Microplastic Contamination in the Marine Food Web

Plastics, with their versatile nature of lightweight and high resistance to microbial degradation, work their way into the global human society. Due to their unmanaged disposal, they ultimately reach the ocean. The United Nations Environment Program (2018) has estimated that approximately 13 million tons of plastic enter into the oceans every year. Upon degradation, these plastics are converted to microplastics (MPs) and are distributed to the entire water column, and become part of benthic sediments. They can be found from the Arctic to the Antarctic oceans, and these MPs have a toxicity effect on the marine biota from producer to top consumer when they travel to the successive trophic level of the marine food web. The marine fauna like polychaete, mollusks, fish, birds, mammals, turtles, etc., are often confused with these MPs and their food and consume them, which causes toxicity to them. MPs reach humans through seafood consumption; the impact of MP absorption on the human gastrointestinal tract is relatively lesser when compared with nanoplastics. However, their absorbance and accumulation in the liver and brain are higher among other human organs. Research studies suggest that heavy metal toxicity increases with the MP accumulation in the organism's body. Therefore, the associated toxicity risk is higher with MPs, as they act as a vector for indigenous and non-indigenous species.