RADIUM IN DRINKING-WATER AND THE RISK OF DEATH FROM BONE CANCER AMONGONTARIO YOUTHS

Objective: To determine whether residents of Ontario who an exposed to radium 226 naturally occurring in drinking water are at increased ris k of bone cancer. Design: A population-based case-control study of rec ords from death and birth registries. Water samples were obtained from residences at the time of birth and of death. Setting: Ontario. Parti cipants: All Ontario-born people under the age of 26 years who died of bone cancer between 1950 and 1983. Control subjects were those who di ed of any other disease matched by age, sex and year of death. Outcome measures: Radium exposure distributions and estimation of risk. Resul ts: An association was found between death from bone cancer and exposu re to radium at the birthplace residence in concentrations of 7.0 mBq/ L or more (odds ratio 1.58, 90% confidence interval [CI] 1.01 to 2.50; p = 0.047). There was a statistically significant exposure-response r elation (p = 0.045). The increase in risk was similar for the main typ es of childhood bone cancer: osteosarcoma, Ewing's sarcoma and chondro sarcoma. Conclusions: The estimated risk at these exposure levels is m uch higher than would be predicted. The association may be spurious, t he point estimates of risk may be too high, or risk factors derived fr om other exposure circumstances may not be valid for exposure to radiu m beginning in the prenatal period. Should the findings be confirmed, consideration might be given to removing radium from drinking-water so urces.