Multispecies toxicity evaluation of extractable chemicals from commercial biodegradable plastic products

Biodegradable plastics (BDPs) have been developed as potential solutions to plastic pollution under the premise that they could reduce environmental accumulation when compared with conventional non-degradable plastics. However, the ecotoxicological risks associated with extractable chemicals, including additives and non-intentionally added substances (NIAS), used to optimize material performance remain poorly understood. The present study conducted an integrated evaluation of the chemical composition and multispecies toxicity of extractable chemical mixtures from 12 commercial polylactic acid- and polybutylene adipate terephthalate-based products using ultrasound-assisted extraction. Chemical analyses using gas chromatography-mass spectrometry and inductively coupled plasma mass spectrometry identified regulated additives such as dibutyl phthalate (DBP) and triphenyl phosphate, in addition to NIAS. Multispecies bioassays demonstrated that plastic extracts induced significant toxicity across diverse taxonomic groups, including root growth inhibition in Raphanus sativus, mortality in marine copepods (Tigriopus japonicus), membrane damage in soil bacteria (Bacillus subtilis), and decreased cell viability in human-derived cell lines (HaCaT and HepG2). By integrating the multispecies toxicological data, Principal Component Analysis identified key chemical constituents correlated with the observed toxic responses. Subsequent single-substance toxicity assays revealed that a specific additive induced more potent reactive oxygen species generation and lactate dehydrogenase leakage in human cells than DBP, a regulated phthalate. Despite the intended environmental benefits of BDPs, the present study highlights potential hazards posed by extractable compounds present at commercial levels. The findings of the present study underscore that safety evaluations of BDPs should consider additive-based mixture toxicity in addition to polymer degradability.