Issues in biochemical applications to risk assessment: how do we predict toxicity of complex mixtures?

used. Then the gravest and most sensitive effect is identified; that is, the effect which is thought to occur at the lowest level (for regulatory action). For example, TCDD is not only potent for carcinogenic effects, but also potent for reproductive effects. However, the acceptance of a low-dose linear nonthreshold response pattern for carcinogens has emphasized the carcinogenic effect of TCDD rather than the reproductive response. So this is one person's view of how one goes about predicting the toxicity of complex mixtures, namely, that there are two approaches: the first is where one identifies the risk from the individual components for which there is data and accumulates the risk. And the other is where the mixture is treated as a single agent and potency variations in composition are taken into consideration (1,2). And that ends my opening remarks. Anybody have comments or views to the contrary?