RISK OF CANCER IN FINNISH CHILDREN LIVING CLOSE TO POWER-LINES

Objective-To investigate the risk of cancer in children living close to overhead power lines with magnetic fields of greater-than-or-equal-to 0.01 microteslas (muT). Design-Cohort study. Setting-The whole of Finland. Subjects-8300 boys and 66500 girls aged 0-19 years living during 1970-89 within 500 m of overhead power lines of 110-400 kV in magnetic fields calculated to be greater-than-or-equal-to 0.01 muT. Subjects were identified by record linkages of nationwide registers. Main outcome measures-Numbers of observed cases in follow up for cancer and standardised incidence ratios for all cancers and particularly for nervous system tumours, leukemia, and lymphoma. Results-In the whole cohort 140 cases of cancer were observed (145 expected; standardised incidence ratio 0.97, 95% confidence interval 0.81 to 1.1). No statistically significant increases in all cancers and in leukaemia and lymphoma were found in children at any exposure level. A statistically significant excess of nervous system tumours was found in boys (but not in girls) who were exposed to magnetic fields of greater-than-or-equal-to 0.20 muT or cumulative exposure of greater-than-or-equal-to 0.40 muT years. Conclusions-Residential magnetic fields of transmission power lines do not constitute a major public health problem regarding childhood cancer. The small numbers do not allow further conclusions about the risk of cancer in stronger magnetic fields.