It has been reported worldwide that the enormous mountain of plastic (100 million tons) floating in the Pacific has been shrinking. Speculations about its whereabouts are evolving. With time plastic will break into smaller parts and become microplastic; the decomposition will take several years. In addition to all the macroplastic products we use, we also consume several products that contain microplastic.
Microplastic is used e.g. in toothpastes, fleece clothing, exfoliants, make-ups, detergents, and currently industry uses microplastic in sandblast, which was formerly made of sand. All these microplastic products are flushed to the sewer. Microplastic is only about 10 µm in size, so it will go straight through water treatment plants and into the ocean. Our oceans are thus full of both macro- and microplastic.
Macroplastics are hazardous to marine mammals, birds, and fish, but microplastic is hazardous to all kinds of animals. Plankton ingest microplastic from the water. From plankton it proceeds to plankton feeders such as mussels (Bivalvia), Gammarus, Mysidacea, and fry. The accumulation of microplastic will continue in the food chain, and eventually lead to us, humans. It is possible that there are huge amounts of microplastic in our bloodstream causing unknown effects.
For several years enormous effort has been put into studying the effects of macroplastic to marine mammals and birds, but perhaps the focus should be allocated to the microplastic cycle in the food chain.
To read more about microplastics in the food chains http://www.sciencedirect.com/science/article/pii/S0269749113005411