Studies in humans and animals have shown that gasoline contains a number of cancer-causing and toxic chemicals such as 1,3-butadiene, benzene, toluene, ethylbenzene, xylenes, isoparaffins, methyltert-butylether, and others. The International Agency for Research on Cancer (IARC) in its Monograph Supplement 7 (1987) concludes that "in the absence of adequate data on humans, it is biologically plausible and prudent to regard agents for which there is sufficient evidence of carcinogenicity in experimental animals as if they present a carcinogenic risk to humans." Epidemiological studies in humans provide important evidence of potential increased risk of leukemia, lymphatic tissue cancers, cancers of the brain, liver, and other organs and tissues. Recently (July, 1990) the American Conference of Governmental Industrial Hygiene (ACGIH) recommended that the TLV-TWA for benzene be reduced from 1 ppm to 0.1 ppm (ACGIH, 1990). The Collegium Ramazzini and others have also recommended that the exposure level for 1,3-Butadiene be reduced from 1,000 ppm to below 0.2 ppm. This recommendation is based on the findings that were presented at the Symposium on Toxicology, Carcinogenesis, and Human Health Aspects of 1,3-Butadiene (Environ. Health Perspec., 1990). Thus, studies on health effects resulting from very low levels of benzene, 1,3-butadiene, and other cancer-causing chemicals--components of gasoline--necessitate that all avoidable exposure to gasoline or gasoline vapors be avoided.