First characterization of the ecotoxicity of paraffin particles: assessment of biochemical effects in the marine polychaeteHediste diversicolor

Plastics are a widespread environmental problem, particularly in the form of small particles or fragments (microplastics). With the purpose of gradually replacing the use of plastics in cosmetic products (primary microplastics), the use of paraffin in microspheres has recently been applied. Paraffin waxes are composed by organic molecules usually derived from petroleum, thus assumed to be chemically and biologically inert, having a lower (eco)toxicity and residence time compared with plastic particles. However, the low ecotoxicity of paraffin waxes may be somewhat questionable, because some paraffin constituents can be absorbed and catabolized, thus exerting biological effects. The main objective of this study was to understand the potential toxic effects of paraffin microparticles on key physiological processes of the polychaeteHediste diversicolor. To attain this objective, this work assessed the acute and chronic effects of three densities (5, 20, and 80 mg L-1) of four size ranges of paraffin particles (from 100 to 1200 mu m) on this epibenthic organism. Although paraffin wax can be generically considered innocuous, the present study was able to demonstrate a significant inhibition in the activity of acetylcholinesterase in acutely exposed organisms and an increase in the activity of glutathione peroxidase, catalase, and glutathione S-transferase under some specific scenarios.Bruno Nunes is hired by "ECO-R-pharmplast Ecotoxicity of realistic combinations of pharmaceutical drugs and microplastics in marine ecosystems", Fundacao para a Ciencia e aTecnologia, FCT (reference POCI-01-0145-FEDER-029203). This research was financially supported by CESAM(UIDB/50017/2020+UIDP/50017/2020), by FCT/MCTES through national funds (PIDDAC), and by the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020