A.4  PESTICIDE USE AND EXPOSURE[15]

A.  Introduction

During the Gulf War, US military personnel used PM resources to control pest-borne diseases. PM personnel responded to pest problems through institutional controls such as enforcing sanitation procedures, and burying or burning trash and human waste, and through the direct action of applying pesticides. Individual soldiers often used personal pesticides, both authorized and unauthorized, to control pests. In addition to the pesticides applied by US PM personnel, non-PM Coalition forces and host nation personnel also applied pesticides.

The consequences of exposure to pesticides depend on a number of factors, including: the level of each exposure; the duration of each exposure; the frequency of exposure; the route of exposure (oral, dermal, inhalation); the amount absorbed by the individual; the acute and chronic toxicity factors associated with each pesticide; and the health and nutritional status of the individual. Symptomatic exposures that occurred or may have occurred during deployment are described in Tab C-4.

A pesticide discharged as a spray directly into the air may be inhaled, ingested (swallowed), and deposited on the skin and absorbed. Regardless of the means of application, a pesticide may also be deposited on soil and surface water, or buildings, tents, and clothing. An individual may then inhale airborne forms of the pesticide (vapor or dust), may accidentally ingest material containing pesticide through routine hand-to-mouth behavior, and/or may get pesticide residues on the outer portions of the body (e.g., skin and mucous membranes). Once the pesticide contacts human tissue, it may be absorbed completely, partially, or not at all, depending in part on the chemical nature of the pesticide.

For the pesticides used in the Gulf, exposures may have occurred in a variety of ways, despite the numerous precautions required. For example, some amount of DEET would have been absorbed through the skin; much less would have been ingested; less still would have been inhaled. A small fraction of the permethrin sprayed on clothing, tents, and insect netting and helmet covers may have been absorbed through the skin, ingested, and inhaled. Pesticide fogging around troop quarters also may have contributed to a significant level of pesticide inhalation. Troops in the immediate vicinity of fly pest strips would have been exposed to low levels of pesticides via inhalation. Pesticides would have been absorbed through the skin due to the unauthorized use of pet flea and tick collars. On the other hand, the use of insect and rodent baits, and the pesticide treatment of animal carcasses and rodent burrows would be expected to contribute little toward pesticide exposure. Under conditions of inappropriate use and application, these exposures may have resulted in US troops being subjected to varying levels of pesticides that could result in adverse health effects.

In the absence of sampling data and information about pesticide application rates, which would normally have been used, investigators relied on the results of over 400 interviews with PM personnel to determine exposure levels. Of these interviews, 252 provided specific information related to exposure (e.g., frequency with which a pesticide was applied, application rates, personal protective equipment worn, etc.). An additional 60 provided information of a more general nature without the specifics relating to issues of exposure.

As indicated in Section A.2.A.4,  Gulf War Veteran Survey, this report also benefits from information collected in a veteran survey conducted by RAND. The RAND survey was commissioned to describe pesticide use by the average servicemember during the Gulf War. The RAND survey provides the best available information on what pesticides the general military population may have used for personal use, or applied in or around their living or working environment.

Investigators have not, however, been able to determine the amounts of each pesticide used during the Gulf War. Investigators were only able to find material ordering data, not actual usage data (i.e., application rates). Given the reported frequency of use and the potential toxicity, investigators identified 15 pesticide products (comprised of 12 different active ingredients) as "pesticides of potential concern" (POPC). Table 1 shows the 12 active ingredients contained in the POPCs. Table 2 provides an overview on the use and application of the POPCs. The table shows the different POPCs and their respective percent of active ingredient.

Table 2.  Pesticides use and application overview

Designation

Purpose

POPCs, Active Ingredient

Application Method

User or Applicator

Repellents

Repel flies and mosquitoes DEET 33% cream/stick By hand to skin

Individuals

DEET 75% Liquid By hand to skin, uniforms or mosquito nets
Permethrin 0.5% (P) Spray Sprayed on uniforms

Area Spray

Knock down spray, kill flies and mosquitoes

d-Phenothrin 0.2% (P) Aerosol

Sprayed in area

Fly baits, Attract and kill flies

Methomyl 1% (C) Crystals

Placed in pans outside of latrines, sleeping tents Individuals, Field Sanitation Teams, Certified Applicators

Azamethiphos 1% (OP) Crystals

Pest Strip

Attract and kill flies and mosquitoes

Dichlorvos 20% (OP) Pest Strip

Hung in sleeping tents, working areas, dumpsters

Sprayed Liquids
(emulsifiable concentrates, ECs)
Kill flies, mosquitoes, crawling insects

Chlorpyrifos 45% (OP) Liquid

Sprayed in corners, cracks, crevices

Field Sanitation Teams or Certified Applicators

Diazinon 48% (OP) Liquid

Sprayed in corners, cracks, crevices Certified Applicators

Malathion 57% (OP) Liquid

Propoxur 14.7% (C) Liquid

Sprayed Powder
(wettable powder, WP)
Kill flies, mosquitoes, crawling insects

Bendiocarb 76% (C) Solid

Fogs
(Ultra-Low Volume Fogs, ULVs)
Kill flies, mosquitoes

Chlorpyrifos 19% (OP) Liquid

Large area fogging Certified Applicators

Malathion 91% (OP) Liquid

Delousing Agent

Kill lice

Lindane 1% (OC) Powder

Dusted on EPWs, also available for personnel use

Certified Applicators, Military Police, Medical Personnel

C = Carbamates are based on carbamic acid.
OC = Organochlorines are characterized by their persistence in the environment.
OP = Organophosphates are synthetic compounds containing phosphorous.
P = Pyrethroids are synthetic compounds produced that duplicate the biological activity of the chrysanthemum plant.

Pesticides within the military supply system were all registered with the EPA. Registration, however, does not exempt individuals from following proper procedures for use and application of pesticides. The pesticide must be applied in accordance with the product label and for control of the pests listed on the label. Failure to comply with any part of the label constitutes misapplication of the pesticide.

Individuals who apply certain pesticide sprays and fogs are required to use the appropriate personal protective equipment (PPE), which may include boots, gloves, coveralls, goggles and respirators. The required PPE depends on the pesticide applied. During the Gulf War, the use of PPE by applicators varied depending on several factors, including availability, serviceability, and whether the applicator followed the guidance.

This section reports on the use and application of pesticides by US personnel during the Gulf War. This information serves as the basis for determining pesticide exposure levels that subsequently will be used in Part B of this report to predict the long-term health consequences.

B.  General Use Pesticides

General use pesticides include those issued or acquired for personal use. These included the repellents, DEET and permethrin, and d-phenothrin (an area spray for flying insects). The military supply system also issued fly control products, including fly baits and pest strips. Some personnel acquired personal use pesticides from outside the military supply system, including OFF and citronella products. In many cases these repellents were similar to those issued by the military, but with different product formulations. Additionally, veterans and official documentation indicate some personnel wore pet flea and tick collars, which were neither designed nor authorized for personal use.  The United States Central Command (USCENTCOM) and each component service generated guidance dealing with the need for protective measures against the insect threat. The CENTCOM surgeon’s office provided much of the initial PM guidance for units deploying to Operations Desert Shield/Desert Storm.

1.  Repellents

CENTCOM emphasized the "DoD Repellent System"-a properly treated and worn uniform plus the use of repellents (Figure 2).[16] Proper wear means pant legs are tucked into the boots, sleeves are rolled down, and the collar buttoned. Each service issued similar guidance. The DoD repellent system was, however, undermined by shortages of repellents and varying levels of compliance with the guidance (i.e., many personnel either did not know about the DoD Repellent System or did not take advantage of it) by individuals or theater.

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Figure 2.  DoD repellent system

A memorandum from the XVIII Airborne Corps surgeon’s office gave the Corps’ deploying soldiers some basic information to help them avoid pest threats. The memorandum expressed concern about leishmaniasis and sand fly fever and the consequent need to cover food and maintain sanitary latrines to reduce swarming sand flies, which carried both diseases.

According to the memorandum, each soldier should be issued two tubes of the 33% DEET cream (Figure 3) for the skin, and one can of permethrin aerosol for uniforms, mosquito netting, and bedding. The memorandum instructed soldiers to apply a light coat of permethrin every four or five days.[17] This guidance conflicted with guidance on the permethrin label, which instructed the user to "reapply after six weeks and sixth laundering."[18]

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Figure 3.  33% DEET, two-ounce tube

While PM personnel strongly encouraged the use of DEET and permethrin, there were shortages of these repellents and servicemembers did not always comply with guidance.

According to the RAND pesticides survey, about half of the servicemembers in the Gulf used DEET repellents.[19] The preparations most commonly available in the Gulf were a stick (33% DEET), a lotion (33% DEET), and a liquid (75% DEET). Similar preparations have been widely available to the American public for many years. The XVIII Airborne Corps had barely arrived in country before it began experiencing shortages of the repellents.[20] Shortages forced Navy and Marine units to ration DEET. Also, some Navy and Marine units had deployed with stocks of the standard 75% DEET formulation (Figure 4) which was not as long-lasting as the improved 33% formulation.[21] EPA has registered over 200 commercial DEET products. DEET products applied directly to the skin vary from 4 to 100 percent active ingredients.[22]

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Figure 4.  75% DEET, two-ounce bottle

The health consequences of exposure to DEET and permethrin, as well as the other pesticides discussed in this section are presented in Part B of this report.

About 44% of servicemembers in the Gulf used permethrin spray—mainly on battle dress uniforms (BDUs), tents and mosquito nets.[23] Normally, servicemembers waited two to four hours for the permethrin spray to dry before wearing the uniform. Individuals not involved in uniform spraying but who were in the tent at the time uniforms were treated were also subject to inhalation exposures.

Even when supplies were available, soldiers did not always comply with the guidance on DEET and permethrin.[24] Some individuals have indicated that the odor of one or both repellents was offensive, which may have resulted in decreased use.[25] Had vector-borne diseases been more prevalent, this could have been a serious shortcoming and would have had an impact on the health of affected commands.

2.  Fly Control

Fly baits, pest strips, and area sprays were in general use in the Gulf. Servicemembers used granular or crystal fly bait containing a fly attractant. The most commonly used fly baits in the Gulf were Stimukil and Snip(Figure 5). The active ingredients contained in these fly baits are1 percent methomyl and 1 percent azamethiphos, respectively. Stimukil and other fly baits containing methomyl were supplied by the military supply system. They were also purchased locally. Azamethiphos (Snip ) was acquired exclusively through local purchase.

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Figure 5.  Locally purchased fly baits: Stimukil and Snip

When flies consumed the granules, the active ingredient acted on the central nervous system to kill them. These pesticides were authorized for outdoor use only, however, the results of veterans’ interviews suggest that fly baits may have been used in any of the areas where personnel worked, ate, and slept, often placed in the open containers inside or outside buildings and tents, and even spread on the ground. Fly baits were applied by trained as well as untrained personnel and field sanitation teams.

Approximately 12% of servicemembers in the Gulf applied or were exposed to fly baits. PM personnel interviews showed that the Army used fly baits containing azamethiphos as often as those containing methomyl.[26] The Marine Corps and the Navy used methomyl-based fly baits more than twice as often as azamethiphos-based baits. The Air Force apparently used methomyl almost exclusively. Fly bait exposures occurred both when the bait was applied and when servicemembers were in the vicinity of the applied baits.

Personnel also used pest strips to control flies. Pest strips are plastic strips impregnated with the active ingredient dichlorvos. Personnel hung them in living and working areas where the strips emitted a vapor affecting the central nervous systems of flies (similar to the effect of fly baits).

The military did not specifically authorize nor prohibit the use of fly baits or pest strips by untrained personnel. There is ample evidence that officials did not control fly baits and pest strips and that untrained personnel routinely handled both products. Veterans reported that fly baits were used in or around dining facilities,[27] and that personnel other than PM, field sanitation, and food service personnel placed fly baits in common areas (e.g., sleeping tents, work tents, etc.) to control the fly problem.[28] PM staff and field sanitation teams also applied fly bait in and around latrines.

Approximately seven percent of servicemembers in the Gulf were exposed to dichlorvos pest strips hung in various indoor locations to control flying insects.[29] The pest strip label recommended one strip per 1000 cubic feet, which equates to one strip per small general-purpose tent or two strips per medium general-purpose tent.

The military authorized untrained personnel to use the aerosol spray d-phenothrin for general use as an area spray and allotted each member of the Army field sanitation teams approximately one can of d-phenothrin.[30] Some personnel sprayed d-phenothrin in enclosed areas, such as tents, to kill flying insects. After DEET and permethrin repellents, d-phenothrin spray was the most requested insecticide from the military supply system in the Gulf.[31]

About 28% of servicemembers in the Gulf used d-phenothrin aerosol spray to control flies and mosquitoes inside tents and other structures.[32] The label advised the user to spray the area for no more than 10 seconds per 1,000 cubic feet, close the area for 30 minutes, and ventilate the area before personnel reentered. Individuals used this pesticide with little or no supervision.

3.  Personal Delousing Agent

RAND’s survey revealed that only about seven percent of US personnel used pesticides in powder form for personal use. Lindane was the only possible active ingredient in this form of pesticide.[33]

Army field sanitation teams were authorized an allowance of lindane of 192 two-ounce bottles per unit.[34] This was about one bottle per individual assigned to the average company of about 180 personnel. According to the Contingency Pest Management Pocket Guide, lindane was to be issued for treatment of clothing, but only when authorized by medical authorities.[35] The allowance of lindane for Army field sanitation teams may have made it likely that lindane was more readily available to Army personnel than it was to personnel of the other services.

Mass delousing of enemy prisoners of war should not be confused with personal delousing. Lindane use as a delousing agent for enemy prisoners of war is discussed in Section A.4.D,  Delousing Pesticide.

4.  Flea and Tick Collars

A significant number of veterans have reported using pet flea and tick collars to protect themselves against insects. These collars typically contain one of several active ingredients, in concentrations from five to twenty percent. The EPA-registered pesticides as the active ingredient in flea and tick collars available in the 1986-1991 timeframe were chlorpyrifos, diazinon, dichlorvos, and propoxur.[36]

Three percent of the RAND survey sample said they had used flea and tick collars to protect themselves against insects during the Gulf War deployment, and five percent of this group reported experiencing side effects.[37] Of 13,599 veterans interviewed by OSA investigators, 85 (0.625%) said they had personally used flea and tick collars or had witnessed others using them. While the majority of the veterans OSA interviewed indicated they had not experienced an adverse reaction, there were a few who experienced some form of skin irritation. Figure 6 is an example of the type of irritation that may have been experienced by some Gulf War veterans.

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Figure 6.  Result of misuse of flea and tick collars
Source:  Richard Fitzsimons, US Army Medical activity, Fort Leonard Wood, MO.

Several veterans reported that their command took positive actions to prohibit use of the collars. As early as the middle of September 1990, the Army’s Health Services Command released a message warning that prolonged exposure to the collars could produce toxic effects in humans. The chemicals in the collars could also compromise a wearer’s ability to recover from a nerve agent exposure.[38] The Health Services Command message encouraged soldiers to use military issued repellents and to properly wear the battle dress uniform to protect against biting flies, ticks, and fleas.[39] As late as February 1991, the Army’s Office of the Surgeon General issued news releases about why military personnel should not use the flea and tick collars.[40]

We have not included a health risk assessment for flea and tick collars in this interim report. Flea and tick collars were not included 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. Additionally, we had no information on which of the numerous active ingredients were present in the collars used by servicemembers. Because of the small surface area of skin covered by the collars, and the slow release of active ingredients, it is unlikely that consequential doses would be absorbed, despite the fact that local skin reactions occurred. Information recently received from the EPA may enable investigators to conduct a risk assessment of flea and tick collars in the future.


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