Study of fibrous microplastic and natural microfiber levels in branded milk samples from Italy

As far as we know, there is no evidence regarding the microfiber (MF) occurrence and abundance in branded milk samples from Italy. Therefore, a total of 20 milk samples from 5 brands were collected and analyzed using a digestion step with hydrogen peroxide, followed by filtration. Natural and synthetic MFs were classified according to the evaluation of surface morphology (i.e., shape and texture), followed by chemical identification using Fourier Transform Infrared (FTIR) Microspectroscopy. Results revealed the occurrence of MFs in 67.5% of the analyzed samples and showed variability ranging between 1 and 27 particles/100 mL with an overall average of 3.85 MFs/100 mL. The FTIR analyses confirmed the presence of polyethylene, polyester, acrylic, and cellulosic MFs. According to the literature, the contamination of milk may occur at various stages along the production chain. The blood-milk barrier would prevent MFs from being transferred across the mammary gland into the milk. The highest MF levels found in ultra-high temperature skimmed milk of some brands may indicate that the more complex the processing of milk, the more MFs it contains. However, due to the different MF types and polymers, an unambiguous conclusion on MF sources cannot be made. MFs could be shed from the filters used in the milk processing factories and the protective clothing for workers. Therefore, the MF contamination should be properly investigated along the entire supply chain, identifying the sources of contamination and implementing control strategies and mitigation measures.