Yeah, microplastics seem to be systemic. I don't know that we actually have good data on this, but many sources claim that most microplastics are from polyester (a plastic) clothing and industrial nylon fishing nets. If true then wearing and washing a tacky shirt could be more hazardous that drinking from tons of plastic bottles and that would make such questions hard to ask in a predictive manner.

That doesnt say anything about accuracy or predicative power.