RIVM Report 2016-0162
Within current risk assessment practices of chemicals, safe production and use for humans and the environment is most often evaluated per-chemical. However, in the environment there are always multiple chemicals simultaneously present. It is therefore of importance to assess the combined effects of co-occurring chemicals. The European Commission concluded in 2009 that current risk assessment practices insufficiently consider these combined effects. In this thought starter, the RIVM proposes an approach to account for such effects in the environmental risk assessment of substances under the REACH Regulation.
It is proposed to introduce a data-driven Mixture Assessment Factor (MAF) when assessing the environmental risk of a single substance under REACH. This factor should account for the number of chemicals that may possibly co-occur after emission of the target substance to the environment and that may consequently contribute to the combined effect. In this way is intended to ensure that, after emission to the environment, the substance together with all other chemicals present causes no combined environmental risk. In addition to this generic EU-wide approach, there is the possibility to consider further protective and curative measures on a site-specific basis when needed.
The approach proposed here as a thought starter is not new and has been employed in the Netherlands for quite some time in the derivation of negligible risk levels for the environment. The eventual quantification of the MAF under REACH requires further work with regard to the identification of (the number of) chemicals that contribute most to the overall EU-wide combined effects. An important aspect in this regard is to establish an acceptable protection-level to safeguard the nontoxic environment with regard to combined effects of chemicals. Also important is to determine to what extent combined effects of chemicals should be addressed via a generic approach at EU-level or whether it might be more