Exposure to methyl tert-butyl ether and benzene among service station attendants and operators.

Abstract

Concerns for atmospheric pollution from auto exhaust have led to the blending of "oxygenates" with motor fuels. The most common oxygenate, methyl tert-butyl ether (MTBE) is currently required within several metropolitan areas (Denver and Phoenix) in the range of 12% of the motor fuel. Amendments to the Clean Air Act may expand this requirement to as many as 44 other areas of the United States in the near future. In consideration of the magnitude of potential uncontrolled exposures from its extensive use and a related concern involving the potential influence of MTBE blending on exposures to other constituents of gasoline (particularly benzene), an evaluation of exposures among service station attendants and operators was undertaken at the request, and in cooperation with, the American Petroleum Institute during the latter part of 1990. For application ofthe survey results to a broad audience, three categories or types of service stations were identified with regard to MTBE use and exposure potential: a) service stations that do not use MTBE or use it only as an octane enhancer, b) service stations with seasonal requirements to use 12-15% MTBE (the Denver, Colorado, and Phoenix, Arizona, metropolitan areas), and c) service stations equipped with stage II (active) vapor recovery systems (several coastal areas, most notably Southern California). At the two sampled service stations that use only minimal amounts of MTBE (less than 1%), only 1 of 32 personal breathing zone (PBZ) samples from attendants was above the analytical limit of detection, reported at 0.16 ppm. The geometric mean concentration of benzene among this same population (n = 32) was 0.04 ppm. At the two sampled stations with requirements to use oxygenated fuel, geometric mean MTBE and benzene concentrations were 0.30 and 0.04 ppm, respectively (n = 41). At the two stations equipped with stage II vapor recovery, 16 of 48 PBZ samples for MTBE were detectable, with a geometric mean concentration of 0.09 ppm. The geometric mean benzene concentration at these facilities was 0.06 ppm (n = 48).

Environmental and biological monitoring of benzene during self-service automobile refueling.

“…Only two recent studies provide data regarding the benzene content of different grades of gasoline. In the first of these, regular unleaded gasoline (87-octane) was reported to have the highest benzene content at four of six locations (18), whereas in the second, octane grade was reported to be inversely related to benzene content in two of three cities (68).…”

Toxicokinetics of human exposure to methyl tertiary-butyl ether (MTBE) following short-term controlled exposures

“…The average MTBE concentration of personal breathing zone samples from service station attendants in Phoenix, Arizona, where MTBE content averaged 12.5± 13 LV%, was 0.3 ppm. At the two stations equipped with Stage II vapor-recovery systems in Los Angeles, the average personal breathing zone MTBE levels of attendants was 0.09 ppm (Hartle, 1993 ) . Data from a refueling ( self -service, non -Stage II vapor recovery ) study, with gasoline containing 15% MTBE by volume, indicated that the highest breathing zone air concentration of MTBE was 0.11 ppm, during refueling ( Lindstrom and Pleil, 1996 ) .…”

Hydrocarbon Release During Fuel Storage and Transfer at Gas Stations: Environmental and Health Effects

“…These receptors spend the most time on site (potentially reflecting approximately 40 h per week, for decades) and intermittently spend time where vapors from the pump are at their highest concentrations, with benzene concentrations measuring between 30 and 230 ppb in the breathing zone [38][39][40]. Gas station patrons can also be exposed to vapors when refueling.…”