# Presentation: 547343

## Cumulative Risk Assessment: 

*Cumulative Risk Assessment: *
- Drinking Water Exposure Methodology for the Organophosphorus Pesticides

- Technical Briefing

- U.S. EPA
- Office of Pesticide Programs
- October 3, 2001

## Lois Rossi, Director
Special Review and Reregistration Division
Elizabeth Leovey, Acting Director
Environmental Fate & Effects Division

Denise Keehner, Director
Biological & Economic Analysis Division

- Special Review and Reregistration Division
- Elizabeth Leovey, Acting Director
- Environmental Fate & Effects Division
- Denise Keehner, Director
- Biological & Economic Analysis Division

*Welcome and Introduction*

## Goals of Today’s Meeting

**Goals of Today’s Meeting**

**Lois Rossi**
- Director
- Special Review & Reregistration Division

## Goals & Purpose of Briefing

- Part of process the Agency has developed in conjunction with CARAT Workgroup on OP Cumulative Process
- Update stakeholders
- Provide explanations of methods as early as possible

## Goal

- Stakeholders understand methods & data so that they can provide effective input
- Find ways of enhancing transparency and ease of stakeholder participation in the drinking water aspect of the assessment

## Cumulative Assessment Represents New “Paradigm”

- Clearly not just a compilation of individual chemical risks
- Different way of looking at risk
- Different questions
- Different methods
- Different risk management considerations

## Developing Common Understanding of New Paradigm

- Natural to want to know the     “bottom-line”
- What are the risk numbers?
- What will be the regulatory outcome?
- Will these methods be used for other groups?

## Developing Common Understanding of New Paradigm

- Why “bottom-line” must wait
- Numbers are not currently available and would not be fully QA/QCed until preliminary risk assessment is completed
- Need to have a common understanding of the methods/paradigm before there can be meaningful dialog on regulatory outcome
- Application to other groups will not be known immediately
- Depends on conclusions regarding methodology
- Depends on specific characteristics of the other groups

## Understanding New Methods

- A big piece is analyzing variability
- What are the major factors contributing to risk
- i.e. what matters & what does not
- Analyze information sources
- Refine risks where necessary
- Understanding uncertainty
- Agency committed to doing this

## In Summary

- Focus on methods
- Prepare for release of preliminary assessment
- Stakeholders prepared to review preliminary assessment
- Understand what is important in preliminary assessment
- Contribute to the Agency’s ability to conduct appropriate refinements
- Prepare proper foundation for analyzing risk mitigation, if necessary

## Agency & Stakeholder Cooperation

- Due to development of many new methods for cumulative, the Agency is providing briefings on these methods & the status of the assessment _before_ the preliminary risk assessment is issued
- Stakeholders must recognize certain elements (both small & potentially large) may change
- Therefore, we all must work together cooperatively; to use the information constructively; and for the purpose of providing useful input

## Steps for Conducting a Cumulative Risk Assessment

- Identify Common Mechanism Group

- Identify Potential Exposures

- Determine Cumulative Assessment Group

- Conduct Final Cumulative Risk Assessment

- Conduct Characterization of Cumulative Risk

- Characterize + Select Common
-  Mechanism Endpoint(s)

- Determine Absolute & Relative Toxic Potencies of Chemicals & Point of Departure for Index Chemical

- Develop Detailed Exposure Scenarios
- for all Routes & Durations

- Establish Exposure Input Parameters

## Goals of Today’s Meeting

**Goals of Today’s Meeting**

**Denise Keehner**
- Director
- Biological & Economic Analysis Division

## Why Use & Usage Information Is So Important

- Key element of preliminary cumulative drinking water assessment methodology is estimating OP concentrations over time in specific watersheds in about a dozen different regions of the U.S.
- In order to estimate concentrations in these locations, we will be predicting pesticide movement from application on the land in a watershed to a drinking water source in the watershed

## Why Use & Usage Information Is So Important

- Although there are many variables which influence pesticide movement to surface water including:
- Pesticide use intensity
- Amount of area around surface water source that is cropped and treated
- Application method
- Weather patterns in relation to timing of pesticide use
- Pesticide properties such as solubility and persistence
- Soil properties such as capacity of a particular soil to hold more or less water...

## Why Use & Usage Information Is So Important

- Scientists have demonstrated that the vast majority of the variability in pesticide concentrations in surface water systems can be attributed to:
- Pesticide use intensity (application rate and frequency)
- Percent of the surrounding land area that is cropped and treated
- Soil properties such as capacity of a soil to hold more or less water
- This means that OP use and usage data on a watershed basis (including the timing of different OP applications in each watershed) is among the most significant inputs to the cumulative drinking water assessment

## OPP’s Goal for Use and Usage Information

- Provide as accurate/real world use and usage data as possible for each of the selected watersheds in each of the regions for each of the OP/crop combinations that existed in that watershed, we are:
- Not forecasting, but basing on current use
- Using typical (predominant) not maximum rates/frequencies
- Using information on timing of applications in specific areas
- Important in determining co-occurrence in single drinking water sources

## OPP’s Goal for Use and Usage Information

- OPP’s goal is to deliver the above using the best available information for the preliminary cumulative risk assessment in a way that is transparent:
- Using national survey data from NASS and others
- Using available use/usage data from States
- Using crop profiles from USDA
- Using regional and local commodity experts

## OPP’s Goal for Use and Usage Information

- Dr. Leo LaSota from BEAD will describe later today in more specific terms the types of usage information needed for the preliminary assessment and what the sources and approaches have been to collecting this information

## OPP’s Goal for Use and Usage Information

- One final comment – it is important to recognize that after the completion of the preliminary cumulative risk assessment, the Program may find that there is a need to “drill” deeper and understand with even more precision use and usage
- May need to better understand timing at smaller scale than areas initially evaluated or at additional areas
- Not clear yet whether this level of refinement will be necessary
- Enhancements in the quality of use and usage information important element of public participation in the preliminary cumulative risk assessment

## Drinking Water Methods:

**Drinking Water Methods:**
**Progress to date**

**Dr. Elizabeth Leovey**
- Acting Director
- Environmental Fate & Effects Division

## CUMULATIVE OP ASSESSMENT

- Drinking Water Methods Development: Progress to Date
- Historical perspective of drinking water exposure assessment from FQPA passage to present
- Origins of the methodology being presented today
- Evolving process with substantial guidance from the FIFRA Scientific Advisory Panel and the public

## Goals of OPP’s Drinking Water Assessments

- Understand occurrence, human health risks associated with occurrence, and factors influencing occurrence of approximately 400 food-use pesticides in drinking water
- Who is exposed to what, where, for how long, and what are the risks?
- What can be done to mitigate/reduce risks?

## Goals of OPP’s Drinking Water Assessments

- Develop methods, approaches and tools to appropriately factor occurrence of pesticides in drinking water into FQPA human health risk assessments
- Conduct objective, timely, scientifically sound pesticide-specific assessments of occurrence, using cost-effective, scientifically sound process

## Drinking Water Exposure: The Beginning

**1996 FQPA**
- All anticipated dietary exposures - Drinking Water included in dietary exposure assessments
- Models to estimate exposure to aquatic organisms were available
- GENEEC - Screening Tier
- PRZM/EXAMS - Higher Tier
- Modeled a Farm Pond - 10 hectare field following into a 1 hectare pond x 2 meters deep
- Agency proceeded to develop methods, data and assessment methodology that actually estimated human pesticide exposure from drinking water

## 1997

- Advice obtained from International Life Sciences Institute (ILSI)
- Charge: Identify improvements to existing screening methods which could be implemented in the short-term
- Reports:
- 1998 - Assessment of Methods to Estimate Pesticides in Drinking Water Sources

## 1997

- Dec. 1997 - SAP “Estimating Drinking Water Exposure as a Component of the Dietary Risk Assessment”
- SCI-GROW, GENEEC & PRZM/EXAMS reviewed and SAP recommended implementation
- SAP recommended that the Agency devote its resources to surface water, define higher assessment tiers and develop techniques for estimating concentration distributions for probabilistic risk assessments
- Assessment approach was defined that used both modeling and monitoring data

## 1997

- Science Policy Papers
- Estimating the Drinking Water Component of a Dietary Risk Assessment (draft, 1999)
- In response to comments, enhanced use of monitoring data and cooperative efforts with USGS were increased to develop additional monitoring data
- Pilot Reservoir Study - Two year monitoring of 9 to 12 reservoirs, pre and post treatment
- Detailed procedures described in Standard Operating Procedure (SOP) for Incorporating Screening-Level Estimates of Drinking Water Exposure into Aggregate Risk Assessments (draft, 2000)

## 1998

- ILSI Working Group
- Charge: Develop guidance on probability distributions of pesticide concentrations in drinking water and incorporation of monitoring and monitoring data into aggregate exposure analysis for the long term
- 1999 - A Framework for Estimating Pesticide Concentrations in Drinking Water for Aggregate Exposure Assessments

## 1998

- July 1998 - SAP “Proposed Methods for Basin-Scale Estimation of Pesticide Concentrations in Flowing Water and Reservoirs for Tolerance Reassessment”
- SAP recommended that OPP move forward on Index Reservoir and account for amount of cropping in the watershed
- Shipman City, Illinois reservoir
- Recommended that a number of watershed models proposed be evaluated (currently in progress)

## 1999

- May 1999 - SAP “Proposed Methods For Determining Watershed-Derived Percent Crop Areas and Considerations for Applying Crop Area Adjustment to Surface Water Screening Models”
- Percent Crop Areas - Corn (0.46), Soybeans (0.41), Wheat (0.56), and Cotton (0.2)
- SAP recommended regional modeling
- Science Policy Paper - Drinking Water Screening Level Assessment
- Part A: Guidance for Use of the Index Reservoir in Drinking Water Exposure Assessments
- Part B: Applying a Percent Crop Area Adjustment to Tier 2 Surface Water Model Estimates for Pesticide Drinking Water Exposure Assessments (draft, 2000)

## 2000

- Sept. 2000 SAP - Literature review on effect of water treatment on pesticides
- SAP recommended that water treatment should not be considered a viable pesticide removal process in drinking water based on the lack of data on water treatment effects
- SAP recommended that drinking water assessments should be conducted on raw water rather than treated water unless data was available

## 2000

- March 2000 - SAP “Development and Use of Distributions of Pesticide Concentrations in Drinking Water for FQPA Exposure Assessments”
- SAP commented that the Larson-Gilliom   (WARP model) showed promise
- June 2000 - SAP National Drinking Water Survey Design for Assessing Chronic Exposure
- Shift focus to developing regression models so that continual monitoring programs would not be needed

## 2000

- Sept. 2000 - SAP “Progress Report on Estimating Pesticide Concentrations in Drinking Water and Assessing Water Treatment Effects on Pesticide Removal and Transformation”
- Dec. 2000- SAP “A Case Study of the Cumulative Risk of 24 Organophosphate Pesticides”
- Regression model WARP was used in the case study
- SAP concluded that additional monitoring data was needed to complete model

## Present

- MODELS
- Index Reservoir/Percent Crop Area
- SCI-GROW
- Temporal
- Spatial
- Concentration Distributions
- MONITORING DATA:
- Compare with modeling results, if adequate, use in assessments

## OPP Cumulative Drinking Water Team

- Composed of staff
- Special Review and Reregistration Division
- Health Effects Division
- Environmental Fate and Effects Division
- Biological and Economic Analysis Division
- OPP Immediate Office
- Developed the methodology being presented today over several months

## Today’s Presenters

- Lois Rossi (SRRD)
- Elizabeth Leovey (EFED)
- Denise Keehner (BEAD)
- Laura Parsons (SRRD)
- David Miller (HED)
- Leo LaSota (BEAD)
- Steve Nako (HED)
- Nelson Thurman (EFED)

## Intro to the Cumulative Exposure Assessment

**Intro to the Cumulative Exposure Assessment**

**Laura Parsons**
- SRRD

## Roadmap

- Development of drinking water methods
**Introduction & overview**
- Probabilistic methods a necessity for cumulative
- Summary of proposed methods
- Use information:
- Accounting for valid co-occurrence
- Use information:
- Sites, crops, use patterns
- Summary and next steps

## Cumulative Drinking Water Assessment Team

- EFED
- Kevin Costello
- Ian Kennedy
- Stephanie Irene
- Nelson Thurman
- HED
- Steve Nako
- David Miller
- David Hrdy
- Bernard Schneider
- Yuen-Shaung Ng

- BEAD
- Leo Lasota
- Neil Anderson
- Art Grube
- David Widawsky
- SRRD
- Bentley Gregg
- Laura Parsons

## Introduction and Overview

- Review today’s agenda
- Emphasize major points to keep in mind

## Introduction and Overview

- This briefing will discuss the methods and input data EPA is using in the OP cumulative assessment
- All input files will be made available when the preliminary assessment is complete

## Introduction and Overview

- The cumulative water assessment is very different than the water assessments done for individual OP compounds
- This results primarily from differences in the questions the assessments address

## Introduction and Overview

- The **individual chemical drinking water assessment** begins by estimating a reasonable high end level of residues that might occur
- For single representative crops
- Generally on single representative areas

## Introduction and Overview

- The **cumulative assessment** focuses on the likelihood a person will be concurrently exposed to multiple pesticides from food, water, and residential use

## Introduction and Overview

- The goal of the exposure assessment for water is to estimate daily concentrations of pesticides in localized drinking water sources for use in a probablistic assessment
- Daily concentrations are the “building blocks” for estimation of exposure for any time period
- Start with a daily concentration to combine with daily food consumption (and ultimately daily residential exposure)
- These daily exposures can then be combined to build a longer time of exposure whether it’s a week, month or longer

## Introduction and Overview

- History and development in drinking water exposure methodology since passage of FQPA
- We’ll provide a framework for how drinking water fits into the overall cumulative assessment

## Introduction and Overview

- Proposed method for drinking water estimates for surface and ground water illustrated in detail

## Introduction and Overview

- This is a regional water assessment rather than a national assessment as was used for the individual OPs.  Regions based on USDA’s Economic Research Service map
- Regional approach allows realistic combining of water and residential exposures which have a local component

## Introduction and Overview

- Analysis uses both modeling estimates and monitoring data

## Introduction and Overview

- Monitoring data shows that multiple pesticides may be found in a single water sample
- Modeling will account for this co-occurrence:
- Crop combinations which can occur in the same watershed
- Pesticides used concurrently are considered together

## Introduction and Overview

- Actions taken on individual OP’s will be reflected in the cumulative assessment
- For example, residential uses of chlorpyrifos and diazinon are not considered in this assessment

## Introduction and Overview

- A regional Percent Cropped Area will be estimated from National Land Cover Data and Agricultural Census Data
- Additionally, an “Acre Treatment Factor” will be used to further modify the estimates to account for the scale of the watershed and the amount of each pesticide used there based on available use statistics

## Introduction and Overview

- Use information from USDA databases, state surveys, and grower groups used for input parameters to the modeling estimates
- Application rates & application timing are from “typical” (i.e. actual reported use)

## Introduction and Overview

- Agricultural statistics will be used to estimate relative amounts of compounds which would be applied for the same crop and timeframe
- Ensures that pesticides used for the same purpose (competitors) will not be assumed to be used at the same time

## Water and the Risk Assessment Process

**Water and the Risk Assessment Process**

**David Miller**
- Health Effects Division

## Roadmap

- Development of drinking water methods
- Introduction & overview
**Probabilistic methods a necessity for cumulative**
- Summary of proposed methods
- Use information:
- Accounting for valid co-occurrence
- Use information:
- Sites, crops, use patterns
- Summary and next steps

## Introduction

- Both Food and Water exposure estimates used in a probabilistic assessment for cumulative risk
- This presentation does not address residential exposures
- Next slides detail:
- How food risk is estimated probabilistically
- How water risk is currently estimated
- How water exposure would need to be estimated to be combined in a probabilistic estimate with food
- Subsequent presentations will cover information on how water concentrations are estimated

## Outline 

- Risk Equation
- Using DEEMTM software for Assessments for Food (alone)
- FQPA requirement for Aggregation/Cumulation
- Interim Methodology and DWLOCs
- How to calculate
- Proposed Aggregation/Cumulation Methodology using DEEM/Calendex
- Importance of Calendar-based Assessment
- Illustrative step-by-step example of Aggregate/Cumulative Assessment for Food and Drinking Water

## Risk Equation

- Risk is the probability that a substance will produce harm under specified conditions
- Risk = f(Exposure, Hazard)
- Hazard part derived from toxicological studies
- Exposure part derived from residues and consumption

## Exposure From Food

- We use DEEMTM (Dietary Exposure Evaluation Model) software to estimate exposures from food
- Exposure =  consumption x residue
- DEEM produces an estimate of the *distribution* of exposures through food
- Uses probabilistic (Monte-Carlo) techniques

## DEEM Software

- Uses data on food consumption and data on pesticide concentration to estimate exposures from food
- Food Consumption
- USDA’s (CSFII) Continuing Survey of Food Intakes by Individuals
- Survey reports daily consumption of food for 30,000+  person-days of consumption
- 1989-91, 1994-96, and 1994-96/1998 data available
- Pesticide Residues
- Market Basket Data
- USDA PDP data
- FDA Monitoring data
- Crop Field Trial data

## Aggregate and Cumulative Risk

- FQPA requires OPP to *aggregate* exposure and *cumulate* risk
- _Aggregation_ = considering exposures from *same* chemical across pathways (e.g., residential, food, water)
- _Cumulation_ = considering risks from *different* chemicals with a common mechanism of action

## Aggregation (for individual chemicals)

- OPP is currently using OPP Interim Methodology to perform this aggregation
- Interim methodology uses DWLOC (Drinking Water Level of Comparison) to evaluate acceptability of exposure
- Interim methodology
- Evaluates whether aggregate exposure is acceptable
- Does this by using DWLOC’s (Drinking Water Levels of Comparison)

## What are DWLOC values?(Drinking Water Levels of Comparison)

- A DWLOC value is a concentration limit for a pesticide in drinking water which, when combined with exposures from food, would result in aggregate exposure equal to the PAD (“safe” exposure)
- based on how much additional exposure through water would be acceptable once exposures in food have been estimated

## Why Use DWLOC values?

- Permit a determination of whether aggregate exposures are “obviously acceptable” or *potentially* “unacceptable”
- Considered a screening process

## Calculating DWLOCs

- Room
- Available
- For Water

- FOOD

- FULL CUP
- (Allowable
- Exposure =
- 10 mg/kg/dy

**?**

## Calculating DWLOCs

- FULL CUP

-  10 mg/kg/day – 6 mg/kg/day =
-  **4 mg/kg/day**
-  4 mg/kg/day x 70 kg bwt. ÷ 2L/day = **140 ppm (mg/L)**
-  140 ppm = **DWLOC for acute effects in adult males**

- FOOD

## Issues With Use of DWLOC Approach

- Not a probabilistic approach
- Doesn’t simultaneously evaluate food and water exposures
- Back-calculates an “allowable” water concentration by assuming a simultaneous high-end exposure through food
- Residential exposures not considered

## DEEM/Calendex Cumulative Assessment

- DEEMTM and CalendexTM can be used to combine water distributions with food distributions probabilistically
- CalendexTM builds upon DEEM (food) exposure calculations by *simultaneously* evaluating pesticide exposure from food, water (and residential non-occupational sources)

## DEEM/Calendex Cumulative Assessment

- DEEM/Calendex provides a probabilistic assessment
- DEEMTM /CalendexTM incorporates concept of a Calendar to evaluate aggregate exposures
- Time-based approach
- Calendar-based approach looks at each individual day of the year
- Calendar-based approach allows appropriate “temporal matching” of exposures through food and  drinking water (residential pathways, too)
- Temporal aspect of exposure through water (and residential uses) important for OP’s due to expected seasonal pulses and seasonal use-patterns

## DEEM/Calendex Cumulative Assessment

- What would happen if we didn’t use calendar-based approach?
- For example:
- Spring run-off concentration in drinking water could be (incorrectly) combined with fall dermal exposure through lawn-use
- Spring run-off concentration in drinking water on one day could be (incorrectly) considered consecutively with a day of winter concentration

## Key Concepts in Cumulative Assessment: Appropriate Matching and Combining 

- Objective:  to appropriately match and subsequently combine estimates of pesticide residues in food with estimates of pesticide residues in water

## Key Concepts in Cumulative Assessment: Appropriate Matching and Combining

- Matching and combining must appropriately consider temporal and spatial factors associated with exposure
- the time-sequence of pesticide concentrations in water is important and must be preserved
- Therefore, using a daily time series of predicted drinking water concentrations
- the spatial component of pesticides in water is important and must be preserved
- Therefore, performing assessments on a regional basis

## Key Concepts in Cumulative Assessment: Appropriate Matching and Combining

- In summary, must track potentially exposed persons on a daily basis in a way that preserves all appropriate linkages
- For example:
- Temporal
- Spatial
- Demographic

## Key Concepts in Cumulative Assessment: Appropriate Matching and Combining

- To preserve appropriate linkages requires:
- Model to link and calculate daily exposures
- Distribution of exposures that reflect
- Daily estimates
- Specific regions of the country

## Quantitative Exposure Assessment: Calendex/DEEM & Region-specific Analysis

- For each of the multiple cumulative assessment regions:
- Maintain temporal & spatial characteristics
- Use DEEMTM software to estimate exposure from food
- Use Calendex software to aggregate/cumulate exposure from food and drinking water (and residential exposures)

## Illustrative Example of Calendex Analysis

- Next several slides show conceptual example of an aggregate/cumulative assessment of one day of exposure in which exposures through food and drinking water are combined
- 1-day exposure is presented as an example
- Analysis serves as “building block” for any number of days analysis (“rolling” or “sliding” average)
- Residential exposures in this example are _not_ considered

## Illustrative Example of Calendex Analysis

- Hypothetical Consumption Profile for CSFII Individual #1:
- 62 kg person
- Consumed:		260 g food #1
- 				320 g food #2
- 				250 g food #3
- 				1560 g water (=1560 mL)
- Period of Interest: January 1 through December 31
- Specific to Region of Interest

## Illustrative Example of Calendex Analysis

- STEP 1:  Calculate Exposure from Food for Individual #1 on Day #1
- Food Exposure(from DEEM):   =   2.89x 10**-5** mg/kg bw/day
- STEP 2:  Select Water Consumption for Individual #1
- E.g., 1560 mL
- STEP 3:  Randomly select year from multiple years of daily water values
- STEP 4 : Assign the Water Concentration from January 1 from that year to Individual #1

## January 1

## Illustrative Example of Calendex Analysis

- STEP 5:  Calculate Exposure from Water by pairing water consumption value with selected water concentration value for January 1
- 		Water:  (1560 mL x 0.00053 mg/L)/62 kg = **1.33 x 10****-5**** mg/kg bw/day**
- STEP 6:  Aggregate with Food Exposure for January 1
- 1.33 x 10-5 + 2.89 x 10-5 = **4.22 x 10****-5**** mg/kg bw/day**
- STEP 7 :  Repeat  Steps 1-6 many additional times for this individual, randomly selecting a year each time and selecting January 1 concentration associated with that year

## Illustrative Example of Calendex Analysis

- STEP 8:  Continue steps 1-7 with Individual #2 through Individual # ~15,000
- Result is a collection (or distribution) of aggregate exposures for January 1 for the relevant region
- STEP 9: Repeat steps 1-8 for January 2
- Result is a collection (or distribution) of aggregate exposures for January 2 for the relevant region

## Illustrative Example of Calendex Analysis

- STEP 10: Repeat steps 1-9 for January 3 through December 31
- Result is a collection (or distribution) of aggregate exposures (food and water combined) for each day of the year for the relevant region
- These exposures can be plotted as a “time-line” of daily exposures for any given percentile in the distribution

## Illustrative Example of Calendex Analysis

- Exposure in mg/kg BW/day at a given percentile

## Illustrative Example of Calendex Analysis

- Example analysis illustrated a one-day exposure
- Probabilistic consideration of food and water
- Internally consistent
- Can be extended to multiple day exposures
- For example, seven-day (sequential) average
- Sequential days are in the same year

## Summary

- Food and Water (and residential) will be considered probabilistically in the cumulative assessment
- Temporal and Spatial Characteristics will be preserved and maintained to produce internally consistent assessments
- Result of Assessment will be a “time-trace” of exposures at any selected percentile
- Total Exposure and its food, water (and residential) components
- Single-day assessments will serve as “building block”
- Nelson will describe how we deal with the developing a set of daily water concentrations on a regional basis

## Proposed Methods for Estimating Drinking Water Concentrations

**Proposed Methods for Estimating Drinking Water Concentrations**

**Nelson Thurman**
- Environmental Fate & Effects Division

## Roadmap

- Development of drinking water methods
- Introduction & overview
- Probabilistic methods a necessity for cumulative
**Summary of proposed methods**
- Use information:
- Accounting for valid co-occurrence
- Use information:
- Sites, crops, use patterns
- Summary and next steps

## Cumulative Exposure

**Food**

**Water**

**Residential**
**uses**

- Risk = f(Exposure, Hazard)
- Exposure = Consumption X Residues

## Contrasting Water and Food

**Time**
- Pesticide concentrations in water vary daily, seasonally, yearly
- Food residue levels are more constant
**Location**
- Drinking water is locally derived and influenced
- food is distributed nationally
**Consumption**
- Drink water every day
- Generally from the same source

## How Do We Get There?

- Account for variations in place
- Usage, crops, site, weather, vulnerability differences
- Account for variations in time
- Daily fluctuations
- Seasonal, yearly fluctuations
- Co-occurrence of multiple chemicals
- Only as they occur together in place and time
- Provide distribution of daily concentrations for probabilistic exposure assessment

## Start With Water Monitoring

- U.S. Geological Survey
- National Ambient Water Quality Assessment (NAWQA)
- National Stream Quality Assessment Network (NASQAN)
- USGS-EPA Reservoir monitoring study
- State monitoring programs
- U.S. EPA monitoring databases

## ... Which Tells Us That...

- OPs are found in drinking water sources
- Surface water sources generally more vulnerable
- Agricultural and residential contributions
- Co-occurrence is likely
- Multiple OPs detected together
- There are potentially vulnerable areas
- Usage, vulnerability to runoff

## Meeting the Cumulative Needs

- Variations in place
- Covers a number of sites, but not all high OP use areas
- Variations in time
- Sampling not frequent enough for daily fluctuations
- Limited number of years (generally 3 or less)
- Consider multiple chemicals (co-occurrence)
- Not all OPs are included in monitoring
- Few or no OP degradates of toxic concern are included
- Does not reflect most recent regulatory actions

## How Will We Use Monitoring in the Cumulative Assessment?

- Planning and designing cumulative assessment
- Identifying vulnerable surface water sources
- Providing major source of data for ground water assessments
- Evaluating modeling estimates and calibration

## Additional Tools Were Needed for Cumulative Assessment

- In order to generate a daily distribution for combination with dietary and residential exposure, modeling is needed in addition to monitoring data
- The Agency has developed and adapted tools and information to provide a more realistic assessment of cumulative drinking water exposure

## What About Regression Models?

- Regression modeling tested in Cumulative OP Case Study
- Water contribution small relative to other sources
- Not all OPs included (only 2)
- Not highest OP use area (Mid-Atlantic)
- Included residential uses now cancelled
- Only as strong as supporting monitoring
- SAP: promising approach but needs further development

## Approach for Surface Water

*Approach for Surface Water*

- Modeling index reservoir with percent cropped area (IR/CAF) best currently-available tool
- Daily distributions
- Multiple years
- Multiple sites, crops
- Multiple chemicals
- Ongoing risk                                                            mitigation
- Real world use patterns
- Make use of extensive data                                                  on individual pesticide                                                  properties

## The Reason We Do This Is...

- What happens when we apply a pesticide to a field?
- How much pesticide is used?
- Where is the pesticide used and where are the drinking water sources?
- When is the pesticide used?
- What happens after application?

## This Is NOT a Screening Assessment

**Time:**
- Distribution of daily residues over multiple years rather than a point estimate
**Location:**
- Multiple sites instead of one high-exposure site
- Regional variations in crop and site factors
**OP Occurrence:**
- Typical rates, frequency rather than maximum label rates
- Multiple OPs used on each crop, multiple crops
- Co-occurrence only when it actually happens

## Refined Water Assessment

| Individual Chemical Screen | Cumulative OP Assessment |
| --- | --- |
| Single value:  e.g. 95th percentile concentration | Distribution of all daily concentrations |
| Comparison of single value to DWLOC value | Probabilistic assessment of water, food, residential exposures |

## Daily Distributions

## Daily Distributions

## Refined Water Assessment

| Individual Chemical Screen | Cumulative OP Assessment |
| --- | --- |
| National: Single vulnerable site represents entire US | Regional: multiple sites, regional differences in vulnerability |
| National percent crop area (PCA), assumes uniform crop intensity | Regional PCA: reflects regional variations in crop intensity |

## Drinking Water Varies Regionally

- Drinking water varies on a local scale
- Drinking water assessments for individual chemicals generally begin at a national scale
- Some refined assessments for individual OPs have gone to a regional scale
- Cumulative drinking water assessment will begin on a regional scale

## Addressing Variations in Location

- We looked for ways to account for similarities and differences in:
- Crops and agronomic practices
- Geographic and climatic factors that affect crops and pesticide use
- Regional factors that impact pesticide transport to water (weather, hydrology, soil, cropping area)
- Sources of drinking water

## Regional Framework

- Source: USDA ERS

## Using a Regional Framework

- The cumulative assessment _starts_ on the regional scale
- We focused our assessments on specific locations within the region
- If drinking water is a significant contributor in any region, we will be looking at variations within the region

## Factors in Building the Regional Cumulative Assessments

- OP usage
- What crops?
- What OPs and how much?
- Sources of drinking water
- Vulnerability of drinking water sources
- Runoff for surface water
- Leaching, depth for ground water

## Building the Cumulative Assessment

- Identify high OP usage areas within each region

## Building the Cumulative Assessment

- NW Fruitful Rim: southeast ID, eastern WA, western OR

## Building the Cumulative Assessment

- NW Fruitful Rim:
- Approximately 3-4 million lb of OPs used
- apple/orchards (~45%), potatoes (~35%) major uses
- wheat, barley, mint, alfalfa, sugar beets, vegetables
- In the high-use areas:
- Southeast ID (~200-500K lb; >90% potatoes, sugar beets)
- Eastern WA (~600K lb; 90% orchards)
- Willamette Valley, OR (~160K lb; orchards, vegetables, wheat, barley)

## Building the Cumulative Assessment

- Where are the source(s) of drinking water?

- Locations of
- surface water
- intakes for
- drinking water

## Building the Cumulative Assessment

- NW Fruitful Rim: GW dominates in ID; SW in OR

- Locations of
- surface water
- intakes for
- drinking water

## Building the Cumulative Assessment

- How vulnerable are surface water sources of drinking water in OP use areas?

- Source for runoff map:
- USDA (Kellogg)

## Building the Cumulative Assessment

- NW Fruitful Rim: More runoff in Willamette Valley

## Building the Cumulative Assessment

- How vulnerable are ground water sources of drinking water in OP use areas?

- Source for leaching map:
- USDA (Kellogg)

## Building the Cumulative Assessment

- NW Fruitful Rim: Greater leaching potential in eastern Washington

## Building the Cumulative Assessment

- Sources of monitoring: NAWQA study units

## Building the Cumulative Assessment

- NAWQA study units in the NW Fruitful Rim

## Fruitful Rim, NW 

- Surface Water: Willamette Valley
- Orchards, vegetables, sweet corn, mint
- Pesticides include Chlorpyrifos  Diazinon  Ethoprop Dimethoate  Disulfoton  Malathion Methidathion ODM Phosmet  AZM

- Ground Water: eastern WA, southeast ID
- Orchards (WA)
- Potatoes (ID)

## Heartland

- Surface Water: vulnerability                                    greater in southern half of                                region
- Corn
- Pesticides included in analysis:
- Chlorpyrifos
- Terbufos
- Phorate
- Methyl-parathion
- Chlorethoxyfos

## Refined Water Assessment

| Individual Chemical Screen | Cumulative OP Assessment |
| --- | --- |
| Maximum label rates & frequency, minimum intervals | Typical usage rates, frequencies, intervals |
| Single compound | Multiple compounds considering only valid co-occurrence |

## Accounting for Cropping Area

## Application Rates

- Typical vs. Maximum Label Rates
- Rate
- Frequency
- Interval
- Direct relationship between amount of pesticide applied and amount reaching water
- Reflects regulatory actions that have been taken

## Distribution of Daily Estimates

- In each assessment area, we need to know
- What crops with OP-use occur together?
- What OPs are used in the same time frame?
- Where multiple OPs do occur together in time and place, we must weight their relative contributions
- Cropped area coverage
- Usage

## Approach for Ground Water

- Regions where ground water is the predominant source of drinking water
- Florida (SE Fruitful Rim)
- Mississippi Delta (Mississippi Portal)
- Eastern WA, southeast ID (NW Fruitful Rim)
- Where high OP-use areas coincide with vulnerable ground water sources of drinking water
- Consult monitoring, assessments of aquifer, relative vulnerability of overlying soil, geology

## Results

- For each cumulative distribution...

- Volumes of documentation
- and characterization

## Cumulative Exposure

**Food**

**Water**

**Residential**
**uses**

- Water distribution is included with
- food, residential exposures as a part
- of the probabilistic assessment

## Characterization

- Area represented by regional distribution
- Extent of OP usage, drinking water sources and vulnerability
- Area expected to be less vulnerable
- “Typical” pesticide usage: may not reflect times of higher or lower usage
- Major chemical, crop contributors

## If water is a significant contributor...

- Focus on specific regions
- Extent of area represented by regional assessment
- Distributions from other area within the region
- Estimated population served
- Focus on major contributors
- Specific chemical-crop uses
- Time(s) of higher exposure
- Focus mitigation if necessary

## Accounting for Co-Occurrence

**Accounting for Co-Occurrence**

**Steve Nako**
- Health Effects Division

## Roadmap

- Development of drinking water methods
- Introduction & overview
- Probabilistic methods a necessity for cumulative
- Summary of proposed methods
**Use information:**
**Accounting for co-occurrence**
- Use information:
- Sites, crops, use patterns
- Summary and next steps

## Using a Regional Framework

- The cumulative assessment _starts_ on the regional scale
- We focused our assessments on specific locations within the region
- If drinking water is a significant contributor in any region, we will be looking at variations within the region

## Estimating Co-Occurrence in Drinking Water

- Rely upon known cropping patterns, actual pesticide use, and various agronomic publications to address pesticide use within vulnerable areas (regions)
- While many OPs are registered for use on a crop, not all OPs are applied to that crop, at the same time  (e.g., @ plant applications for control of corn rootworm)

## Estimating Co-Occurrence: Spatial Aspects

- Cumulative Adjustment Factors – account for contributions from multiple (Crop-OP) uses
- Review Issue: Regional Approach & Calendex Requirements
- Cumulative Adjustment Factors (CAF): Method & Illustration
- CAF based on known cropping patterns and pesticide use data

## Estimating Co-Occurrence: Temporal Aspects

- Pesticide Use Windows - account for timing of pesticide applications
- Review of Issue: Crops, Pests & Application Timing
- Pesticide Use Windows – based on various data sources, including state recommendation reports, crop profiles, pesticide use data and agronomic publications
- Crop/Use Matrices – assemble information, and construction pesticide use windows for specific uses

## Review Regional Framework

- USDA/ERS Farm Resource Regions
- For each region, identify specific vulnerable areas based on:
- OP usage
- Rainfall/runoff
- Other environmental factors (soil type, slope, irrigation, etc.)

## Building the Cumulative Assessment

- NW Fruitful Rim: Willamette Valley

## Review Regional Framework

- Regional assessment needs to account for multiple (Crop-OP) uses within a specific area
- Tailored regional surface water assessment around selected areas:
- Assembled environmental data
- Identified major Crop-OP combinations within that area
- Assembled pesticide use statistics for those uses in that area, such as:
- Average application rates
- Average number of applications
- Application timing

## Index Reservoir (IR) Estimates

- Index-Reservoir (IR) surface water assessments conducted for each Crop-OP use using appropriate location data:
- Pesticide usage (application rates, number of applications, application dates)
- Environmental data (rainfall, soil types, etc.)
- Chemical-specific data

## ?

- Corn – OP(B)
- Corn – OP(C)
- Corn – OP(D)
- Alfalfa – OP(A)
- Alfalfa – OP(B)
- Alfalfa – OP(E)
- Alfalfa – OP(F)
-   :    :       :    :

- Calendex
- Residue
- Concentration
- File (Water)

- Multiple Uses Within Selected Area

**?**

- The Index Reservoir (IR) estimates start with a calculation based on the (Crop-OP) use occurring throughout entire area

## 

- Corn – OP(B)
- Corn – OP(C)
- Corn – OP(D)
- Alfalfa – OP(A)
- Alfalfa – OP(B)
- Alfalfa – OP(E)
- Alfalfa – OP(F)
-   :    :       :    :

- Calendex
- Residue
- Concentration
- File (Water)

*Summation Would Overstate *
*Cumulative OP Concentration*

- Multiple Uses Within Selected Area

## Index Reservoir\Cumulative Adjustment Factor (IR\CAF)

- Objective of Index Reservoir\Cumulative Adjustment Factor (IR\CAF) approach:
- Use all available information about a vulnerable area to appropriately adjust the (IR) estimated daily water concentrations from each use (Crop-OP)

## Index Reservoir\Cumulative Adjustment Factor (IR\CAF)

- Each IR output is adjusted to account for the relative acres treated.  Adjustment factors include consideration that:
- Not all land in vulnerable area is agricultural
- Not all agricultural land is planted to OP crops
- Not all OP crops are actually treated with OP’s
- Pesticide use patterns are specific to the area
- Those OP crops which are treated with OP’s are treated at specific rates, at specific times, and with specific frequencies

## Cumulative Adjustment Factors (CAF) are applied to each Index Reservoir output to account for the corresponding area treated:

CAFCORN-OP(A)  =
PCAOP CROPS x (Acres TreatedCORN-OP(A) / Total Acres PlantedAll OP Crops ) 

where PCAOP Crops  = (Total Acres PlantedAll OP Crops / Total Acres)

	The example below illustrates this CAF adjustment

- Cumulative Adjustment Factors (CAF) are applied to each Index Reservoir output to account for the corresponding area treated:
- CAFCORN-OP(A)  =
- PCAOP CROPS x (Acres TreatedCORN-OP(A) / Total Acres PlantedAll OP Crops )
- where PCAOP Crops  = (Total Acres PlantedAll OP Crops / Total Acres)
- 	The example below illustrates this CAF adjustment

## Illustration of CAF Adjustments

| Site | Total Acres |
| --- | --- |
| Total Area | 800,000 (100%) |
| Non-Ag | 200,000 (25%) |
| All OP Crops | 320,000 (40%) |
|   Corn (OP) | 200,000 |
|   Alfalfa (OP) | 80,000 |
|   Apples (OP) | 24,000 |
|   Beans (OP) | 16,000 |
| Non-OP Crops | 280,000 (35%) |

- CAFOP Crops = (Total Acres PlantedAll OP Crops / Total Acres) = 320,000/800,000 = 40%

## Hypothetical Illustration of CAF Adjustments

| OP | Area Treated, By Crop (Acres Planted) |  |  |  |  |
| --- | --- | --- | --- | --- | --- |
|  | Corn
(200,000) | Alfalfa
(80,000) | Apples
(24,000) | Beans
(16,000) | Total
(320,000) |
| A | 60,000 | 16,000 | 10,000 |  | 86,000 |
| B | 1,000 | 4,000 |  | 16,000 | 21,000 |
| C | 500 |  |  |  | 500 |
| D | 40,000 |  |  |  | 40,000 |
| E |  | 10,000 |  | 1,000 | 11,000 |
| F |  | 8,000 | 15,000 |  | 23,000 |
| G |  |  | 6,000 | 16,000 | 22,000 |
| H |  |  | 6,000 | 2,000 | 8,000 |
| SUM | 101,500 | 38,000 | 37,000 | 35,000 | 211,500 |

## Illustration of CAF Adjustments

| OP | Area Treated, By Crop (Acres Planted) |  |  |  |  |
| --- | --- | --- | --- | --- | --- |
|  | Corn
(200,000) | Alfalfa
(80,000) | Apples
(24,000) | Beans
(16,000) | Total
(320,000) |
| A | 60,000 | 16,000 | 10,000 |  | 86,000 |
| B | 1,000 | 4,000 |  | 16,000 | 21,000 |
| C | 500 |  |  |  | 500 |
| D | 40,000 |  |  |  | 40,000 |
| E |  | 10,000 |  | 1,000 | 11,000 |
| F |  | 8,000 | 15,000 |  | 23,000 |
| G |  |  | 6,000 | 16,000 | 22,000 |
| H |  |  | 6,000 | 2,000 | 8,000 |
| SUM | 101,500 | 38,000 | 37,000 | 35,000 | 211,000 |

**CAF****CORN-OP(A)**
- = (Total Acres PlantedAll OP Crops / Total Acres)
- x (Acres TreatedCORN-OP(A) / Acres PlantedAll OP Crops )
- = (320,000/800,000) x (60,000/320,000)
**= 7.5%**

## Illustration of CAF Adjustments

- Non-OP Crops

- Non-Ag

- Cumulative Adjustment Factor  for Corn-OP(A):
- CAF Corn-OP(A) = 7.5%

## 

- IRCorn–OP(B) x CAFCorn-OP(B)
- IRCorn–OP(C) x CAFCorn-OP(C)
- IRCorn–OP(D) x CAFCorn-OP(D)
- IRAlfalfa–OP(A) x CAFAlfalfa-OP(A)
- IRAlfalfa–OP(B) x CAFAlfalfa-OP(B)
- IRAlfalfa–OP(E) x CAFAlfalfa-OP(E)
- IRAlfalfa–OP(F) x CAFAlfalfa-OP(F)
-   :    :       :    :

- Calendex
- Residue
- Concentration
- File (Water)

- Illustration of CAF Adjustments

## Recap: IR\CAF Approach

- Selecting a specific area to evaluate
- Multiple uses (Crop-OP) within the selected area
- Index Reservoir (IR) assessments are conducted for each Crop-OP combination based on typical pesticide use patterns (application rates, number of applications) in that area

## Recap: IR\CAF Approach

- IR starts with the calculation of use occurring throughout entire area
- Cumulative Adjustment Factors (CAF) are applied to account for the area treated
- Not all land in vulnerable area is agricultural
- Not all agricultural land is planted to OP crops
- Not all OP crops are actually treated with OP’s
- Pesticide use patterns are specific to the area
- Those OP crops which are treated with OP’s are treated at specific rates, at specific times, and with specific frequencies

## Temporal Variability in Pesticide Use

- Pesticides may be applied throughout the year
- Various factors contribute to this temporal variability, including:
- Applications to different crops/planting dates
- Timing in pest infestations
- Different pests treated

## Hypothetical

**Hypothetical**

**lbs ai**

## lbs ai

**lbs ai**

**(Hypothetical)**

## Summary:Temporal Aspects of Co-Occurrence

- Temporal Aspects (Application Timing)
- Pesticides may be applied throughout the year
- IR assessments (Crop-OP) require specific application dates
- Pesticide use windows (application dates) are constructed based on various data sources specific to area, including state recommendation reports, pesticide use data, crop profiles, agronomic publications
- Crop/Use Matrices help assemble these data, construct and present pesticide use windows

## Use Information

**Use Information**

**Leo LaSota**
- Biological & Economic Analysis Division

## Roadmap

- Development of drinking water methods
- Introduction & overview
- Probabilistic methods a necessity for cumulative
- Summary of proposed methods
- Use information:
- Accounting for valid co-occurrence
**Use information:**
**Sites, crops, use patterns**
- Summary and next steps

## Approach for Surface Water

*Approach for Surface Water*

- Modeling index reservoir with percent cropped area (IR/CAF) best currently-available tool
- Daily distributions
- Multiple years
- Multiple sites, crops
- Multiple chemicals
- Ongoing risk                                                            mitigation
***Real world use patterns***
- Make use of extensive data                                                  on individual pesticide                                                  properties

## Use Information

- Location
- Crops
- OP Pesticides
- Rates

- Number of Applications
- Method of Application
- Timing

## Crops Selected

- Based on their relative contribution to total OP usage in each specific location
- Account for approximately 95% of OP use

## Heartland(Central IL)

- Corn

## Northern Crescent(South Central PA)

- Apple
- Pear
- Peach
- Corn

- Alfalfa
- Pumpkin
- Cantaloupe

## NW Fruitful Rim(Willamette Valley OR)

- Apple
- Pear
- Cherry
- Green Beans
- Pea
- Broccoli
- Cauliflower

- Cabbage
- Cucumber
- Squash
- Onion
- Sweet Corn
- Mint
- Hazelnut

## Northern Great Plains(Red River Valley: MN,ND)

- Corn
- Wheat
- Sugar Beet
- Potato

## Prairie Gateway(Central Hills TX)

- Cotton
- Corn
- Alfalfa
- Wheat
- Sorghum

## Southern Seaboard(East Coastal Plain NC)

- Cotton
- Tobacco
- Corn
- Peanuts

## Eastern Upland(Western NC)

- Apple
- Alfalfa
- Corn

## Mississippi Portal(Southern LA)

- Cotton
- Corn
- Soybean
- Sugarcane

## SE Fruitful Rim(South Central FL)

- Tomato
- Pepper
- Cucumber
- Watermelon

- Lettuce
- Citrus
- Corn
- Sugarcane

## SW Fruitful Rim: (South Central Valley CA)

- Cotton
- Citrus
- Alfalfa
- Almond
- Walnut
- Apple
- Pear

- Peach
- Apricot
- Nectarine
- Plum
- Grape
- Sugar Beet

## SW Fruitful Rim: (North Central Valley CA)

- Corn
- Alfalfa
- Almond, Walnut
- Pear
- Peach
- Apricot
- Nectarine
- Plum
- Grape

- Asparagus
- Melons
- Cucumber
- Pumpkin
- Squash
- Tomato
- Dry beans
- Sugar Beet

## Usage Data Collected

- OP pesticide(s) used
- Application rate
- Application frequency
- Method of application
- Application timing

## Pesticides/Rates/Applications

- Based on Survey Data
- Primary Source: National Agriculture Statistic Service (NASS) Agriculture Chemical Usage Reports
- Average Usage Information

## Slide 177

## Upland Cotton: Agricultural Chemical Applications,

- Louisiana, 2000 1/
- Agricultural 	: Area 	: Appli- 	: Rate per 	: Rate per 	: Total
- Chemical 		: Applied 	: cations 	: Appl. 	: Crop Yr	: Applied
- 		: Percent 	Number 	Pounds per Acre 	1,000 lbs
- Insecticides: 		:
- Acephate 		: 41 	1.7 	0.35 	0.61 	177
- Aldicarb 		: 33 	1.1 	0.52 	0.60 	140
- Carbofuran		: 11 	1.0 	0.34 	0.34 	26
- Cyfluthrin 		: 13 	1.8 	0.03 	0.06 	6
- Cypermethrin 	: 20 	1.3 	0.07 	0.10 	14
- Dicrotophos 	: 20 	1.7 	0.27 	0.48 	69
- Dimethoate 	: 3 	1.6 	0.26 	0.43 	9
- Imidacloprid 	: 12 	1.0 	0.03 	0.03 	3
- Lambda-cyhalothrin 	: 19 	2.1 	0.02 	0.05 	7
- Malathion 		: 77 	8.6 	0.87 	7.57 	4,155
- Methamidophos 	: 4 	1.0 	0.38 	0.38 	11
- Methyl parathion 	: 4 	4.3 	0.39 	1.68 	50
- Phorate 		: 3 	1.0 	0.61 	0.65 	13
- Profenofos 		: 2 	1.5 	0.86 	1.30 	19
- Spinosad 		: 16 	3.8 	0.07 	0.28 	32
- Zeta-cypermethrin 	: 3 	1.0 	0.04 	0.04 	1
- Other Chemicals: :
- Tribufos 		: 49 	1.1 	0.68 	0.74 	258

## Pesticide Application Method/Timing

- National, regional, state and local use and usage data
- Crop profiles
- Commodity specialists

## Slide 180

## Data Compilation

- Crop/Use Matrices

## Information Gathered

- Crop stages/practices
- OP pesticide(s)
- Area applied
- Number of Applications
- Rate
- Method of application (ground/air)

## Slide 183

## Slide 184

## Slide 185

## Slide 186

## Slide 187

## Slide 188

## Primary Sources 

- USDA Agricultural Chemical Usage Reports for Field Crops, Fruits, and Vegetables
- USDA Typical Planting and Harvesting Dates for Field Crops (AH 628) and Fresh Market and Processing Vegetables (AH 507)
- Refined by local sources

## Summary &    Next Steps

**Lois Rossi**
- Director
- Special Review & Reregistration Division

## Roadmap

- Development of drinking water methods
- Introduction & overview
- Probabilistic methods a necessity for cumulative
- Summary of proposed methods
- Use information:
- Accounting for valid co-occurrence
- Use information:
- Sites, crops, use patterns
**Summary and next steps**

## Summary of Cumulative Water Assessment Methods

- Water Assessment:
- Probablistic assessment done with daily distribution of estimated residues
- Regional assessment used in order to combine water (and residential) on a realistic, localized scale
- Focuses on realistic co-occurrence
- Requires large amounts of use information which have been derived from documented information on actual use practices

## Summary of Cumulative Water Assessment Methods:Use of Available Monitoring Data

- Available monitoring data have been utilized in developing assessment
- Available monitoring data will be used as a check on the estimates at all steps in the process

## Next Steps

- All data considered for the drinking water exposure assessment will be available with the preliminary assessment
- Working with CARAT & USDA on how to enhance transparency & ease of stakeholder participation on drinking water assessment

## Next Steps

**October 4, 2001.**  CARAT Sub-Workgroup Meeting
**October 2001.**  Release various revised science policy papers
**October, November 2001.**  Technical briefing(s) on exposure methodologies
**December 2001.**  Release preliminary risk assessment; tech briefing
**Winter 2002 (Feb. 5-8 scheduled).**  SAP Meeting on preliminary risk assessment
**Winter 2002 (likely through March 8th).**  Comment period on preliminary risk assessment
**August 2002.**  Release revised risk assessment

## Next Steps

- For the most up-to-date information, visit:
- _http://www.epa.gov/pesticides/cumulative/_
- To receive OPP Updates via e-mail:
- See the sign-up sheet at the registration desk