The paper reviews the degradation pathways and products of six commonly used plastic polymers in Europe: polyethylene (PE), polypropylene (PP), polystyrene (PS), poly(vinyl chloride) (PVC), poly(ethylene terephthalate) (PET), and polyurethane (PU). These plastics are exposed to sunlight, oxidants, and physical stress in marine environments, leading to weathering and degradation. The degradation processes depend on the polymer type, with UV radiation and oxygen initiating chain scission for carbon-carbon backbones, and photo-oxidation, hydrolysis, and biodegradation for polymers with heteroatoms. Smaller polymer fragments formed by chain scission are more susceptible to biodegradation. The degradation products include low molecular weight polymer fragments, monomers, oligomers, and carboxylic acids. The paper also discusses the environmental impact of plastic pollution, emphasizing the need for more studies under marine conditions to understand degradation rates and products.The paper reviews the degradation pathways and products of six commonly used plastic polymers in Europe: polyethylene (PE), polypropylene (PP), polystyrene (PS), poly(vinyl chloride) (PVC), poly(ethylene terephthalate) (PET), and polyurethane (PU). These plastics are exposed to sunlight, oxidants, and physical stress in marine environments, leading to weathering and degradation. The degradation processes depend on the polymer type, with UV radiation and oxygen initiating chain scission for carbon-carbon backbones, and photo-oxidation, hydrolysis, and biodegradation for polymers with heteroatoms. Smaller polymer fragments formed by chain scission are more susceptible to biodegradation. The degradation products include low molecular weight polymer fragments, monomers, oligomers, and carboxylic acids. The paper also discusses the environmental impact of plastic pollution, emphasizing the need for more studies under marine conditions to understand degradation rates and products.