"Each year, more than a half-million metric tons of microfibers — the equivalent of 50 billion plastic water bottles — enter the ocean from the washing of synthetic textiles..."

"... according to the International Union for Conservation of Nature and Natural Resources, a Switzerland-based group that counts governments, nonprofits and charities among its members. While all clothing sheds fibers when washed, synthetic particles — unlike wool and cotton — don't biodegrade. Most conventional washing-machine filters aren't designed to trap such tiny particles.... Microplastics have turned up in seafood, drinking water, beer, honey and sugar, according to studies, but the impact on human health is unclear...."

From "The Tiny Plastics in Your Clothes Are Becoming a Big Problem" (Wall Street Journal).