PORTLAND, Ore. (AP) — A Portland State University study found tiny pieces of plastic in the vast majority of razor clams and oysters sampled along the Oregon coast and noted that the primary source of contamination was from fibers used in synthetic textiles.

Those microscopic fibers can be shed by yoga pants, fleeces and other active wear made of synthetic textiles during a wash — up to 700,000 per load of laundry, according to the study, which was reported on Tuesday. Most of these fibers are in the wastewater from laundry machines that eventually winds up in the ocean.

The shellfish in question were plucked from 15 sites, from Clatsop in the north to Gold Beach near the California border, in 2017. Of the roughly 300 shellfish analyzed, all but two contained at least some microplastics.