Sure there is, but there is a huge difference between dumping plastic waste into rivers like it happens in India, Africa etc and then being able to measure trace amounts of microplastics in the environment. Of course plastics left in nature will eventually find its way into the water streams.

I mean its still a problem. "We're not as bad as the third world" isn't really an argument

You might want to read up on that thing about plastic coming from a few chines and indian rivers, because it's wrong.