Human health risk assessment: a historical overview and alternative paths forward

Risk assessment has become a more structured activity during the past 50 years and increasingly is being used to inform major policy decisions. Much use has been made of the hazard identification phase of risk assessment to identify potentially hazardous materials or situations and guide actions to minimize potential risks. Much less frequently the process has been carried further, with estimates developed of the potency of the hazardous agent for causing adverse effects. And even less frequently, robust estimates of exposure have been developed. Thus, in only a few instances have risks been fully characterized in quantitative terms for either individuals or populations. To develop scientifically valid risk characterizations for many chemicals, much more scientific information must be acquired in a targeted manner to establish the potency of chemicals for causing cancer or other adverse health effects. Similar substantial effort must also be applied to characterizing the exposure populations receive from specific chemicals released from various source categories. In the absence of these scientifically rigorous approaches it is likely that societal actions will be guided primarily by identification of potential hazardous agents, with attempts made to minimize the hazard by banning or restricting use of the agent. This precautionary approach may not yield the maximum reduction in health risks to society for the investments made and, in addition, may deny society access to materials or processes that under appropriate conditions of use would not result in significant health risks and may indeed, have substantial net benefits to society.