Transcript Pesticide Risk Assessment

Pesticide Risk Assessment
What is FIFRA?
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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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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
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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 Animals
Test
Species
Exposure
Endpoint
LD50
Bobwhite/
Mallard
Bobwhite/
Mallard
Bobwhite/
Mallard
Single oral
Mortality
LC50
Repro.
5-d Dietary Mortality
10-wk
Dietary
LOEC,
NOEC
Toxicity Tests: Aquatic Animals
Test
Species
LC50 Rainbow, bluegill,
sheepshead
LC50 Daphnia, mysid,
eastern oyster
ELS Fathead,
Rainbow,
Sheepshead
Life Daphnia, mysid,
Cycle fish spp.
Exposure Endpoint
96 h
Mortality
48-96 h
Mortality
30-100 d LOEC,
NOEC
21-300 d LOEC,
NOEC
Toxicity Tests: Terrestrial
Invertebrate
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Honey bee
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Acute oral LD50
Acute dermal LD50
Residue studies LD50
Toxicity Test: Plants
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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
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Registrant generated test to satisfy
registration requirements for other
countries
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OECD Studies:
 Beneficial arthropods
 Soil microorganisms
 Formulation/mixture studies
 Metabolite studies
Human Health Toxicity Studies
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Rat LD50
2 generation chronic rat
90-day sub-chronic rat
Inhalation (rat/mouse)
Dermal (rabbit)
Other Sources of Toxicity
Information
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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
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www.epa.gov/pesticides/
Laboratory Environmental
Fate Studies
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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)
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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
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Field Dissipation - evaluate pesticide
mobility, degradation and dissipation
under actual use conditions
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agricultural, aquatic, forestry
Field Volatility - evaluate pesticide
movement when volatilization is concern
Dislodgeable residue
Chemical/Physical Studies
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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
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Terrestrial:
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Aquatic:
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Kenaga Nomogram
Monitoring Data
GENEEC
PRZM/EXAMS
Monitoring Data
Terrestrial/Aquatic:
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AgDrift
Kenaga Nomogram Review
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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
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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
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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
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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 userdefined waterbodies
Factors that affect drift
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Droplet size distribution
Wind speed/direction
Release height
Application method
Environmental factors (temperature,
humidity)
GENEEC Input Parameters
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Application Rate
Koc
Application Method
# of applications
Application Interval
Depth of
Incorporation
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Aerobic Aquatic
Metabolism
Solubility
Aquatic Photolysis
Hydrolysis
Aerobic Soil
Metabolism
GENEEC Aquatic Screening
Model Assumptions
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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:
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Based on contributions from AgDrift
Atrazine estimated environmental
concentrations (1 lb/ai)
12
Aerial (Koc = 39)
Aerial (Koc = 155)
Ground (Koc = 39)
Ground (Koc = 155)
Atrazine [ug/l]
10
8
6
4
2
0
0
20
40
Days
60
80
100
PRZM/EXAMS Aquatic Exposure
Model
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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
Model
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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, 21day and 60-day average.
The 1 in 10 year maximum value is used
in calculating risk quotient values
Use of Monitoring Data in Pesticide
Risk Assessment
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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
Temporal variability of atrazine and
chlorpyrifos in water and sediment
Risk Presumption for
Terrestrial Animals
Risk Presumption
RQ
LOC
Acute High Risk
EEC/LC50 or LD50/ft2
0.5
Acute Restricted
Use
Acute Endangered
Species
Chronic RQ
EEC/LC50 or LD50/ft2
0.2
EEC/LC50 or LD50/ft2
0.1
EEC/NOEC
1
LOC and Dose Response
120
100
Pesticide A
Pesticide B
% Mortality
80
60
40
20
LOC
LC50
0
0
2000
4000
6000
Concentration [ppm]
8000
10000
12000
Risk Presumption for Aquatic
Animals
Risk Presumption
RQ
LOC
Acute High Risk
EEC/LC50 or
EC50
EEC/LC50 or
EC50
EEC/LC50 or
EC50
EEC/NOEC
0.5
Acute Restricted Use
Acute Endangered
Species
Chronic RQ
0.1
0.05
1
Risk Presumption for Terrestrial
Plants
Risk
RQ
LOC
Presumption
Terrestrial and semiaquatic plants
Acute high risk
EEC/EC25
1
Acute ES
EEC/NOEC
1
Aquatic plants
Acute high risk
EEC/EC50
1
Acute ES
EEC/NOEC
1
Exceedance of LOC’s in the
Screening Assessment
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Request additional effects data
Request additional environmental fate
data
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Ex. aerobic aquatic metabolism, foliar
dissipation
Use higher tier modeling/monitoring to
refine exposure analysis and provide site
specific exposure distribution
NAWQA Maximum Atrazine
Concentrations for 40 Agricultural
Sites
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* Mortality in Phytoplankton & Macrophytes Estimated to Occur at
32 µg/L
* Invertebrate Populations Likely to be Reduced at 22 µg/L
* Mortality to Macrophytes Estimated to Occur at 18 µg/L
* Reduction in Primary Production Likely to Occur at 10 µg/L
* Reduction in Primary Production Likely to Occur at 2.62 µg/L and
Reductions in Primary Productivity & Macrophytes Estimated to
Occur at 2.3 µg/L
120
Measured Concenrations (ug/L)
110
100
90
80
70
60
50
40
30
20
10
0
0
10
20
30
40
50
Exceedence %
% Sites w/ Atrazine Concs >= Y
Source: Reregistration Eligibility Decision: Environmental Fate and Effects Chapter. 2002.
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EPA-OPP Risk Mitigation for Fish
and Wildlife
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Eliminate use on specific crop
Buffer zones
Time of application
Application method and rates
Number of applications
Spray drift best management practices
METHAMIDAPHOS
450
grass <20cm
Concentration (ppm)
400
350
grass >20 cm
300
leaves, insects
250
seeds, fruits
200
.
150
Avian LC50
(42 ppm)
100
Egg shell effects
(5 ppm)
50
Mammal survival
(33 ppm)
0
1
8
15
Days
22
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OPP Endangered Species
Protection Program (ESPP)
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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
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Service currently working with OPP to
review ESPP