Linear regulators general considerations

U.S. regulations for environmental contaminants have generally fallen in the 10-4 to 10-6 lifetime risk range, as calculated from a relatively worst-case linear multistage model. Most of those decisions incorporated consideration of costs and feasibility. 

There is considerable controversy over the shape of the dose-response curve at the chronic low dose levels important for environmental contamination. Proposed models include linear models, nonlinear (quadratic) models, and threshold models. Because risks at low dose must be extrapolated from available data at high doses, the shape of the dose-response curve has important implications for the environmental regulations used to protect the general public. Detailed description of dosimetry models can be found in Cember (1996), BEIR IV (1988), and Harley (2001). 

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