United Kingdom Male workers at nuclear plants should not be concerned that exposure to radiation increases their risk of fathering still-born children, unless they have received a lifetime dose greater than 400 mSv. This is the primary conclusion of an epidemiological study published in the British medical journal The Lancet.
The study examined all births in Cumbria between 1950 and 1989 and compared the ratio of live to stillbirths in the county in general with those whose fathers worked at the Sellafield reprocessing plant.
“Statistical evidence shows a gradual increase in risk up to 400 mSv. Beyond that the risk appears to increase more rapidly,” said Louise Parker, one of the study authors. “At 100 mSv there is a 30% increase in risk, at 500 mSv there is a three fold risk and at 900 mSv the risk is nine times normal.” The paper’s authors emphasised that they have found a statistical association, and not established cause and effect.
According to Parker, since 1940 1600 men working at Sellafield have received more than 100 mSv of radiation before fathering children; none of the current workforce below the age of 35 has received a dose greater than 400 mSv.
BNFL, which runs the Sellafield plant, welcomed the study, saying that the results show that workers at the plant have nothing to worry about and that no worker should change any plans to have a family as a result.
“In interpreting these results we have to remember that we are talking about the statistics of very small numbers,” said David Coulston, director of environment, health and safety at Sellafield.
“For example, the statistical association which the study reports actually disappears altogether if just one single stillbirth case is removed. The findings themselves could also be interpreted as arguing against any real effect for radiation.” The idea that a father’s radiation exposure, particularly in the 90 days before conception, could have an impact on a child’s health was first raised in 1990 by Martin Gardner and colleagues. They suggested a link between exposure and leukaemia, a proposal which received widespread publicity at the time. Subsequent studies failed to support the link with leukaemia.
“The possible increases in risk associated with preconceptional exposure reported today do not bring the risk for stillbirth up to that faced by couples conceiving a decade earlier,” says a Lancet editorial accompanying the paper. “It is worth noting that the odds ratios reported by Parker and colleagues for stillbirth are much lower than that reported by Gardner and colleagues for leukaemia.” • The UK Government has announced a consultation process in response to a House of Lords report on the management of nuclear waste (See NEI April, p7). Major issues include the policy of substitution, whereby BNFL can return to reprocessing customers such as Germany and Japan, the same amount of radioactivity as received in the spent fuel, but in a concentrated form, leaving associated low and intermediate level wastes to be disposed of in the UK. Environmental groups have attacked this proposal arguing that it is driven by the government’s desire to partially privatise BNFL. BNFL points out that the policy is already in place and that it allows for significant savings in transport costs.
“The important issue is that we find a final solution for nuclear waste, not the total volume of waste involved,” said BNFL spokesman Alan Hughes. “Substitution offers significant benefits in terms of overseas trade, offering a better overall package for customers.”