High Cancer Rate Found in Offspring of Sellafield Fathers
by William Keepin, Ph.D.
First appeared in Nuclear Guardianship Forum, #3, Spring 1994.
Adults who work in facilities that handle plutonium and other radioactive materials may unwittingly pass on cancer to their future children. This is the implication of a detailed scientific study recently carried out by British epidemiologist Martin Gardner and his colleagues, to examine anecdotal reports that cancer rates are excessively high for children who live near the Sellafield plutonium reprocessing plant in Great Britain. (1)
The Sellafield plant is one of the principal sources of plutonium bound for Japan in numerous shipments planned over the next few decades. The first of these shipments has already arrived in Japan. Gardner and his colleagues concluded that the increased incidence of leukemia and non-Hodgkin's lymphoma among children in the vicinity of Sellafield is correlated with paternal employment at the plant. The results indicated that a father's exposure to routine low-level radiation on the job at Sellafield increases six- to eight-fold his children's risk of contracting leukemia or lymphoma. The Gardner findings are unprecedented, because they suggest that exposure to very low levels of radiation - well within accepted safety standards - may be sufficient to induce cancer in offspring.
Not surprisingly, the Gardner study has been highly controversial. The nuclear industry maintains that Gardner's contention is impossible because there are no known biological mechanisms for it, and because it is not observed in the data from survivors of the nuclear attacks on Hiroshima and Nagasaki. (Conventional wisdom on radiation safety relies heavily on the epidemiological data obtained from the aftermaths of attacks on Hiroshima and Nagasaki.) However, numerous radiation health experts believe that Gardner's results constitute a crucial new discovery of the potentially devastating effects of long-term exposure to low levels of radiation. They argue that there are several biological reasons why Gardner's results would not be observed among the survivors of Hiroshima and Nagasaki. For example, the bomb survivors received only a single dose at the time of explosion, whereas the Sellafield workers are subjected to continual low-level exposure over a long period of time. Also, the type of radiation in the two cases was different, and furthermore, most of the parental subjects in the bomb data were pre-pubescent children when exposed, whereas the Sellafield workers were sexually mature adults.
A lawsuit has been brought against British Nuclear Fuels PLC (the operator of Sellafield) by two plaintiffs who lived near the plant and contracted cancer (Elizabeth Reay and Vivian Hope). This suit is currently being heard in the Royal Court of Justice in London.
"...a father's exposure to routine low-level radiation on the job at Sellafield increases his children's risk of contracting leukemia or lymphoma by six to eight fold."
Dr. Scott Davis of the Fred Hutchinson Cancer Research Center in Seattle, Washington, provided crucial testimony at the London hearing. Davis is director of the large-scale Hanford Thyroid Disease Study authorized by the U. S. Congress and funded through the federal Centers for Disease Control. Davis is widely regarded as one of the most objective unbiased epidemiologists studying the effects of ionizing radiation. His reputation stems from the fact that the statistical conclusions from his previous research projects have in some cases lent support to environmentalists' concerns about radiation safety, and in other cases supported the nuclear industry's sanguine position.
Davis performed an exhaustive review of the voluminous literature relevant to Gardner's findings to determine whether Gardner's results were supported or refuted by relevant studies conducted elsewhere.(2) He reviewed 32 technical studies and analyses that were undertaken to determine whether or not there is a link between parental radiation exposure and childhood cancer. Of these, he examined in great detail the 13 most significant studies, seven of which supported such a link, and six of which did not. Beyond this work, Davis also reviewed 65 studies on the occurrence of cancer and other diseases around nuclear facilities in the United Kingdom, United States, and several other countries. The quality of each of these studies was assessed according to several criteria, including the type and quality of data, the soundness of the methodologies employed, and the statistical power of the results. The purpose of the review was two-fold: first, to determine if the excess cancers reported near Sellafield were an isolated phenomenon or if excesses of similar diseases have been seen in the vicinity of nuclear plants elsewhere; and second, to determine if the Gardner results were an artifact of the study design, the result of chance, or a real effect of potential biological importance.
Davis presented his findings in testimony at the hearing in London, England, on December 7 and 9, 1992. Based on his review of 65 studies of the incidence of cancer near nuclear facilities in various countries, he concluded that the weight of the evidence is consistent with an increase in leukemia risk associated with proximity to or probability of exposure from nuclear facilities. He testified that the excess cancers around Sellafield are thus not an isolated occurrence, and are therefore unlikely to be due to chance. He also reported that the Gardner study was methodologically and statistically sound according to nine key epidemiological criteria, and that Gardner's results provide the strongest evidence of a potential causal mechanism that could have brought about the excess cancers near Sellafield.
Davis further testified that the weight of the evidence among the 13 studies on the Gardner hypothesis supports a link between parental radiation exposure and childhood cancer. Among the six studies that reported no such link, he found no convincing evidence to refute the findings of Gardner. Three of these studies were so seriously flawed as to provide little information; two were so weak statistically as to be inconclusive; and the exposure characteristics in the sixth study were so unique that they could not be generalized in any sense. In contrast, the seven studies supporting the Gardner hypothesis were generally based upon better quality information regarding exposure and dosimetry; several provided evidence of a dose-response relationship, which in some cases was pinpointed to temporal intervals near the time of conception; and three of these studies appeared to be free of any substantial methodological flaws. Davis concluded that on balance, it is likely that the Sellafield workers' exposure to radiation contributed to the excess leukemias and non-Hodgkin's lymphomas in their children.
COMMENTARY
Martin Gardner and his colleagues have advanced the hypothesis, based on epidemiological evidence, that the risk of cancer developing in children of parents who work at the Sellafield plutonium reprocessing plant is six to eight times higher than normal. This hypothesis has been subjected to an unusually high degree of critical review in the form of numerous studies undertaken to explore this phenomenon further, as well as the exhaustive review carried out by Davis. The results of this review suggest that Gardner's hypothesis holds up under the most rigorous scrutiny and must therefore be taken seriously.
Not only might far more stringent radiation standards need to be enacted, but our entire understanding of the harmful biological effects of ionizing radiation may have to be radically revised.
The implications of Gardner's hypothesis are potentially quite profound. If it is true that workers' exposure to routine low levels of radiation can significantly increase the risk of cancer in their offspring, this will likely open up an altogether new domain of concern about radiation health safety, because the minuscule doses involved were previously deemed quite safe. Not only might far more stringent radiation standards need to be enacted, but our entire understanding of the harmful biological effects of ionizing radiation may have to be radically revised and expanded to account for these new low-dose effects. Moreover, meeting extremely strict radiation standards in industrial operations may be very difficult to achieve in practice. These developments would likely constitute yet another significant blow to the nuclear power industry, and would probably drive up the cost of nuclear power considerably at a time when the nuclear industry is already weak from a lack of economic competitiveness. Hence, the Gardner findings could serve to accelerate the decline of the nuclear power era.
Meanwhile, what of the thousands of workers in nuclear plants who now must wonder if their children will soon develop cancer? Or whether they should dare to have children at all? Or those whose children already have cancer?
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(1) M. J. Gardner et al., "Results of Case-Control Study of Leukaemia and Lymphoma among Young People Near Sellafield Nuclear Plant in West Cumbris," and "Methods and Basic Data of Case-control Study of Leukaemia and Lymphoma among Young People Near Sellafield Nuclear Plant in West Cumbris," British Medical Journal, February 17, 1990.
(2) Davis, Report into the Incidence of Leukaemia Around Nuclear Plants and Preconception Exposure to Radiation and Childhood Cancer (unpublished report for Plaintiffs), and testimony in Reay and Hope versus British Nuclear Fuels PLC, London, December 7-8, 1992.
William Keepin, PhD, is a consultant for the Energy Foundation, and a former researcher at the Rocky Mountain Institute.
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