Proposed Rule on Conventional Pesticides (40 CFR Part 158)

May 3-4, 2005Holiday Inn Rosslyn1900 N. Fort Myer DriveArlington, VA 22209

Environmental Fate and Effects Division

Environmental FateData Requirements

Office of Pesticide Programs

U.S. Environmental Protection Agency

May 4, 2005

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Purpose of Fate and Transport Assessments

� Where and how does the pesticide move in the environment – major routes of dissipation.

� How long will it persist?� What degradation products are produced and in what

quantities?� How much parent and/or degradate is likely to reach

ground water and/or surface water?

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Laboratory Studies:Degradation

� 835.2120 Hydrolysis� 835.2240 Photodegradation in Water� 835.2410 Photodegradation on Soil� 835.2370 Photodegradation in Air

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Laboratory StudiesMetabolism

� 835.4100 Aerobic Soil Metabolism� 835.4200 Anaerobic Soil Metabolism� 835.4400 Anaerobic Aquatic Metabolism� 835.4300 Aerobic Aquatic Metabolism

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Laboratory StudiesMobility and Bioaccumulation

� 835.1240 Batch Equilibrium� 835.1230 Soil Column Leaching� 835.1410 Laboratory Volatility� 850.1730 Accumulation in Fish

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Field Studies

� 835.8100 Field Volatility� 835.6100 Terrestrial Field Dissipation� 835.6200 Aquatic Field Dissipation� 835.6300 Forest Field Dissipation� 850.1950 Bioaccumulation in Aquatic Non-

Target Organisms� 835.7100 Prospective Groundwater Monitoring

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Summary

� No new tests� Codify current practices� Evolving science, FIFRA, FQPA� Peer review and public participation on significant

changes� Clarify test notes� Update “required” versus “conditionally required”

based on risk assessment experience

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Review of Laboratory Fate Studies

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Hydrolysis Studies [835.2120]

� Purpose: To establish the significance of chemical hydrolysis as a route for degradation of a pesticide and to identify the hydrolytic products formed.

� What happens to the pesticide under acidic, neutral, and alkaline environments?

� Required (R) for all use patterns except indoor where it is conditionally required (CR)

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What’s Changed?

� Proposed to be conditionally required (CR) for indoor uses

� May be required to support products for indoor uses for which environmental exposure is likely

� Longstanding practice

PHOTODEGRADATION

Aqueous Photolysis (835.2240) Soil Photolysis (835.2410)Air Photolysis (835.2370)

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Purpose of Photodegradation Studies

� Potential to degrade in water, soil, or air when exposed to sunlight

� Data on the identity, formation, and persistence of photoproducts

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What’s Changed?

� Photodegradation in Water– Proposed new test note – “Not required when the

electronic absorption spectra, measured at pHs 5, 7, and 9, of the chemical and its hydrolytic products, if any, show no absorption or tailing between 290 and 800 nm.”

– Longstanding practice

� Photodegradation on Soil– Proposed R for terrestrial and forestry uses

Previously was CR– Longstanding practice

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What’s Changed?

� Photodegradation in Air– Adding conditional requirement for greenhouse,

forestry, and residential outdoor uses– New test note – “In view of methodological

difficulties with the study, prior consultation with the Agency regarding the protocol is recommended before the test is performed.”

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Soil and Aquatic Metabolism Studies

Aerobic Soil Metabolism (835.4100)

Anaerobic Soil Metabolism (835.4200)

Anaerobic Aquatic Metabolism (835.4400)

Aerobic Aquatic Metabolism (835.4300)

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Purpose: To Provide Information On...

-Microbial degradation in soil and water systems

-Measure rate transformation of parent compound

-Provide information on the formation/decline of degradation products

-Exposure model inputs

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What’s Changed for Aerobic Soil Metabolism?

� Expanded to require for aquatic food and nonfood crop uses for aquatic sites that are intermittently dry

� Conditionally required

� Presented to the SAP in 1994

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When is the Anaerobic Soil Metabolism Study Required and What’s Changed?

� Required (R) for all terrestrial uses

� Missing from current CFR due to a printing error

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What’s Changed for Anaerobic Aquatic Metabolism?

� Proposed required (R) for terrestrial uses

� Advances in ecological risk assessment and drinking water assessments

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What’s Changed for Aerobic Aquatic Metabolism?

� Proposed required (R) for terrestrial and forestry uses

� Advances in ecological risk assessment and drinking water assessments

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Mobility Studies

Batch Equilibrium(835.1240)

Soil Column Leaching(835.1230)

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Purpose

� Will give an indication of how fast a dissolved compound will move relative to the movement of water

� Describes the distribution of pesticide between water and soil at equilibrium

� Needed for inputs to exposure models� No changes are proposed

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Laboratory Volatility(835.1410)

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Purpose of the Laboratory Volatility Studies and What’s Changed

� Determine amount and rate of volatilization under controlled conditions

� When Required– Conditionally required (CR) for terrestrial and

greenhouse uses– not required when vapor pressure < 10-6 mmHg

� No changes are proposed

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Laboratory Studies of Pesticide Accumulation in Fish850.1730

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Purpose of the Accumulation in Fish Study

� Determine if pesticide residues accumulate in fish used as human food sources

� Determine the extent of pesticides in edible portions of such fish

� Data provides information on ecological food chain exposure

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What’s Changed?

� Clarified test note about conditions for when the study is required

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Integrating Fate DataIntegrating Fate Data

Building a Conceptual Model

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The Conceptual Model

� Hypothesis developed using assumptions derived from the laboratory data

� Since lab studies evaluate specific fate and transport properties individually, they allow for the development of a conceptual model that includes only those processes that are significant.

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The Conceptual Model

� Field studies provide the primary mechanism for testing and refining the hypothesis.

� Field studies give site-specific information on the fate and transport of a pesticide and its degradates under actual use conditions.

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Field Studies

� 835.6100 Terrestrial Field Dissipation� 835.6200 Aquatic (sediment) Dissipation� 835.6300 Forestry Dissipation� 835.6400 Combination and Tank Mixes� 850.1950 Accumulation in Aquatic Non-

target Organisms

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Important

� Dissipation in the field is NOT the same as degradation of the pesticide in individual laboratory studies

� Dissipation in the field results from interaction of multiple processes at work in the entire soil and/or water system

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Dissipation can result from any one process or combination of

the following processes…

AppliedPesticide

Foliar Interception& Dissipation

Washoff

Plant Uptake

Volatilization

Transformationsmicrobialchemical

Sorption /Retention

Leaching

Surface Runoff

LateralFlow

Spray Drift

Tile Drainage

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How Do We Use Field Studies?

� Data from field studies can provide more realistic estimates of the persistence and transport of an active ingredient and its degradates

� Can reduce potential overestimation of exposure and risk and can confirm assumptions of low levels of toxic degradates

� Results can be used to propose scenario-specific effective risk mitigation

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Terrestrial Field Dissipation(835.6100)

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What’s Changed?

� Expanded conditional requirement to include aquatic sites that are intermittently dry

� Merged with the long-term field dissipation study

� Added independent laboratory validation of analytical methods

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Aquatic Field Dissipation Studies (835.6200)

� Similar scientific issues as the terrestrial field dissipation study

� Required for pesticides with aquatic uses � Conditionally required (CR) for terrestrial uses based

on potential for aquatic exposure and if pesticide residues have the potential for persistence, mobility, non-target aquatic toxicity, or bioaccumulation

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What’s Changed?

� Expanded conditional requirement to include terrestrial uses

� Clarified conditions for when study is required

� Added independent laboratory validation of analytical methods

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Forestry Dissipation(835.6300)

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What’s Changed?

� Changed from “required” to “conditionally required”

� Added independent laboratory validation of analytical methods

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Field Volatility(835.8100)

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Field Accumulation in AquaticNon-Target Organisms

(850.1950)

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Prospective Groundwater Monitoring(835.7100)

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PGW Study

� Generally triggered by drinking water concern (FQPA)

� Conditionally required (CR) for terrestrial and forestry uses

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Summary

� No new tests� Codify current practices� Evolving science, FIFRA, FQPA� Peer review and public participation on significant

changes� Clarify test notes� Update “required” versus “conditionally required”

based on risk assessment experience