Commercially-derived Microplastics Affect Early Life Stages in Paracentrotus Lividus Sea Urchin

Nowadays, plastic pollution in the marine environment poses a serious risk to aquatic organisms. The main concern is the possibility that plastics can spread microplastics (MPs), but also the release of chemical additives added during the manufacturing processes of plastic products widely used in our daily life. The use of substances added to plastic objects together with the incorrect management of products at their end-of-life, also makes biodegradable polymers (BPs), proposed as an alternative to conventional plastics to reduce environmental impact, potentially toxic.1 In this work the early life stages of the sea urchin Paracentrotus lividus were used to evaluate the possible toxic effect of MPs obtained from commercial tableware made of three commonly used polymers: polypropylene (PP; 38-212 μm), polystyrene (PS; 318 ± 187 μm) and polylactic acid (PLA; 38-212 μm). Eggs of P. lividus were exposed to PLA, PP and PS MPs for ten minutes at increasing concentrations (1, 5, 10, 12.5, 25, 50 and 100 mg/L), then fertilized and the embryonic development was followed until 48 hours post fertilization to detect the fertilization and the first mitotic division, as well as the presence of malformed plutei. Our results showed that all three polymers blocked the first mitotic division already at the lowest concentrations tested, also inducing a delay of embryonic development, with a dose-dependent increase of embryos still at the blastula and gastrula stages, as well as malformations of embryos that reached the pluteus stage. However, PLA was found the least toxic polymer compared to PP and PS. These results translated at the molecular level in the up-regulation of the expression of most of the eighty-seven genes analyzed (involved in development and differentiation, skeletogenesis, stress response and detoxification processes) in embryos exposed to PLA and PP. Differently PS induced the down- regulation of these genes, these results provide deeper insight into the mechanisms of commercially derived MPs, highlighting both immediate and prolonged risks for marine organisms. This work was realised in the framework of the Project - Biomonitoraggio di micro e nanoplastiche biodegradabili: dall'ambiente all'uomo in una prospettiva one health (BioPlast4Safe) - with the technical and economic support of the Italian Ministry of Health – PNC.