Plastics and their effect on the environment is something that is currently being analyzed by science. Large pieces of plastic can become obstructions in the marine environment to both humans and marine organisms.
Other than the larger plastic materials in the environment, something that must be taken into account is the less visible impact of plastic on the environment. Micro-plastics are tiny plastic granules and fragments that come from broken down macro-plastics and other materials such as cosmetics and cleaners. Micro-plastics enter marine environments via, rivers, waste-systems, industrial drainage systems and other avenues. Due to the small size of these plastics as well as their prevalence in the environment, they are ingested by a wide variety of organisms along the food-chain. This has the potential to eventually affect humans as these toxic materials travel up the food-chain.
The effect that these micro-plastics have on the environment is still being analyzed. As stated before, micro-plastics can be consumed by very small organisms because of the small size of the material. This has potential to cause toxic responses in the organisms which can potentially effect humans. There is still much to be understood about micro-plastics and their impact on the environment. One thing is clear and that is that there is potential for negative impacts on the food-web as marine biota consume these plastic fragments.