Avaliação comparativa do ciclo de vida ambiental de plásticos PET e PLA: foco nos impactos relacionados à geração de macroplásticos e microplásticos

Abstract

Plastic pollution is a current environmental challenge that causes significant negative impacts on terrestrial and aquatic ecosystems. The fragmentation of plastic waste over time results in the formation of macroplastics and microplastics, which persist in the environment and can affect wildlife, biogeochemical cycles, and potentially human health. In this context, the replacement of fossil-based plastics with biodegradable alternatives has been identified as a promising strategy. However, the environmental benefits throughout the life cycle of these materials still require in-depth evaluation. This study aims to carry out a comparative environmental life cycle assessment (LCA) of poly (ethylene terephthalate) (PET) and poly (lactic acid) (PLA) polymers, focusing on macroplastic and microplastic generation. Four scenarios were considered, involving production routes, importation, and different end-of-life options within the Brazilian context, using the software Simapro and the Ecoinvent 3.8 database, using as the functional unit a cup with lid, the the volume of 473 mL. The results indicated that PET has a higher potential for macroplastic generation, especially in scenarios with inadequate waste disposal, due to its higher consumption volume and greater susceptibility to leakage at end-of-life. PLA, in turn, exhibited lower macroplastic generation, particularly in scenarios that considered industrial composting as the final disposal route. Regarding microparticles, both life cycles showed significant contributions associated with road transport, due to tire wear and the release of elastomeric fragment particles. However, for PLA, the values were higher than for PET, reflecting its greater reliance on road transport within the analyzed life cycle. The partial replacement of maritime and road transport with more sustainable alternatives, such as rail transport combined with the use of biofuels or electricity from renewable sources, showed potential to reduce microplastic/microparticle leakage and contributed to decreasing impacts related to terrestrial acidification (17.8% for PET and 12.2% for PLA) and global warming (2.8% for PET and 3% for PLA). Higher waste collection coverage, in turn, showed potential to reduce macroplastic leakage. The study reinforces that, in addition to the choice of polymer type, the implementation of integrated strategies, such as domestic production, improvements in transport logistics, and the promotion of industrial composting, is essential to reduce the contribution of plastic materials to the environmental burden of macro- and microplastics. Overall, PET shows higher climate, pollution, and fossil fuel consumption impacts, while PLA has lower emissions but higher impacts on land use, mineral resource depletion, and microplastic leakage. Thus, although PLA performs better in terms of emissions and general pollution, it is not free from relevant impacts, requiring a complete life cycle assessment for a more sustainable choice.