An update of a cohort study of 14 074 employees at the Richmond and El Segundo refineries of Chevron USA in California was conducted to further examine mortality patterns. The update added six years of follow up (1981-6) and 941 deaths. As in the previous study, mortality from all causes (standard mortality ratio (SMR) = 73) was significantly lower among men compared with the general United States population. Significant deficits were also found for all cancers combined (SMR = 81), several site

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... specific cancers, and most non-malignant causes of death. Mortality from suicide was increased relative to the United States as a whole. Based on a comparison with California rates, however, men had fewer deaths from suicide than expected. Standard mortality ratios were raised for several other causes of death, but only leukaemia and lymphoreticulosarcoma exhibited a pattern suggestive of an occupational relation. The increase appeared to be confined to those hired before 1949, and in the case of lymphoreticulosarcoma, to Richmond workers. In 1983, a mortality study of current and former Chevron employees at the Richmond and El Segundo refineries was completed.' The observation period of the original study extended from 1 January 1950 to 31 December 1980, and comprised all employees who worked at least one year at either refinery (a day of which had to fall within the