Confounding factors in nano and microplastic ecological risk assessment

Over the last 5 years, micro and nanoplastic ecotoxicology has emerged as a new field of research with new paradigms and the development of new tools to evaluate the fate and impact of these contaminants in the environment. If a lot of progress has been made so far, there is still many discrepancies in the scientific literature on that topic with no general consensus on the toxicity of the different forms of micro and nanoplastics and very little information on the underlying mechanisms. Based on the research we have been carrying out in the lab for these last 5 years, we have been able to identify some confounding factors that should be considered to reach robust conclusions in ecological risk assessment. For instance, we highlighted the impact of plastic physico-chemical characteristics as well as exposure medium on plastic uptake and toxicity in a crop plant. Also in terrestrial ecosystems, we investigated to which extent soil type can control plastic biodegradation. Additionally, in freshwater ecosystems, we evidenced the importance of studying contaminant effects in microcosms including both abiotic and biotic compartments to take into account their interactions as they may play a significant role in mitigating contaminant effects. Finally, considering different ecosystems (marine, freshwater and soil), we demonstrated that the same plastic contamination could lead to diverse effect on one important ecosystem function: bioturbation. These different studies shed light on the importance of identifying confounding factors in ecotoxicity studies and their contribution to include them in ecological risk assessment. Also see: https://micro2024.sciencesconf.org/559129/document