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Biological responses of Chironomus sancticaroli to exposure to naturally aged PP microplastics under realistic concentrations
Summary
Researchers studied the toxicity of naturally aged polypropylene microplastics (26 micrometers, UV-aged) to larvae of Chironomus sancticaroli at ecologically realistic concentrations of 13.5, 67.5, and 135 items per gram of dry sediment over 144 hours, assessing fragment ingestion, mortality, and enzymatic biomarker changes. They found that organisms ingested microplastics from the first 48 hours, with internalized quantities increasing with exposure concentration, providing evidence of realistic-concentration biological responses in this freshwater dipteran species.
Abstract Microplastic (MP) is yet another form of chronic anthropogenic contribution to the environment. MP are plastic particles (< 5 mm) that have been widely found in the most diverse natural environments, but their real impacts on ecosystems are still under investigation. Here, we studied the toxicity of naturally aged secondary polypropylene (PP) MP after constant exposure to ultraviolet radiation (26 µm) to larvae of Chironomus sancticaroli, a dipteran species. The concentrations tested were 13.5; 67.5; and 135 items.g -1 of dry sediment. C. sancticaroli organisms were investigated for fragment ingestion, mortality and changes in enzymatic biomarkers after 144 hours of exposure. The organisms were able to ingest MP from the first 48 hours, and the amount of items internalized was dose-dependent and time-dependent. Overall, the results show that mortality was low, being significant at the lowest and highest concentrations (13.5 and 135 items.g -1 ). Regarding changes in enzyme markers, after 144 hours MDA and CAT activities were both significantly altered (increased and reduced, respectively), while SOD and GST levels were unchanged. In the present study, naturally aged polypropylene MP induced biochemical toxicity in C. sancticaroli larvae, with toxicity being higher according to exposure time and particle concentration.