Aim of the project is evaluate the impact of the microplastics on live cells and organisms exposed to these materials by inhalation or in aquatic environment. In this work we focus the attention to the toxic potential of no-commercial MPs, keeping into mind… Read more that eventual adverse effects of MPs could be caused both by the physical properties of particles and also other factors, e.g. delivered chemical pollutants. In particular, microparticles obtained from waste plastics will be used. Waste plastic granules were obtained from plastic recycling plants and the micron-sized fraction recovered in lab after serial mechanical sievings. The smallest fractions of the plastic granules, considered as representative of the environmental MPs, are characterized by polymers mixtures and other residues (additives, metals, etc...) and will be been used to perform toxicity tests using in vitro and in vivo systems representative of an inhalation and aquatic exposure scenarios respectively. The toxic responses, as well as the modality of the MP interactions with the biological structures will be been investigated in Polaris Laboratories (Unimib), according to standard toxicological tests (cell viability, pro-inflammatory response and cell cycle analyses). The target will be epithelial cells, fibroblasts and cells involved in the inflammatory response, exposed to increasing concentrations of MP suspensions. Before proceeding with biological tests the microplastic granulates must be adequately characterized in size and morphology. Therefore, plastic heterogeneous fractions will be mechanically grinded in User laboratory to obtain MP fractions of < 100 μm and < 50 μm. MPs will be morphologically charaterized by polarized light, fluorescence and Scanning Electron Microscopes (SEM) localized in Lead users facility( UNIMIB). Preliminary observations of these MPs samples are shown in Figure 1. Moreover, polymeric composition of the MP fractions will be analyzed by ATR-FTIR spectroscopy (Nicolet In5 FTIR) also available in DISAT department of UNIMIB. Preliminary data obtained by this analytical approach revealed that MPs are mostly constituted by polyethylene and polypropylene.