Economic implications of hormesis in policy making.

Economists face no fundamental problem in calculating the optimal exposure of a hormetic substance and this could potentially be set as a regulatory level. This level would be where the marginal cost of control is equal to the slope of the exposure-response function. There are a number of reasons, however, to expect public resistance to assuming hormesis. These reasons include the fact that hormesis implies a lower level or risk for any given exposure; it might be viewed as weakening regulatory standards; and it could justify low emissions if marginal costs are low. If all we care about are the negative effects measured by a single health endpoint, then the RfD (the level of exposure below which there is no appreciable risk) may be appropriate. Hormesis maintains the single endpoint, but accepts beneficial as well as deleterious effects. If we are going to accept beneficial effects then we should consider all health endpoints and all costs and benefits. This is simply benefit-cost analysis with a hormetic exposure-response curve. Because of legal constraints, this type of analysis may be of little use in setting tolerance levels, but may be important if the EPA chooses to adopt more voluntary policy measures.