Occupational exposure to magnetic fields relative to mortality from brain tumours: updated and revised findings from a study of United Kingdom electricity generation and transmission workers, 1973-97

OBJECTIVE: To investigate whether risk of brain tumour is related to occupational exposure to magnetic fields. METHODS: The mortality experienced by a cohort of 83 997 employees of the former Central Electricity Generating Board of England and Wales was investigated for the period 1973-97. All workers were employed for at least 6 months with some employment in the period 1973-82. Computerised work histories were available for 79 972 study subjects for the period 1971-93. Detailed calculations had been performed by others to enable a novel assessment to be made of exposures to magnetic fields. Two analytical approaches were used, indirect standardisation (n=83 997) and Poisson regression (n=79 972). RESULTS: Based on serial mortalities for England and Wales, deaths from brain cancer were close to expectation (observed 158, expected 146.4). No significant positive trends were shown for risks of brain tumours either with lifetime cumulative exposure to magnetic fields or with such exposures received in the most recent 5 years. CONCLUSIONS: There are no discernible excess risks of brain tumours as a consequence of occupational exposure to magnetic fields in United Kingdom electricity generation and transmission workers.