Chemical and radiation environmental risk management: Differences, commonalities, and challenges

Driven by differing statutory mandates and programmatic separation of regul atory responsibilities between federal, state, and tribal agencies, distinc t chemical and radiation risk management strategies have evolved. In the he ld this separation poses real challenges since many of the major environmen tal risk management decisions we face today require the evaluation of both types of risks. Over the last decade, federal, state, and tribal agencies h ave continued to discuss their different approaches and explore areas where their activities could be harmonized. The current framework for managing p ublic exposures to chemical carcinogens has been referred to as a "bottom u p approach." Risk between 10(-4) and 10(-6) is established as an upper boun d goal. In contrast, a "top down" approach that sets an upper bound dose li mit and couples with site specific As Low As Reasonably Achievable Principl e (ALARA), is in place to manage individual exposure to radiation. While ra diation risk are typically managed on a cumulative basis, exposure to chemi cals is generally managed on a chemical-by-chemical, medium-by-medium basis . There are also differences in the nature and size of sites where chemical and radiation contamination is found. Such differences result in divergent management concerns. In spite of these differences, there are several comm on and practical concerns among radiation and chemical risk managers. They include 1) the issue of cost for site redevelopment and long-term stewardsh ip, 2) public acceptance and involvement, and 3) the need for flexible risk management framework to address the first two issues. This article attempt s to synthesize key differences, opportunities for harmonization, and chall enges ahead.