Chemical Mixtures in the EU Population: Composition and Potential Risks

Abstract

Regulating chemical mixtures is a complex scientific and policy task. The aim of this study was to investigate typical mixtures and their potential risks based on internal exposure levels in the European population. Based on human biomonitoring (HBM) data made available via the HBM4EU project, we derived generic mixtures representative of a median (P50) and a worst-case scenario (P95) for adults and children. We performed a mixture risk assessment based on HBM concentrations, health-based guidance values (HBGVs) as internal thresholds of concern, and the conservative assumption of concentration addition applied across different toxicological endpoints. Maximum cumulative ratios (MCRs) were calculated to characterize the mixture risk. The mixtures comprise 136 biomarkers for adults and 84 for children, although concentration levels could be quantified only for a fraction of these. Due to limited availability of HBGVs, the mixture risk was assessed for a subset of 20 substance-biomarker pairs for adults and 17 for children. The mixture hazard index ranged from 2.8 (P50, children) to 9.2 (P95, adults). Six to seven substances contributed to over 95% of the total risk. MCR values ranged between 2.6 and 5.5, which is in a similar range as in previous studies based on human external exposures assessments. The limited coverage of substances included in the calculations and the application of a hazard index across toxicological endpoints argue for caution in the interpretation of the results. Nonetheless the analyses of MCR and MAFceiling can help inform a possible mixture assessment factor (MAF) applicable to single substance risk assessment to account for exposure to unintentional mixtures.

From science to policy: How European HBM indicators help to answer policy questions related to phthalates and DINCH exposure

“… Apel et al, 2020b ). The importance of mixture risk assessment (MRA) is also addressed in several communication papers 4 from the European Commission, and is also part of the European Chemicals Strategy for Sustainability 5 ( Bopp et al, 2018 ; Socianu et al, 2022 ). Within HBM4EU, chemical mixture risk assessment was also carried out for prioritized groups of chemicals, among them the phthalates.…”

Roadmap for action on Risk Assessment of Combined Exposure to Multiple Chemicals (RACEMiC)

“…The calculated HI-like risk metrics ranged from 2.8 (summing P50s, children) to 9.2 (summing P95s, adults). Six to seven substances contributed to over 95% of the total risk (Socianu, Bopp et al 2022). A number of uncertainties, such as limitation in the number of HBM-GV available for the assessment and a lack of possibilities to group the individual chemicals on the basis of mode of action as proposed in the EFSA guidance, were identified.…”

Developing human biomonitoring as a 21st century toolbox within the European exposure science strategy 2020–2030

“…In addition to giving information on the multiple sources of exposure from one chemical, HBM data give insight into co-exposure patterns of multiple chemicals. Consequently, HBM help in assessing combined exposures to chemical mixtures (Socianu et al 2022). Chemicals and chemical mixtures can be assumed to contribute to the global human burden of diseases (Prüss-Ustün et al 2011;Scholz et al 2022).…”