Epidemiological survey of oil distribution centres in Britain.

A mortality study of workers employed for at least one year between 1 January 1950 and 31 December 1975 at oil distribution centres from three oil companies in Britain has been carried out. Ninety nine per cent of the population were successfully traced to determine their vital status at 31 December 1975. The mortality observed in the study population was compared with that which would be expected from the mortality rates for all the male population of England and Wales. The overall mortality observed was considerably lower than expected on this basis as was the mortality from stroke, hypertensive disease, bronchitis, and pneumonia. The observed number of deaths from all neoplasms was also much less than expected as were the observed deaths from lung cancer. The observed deaths from ischaemic heart disease approximately equalled those expected overall and in each of the companies, however, and there was no evidence of a "healthy worker effect" for this disease group. The ratio of observed over expected deaths from ischaemic heart disease tended to decrease with increasing age at death, and for most of the job groups overall, the observed and expected deaths were about the same. Raised mortality patterns from ischaemic heart disease were found in several subgroups of the population of one company. Mortality from myelofibrosis and diseases of the lymphatic and haematopoietic tissue was slightly raised overall. Only myelofibrosis showed an overall excess but raised mortality was found in subgroups of the population defined by company, job, and length of service in several of the other neoplasms making up this disease group. The numbers of deaths from these causes were all small, making it difficult to exclude chance effects. Further work would be required to ascertain whether these results are due to an occupational factor and if so to identify the physical or chemical nature of the risk.