Mixtures of contaminants: can we assess the risks they pose?

Consumer exposure to contaminants is often due to complex mixtures of chemical agents. The assessment of cumulative risks to humans arising from simultaneous or sequential exposure to multiple chemical agents of various origins, entering the body via different routes, is generally not adequately taken into account by the competent authorities. Regulatory assessments of the toxicity of these mixtures (where the chemical agents are known and toxicological data are available) are essentially based on evaluating the safety of each component taken individually or on tests carried out on the mixture as a whole. Several teams at INRA, mainly in Toulouse, are currently testing mixtures of chemical compounds using in vitro and in vivo systems. They have developed innovative tools and approaches designed to characterise the additive, supra-additive or infra-additive effects of chemical substances in mixtures, as well as to gain a better understanding of human exposure to complex mixtures.