Cancer incidence in UK electricity generation and transmission workers, 1973-2008

Background The effects of magnetic field exposure on cancer risks remains unclear. Aims To examine cancer incidence among a cohort of UK electricity generation and transmission workers. Methods Cancer morbidity experienced by a cohort of 81 842 employees of the former Central Electricity Generating Board of England and Wales was investigated for the period 1973-2008. All employees had worked for at least 6 months with some employment between 1973 and 1982. Standardized registration ratios (SRRs) were calculated on the basis of national rates. Results Overall cancer morbidity was slightly below expectation in males and females. Significant excesses were found in male workers for mesothelioma (Observed [Obs] 504, SRR 331), skin cancer (non-melanoma) (Obs 3187, SRR 107) and prostate cancer (Obs 2684, SRR 107) and in female workers for cancer of the small intestine (Obs 10, SRR 306) and nasal cancer (Obs 9, SRR 474). Brain cancers were close to expectation in males and below expectation in females. Leukaemia incidence (all types) was slightly below expectation in males and females. More detailed analyses showed important contrasts for mesothelioma and leukaemia. Conclusions The clear occupational excess of mesothelioma was not matched by a corresponding excess of lung cancer, and the level of asbestos-induced lung cancer in this industry must be low. Leukaemia risks declined with period from hire; confident interpretation of this finding is not possible. The excesses of cancers of the nasal cavities and small intestine are probably not occupational, though the excess of skin cancer may be due to outdoor work.