Risk assessment is the standard method for evaluating exposure to toxic chemicals, despite the fact that it’s nearly impossible to do a risk assessment that is objective and accurate. There are just too many hard-to-meas
ure factors affecting the chance that any one chemical will harm us and if so, how and to what extent, and too many ways for personal bias to change the results. For example, there’s been a long argument about whether arsenic causes cancer. We do know that it’s poisonous. It probably does cause cancer, but many people seem to be immune. So we’re not sure how many cases might occur, and what amount of arsenic might cause cancer. Also, it doesn’t seem to cause cancer in animals, so there’s no way to put the information together. When there are information gaps, the only thing we can do is build-in an extra safely factor, by making the “allowable” level a certain amount less than what we think the “safe” level is. But is that really the answer?
The public wants greater protection from exposure to toxic chemicals than provided by the traditional quantitative risk assessment approach which has many limitations and uncertainties. Instead, support has grown for use of a precautionary approach that promotes (1) preventive action, (2) democratic and transparent decision-making with the broadest possible public participation, and (3) a shifting of the questions being asked (e.g., instead of asking what level of risk is acceptable, asking how much risk can be avoided; what is the need; why is it needed; who benefits and who is harmed; and what are the alternatives?) as well as the presumptions used in decision-making (e.g., shifting the burden of proof to the proponents of potentially harmful activities, and placing public health above other considerations).
In its 2009 report, Science and Decisions, the National Resource Council (NRC) of the National Academies acknowledged that risk assessment is “at a crossroads” facing “a number of substantial challenges”, that “its credibility is being challenged”, and that the “regulatory risk assessment process is bogged down”. The report made a number of recommendations that focused on improving the methodology of risk assessments (e.g., thorough evaluation of uncertainties and variability, unified dose-response approach to cancer and non-cancer endpoints, broadening the assessment of cumulative and interacting health risks and stressors), and improving the relevance or utility of risk assessments for decision-making (e.g., involving all stakeholders at the earliest stage of the planning, design and scoping of the risk assessment, and increasing the transparency of the assessment methods and process).
The NRC recommended two major shifts: (1) “that risk assessment should be viewed as a method for evaluating the relative merits of various options for managing risk”, with the risk management questions being “clearly posed, through careful evaluation of the options available to manage environmental problems at hand,” casting light on “a wider range of decision options than has traditionally been the case”; and (2) aligning closely the technical analysis with the problem at hand so that the risk assessment will be relevant to the needs of the decision-makers and stakeholders who are addressing the problem (e.g., a “one size fits all” approach to risk assessment will not be appropriate for such very different problems as regulating a chemical and deciding on a site remediation approach).
These recommendations are now more than 5 years old, and there’s little evidence that government is adopting these recommendations. Doing so should improve the ability to interpret hazards, contamination levels and population exposures, dose-response relationships, and cumulative risks (exposures from multiple pathways, complex mixtures, multiple stressors, and factors affecting vulnerability), as well as the evaluation of a wide range of alternative options (e.g., inherently safer technologies, alternative ways to achieve the same goal, etc.). It could also provide a way to integrate the risk assessment tool within a broader precautionary approach that seeks to reduce or avoid exposures to toxic chemicals, which the public is actively calling for. It’s time to stop accepting risk assessment as the best we can do to evaluate risks and adopt more a holistic approach to protecting public health and the environment.