As discussed in sections VI and VII above, there is no evidence that either high or low levels of exposure of US troops to chemical agents occurred, and there is no indication from research that there would be chronic sequelae from low level exposure even if it had occurred.
B. Biological Agents
While Iraq has been assessed as having had an active offensive BW program, there is no evidence for the deployment of BW during ODS. The diseases associated with BW agents, e.g., anthrax, botulinum, etc., are notable for acute effects and would have been rapidly evident and readily diagnosed had they occurred among US or coalition troops during the war.
C. Infectious Disease
By any previous standards, casualties from infectious diseases were extremely low during Desert Shield/Desert Storm, reflecting effective application of preventive medicine doctrine and good discipline. Food and water-borne diseases and vector borne diseases have, in the past, caused very high casualties to armies in that region. The major causes of morbidity from infectious diseases were self-limiting diarrhea and respiratory illnesses. Low overall enteric disease rates testify to safe food supplies and food preparation and effective water purification methods. The virtual absence of vector-borne viral diseases such as sandfly fever and only 7 cases of malaria appear to be the result of a combination of vector control, personal protection, and climatic factors.,
One vector-borne parasitic disease, leishmaniasis, has been suggested as a potential cause in later development of chronic unexplained illness. The leishmania species present in the theater can cause self limiting skin infections (cutaneous leishmaniasis), severe visceral disease (kala azar) and, a chronic disseminated infection without obvious skin lesions or major organ involvement.
Thirty-one cases of leishmaniasis contracted in the theater have been diagnosed in military personnel. Nineteen cases were cutaneous disease and 12 were disseminated disease. Clinical and parasitologic studies by Army investigators have defined the spectrum of illnesses caused by Leishmania tropica, the predominate Leishmania species in the region. The cases of disseminated viscerotropic illnesses caused by this species was a surprising new observation leading to the hypothesis that there may be additional cases of cryptic infections causing chronic illness that cannot be diagnosed by current parasite isolation or serologic methods.
There was some evidence for clustering of leishmaniasis cases in units -- not unexpected since transmission is by sandfly vectors. The reported studies are clinical, parasitologic and immunologic studies and do not address the epidemiology of the disease in DS/DS. Also lacking are data on the distribution of sandfly vectors in the theater, although information presented by a Navy entomologist with the DoD Pest Control Board indicated that some surveys had found very little evidence for large numbers of the sandfly in areas of high troop concentrations. 
A possible role for leishmaniasis in later unexplained illness has been suggested, but additional studies are warranted to rule out such chronic infections which result in very little antibody and are difficult to diagnose. Development of more sensitive and less invasive diagnostic methods is an important research effort that will help to define the full extent of disease due to leishmania parasites and determine whether Leishmaniasis is a significant contributor to the chronic unexplained illness. The lack of outbreaks of sandfly fever probably indicates a low overall exposure to sandfly bites. A comprehensive epidemiologic study, however, should include a study of the distribution of leishmaniasis cases.
Contaminated lettuce from local vendors was described as having led to outbreaks of diarrhea. Additionally, although standard sanitary practices were in place, it is probable that some of the incidence of diarrheal disease was related to contaminated water, foods or utensils. Giardia lamblia can be a cause of prolonged, watery diarrhea in veterans returning from areas where the water supply has been contaminated, although the task force did not receive information that this had been noted through surveillance of Gulf War veterans.
There were many instances of respiratory ailments beginning, or being aggravated by the living and working conditions for troops in Saudi Arabia. In one instance, troops occupying a long-vacant Saudi housing area in Al Eskan experienced significant rates of respiratory disease due to the fine sand and dust from accumulated pigeon droppings.  The disease was described as self-limiting, and while it is possible that some individuals who experienced this condition may have developed chronic sequelae, the extent of the conditions precipitating these cases does not provide an explanation for most of the veterans with undiagnosed medical complaints.
D. Environmental/Occupational Pollutants
The very nature of warfare exposes combatants to a variety of hazardous substances, not the least of which is flying steel, shrapnel and blast overpressures from conventional warfare munitions. Most exposures during the Desert Shield/Storm time frame involved materials of lesser toxicity; Several situations of note included exposures to petroleum products, pesticides and CARC (Chemical Agent Resistant Coating) paint.
1. Petroleum Products
While a wide variety of fuels, lubricants and solvents were present routinely in many situations during the operation, it is not clear that exposures were different than soldiers encounter during peacetime military operations and training.
2. Alcohol Substitutes
No inquiry has been made on the extent of substance abuse (e.g., solvent sniffing, etc.) in a population that was abruptly deprived of alcohol. Some troops in the Vietnam war are known to have injured themselves by ingesting RDX, a plastic explosive, and a small number of individuals are bound to have experimented with these and other substances.
The Task Force received information regarding the use of pesticides used for vector-borne or rodent disease prevention and control. All such materials used by military are EPA approved, and applied by trained technicians. Relative quantities of pesticides available to deployed units can be deduced from supply records, but application records do not exist.
Common pesticides used included d-phenothrin, chlorpyrifos, resmethrin, malathion, methomyl, lindane, pyrethroids and DEET.
There are potential acute adverse effects from pesticide poisoning; organophosphates can cause headache, diarrhea, dizziness, blurred vision, weakness, nausea, cramps, discomfort in the chest, nervousness, sweating, miosis (pinpoint pupils), tearing, salivation, pulmonary edema, uncontrollable muscle twitches, convulsions, coma, and loss of reflexes and sphincter control. Nausea, incoordination, and eye and skin irritation can occur following acute pyrethroid exposure. Polyneuropathy can occur 2-3 weeks following high-level exposure to some organophosphates (malathion, chlorpyrifos).
While some individuals may have experienced some effects from local pesticide use, there were no reports of acute pesticide poisoning during the war. If continued analysis of the VA registry indicates a higher incidence of neurophysical disorders in those veterans whose duties included routine application of pesticides, pesticide exposure may come under closer scrutiny as an etiological factor for other participants.
4. Oil Well Fires
On February 23, 1991, Iraqi forces began to destroy and set on fire more than 700 oil wells throughout Kuwait. All the fires were extinguished and the wells were capped by early November, 1991, but there was great concern regarding the potential health risk to personnel in the region as a result of their exposure. , , , 
During the 8 month period in which the oil wells were burning, numerous efforts were undertaken to assess the air quality over Kuwait and to determine the health risks posed to the populations living, working, and serving in the military in the region. The U.S. Interagency Air Quality Assessment team arrived in Kuwait in March 1991 to begin to assess the possible health effects of the smoke from the oil fires. This team was composed of scientists from the U.S. Environmental Protection Agency, the National Oceanographic and Atmospheric Administration, and the Department of Health and Human Services.
During the period of the fires, the measured levels of two major air pollutants (sulfur dioxide, nitrogen dioxide) did not reach harmful levels. The level of particulate matter measuring less than 10 microns (PM10), that portion of airborne particulate with the greatest impact on the respiratory system, did exceed the U.S. "alert level" on several occasions. However, Kuwait has frequent sand and dust storms, and the average level of PM10 in Kuwait is nearly 600 ug/m3, the highest in the world.
The hazards to the soldiers posed by the smoke were largely dependent on the concentration of the pollutants in the air near the camps. Fortunately, the plumes resulting from the fires rose up to 10,000 to 12,000 feet, mixing with the air and then being dispersed for several thousand miles downwind over a period of several weeks. As the plume traveled, the particles and gases contained within it became more widely dispersed and also more diluted. The highest concentrations were in the areas nearest the affected oil fields and the areas immediately downwind. Few soldiers were in those areas for long periods of time. Considerable dilution took place over space, such that by the time the plume reached areas of troops in Saudi Arabia, it was far less visible and less concentrated than in Kuwait
Potential effects on the respiratory system, such as a small loss in lung function or the development of chronic bronchitis, would be of particular concern to those who were exposed for many months to severe particulate pollution. These effects might be more likely to occur in cigarette smokers.
The US Army Environmental Hygiene Agency report of its participation in ODS provides some useful insights regarding industrial hygiene, preventive medicine and the impact of oil fires on health issues. The report cites no incidents regarding exposure to chemical weapons agents. Principal USAEHA efforts were to evaluate the health effects risks due to oil fires. On the basis of air and soil pathway analysis, excess cancer risk resulting from exposure to the Persian Gulf environment ranged from 2 to 5 per 10,000,000 well below the EPA range of concern of 1 per 10,000 through 1 per 1,000,000. The cancer risk assessment was based primarily on the risk from chromium. There was little difference in risk levels found between Saudi permanent monitoring sites and those in Kuwait near the oil fires. These results were based on collection of over 4,000 samples at 10 fixed ground sites over a period of seven months beginning in May 1991.
Additionally, the National Center for Environmental Health, Centers for Disease Control and Prevention, performed surveys of VOC (volatile organic compounds) in the whole blood of two groups; American personnel employed in Kuwait City, about 20 km from the burning wells, and firefighters and medical personnel working at the burning oil wells.[2l] Concentrations were compared to those of a random sample of persons in the United States. Median concentrations of the first group were equal or lower than those of the reference group; the firefighters did have elevated levels of some VOCs over those of the reference group. Since US military personnel were not involved directly in the fire fighting operations, their exposures would have been more comparable to those study personnel in Kuwait City, who showed no elevation in VOC level.
Because many US troops trained, executed maneuvers and actually lived out in the desert, there was initial concern for the possible adverse effects of being exposed to high levels of blowing and suspended sand. The sand was often powdery in consistency, and some personnel with respiratory problems did experience aggravated symptoms. An epidemiologic survey conducted among 2598 men stationed in northern Saudi Arabia, however, found that the type of structure in which a person slept may have been as important a risk factor for developing respiratory complaints as exposure to outdoor air pollutants. The personnel who slept in air-conditioned buildings, for example, were much more likely to develop a cough and sore throat than those who lived in tents and warehouses.
It is reasonable to expect that inhalation of particulate matter could have resulted in some short-term airway irritation, and could have aggravated personnel with asthmatic conditions that were previously minor or asymptomatic. While little is known specifically regarding the long-term effects of inhaling fine sand, it does not seem likely to be a major contributing factor to the complex of symptoms being reported by veterans.
6. CARC (Chemical Agent Resistant Coating) Paint
Chemical agent resistant coating (CARC) used to paint combat vehicles and equipment, releases toluene diisocyanate during the curing process. Some civilian workers and several support units may have conducted painting without required respiratory protection. The extent of such exposures are unlikely to be a factor for the majority of personnel suffering from unexplained symptoms.
E. Medical Prophylaxis
Protective measures taken to prevent chemical or biological warfare casualties included vaccination against anthrax and botulinum toxin and prophylactic use of pyridostigmine as a nerve agent pretreatment. No evidence has been found to implicate any of these measures in the unexplained medical complaints in Gulf War participants.
1. Pyridostogmine Bromide
Pyridostigmine Bromide (PB) was issued as a nerve agent pretreatment to nearly an US troops, as well as 45,000 participants from the United Kingdom. Use of low doses (30mg 3x daily) of PB, taken orally upon direction of unit commanders, confers significant protection to troops when used with the other post-attack treatment measures (atropine and 2-Pam chloride). Although all units were given PB, the Department of Defense does not have records of which military personnel actually ingested PB, nor of how many tablets may have been ingested.
Most of the extensive clinical experience with the drug in civilian medicine has been with patients suffering from myasthenia gravis, a neuromuscular disorder. These patients are given doses as high as ten times those taken by troops. Metabolic and toxicologic studies and the relatively small amount of drug actually taken by military personnel make pyridostigmine an extremely unlikely contributing factor in the unexplained medical complaints in Gulf War participants.
The Army is preparing a formal NDA (new drug application) submission specifically for the indicated application of CW prophylaxis. The FDA procedures will entail a thorough and formal reexamination of the toxicological, metabolic and epidemiological data. While it is extremely difficult to rule out idiosyncratic side-effects at the level of 1 per thousand or fewer of those exposed, this hypothetical concern should be weighed against the hazards of unprotected exposure to chemical attack.
2. Anthrax Vaccine
Anthrax vaccine was administered to about 150,000 troops in the theater, about 1/5 of those deployed. The licensed anthrax vaccine, produced by the Michigan State Department of Public Health, has been extensively used for years in civilian wool factory workers and laboratory workers, and its safety is well documented.
3. Botulinus Toxoid Vaccines
Botulinus toxoid administration was restricted to relatively few units that were thought to be at highest risk. Only about 8000 doses were administered, but hardly any to reservists, which group is prominent among those reporting symptoms. This vaccine is made by the same process as tetanus toxoid that is used in infants worldwide, and is also produced by the Michigan State Department of Public Health.
Operation Desert Storm was the first conflict that involved the use of depleted uranium (DU) munitions. Armor piercing projectiles fired from tanks and A-10 aircraft consisted of DU kinetic energy penetrators, enabling U.S. forces to engage and kill enemy vehicles at standoff ranges that enhanced their own safety.
Concern has developed around the possibility that expended DU projectiles, or the dust and fragments from them, posed a residual hazard to troops on the battlefield. Additionally there are a limited number of US soldiers whose vehicle was struck by friendly fire, resulting in DU shrapnel wounds. These soldiers are being followed up by a long-term study that will examine possible chronic effects from embedded DU fragments.
The other highest probability exposures from DU are among a group of maintenance workers who cleaned out a US tank that had been struck by enemy fire and burned while carrying DU ammunition. Careful radiological monitoring of these individuals during and after exposure led to the conclusion that the residual DU particles posed a minimal hazard to personnel working around contaminated vehicles with appropriate protection.