EU REACH Mixture Assessment Factor

Cefic supports targeted application of the European Commission’s Mixture Assessment Factor


Mixture Assessment Factor

What is the purpose of the Mixture Assessment Factor?

According to the Chemical Strategy for Sustainability, the European Commission plans to introduce legal requirements to address the issue of “combined exposure to chemicals” meaning exposure to unintentional mixtures of different chemicals in the environment. A so-called “Mixture Assessment Factor” (MAF) would be applied to all chemical risk assessments to ensure that these unintended mixtures remain safe for people and the environment.

Latest research suggests a way forward

Over the past decade, at lot of research has been carried out towards gaining a better understand the issue of combined exposure. One of the latest and most comprehensive research in this field, conducted by Arche Consulting, made a detailed review of monitored mixtures of chemical in surface waters (the study was commissioned by Cefic). The study concludes that a broad-brush approach such as one generic MAF that applied to all chemicals may not be the right solution.

The findings indicate that:

  • approximately 90% of all monitored unintended unintentional mixtures of chemicals present no concern
  • Approximately 5% of the cases which pose some concern are already tackled by the existing legislative framework, for instance, a substance that poses concerns is already subject to authorisation, or is put on the prioritisation list of the Waste Framework Directive etc.
  • Around 5% of identified mixtures may pose concern which are outside of the current legislative framework. Any future regulatory requirements should target the relatively few chemicals typically appearing to dominate identified cumulative risks.

At the same time, a data review conducted by the Flemish Institute for Technological Research (VITO) indicates that the current data and evidence of the mixture exposure on human health are inconclusive, which makes it very challenging to develop refined concepts for assessing the risk of combined exposure to humans.

Cefic supports targeted application of MAF

Based on the results of this research, Cefic is working on a “decision tree” to help decision making assess whether a MAF needs to be applied for a specific substance when running an environmental risk assessment.

Disclamer: the version of a decision tree below is subject to further discussions and change

This decision tree can be easily integrated into the current regulatory framework.

The size of the applied MAF must be underpinned by data. Different methods have been reviewed to derive assessment factors using surface water monitoring data showing that the so-called ‘Maximum Cumulative Ratio’ (MCR) developed by Cefic-LRI which is by far the most robust method.

Cefic will continue engaging with the European institutions and ECHA to further elaborate on the best way to introduce MAF into existing EU chemicals safety legislation.