RELATIONSHIP BETWEEN LOW-LEVEL BENZENE EXPOSURE AND LEUKEMIA IN CANADIAN PETROLEUM DISTRIBUTION WORKERS

This study was conducted to evaluate the relationship between leukemia occurrence and longterm, low-level benzene exposures in petroleum dis tribution workers. Fourteen cases were identified among a previously s tudied cohort [Schnatter et al., Environ Health Perspect 101(Suppl 6): 85-99 (1993)]. Four controls per case were selected from the same coho rt, controlling for birth year and time at risk. Industrial hygienists estimated workplace exposures for benzene, without knowledge of case- control status. Average benzene concentrations ranged from 0.01 to 6.2 ppm. Company medical records were used to abstract information on oth er potential confounders such as cigarette smoking. Odds ratios were c alculated for several exposure metrics. Conditional logistic regressio n modeling was used to control for potential confounders. the risk of leukemia was not associated with increasing cumulative exposure to ben zene for these exposure levels. Duration of benzene exposure was more closely associated with leukemia risk than other exposure metrics, alt hough results were not statistically significant. A family history of cancer and cigarette smoking were the two strongest risk factors for l eukemia, with cumulative benzene exposure showing no additional risk w hen considered in the same models. This study is consistent with other data in that it was unable to demonstrate a relationship between leuk emia and long-term, low-level benzene exposures. The power of the stud y was limited. Thus, further study on benzene exposures in this concen tration range are warranted.