A critical look at hazards from benzene in workplace and community air

Abstract

Experience in industry over the last half-century suggests that long-term exposure to high concentrations of benzene in the air in the workplace is associated with the occurrence of various blood dyscrasias, including leukemia. It has been stated that no basis exists for the determination of a dose-response relationship for the leukemogenic action of benzene. A critical review of the literature, however, reveals first, that more cases occur at higher concentrations (Hardy and Elkins, 1948; Schonenberger, 1963; Vigliani, 1976); second, that the incidence drops when the level of exposure is reduced (Yllner, 1976; Ikeda, 1976; Aksoy, 1980); and, third and most importantly, that no cases of benzene-induced leukemia have been reported in workers exposed to concentrations that did not exceed 100 and possibly 150 ppm (Jandl, 1977a; Aksoy, 1977; Pagnotto et al., 1979). There are some flaws in the reports which suggest an association between an excess incidence of leukemia in workers and exposure to low levels of benzene. In the context of this presentation, it is not possible to go into detail criticizing those few reports which do suggest such an association and to which reference has repeatedly been made. This critique has been given elsewhere (Lamm and Tabershaw, 1977; Jandl, 1977b; Van Raalte, 1979). A very relevant comment, however, should be repeated here. The authors of those papers suggesting such an association related the reported effects or responses to an at-times-broad range of concentrations, recorded intermittently, to which the subjects had been exposed. With respect to the concentration at the upper end of the range, this is probably justified. The observed effects are known to be associated with exposures at high levels. An entirely different situation, however, exists with regard to the concentrations at the lower end of the range. These were measured at different times. Because of the fluctuating levels in a “range of concentrations” there were probably occasions when even lower concentrations could have been recorded. In the practice of in-