Metabolic interactions of environmental toxicants in humans.

A description of the interactions between environmental toxicants following simultaneous exposure or exposure in close temporal sequence is presented. At the metabolic level, such interactions may be based on induction, inhibition, or activation of xenobiotic-metabolizing enzymes. Cytotoxicity may also play a role, particularly in affecting induction of xenobiotic-metabolizing enzymes. The effects of interactions manifested at the level of the expression of toxic endpoints may result from interactions at the metabolic level or may have other causes. New approaches to genome-wide effects (e.g., microarray studies) are also discussed.