You can read the measurements in "Importance of Water-Volume on the Release of Microplastic Fibers from Laundry" by the team at the university of Newcastle : https://pubs.acs.org/doi/suppl/10.1021/acs.est.9b03022/suppl...

Edit: the publication of the full article seem to be under embargo (https://eprints.ncl.ac.uk/259968)