UV-degradation is a key driver of the fate and impacts of marine plastics. How can laboratory experiments be designed to effectively inform risk assessment?

• Published in: Marine pollution bulletin Vol. 219; p. 118271
• Main Authors: Hernandez, Laura M., Howarth-Forster, Lucy, Sørensen, Lisbet, Booth, Andy M., Vidal, Alice, Tufenkji, Nathalie, Sempéré, Richard, Schmidt, Natascha
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2025; Elsevier
• Subjects: Environmental Monitoring; Environmental Sciences; Marine litter; Microplastic; Photolysis; Plastic fragmentation; Plastic pollution; Plastics - analysis; Plastics - chemistry; Risk Assessment; Sciences of the Universe; Seawater; Seawater - chemistry; Sunlight; Ultraviolet Rays; Water Pollutants, Chemical - analysis; Plastic fragmentation; Sunlight; Microplastic; Marine litter; Seawater; Plastic pollution
• ISSN: 0025-326X; 1879-3363; 1879-3363
• DOI: 10.1016/j.marpolbul.2025.118271

Marine plastic litter is subject to different abiotic and biotic forces that lead to its degradation, the main driver being UV-induced photodegradation. Since UV-exposure leads to both physical and chemical degradation of plastic, leading to a release of micro- and nanoplastics as well as leaching of chemicals and degradation products – it is expected to have radical impacts on plastics fate and effects in the marine environment. The number of laboratory studies investigating the mechanisms of plastic UV-degradation in seawater has increased significantly in the past 10 years, but are the exposures designed in a manner that allow observations to be extrapolated to environmental fate? Most studies to date focus on quantifying plastic fragmentation and surface changes, but is this relevant for impact assessments? Here, we provide a review of the current scientific literature on UV-degradation of plastic under marine conditions. Plastic fragmentation processes and surface changes as well as implications of UV-degradation of plastics on additive leaching and the toxicity of UV-weathered versus non-weathered plastics are highlighted. Furthermore, experimental set-ups are critically inspected and recommendations for future studies are issued. [Display omitted] •700 % increase in number of studies from 2016 to 2022•Most studies focus on investigating the physical degradation of the plastic.•Future works should focus on realistic scenarios and interdisciplinary approaches.•Recommend analyzing material properties, surface changes, fragmentation & leaching•Harmonized methodology increases data comparability, facilitating risk assessment.