ChemRegs Newsletter – August 2022

Chief Scientist’s Group Report on mixture assessment in UK REACH

A joint report by the Environment Agency and the UK Health Security Agency has just been published, titled ‘Evaluation of the potential approaches to risk assessment of unintentional chemical mixtures for future UK REACH assessments’.

This project was published by the Environment Agency’s Chief Scientist’s Group, which provides scientific knowledge, tools and techniques to the UK government to help protect and manage the environment.

The European Council paper ‘Sustainable Chemicals Policy Strategy of the Union’, adopted by EU Member States (including the UK) in June 2019, committed the European Commission to address combination effects of chemicals. It is therefore necessary to determine the level of risk from unintentional mixtures of chemicals to ensure that any additional risk management measures are sufficient to provide protection.

The Chief Scientist’s Group Report focusses on the scientific considerations of how the potential risk from unintentional mixtures could be addressed under UK REACH. It identifies a recommended approach to address these risks to both the environment and human health. This will be important in informing future updates to UK REACH and whether changes should be made to the current risk assessment approach.

A brief summary is given below.

Background
There is international agreement that exposure to mixtures of chemicals has the potential to result in adverse effects in both people and the environment, even where individually the chemicals are below concentrations of concern. This can be the result of additive effects, i.e the so-called ‘cocktail effect’.

However, the current risk assessment approach under UK REACH considers chemicals in isolation as it only applies to the manufacture and use of single registered substances.

The UK therefore wanted to consider how the potential risk from unintentional mixtures (as may be formed following release of the registered substance into the environment) could be incorporated into the risk assessment approach for industrial chemicals.

Approach
The different methods available to estimate mixture risk were summarised, and the group reviewed studies that have estimated potential mixture toxicity based on measured chemical concentrations. The benefits and disadvantages of different methods that can be used to assess the risks from unintentional mixtures were considered.

Results
It was found that it is practically impossible to identify in advance which specific substances have the potential to contribute most to mixture risk, as this varies depending on the specific sites, time points and populations investigated.

Due to this, it was concluded that the application of a Mixture Assessment Factor (MAF) in risk assessment calculations is a pragmatic way forward. A MAF is an additional “safety factor”, which can either be used to derive ‘acceptable’ thresholds based on (eco)toxicity data or applied to the risk characterisation ratio (where a predicted or measured exposure concentration is divided by the acceptable threshold concentration). Either way, it would make risk assessment more conservative as it adds an additional layer of precaution.

Alternative approaches to a MAF require further data and resource before they can be applied, and the use of a MAF would retain the principle that it is the responsibility of the UK REACH Registrant to demonstrate that risks are adequately controlled.

With regard to the environment, a MAF of 5 appears to be appropriate and protective for most surface waters.

However, it was not considered appropriate to apply a MAF for human health at this time.

UK vs EU
This conclusion differs from the approach under consideration in the EU as part of the revision of EU REACH.

The European Commission has committed to address the combined effect of chemical mixtures by the implementation of a MAF in REACH. Several discussions have been held by the Competent Authorities for REACH and CLP (CARACAL) on how to best implement the MAF, and the EU Commission has also conducted a stakeholder consultation.

Support seems to be focussed on the implementation of a single generic MAF for both human health and the environment via Annex I of REACH. This will introduce a MAF in EU REACH on the Chemical Safety Assessments required in registrations of hazardous substances manufactured or imported in quantities greater than 10 tonnes per year.

Echa has estimated that 20% of substances registered under REACH could be impacted by the introduction of a MAF. This could cause nominal risk values to rise during risk assessment of substances and could increase costs for industry and potentially lead to some substances or uses being removed from the market. Echa presented the estimate during a workshop in April organised by Wood, a consultancy group that is assisting the European Commission on the best way to introduce a MAF under REACH.

A study commissioned by the European Chemical Industry Council (Cefic) concluded that a broad-brush approach such as one generic MAF that applied to all chemicals may not be the right solution. The findings of the study indicated 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.

The final outcome of the approach to be adopted in EU REACH is expected by the end of 2022.

EU CLP Poison Centre News

Iceland has now joined the majority of EU and EEA Member States in accepting poison centre notifications through ECHA’s submission portal. Bulgaria and Slovakia currently remain unconnected to ECHA’s systems, but they are working through the onboarding procedure.

The UK arrangements for accepting poison centre notifications are still under review (see our July Newsletter).

For more information on anything in this Newsletter, please contact us at info@chemregs.co.uk