risk assessments for exposure of deployed military personnel to insecticides used for personal...
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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
robl
em
For
mu
latio
n
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
cati
on T
ype
Exp
osu
re P
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
