The textile industry is globally significant for human comfort but relies on complex processes that involve large quantities of chemicals, many of which have toxic and ecotoxic effects throughout their life cycle. Among the most concerning substances are synthetic dyes and pigments containing heavy metals, as well as per- and polyfluorinated alkyl substances (PFAS), which are widely used as repellents. Due to their persistence and bioaccumulative nature, these chemicals pose significant environmental risks, yet safety data on their presence in textiles remains limited. To address this research gap, we conducted an up-flow percolation test to identify and characterize heavy metals and PFAS in textile waste, following the European Technical Standard CEN/TS 14405. Our preliminary results revealed the presence of Al, As, Co, Cr, Cu, Fe, Mn, Pb, Zn, and Sb in leachates, with Al, Cr, Fe, Mn, and Zn being predominant. Trace levels of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and 8:2 fluorotelomer sulfonate were also detected above the detection limit. These findings highlight the need for further research on chemical migration from textiles. In the next phase, we will perform similar tests on new textiles to compare their leaching behavior with textile waste. This comparative approach will provide deeper insights into the persistence of hazardous substances and their potential release over the textile lifecycle. Our research aims to contribute to the development of safer textile production and waste management strategies.