Thirty-five institutes from 18 European countries have joined forces in PARC to improve mixture risk assessment using human biomonitoring (HBM) data.

This has resulted in PARC now proposing a strategy for mixture risk assessment using HBM data. The document aims to support regulatory risk assessment by providing methods, tools and concepts.  

Need for mixture assessment

Individuals are exposed to mixtures of chemicals daily via dietary intake and environmental exposure among others, which can potentially result in adverse health effects. Dietary risk assessment of chemical mixtures is now relatively well addressed by the European Food Safety Authority (EFSA) and pilot studies have been published on risk of combined dietary exposure to pesticides and PFAS.

The European Commission's Chemicals Strategy for Sustainability ↗ described the need for mixtures exposure assessment via all relevant routes of exposure including occupational exposure. This concern will be covered in next generation risk assessment using HBM data and this is now addressed in the PARC project “Real-life mixtures”.

The PARC project “Real-life mixtures” aims to consolidate on international guidance ↗ from EFSA and the OECD describing the relevance of scientific grouping of chemicals affecting a target organ or a specific function of a target organ for conducting human risk assessment of mixtures.

Furthermore, the PARC project consolidates on the recommendation and lessons learned ↗ from the EU funded HBM4EU project ↗. Complementary to and in synergy with current activities at the European Agencies, the project will develop practical tools, data, methods, and a general strategy to enable an effective mixture risk assessment based on HBM data.

Evaluating the risk of mixtures for end-user

The new PARC deliverable outlines the initial steps of the strategy developed in the first year of the PARC project “Real-life mixtures”. The proposed strategy to perform mixture risk assessment is based on knowledge developed for mixtures in regulatory risk assessment and in the field of toxicology, exposome and epidemiology.

HBM data from European studies have been listed in a data inventory. A process of harmonising the data from these partner studies has been initiated. Hazard data (including grouping into effect and toxicokinetic information) has started to be collected and organised. Statistical analysis (such as mixture identification) has been implemented in the Monte Carlo Risk Assessment (MCRA) toolbox and will be performed in a harmonised way in 2023/2024. Analysis is first carried out on prioritised chemical families (e.g. pesticides, heavy metals and PFAS) which are associated with specific health effects of concern (e.g. neurotoxicity, nephrotoxicity and immunotoxicity).

The PARC project “Real-life Mixtures” will propose a coherent implementation of the data and models for evaluating the risk of mixtures for end-users being EFSA panels/ ECHA working groups, national experts and other relevant stakeholders such as the chemical industry.