Petroleum fuels are a complex mixture of aliphatic hydrocarbons and aromatic hydrocarbons such as benzene and PAHs. These fuels also commonly contain various additives, like lead. When burned, petroleum fuels produce a variety of potentially hazardous combustion products. High-level, short-term exposures to fuel solvents can cause immediate effects. In most cases, however, complete recovery occurs when the exposure ceases.5,286

U.S. service members could have been exposed to petroleum fuels by inhalation, ingesting contaminated water or dust, and skin contact. Inhalation exposure could depress the central nervous system (CNS). Symptoms include short-term effects ranging from fatigue, headache, nausea, blurred vision, and dizziness, to convulsions, paralysis, and loss of consciousness depending on the dose.282,312 Again, exposure to high, nonlethal levels usually is followed by complete recovery, although rare cases of permanent brain damage after massive exposure have been reported.117,205,282

Prolonged breathing of diesel fuel vapors can damage kidneys or lower blood clotting ability.284 Studies of workers occupationally exposed to certain hydrocarbon solvents in petroleum fuels suggest that long-term high-dose exposure over 12 to 14 years can lead to neurotoxic effects.117,285 For example, psychomotor disturbances, visual memory and perception, and visuomotor learning ability were significantly affected in exposed gasoline-pump workers compared to matched controls, particularly workers exposed for more than a year.125 Some studies suggest there are neurotoxic effects from long-term exposure, including decrements in memory, cognitive functioning, and sometimes neuromotor functions.117 Other researchers, however, have challenged the existence of what is sometimes referred to as "chronic toxic encephalopathy," and uncertainty exists about CNS effects from long-term, low-level exposures to solvents.69

Benzene makes up about one percent of U.S. gasoline and up to five percent of European formulations. It is a known human carcinogen that is associated with certain types of leukemia. Nevertheless, more than 55 published epidemiologic studies of workers exposed occupationally to hydrocarbons such as gasoline generally do not replicate the carcinogenic effects reported for experimental animals.157,282 Recent studies of refinery workers also do not reveal a clear association between gasoline production and leukemia.88,282 Still, based on the limited evidence from animal studies and the presence of benzene in gasoline, the International Agency for Research on Cancer (IARC) concluded that gasoline is possibly carcinogenic to humans. It is not known if other petroleum products cause cancer in humans. IARC believes there are insufficient data to assess whether light fuel oils or light diesel fuels cause cancer in humans. However, IARC has determined that occupational exposure to fuel oils during petroleum refining is probably carcinogenic to humans.284

Although ingesting small amounts of fuel oils is unlikely to cause significant symptoms, ingesting fuel oils in larger quantities can cause vomiting, diarrhea, swelling of the stomach, stomach cramps, coughing, drowsiness, restlessness, irritability, and unconsciousness.284 Ingestion of fuel oils can be accompanied (during vomiting) by aspiration of some of the material into the lungs, which can produce a chemical pneumonitis.

Skin exposure to large amounts of oil can physically clog pores and hair follicles, compromising body heat loss. Long-term exposure can cause acneand other skin problems. With high concentration or extended exposure, lighter components of crude oil or other fuel oils can defat the skin, leading to redness and itching or dermatitis.284,312

Exposure to the normal combustion products of petroleum fuels is also a health concern. Limited epidemiologic evidence indicates daily use of kerosene stoves for cooking or heating does not cause breathing problems for most people.284 If insufficiently vented, however, carbon monoxide generated from fuel oil combustion can build up, causing drowsiness, nausea, and even asphyxiation. Individuals exposed to unvented combustion of fuels containing lead could experience health effects ranging from subtle biochemical changes in blood to severe CNS effects at high doses. Occupational exposure to inorganic lead is associated with subjective signs of neurotoxicity such as forgetfulness, lethargy, and weakness. These neurological signs and symptoms occur at about the same blood lead levels as other overt signs of lead intoxication, such as gastrointestinal complaints like abdominal pain, nausea, and vomiting.286

While certain subsets of Gulf War service members could have experienced occupational exposures to petroleum products that would entail increased risks of health effects, it is unlikely that health effects reported today by Gulf War veterans are due to exposure to petroleum products during the war.