Physicochemical transformation and toxic potential of polyethylene terephthalate (PET) fragments exposed to natural daylight

• Insights into the negative effects of chemical substances leached by PET fragments. • The chemical composition of leachates from photoaged PET fragments was more complex. • GC–MS analysis identified various organic compounds, including plasticizers. • Inorganic metals, such as antimony and titanium were detected by ICP-MS/MS analysis. • Photoaged samples were found to be more toxic to Tisochrysis lutea and Aliivibrio fischeri. Since the widespread use of plastics in various aspects of daily life has led to significant environmental concern due to the generation of microplastics (MPs) and the leaching of chemical additives, the present study investigates the physicochemical transformation and characterization as well as the toxic potential of polyethylene terephthalate (PET) fragments exposed to natural daylight for 15 and 30 days (daylight-aged or photoaged PET). Raman analysis confirmed PET composition, while GC–MS and ICP-MS/MS analysis identified organic compounds, including plasticizers, and inorganic metals, such as antimony and titanium. According to the results, photoaged PET leachates had a more complicated composition than samples not exposed to daylight (PET virgin ), as higher number of organic and inorganic compounds were detected, indicating enhanced degradation under light exposure. Ecotoxicological bioassays were also performed using Tisochrysis lutea and Aliivibrio fischeri as biological models and light-aged PET leachates were found to have higher toxic effects, leading to growth inhibition in microalgae and a reduction in the bioluminescence of bacteria. Exposure to light-aged PET leachates caused initial algal growth inhibition in T. lutea , as well as bacterial bioluminescence inhibition in A. fischeri which later diminished. Moreover, chlorophyll and carotenoid content were measured to assess potential effects on microalgae, further elucidating the ecological consequences of PET photodegradation. These findings underscore the complex interactions between plastic degradation, additive leaching, and biological responses, emphasizing the need for comprehensive assessments to understand the ecological ramifications of (micro)plastic pollution. Moreover, the risks of plastic pollution are highlighted, rendering the development of eco-friendly plastic alternatives and enactment of stricter waste management regulations an urgent necessity.