On November 27, 2020, news provider Chemical Watch reported on a review by researchers from Brunel University London and the European Commission’s Joint Research Centre (JRC) confirming that an additive approach is a “robust” way to describe chemical mixtures.
Previous systematic reviews looked only at a limited number of chemicals and types of toxicity. In the current review, the researchers analyzed experimental data from over 700 experimental mixture-related studies covering an inventory of 1220 experiments – the largest review of its kind to date. They could confirm that additivity concepts represent a good approximation of mixture effects. There was only a small portion of reviewed studies that showed synergistic toxicity effects, which according to the authors “did not stand up to scrutiny.”
The biggest issue revealed, according to the researchers, is the fact that most published studies have focused primarily on binary mixtures. Andreas Kortenkamp, lead author of the study criticized this commenting that “studying binary mixtures has its merits, but it is hard to understand why so few studies used more than two components.”
The authors further described the field of mixture assessment as still “overly descriptive, repetitive, and under-theorized” and needs to address “real-world challenges,” such as developing general mixture risk assessment methods and viable approaches to regulation.
In October 2020, the European Commission published its chemical strategy that recognizes a need “to apply practical and workable approaches to dealing with unintentional mixtures.” This would include the utility of a mixture assessment factor (MAF) for REACH as proposed by the Dutch and Swedish governments earlier this year (FPF reported).
Kortenkamp praised the strategy’s intention to deal with mixtures and that application of additive mixture models could be an important step towards “mixture assessments for regulatory practice.” In addition to this recent study, the research team has also published a review protocol.
Martin et al (January 2021). “Ten years of research on synergisms and antagonisms in chemical mixtures: A systematic review and quantitative reappraisal of mixture studies.” Environment International
Emma Davies (November 26, 2020). “Major European review confirms that additive approach works for chemical mixtures.” Chemical Watch
Andrew Turley (May 28, 2020). “Review suggests synergistic and antagonistic mixture effects are relatively rare.” Chemical Watch
Andrew Turley (March 12, 2020). “MAF advocates upbeat despite softened pledge in EU strategy.” Chemical Watch
Andrew Turley (December 10, 2020). “European Commission aiming to publish draft MAF roadmap by end of year.” Chemical Watch