Figure 1 provides a simplified illustration of the pesticides investigation process conducted by the Deployment Health Support Directorate (DHSD). The DHSD investigation included a review of Gulf War records, documents, and related materials such as journal articles, and a review of DoD policies and guidelines involving the use and management of pesticides. Additionally, the investigation incorporated information from a RAND literature review of the health effects associated with pesticide exposure, and a RAND survey of 2,005 Gulf War veterans focusing on their use of and exposure to pesticides used during the Gulf War. DHSD interviewed over 900 other veterans to acquire information on pesticide application and management. Finally, DHSD synthesized all the information collected into the present Environmental Exposure Report, including a comprehensive health risk assessment (HRA). The HRA identifies and addresses in detail 15 pesticides of potential concern (POPCs), which posed the greatest potential for hazard to US servicemembers. Further details on the findings of the investigation are presented in Section IV.E.

B. Policy, Doctrine, and Guidance

The EPA regulates pesticide use within the US under the authority of two laws—the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and the Federal Food, Drug, and Cosmetic Act.^[20] FIFRA classifies pesticides as either restricted or general use.

DoD Directive 4150.7, "Department of Defense Pest Management Program," provided policy for DoD pest management and control operations worldwide for all services during the Gulf War. Modeled after EPA standards, DoD’s policy was to "establish and maintain safe, efficient, and environmentally sound integrated pest management programs to prevent or control pests that may adversely affect health or damage structures, material, or property." The directive specified overall pesticide use and control standards, including guidance for DoD operations in foreign countries and guidance for training requirements.

DoD policy required assessing possible adverse environmental or public health effects before applying pesticides. DoD policy also required individual military components to implement pesticide surveillance programs to protect the health and safety of personnel occupationally exposed to pesticides.^[21]

The Armed Forces Pest Management Board (AFPMB) Technical Information Memorandum Number 24, "Contingency Pest Management Pocket Guide" (the Pocket Guide), provided basic guidance for using pesticides in field situations worldwide by "preventive medicine/pest control personnel who have been formally trained and certified as Department of Defense Certified Applicators of Restricted Use Pesticides." The Pocket Guide warned other personnel not to procure or use pesticides or listed equipment unless service regulations specifically authorized them to do so.^[22]

The Pocket Guide’s information was intended to complement rather than substitute for the label instructions of specific EPA-approved pesticides. When using pesticides in areas outside the EPA’s jurisdiction, as was the case in the KTO, the host country’s accepted standards and procedures or the host-tenant agreement between the US and the foreign government applied. In the absence of host country standards or applicable agreements, federal guidance required PM personnel to follow EPA or the service’s requirements, whichever are more stringent. In short, the EPA-certified label was considered the law governing the proper use of individual pesticides. The Pocket Guide did not address the local purchase and use by non-PM personnel of pesticides that were not tested, approved, or labeled following EPA standards.^[23]

The Pocket Guide stated that if a person applying a pesticide (applicator) had only a substitute pesticide formulation available, the applicator’s superiors (or in their absence, the applicator) must decide whether to use the substitute. The Pocket Guide warned the applicator to be certain the benefits of killing the pests outweighed the risks to personnel.^[24]

The Pocket Guide specifically warned against relaxing safety requirements for the sake of quick-fix solutions and emphatically stated that PM personnel must meet all safety requirements listed on pesticide labels. In addition, the Pocket Guide issued a further caution to always use appropriate protective equipment.^[25]

While DoD Directive 4150.7 and the Pocket Guide contained the basic standards and policies governing all DoD components, including pest control programs, during the Gulf War, the individual services had manuals and regulations governing their own individual applicators and specialists. The directive established minimum levels of pest control for DoD installations and program policies for pest management implementation. DoD designed standards to meet or exceed those the EPA had established.

Under DoD domestic training and certification procedures, the training for pesticide applicators involved the completion of an AFPMB-approved correspondence course and formal in-residence training at a DoD training facility. The individual’s previous experience and training determined whether he or she required an apprenticeship.^[26]

DoD applicator certifications expired after three years. In the Navy, Environmental Health Officers, Preventive Medicine Technicians, and a small number of Navy Seabees were the certified personnel routinely assigned pest surveillance and control responsibilities. Shipboard pest control personnel received additional training. Army Preventive Medicine Specialists (MOS 91S) were trained in pest control operations. Army Field Sanitation Team (FST) training included 20 hours of training in all tasks, of which six to seven hours addressed insects, DoD and service pesticide control policies and procedures, and the performance of pest control functions. Certified Air Force Civil Engineering Technicians also served as pest control applicators.^[27]

National Guard and Reserve personnel who might have to apply pesticides were not required to be certified under the DoD plan if they applied pesticides for less than 25 percent of their active duty time and/or did not apply restricted-use pesticides while on active duty. However, unless the Reservist or Guard member held a valid DoD applicator’s certification, he or she could apply pesticides only under the direct supervision of a professional pest management specialist or military-certified pesticide applicator.^[28]

The medical surveillance programs for personnel engaged in pesticide operations differed somewhat by branch of service. The US Navy and Marine Corps required pest management personnel engaged in routine pesticide operations to undergo medical surveillance by the Navy Bureau of Medicine and the Navy Environmental Health Center. The primary purpose of this program was to protect personnel from overexposure^.[29] The Army required periodic job-related examinations for all personnel potentially exposed to health hazards.^[30] The Air Force ensured all pest management personnel were physically qualified to work with pesticides by requiring a comprehensive baseline occupational physical exam, preferably before any pesticide exposure.^[31]

C. Pesticides - Identification, Use, Exposures, and Potential Health Effects

1. Pesticides of Potential Concern

DHSD investigators identified 15 pesticides of potential concern (POPCs) based upon manner of use, prevalence of use, and toxicity. The POPCs contained 12 different active ingredients, and posed the greatest potential for hazard to US servicemembers of all pesticide products used during the Gulf War. Active ingredients are the chemical components that kill or repel the target pest. This report, especially the health risk assessment, concentrates attention on the POPCs.

US servicemembers reportedly used or had available for use at least 64 pesticides and related products to provide protection from pests. This total includes sprays, powders, baits, and flypaper. These pesticides and related products contained 37 active ingredients.

The active ingredients contained in the POPCs—classified as repellents, pyrethroids, organophosphates, carbamates, and organochlorines—are shown in Table 1. Pesticides are often identified according to their mode of action or by their chemical properties. Mode of action refers to the way in which a pesticide achieves its effect; for example, the manner in which it interferes with a biological process to cause the death of an insect. Repellents act to deter the presence of unwanted insects but do not necessarily act by killing the insect. The terms "organophosphate" and "organochlorine" are used to identify pesticides based on their general chemical compositions. Organophosphates are chemical compounds that contain carbon and phosphorous atoms in their chemical structure. Organochlorines are chemical compounds that are made up of carbon and chlorine atoms. Both means of identification will be used to describe the pesticide products cited in this report.

Pyrethroids include both natural and synthetic compounds that kill by attacking the nervous system of the insect. The aerosol spray products permethrin and d-phenothrin were the two pyrethroids of concern. According to the directions for use, permethrin was only to be applied to uniforms and such articles as tents, bedding, insect netting, and camouflage helmet covers, and allowed to dry prior to being used.^[32] Permethrin was applied to clothing because of its repellent properties, although it is also toxic to many pests at higher concentrations than those used. The product d-phenothrin was used in enclosed areas to kill flying insects.

DEET, permethrin, and d-phenothrin were available for application by all personnel. Special training or certification was not required to use these products. Training and/or certification were required by DoD policy to apply pesticides classified as organophosphates, carbamates, or organochlorines. An exception to this was the use of the organochlorine lindane by individuals on their own clothing (Section IV.C.2.b, "General Use Pesticides"). In addition, Army field sanitation teams (FSTs), which received only limited training, were authorized to use the organophosphate chlorpyrifos and the organochlorine lindane contained in their field sanitation kits. Further details on FSTs are presented in Section IV.C.2.c.(2).

There were five organophosphates among the POPCs. Azamethiphos was used primarily in the form of granular fly baits against fly populations. Azamethiphos was not, nor is it now, an EPA-approved pesticide and it has never been manufactured or distributed in the United States. Diazinon was sprayed in cracks and crevices, killing insects that came into contact with treated surfaces. Chlorpyrifos and malathion were used as sprays on surfaces (in a manner similar to diazinon) and for fogging populated areas. Resin strips impregnated with dichlorvos were hung in enclosed areas and emitted a vapor that killed insects.

The carbamates among the POPCs included bendiocarb, methomyl, and propoxur. Bendiocarb and propoxur were used very much like the organophosphate sprays mentioned above. Methomyl was a fly bait used in the same manner as the organophosphate, azamethiphos. The EPA has approved methomyl for use by the general public.

Lindane was the only organochlorine among the POPCs. Military police and PM personnel applied lindane to enemy prisoners of war (EPWs). To a very limited extent, some individuals used lindane on their own clothing.

2. Pesticide Use in the Gulf War

a. Introduction

During the Gulf War, US military PM resources controlled pest-borne diseases. Preventive medicine 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. Under conditions of inappropriate application, exposures may have occurred that 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, investigators from the Deployment Health Support Directorate (DHSD) conducted over 900 interviews with veterans we believed might have information about pesticide use during the Gulf War, including preventive medicine personnel. Of these interviews, 322 provided specific information related to pesticide exposure (e.g., frequency with which a pesticide was applied, application rates, personal protective equipment worn, etc.).

The RAND survey of Gulf War veterans, described in Section IV.E.4, provides the best available information on the patterns of pesticide use by the general military population. Such pesticides included those for personal use, and those applied in or around living or working areas.

Investigators have not, however, been able to determine the amounts of each pesticide used during the Gulf War. They were only able to find material ordering data, not actual usage data (e.g., application rates).

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.

The following three subsections report on the use and application of three categories of pesticides by US personnel during the Gulf War: general use pesticides, field use pesticides, and delousing pesticide. This information serves as the basis for determining pesticide exposure levels that subsequently will be used in the HRA to evaluate the potential for health effects. Table 2 presents a use and application overview for the POPCs. Note that the percentage of active ingredient in each pesticide product is listed in the table. For example, DEET 33% cream/stick means that 33% of the pesticide product is the active ingredient DEET.

b. General Use Pesticides

General use pesticides are 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. Additionally, veterans and official documentation indicate some personnel wore pet flea and tick collars, which were neither designed nor authorized for personal use. 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. The United States Central Command (USCENTCOM) and each component service generated guidance dealing with the need for protective measures against the pest threat. The USCENTCOM surgeon’s office provided much of the initial PM guidance for units deploying to Operations Desert Shield/Desert Storm.

Table 2. POPCs use and application overview

(1) Repellents

USCENTCOM emphasized the "DoD Repellent System," a properly treated and worn uniform plus the use of repellents (Figure 2).^[33] Proper wear meant the pant legs were tucked into the boots, the sleeves were rolled down, and the collar was buttoned. Each service issued similar guidance. The DoD Repellent System was poorly implemented due to shortages of repellents, lack of information about the system, and varying levels of compliance with the guidance by individuals or units.

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.^[34] This conflicted with guidance on the permethrin label, which instructed the user to "reapply after six weeks and sixth laundering."^[35]

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.^[36] 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.^[37] 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^.[38]

DEET has been used by US forces and civilians worldwide since the mid-1950s as an all-purpose repellent applied to skin and clothing. EPA has registered over 200 commercial DEET products. Commercially-available DEET products, designed for skin application, vary from 4 to 100 percent active ingredients.^[39]

About 44% of servicemembers in the Gulf used permethrin spray—mainly on battle dress uniforms (BDUs), tents and mosquito nets.^[40] Normally, servicemembers waited two to four hours for the permethrin spray to dry before wearing the uniform.

Even when supplies were available, soldiers did not always comply with the guidance on DEET and permethrin.^[41] Some individuals have indicated that the odor of one or both repellents was offensive, which may have resulted in decreased use.^[42]

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 FSTs approximately one can of d-phenothrin.^[43] Some personnel sprayed d-phenothrin in enclosed areas 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.^[44]

According to the RAND survey, approximately 28% of servicemembers in the Gulf used d-phenothrin aerosol spray to control flies and mosquitoes inside tents and other structures.^[45] 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.

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 products are one percent methomyl and one percent azamethiphos, respectively.

The military supply system supplied Stimukil and other fly baits containing methomyl. They were also purchased locally. Azamethiphos-based products (e.g., Snip�) were purchased locally.

When a fly consumed the granules, the active ingredient acted on the fly’s central nervous system, resulting in death. These pesticides were authorized for outdoor use only; however, veterans indicated that fly baits may have been used in any of the areas where personnel worked, ate, and slept, often placed in open containers inside or outside buildings and tents, and even spread on the ground. Trained or untrained personnel and field sanitation teams applied baits. According to the RAND survey, approximately 12% of servicemembers in the Gulf applied or were exposed to fly baits. PM personnel interviews showed that the Army used azamethiphos -based baits as often as those containing methomyl.^[46] The Marine Corps and the Navy used methomyl-based fly baits more than twice as often as those containing azamethiphos. The Air Force apparently used methomyl-based baits almost exclusively. Exposures occurred both when the bait was applied and when servicemembers were in the vicinity of the applied baits.

The military did not specifically authorize nor prohibit the use of fly baits by untrained personnel. There is ample evidence that officials did not control fly baits and that untrained personnel routinely handled the product. Veterans reported fly bait use in or around dining facilities, ^[47] and personnel other than PM, field sanitation, and food service personnel placing it in common areas to control the fly problem.^[48] PM staff and FSTs also applied baits in and around latrines.

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

According to the RAND survey, approximately seven percent of servicemembers in the Gulf were exposed to dichlorvos pest strips hung in various indoor locations to control flying insects.^[49] The pest strip label recommended one strip per 1,000 cubic feet, which equates to one strip per small general-purpose tent or two strips per medium general-purpose tent.

The military did not specifically authorize nor prohibit the use of pest strips by untrained personnel. There is ample evidence that officials did not control pest strips and that untrained personnel routinely handled the products.

Army field sanitation teams were authorized an allowance of lindane of 192 two-ounce bottles per unit.^[50] 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.^[51] The allowance of lindane for Army FSTs may have made it likely that lindane was more readily available to Army personnel than it was to personnel of the other services. The RAND 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.^[52] Mass delousing of enemy prisoners of war (EPWs) should not be confused with personal delousing. Lindane use as a delousing agent for EPWs is discussed later in this section and in Tab H.

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 active ingredients contained in EPA-registered flea and tick collars available in the 1986-1991 time frame include chlorpyrifos, diazinon, dichlorvos, and propoxur.^[53]

Three percent of a telephone 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.^[54] While the majority of the veterans surveyed 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.

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 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.^[55] 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.^[56] 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.^[57]

(c) Field Use Pesticides

In addition to repellents, fly baits, pest strips, and area sprays, the general military population was exposed to pesticides applied in the field by professionally certified and trained applicators and field sanitation teams. Professional applicators applied pesticides as sprayed liquids, sprayed powders, or fogging pesticides. Each is discussed below.

• Sprayed liquids - Liquid pesticides (commonly known as emulsifiable concentrates or ECs) were sprayed on the outside base of walls or tents, the outside of garbage containers, and other places where pests congregated. They were 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. Army applicators primarily used chlorpyrifos and diazinon. Navy and Marine applicators primarily used chlorpyrifos and malathion, while the Air Force frequently used diazinon. All the services also used propoxur and malathion to a lesser extent.
  
  
• Sprayed powder - Bendiocarb powder was mixed with water (known as a wettable powder, or WP) 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 around 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.
  
  
• Fogging pesticides - Pesticide products containing chlorpyrifos and malathion were applied outdoors as a fog to control filth flies, sand flies, and mosquitoes. Truck-mounted and backpack sprayers discharged the fog outside living quarters, mess tents, and latrines. The Navy/Marine Corps and the Air Force primarily used fogs.

The Army, Navy, and Air Force each had certified pesticide applicators. Army (specialty code 91S) and Navy (specialty code HM8432) applicators came from the PM community and performed other PM functions in addition to pesticide application. Air Force pest controllers (specialty code 566X0) came from the civil engineering community. All three services’ applicators went through similar training and certification processes.

The applicators’ experience varied largely by service. Because Air Force pest controllers were in an occupational specialty dedicated to pest control, they had the most actual application experience. For most Army and Navy PM personnel, participation in pest management operations only occurred during deployments or field training. Navy PM technicians who previously served aboard ship or with a Fleet Marine unit generally had more pesticide application experience than Army PM personnel, due to shipboard duties or pest control requirements during deployments.

Certified applicators applied fly baits and pest strips, sprayed liquids and powders, and conducted area fogging. The pesticide sprays required mixing (usually with water) and were applied in various locations around camps. Sprayed liquids usually contained one of four active ingredients: chlorpyrifos, diazinon, malathion, or propoxur. The applicators sprayed a fifth chemical, bendiocarb, a powder that is also mixed with water. Applicators applied fogging pesticides using truck-mounted sprayers and motorized backpack foggers.^[58]

Among the services, only the Army employed field sanitation teams (FSTs). FSTs provided small Army units with limited PM resources to reduce the incidence of disease and nonbattle injury (DNBI). FSTs also assured that Army units established and maintained appropriate field sanitation facilities. A team, by doctrine, consisted of at least two soldiers, one of which was a noncommissioned officer. When available, combat medics were a part of the team.^[59] PM personnel occasionally visited and monitored the FSTs, but were not often present when the teams applied pesticides.

The military trained FSTs in food service sanitation, field waste disposal, heat and cold injuries, and pest management. The recommended seven-hour pest management course for team members covered such topics as insects and disease, environmental and chemical control of insects (including 2 hours on pesticides and pesticide application equipment), and rodent control.^[60] Some teams received training before leaving the United States, but because some units did not designate teams until after arrival in theater, the Army instituted in-theater FST training,^[61] which was frequently abbreviated^.[62]

The only pesticides the Army authorized FSTs to use were chlorpyrifos and lindane. Chlorpyrifos was mixed and applied in a two-gallon sprayer (Figure 7).

(d) Pesticide Use During EPW Delousing Operations

Coalition forces captured 86,743 enemy prisoners of war (EPWs) during Desert Storm. US-operated EPW facilities processed 69,822 prisoners. The Army’s 800^th Military Police Brigade was responsible for the EPWs and operated four camps; each was charged with escorting, processing, and interning EPWs in a safe and secure environment.^[63]

Given the large numbers of EPWs, US authorities were concerned about an outbreak of typhus, a disease transmitted by lice and known to occur in crowded human populations where personal hygiene conditions are poor. US forces selected lindane powder (one percent) for delousing.^[64]

The delousing procedure specified applying one or two ounces of lindane powder to clothed individuals, ^[65] spraying beneath the clothing at the neck, sleeves, and waist; then whitening the head and hair with dust, and dusting the inside of the hat. The military police used two types of delousing equipment: the first, a plunger-type hand delouser with a six-inch extension tube, could treat approximately ten individuals before running out of lindane (Figure 8); the second, a gasoline-powered delouser, ideally, could treat up to six hundred personnel per hour (see Figure 9). However, equipment malfunctions diminished the actual processing rate.

Lindane application procedures varied among camps. The instructions on the lindane label advised that a respirator and eye protection should be worn during delousing operations, and that lindane should be used only in open or well-ventilated areas.^[66] Because lindane is a powder, applicators could be exposed through skin contact and inhalation. Generally, PM personnel and military police personnel served as applicators, working shifts as long as twelve hours in around-the-clock delousing operations^.[67] Based on information received during veterans’ interviews, on at least two occasions, EPWs or military police applied lindane using their bare hands because power equipment or plunger-type delousers were unavailable.^[68] In three of the four camps, delousing operations generally took place inside a tent.^[69]

The availability of personal protective equipment (PPE) for applicators varied. Well-protected delousing personnel wore respirators and rubber or plastic gloves.^[70] Some veterans reported that only mission oriented protective posture (MOPP) gear - designed for chemical and biological warfare - was available.^[71] Other delousing personnel wore little or no PPE.

Investigators estimate that 40 to 50 individuals at each camp were directly involved with delousing and would have experienced the greatest exposure to lindane. Investigators interviewed a total of 60 personnel, 40 of whom had been actively involved in delousing activities, while the others simply witnessed the process.

(e) Pesticide Use by British and French Forces

Investigators obtained information about pesticides used by troops from the United Kingdom and France. The British military supply system stocked malathion dust for delousing, bioallethrin for fogging, and fenitrothion, propoxur, and bendiocarb as residual pesticides. Residual pesticides remain active in or on a treated location for long time periods. The British also supplied their military personnel with DEET for skin application and permethrin for clothing and mosquito netting. The British used permethrin as an area spray, similar to US use of d-phenothrin. British PM personnel initiated local purchases of azamethiphos-based pesticides for fly control after observing the effectiveness of the products (see Tab G for information on fly baits).^[72]

During the Gulf War deployment, French servicemembers applied K-orthrin (active ingredient deltamethrin) to mosquito netting, pyrethrins for pest control on aircraft, and lindane (in both powder and solution forms) for laying on the ground and spraying on tent walls and building walls. In addition, French servicemembers applied insect repellents containing DEET.^[73]

(f) Pesticide Use by Host Nation Applicators

During the Gulf War, host nation support often included pest control services that were part of existing contracts with facilities leased by US forces, or in the case of Saudi Arabia, by the public health departments of Saudi municipalities. In some instances, deployed US forces contracted with local pest control services. The US used these services primarily in more established camps and leased compounds. Pest control services tended to be available in or near urban areas, but were not prevalent in the temporary desert camps. These outlying camps generally used US military pesticide applicators.

Only limited data and information were available on the pesticides used by host nations, their training and certification requirements, and their application methods. Consequently, this section is based primarily on information from interviews with US PM personnel. Preventive medicine personnel provided most of the information that served as the basis for inclusion of pesticides in the group that was investigated. Due to incomplete information on the precise specifications and the frequency of use, investigators did not include host nation pesticides in the health risk assessment (Tab D). However, the HRA does include pesticides with similar or the same active ingredients as those used by host nations.

There were several observations recorded concerning host nation pesticide use. An Air Force environmental health technician, who served at an air base in Tabuk, Saudi Arabia, obtained a list of pesticides used by contractors hired to apply pesticides at the base. He reported that contractors mixed the pesticides incorrectly, producing higher than recommended concentrations of the active ingredient. He also learned that the contractors’ pesticide selections depended on what was available.^[74] Three interviewees reported that pest control personnel in Bahrain used DDT, which was available for purchase there.^[75]

Some PM personnel expressed skepticism about some host nation procedures, including the training, knowledge, and experience of their applicators.^[76] Some Air Force pest controllers in Saudi Arabia and the United Arab Emirates felt that the applicators they observed were inadequately trained.^[77] An 82^nd Airborne Division PM specialist said that PM personnel at one facility stopped pesticide applications because the applicators did not know what product they were using.^[78] A Navy entomologist thought that host nation applicators observed less-stringent standards than US applicators.^[79] One Navy environmental health officer reported applicators applied pesticides despite high wind conditions, and another questioned the standards to which host nation applicators adhered.^[80]

Many interviewees commented favorably on host nation pesticide activities. An Air Force pest controller assigned to a United Arab Emirates air base felt the applicators he observed appeared to follow standard application procedures.^[81] An Army entomologist commented that local pest control contractors were well trained.^[82] Two Navy entomologists who served with the Marines in the Al Jubayl area visited a pest control shop that conducted fogging operations for the Navy facilities. The shop used cypermethrin and deltamethrin in fogging operations.^[83] The senior Navy entomologist considered both of these products safe if applied as directed.^[84] The Navy entomologist found that a trained entomologist ran it, and that it was well-equipped and used safe pesticide products.^[85]

Except for the concerns mentioned by the Air Force environmental health technician, the interviewees did not express reservations about the specific active ingredients. The identified host nation pesticides contain active ingredients that are registered in the US. Table 3 lists some of the pesticides used by host nation pest control services. It reflects only the information collected at two locations and therefore should not be considered a comprehensive list.

Except for diazinon, malathion, and permethrin, the host-nation-applied-pesticides in Table 3 were not included in this investigation. The known uses in the US for cypermethrin and pirimiphos-methyl are exclusively agricultural in nature.^[86] Deltamethrin has household, agricultural, and public health uses in the US.^[87] Warfarin and other rodenticides do not present a hazard to humans through dermal contact or inhalation under normal circumstances. Ingestion is the only route by which these products normally pose a risk to humans, and this would require an extremely unlikely misuse. Temephos is an organophosphate that is supplied in various forms. Its toxicity is comparable to that of chlorpyrifos and malathion.

Table 3. Pesticides used and stocked at two host nation facilities

3. General Aspects of Pesticide Exposure

Exposure is the contact of a chemical such as a pesticide with the skin, lining of the digestive system, or the lining of the airways. For the pesticides used in the Gulf, exposures may have occurred in a variety of ways, despite the numerous precautions required. For example, perhaps one-fifth of the DEET applied would have been absorbed through the skin, while little or none would have been ingested (swallowed) and inhaled. A small fraction of the permethrin sprayed on clothing, tents, insect netting and helmet covers may have been absorbed through the skin and inhaled, while little or none would have been ingested. Pesticide fogging around living quarters also may have contributed to a significant level of pesticide inhalation. Servicemembers in the immediate vicinity of pest strips would have been exposed to pesticides via inhalation, and pesticides may have been absorbed through the skin and inhaled due to the unauthorized use of pet flea and tick collars.

A pesticide discharged as a spray directly into the air may be inhaled, ingested, 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.

The consequences of exposure to pesticides depend on a number of factors, including: the level, duration, and frequency of each 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.

4. Potential Health Effects

As part of this effort to evaluate the possible health effects of pesticides on Gulf War veterans, the Deployment Health Support Directorate commissioned RAND to review the existing scientific literature on the health effects of the active ingredients in the POPCs used during the Gulf War deployment. The objective was to gain a better understanding of the possible causes of undiagnosed symptoms reported by veterans.^[90] The report summarizes the relevant literature and includes reports of known pesticide exposures and doses and the related health outcomes. RAND investigators combined this review with information from the EPA and other sources to produce a health effects analysis.

Although all pesticides can be toxic to humans in large doses, the pesticides sent to the Gulf were typical of products readily available in the US at the time and were considered safe for general unrestricted use within the US. The pesticides of potential concern (POPCs) are categorized below by group or class. These groups include organophosphates, carbamates, organochlorines, pyrethroids, and repellents (DEET). This section provides an overview of potential health effects for the POPCs reportedly used during the Gulf War deployment.

a. Organophosphates

Organophosphates used during the Gulf War deployment include azamethiphos, chlorpyrifos, diazinon, dichlorvos, and malathion. Examples of organophosphate products used include Snip^� fly bait, Dursban^�, and pest strips. Organophosphate pesticides, like carbamate pesticides, act by binding to and inhibiting the action of the enzyme acetylcholinesterase (AChE), which is found in both blood and the nervous system. AChE in the nervous system serves a critical role in regulating impulses between nerves, and between nerves and muscles. The body can withstand some inhibition of AChE with no ill effects.

Exposure to large amounts of organophosphorus pesticides can cause nerve and muscle disorders. Acute symptoms span a range from mild to severe depending upon the degree of AChE inhibition. Mild symptoms include narrowing of the pupil and runny nose; more severe symptoms include additionally any or all of the following: dizziness, nausea, vomiting, rapid heart rate, breathing difficulty, and death. Acute symptoms of organophosphate poisoning usually appear within a few hours of exposure. Generally, reports of pesticide intoxication are associated with accidental exposures or mishandling/misapplication of pesticides.

Organophosphate Induced Delayed Neurotoxicity (OPIDN) or Organophosphate Induced Delayed Polyneurotoxicity (OPIDP) is a form of delayed clinical and pathological response to organophosphates requiring significant acute exposure. Studies show weak experimental evidence of associations between chlorpyrifos and OPIDN and between dichlorvos and OPIDN, but not for the other POPC organophosphates.

Some reports indicate that symptomatic exposures to organophosphates (e.g., runny nose, temporary cough, and burning eyes near the time of exposure) may result in lingering effects months or years later. One to several years after exposure, persistent symptoms may include fatigue, headache, joint and muscle pain, memory problems, upper and lower respiratory problems, gastrointestinal disturbance, dizziness, atrophy, and antibiotic sensitivity.^[91]

The literature suggests that exposures to organophosphate pesticide levels that cause acute health effects at the time of exposure and require medical attention are associated with elevated rates of neurological or psychiatric symptoms and poorer performance on standardized neuropsychological tests several years after the exposure.^[92] Most studies of low-level occupational exposures suggest that these and other long-term effects occur solely in the aftermath of severe and immediate organophosphate pesticide poisoning.^[93] In contrast, RAND cites evidence that modest long-term effects may occur following exposures that were insufficient to lead to acute symptoms.^[94]

b. Carbamates

Carbamates used during the Gulf War included bendiocarb, methomyl, and propoxur. Examples of carbamate products used include Apache^� fly bait, Baygon^�, and Ficam^�. Like organophosphates, carbamates act by inhibiting AChE and can cause similar immediate poisoning effects. Poisoning with carbamates tends to be of much shorter duration compared with organophosphorus pesticides. While many organophosphates may irreversibly inhibit AChE, the effects of carbamates on AChE enzyme are always reversible.

The acute symptoms of carbamate exposure are similar to those described for organophosphates. Chronic symptoms resulting from exposure to AChE inhibitors may include fatigue, joint and muscle symptoms, sleep effects, headaches, skin effects, cognitive effects, mood effects, and neurological effects.^[95] As with organophosphate pesticide poisoning, most studies suggest that long-term effects can occur solely in the aftermath of severe and immediate poisoning.^[96] Once again, however, RAND cites evidence that modest long-term effects may occur following exposures that were insufficient to lead to acute symptoms.^[97]

c. Organochlorines

The military reported that lindane was the only organochlorine pesticide obtained from the US supply system for delousing during the Gulf War. Lindane has been widely used for about 50 years as an insecticide on crops and in medicinal formulas to treat head lice and scabies (e.g., Kwell^� shampoo), so there exists a fair amount of data on its efficacy, safety, and toxicity.^[98]

Lindane also affects the nervous system, but in a manner different from organophosphates and carbamates. Extreme lindane overexposure may result in convulsions. The main routes of exposure include dermal contact, ingestion, and inhalation. Mild symptoms of exposure following dermal contact include headache and nausea. The EPA asserts that there is only suggestive evidence that lindane may cause cancer in humans based on an increase in benign tumors in female mice only.^[99] This is fairly weak evidence of cancer-causing potential. Although, it is no longer recommended as the first-line drug treatment for scabies and body lice, it is generally considered safe and effective when used appropriately.^[100]

The RAND literature review notes that acute symptoms in humans exposed to lindane include headache, nausea, vomiting, restlessness, loss of muscular coordination, tremor, excitability, and coma. Seizure has been reported with more extensive exposures, although specific levels at the time of exposure are not available.^[101] Many of these symptoms are reversible with supportive care. However, deaths have been reported following lindane ingestion.^[102]

The RAND report also notes that few studies in the literature describe the effects of chronic dermal exposure because lindane treatments generally require only one application. Further, epidemiologic studies suggest the possibility of subtle long-term neurological and reproductive health effects; however, subjects in these studies were exposed to a number of different potentially toxic substances, making it difficult to attribute findings specifically to lindane.^[103]

d. Pyrethroids

Pyrethroids used during the Gulf War included permethrin and d-phenothrin. An example of a pyrethroid used is Airosol^�. In general, pyrethroids are considered safe and effective when used as recommended; however, they are potentially toxic at extremely high exposures. Even when used properly, minor skin irritation in sensitive individuals may result.^[104]

The literature contains a limited number of references for acute symptoms from permethrin exposure. With occupational exposure, individuals experienced facial skin sensations (burning or itching) within a few hours of exposure. With ingestion, digestive symptoms included stomach pain, nausea, and vomiting. Acute poisoning symptoms include dizziness, headache, nausea, loss of appetite, and fatigue. Symptoms are reversible and subside with discontinuance of exposure.^[105]

RAND notes that the literature cites very few references for d-phenothrin, and those that are cited repeatedly address the relative safety of this insecticide, and of pyrethroids in general.^[106]

e. Repellents

Based on available data, EPA has concluded that DEET is of low acute toxicity and normal, intermittent use for days or weeks does not present a health concern to the general population. It is the active ingredient still used in many common over-the-counter repellent products, including sprays and lotions. During the recent EPA review of DEET, the agency considered exposures to be brief, and long-term exposure was not expected. DEET has been classified as an EPA Group D carcinogen (i.e., not classifiable as to human carcinogenicity). Mutagenicity tests have been negative. With the exception of infrequent incidents of scarring, there have been no long-term effects from chronic exposure to DEET.^[107]

Most of the health effects reportedly caused by DEET are acute. DEET has been associated with a number of symptoms that may affect cardiovascular, dermatologic/allergic, and nervous systems. Reports of severe effects from DEET describe nerve pain, mainly in children. Severe DEET toxicity may result in encephalopathies in children.^[108]

Reviews of DEET toxicity generally indicate that the risk of adverse effects from using repellents as directed is low. Concerns have been raised regarding the interaction of DEET with other chemicals, such as pyridostigmine bromide (PB) and permethrin. However the available literature is incomplete.^[109]

f. Inert Ingredients

Pesticides contain active ingredients and inert ingredients. An active ingredient is the specific chemical in a pesticide responsible for repelling or killing the pest. For example, "DEET, 33 percent cream" means that 33 percent of the pesticide product is the active ingredient DEET and that other substances make up 67 percent of the product. Some of these other substances are added to make application easier. Inert ingredients are other components in the product that are not intended to affect pests but are used to help formulate, stabilize, or disperse the product. The designation "inert," as used by EPA, means that the chemical does not have recognized pesticidal activity, and is not regulated by EPA as a pesticide. Current laws and regulations do not require that inert ingredients be identified by name on the label.

EPA has categorized over 1,600 inert ingredients found in registered pesticides into four groups. These groups include inerts of toxicological concern, inerts of potential toxicity with high priority for testing, inerts of unknown toxicity, and inerts of minimal concern.

According to EPA, most inert ingredients do not pose health or environmental concerns; however, some inert ingredients may be more toxic or pose greater risks to human health and the environment than the active ingredients.^[110] The RAND literature review states that many of the inert ingredients in pesticide products may pose a hazard to human health and/or combine with active ingredients to produce an effect different from that predicted when using animal models.^[111] However, the potential hazards referred to were most likely determined in laboratory animal experiments and may not be relevant to veterans under real-world conditions.

Due to the limited information available on the inert ingredients used during the Gulf War, this investigation has focused primarily on the potential health effects of the active ingredients. In most cases, the military-issued pesticides used during the Gulf War were mixed with water as an inert carrier. However, inert ingredients frequently include petroleum products and solvents. Investigators have been unable to obtain reliable information on the inert ingredients used by host nation contractors.

EPA has formed an Inert Disclosure Stakeholder Workgroup to provide advice on how to make information on inert ingredients more available to the public. As a result, additional detail on inert or other ingredients may be available in the future.

g. Potential Interactions with Pyridostigmine Bromide (PB)

In 1999, RAND prepared a literature review on pyridostigmine bromide (PB) use during the Gulf War. PB tablets were taken orally to reduce the chance of death in the event of a nerve agent (soman) attack. Some researchers have suggested that, because PB is also an AChE inhibitor, interactions among PB, pesticides, and repellents may contribute to undiagnosed illnesses in Gulf War veterans.

Because of concerns about possible interactions between pesticides and PB, the RAND survey of pesticide use during the Gulf War collected data on PB use by veterans. The survey estimates that 223,501 servicemembers took PB.^[112] According to a retrospective study described in the RAND PB report, up to 50 percent of servicemembers taking PB had side effects, but fewer than one percent perceived a need for medical attention.^[113]

The RAND report on PB notes that animal studies found that the toxicity of PB is enhanced with simultaneous exposures to pesticides, insect repellents, caffeine, and stress. But, the degree to which these interactions between PB and other factors may play a role in Gulf War veterans is unclear. First, data on individual exposures is not available, thereby complicating the interpretation of epidemiologic studies. Second, some of the animal studies employed extremely high doses—doses much higher than those experienced by Gulf War veterans.

The RAND PB report concludes, however, that because evidence of synergistic toxicity exists - from animal studies using high doses and different routes of administration from those experienced by Gulf War veterans - interactions between PB and other agents cannot be ruled out as a source of toxicity in some veterans.^[114]

In contrast to the animal studies discussed above, a 2002 study by Abdel-Rahman, Shetty, and Abou-Donia may have potential relevance to veterans. This study investigated the effects of a combined exposure to moderate stress and low doses of PB, DEET, and permethrin in adult male rats. The authors concluded that the combination of stress, PB, DEET, and permethrin leads to significant brain injury, and that the various neurological symptoms reported by Gulf War veterans could be linked to this kind of injury.^[115] The exposure conditions used in this study appeared to be a fairly realistic approximation of veteran exposure using experimental animals. While the study demonstrates that brain injury may occur in animals under the experimental conditions used, it does not prove that such injury did occur in veterans.

It is important to note that the highest levels of pesticide use would probably not have occurred simultaneously with the highest levels of PB use. The highest levels of pesticide use, in general, would have been during warm months when the main pest populations were highest; that is, roughly August through November 1990, and March through June 1991. The RAND survey results indicate that servicemembers were more likely to take PB during January and February 1991 as a defense against chemical warfare attack than at other times, although servicemembers reported using PB as early as August 1990 and as late as July 1991.^[116] Exposure to pesticides weeks before exposure to PB would be unlikely to produce an adverse interaction. Similarly, exposure to PB at least several days prior to pesticide exposure would be unlikely to produce an adverse interaction.

h. Additional Epidemiologic Studies

The RAND literature review summarizes and evaluates information from numerous epidemiologic studies addressing pesticide exposure and chronic health effects in non-military populations. While these studies are relevant to Gulf War veterans, other studies are now available which should be considered. Four additional recent epidemiologic studies, not described in the RAND report, attempt to evaluate various aspects of the relationship between pesticide exposure and self-reported symptoms in Gulf War veterans from three different countries. A 1998 study of 341 US veterans found exposures to pesticides were significantly related to increased reporting of musculoskeletal and neurological symptoms.^[117] One 2001 study of 7,971 UK veterans found consistent, specific, and credible relationships between symptoms and the number of days spent handling pesticides. The symptoms reported were neurological or consistent with toxic neuropathy.^[118] A second 2001 study of 8,195 UK veterans found that multiple chemical sensitivity (MCS) was strongly associated with exposure to pesticides, and suggested that MCS accounts for some of the medically unexplained illnesses^.[119] A 1999 study of 943 Danish veterans found long-term gastrointestinal problems were significantly associated with insecticide exposure.^[120]

i. Case Reports of Signs and Symptoms

(1) Acute Symptomatic Exposures

DHSD investigators interviewed over 40 Gulf War veterans who described cases of possible symptomatic pesticide exposure in themselves or others (see Tab F, "Exposure Incidents Related by Preventive Medicine Personnel"). These reports vary substantially in the level of detail provided, and the intensity of the signs and symptoms described, and we could only corroborate one of them with a specific medical record generated during deployment. Two of the reports appear particularly credible, and are described below.

Case No. 1 describes an incident where a servicemember inhaled fumes from leaking containers of an unspecified insecticide at an air base in the KTO, and subsequently experienced burning in his lungs, nausea, stomach cramps, and dizziness. The servicemember, treated with intravenous fluids and oxygen and observed overnight, returned to duty the following day. A follow-up interview indicated that the veteran is currently not suffering from any health symptoms associated with the exposure incident.^[121]

Case No. 2 describes the serious symptomatic exposure of a servicemember assigned to an evacuation hospital. The exposure occurred while the servicemember, not using PPE, was preparing to apply a product described as a fly bait powder. During preparation, the powder came up in a cloud, was inhaled and ingested, and covered the servicemember’s face. The servicemember had a nosebleed within 30 to 45 minutes, chills within 8 hours, and chest pains, shortness of breath, and was admitted to an evacuation hospital as a case of toxic exposure within 10 hours after exposure. A chest X-ray showed a coin-sized spot on the upper portion of the left lung. The servicemember experienced fever and chills, excruciating chest pain, coughed up blood, and had consolidated lungs for about 10 days after being admitted. Investigators conclude that the product was most likely Alfacron 10^� wettable powder, which is 10% azamethiphos.

The veteran in Case No. 2 reports distinct memory and other cognitive problems since returning from the KTO. The veteran could not recall previous family activities and events, several routine occupational skills, and the names of co-workers. The veteran participated in a pilot program for people who had unusual exposures, underwent a Gulf War physical in 1995, and applied for disability in 1998. The veteran reports being diagnosed with cognitive dysfunction and progressive muscle weakness like multiple sclerosis, and attributes health problems to service in the Gulf.^[122]

The Deployment Health Support Directorate has completed a comprehensive automated search of the diagnoses contained in approximately 28,000 Gulf War veteran in-patient records maintained at the National Personnel Records Center. We conducted this search using a list of specific codes and key words intended to identify those records that might contain information on pesticide exposures. This search detected one diagnosis referencing pesticide exposure. This finding supports the contention that acute illness due to pesticide exposure was not widespread.

(2) Chronic Illness

One service-connected claim involving exposure to lindane was submitted to the Department of Veterans Affairs (VA) Board of Veterans Appeals. The surviving spouse of a veteran contended that her husband was exposed to various toxic chemicals, particularly lindane, during the Gulf War, and that as a result of exposure to lindane, the veteran was found three years later to have developed pancreatic cancer from which he subsequently died. The initial claim was denied but was awarded on appeal.

In the appeal, the Board considered scientific opinions presented on behalf of the appellant and by the VA. The scientific opinion on behalf of the appellant maintained that lindane likely caused the veteran’s cancer, while the VA did not recognize an association between lindane exposure in the Gulf and the veteran’s cancer. The Board concluded that the preponderance of the evidence presented favored the appellant’s claim. The Board found that it was "reasonably probable" that the veteran’s pancreatic cancer, which caused his death, resulted from his exposure to lindane during the Gulf War. Therefore, the Board granted service connection for the cause of the veteran’s death.^[123]

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