>there's plenty of research that needs to be done still in this field

Doesn't appear to be any kind of quantification of damage, however. The size of the problem appears to be unknown, but we can conclude it's relatively small, otherwise it would be easier to detect and quantify.

>On that note, show me a fish, and I'll show you plastic.

Plastic that didn't make it to a landfill or incinerator, sure. But when properly disposed of, that's not an issue.