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Tritium releases from Candu reactors: Health hazards of radiation

Nuclear Monitor Issue: 

(June 25, 1992) Two Canadian Government studies reveal that Down's Syndrome, central nervous system birth defects and child leukemia are likely caused by tritium emissions from Ontario Hydro's Pickering nuclear station.

(374/5.3679) WISE Amsterdam -

But, charges a report by David McArthur of Conception Research, the studies do not go far enough and their weak methodology may mask the full extent of the health hazards of radiation. New studies, says McArthur, are needed.

McArthur's report, "Birth Defects and Genetic Disease Due to Tritium Emissions from the Pickering Nuclear Station Suggested by Two AECB Health Studies", examines the findings of two studies commissioned by Canada's Atomic Energy Control Board (AECB): "Tritium Releases from the Pickering Nuclear Generating Station and Birth Defects and Infant Mortality in Nearby Communities 1971-1988" a 1991 report by Health and Welfare Canada (HWC), and "Childhood Leukemia Around Canadian Nuclear Facilities", a 1991 report by the Ontario Cancer Treatment and Research Foundation (OCTRF) and the University of British Columbia (UBC). McArthur, whose earlier report (#CR-1) led to the present HWC report, concludes that despite their denials, the epidemiological evidence presented in the AECB reports in fact indicates that radioactive emissions from the Pickering station are causing birth defects in local children. The HWC birth defect study correlates tritium emissions with two types of birth defects. Specifically:

  • HWC found a "statistically significant" increase in Down's syndrome in Pickering: 24 cases (12.9 expected after maternal age adjustment) or 87% above the provincial rate. HWC correlated these cases with tritium releases to the air from the plant. McArthur says that although this is not a statistically significant correlation, this needs further research. The elimination of methodological biases (described below) could strengthen the correlation.
  • This finding is crucial since Down's Syndrome in children has been associated with parental radiation exposure by researchers in Canada, the US, Ireland, Scotland, England, Denmark, Germany, Italy, and India. The sources were maternal x-rays, high background radiation, or radioactive fallout from the Chernobyl (1986) and Windscale (1957) nuclear accidents.
  • HWC found a "statistically significant" correlation of central nervous system (CNS) birth defects with large releases of tritium to air: five Pickering infants with CNS defects (anencephaly, microcephaly, spina bifida with hydrocephalus, and two others whose defect code was not on record) were born in January-July 1978, following the airborne tritium releases of April-October 1977. Medical experts link CNS birth defects to radiation exposure, as found after the atomic bombing of Japan.

These conclusions, says McArthur, emerge despite HWC's biases, which likely mask the full extent of the radiation-birth defect connection. Conception Research predicts this correlation will tighten if a new study is done without the eight biases McArthur lists in his report.

The other AECB study concerned leukemia. It found a "nearly statistically significant" 34% elevation in child leukemia deaths within a 25 km radius of the Pickering plant. In this report, too, McArthur identified a major bias. For one thing, he says, the 25 km radius was unjustifiably large - much larger than that used in leukemia studies in the US (3.2 km) and other countries. The report itself admitted that the radius is too large, and inappropriate for the suburban Pickering area. This would likely have masked a statistically significant cluster of child leukemia in Pickering.

The new Conception Research report also describes the major, unique health hazards of the Pickering station, which routinely emits large amounts of radioactive tritium and carbon-14. Evidence suggests, says McArthur, that these accumulate in human tissue and DNA and cause higher radiation doses to chromosomes than existing standards acknowledge, and more genetic damage than "background radiation" and other radiation sources.

In February, The Durham Regional Municipality requested the Canadian government to conduct an objective, in-depth study of reproductive health in Pickering as recommended by the HWC report. The AECB and HWC have thus far refused to perform the study.

Note: The full Conception Research report (Report #CR-3, June 1992), 25 pp., is available for CDN$30 (plus $5 shipping) from the address below. Also available from Conception Research is a bibliography, "Birth Defects and Radiation: Some Selected Publications".

Source and Contact: Conception Research, Postal Station "B", Box One, Toronto Ontario, Canada M5T 2T2; tel: +1 416-598 0146; fax: -928-0243; e-mail: WEB:DMCART.