Combined effects of nanoparticles and other environmental contaminants on human health - an issue often overlooked

Abstract

Air pollution is considered as a major public health issue worldwide. It consists of a complex mixture of pollutants including nanoparticles to which we are increasingly exposed to due to the dramatic development of the nanotechnologies and their incidental or intentional release in the environment. Consequently, some concerns have raised about the combined toxicity of air particulates and other air pollutants on human health. However, the interactions between the contaminants and their resulting combined toxicity are often overlooked. Indeed, the biological effects triggered by nanoparticles are usually assessed focusing on individual nanoparticles, while their interaction with co-contaminants can deeply impact, either positively or negatively, their biodistribution, fate in the organism and toxicological profile (additive, synergistic or antagonistic responses). This paper presents a bibliographic review on the combined toxicity of nanoparticles and co-pollutants and discusses the underlying mechanisms. It also highlights the scarcity of data in the current literature, arguing for an urgent need to take into account the mixture effects to be more representative of real-life conditions for a better and accurate human health risk assessment and management.

Establishment of Repeated In Vitro Exposure System for Evaluating Pulmonary Toxicity of Representative Criteria Air Pollutants Using Advanced Bronchial Mucosa Models

“…is usually assessed by focusing on a particular air pollutant, while their interaction with co-contaminants can have a deep impact, either positively or negatively. However, the interactions between the contaminants and their resulting combined cellular toxicity or molecular response on in vitro or in vivo studies are often overlooked [57].…”

Nanomaterial Ecotoxicology in the Terrestrial and Aquatic Environment: A Systematic Review

“…NMs can be transformed once in the environment, due to the interaction with natural parameters in the terrestrial and aquatic ecosystems (e.g., salinity, pH, temperature, organic matter) and to the presence of other contaminants (e.g., metals, chemicals, emerging compounds). The NMs can be a sink for organic and inorganic co-contaminants that may modify NMs’ physicochemical properties and behavior over time [ 60 ]; the interaction between NMs and other co-contaminants can impact NMs fate, distribution, and ecotoxicity, inducing additive, synergistic, or antagonistic responses [ 69 , 70 ]. On the other hand, NMs interact with a biological counterpart that forms a biological surface, coating the NMs.…”

Experimental and Computational Nanotoxicology—Complementary Approaches for Nanomaterial Hazard Assessment

“…It is thus difficult to reproduce such complexity in experiments; therefore, samples used in nanotoxicology assessment are not always fully representative of real-life exposure and may not lead to accurate human health risk assessment and management as they overlook the interactions between the contaminants and their resulting combined toxicity [123]. Indeed, the biological effects triggered by nanoparticles are usually assessed focusing on individual nanoparticles [124,125], while their interaction with cocontaminants can deeply impact, either positively or negatively, their biodistribution, fate in the organism, and toxicological profile (additive, synergistic, or antagonistic responses) [123,126]. Even if the toxicities of individual compounds are well characterized, unexpected adverse effects can be induced by the mixing of such compounds [127,128].…”

“…Different mechanisms can be responsible for combined toxicity [123]. A carrier effect can be observed where the co-pollutant adsorbs at the surface of the nanomaterial that serves as a cargo and eases the entry and accumulation of the co-pollutant inside the cell.…”

“…Despite the complexity of the issue (there are countless potential mixtures in our environment) and the technical difficulty to recapitulate real-life conditions, it seems crucial to take into account mixture effects [123]. Furthermore, if nanomaterial exposure is usually well considered during the production and manufacturing stages, it is less systematically evaluated during the use and end-of-life stages [81,112].…”