Figures 1 and 2 present overviews of the strategies for exposure-based assessment of joint toxic action of chemical mixtures on noncarcinogenic and carcinogenic effects. Detailed discussions of these strategies are provided in ATSDR (2001). The figures show how interaction profiles, and the various methods for incorporating concerns regarding additivity and interactions, fit into the overall scheme for mixtures assessment at a site. The interaction profile makes recommendations regarding how to approach assessment of a particular mixture, but the actual site assessment will be performed by an environmental health scientist or toxicologist using site-specific exposure data in concert with the approach recommended in the interaction profile and with ATSDR (2001).