After use, discarded plastics can stay in outdoor environment if their conditions of storage are not enough safe. They will be then exposed to climatic factors (UV solar radiations, heat, rain, pollution,…) and will end up in freshwater or in marine water. They are submitted to photo ageing and a consequence a possible size reduction through a fragmentation process which results in micro plastic formation. In parallel the macromolecular polymer undergo a photo chemical oxidation mechanism leading to the formation of degradation by-products. We have studied and examined how chemicals molecules can be transferred from the solid plastic pieces to the aqueous medium along this degradation process.