Economic implications of hormesis.

The implications of hormesis for decision making about control of environmental exposures are examined. From an economic perspective, environmental exposures should be controlled to a level that optimizes health effects and minimizes control costs. The possibility that substances are, or may be, hormetic poses no fundamental challenge for economic analysis. In contrast with the linear no-threshold model, optimal control may be either less or more stringent under the hormetic model, depending on the incremental control cost. When exposure levels or exposure-response functions differ across individuals or are uncertain, the optimal population-level control of exposure must balance possible benefits and harms to individuals against control costs. Economic-incentive-based regulatory instruments, such as tradable permits, are likely to offer less improvement relative to command-and-control regulations under a hormetic model than under a linear no-threshold model.