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Aims:To assess mortality and cancer morbidity in Canadian petroleum workers and explore exposure-response relations for specific petroleum agents.Methods:A total of 25 292 employees hired between 1964 and 1994 were linked to the Canadian tumour registry and national mortality database. Exposure-response trends were assessed for hydrocarbon solvents/fuels, hydrocarbon lubricants, petroleum coke/spent catalyst, and hydrogen sulphide (H2S).Results:External comparison analyses (mortality and incidence) showed deficits for all causes and all malignant neoplasms combined and were consistent with expectation for most malignant and non-malignant sites analysed. Gall bladder cancer mortality was increased among males based on four deaths, but cases had no common job assignments and the increase was focused in workers employed <10 years. Mesothelioma incidence was increased. Most exposure-specific analyses were compromised by small numbers. Statistically significant increases were observed for H2S exposure and a subgroup of accidental deaths as well as for petroleum coke/spent catalyst exposure and lung cancer. While both findings have a degree of biologic plausibility, the H2S association, which exhibited a clearer exposure-response pattern, could be subject to unmeasured confounders. Additionally, interpretation was complicated by the high correlation between hydrocarbon and H2S exposures. With regard to lung cancer, the analysis could not adequately control for smoking, was based on small numbers, and exhibited a tenuous exposure-response pattern.Conclusion:The findings for mesothelioma suggest the need for continued attention to asbestos in the petroleum industry. The relation between accidental deaths and H2S exposure deserves closer scrutiny in similarly exposed populations. Further analyses of lung cancer are underway and will be reported separately.

Improved experimental techniques are described, using a wire mesh reactor, for determining the pyrolysis yields of lignocellulosic materials. In this apparatus pyrolysis tars are rapidly swept from the hot zone of the reactor and quenched, secondary reactions are thereby greatly diminished. Particular emphasis is placed upon the measurement of the pyrolysis yields for sugar cane bagasse, an abundant agricultural waste product. The role of the important pyrolysis parameters, peak temperature and heating rate, in defining the ultimate tar yield is investigated, with the value for bagasse being 54.6% at 500 °C and 1000 °C/s. The pyrolysis yields, under similar conditions, of another biomass material, silver birch, are also reported and compared to those of bagasse.

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