Under Task 9.3, EuroMix organised a series of four workshops on the international harmonisation of the risk assessment of combined exposure to multiple chemicals, with the aim of exploring options and potential limitations in the international acceptance of the approaches being developed by EuroMix. International acceptance has obvious implications for those commodities where Maximum Residue Limits (MRLs) have to be established for residues, in that if very different approaches were to be used for combined risk assessment, the acceptability of MRLs could vary markedly. This report describes the outcome of the four workshops and their recommendations.