Exactly, so while the authors are ringing alarms about the particles from a health POV, they might be a irrelevant to that threat, but a major threat to certain ecosystems, or nothing at all.
Certainly bears good investigation, but far too soon for conclusions (an I'm usually biased towards acting based on Precautionary Principle, but this just seems far too indirect to even make assumptions, let alone conclusions).
This is also an important problem - there is a lot of synthetic rubber particulate in waterways and oceans - a notable fraction of all microplastics.