Pesticide Risk Assessment

1. Pesticide Risk Assessment

2. What is FIFRA? • Federal Insecticide, Fungicide, and Rodenticide Act • Requires pesticides sold or used in U.S. to be registered by EPA • EPA registration standard: will not cause “unreasonable adverse effects on the environment”

3. FIFRA REGISTRATION • Section 3 - Authorizes EPA to register new pesticide products • Section 4 - Reregistration of pesticides by EPA to ensure they meet current standards • Section 18 - Emergency use requests can be granted by EPA for unregistered pesticide uses • Section 24(C) - Special local needs requests can be granted by EPA for new uses of registered products

4. EPA-OPP Standard Evaluation Procedure for Ecological Risk Assessment • Assumes risk is a function of toxicity and exposure • RQ = Estimated Environmental Concentration / Toxicity Endpoint • RQ compared to levels of concern (LOC’s)

5. Toxicity Tests Terrestrial Animals

6. Toxicity Tests: Aquatic Animals

7. Toxicity Tests: Terrestrial Invertebrate • Honey bee • Acute oral LD50 • Acute dermal LD50 • Residue studies LD50

8. Toxicity Test: Plants • Aquatic plants • Blue-green and green algae (EC50) • Marine and freshwater diatom (EC50) • Duckweed (EC50) • Terrestrial plants (EC25, NOEC) • Six dicots and four monocots (crops) • Root-shoot length, weight, visual

9. Other Sources of Toxicity Information • Registrant generated test to satisfy registration requirements for other countries • OECD Studies: • Beneficial arthropods • Soil microorganisms • Formulation/mixture studies • Metabolite studies

10. Human Health Toxicity Studies • Rat LD50 • 2 generation chronic rat • 90-day sub-chronic rat • Inhalation (rat/mouse) • Dermal (rabbit)

11. Other Sources of Toxicity Information • Open Literature • Internet Sources (USGS acute toxicity test database, EXTOXNET, PAN pesticide database, WHO/FAO pesticide data sheets) • EPA-OPP “One-liner” ecotoxicity and environmental fate databases • www.epa.gov/pesticides/

12. Laboratory Environmental Fate Studies • Aerobic Soil Metabolism - rate of degradation by soil microorganisms • Hydrolysis - chemical reaction with water forming new molecule (often pH dependent) • Aqueous Photolysis - breakdown of molecules in water through the absorption of light • Aerobic and Anaerobic Aquatic Metabolism - rate of metabolism in aqueous environment with and without oxygen.

13. Laboratory Environmental Fate Studies (continued) • Kd and Koc - rate of soil adsorption • Bioconcentration Factor (BCF) - Ratio of concentration in organism (fish) compared to surrounding medium (water)

14. Field Environmental Fate Studies • Field Dissipation - evaluate pesticide mobility, degradation and dissipation under actual use conditions • agricultural, aquatic, forestry • Field Volatility - evaluate pesticide movement when volatilization is concern • Dislodgeable residue

15. Chemical/Physical Studies • Vapor pressure - measure of a chemicals volatility • Solubility - measure of ability to dissolve in a solvent (water) • Henry’s Law Constant - ratio of vapor pressure to water solubility • Octanol-water partition coefficient (Kow) - ratio of partitioning in octanol to water

16. EPA-OPP Exposure Analysis • Terrestrial: • Kenaga Nomogram • Monitoring Data • Aquatic: • GENEEC • PRZM/EXAMS • Monitoring Data • Terrestrial/Aquatic: • AgDrift

17. Kenaga Nomogram Review • Dietary exposure model for liquid broadcast applications • Determines maximum and median concentrations on various food items • Residue based on application rate and structure of plant/insect • Residues independent of application method

18. Granular, Bait, and Treated Seed Exposure Applications • In-furrow applications assume 1% of granules, bait or seed unincorporated • Incorporated banded treatments assume 15% material unincorporated • Broadcast treatment w/o incorporation assumes 100% of granules, bait, seed unincorporated

19. Terrestrial Plant Exposure Analysis • Runoff based on solubility • Drift based on standard assumptions for ground (1%) and aerial (5%) applications • Scenario based on runoff from 1-ha to adjacent hectare for terrestrial plants • Scenario based on runoff from 10-ha to adjacent hectare for semi-aquatic plants

20. AgDrift Model Summary • Model based on field and wind tunnel studies to determine drift from different application methods • Simulates ground, orchard air blast and aerial applications • Predicts off-site terrestrial and aquatic concentrations into standard or user-defined waterbodies

21. Factors that affect drift • Droplet size distribution • Wind speed/direction • Release height • Application method • Environmental factors (temperature, humidity)

22. Application Rate Koc Application Method # of applications Application Interval Depth of Incorporation Aerobic Aquatic Metabolism Solubility Aquatic Photolysis Hydrolysis Aerobic Soil Metabolism GENEEC Input Parameters

23. GENEEC Aquatic Screening Model Assumptions • Applications occur on a 10 ha field that drains into a one hectare pond 2-m in depth • No buffer between the pond and treated field • Runoff is from a single large rainfall event over a 24-hour period • Soil type is considered a high runoff soil (MS silt loam) • Drift contribution: • Based on contributions from AgDrift

24. Atrazine estimated environmental concentrations (1 lb/ai)

25. PRZM/EXAMS Aquatic Exposure Model • Site specific model that determines pesticide load from agricultural applications • Each simulation is conducted using 36 years of rainfall data to determine variability in loading • Calculates edge of field pesticide loadings in surface water and sediment

26. PRZM/EXAMS Aquatic Exposure Model • Environmental fate model that simulates the process that occur in the water body • Steady state model that has a constant volume • Calculates peak maximum, 96-hour, 21-day and 60-day average. • The 1 in 10 year maximum value is used in calculating risk quotient values

27. Use of Monitoring Data in Pesticide Risk Assessment • Typically used for currently registered pesticides (reregistration, special review) • Sources: • NAWQA – USGS • open literature • registrants • Considerations for use: • temporal and spatial sampling • storm events vs. base flow

28. Temporal variability of atrazine and chlorpyrifos in water and sediment

29. Risk Presumption for Terrestrial Animals

30. LOC and Dose Response

31. Risk Presumption for Aquatic Animals

32. Risk Presumption for Terrestrial Plants

33. Exceedance of LOC’s in the Screening Assessment • Request additional effects data • Request additional environmental fate data • Ex. aerobic aquatic metabolism, foliar dissipation • Use higher tier modeling/monitoring to refine exposure analysis and provide site specific exposure distribution

34. NAWQA Maximum Atrazine Concentrations for 40 Agricultural Sites 130 * Mortality in Phytoplankton & Macrophytes Estimated to Occur at 120 32 µg/L 110 * Invertebrate Populations Likely to be Reduced at 22 µg/L 100 * Mortality to Macrophytes Estimated to Occur at 18 µg/L * Reduction in Primary Production Likely to Occur at 10 µg/L 90 * Reduction in Primary Production Likely to Occur at 2.62 µg/L and 80 Reductions in Primary Productivity & Macrophytes Estimated to Occur at 2.3 µg/L 70 Measured Concenrations (ug/L) 60 50 40 30 20 10 0 0 10 20 30 40 50 60 Exceedence % % Sites w/ Atrazine Concs >= Y Source: Reregistration Eligibility Decision: Environmental Fate and Effects Chapter. 2002.

35. EPA-OPP Risk Mitigation for Fish and Wildlife • Eliminate use on specific crop • Buffer zones • Time of application • Application method and rates • Number of applications • Spray drift best management practices

37. OPP Endangered Species Protection Program (ESPP) • Goal is to implement mitigation measures to eliminate adverse impact to listed spp. • Currently ESPP defers to “county bulletins” • Program in place since 1989 • Voluntary BMPs for listed species • Very few county bulletins complete • Service has not consulted on county bulletins • Service currently working with OPP to review ESPP