Transcript Risk Assessments for Exposure of Deployed Military Personnel to Insecticides used for Personal Protection and Disease-Vector Management Robert K.

Risk Assessments for Exposure of Deployed Military
Personnel to Insecticides used for Personal
Protection and Disease-Vector Management
Robert K. D. Peterson
Montana State University
Bozeman, Montana
Problem
• 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
Problem
• 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
Objective
To use risk assessment methodologies to
evaluate health risks to deployed U.S. military
personnel from insect-vector management tactics
© 2004 RKD Peterson
Risk Assessment
Risk assessment is a formalized basis for
the objective evaluation of risk in which
assumptions and uncertainties are clearly
considered and presented.
Problem Formulation
Risk Assessment Paradigm
Hazard
Identification
Dose-Response
Relationships
Risk
Characterization
Exposure
Assessment
Risk Assessment
Tier IV
Tier III
Tier II
Tier I
Extremely conservative assumptions
to screen out negligible risks
Reasonable worst-case scenarios
Most refined assessment
Methodology
Acute Exposure:
• Single-day exposures after a single application or
use of the chemical
Subchronic Exposure:
• The exposure per day over 180 days with multiple
spray events
Chronic Exposure:
• The exposure per day over 250 days per year for
10 years
Methodology
Hazard Identification:
cyfluthrin, lambda-cyhalothrin,
alpha-cypermethrin, sumithrin
piperonyl butoxide
Indoor/Outdoor Residual
Synergist
permethrin, resmethrin, sumithrin
Outdoor Space Sprays
permethrin, deltamethrin, lambda-cyhalothrin,
alpha-cypermethrin, cyfluthrin
BDU, Bednet
Insecticide-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 Bednet
• 8 hr/night
• permethrin, deltamethrin,
lambda-cyhalothrin, alphacypermethrin, cyfluthrin
• Inhalation Exposure
• Dermal Exposure
• 50% of head, trunk, arms, legs,
hands, feet
• No wash-off or degradation
Surface Residual and Indoor
Space 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 Exposure
Inhalation: moderate activity
Dermal: no clothing
1-hr peak aerial concentration
Subchronic/Chronic Outdoor ULV Exposure
Inhalation: moderate activity
Dermal: no clothing
Inhalation from re-suspended soil particles
Dermal exposures from contact with soil
Dermal exposures from contact with outdoor surfaces
30 spray events in 250 days
Application Type
Exposure Pathways, Routes, and Durations
Surface-Residual
Spray
(cyfluthrin, alphacypermethrin,
lambda-cyhalothrin)
Dermal contact
with sprayed
surface
(acute, subchronic, chronic)
Indoor Space
Spray
(d-phenothrin)
Outdoor ULV
Space Spray
(permethrin,
resmethrin, dphenothrin,
piperonyl butoxide)
Dermal contact
with sprayed
surface
Inhalation from
spray particles
(acute, subchronic, chronic)
Dermal exposures
from contact with
outdoor surfaces
(subchronic, chronic)
(acute, subchronic, chronic)
InsecticideImpregnated
Battle Dress
Uniforms (BDUs)
(permethrin)
InsecticideImpregnated
Bednets
(permethrin,
cyfluthrin, lambdacyhalothrin,
deltamethrin, alphacypermethrin)
Dermal contact
with BDU
Dermal contact
with bednet
(acute, subchronic, chronic)
(acute, subchronic, chronic)
Dermal contact
with spray particles
Inhalation from
bednet
(acute, subchronic, chronic)
(acute, subchronic, chronic)
Inhalation
exposures from resuspended outdoor
soil particles
(subchronic, chronic)
Dermal exposures
from contact with
soil
(subchronic, chronic)
Methodology
Toxicity Endpoints:
Chosen based on EPA regulatory endpoints
Inhalation and dermal toxicity endpoints used for
respective exposure route and duration
No-Observed-Adverse-Effect-Level (NOAEL) compared
to estimated exposures
Methodology
Toxicity Endpoints:
Permethrin Example:
Inhalation NOAEL = 11 mg/kg body weight (BW)
Dermal NOAEL = 500 mg/kg BW
Risk Characterization
Integration of toxicity and exposure
Margin of Exposure Method (MOE)
MOE =
NOAEL
Exposure
If MOE > 100, then it is typically below
level of concern (LOC)
Results
Surface Residual and Indoor Space
Chemical
Cyfluthrin
Lambdacyhalothrin
Application
rate
215.8 mg/m2
120.56 mg/m2
Alpha-cypermethrin 125.9 mg/m2
Sumithrin
2.15 mg/m2
Subgroup
Acute
Subchronic
Chronic
MOE
MOE
MOE
Adult male
139
4,173
1,434,203
Adult female
147
4,420
1,519,148
Adult male
26
791
267,416
Adult female
28
838
283,255
Adult male
2,021
30,308
12,291,542
Adult female
2,140
32,103
13,019,541
Adult male
295,796
8,873,875
21,293,191
Adult female
313,315
9,399,453
22,554,336
Results
Outdoor ULV Space Spray
Chemical
PBO
Permethrin
Resmethrin
Sumithrin
Application
rate
0.0392 kg/ha
0.0078 kg/ha
0.0078 kg/ha
0.004 kg/ha
Subgroup
Acute
Subchronic
Chronic
Cancer
MOE
MOE
MOE
Risk
Adult male
2,198,386
116,946 41,328,113
N/A
Adult female
1,837,092
97,727 34,572,845
N/A
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
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
Adult male
1,357,058
495,961
7,456
N/A
Adult female
1,134,032
504,459
7,618
N/A
Results
BDU’s and Bednetting
Chemical
Target dose
Subgroup
Acute
MOE
Permethrin
(BDUs)
0.125 mg/cm2
Permethrin
(bednets)
500 mg/m2
Permethrin
(bednets)
60.33 mg/m2
Deltamethrin
(bednets)
25 mg/m2
Lambdacyhalothrin
(bednets)
20 mg/m2
Alphacypermethrin
(bednets)
40 mg/m2
Cyfluthrin
(bednets)
50 mg/m2
Subchronic
Chronic
Cancer
MOE
MOE
Risk
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
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
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
Adult male
88,601
328,495
479,602
N/A
Adult female
86,052
331,671
484,239
N/A
Adult male
677
2,113
3,085
N/A
Adult female
683
2,146
3,134
N/A
Adult male
27,587
42,418
74,292
N/A
Adult female
27,905
43,124
75,525
N/A
Adult male
2,664
8,018
11,906
N/A
Adult female
2,707
8,154
12,107
N/A
Discussion
• Our risk assessments were sufficiently
conservative and indicate that health risks to
military personnel from exposures to vectorcontrol insecticides and personal protective
measures would be low
Discussion
• Our results most likely do not warrant
significant refinements for regulatory decisionmaking, but data on actual use patterns, timing
and areas treated, and data on actual air
concentrations and deposition rates would
better characterize risks
Discussion
Approach allows for the comparison of risks between
vector-borne diseases and vector management
strategies
Acknowledgments
U.S. Armed Forces Pest Management
Board's Deployed War Fighter
Protection Research Program
Montana Agricultural Experiment
Station, MSU
Thank You
[email protected]