CHEM Trust

Protecting humans and wildlife from harmful chemicals

Chemical mixtures

Blood vialsWhy are mixtures a problem?

Throughout our lives we are exposed to hundreds of chemicals from multiple sources, such as flame retardants in soft furnishings, phthalates in plastic packaging, or PFAS in cosmetics. However, current safety assessments primarily focus on single substances. This is a problem because we are not exposed to chemicals one at a time. Combined exposure to chemicals (a ‘mixture’ of chemicals) can lead to harmful effects, even if single substances in the mixture are below their individual safety levels. 

Scientific research has shown that mixtures are a real-world issue. For example, the EU Horizon 2020 EDC-MixRisk project looked at chemicals that could be found in the blood or urine of pregnant women in Sweden. Many of the chemicals identified were already known to be endocrine disrupting chemicals (EDCs) and associated with adverse health outcomes in children. The scientists then looked at a model mixture of these chemicals at concentrations similar to those found in the women. These mixtures were found to cause adverse effects and dysfunctions in these animal and cell models; such as changes in reproductive organs and brain development.

The environment – rivers, oceans and countryside – is also polluted by hundreds of different substances, including pesticides, plasticisers, flame retardants and pharmaceuticals. Current safety assessments of chemicals mainly focus on single substances, and thus current regulations on chemicals systematically underestimate the health and environmental risks associated with combined exposures.

Concern around mixture effects of chemicals is not new, but sufficient political action has not been taken

Discussions about the harm that mixtures of chemicals pose to humans and wildlife started over a decade ago:

  • In 2009, the European Council published conclusions on ‘Combination effects of chemicals’, inviting the Commission to further assess the topic.
  • In 2009, the report ‘State of the art of mixture toxicity’ recommended the development of guidelines for the assessment of chemical mixtures.
  • In 2013, the 7th Environmental Action Plan set out obligations for the EU to develop and implement approaches to address combination effects of chemicals by 2020 – these have not been met.

CHEM Trust has been calling for mixtures to be addressed in chemicals legislation for several years. In 2009 we advocated for considering cumulative effects of phthalates with additive effects under REACH following the landmark report by the US National Academies ‘Phthalates and Cumulative Risk Assessment‘ in 2008.

However, action on mixtures has been far too slow. The issue has been neglected by EU decision makers, and it is only in the past couple of years that the issue has begun to gain more attention.

Support for action on mixtures

In 2016, the Joint Research Centre of the EU Commission (JRC) published a ‘Review of case studies on the human and environment risk assessment of chemical mixtures’ which identified a series of data gaps and recommendations to fill these gaps.

In 2019, the European Food Safety Authority published guidance on harmonised methodologies for human health, animal health and ecological risk assessment of combined exposure to multiple chemicals.

Two recent EU projects have investigated the exposure to mixtures of EDCs. The EU Horizon 2020 EDC-MixRisk project investigated the effects caused by real-life relevant synthetic chemical mixtures. The overarching conclusion is that current regulation of synthetic chemicals systematically underestimates the health risks associated with combined exposures to EDCs or potential EDCs. The EuroMix project identified different methods and delivered a test strategy to generate missing hazard data, and invited policymakers and researchers to use the new approaches.

In 2019 the EU environment ministers called on the European Commission to introduce requirements to ensure that the mixture effects of chemicals are addressed in the risk assessment and risk management processes of relevant EU legislation.

Four phthalates (DEHP, DBP, DIBP and BBP) have been restricted under REACH based on their combined exposure. This is one of the first examples of a restriction of a group of chemicals based on their cumulative effects.

New signs of progress: Chemicals Strategy for Sustainability

The EU Chemicals Strategy for Sustainability advocates for the strengthening of the regulatory framework to increase the level of protection from combinations of chemicals including:

  • Assessing the introduction of a Mixture Assessment Factor in REACH (see more below)
  • Reinforcing measures to take account of combination effects in other laws, such as on food packaging, cosmetics and toys.

The release of the Strategy was also accompanied by an EU Commission Staff Working Document which summarises recent research and concludes that although knowledge gaps in the science are being filled, more effort is needed to address unintentional chemical mixtures.

Mixture Assessment Factor

A 2019 joint statement from the JRC and researchers from EDCMixRisk, EuroMix, EUToxRisk, HBM4EU and SOLUTIONS recommended the application of a Mixture Assessment Factor (MAF) as a way to decrease the total burden of exposure to chemical mixtures.

A Mixture Assessment Factor under REACH would provide an adjustment factor to use in the risk assessment of an individual chemical in order to reflect the potential for mixture effects. CHEM Trust and other NGOs support the proposal to introduce the MAF into Annex I of REACH, see joint position paper. CHEM Trust first advocated for an additional assessment factor to address combination effects in risk assessments almost a decade ago.

Read more about the MAF and ongoing policy developments in our blog post and in this presentation.

Further action also needed

The MAF approach by itself is not enough to ensure the protection of people and the environment from the combination effects of chemicals. In addition, the EU must:

  • Establish an overarching framework to consider mixtures in all relevant EU laws;
  • Move away from single substance risk assessment;
  • Use regulatory tools (such as REACH, pesticides and biocides laws) to reduce exposure to harmful substances in the general population.

CHEM Trust’s previous contributions on mixtures:

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