RISK OF CONGENITAL-ANOMALIES IN CHILDREN OF PARENTS OCCUPATIONALLY EXPOSED TO LOW-LEVEL IONIZING-RADIATION

Objectives-To evaluate the risk of having a child with a congenital an omaly in relation to occupational exposure to low level ionising radia tion in the pre-conception period. Methods-A case-control study based on the Canadian congenital anomalies registry used record Linkage tech niques to identify congenital anomalies among male and female workers in Canada's largest electric company. Cases were defined as parents of a child with a congenital anomaly born between April 1979 and Decembe r 1986 who had a congenital anomaly diagnosed within the first year of life. Controls were an individually matched sample of parents of a Li veborn child without an anomaly. Risk of congenital anomaly was assess ed in relation to parental exposure to ionising radiation acquired thr ough work within a nuclear generating station of an electric power com pany. Exposure was assessed according to employment, whether or not th e worker was monitored for radiation exposure, and quantitative estima tes of radiation dose. Results-Employment within the electric power in dustry was not associated with an increased risk of congenital anomali es in the offspring of mothers or fathers. Risk estimates for workers monitored (those who are likely to be exposed to ionising radiation) w ere 1.75 (95% confidence interval (95% CI) 0.86 to 3.55) for mothers a nd 0.84 (95% CI 0.68 to 1.05) for fathers. Exposure for fathers before conception, defined cumulatively and for six months before conception , was not associated with increased risk of anomalies in their offspri ng. There were no significant increases in risk found between type of anomaly and any measure of exposure, although the statistical power in these groups was limited. The study had insufficient numbers to evalu ate the effects of ionising radiation in mothers as only three mothers had recorded doses >0 mSv. Conclusions-Overall, workers in a nuclear power industry, and specifically those exposed before conception to lo w levels of ionising radiation, do not appear to be at an increased ri sk of having a liveborn child with a congenital anomaly.