risk assessments for exposure of deployed military personnel to insecticides used for personal...

Risk Assessments for Exposure of Deployed Military Risk Assessments for Exposure of Deployed Military Personnel to Insecticides used for Personal Personnel to Insecticides used for Personal

Protection and Disease-Vector Management Protection and Disease-Vector Management

Robert K. D. PetersonRobert K. D. PetersonMontana State UniversityMontana State University

Bozeman, MontanaBozeman, Montana

ProblemProblem• Because of the lack of vaccines and therapeutic drugs,

vector management, including the use of personal

protective measures, is the best tool that deployed

military personnel have against most vector-borne

pathogens that cause disease

• In preparation for military operations and force-health

protection, the health risks from vector-borne

pathogens that cause disease and vector

management tactics need to be understood

ProblemProblem• Due to long-standing perceptions of risk from

pesticides, the use of insecticides may raise

concerns about their potential adverse health

effects on military personnel

• The uncertainties about exposure of the troops to

pesticides led the DOD to investigate the use and

management of pesticides during the Gulf War and to

raise concerns about the potential health effects of

pesticide exposures to service members in general

ObjectiveObjective

To use risk assessment methodologies to To use risk assessment methodologies to

evaluate health risks to deployed U.S. military evaluate health risks to deployed U.S. military

personnel from insect-vector management tacticspersonnel from insect-vector management tactics

© 2004 RKD Peterson

Risk AssessmentRisk Assessment

Risk assessment is a formalized basis for Risk assessment is a formalized basis for the the objectiveobjective evaluation of risk in which evaluation of risk in which assumptionsassumptions and and uncertaintiesuncertainties are clearly are clearly considered and presented.considered and presented.

HazardIdentification

Dose-ResponseRelationships

ExposureAssessment

RiskCharacterization

Risk Assessment ParadigmRisk Assessment ParadigmP

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For

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latio

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Risk AssessmentRisk Assessment

Extremely conservative assumptionsto screen out negligible risks

Reasonable worst-case scenarios

Tier I

Tier II

Tier III

Tier IV

Most refined assessment

MethodologyMethodology

Acute Exposure:Acute Exposure:

• Single-day exposures after a single application or Single-day exposures after a single application or use of the chemicaluse of the chemical

Subchronic Exposure:Subchronic Exposure:

• The exposure per day over 180 days with multiple The exposure per day over 180 days with multiple spray eventsspray events

Chronic Exposure:Chronic Exposure:

• The exposure per day over 250 days per year for The exposure per day over 250 days per year for 10 years10 years

MethodologyMethodology

Hazard Identification:Hazard Identification:

permethrin, resmethrin, sumithrinpermethrin, resmethrin, sumithrin

Outdoor Space SpraysOutdoor Space Sprays

BDU, BednetBDU, Bednet

SynergistSynergist

piperonyl butoxidepiperonyl butoxide

cyfluthrin, lambda-cyhalothrin,cyfluthrin, lambda-cyhalothrin,alpha-cypermethrin, sumithrinalpha-cypermethrin, sumithrin

permethrin, deltamethrin, lambda-cyhalothrin, permethrin, deltamethrin, lambda-cyhalothrin, alpha-cypermethrin, cyfluthrinalpha-cypermethrin, cyfluthrin

Indoor/Outdoor ResidualIndoor/Outdoor Residual

Insecticide-Impregnated BDU’sInsecticide-Impregnated BDU’s

• Worn 18 hr/day

• Permethrin Only

• Dermal Exposure Only

• Briefs and undershirt

• Arms, hands, and legs

• No wash-off or

degradation

Insecticide-Impregnated BednetInsecticide-Impregnated Bednet

• 8 hr/night

• permethrin, deltamethrin,

lambda-cyhalothrin, alpha-

cypermethrin, cyfluthrin

• Inhalation Exposure

• Dermal Exposure

• 50% of head, trunk, arms, legs,

hands, feet

• No wash-off or degradation

Surface Residual and Indoor Surface Residual and Indoor Space ApplicationsSpace Applications

• Surface residuals: cyfluthrin,

cypermethrin, cyhalothrin

• Indoor space spray: sumithrin

• Dermal Exposure Only

• 50% of head, trunk, arms, and

hands

• Subchronic = 6 apps/180 days

• Chronic = 9 apps/yr

AFPMB Image Database

Outdoor ULV ExposureOutdoor ULV Exposure

Inhalation: moderate activityDermal: no clothing

1-hr peak aerial concentration

Subchronic/Chronic Outdoor ULV ExposureSubchronic/Chronic Outdoor ULV Exposure

Inhalation: moderate activityDermal: no clothing

Inhalation from re-suspended soil particlesDermal exposures from contact with soilDermal exposures from contact with outdoor surfaces

30 spray events in 250 days

Surface-Residual Spray

(cyfluthrin, alpha-cypermethrin,

lambda-cyhalothrin)

Indoor Space Spray

(d-phenothrin)

Outdoor ULV Space Spray (permethrin,

resmethrin, d-phenothrin,

piperonyl butoxide)

Insecticide-Impregnated Battle Dress

Uniforms (BDUs)(permethrin)

Insecticide-Impregnated

Bednets(permethrin,

cyfluthrin, lambda-cyhalothrin,

deltamethrin, alpha-

cypermethrin)

Dermal contact with sprayed

surface

Dermal contact with sprayed

surface

Inhalation from spray particles

Dermal contact with spray particles

Inhalation exposures from re-suspended outdoor

soil particles

Dermal exposures from contact with

soil

Dermal exposures from contact with outdoor surfaces

Dermal contact with BDU

Dermal contact with bednet

Inhalation from bednet

Ap

pli

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ype

Exp

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ath

way

s, R

oute

s, a

nd

Du

rati

ons

(acute, subchronic, chronic) (acute, subchronic, chronic) (acute, subchronic, chronic) (acute, subchronic, chronic) (acute, subchronic, chronic)

(acute, subchronic, chronic) (acute, subchronic, chronic)

(subchronic, chronic) (subchronic, chronic)

(subchronic, chronic)

MethodologyMethodology

Toxicity Endpoints:Toxicity Endpoints:

Chosen based on EPA regulatory endpointsChosen based on EPA regulatory endpoints

Inhalation and dermal toxicity endpoints used for Inhalation and dermal toxicity endpoints used for respective exposure route and durationrespective exposure route and duration

No-Observed-Adverse-Effect-Level (NOAEL) No-Observed-Adverse-Effect-Level (NOAEL) compared compared to estimated exposures to estimated exposures

MethodologyMethodology

Toxicity Endpoints:Toxicity Endpoints:

Permethrin Example:Permethrin Example:

Inhalation NOAEL = Inhalation NOAEL = 11 mg/kg body weight (BW)11 mg/kg body weight (BW)

Dermal NOAEL Dermal NOAEL = 500 mg/kg BW= 500 mg/kg BW

Risk CharacterizationRisk Characterization

Integration of toxicity and exposureIntegration of toxicity and exposure

Margin of Exposure Method (MOE)Margin of Exposure Method (MOE)

NOAELNOAEL

ExposureExposure

If If MOEMOE > 100 > 100, then it is typically below , then it is typically below level of concern (LOC)level of concern (LOC)

MOE =MOE =

ResultsResultsSurface Residual and Indoor SpaceSurface Residual and Indoor Space

Chemical Application rate

Subgroup Acute Subchronic Chronic

MOE MOE MOE

Cyfluthrin 215.8 mg/m2 Adult male 139 4,173 1,434,203

Adult female 147 4,420 1,519,148

Lambda-cyhalothrin

120.56 mg/m2 Adult male 26 791 267,416

Adult female 28 838 283,255

Alpha-cypermethrin 125.9 mg/m2 Adult male 2,021 30,308 12,291,542

Adult female 2,140 32,103 13,019,541

Sumithrin 2.15 mg/m2 Adult male 295,796 8,873,875 21,293,191

Adult female 313,315 9,399,453 22,554,336

ResultsResultsOutdoor ULV Space SprayOutdoor ULV Space Spray

Chemical Application rate

Subgroup Acute Subchronic Chronic Cancer

MOE MOE MOE Risk

PBO 0.0392 kg/ha Adult male 2,198,386 116,946 41,328,113 N/A

Adult female 1,837,092 97,727 34,572,845 N/A

Permethrin 0.0078 kg/ha Adult male 4,307 15,337 21,889 4.4 X 10-6

Adult female 4,407 15,714 22,480 4.3 X 10-6

Resmethrin 0.0078 kg/ha Adult male 42,690 123,275 1,839,329 1.6 X 10-7

Adult female 35,674 125,630 1,886,254 1.7 X 10-7

Sumithrin 0.004 kg/ha Adult male 1,357,058 495,961 7,456 N/A

Adult female 1,134,032 504,459 7,618 N/A

ResultsResultsBDU’s and BednettingBDU’s and Bednetting

Chemical Target dose Subgroup Acute Subchronic Chronic Cancer

MOE MOE MOE Risk

Permethrin(BDUs)

0.125 mg/cm2 Adult male 7,587 7,587 11,078 8.6 X 10-6

Adult female 7,594 7,594 11,087 8.6 X 10-6

Permethrin(bednets)

500 mg/m2 Adult male 2,830 8,497 12,406 7.7 X 10-6

Adult female 2,878 8,642 12,617 7.6 X 10-6

Permethrin(bednets)

60.33 mg/m2 Adult male 23,208 70,422 102,683 9.3 X 10-7

Adult female 23,550 71,621 104,400 9.2 X 10-7

Deltamethrin (bednets)

25 mg/m2 Adult male 88,601 328,495 479,602 N/A

Adult female 86,052 331,671 484,239 N/A

Lambda-cyhalothrin (bednets)

20 mg/m2 Adult male 677 2,113 3,085 N/A

Adult female 683 2,146 3,134 N/A

Alpha-cypermethrin (bednets)

40 mg/m2 Adult male 27,587 42,418 74,292 N/A

Adult female 27,905 43,124 75,525 N/A

Cyfluthrin (bednets)

50 mg/m2 Adult male 2,664 8,018 11,906 N/A

Adult female 2,707 8,154 12,107 N/A

DiscussionDiscussion

• Our risk assessments were sufficiently Our risk assessments were sufficiently

conservative and indicate that health risks to conservative and indicate that health risks to

military personnel from exposures to vector-military personnel from exposures to vector-

control insecticides and personal protective control insecticides and personal protective

measures would be lowmeasures would be low

DiscussionDiscussion

• Our results most likely do not warrant Our results most likely do not warrant

significant refinements for regulatory decision-significant refinements for regulatory decision-

making, but data on actual use patterns, timing making, but data on actual use patterns, timing

and areas treated, and data on actual air and areas treated, and data on actual air

concentrations and deposition rates would concentrations and deposition rates would

better characterize risksbetter characterize risks

DiscussionDiscussion

Approach allows for the comparison of risks between Approach allows for the comparison of risks between vector-borne diseases and vector management vector-borne diseases and vector management

strategies strategies

AcknowledgmentsAcknowledgments

U.S. Armed Forces Pest Management U.S. Armed Forces Pest Management Board's Deployed War Fighter Board's Deployed War Fighter Protection Research ProgramProtection Research Program

Montana Agricultural Experiment Montana Agricultural Experiment Station, MSU Station, MSU

Thank YouThank You

bpeterson@montana.edu