including how to incorporate concerns regarding potential additivity and interactions among the mixture components into the overall site assessment. The recommendations are based on the evaluation of the background information on the individual chemicals, presented in the Appendices, and the evaluation of mixtures and joint toxic action data performed in Chapter 2. The recommendations should be congruent with methods detailed in ATSDR (2001). Therefore, authors of interaction profiles must be thoroughly familiar with that guidance document and the methodologies described therein.