john leahy, epa pesticide re-evaluation division risk overview why changes are needed
Post on 19-Dec-2015
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John Leahy, EPAPesticide Re-evaluation Division
Risk Overview
Why Changes are Needed
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Fumigants Are Applied Many Ways to Control a Variety of Pests
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Focus On Acute Residential Bystander & Occupational Risks
Wind blows emissions from an application to a receptor of
concern (e.g., house or school)
Wind
Other types of exposures also considered including:Dietary (methyl bromide only)Drinking water (methyl bromide only)EnvironmentalCommunity based or ambient exposures in the population
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Risk Assessment Process
Hazard IdentificationDoes the agent cause the adverse effect?
Dose-Response Assessment
What is the relationship betweendose and incidence/severity of effects?
Exposure Assessment
What exposures are currently experienced or anticipated underdifferent conditions?
Risk Characterization
What is the estimated incidencelikelihood of the adverse effectin a given population?
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Scientific Foundation
• Recognized methods used• Public peer review processes under FACA rules
• SAB on RfC inhalation risk methodology (1998)• SAP on exposure modeling (2004)
• Multi-agency collaboration• USDA• DPR• FDACS
• Based on multiple lines of evidence• Hazard data, Monitoring, Modeling, Incidents
• Refined as a result of multiple public comment periods
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Fumigant Toxicity ComparisonParameter Chloropicrin
MITC(Metam/Dazomet)
MeBr Iodomethane 1,3-D DMDS
Study used in risk
assessment
Human Eye Irritation1 hr/day
Human Odor & Eye
1-8 hr/day
Developmental Rabbit
6 hrs/day
1.Subchronic-Rat
6 hrs/day2. Develop.-
Rabbit6 hrs/day
Acute -Rat4 hrs
Special 24-hour inhalation study-rat
Endpoint Eye irritationEye irritation
response
Agenesis of gall bladder, ↑fused
sternebrae, ↓fetal wt
Degeneration of olfactory
epithelium, ↑ fetal losses
↓ body weights
Inflammation and
degeneration of the nasal olfactory
epithelium (levels II-VI); all minimal
Completeness of Database
Moderate-High Low Moderate High Moderate Moderate-High
Symptoms reported from
Incidents
Odor, eye, nasal irritation, difficulty breathing, pulmonary
edema
Eye, throat & skin irritation, nausea,
coughing
Headache, weakness, difficulty breathing,
convulsions (soil uses)
No incidentsEye, throat & skin irritation,
cough
Limited incidents, odor issues, no other
confirmed effects
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Field Emissions (Flux) Monitoring
Cross Section Of Cross Section Of
Treated Field WithTreated Field With
Known Surface AreaKnown Surface Area
Emissions Are Described As Flux Values (µg/m2/sec)
Volatile ResiduesVolatile Residues
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MeBr Field 8 Results
19A; tarped raised bed in CA
200 lb/A; 98/2 MeBr/Pic
12 hr samples; LOD 0.005 ppm
30’ – 0.52 & 0.029 ppm
430’ - ND & ND ppm
5’ 0.65
&1.0
ppm
30’ – 0.39 & 0.23 ppm
430’ – 0.028 & 0.65 ppm
30’ 0.24
& 0.005 ppm
430’ 0.042
&ND
ppm
405’ 0.46
& 0.69 ppm
288’ 0.13
& 0.21 ppm
408’ 0.089
& 0.017 ppm
430’ 0.072 & ND ppm
430’ 0.072
&0.74 ppm
Actual Flux Monitoring Results
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0%
5%
10%
15%
20%
25%
30%
0 20 40 60 80 100 120 140
Mean Time Since Application (hours)
Flu
x R
ate
(%
of
Ap
pli
ca
tio
n)
Example Emissions Profiles
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Sources Include*:
• National Weather Service (NWS)
• FAA’s Automated Surface Observing System (ASOS)
• California Irrigation Management Information System (CIMIS)
• Florida Automated Weather Network (FAWN)
Modeling5 Years of Weather Data Used
*Data from 6 stations used for analyses including *Data from 6 stations used for analyses including Ventura & Bakersfield CA; Bradenton & Tallahassee Ventura & Bakersfield CA; Bradenton & Tallahassee
FL; Flint MI; Yakima WAFL; Flint MI; Yakima WA 10
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PERFUM Model Outputs
Weather Day 1
Weather Day 2
•Solves for distance at target concentration which is defined by HEC/UF
•Uses 5 years of weather data so each analysis would contain 1825 sets of outputs
•Tallahassee & Bradenton weather used for southeast region
Treated Field
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Incident Overview• Generally, low frequency of incidents relative to
numbers of applications– Severe effects occur but low percentage of overall
incident rate
– Reports are consistent with risk assessments based on the nature of effects
– Major incidents (those involving many people) typically occur because of equipment failure, applicator error, atmospheric conditions
– Workers tend to have higher incident rates than bystanders
• “Reconstructing” incidents to examine exact factors which lead to problem can be difficult especially for bystander exposure
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Summary• Peer reviewed methods• Extensive emissions & occupational monitoring
data• Also focused on factors which impact emissions• Results indicate risk management required,
incident rates are low and effects consistent with risk assessment
• Key concern is near applications, buffers reduce those types of exposures
• Much ongoing research to evaluate emission controls (e.g., low permeability tarps & soil adjuvants)
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