Polyethylene Terephthalate Induced Oxidative Stress in Chlamydomonas reinhardtii: Implications for Intracellular Response Pathways and Ecosystem Health

Polyethylene terephthalate (PET) is a cheap and versatile plastic used primarily in textiles. We dispose of it as solid waste and in wastewater. It degrades into microplastics and decomposes into small molecules. This review explores recent studies on the impact on green algae of PET microplastic pollution in freshwater and soil. Using the example of the unicellular alga Chlamydomonas reinhardtii, a model organism for photosynthetic eukaryotes. The analysis explores mechanisms and outcomes of reactive‑oxygen‑species (ROS) generation, lipid peroxidation, and disrupted electron transport leading to impaired photosynthesis. Although most prior studies have targeted PET additives or dyes, evidence increasingly suggests that the PET polymer and its monomeric fragment, terephthalic acid, are not inert but ecotoxic. Proposed pathways link PET photodegradation and metal‑chelation chemistry to benzoquinone formation and chronic cellular oxidative stress. Yet existing data remain fragmented: few studies address decomposition kinetics, ion binding, or ecosystemic feedback in complex natural conditions. The article concludes that advancing quantitative, system‑level models of PET impact— and implementing stricter controls on PET dispersal through wastewater and biosolids—is essential to mitigate growing biospheric and economic risk.