The hormesis concept and risk assessment: are there unique ethical and policy considerations?

The hormesis concept holds that low doses of toxic substances and radiation elicit modest biological responses opposite to those caused by higher doses of the same agents. This concept stands in contrast to the prevailing views that a threshold model predicts most responses to toxicants at low doses and that linear extrapolation best predicts mutagenic and carcinogenic responses. Beyond the scientific considerations, there has been concern that inclusion of the hormesis model in risk assessment would raise complex ethical questions, pose serious challenges for policy makers, and threaten public safety. This article briefly reviews the growing evidence for hormesis and offers a perspective on the related ethical and societal issues. Complexities stem from the nature of biphasic curves, in which biological responses fall both above and below background levels. The monotonic responses of the threshold and linear models lend themselves to a single policy objective--avoiding harm associated with exposures. The biphasic responses of the hormesis model, however, suggest the possibility of accruing benefit as well as avoiding harm. The prospect of applying the hormesis model to public health policy is impeded by insufficient ability to identify the hormetic and toxic zones with precision. Moreover, heterogeneity among individuals in susceptibility to toxicants suggests that benefit and risk may be distributed unequally in the population. The potential shift in policy objectives associated with hormesis is considered relative to the difficulty of balancing the ethical principles of nonmaleficence and beneficence while maintaining a higher priority on the former.

A perspective on the scientific, philosophical, and policy dimensions of hormesis

The hormesis concept has broad implications for biology and the biomedical sciences. This perspective on hormesis concentrates on toxicology and toxicological risk assessment and secondarily explores observations from other fields. It considers the varied manifestations of hormesis in the context of a broad family of biological stress responses. Evidence for hormesis is reviewed, and the hormesis model is contrasted with more widely accepted dose-response models in toxicology: a linear nonthreshold (LNT) model for mutagenesis and carcinogenesis, and a threshold model for most other toxicologic effects. Scientific, philosophical, and political objections to the hormesis concept are explored, and complications in the hormesis concept are analyzed. The review concludes with a perspective on the current state of hormesis and challenges that the hormesis model poses for risk assessment.

A case for deliberation in response to hormesis research

Research on the phenomenon of hormesis (i.e., low-dose stimulatory effects caused by normally inhibitory or toxic substances) has recently provoked a good deal of debate. Formal mechanisms for deliberation and public participation are increasingly popular strategies for responding to controversial decisions in environmental policy, but they have been used only to a limited extent in response to scientific research itself. This commentary introduces natural scientists to some of the social scientific literature on these issues and argues for the importance of “diagnosing” whether controversial areas of policy relevant research would benefit from some form of deliberation. It provides a tentative diagnosis in the case of hormesis research, recommending a varied deliberative approach. There are many reasons to pursue broadly based deliberation in response to hormesis, including the potential to promote more productive research projects, alleviate public distrust, and prevent bias. Deliberative proceedings in this case should address judgments associated with at least four activities: (1) choosing projects and designing studies, (2) developing terminology, (3) interpreting and evaluating studies, and (4) applying research results to public policy. Although an advisory group composed primarily of experts might provide an adequate starting point, more intensive deliberative processes would be valuable before developing major changes to regulatory policy.

Elliott's ethics of expertise proposal and application: a dangerous precedent

In a recent paper in Science and Engineering Ethics (SEE) Elliott proposed an ethics of expertise, providing its theoretical foundation along with its application in a case study devoted to the topic of hormesis. The application is based on a commentary in the journal Nature, and it includes assertions of ethical breaches. Elliott concludes that the authors of the commentary failed to promote the informed consent of decision makers by not providing representative information about alternative frequency estimates of hormesis in the literature, thereby hindering the capacity of the scientific community to promote informed consent relating to chemical regulation. This paper argues that Elliott should have incorporated due process into his system of evaluation. His argument is also seriously deficient technically, in that it misinterprets the toxicological issues, misrepresents the scientific literature with respect to the frequency of hormesis, and incorrectly assesses the extent to which the Nature paper revealed opposing/alternative views on hormesis. Given the seriousness of assertions of noncompliance to ethical norms, there must be procedures to protect those whose ethics were called into question, to fairly evaluate the technical justification for an assertion, and to enable corrections in the event of errors. If a journal is willing to publish assertions that individuals acted in an ethically questionable way, it should be guided by a documented code of ethics and meet a standard of responsibility far greater than normal peer-review processes for papers that do not entail such ethical judgments.

An ethics of expertise based on informed consent

Ethicists widely accept the notion that scientists have moral responsibilities to benefit society at large. The dissemination of scientific information to the public and its political representatives is central to many of the ways in which scientists serve society. Unfortunately, the task of providing information can often give rise to moral quandaries when scientific experts participate in politically charged debates over issues that are fraught with uncertainty. This paper develops a theoretical framework for an "ethics of expertise" (EOE) based on the notion that scientists have responsibilities to provide information in a way that promotes autonomous decision-making on the part of the public and its representatives. Moreover, insofar as the principle of informed consent has developed in biomedical ethics as a way for physicians to promote autonomous decision-making on the part of their patients, this paper suggests that the informed-consent concept may suggest a set of criteria and guidelines that can help scientists to fulfill their similar ethical responsibilities to the public. In order to illustrate how the resulting EOE could provide practical guidance for scientific experts, the paper examines a case study involving the dissemination of information about the low-dose biological effects of toxic chemicals and carcinogens.