Public health and public law issues for the toxicological risk assessment of chemical mixtures

Humans are simultaneously exposed to a near-infinite number of substances of both nutritional and toxicological interest. While traditional risk assessment has been based on the evaluation of effects of single substances, real-life exposure is characterized by their combination into chemical mixtures. As consequence, the need to focus on substance interactions is of considerable relevance. From the public health point of view, factors able to modulate the kinetic and toxicity of chemicals need to be included in the assessment of health effects. Several European projects including SOLUTIONS, EuroMix, ECD-MixRisk and HBM4EU have been implemented aiming at the characterization of hazardous properties of chemical mixtures and the development of new approaches and tools for their risk assessment, including advanced statistical methodologies. From the public law point of view, the legislative status of mixtures is outlined in a still general way, with a specific focus on a few substances only, e.g. dietary exposure to pesticide residues. Although some advances have been made with the ongoing revision of CLP Regulation specifically focusing also on chemical mixtures, identification of mixtures and the regulation of their use raise relevant and challenging issues to be timely addressed within a collaboration of specialists from toxicology, public health, and public law. Moreover, given the transnational scope of the problem, risk assessment of chemical mixtures presents a valuable occasion for a comparative law approach.