Statistical Aspects of Chemical Mixtures

This paper reviews the considerable statistical research that has been performed in an attempt to characterize the joint action of two or more chemicals from both a statistical modelling and an underlying biological mechanism point of view. Particular attention is paid to the traditional descriptions of joint toxic action, i.e. independent joint action, similar joint action, and synergistic action. The more generalized biological classification developed by Hewlett and Plackett and by Ashford and Cobby are also considered. When chemicals are not interactive but affect similar sites, it seems that some knowledge of the likely toxicity of a mixture can be gained from the individual toxicities of its constituents. However, more biologically complex situations clearly require an understanding of the toxic mechanisms of the mixture before such projections can be made with any degree of confidence.