This report reflects the current body of knowledge on the use of pesticides, the levels of exposure experienced by various groups of Gulf War veterans, the potential health effects associated with these exposures, and the lessons learned on the use, application, and management of pesticides by military personnel.
Because of the unavailability of data in several key areas of the investigation, assumptions and estimates based on likely exposure scenarios were required to complete the health risk assessment (HRA) segment of this report. While following an accepted methodology, the necessary use of many assumptions to estimate exposure doses adds to the uncertainty associated with the HRA findings and conclusions, and reduces the scientific rigor normally found in analyses where definitive measurements are taken. As a result the HRA, as described in this report, cannot be used to prove either that pesticide overexposures occurred during the Gulf War, or that any connection exists between pesticide exposures and chronic health effects months or years after exposure. Conversely, the HRA cannot be used to reasonably assert that pesticides do not play a role in causing or contributing to some of the as-yet undiagnosed illnesses reported by some veterans.
These limitations notwithstanding the results of the overall analysis benefit our understanding of the issues related to the militarys use of pesticides. For example, a number of findings and conclusions reached in this report will not only benefit pesticide handling and management activities in future deployments, but will also provide some indication as to where DoD may wish to conduct additional research to better define health risks under conditions that previously may not have been suspect.
Conclusions relating specifically to potential health outcomes from pesticide exposures include the following:
Troops used pesticides for a number of reasons, including skin and uniform application to repel insects, as area sprays and fogs to kill flying insects, in pest strips and fly baits to attract and kill flying insects, as surface sprays, and as delousing agents applied to enemy prisoners of war to control typhus.
The most important pesticide active ingredients used by US personnel during the Gulf War fall into five major categories: 1) organophosphates; 2) carbamates; 3) the organochlorine, lindane; 4) pyrethroids; and 5) the insect repellent DEET. The Environmental Protection Agency approved all of the pesticides obtained through the military supply system. However, some pesticides purchased locally, such as the azamethiphos-based fly bait, are not approved for general use by the Environmental Protection Agency.
There were select groups of military personnel, totaling about 3,500 to 4,500 individuals, who, because of their job responsibilities, were potentially at greater health risk from pesticide exposure. These included trained and certified pesticide applicators, field sanitation teams, and military police who conducted delousing operations. There does not appear to have been an appreciable risk from exposure to pesticides to the general military population.
The scientific literature search completed by RAND suggests that pesticides, specifically acetylcholinesterase (AChE) inhibitors such as organophosphates and carbamates, could be among the potential contributing agents to some of the undiagnosed illnesses reported by Gulf War veterans. Therefore, exposure to these pesticides cannot be ruled out as a potential contributing factor to some of the undiagnosed illnesses seen in Gulf War veterans. The RAND report also notes that it is unlikely that exposure to these pesticides is the sole explanation for the myriad of health problems reported by Gulf War veterans, as few veteran symptoms are uniquely characteristic of pesticide exposure alone.
Organophosphate and carbamate pesticides have the potential to cause long-term symptoms somewhat similar to those reported by some veterans. There is conflicting information in the literature, however, over the issue of whether long-term effects can be seen in individuals who have not experienced short-term symptoms. Some sources in the literature suggest that unless individuals had symptoms of serious pesticide poisoning or toxicity from organophosphate and carbamate pesticides at the time of the initial exposure, health effects months or years later are unlikely. RAND, however, concludes from their literature review that short-term symptoms are not necessarily a precursor to long-term effects.
According to the RAND literature review, some of the general long-term symptoms which have been reported by some veterans with undiagnosed illnesses, and also reported in highly pesticide-exposed individuals (not Gulf War veterans) include: memory and concentration problems, irritability, pain, fibromyalgia, chronic fatigue, and sleep disorders.
Based on a preliminary review, only one documented instance of acute health problems from pesticide exposures has been found in Gulf War hospital and personnel medical records. A recent follow-up interview with the veteran revealed that he is currently not suffering from any adverse health effects associated with the exposure. When other records are fully cataloged in an automated system other evidence of acute exposures and related symptoms may be found. Further research in the area would be a useful undertaking as there have been reports by some Gulf War veterans that they witnessed or experienced adverse health effects due to pesticides while in the Gulf, and several recounted instances where medical treatment was required.
OSA investigators completed a scientifically peer-reviewed HRA to estimate exposures and some possible health consequences. In conjunction with information from other studies, the HRA aids in the identification of groups of veterans who because of their occupational specialty during the deployment may have been at high risk from pesticide exposure. It may help shed light on the potential for acute and chronic adverse health effects. Investigators and peer-reviewers consider many of the assumptions that were included in the HRA to be very conservative, thus tending to overestimate exposures. Nevertheless, the HRA demonstrates that the opportunity for exposure to some pesticides existed and suggests that some veterans may have been exposed to levels of pesticides that exceeded the levels of concern as defined here. As a result, and because of the lack of data and evidence to the contrary, it is possible that these exposures may have been a contributing factor to some of the unexplained illnesses reported by some veterans.
A significant number of the approximately 3,500 to 4,500 veterans involved in handling and application of pesticides, may have been at elevated risk for short-term health effects. In addition, we estimate that approximately 30,500 members of the general military population may also have been at elevated risk for short-term health effects because of their exposure to pest strips. A third group, numbering about 7,000 of the general military population, may have been over exposed to pesticides applied during area spraying operations. Although there may be a little double counting, OSA considers it likely that at least 42,000 servicemembers overall may have been overexposed to pesticides during the Gulf War.
According to the RAND survey, a subgroup consisting of up to roughly 54,500 servicemembers used or witnessed the use of fly baits. It is difficult to determine the subgroup of fly bait users who may have been overexposed as the data does not differentiate between indoor and outdoor use, nor does the data differentiate users from those who report they saw fly baits used. It is those who used the product indoors who are considered to have been at risk.
The results of the HRA were hampered by the lack of quantitative data on the amount of pesticides used during the Gulf War, and the levels of pesticides present in the air and on surfaces to which US troops were exposed. The investigation also lacked information from veterans hospital and medical records. Collectively this lack of data resulted in significant uncertainties existing in the findings and conclusions of the HRA. To reduce these uncertainties and to better characterize the risk from pesticide exposure, further research is needed in several key areas, including: effects of low-level pesticide exposures; pesticide interactions with other chemical compounds such as pyridostigmine bromide; record searches of over 28,000 patient records for evidence of pesticide poisoning and overexposure; and epidemiological studies involving pesticide applicators.
The HRA does not account completely for some potentially important combined exposures. While it accounts to some extent for combinations of organophosphate and carbamate pesticides, it does not fully account for additional concurrent exposures to DEET, permethrin, pyridostigmine bromide, and nerve agents.
Some individuals are more susceptible to the effects of pesticides than others. This may be due to several factors, including genetic make-up. For example, some individuals may be more efficient at detoxifying and clearing pesticides than others.
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