Source or Sink: Bioanalytical and Chemical Profiling of New and Field-Weathered Plastics

Abstract Plastics contain complex mixtures of chemicals that can leach into the aquatic environment. Conversely, the high sorption capacity of certain polymers renders plastics passive samplers for environmental pollutants from ambient waters. We evaluated whether effects from chemicals that are extractable or leachable from plastics from the North Pacific Ocean are dominated by plastic-associated or sorbed environmental compounds. First, bioanalytical profiling of chemical mixtures from solvent extracts of field-weathered marine plastics in cell-based bioassays was compared to that of chemicals from solvent extracts of newly purchased counterparts of the field plastics. Second, the new plastics were artificially UV-weathered and solvent-extracted, and the leachate waters were enriched with solid-phase extraction and dosed into a test battery of four in vitro bioassays where activation of the arylhydrocarbon receptor, oxidative stress response, and/or cytotoxicity were most responsive. Finally, chemical screening was performed using high-resolution mass spectrometry with subsequent mixture effect modeling to identify toxicity drivers. The results showed a multifaceted picture: Newly purchased high-durability outdoor products caused higher effects before weathering, whereas food packaging tended to show increased effects after field weathering. The analyzed chemicals could partially explain the observed effects (<0.1–98%). Our study underlines the relevance of field weathering for marine plastics and their potential to leach chemicals of concern into the environment.