A.3  BACKGROUND

Preventive medicine (PM) assets focused on protecting the health of servicemembers during the Gulf War, including providing pest control. Insects (mosquitoes, flies, fleas, ticks) and rodents often carry diseases. Avoiding or controlling these pests interrupts the transmission of these diseases. Typically PM personnel first determine the pest threat in an area of operations and then implement physical control measures, such as careful selection of locations for units and facilities, and application of repellents and pesticides.[5] Since many diseases thrive in the harsh, unsanitary conditions found in war, failure to practice satisfactory field PM allows unnecessary disease and injury to occur. PM measures need vigorous command emphasis to succeed, and must be implemented at the beginning of any deployment to minimize casualties due to what the military calls disease and nonbattle injury (DNBI).[6] However, PM and pest control personnel must strike a balance between eliminating pests and exposing US servicemembers to levels of pesticides that may result in adverse health effects.

A.  Potential Pest-Borne Health Threats in the Gulf

Historically, campaigns fought in the Middle East have been accompanied by diseases (particularly dysentery and malaria) that played a disproportionate role in determining the outcomes. As recently as World War II, disease and health problems ravaged fighting forces deployed to the region on a par with hostile action.[7] Because sand fly fever was widespread in Iran and Iraq during World War II, US health officials viewed it as one of the most serious infectious disease threats. Important steps in minimizing pest problems included implementing proper sanitary controls and using pesticides appropriately.

Approximately 697,000 US servicemembers served in the KTO during the Gulf War. During this massive deployment, the Pentagon was concerned that infectious diseases would threaten servicemembers’ health. Following the war, however, medical reports identified only 40 cases of infectious diseases, including 32 cases of leishmaniasis, 7 of malaria, and 1 of West Nile fever. Contrary to what was expected by force health protection specialists, there were no documented cases of sand fly fever.

This low incidence of infectious disease among servicemembers was attributed to a combination of factors, including establishing a comprehensive infrastructure of medical care and PM. The PM resources controlled disease-bearing hosts, primarily insects and rodents, through proper sanitation procedures and pesticide use. Several fortuitous factors reduced the incidence of infectious diseases, including the cooler winter conditions at the height of the KTO buildup and the very nature of the barren desert where most US units deployed.[8] Without the more favorable conditions, the incidence of vector-borne diseases might have been greater. It also may have been necessary to put a greater emphasis on application of pesticides to suppress insect populations. Section A.4, Pesticide Use and Exposure, contains more information on the use, application and exposure to pesticide products, and Tab C-4, discusses pesticide-related PM efforts.

B.  Concerns About Pesticide Use in the Gulf

Preventive medicine personnel and those they supervised applied pesticides throughout the theater of operations during the Gulf War. Some pesticides, particularly the two groups known as organophosphates and carbamates, exhibit some similarities to certain chemical warfare agents (CWAs). Specifically, at high enough doses, the "V-series" and "G-series" nerve agent CWAs, and organophosphate and carbamate pesticides all cause toxicity by affecting the same sites in the nervous system. An important difference, however, is that the nerve agents are far more toxic than any of the pesticides approved for use during the deployment. Because of the similarities noted, and the potential for misusing or misapplying pesticides, veterans, veterans’ groups, researchers, government agencies, and foreign governments have expressed concern that pesticides may be a contributing factor to some Gulf War veterans’ unexplained illnesses.

During the past several years, Congressional committees have held numerous hearings and issued several reports on the subject of the health of Gulf War veterans. Several of these reports and hearings made references to various environmental exposures during the war, including pesticides.[9]

Previous investigations into the causes of Gulf War veterans’ illnesses by the Presidential Advisory Committee (PAC) on Gulf War Veterans’ Illnesses[10] and the US Senate’s Committee on Veterans’ Affairs (Special Investigation Unit on Gulf War Illnesses)[11] have considered the possible role of pesticides. In 1996 the PAC concluded, "It is unlikely that health effects and symptoms reported today by Gulf War veterans are the result of exposure to pesticides during the Gulf War." However, the PAC offered a specific comment on lindane, which was used as a delousing agent during the Gulf War: "Lindane is an animal liver carcinogen, but it is too early to see an elevated liver cancer rate in Gulf War veterans."[12]

The Senate Veterans’ Affairs Committee report did not comment conclusively on pesticides’ role in Gulf War Illnesses: "Most troops were likely exposed to some level of a variety of these chemicals although the amount or level of exposure is not known."[13] It is because of these uncertainties that this office made the decision to investigate the use and management of pesticides during the Gulf War and, to the extent allowed by the existing data, estimate the likelihood that the exposure to pesticides may explain the illnesses reported by some Gulf War veterans.

C.  Pesticides of Potential Concern

During the Gulf War deployment, US servicemembers reportedly used or had available for use at least 64 pesticides and related products to provide protection from insects, rodents and other pests. This total includes a variety of products including sprays, powders, baits, and flypaper. These pesticides and related products contain 37 active ingredients, which are the chemical components that kill or control the target pest. Analysts focussed this investigation on 15 pesticides of potential concern (POPCs). These 15 POPCs contain 12 different active ingredients. Some pesticides have different concentrations of the same active ingredient (e.g., DEET 33% cream/stick and DEET 75% liquid). POPCs are believed to have posed the greatest potential hazard to US servicemembers due to manner of use, prevalence of use, and toxicity. Prevalence and manner of pesticide use was based on the RAND survey results and interviews with 252 PM and pest control personnel. [Details on how the list of 15 POPCs were determined are discussed in Part B.2, Data Collection and Evaluation.]

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 "organophosphates" and "organochlorines" 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.

The active ingredients contained in the POPCs, classified as repellents, pyrethroids, organophosphates, carbamates, and organochlorines, are shown in Table 1.

Table 1. Active ingredients contained in pesticides of potential concern

Repellents

Pyrethroids

Organophosphates

Carbamates

Organochlorines

DEET

Permethrin

Azamethiphos

Methomyl

Lindane

 

d-Phenothrin

Chlorpyrifos

Propoxur

 
   

Diazinon

Bendiocarb

 
   

Dichlorvos

   
   

Malathion

   

DEET has been used by US forces since the mid-1950s as an all-purpose repellent applied to the skin and clothing. According to the directions for use, permethrin was only to be applied to uniforms and other articles such as tents, bed and insect netting, and camouflage helmet covers.[14]

Pyrethroids include both natural and synthetic compounds that kill by attacking the nervous system of the insect. Natural pyrethroids are derived from chrysanthemum flowers. The aerosol spray products permethrin and d-phenothrin were the two pyrethroids of concern. Permethrin, although potentially lethal to pests, was used primarily as a repellent. The product d-phenothrin was used in enclosed areas, such as tents, 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 (see Section A.4.B,  General Use Pesticides). Also, Army field sanitation teams, which received only limited training, were authorized to use the organophosphate chlorpyrifos and the organochlorine lindane in their allowances of pesticides contained in their field sanitation kits. [Field sanitation teams are discussed in more detail in Section A.4.C,   Field Use Pesticides]

There were five organophosphates among the POPCs. Azamethiphos was used primarily in a granular form known as "fly bait" against fly populations. Azamethiphos was not, nor is it now, an Environmental Protection Agency approved pesticide. 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 that used for 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 pesticides of potential concern included bendiocarb, methomyl, and propoxur. Bendiocarb and propoxur were used very much like the organophosphate sprays mentioned above. Methomyl was a "fly bait" that was used in the same manner as the organophosphate, azamethiphos. Methomyl has been approved for use by the general public by the Environmental Protection Agency.

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, lindane was also used by some individuals on their clothing.


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