needed;

broadcast Ultra low

volume air and ground 0.01

EC 0.26 NA 26 NS NA NS 24 h In Florida: Do not apply by aircraft

unless approved by

the Florida Dept of Ag. Aerial

applications may be made at

altitudes ranging from

75

- 300 ft (see

labels for specific s). For use by federal, state,

tribal or local

government officials or by

### 25 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

persons certified in the appropriate

category or authorized by

the state or

tribal lead regulatory

agency. NECTARINE

 dormant/ delayed

dormant

broadcast airblast,

handgun 3.0

WDG, EC

3.0 NA 1 NA NS

24/

4d 10 83222

- 20 others

at 2 lb a

. i

. /a

Aircraft 2.0

WDG, EC Updated to reflect spray drift mitigation.

 pre

- plant,

foliar;

trunk spray/drenc h or pre

- plant dip Handgun, low

pressure backpack, dip 2.5

( 3.0/100 gal ) WDG, EC 2.5 NA 1 NA 14 5 There is no application

retreatment
interval specified on

some of the

label. The application rate is provided as a

dilution factor.

Total 3.0 5.5 NA 2 NA Some labels

limit the

amount a.i./A

per year. Multiple types of applications

can occur such

### 26 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

as preplant,

trunk drench and dormant, delayed

dormant applications.

Excludes

nursery applications (See general “Fruits” listing)

NONAGRICUL

TURAL

OUTDOOR

BUILDINGS/ST

RUCTURES

to and around

outside surfaces

of nonresidential buildings and

structures.
Permitted areas of

use include fences, pre

- construction foundations, refuse dumps, outside of walls,

and other areas where pests

congregate or Outdoor general

surf ace/ Band (may be

better if

called perimeter) Ground s prayer/

band sprayer 1.0

EC NS NA NS NA NA NS NS

### 27 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

have been seen

NURSERY

- STOCK : : Ornamental nursery stock annuals, perennials and woody plants being grown in the field, in ball and burlap or in

containers

outdoor and in greenhouses Dormant/ Delayed

Dormant high spray 3.0

EC 3.0 NA 1 NA 24 NS

Preplant Ground boom,

soil incorporated 4.0

EC, WP NS NA NS NA

foliar, soil

directed T ractor drawn

spreader, push type spreader, belly grinder, gravity fed backpack,

spoon 1.1

G

Total 4.0 CBD 3

ONIONS  Post plant (seeding)

Broadcast Ground boom 1.0

EC 1.0

NS 2

NS 60 24 NS

 At plant, soil

drench or basal spray Ground boom 1.0 EC, WDG, G 1.0 1 2 inch incorporation

### 28 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

Total 2.0 2.0 2 60 24 NS

ORNAMENTAL

AND/OR SHADE TREES,

HERBACEOUS

PLANTS  Foliar

broadcast Ground boom,

air blast, handgun, low and high pressure hand

wands 2.0

EC, WP

1.0 G, B 2 .0 NA [2]

NS NA NS

24 NS Some labels

include a MRI of 7 days.

 Dormant

/Delayed

Dormant Handgun, low

pressure and backpack 3.0

EC 3.0 NA 1 NA NS 7 Low volume spray permitted

for concentrated

solutions and

lower rates.

ORNAMENTAL

LAWNS AND TURF, SOD FARMS (TURF)  When needed, broadcast, soil or spot

treatment ground boom

(WP only), high pressure hand

wand 3.76

EC, WP 7.52 NA 2 NA NS 24 NS

 NS Tractor drawn spreader, push type spreader, belly grinder 1.0

B 2.0 NA 2 NA NS 24 NS Bait is used for

fire ant control.

ORNAMENTAL

NON

- FLOWERING

PLANTS  Foliar, broadcast,

soil drench Chemigation,

ground boom, low and high

pressure handwand, handgun, backpack

sprayer, sprinkling can 0.007/gal

ME NS NA 12 NA NA 24 NS Application rate provided as a

dilution factor.

Restricted

use

— occupational only

ORNAMENTAL Foliar Ground boom, 2.0 2 .0 NA [1] NA NS 24 NS Several labels

### 29 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

WOODY

SHRUBS AND

VINES broadcast air blast, handgun, low and high

pressure

sprayer, backpack EC, WDG

0.01 lb/gal

EC 0.01

lb/gal NS do not restrict the application

rate in lb a.i./A. Examples

include 16.5

lb/100 gal (228

- 625) and 1.0 lb/100 gal (829

- 280).

Dormant/ delayed

dormant 1.0

EC 0.005 lb/gal

EC 1 .0 NA [1]

NS NA

Preharvest Tractor drawn

spreader, push type spreader, belly grinder 6.0

G 6 .0 NA [1]

NS NA

Preplant, potted,

bailed

- and burlapped,

containerized groundboom,

handgun, low and high

pressure

sprayer, backpack,

drench 1.0

EC NS 1 NS 1

Pretransplant groundboom 4.0

WP [48 .0 ]

NS 4 12 4

Total 6.0

G

4.0

WP CBD CBD

PEACH  dormant/ airblast 3.0 3.0 NA 1 NA 10 24/ NS 83222

- 20 (all

### 30 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

delayed

dormant

broadcast EC

2.0

WDG 4d other labels

restrict to 2 lb ai/a)

aircraft, 2.0

EC

2.0

WDG NS Updated to reflect spray drift mitigation.

 Post

- harvest

broadcast airblast 2.5 ( 3.0/100 gal )

EC 2.5

NA 1 NA NA NS Permitted in Georgia and

South

Carolina GA0400001,

SC040001 SLN Expires:

aircraft 2.0

( 3.0/100 gal )

EC 2.0 GA0400001,

SC040001 SLN Expires: Updated to reflect spray drift mitigation

 pre

- plant,

foliar;

trunk spray/drenc h or pre

- plant dip ; ground handheld,

backpack, drench/dip, handgun, and low pressure

hand wand 2.5

( 3.0/100 gal )

WDG 2.5 NA 1 NA 14 5 NS Some labels do not specify

minimum

retreatment
interval.

Total 3.0 5.5 NA 3 NA NA 24 NS It is possible that multiple types of applications can

occur such as soil, foliar and/or post

- harvest and 3.0 8.0 NA 3 NA NA 24 NS Permitted in Georgia and

South

Carolina

### 31 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

dormant/ delayed

dormant applications.

Excludes

nursery applications (See general “Fruits” listing)

PEANUT

 Preplant

Aerial or ground/

broadcast 2.0

EC, WDG [4.0]

NS 4.0 [2]

NS 2 NA 24 10 Do not apply

aerial in Mississippi Assumes one

crop cycle per

year.  At plant,

postplant 4.0

G [4.0]

NS 4.0 2 2 21 24 10

 At pegging 2.0

G EC, WDG [4.0]

NS 4.0 2 [2]

NS 21 24 10

Total 4.0

G

2.0 EC, WDG 4 .0 4.0 2 2 10 24 10

PEAR

 dormant/ delayed

dormant

broadcast aircraft, airblast 2.0 WDG, EC 2.0 NA 1 NA NA 24 NA Restricted

use in

California. 83222

- 20

allows 3.0 lb

a.i./ A; however, this

does not match

the 2001 RED.

 Post

- harvest

broadcast aircraft, airblast 2.0 WDG, EC 2.0 NA 1 NA NA 24 NS Permitted in California, Oregon and Washington.

### 32 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

Total 2.0 WDG, EC 4.0 NA 2 NA NA 24 NS Multiple types of applications may occur in within a year in California, Oregon and Washington such as a post

- harvest application and a dormant, delayed

dormant.

Excludes

nursery applications (See general “Fruits” listing)

PEAS

 Preplant Seed

treatment Seed Treatment 0. 30

0.0 00 625 lb/lb

seed

WP

0.28

0. 00 058 lb/lb

seed

EC NS NS NS NS NS NS NS There is a range of potential application rates depending

on the number of seeds per lb

and the number of seeds planted

per acre. Seeding

information provide by

BEAD. 2

### 33 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

PECANS

 dormant/ delayed

dormant

broadcast aircraft, airblast 2.0 EC, WDG 2.0 NA 1 NA 14

24 10 66222

- 19 and

66222

- 233

 foliar ;

broadcast airblast 4. 3 EC, WDG

6. 3 NA 3 NA 14 10 Some labels require a 28 d

PHI

aircraft 2.0

EC, WDG Updated to reflect spray drift mitigation.

 foliar;

orchard

floors

broadcast Ground boom,

chemigation 4. 3

EC, WDG 4. 3 NA 2 NA 14 10

Total 4.3 12. 6 NA 6 NA 14 24 10 Considers multiple type of applications ( e.g. , dormant, foliar broadcast,

and orchard floor) but

e xcluding

nursery For nursery applications (See general “Fruits” listing)

PEPPER  Foliar Ground

broadcast 1.0

WDG [ 8 ]

NS 8.0 [ 8]

NS 8 7 24 10 Permitted in

Florida FL040005; 1

crop cycle per

year. PINEAPPLE  Postplant Ground boom, 2.0 6 .0 6.0 3 NA 365 24 30 Permitted in HI090001

### 34 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

broadcast EC Hawaii SNL Expires: March 29,

2014.

Do not make applications beyond three

months after planting.

PLUM/

PRUNE  dormant/ delayed

dormant ; broadcast Aircraft,

airblast 2.0

EC, WDG 2.0 NA 1 NA NA

24/

4d 10

 foliar;

trunk spray/drenc

h handheld,

backpack, drench/dip, handgun, and low pressure

hand wand 2.5

3.0/100 gal

WDG 2.5 NA 1 NA NA 10

Total 2.5 4.5 NA 2 NA Excludes

nursery applications (See general “Fruits” listing)

POULTRY

LITTER
 When needed,

animal bedding/litter

treatment. Sprayer 0.07126 a.i./1000 sq ft

3.1

ME NS NA NS NA NA NS 53883

- 264,

84575

- 3

PUMPKIN
 Preplant Seed

treatment Seed treatment 0.3

0.0 00 58 lb /lb

seed [0.3]

NS [1]

NS [1]

NS 1 NS NS NS California

maximum single rate There is a range

of potential application

### 35 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

WP 0.0 00 625 lb

a.i. /lb. rates depending

on the number of seeds per lb

and the number of seeds planted

per acre. Seeding

information provide by

BEAD. 4

RADISH

 Foliar Broadcast ground 1.0

EC NS 1 NS 1 NS 24 NS permitted in Oregon OR090012 on

radish grown

for seed.

Label valid

until December 31, 2012. (per registrant SLN still valid)

 Preplant Soil incorporation ground 3.0

EC 12 .0 3 4 1 NS NS 10

 At plant/post

-

plant In furrow

drench/

treatment 3.0

EC

2.8

G [15.0]

NS 3 [5]

NS 1 30,

EC,

7,

G 24 10 Only one granular application permitted.

Total 3.0 [22.0]

NS 2 [9]

NS Only one preplant or at plant application is

assumed.

### 36 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

RIGHTS OF WAY, ROAD

MEDIANS When needed, soil

broadcast Granular or low

pressure wand 1.0

EC, G, Bait [2.0]

NS NA 2 NA NA NS 7 Apply when

needed

RUTABAGA

 Preplant Chemigation,

Groundboom 2.4

EC, WDG [4.8]

NS 2.4 [2]

NS 1 30 24 10

Aerial 2.0

EC, WDG 2.0 Updated to reflect spray drift mitigation.

 At plant/post

-

plant In furrow

drench/

treatment 2.4

EC, G WDG 4.8 2.4 [2]

NS 1 7 24 10 Disallowed

in California

and Arizona. Two c rop

c ycles per year

Total 2.4 [9.6]

NS 4.8 [4]

NS 2 24 10

SEWER

MANHOLE

COVERS AND

WALLS When needed Low pressure 0.31

lb/manhole

RTU NS NA NS NA NA NA NS 3 pints product/

manhole

SEED

ORCHARD

TREES  foliar ; broadcast Ground boom 1.0

EC 3.0 3 .0 NS NA 30 24 7 62719

- 575,

62719

- 615

 High volume

sprayer 2.5

0.01

a.i./tree

0.02 EC 2.5 NS [1]

NS NA 30 24 7 Cone worm

treatment (62719

- 575 and

62719

- 615)

Treatment of 1000 trees per

acre would

results in an single application rate

of 10 lb a.i./a.

### 37 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

DAS: 1000 is a bit high, typically for

orchards 312

trees per acre

 foliar; stump

treatment backpack,

drencher, low pressure hand wand, 0.3

EC 0.3 1 .0 NS NA 30 24 7 62719

- 575,

62719

- 615

Total 1.0 5.8 3 NS NA 30 24 7 The total

number of applications

assumed is

either three

foliar applications or

two foliar applications with one stump

treatment.
SORGHUM

GRAIN

 Seed

Treatment Seed treatment [0.0 009 ]

0.01

- 0.0024 lb ai/

100 lbs seed

EC 0.01 0.01 [1]

NS 1 NA NS NS 264

- 932

 Preplant Soil

Directed Ground

Spreader/T

Band 1.5

G 1.5 1.5 [1]

NS 1 60 24 10

 Foliar/Post

emergent Ground, Aerial,

Chemigation 1.0

EC, WDG 1.5 [1.5]

NS [1]

NS 3 30 24 10 PHI varies

across labels

Total 3.3 3 .01 3.01 [3] 3 30 24 10 One crop cycle

### 38 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

G

1.0 EC, WDG CBD per year.

SOYBEAN  foliar , post

- emergence soil broadcast broadcast

ground, aerial, chemigation 1.0

EC, WDG 3 .0 3.0 3 3 28 24 14 One crop c ycle

per year

.

 At plant/post

plant

treatment;
soil band ground boom 2.2

G

1.0 EC 3.0 3.0 1 (G), 3 (EC) 1 (G),

3 (EC) 28 24 10

Total 1.0 EC, WDG

2.2

G 3 .0 3.0 3 3 One crop cycle

per year.

STRAW

- BERRIES  Pre

- plant Aerial or ground/

broadcast 2.0

EC 2.0 NS 1 NS NA 24 10 No use in Mississippi 33658

- 26

 Foliar Aerial or ground/

b roadcast, foliar

spray 1.0

EC, WDG 2.0 NS 2 NS 21

24 10 Two applications (2 lb ai) for all products per cc.

 Post harvest Ground d irected

spray 1.0

EC, WDG 2.0 NS 2 NS 21 14

Total 2.0 4.0 3 One preplant application and

two foliar

and/or postharvest application

### 39 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

permitted per

year. SUNFLOWER  At plant

Aerial / ground 2.0

G 3 .0 3.0 [1]

NS 1 42

24 10 Per registrant 1

cc per year

 Preplant 2.0 EC, WDG 3 .0 3.0 [1]

NS 1 42 10 2 inches min incorporation

 Post

emergent or
foliar 1.5 EC, WDG 3 .0 3.0 [2]

NS 2 42 10

Total 2.0 5 .0 5.0 3 3 Assumed either an at plant or preplant application

followed with

two foliar applications.

One c rop c ycle

per year

SWEET

POTATO  Preplant, soil

broadcast Aircraft, ground

boom 2.1

G, EC, WDG

2.1 NS 1 1 125 24 LA090002, MS080007,

NC090001 permits 60

PHI Aircraft 2.0

G, EC, WDG Updated to reflect spray drift mitigation.

TOBACCO  Preplant Aircraft, ground

boom 2.0

EC, G, WDG 2.0 NS 1 1 7 24 NA

TRITICALE  Storage

Commercial Slurry Seed

Treatment Seed treatment 0.003

0.0024 lb ai/

100 lbs seed

EC [0.003]

N S [1]

NS [1]

NS [1]

NS NA [10

]

NS [10]

NS 264

- 932

Seeding

information provide by

BEAD. 4

### 40 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

One crop cycle

per year.

TURNIP  Preplant soil incorporation/ ground boom, handgun 2.3

G, WDG [4.6]

NS 2.3 [2]

NS 1 30 24 10 Minimum incorporation:

2 inches.

 Postplant Soil incorporation/ ground boom, handgun 2.3

G, WDGP [4.6]

NS 2.3 [2]

NS 1 30 24 10 Minimum incorporation:

2 inches.

Total 2.3 4.6 2.3 2 1 30 24 10 Assumed either a preplant or postplant application.

Two c rop

c ycles per year UTILITIES

For use in and

around

telecommunicatio ns, power, utilities

and railroad
systems equipment: Buried cables,

cable television pedestals, cables, pad

- mounted electric power transformers, telephone cables, When needed,

broadcast Product

container 190.5

G

0.44 lba.i./100 sq ft (see comments) NS NS NS NS NS NS NS Applications permitted as needed. Reg.

Nos. 13283

- 14,

13283

- 17

Broadcast product onto the ground covering the

area of the pad location, plus a

two foot perimeter

around the

outside of the

### 41 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

underground vaults,

telecommunicatio ns equipment,

power and utilities equipment pad location.

WALNUTS

 dormant/ delayed

dormant ; broadcast Aircraft,

airblast 2.0

EC, WDG 2.0 NA 1 NA 14

24 10 62719

- 301 (12 lb a.i./A)

 foliar ;

broadcast aircraft,

airblast, chemigation 2.0

EC, WDG 4.0 NA 2 NA 14 10 Some labels do not specify

retreatment
interval.

 foliar;

orchard

floors

broadcast Ground boom,

chemigation 4.0

EC, WDG 4.0 NA 1 NA 14 10

Total 4.0 10.0 4 Excluding

nursery applications;

includes dormant, foliar broadcast, and

orchard floor. For nursery applications (See general “Fruits” listing)

WIDE AREA/

GENERAL   when needed,

Broadcast Ground sprayer 0.5084 lb ai/100 gal [1.02]

NS NA 2 NA NA NS NS 66222

- 19

### 42 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

OUTDOOR

TREATMENT

For ants and other misc. pests. EC

when needed,

Drench Drench 1 NS NA NS NA NA NS 228

- 624
[1]

8.2 lb a.i/100 gal EC NS NA NS NA NA NS 228

- 625

Total [1] NS NA NS NA NA

WHEAT

 Slurry Seed

Treatment Seed treatment 0.003

0.0024 lb ai/

100 lbs seed

EC [0.006]

NS 1 [2]

NS 1 NA NA NA

Only for use in AZ, CA, CO, ID, KS, MN, MO,
NE, NM,
NV, ND, OK, OR, SD, TX, UT,

WA and WY Seeding

information provide by

BEAD. 4

 Foliar, soil

treatment Ground,

broadcast 0.5

EC [8.0]

NS 4.0 [2]

NS 1 14/

28

24 14 PHI: 14 forage or hay, 28 grain

or straw

 Post

-

emergence foliar Ground, Aerial,

Chemigation 1.0

EC [4.0]

NS 2.0 [4]

NS 2 14/

28 NS Label states 1.0

lb ai/A for

cereal leaf

beetles and then

state max rate
0.5 lb ai/A in restriction).

Some labels

restrict n o more than 2 applications per crop/season

PHI 14 forage or hay, 28 grain

or straw

Total [1]

4.0 [12.006

] [6.003]

5.0 [8]

NS [4]

2 MO otherwise 2.0 plus seed

### 43 Crop/Site

Residential Agricultural Forestry Timing; Application Type Method/

Equipment Maximum

Single Application Rate by

Formulation 1
(lb a.i./A) Maximum

Application Rate Maximum

Application

Number

PHI (days) 3 REI (hours) 3 MRI (days) 3 Geographic

Restrictions Comments
Per

Year

lb

a.i./A Per

CC 2

lb a.i./A Per

Year Per

CC 2

EC treatment
WOOD

PROTECTION

TREATMENT

TO

BUILDINGS/

PRODUCTS

OUTDOOR When needed,

Wood

surface

treatment Low pressure

handwand,

backback

sprayer, paintbrush 16.65

lb/10,000 sq ft 0.17 lb a.i./gal

EC NS NA NS NA NS NS NS

0.08 lb ai/gal EC, RTU EC,

ME NS NA NS NA NS NS NS Apply 1 gal per 100 sq ft of

wood

1. EC

- emulsifiable concentrate; WDG

– water dispersible granular in water soluble packet; WP

– wettable power in water soluble packet; B

– bait (granular), G

– granular; ME

– microencapsulated; RTU

– ready to use.

2. Reported as per crop cycle or per season

3. PHI

– Preharvest interval; REI

– reentry interval; MRI

– Minimum retreatment interval

4. Becker, J.; Ratnayake, S. Acres Planted per Day and Seeding Rates of Crops Grown in the United States, U.S. EPA OPP/BEAD, 2011; example calculations provided below:

Beans: 0.0 00 58 lb a.i./lb seed / 960 seeds/lb seed x 418,176 seeds/A [pgs. 19, 81 (beans, succulent)]

Corn: 0.0 00 625 lb a.i./lb seed / 1,800 seeds/lb seed x 59, 739 seeds/A [pgs. 24, 81 (corn, sweet)]

Cotton: 0. 00 116 lb a.i./lb seed / 4,500 seeds/lb seed x 85,00 seeds/A [pgs. 13, 81]

Cucumber: 0. 00 05 8 lb a.i./lb seed / 12,000 seeds/lb seed x 80,418 seeds/A [pgs. 25, 81]

Peas: 0.0 00 625 lb a.i./lb seed / 1,361 seeds/lb seed x 653,400 seeds/A [pgs. 34, 82] Pumpkin : 0.0 00 58 lb a.i./lb seed / 1,600 seeds/lb seed x 7,260 seeds/A [pgs. 37, 82] Sorghum: 0.001 lb a.i./lb seed / 11 ,000 seeds/lb seed x 100,000 seeds/A [pgs. 16, 39]

Tri ticale: 0.0 03 lb a.i./100 lb seed / 109 lb seed/A [pg.16]

Wheat: 0.003 lb a.i./100 lb seed /116 lb seed/A [pg. 16] [ ] indicate assumptions that are made when the information is not specified but can be inferred