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Pesticide Risk Assessment. 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”. FIFRA REGISTRATION.

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Presentation Transcript
slide2

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”
slide3

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
epa opp standard evaluation procedure for ecological risk assessment
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)
toxicity tests terrestrial invertebrate
Toxicity Tests: Terrestrial Invertebrate
  • Honey bee
    • Acute oral LD50
    • Acute dermal LD50
    • Residue studies LD50
toxicity test plants
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
other sources of toxicity information
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
human health toxicity studies
Human Health Toxicity Studies
  • Rat LD50
  • 2 generation chronic rat
  • 90-day sub-chronic rat
  • Inhalation (rat/mouse)
  • Dermal (rabbit)
other sources of toxicity information11
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/
laboratory environmental fate studies
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.
laboratory environmental fate studies continued
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)
field environmental fate studies
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
chemical physical studies
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
epa opp exposure analysis
EPA-OPP Exposure Analysis
  • Terrestrial:
    • Kenaga Nomogram
    • Monitoring Data
  • Aquatic:
    • GENEEC
    • PRZM/EXAMS
    • Monitoring Data
  • Terrestrial/Aquatic:
    • AgDrift
kenaga nomogram review
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
granular bait and treated seed exposure applications
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
terrestrial plant exposure analysis
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
agdrift model summary
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
factors that affect drift
Factors that affect drift
  • Droplet size distribution
  • Wind speed/direction
  • Release height
  • Application method
  • Environmental factors (temperature, humidity)
geneec input parameters
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
geneec aquatic screening model assumptions
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
przm exams aquatic exposure model
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
przm exams aquatic exposure model26
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
slide27

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
exceedance of loc s in the screening assessment
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
slide34

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.

epa opp risk mitigation for fish and wildlife
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
opp endangered species protection program espp
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