Mortality from cardiovascular disease in relation to magnetic field exposure: findings from a study of UK electricity generation and transmission workers, 1973-1997.
BACKGROUND
Experimental and epidemiological studies have indicated that magnetic field exposure might influence heart rate variability and consequent risks of arrhythmia related deaths.


METHODS
The mortality experience of a cohort of 83,997 employees of the former Central Electricity Generating Board (CEGB) of England and Wales was investigated for the period 1973-1997. Cohort members were employed for at least 6 months from 1973 to 1982. Computerized work histories were available for 79,972 study subjects for the period 1971-1993. 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 standardization (n = 83,997) and Poisson regression (n = 79,972).


RESULTS
Based on serial mortality rates for England and Wales, deaths from four categories of cardiovascular disease were below expectation: arrhythmia-related disease (ICD-9 426-7), observed (obs) 32, expected (exp) 43.5, standardized mortality ratio (SMR) 74; acute myocardial infarction (ICD-9 410), obs 3,320, exp 3878.3, SMR 86; atherosclerosis (ICD-9 440), obs 25, exp 39.2, SMR 64; chronic/sub-acute coronary disease (ICD-9 411-414), obs 1,552, exp 2021.7, SMR 77). No statistically significant trends were shown for risks of any of these four disease groupings to increase 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 mortality from cardiovascular diseases as a consequence of occupational exposure to magnetic fields in UK electricity generation and transmission workers.
Sorahan
Tom
T
Institute of Occupational Health, University of Birmingham, Edgbaston, Birmingham, United Kingdom. T.M.Sorahan@bham.ac.uk
Nichols
Linda
L
D000328:Adult; D001145:Arrhythmias, Cardiac / Q000453:epidemiology / Q000209:etiology; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology / Q000401:mortality*; D015331:Cohort Studies; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004739:England / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology / Q000401:mortality*; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D016012:Poisson Distribution; D011210:Power Plants; D014852:Wales / Q000453:epidemiology; D000078329:Workforce