Plastic pollution is now considered a global threat. Plastics introduced into the environment remain there for dozens or even hundreds of years. They gradually break down into smaller and smaller fractions, the so-called microplastics (MPs) that enter various environmental ecosystems such as soil, water and air. It is estimated that between 19 and 23 million tonnes of plastic end up in the ocean each year, representing less than 3% of the total amount of mismanaged plastic waste. In turn, the amount of this waste that is released into the environment is ten times greater (about 30% of the total). MPs entering rivers, lakes or dam reservoirs from land may pose a threat to the living organisms inhabiting them and entire ecosystems. The breakdown of microplastics in aquatic ecosystems leads to the release of toxic chemical substances into the aquatic environment. These substances, which are components of plastics, include plasticizers, stabilizers, pigments and flame retardants. This study presents research on the potential emission of plasticizers into the aquatic environment from water and sewage installations, such as sewer pipes and accompanying elements (gaskets). The conducted research confirmed that, depending on environmental conditions, phthalate esters are leached from microplastics originating from water and sewage systems. The reaction environment temperature and incubation time significantly influenced the degree of plasticizer leaching from the polymer matrix. An additional negative aspect of microplastic degradation in the aquatic environment was the emission of greenhouse gases, such as carbon dioxide and methane. To determine the parameters that had the greatest impact on the emission levels of the analyzed contaminants from microplastics, an environmental model sensitivity analysis was conducted based on Hellwig's information capacity index analysis.