Stillbirths among offspring of male radiation workers at Sellafield nuclear reprocessing plant Original Research Article

Background Ionising radiation is a known mutagen, but few studies have examined transgenerational effects of paternal exposure in human beings. The workforce at the Sellafield nuclear reprocessing plant in the county of Cumbria, UK, is the most highly exposed workforce in western Europe and North America. This study, which is part of a larger programme of work investigating the health of the children of the Sellafield workforce, set out to find whether there was evidence of an association between stillbirth risk and paternal exposure to ionising radiation. Methods We collected details from birth registration documents for all singleton 248097 livebirths and 3715 stillbirths in the county of Cumbria 1950–89. Within this cohort the 130 stillbirths and 9078 livebirths to partners of male radiation workers employed at Sellafield were identified. Logistic regression was used to analyse the relation between stillbirth risk and fatherʹs preconceptional radiation exposure, with adjustment for social class, year of birth, fatherʹs age, and birth order. Findings A significant positive association was found between the risk of a baby being stillborn and the fatherʹs total exposure to external ionising radiation before conception (adjusted odds ratio per 100 mSv 1·24 [95% Cl 1·04–1·45], p=0·009). The risk was higher for stillbirths with congenital anomaly and was highest for the nine stillbirths with neural-tube defects. The statistical models predicted that, were the association to be interpreted as causal, between 0 and 31·9 of the 130 stillbirths to the workforce may be attributable to fatherʹs radiation exposure. Interpretation The findings of an increased risk of stillbirth with increasing paternal occupational exposure to external radiation are qualitatively consistent with those from animal models, though the risk estimate is higher. Although we cannot exclude the possibility of an unmeasured risk factor for stillbirth, confounded with paternal preconceptional irradiation, extensive checks confirmed that the statistical models were a good fit to the data and there was not statistical evidence of unmeasured factors.