Tracking complex mixtures of chemicals in our changing environment

Abstract

Chemicals have improved our quality of life, but the resulting environmental pollution has the potential to cause detrimental effects on humans and the environment. People and biota are chronically exposed to thousands of chemicals from various environmental sources through multiple pathways. Environmental chemists and toxicologists have moved beyond detecting and quantifying single chemicals to characterizing complex mixtures of chemicals in indoor and outdoor environments and biological matrices. We highlight analytical and bioanalytical approaches to isolating, characterizing, and tracking groups of chemicals of concern in complex matrices. Techniques that combine chemical analysis and bioassays have the potential to facilitate the identification of mixtures of chemicals that pose a combined risk.

Fig. 1.. From sampling to (bio)analysis of complex environmental mixtures in the environment and in humans, from past to present and into the future.

NTA, non-target analysis.

Fig. 2.. Spotlight on the chemical universe.

(A) Chemical analysis. (B) Bioanalytical tools. The overlap that exists between the chemicals “seen” by chemical analysis and bioanalysis is not depicted. The chemicals depicted are illustrative examples; selection is not comprehensive.

Fig. 3.. Illustrative example of occurrence of chemicals in suspect screening of various matrices: biota (fish, mussels), seawater, and sediments.

Presence or absence is indicated; green indicates presence with at least six MS/MS fragments. [Created/modified from https://norman-data.eu/NORMAN-REACH/; details in (25)]

Fig. 4.. Mixture toxicity models for linking detected concentrations with predicted and experimental mixture effects.

(A) Example for calculation of BEQ_chem from concentrations C_i and relative effect potencies REP_i. (B and C) Comparison between the predicted mixture effects of the detected chemicals (BEQ_chem) and those directly measured in bioassays (BEQ_bio) allows derivation of the effect contribution of the unknown chemicals (BEQ_unknown). For specific modes of action (MOA), BEQ_chem is often close to BEQ_bio (B); for nonspecific effects, BEQ_unknown is large (C).