D. Health Risk Assessment Methodology and Exposure Scenarios

1. Introduction

As part of this investigation, we performed a retrospective health risk assessment (HRA) of pesticide use by land-based servicemembers deployed to the Gulf. This highly technical report is presented in its entirety as Tab D. The purpose of the HRA is to provide an estimate of the likelihood of certain specific effects from pesticide exposures during the Gulf War. Such effects would have been limited to the time of deployment, and may or may not have implications for long-term health effects. Exposure means pesticide contact mainly with the skin, digestive tract, or lungs.

2. What the HRA Tells Us

The HRA identifies groups who, because of their occupational specialty, may have been at greater risk for adverse health effects arising from overexposures to pesticides. If the assumptions of the HRA are accurate, some US personnel may have been exposed to levels of pesticides that would be considered unhealthful when evaluated by current risk assessment methods. Some levels judged unhealthful today would have been considered acceptable by competent authorities in 1990-1991. Importantly, investigators uncovered no evidence that the majority of veterans were exposed to unhealthful levels of pesticides. As determined in the previous section, few veterans experienced symptoms or witnessed signs of pesticide overexposure.

3. What the HRA Does Not Tell Us

The HRA alone does not prove either that pesticide overexposures occurred during the Gulf War, or that any connection exists between pesticide exposures and chronic health effects months or years after exposure. Conversely, the HRA does not discount a possible role for pesticides in causing or contributing to some of the as-yet undiagnosed illnesses reported by some veterans.

There is scientific evidence from other published sources that repeated and prolonged exposure to organophosphate pesticides or similar chemicals at levels high enough to cause severe signs and symptoms at the time of exposure may lead to neurological problems lasting months or years beyond exposure. The HRA does not provide evidence that such problems occurred, and information obtained from veteran interviews describing acute symptoms suggests that fewer than 10 veterans sought medical treatment for pesticide exposures.

It is possible that some of those exposed to the highest levels of organophosphate and carbamate pesticides may have experienced subtle effects to the nervous system during deployment. The HRA does not provide evidence that such effects occurred. In nearly all cases, the veteran would have been unaware of any effects, and would probably have experienced no lingering health effects. In a few cases, the veteran may have experienced some mild symptoms of overexposure, such as a temporary cough, burning eyes, and runny nose. Even in these cases, we expect most or all of those exposed would have quickly recovered, without lingering health problems.

The HRA does not fully address certain combined exposures that may be of importance, such as simultaneous exposures to multiple pesticides or pesticides plus pyridostigmine bromide (PB). It also does not account for how DEET may influence absorption of other pesticides and PB, possibly increasing toxicity.

We have not included a health risk assessment for flea and tick collars in this report because they were cited by only three percent of the survey respondents and in only five percent of the PM interviews. That is, they fell below the selection criteria for inclusion (see Tab D). Additionally, we had no specific information on which of the numerous active ingredients were present in the collars used by servicemembers. However, information now available from EPA indicates that some individuals could have absorbed consequential doses of pesticides under some circumstances. For example, if servicemembers wore multiple dichlorvos-containing collars, if they wore them around their necks, and if several personnel wore them inside shared quarters, consequential inhalation exposures may have resulted for the wearers and those sharing their quarters. In a recent risk assessment of dichlorvos-containing pet collars worn by pets, EPA determined that all inhalation exposures for human adults exceeded levels of concern.[124] In another risk assessment of chlorpyrifos-containing pet collars worn by dogs, EPA determined that dermal exposures for adult humans, due to handling the collars and petting the animals, exceeded levels of concern.[125] Presumably, humans wearing such collars would absorb even higher doses. Both dichlorvos and chlorpyrifos were probably in the flea collars on the US market during the Gulf War.[126]

4. Data Collection

The HRA is based on a scientific survey of 2,005 randomly selected Gulf War veterans, interviews with 322 preventive medicine and other knowledgeable personnel, military supply records, military pesticide guidance, and available operational data. We identified 37 active ingredients probably used in the Gulf, and selected 15 pesticide products for detailed analysis based on criteria, including toxicity. These 15 products contained 12 different active ingredients.

5. Exposure Scenarios

In the HRA, we estimated the dose of each pesticide a veteran may have received. To calculate the dose for those who were exposed, we developed exposure scenarios—descriptions of how a veteran might have been exposed to a pesticide, such as breathing pesticide fumes in a tent. We developed separate exposure scenarios for the general military population and for pesticide applicators, to account for the different types of exposures. For each scenario, there are three possible routes of exposure: dermal (pesticide touches skin), inhalation, and oral (pesticide swallowed after unintentional hand-to-mouth contact). Although there are an infinite number of possible exposure scenarios, investigators developed a limited number representative of the range of exposures that may have occurred for each of the 15 POPCs. Data evaluation indicated that between 10 and 40 percent of Gulf War veterans had little to no exposure to pesticides. For the population exposed to pesticides, investigators developed low-, medium-, and high-exposure scenarios for each pesticide product. The low-exposure scenario covers the 10 percent least exposed; the medium-exposure scenario covers the bulk of the exposed population (about 80 percent); and the high-exposure scenario covers the 10 percent exposed to the highest pesticide concentrations. Investigators attempted to develop realistic exposure scenarios, but when in doubt, made assumptions that overestimated exposures.

6. Toxicity of the POPCs/Levels of Concern

The EPA supplied the toxicity information on the active ingredients contained in 14 of the 15 POPCs. The manufacturer supplied the information for the other POPC, azamethiphos. For each POPC and exposure scenario or combinations thereof, we defined a level of concern using the toxicity information we acquired. The level of concern for each pesticide is defined as the level at or below which health effects are unlikely to occur (for details, see Tab D). The higher the exposure above the level of concern, the greater the likelihood of health effects occurring. Additionally, exposures above the level of concern do not mean that health effects are guaranteed.

7. General Military Population Exposures

We relied on various sources to construct the exposure scenarios. For example, with DEET the number of applications came from the RAND pesticides survey. We assumed DEET covered one-fourth of the entire body, based on information from EPA. The number of days per month DEET was used came from the survey, and the number of months came from the preventive medicine interviews. The scenarios for all the pesticides were developed in this way; the specifics for all pesticides are provided in Tab D.

a. Personal Use Pesticides

About half of the servicemembers in the Gulf used DEET repellents. The preparations most commonly available in the Gulf were a stick (33% DEET), a lotion (33% DEET), and a liquid (75% DEET).

In the low-exposure scenario, the servicemember applied DEET once a day, 4 days each month for 2 months. In the medium-exposure scenario, the servicemember applied DEET twice a day, 15 days each month over a period of 4.5 months. In the high-exposure scenario, the servicemember applied DEET seven times a day, 24 days a month for 8 months.

About 44% of servicemembers in the Gulf used permethrin spray—mainly on battle dress uniforms, tents and mosquito nets. Normally, servicemembers waited 2 to 4 hours for the permethrin spray to dry before wearing the uniform. According to the label, servicemembers should have applied permethrin outside only; however, some veterans indicated to investigators that they did apply permethrin inside their tents.

In the low-exposure scenario, the servicemember applied one can of permethrin each day, 2 days each month for 1 month. In the medium-exposure scenario, the servicemember applied one can a day, 4 days per month for 4 months. In the high-exposure exposure scenario, the servicemember applied one can a day, 8 days per month for 8 months. We assumed servicemembers were exposed to vapors one, five, or 15 times per month in tents, since different individuals could have been spraying on different days. Servicemembers had skin exposure to permethrin present in their uniforms every day.

b. Area Spray

Up to 28% of servicemembers in the Gulf may have used d-phenothrin aerosol spray to control flies and mosquitoes inside tents and other structures. The label advised the user to spray the area for no more than 10 seconds (1/6 of a can) per 1,000 cubic feet, to then close the area for 30 minutes, and finally to ventilate the area before personnel reentered. Individuals used this pesticide with little or no supervision. Since we lacked specific information about how well servicemembers followed label instructions, we assumed that they remained inside the structures during and after application.

In the low-exposure scenario, the servicemember sprayed a tent or other enclosed area with about three-fourths of a can of d-phenothrin per day, 2 days per month for 2 months. In the medium-exposure scenario, the servicemember sprayed about three-fourths of a can per day, every day of the month for 4 months. In the high-exposure scenario the servicemember sprayed a tent with three cans per day, every day of the month for 6 months.

c. Fly Baits

The most commonly used fly baits in the Gulf were 1% methomyl (locally purchased and issued by the military) and 1% azamethiphos (the locally purchased Snip). Fly baits may have been used in areas where personnel worked, ate, or slept, and were often placed in open containers inside and outside buildings and tents, or spread on the ground. Military guidance and the labels on the EPA-registered products authorized outdoor use only. The label on Snip indicated some indoor uses. Fly baits were applied variously by trained pesticides personnel, field sanitation teams, and untrained personnel (e.g., food service personnel, and individual servicemembers).

Approximately 12% of servicemembers in the Gulf applied or were exposed to fly baits. The preventive medicine interviews showed that the Army used azamethiphos baits about as often as methomyl. The Marine Corps and the Navy used methomyl-based baits more than twice as often as azamethiphos-based baits. The Air Force apparently used methomyl almost exclusively. Exposures occurred both when the bait was applied and when servicemembers were in the vicinity of the applied baits. Investigators developed the exposure scenarios from survey information and preventive medicine interviews.

In the low-exposure scenario, the servicemember distributed one pound per day, 1 to 4 days each month for 1 to 3 months. In the medium-exposure scenario, the servicemember distributed two pounds per day, 22 days per month for 5 months. For this scenario, investigators assumed that the servicemember could either inhale the pesticide dust or absorb the pesticide contacting the skin. In the high-exposure scenario, the servicemember distributed four pounds per day, 30 days per month for 9 months. Investigators assumed the servicemember could inhale the pesticide, absorb it through the skin, or ingest it via unintentional hand-to-mouth contact.

d. Pest Strips

Approximately 7% of servicemembers in the Gulf were exposed to pest strips containing 20% dichlorvos hung in various indoor locations to control flying insects. The pest strip label recommended one strip per 1,000 cubic feet, equating to one strip per small general-purpose tent or two strips per medium general-purpose tent.

In the low-exposure scenario, the servicemember inhaled dichlorvos fumes 3 hours per day, 23 days per month for 2 months. In the medium-exposure scenario, the servicemember inhaled the fumes 11 hours per day, 27 days per month for 4 months. In the high-exposure scenario, the servicemember inhaled the fumes 16 hours per day, 30 days per month for 6 months.

e. Field Use Pesticides

The general military population was also exposed to pesticides applied by professional certified and trained applicators and field sanitation teams. Applicators used sprayed liquids, a sprayed powder, or fogging agents. The concentrations prior to dilution are listed below.

Applicators diluted liquid pesticides with water, and sprayed them on the outside base of walls or tents, around garbage containers, inside structures such as in and around cracks and crevices where the walls met the floors, and other places where pests congregated. The four sprayed liquids used were chlorpyrifos 45%, diazinon 48%, malathion 57%, and propoxur 14.7%.

Under the low- and medium-exposure scenarios, exposure to chlorpyrifos, diazinon, and malathion occurred only outdoors. Since treated areas outside would have usually been limited to building and tent foundations, and garbage containers, there would have been little opportunity for exposure following application. In the high-exposure scenario, servicemembers were exposed for 2.5 hours a day for up to 9 months in dining facilities and latrines. Exposure occurred by skin contact with treated surfaces, and inhalation of vapors.

Propoxur was applied outdoors only under the low-exposure scenario. In the medium-exposure scenario, servicemembers were exposed to propoxur for 2.5 hours a day, 4 days per month for 3 months. In the high-exposure scenario, servicemembers were exposed to propoxur for 2.5 hours a day, 10 days a month for 7 months.

The powder, bendiocarb 76%, was diluted with water and sprayed on the outside base of walls or tents, the outside of garbage containers, and other places where pests congregated. Bendiocarb was also sprayed inside structures in cracks and crevices where walls met the floors. In small structures, like latrines, the spray may have covered much of the interior surface of the structure below waist level. Servicemembers were exposed through inhalation of the vapors and skin contact on pesticide-contaminated surfaces in dining facilities and latrines.

Under the low-exposure scenario for bendiocarb, exposure occurred only outdoors. Since treated areas outside would have usually been limited to building and tent foundations, and garbage containers, there would have been little opportunity for exposure following application. In the medium-exposure scenario, bendiocarb was applied indoors, servicemembers were exposed for 2.5 hours a day, 6 days per month for 4 months. In the high-exposure scenario, servicemembers were exposed for 2.5 hours a day, 12 days a month for 7 months.

Fogging agents, including chlorpyrifos 19% and malathion 91%, were applied without dilution outdoors to control filth flies, sand flies, and mosquitoes. Fogging trucks discharged the fog outside living quarters, mess tents, or latrines. The Navy/Marines and the Air Force primarily used fogs. The general population may have been exposed by inhalation.

In the low-exposure fogging scenario, servicemembers had a single 30-minute exposure. In the medium-exposure scenario, servicemembers were exposed for 0.5 hour each day, 4 days per month for 4 to 5 months. In the high-exposure scenario, servicemembers were exposed for 0.5 hour per day, 16 days per month for 8 months.

8. Pesticide Applicators Exposures

a. Field Use Pesticides

Applicators used sprayed liquids, a sprayed powder, and fogging agents. The concentrations indicated are prior to dilution. The four sprayed liquids used were chlorpyrifos 45%, diazinon 48%, malathion 57%, and propoxur 14.7%. These pesticides were used predominantly outdoors to control filth flies, sand flies, mosquitoes, fleas, and ticks. Outside, applicators applied liquid pesticides to the base of walls or tents, garbage containers, and other places where pests congregated. Applicators also applied pesticides inside structures along cracks and crevices. In latrines, much of the interior surface below waist level may have been treated. Investigators calculated applicator exposures separately for the 2-gallon handwand sprayer and the backpack sprayer. Applicators were exposed when filling the sprayer and during use.

In the low-exposure scenarios, applicators were exposed while wearing appropriate personal protective equipment (PPE), and preparing and applying 1 gallon of diluted pesticide on a single occasion. In the medium-exposure scenario, applicators were exposed while wearing appropriate PPE, preparing and applying 5 gallons of spray per day for 4 to 13 days per month over a period of 4 to 5 months. Under the high-exposure scenario, unprotected applicators prepared and applied 40 gallons of spray per day, every day for 7 to 9 months.

Applicators mixed the powder bendiocarb 76% with water, then applied the mixture with a 2-gallon handwand sprayer. Otherwise, the use and exposure scenarios are very similar to the sprayed liquid pesticides.

In the low-exposure scenario, applicators in appropriate PPE mixed and applied 1 gallon of bendiocarb spray on a single occasion outdoors. In the medium-exposure scenario, applicators in appropriate PPE mixed and applied 5 gallons of bendiocarb spray indoors each day, 6 days per month for 4 months. In the high-exposure scenario, unprotected applicators mixed and applied 15 gallons of bendiocarb each day, 12 days per month for 7 months.

Applicators applied the fogging agents chlorpyrifos 19% and malathion 91% outdoors to control flies and mosquitoes. Applicators were exposed while loading the pesticide into the tank of a fogging truck. Fogging occurred outside living quarters, mess tents, and latrines. The size of the area treated distinguishes the low-, medium-, and high-exposure scenarios. The Navy, Marine Corps and the Air Force applicators primarily used fogs.

In the chlorpyrifos low-exposure scenario, applicators wore appropriate PPE while mixing and applying 3.5 gallons of chlorpyrifos on a single occasion. In the medium-exposure scenario, applicators wore appropriate PPE while mixing and applying 7 gallons of pesticide each day, 8 days per month for 4 months. In the high-exposure scenario, unprotected applicators mixed and applied 14 gallons of chlorpyrifos each day, 21 days per month for 8 months.

In the malathion low-exposure scenario, applicators wore appropriate PPE while mixing and applying 8 gallons of pesticide on a single occasion. In the medium-exposure scenario, applicators wore appropriate PPE while mixing and applying 52 gallons of malathion each day, 10 days per month for 5 months. In the malathion high-exposure scenario, unprotected applicators mixed and applied 120 gallons of malathion every day for 8 months.

b. Delousing Powder

US forces used lindane primarily for delousing enemy prisoners of war (EPWs). Some servicemembers used lindane for treatment of clothing to control body lice, but it is likely that these exposures were significantly lower than during the EPW delousing operations. US personnel conducted delousing both outdoors and inside tents. Investigators estimate that 200 Army personnel assigned to military police units, medical units, and possibly a few other units participated in the delousing process.

Delousing procedure specified applying one or two ounces of lindane powder to clothed individuals, [127] spraying the powder beneath the clothing at the neck, sleeve, and waist openings, and then whitening the head and hair with dust, and dusting the inside of the hat.

In the low-exposure scenario, the servicemember applied lindane in the proper manner outdoors while processing 35 EPWs a day, 4 hours a day for 6 days, at a rate of 1 ounce of lindane powder per EPW. In the medium-exposure scenario, the servicemember applied lindane indoors while processing 35 EPWs a day, 9 hours a day for 32 days at 1.2 ounce of lindane powder per EPW. In the high-exposure scenario, the servicemember applied lindane indoors while processing 150 EPWs a day, 12 hours a day for 90 days at 2 ounces of lindane powder per EPW.

9. Possible Cumulative Effects

The HRA addresses some of the effects of being exposed to more than one pesticide at a time, which is relevant for some individuals. The focus is on combinations of organophosphates and carbamates, since they act on the nervous system in the same way. Investigators conducted the analysis by combining results from the medium-exposure scenarios, as these are the most reliable and pertain to potentially the largest numbers of personnel. While we could have combined the results from high-exposure scenarios, this would produce an extremely unlikely result, due to the compounding of conservatism associated with each pesticide active ingredient.

For the general military population, investigators assumed exposure to fly baits, resin strips, chlorpyrifos fog, and either propoxur EC or bendiocarb WP, depending on branch of service. Additional effects from DEET, permethrin, and d-phenothrin would be negligible under the analysis as conducted.

For pesticide applicators, investigators assumed exposure to chlorpyrifos liquid, fly bait, and either diazinon EC or bendiocarb WP, depending on branch of service. Investigators also included results for the general military population. Additional effects from DEET, permethrin, d-phenothrin, and lindane would be negligible under the analysis as conducted.

E. Findings

The Deployment Health Support Directorate integrated results from our own investigation, the HRA, the RAND survey, and the RAND literature review to complete this report. The findings of each component are described in the following subsections.

1. Review of Gulf War Records, Documents, and Related Materials

Two key findings resulting from our document review were as follows:

The low incidence of pest-borne diseases among servicemembers was attributed to a combination of factors, including establishing a comprehensive infrastructure of medical care and preventive medicine. The PM resources controlled disease-bearing pests, primarily insects and rodents, through proper sanitation procedures and pesticide use. For many units, frequent movements during tactical operations and training prevented the build up of waste dumps and the accompanying populations of rodents and insect vectors that would otherwise have been present.[128] In addition, several factors reduced the incidence of pest-borne diseases, including cooler winter conditions at the height of the KTO buildup and the nature of the barren desert where most US units deployed.[129] Under less favorable conditions the incidence of pest-borne diseases might have been greater, and it might have been necessary to apply more pesticides.

2. Veterans’ Interviews

Investigators conducted over 900 interviews using personnel registry data and other sources to identify servicemembers who, because of their military occupational specialties, were likely to be knowledgeable about pesticide use during the Gulf War. Of these interviews, 322 provided specific information related to pesticide exposure, and are therefore referred to as exposure interviews. These exposure interviews are an important basis for the health risk assessment. A subset of the exposure interviews comprised 252 interviews with preventive medicine and pest control personnel (preventive medicine interviews).

Investigators conducted the preventive medicine interviews in an attempt to identify the pesticides and the personal protective equipment veterans used, the application methods, and the possible exposures. Investigators asked physicians, entomologists, and environmental science officers about their involvement with the development of pesticide policy and procedures, their interactions with other preventive medicine personnel, normal pesticide application, unusual exposure incidents, and any concerns they may have had about pesticide use. Investigators asked Army and Navy preventive medicine specialists and technicians, as well as Air Force pest controllers, about their training, certification, and experience as applicators. Army personnel were also asked about field sanitation teams and the command support for field sanitation teams.

Findings based on the preventive medicine interviews include:

3. RAND Literature Review

The literature review conducted by RAND summarizes the existing scientific literature on the health effects of the classes of pesticides that may have affected military personnel who served in Operations Desert Shield/Desert Storm from 1990 to 1991. The study reviews the literature on the 12 pesticide active ingredients found in the POPCs, and reports on exposures or doses and related health outcomes. The review was limited to literature published or accepted for publication in peer-reviewed journals, books, government publications, and conference proceedings. Information obtained from the literature search was used to describe the acute and chronic health effects of pesticide exposure, and relate this information to the Gulf War experience. The scientific literature search completed by RAND suggests that exposure to pesticides—specifically acetylcholinesterase inhibitors such as organophosphates and carbamates—could be among the potential contributing agents to some of the undiagnosed illnesses reported by Gulf War veterans. The report also notes that it is unlikely that exposure to these pesticides is the sole explanation for the myriad of health problems reported by Gulf War veterans, as only a few of the veterans’ symptoms are uniquely characteristic of pesticide exposure alone.

Conclusions reached in the RAND report are supported by information and evidence collected from a number of subject areas including: epidemiology; genetics; toxicology; and clinical medicine. The report notes that significant uncertainties remain, especially in linking these lines of evidence with actual exposures to AChE inhibitors (including pesticides) during the Gulf War, and that more research is needed to confirm or deny a causal link between pesticides or other agents and illness among Gulf War veterans.[130] The report states:

Evidence in the literature is suggestive, but not conclusive, that pesticides, specifically AChE inhibitors such as OPs [organophosphates] and carbamates, could be among the potential contributing agents to some of the undiagnosed illnesses seen in [Gulf War veterans].[131]

Finally, the report states that although the scientific literature has implicated exposure to acetylcholinesterase-inhibiting pesticides as a contributing factor to some health problems similar to those experienced by Gulf War veterans, none of the symptoms reported are uniquely characteristic of pesticide exposure. Therefore:

[g]iven the evidence to date and the literature reviewed, it is inappropriate to rely upon exposure to pesticides, especially OPs and carbamates, as the [sole] explanation for the myriad health problems reported by [Gulf War veterans]; however, we think it equally inappropriate at this point to completely rule out pesticides as a potential contributing factor.[132]

4. RAND Survey

RAND conducted a survey of 2,005 Gulf War veterans to collect information on pesticide use during the Gulf War. The participants consisted of a random sample of officer and enlisted personnel who served on the ground, and the report identifies the pesticides used and describes the characteristics of exposure. Information collected during the veteran surveys was used primarily to assess the pesticide exposures experienced by the general US military population while serving in the KTO. Results of the survey indicate:

Cases of clear misuse of specific, identifiable pesticide products (assuming that the respondents' answers were accurate) included permethrin, d-phenothrin, lindane, and flea or tick collars. However, the number of individuals reporting use of these products was small.

Dichlorvos pest strips were sometimes hung in densities greater than recommended by the manufacturers, particularly in some eating areas and latrines.

The results of this survey and other data provide evidence for recommending the development and implementation of skill training for military personnel in the proper use of personal protective measures against pests. Surveys conducted since the Gulf War have continued to find problems in the training and application of personal protective measures.

Most servicemembers in the KTO were exposed to one or more pesticides. RAND did not find clear evidence of widespread misuse of pesticides, but smaller groups of servicemembers reportedly had unusual pesticide-use patterns, either misusing or applying unusual quantities.[133]

5. Health Risk Assessment Findings

This subsection provides the key HRA findings. The levels of concern and exposure scenarios referred to below are described in detail in Section IV.D. To complete the HRA, it was necessary to make a number of assumptions due to the unavoidable absence of key information regarding exposure.

a. General Military Population

The exposures that exceeded the levels of concern are summarized in Table 4. The personal use pesticides and d-phenothrin did not produce exposures exceeding the levels of concern.

Table 4. General military population exposures which exceeded the levels of concern

Pesticide Type

Affected Group

Active Ingredient/Class

Exposure Scenario

Fly baits Only individuals who handled (applied) fly baits

Azamethiphos (OP)

Medium, High

Methomyl (C) High
Pest strips General military population Dichlorvos (OP) Low, Medium, High 
Sprayed Liquids General military population

Chlorpyrifos (OP)

High

Diazinon (OP)

High

Malathion (OP)

High

Sprayed Powders General military population

Bendiocarb (C)

Medium, High
OP = organophosphate
C = carbamate

b. Pesticide Applicators

The exposures that are unique to applicators are summarized in Table 5. Applicators also were subject to the same exposures as the general military population.

Table 5. Applicator personnel additional exposures which exceeded the levels of concern

Pesticide

Active Ingredient/Class

Exposure Scenario

Sprayed liquids

Chlorpyrifos (OP)

High

Diazinon (OP)

Medium, High

Malathion (OP)

High
Sprayed powders Bendiocarb (C)

Low, Medium, High

Fogs

Chlorpyrifos (OP)

High 

Malathion (OP)

High
Delousing Lindane (OC) 

Medium, High

OP = organophosphate.
C = carbamate.
OC = Organochlorine.

c. Possible Cumulative Effects

Some servicemembers were exposed to more than one pesticide at a time, and may therefore had exposures that exceeded the levels of concern, even if individual exposures did not. The results of cumulative exposures are presented below.


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