Hormesis: the new approach in risk assessment?

Hormesis is a dose-response phenomenon characterized by either a U-shaped or an inverted U-shaped dose response depending on the different end points measured. In a paper in this issue of the journal, Drs Jayjock and Lewis advocate for the application of hormesis in the field of industrial hygiene, and suggest the use of hormesis as a default assumption in the risk assessment process. However, there are many difficulties for the utilization of hormesis in the field of industrial hygiene. Indeed, it is impossible to test the hormesis hypothesis in many commonly employed experimental model systems for end points of public health concern, and the mechanism of low-dose stimulation of hormesis is not clear. Even if hormesis were proven biologically, its assessment is limited due to difficulties of study design, biological markers selection, statistical power considerations, model and end point selection, and risk model approaches.