An Index of Harm for Exposure to a Combination of Radiation and Chemical Pollutants. S. B. Curtis, Fred Hutchinson Cancer Research Center, Seattle, WA; S. M. Bartell and E. M. Faustman, Department of Environmental Health, University of Washington, Seattle, WA; and W. C. Griffith, Consortium for Risk Evaluation with Stakeholder Participation, University of Washington, Seattle, WA
In order to provide a quantitative assessment of risk to individuals or to a population exposed to environmental pollutants, it is important to consider the effects not only from each individual pollutant, but from the combination of all pollutants. Each pollutant affects different organs with varying degrees of severity, thus making it difficult to arrive at an overall quantitative index of harm that weighs, in an appropriate manner, the various types of disease. In order to address this question, we review an approach taken for radiation exposure by the International Commission on Radiological Protection (the "aggregated detriment") and suggest an extension to include exposure to chemical pollutants. As a first approximation, both radiation and chemical carcinogenic effects are assumed to act independently and to increase linearly with no threshold at low doses. The result is an overall index of harm from exposure to both radiation and carcinogenic chemicals, which we call the combined aggregated detriment. The detriment accounts for four components of harm: the risk of fatal cancer in all relevant organs, the expected years of life lost due to specific tumor types, the risk of morbidity from induced non-fatal cancers, and the risk of serious hereditary disease in descendants of the exposed individual. An example is presented using combined exposure to benzene and radiation at relevant occupational and public health standards.
Supported (not endorsed) by CRESP by Department of Energy Cooperative Agreement #DE-FCO1-95EW55084.
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