An opinion article published on December 7, 2018, by regulatory news provider Chemical Watch, discussed science on toxic effects of chemical mixtures and practical application for regulatory risk assessment of mixtures. Andreas Kortenkamp, professor of human toxicology at Brunel University in London, asserted that “the science [of mixture toxicity] is ready,” including “the theory of mixture toxicology” and “predicting combined effects.”

In 2009, Kortenkamp together with two other scientists published a report on mixture toxicity for the European Commission (EC). Already back then, there was “sufficient know-how to assess the risks that may result from the combined exposure of humans and the environment to multiple chemicals.” However, to enable implementation, there was a need for “consistent and clear mandates . . . for taking mixture toxicity into account in the numerous pieces of legislation.” This message remains “remarkably unchanged” almost a decade later (FPF reported), despite being supported by numerous international organizations as well as representatives of five recent EU projects that focus on chemical risks (FPF reported).

Industry, however, “has yet to be convinced about the need for change.” A position paper by industry association Cefic, released in September 2018, said that “current regulatory schemes are adequate for controlling the risks” of mixture toxicity. In contrast, Carl-Gustaf Bornehag, professor of public health sciences at Karlstad University, Sweden, thinks that “we have more and more evidence – not only from our data but also from other sources – that we do have mixture effects.” He is part of the EDC-MixRisk project that recently found that “single chemical assessments [for endocrine disrupting chemicals] could be underestimating the risk for mixtures one- to tenfold” (FPF reported).

The practical means of setting regulatory thresholds for single chemicals based on mixture toxicity risk have not been “cracked” yet. Furthermore, there is “acute need” for more data, especially on the exposure side. Kortenkamp, however, “believes this is not a good reason to delay change to the regulatory environment. The current situation is reminiscent of a “Catch 22-type dilemma: we cannot switch to a mixture-centric system of risk assessment because we do not have the data we would need for such a system, but we cannot get the data without switching to it.”

In addition, “the change could be made gradually, with an initial focus on integration of closely linked areas of regulation to improve consideration of mixtures.” For example, pesticides could be considered “as part of a mixture when assessing the risks form other potential food contaminants, such as migrants from food contact materials.” Further, as an intermediate measure, “policy makers could implement the mixture assessment factor (MAF) concept,” so Kortenkamp.

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Andrew Turley (December 7, 2018). “Applying science to mixtures.Chemical Watch

Chemical Watch (December 11, 2018). “Kortenkamp boosts calls for legal mandates for mixture risk assessment.