Environmental and littering impacts of disposable cups made of polypropylene and polylactic acid in Germany

As a result of improper management, plastics such as drinking cups are accumulating in environmental compartments worldwide, impacting biodiversity and ecosystem services. The goal of this study is to analyze and compare potential environmental impacts of disposable cups made of Polypropylene and Polylactic acid with the help of a cradle-to-grave life cycle assessment, including impacts related to the littering of these cups. Plastic pollution impacts are calculated based on the products' persistence in the environment, comparing the results of our own experiment to literature data. As an indication of the possible adverse health effects of Polypropylene and Polylactic acid, a toxicity test of the chemical mixtures migrating from the cups is conducted. Overall, the cups made of Polypropylene show lower environmental impacts compared to those made of Polylactic acid when the experimentally determined degradation rates are used. Nevertheless, regarding toxicity of the chemical migrates, the cup made of Polylactic acid performs better than the one made of Polypropylene. Considering all impact categories, there is no overall improvement in environmental impacts of producing the cup from Polylactic acid instead of Polypropylene. Our results indicate the importance of using degradation data measured specifically for the assessed product. Methodologically, we demonstrate a possible integration of life cycle assessment and safe-and-sustainable-by-design scoring. Further development of the plastic pollution impact category is needed to integrate effects on the terrestrial environment.