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

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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