Case-Control Studies of Cancer in New Zealand Electrical Workers

Pearce N (Department of Community Health, Wellington School of Medicine, Wellington Hospital, Wellington, New Zealand), Reif J and Fraser J. Case-control studies of cancer in New Zealand Electrical Workers. International Journal of Epidemiology 1989, 18: 55–59. A series of reports, including a New Zealand case-control study, have suggested that electrical workers are at increased risk of leukaemia. We report here a further series of case-control studies based on the New Zealand Cancer Registry. These involved 19 904 male patients registered with cancer for the period 1980–1984 who were aged 20 years or more at time of registration. For each cancer site, the registrations for other sites formed the control group. Three main findings emerged. First, there is an elevated leukaemia risk in New Zealand electrical workers (odds ratio (OR) = 1.62, 95% confidence interval (CI) 1.04–2.52), but little evidence of increased risks for other cancer sites. Second, contrary to other published studies, the increased risk was primarily for chronic leukaemia (OR = 2.12) rather than acute leukaemia (OR = 1.25), and for lymphatic leukaemia (OR = 1.73) rather than myeloid leukaemia (OR = 1.22). Third, the increased risk was strongest for certain categories of electrical work including radio and television repairers (OR = 7.86, 95% CI 2.20–28.09), electricians (OR = 1.68, 95% CI = 0.75– 3.79), linemen (OR = 2.35, 95% CI 0.97–5.70) and power station operators (OR = 3.89, 95% CI 1.00–15.22).