Polymers are fundamental materials in modern society, with polypropylene (PP) being one of the most widely used thermoplastic polymers due to its flexibility, durability and adaptability to various applications. The addition of additives is essential for improving the mechanical properties of polymer materials. However, with the increasing global production and use of polymers, the amount of plastic waste is also increasing, which represents a major environmental challenge. Mechanical recycling is often promoted as a sustainable solution to reducing plastic waste. Although thermoplastics can theoretically withstand multiple recycling cycles without significant loss of properties, little research has been devoted to studying the impact of these processes on the release of additives, which can end up in the environment in the form as microplastics. The aim of this work was to analyze the effects of multiple mechanical recycling processes on release of additives from polypropylene microplastic. Two samples were prepared for this purpose. The first sample consisted of polypropylene with added antioxidants and plasticizer, while the second sample contained polypropylene with only antioxidant. After preparation, a simulation of five cycles of mechanical recycling were simulated in a laboratory extruder. After each recycling cycle, the samples were ground to microplastic size. Characterization of the samples was conducted after the 1st. 3rd and 5th cycles to determine changes in the properties of polypropylene caused by the migration of additives. Characterization methods included Fourier-Transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). These methods allowed monitoring changes in the chemical structure, thermal properties, and crystallinity of the polypropylene samples. The migration od additives from microplastics into water was also monitored, and the toxicity of water samples according to Vibrio fischeri bacterial culture, biodegradability ratio and total organic carbon content were determined.