The Use of Conventional and Alternative Plastic Materials in Marine Environments: A Comparative Assessment of Material Degradation and Ecotoxicological Effects.

The environmental behaviour and safety of alternative plastic materials remain poorly understood, despite its increasing demand. This study assessed the degradation, and ecotoxicological effects of a conventional polyethylene (PE) bag, a compostable plastic bag, and tire granulate under simulated North Atlantic marine conditions. A 60-day mesocosm experiment was combined with biochemical oxygen demand (BOD) assays and toxicity tests using representative marine species. No visible structural degradation was observed for either PE or compostable bags during exposure, although biofilm formation developed on all materials. BOD results indicated negligible microbial degradation of the compostable plastic, suggesting limited biodegradability under marine conditions. While ecotoxicological responses differed strongly among materials. The tire granulate showed the highest and most persistent toxicity, reflecting its complex mixture of additives and transformation products. The compostable bag induced transient toxicity effects likely related to short-term additive release, while PE showed the lowest overall toxicity with minor temporal variation. Overall, results indicate that toxicity and environmental behaviour must be assed individually for each new material before promoting its implementation.