O12.1 HOW HIGH WERE EXPOSURES IN THE AUSTRALIAN PETROLEUM INDUSTRY CASE–CONTROL STUDY?

D. C. Glass¹, C. N. Gray², D. J. Jolley³, C. Gibbons³, M. R. Sim¹, L. Fritschi⁴.¹Monash University, Melbourne, Australia; ²Deakin University, Geelong Australia; ³Deakin University, Burwood, Australia; ⁴University of Western Australia, Perth, Australia

A nested case–control study investigated whether an excess of lymphohaematopoietic cancers identified among the male members of Health Watch was associated with benzene exposure. Cases identified between 1981 and 1999 (n = 79) were age matched to five controls and their benzene exposure retrospectively estimated using occupational histories and local site specific information. The study used the arithmetic mean of measured base estimates (BEs) data supplied by Australian petroleum companies to calculate BE levels for various jobs. These were validated by comparison to literature values. These were then systematically allocated, in a database, to periods of time in the subject’s occupational history. Matched analyses showed leukaemia risk increased at cumulative exposures above 2 ppm years and exposure intensity of highest exposed job over 0.8 ppm. For the 13 case sets with >8 ppm years cumulative exposure, the odds ratio was 11.3 (95% confidence interval 2.85 to 45.1). Risk of non-Hodgkin’s lymphoma and multiple myeloma was not associated with exposure to benzene. The cumulative exposures in this study were much lower than the 50–200 ppm years that is commonly quoted as being associated with risk of leukaemia. Subjects in the study had an average exposure period of 20 years (range 4 to 42). More highly exposed tasks (BE >1 ppm), such as handling benzene or BTX (benzene, toluene, xylene mixture), drum filling, and ship or tanker loading are usually performed for part of …