Alternative plastic materials pose higher chemical hazard and aquatic ecotoxicity than conventional plastics

A comparative ecotoxicological profile was conducted on plastic materials with the same use made of conventional polymers versus alternative, potentially biodegradable polymers, frequently marketed as "bio" with claims of lower ecological impact. The sensitive in vivo sea-urchin embryo test (SET) was used for the ecotoxicological characterization, and non-target chemical analyses using GC-MS for the chemical profiling. Toxicological properties of identified chemicals were compiled from ECHA, and NIH databases using an in-house developed Python tool, and qualitative and semiquantitative Chemical Hazard Indices (CHI) were calculated for each material. The alternative materials exhibited on average 2- to 3-fold higher CHI values compared to conventional materials. All PE items, including recycled and oxodegradable samples, lacked any in vivo ecotoxicity, whereas all compostable items showed a certain degree of in vivo toxicity except for the PLA cups. The top six materials containing the highest concentrations of category 1 reproductive toxicity phthalates were all alternative plastics: the recycled bag, compostable knives, PHB resin, and both home-compostable trash sacs. Therefore, while degradable plastics may contribute to reduce the environmental persistence of plastic items, they do not necessarily reduce their ecotoxicological impact, and may increase their chemical hazard.