Mortality study of oil refinery workers: five-year follow-up.

A 5-year follow-up of a previous mortality study of 1,207 men employed in a Canadian oil refinery in East Montreal was conducted in an attempt to account for an excess of brain cancer. There were 175 deaths in total. Expected numbers of deaths were estimated based upon age and cause-specific death rates for the province of Quebec applied to person-years of observation. As in the previous study, oil refinery workers showed a standardized mortality ratio (SMR) lower than expected for all causes (SMR = 85.79). The SMRs for cancer indicated an excess of brain cancers in men who died within 20 years of first exposure (SMR = 519.5) and an overall deficit of lung cancers (observed 7 v expected 15.8). A thorough investigation of the several exposures of the brain cancer cases could not relate what seems to be a "cluster" to any hazard encountered at the workplace.