Plastic does not have to be large to harm the environment. 

Microplastics are tiny but just as harmful as larger pieces of plastic.

Microplastics can be consumed by plankton and smaller fish and thus enter the food chain and ultimately find their way to the top of the food chain.

https://www.istockphoto.com/vector/illustrative-diagram-of-how-microplastics-pollute-the-environment-gm1305691614-396501853

Microplastics have entered the food chain and have been detected in every level of marine organism, from plankton to whales.

https://theoceancleanup.com/great-pacific-garbage-patch/

When the fish eat plastic, so do we when we consume seafood. Plastic affects every living creature in this food chain, including humans. Belgian scientists have estimated seafood lovers would consume 11,000 plastic particles in one year from consuming mussels. Microplastics have been found in breast milk of otherwise healthy mothers. Finally, scientists from the Netherlands and UK have discovered plastic particles in living humans, in the lungs of surgical patients and in the blood of donors.