You may try searching for the components present in certain microplastics that are harmful, e.g. (BPA) bisphenol A [0].
Microplastics that have been generated from plastics containing BPA that are then lodged into the food chain from a very low level will have serious consequences, as BPA is an endocrine disrupter, and shown to negatively affect many physiologial systems including human sperm [1].