The Eco‐Exposome Concept: Supporting an Integrated Assessment of Mixtures of Environmental Chemicals

Abstract

Organisms are exposed to ever-changing complex mixtures of chemicals over the course of their lifetime. The need to more comprehensively describe this exposure and relate it to adverse health effects has led to formulation of the exposome concept in human toxicology. Whether this concept has utility in the context of environmental hazard and risk assessment has not been discussed in detail. In this Critical Perspective, we propose-by analogy to the human exposometo define the eco-exposome as the totality of the internal exposure (anthropogenic and natural chemicals, their biotransformation products or adducts, and endogenous signaling molecules that may be sensitive to an anthropogenic chemical exposure) over the lifetime of an ecologically relevant organism. We describe how targeted and nontargeted chemical analyses and bioassays can be employed to characterize this exposure and discuss how the adverse outcome pathway concept could be used to link this exposure to adverse effects. Available methods, their limitations, and/or requirement for improvements for practical application of the eco-exposome concept are discussed. Even though analysis of the eco-exposome can be resource-intensive and challenging, new approaches and technologies make this assessment increasingly feasible. Furthermore, an improved understanding of mechanistic relationships between external chemical exposure(s), internal chemical exposure(s), and biological effects could result in the development of proxies, that is, relatively simple chemical and biological measurements that could be used to complement internal exposure assessment or infer the internal exposure when it is difficult to measure.

Pervasive exposure of wild small mammals to legacy and currently used pesticide mixtures in arable landscapes

“…The use of multi-residue analyses reveals the accumulation of complex mixtures of compounds in wildlife, which reflects a co-exposure that might be caused by simultaneous, successive or cumulative multiple exposure 78 . The ecotoxicological significance of such a co-exposure might be due to either chronic long-term exposure to low doses, or acute short-term exposure to peaks but possibly recurrent, or both.…”

“…Our results also raise questions about the ecotoxicological consequences of such an exposure to pesticide mixtures and provide useful data about the composition of the mixtures to be studied. This warrants further research about mixture toxicity and advocates for the development of toxicological reference values and critical body residues, especially for CUPs, as done for many other contaminants within the last decades 78 , 87 . This should be done fostering animal welfare and reduction of animal use, for instance by optimizing laboratory testing with assessment of both toxicity endpoints, including sublethal ones, and bioaccumulation at once and with refined methods to assess toxicological responses 88 , and focusing on non-invasive sampling through analysis of body fluids, faeces and hair or feathers 42 ).…”

“…This should be done fostering animal welfare and reduction of animal use, for instance by optimizing laboratory testing with assessment of both toxicity endpoints, including sublethal ones, and bioaccumulation at once and with refined methods to assess toxicological responses 88 , and focusing on non-invasive sampling through analysis of body fluids, faeces and hair or feathers 42 ). The continuous improvements in analytical chemistry allowing multi-residue measurements in complex matrices and conceptual developments about exposome 78 pave the way for further investigation about exposure to mixtures and “biowidening”. These issues deserve further attention and warrant further research about wildlife exposure to and contamination by CUP, which are currently sparsely studied and surveyed apart from the modelling approaches applied during marketing authorization and toxicovigilance.…”

Merging the exposome into an integrated framework for “omics” sciences

“…The vision was subsequently explained and positioned within systems toxicology ( Escher et al., 2017 ) at the interface of aggregate exposure pathway (AEP) and adverse outcome pathway (AOP) frameworks, yet the definition remained abstruse. A further re-definition narrowed the eco-exposome to represent “the totality of internal exposure over a lifetime to individuals of a given species” ( Scholz et al., 2022 ). The definition was presented as exclusive for chemicals and has limited applicability to ecological communities and holobionts, both in phrasing and the disregard of psychosocial (and physical) factors.…”

Interaction of Layered Silicates with Biomembranes: Ion Exchangers and Non‐Exchangers

“…Thus, mechanistic knowledge of the biophysicochemical interactions of LS would also be crucial in complementing the eco-exposome to mineral dusts, to determine the primary risk drivers in complex mixtures. [13] LS particles and their derived nanocomposites are generally considered biocompatible, promoting cell adhesion and proliferation. [9c,10a] However, concerns regarding the possible cell damage caused by LS Layered silicates (LS, clays) are a composite group of minerals whose industrial interest and technological applications are progressively expanding, spanning from catalysis to biomedicine.…”