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Use of a weight of evidence approach to determine the likelihood of adverse effects on human health from the presence of uranium facilities in Port Hope, Ontario

Abstract of the journal article published in the Journal of Environmental Protection (November 2011)

Prepared by:
Patsy Thompson
Canadian Nuclear Safety Commission (CNSC)


The radium and uranium processing industry exists in Port Hope, Ontario since 1932.  Between 1932 and 1966, most of the waste material from these industries was deposited throughout the town. During these years, waste management practices did not prevent the spread of contamination.  Several environmental and health studies have been conducted to assess the potential contamination effects in the Port Hope Community over the last 70 years.

The current study used a weight of evidence approach to assess the types and levels of contaminants of concern in the environment and the potential human exposure to these contaminants. Their toxicological and radio-toxicological properties were also assessed to determine their potential health effects. The results of these assessments were further compared to findings of earlier epidemiological studies of Port Hope residents and nuclear industry workers. The conclusions of this study indicated the following:

  • Levels of exposure to radioactive and non-radioactive contaminants in Port Hope are below levels known to cause adverse health effects.
  • Epidemiological studies provide no evidence of health effects as a result of past and present activities of the Port Hope nuclear industries.
  • The environmental risk assessments and the epidemiological studies are consistent and support each other.
  • Port Hope's findings are consistent with the results of over 40 epidemiological studies conducted elsewhere on populations living around similar facilities or exposed to similar environmental contaminants.

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