This approach uses formal modeling techniques similar to those used in cancer risk assessment to develop quantitative dose-response relationships based on either human or animal studies. Thus, the benchmark dose approach differs from those used in cancer risk assessments in that the models developed are not used to extrapolate risks at very low dose levels. Thus, OSHA believes that the benchmark dose approach shows promise as a consistent and defensible method by which the Agency can establish reasonable exposure limits based on nonneoplastic health effects. As such, OSHA wishes to hear considerable discussion on the experience of those who are familiar with or who have used this method to evaluate public health risks, and what alternative approaches can be utilized that address issues raised by the Court ruling on the Air Contaminants standard. In particular, OSHA is interested in hearing discussion on how to best implement approaches to derive exposure limits from benchmark dose values, and how these methods can be interpreted in terms of the significance of the risk and the magnitude of risk reduction achieved.
Some risks are plainly acceptable and others are plainly unacceptable.
If, for example, the odds are one in a billion that a person will die from cancer by taking a drink of chlorinated water, the risk clearly could not be considered significant. OSHA would welcome comments that would enable it to shed light on the acceptability of risk levels within this million-fold range. OSHA has had less experience in evaluating significant risk for the broad range of other adverse health effects experienced by workers who are exposed to hazardous levels of chemical substances. References Crump, K.S. 1984. A new method for determining allowable daily intakes.