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-%[3 MOTM GASOLINE <br /> 65-19 <br /> I� <br /> comaonents (e 9 --aphthalene and methpinapnthalane) by =__^ and do• <br /> mastic animals. 4hich may also result in human exaosurLs to the <br /> bzoconcentracion of these co=oonenrs. <br /> Ground water conc=inated With gasaline can Lead to inhalation <br /> exposures in homes using this wacer-. In one szudv of homes in !'lain <br /> (2313) , concentrations of total benzene, toluene and xylene measured in <br />{ axr of the closed bathrooms whXle hot showers were ru*++++ng were 2.05. <br /> 3 15, and 30 ppm in homes with 6, 3, and 20 ppm, -respectively,- of total - <br /> hydrocarbons in cheer water. In the ttiro homes with the highest total <br /> concentrations. xylene accounted for roughly 63% of the concenrrazian <br /> In air, toluene 29-32a and benzene 5-9t; in the other home 951 was <br /> benzene, the rest toluene. The author of this study suggested that <br /> odor MAY be a sensitive indicator of gasoline contamination is vater. <br /> In the houses with high hydrocarbon contamination. an offensive odor <br /> was noticeable, especially during sampling (2313) . Even though no <br /> benzene, toluene or xyLene was detected in the air of threa homes with <br /> less than 0 5 ppm total hydrocarbons in their water, in two of these <br /> homes gasoline odors were present in the bathroom. However, a <br /> modelling study (231.4) indicates that petroleum-based pollutants <br /> (benzene, toluene, xylene) present in wacer at 5 to 50 ppb--levels <br /> below detectable taste or odor threshholds--may result in peak air <br /> concentrations that cause mucous membrane irritation. <br /> Volatilization of gasoline hydrocarbons in soil is another <br /> a_ potential source of human exposure. This exposure pathway is ILksly to <br /> be more significant for gasoline than other petroleum products because <br /> of its high voLatility. Eupoaurms may be more intrans tvQ when tho soil <br /> Ls concaminacad directly from leaking underground storage canEw and <br /> Pipes, rather than from surfaera spills. In such canna, thea metro <br /> volatile components do not have an opportunity to evaporaea bofore <br /> penetrating the soil. Once in tha soil, the hydrocarbons evaporate <br /> saturating the air in the soil pores, and diffusing in all directions <br /> including upward to the soil surface. The vapors may diffuse into the <br /> basement of homes or other scr=tures in the area resulting in <br /> Inhalation exposures to the building's occupants. <br /> 65.2.4 Other Sources of Hunan Exposure <br /> 4 <br /> Data on ambient concentrations of gasoline in air and wacar as <br /> well as food and drinking water are not readily available in the <br /> literature. Exposure infarmatian on specific components may be found <br /> in other chapters of the IRP Toxicology Cuide. <br /> L <br /> The volatile nature of automotive gasoline suggests char <br /> inhalation may represent- a significant exposure pathway. The average <br /> concentrations of aucoaccive gasoline co which residancs of communities <br /> near bulk terminals. bulk plants, and service stations (employing no <br /> spacial controls) are exposed neva been estimated as L.41, 0.073, 0.026 <br /> ppm, respectively (2311) . It should be emphasized that these values <br /> are averaged over a lifetime and in all cases the concentrations are <br /> estimated from emission rates. Exposure co service station employees <br /> and individuals filling their tanks at self-service operations are much <br /> 6/87 <br />