Nanoplastics and biota behaviour: Known effects, environmental relevance, and research needs

Behaviour is increasingly recognized as a sensitive screening tool to detect the effects of environmental disturbances on biota, resulting from molecular, biochemical, and physiological processes. In this sense, several (eco)toxicological studies have been assessing and reporting the behavioural effects of xenobiotics, even at very low doses. Different behavioural endpoints may help to estimate more accurately the impact of nanoplastics (NPLs) in fitness-related behaviours and, therefore, should be included in environmentally relevant exposure scenarios. This paper presents a critical review of current scientific knowledge regarding tested behavioural endpoints on freshwater organisms exposed to NPLs, findings’ environmental relevance and research needs. Overall, the limited number of studies addressed only 3 types of polymers, with spherical polystyrene (PS) being the most studied, but all identified behaviour as a sensitive endpoint to NPLs exposure, with potential effects on populations. However, applied methodologies differ making comparison of effects between different sizes or polymers difficult.