The International Union for Conservation of Nature commissioned the first global assessment of 'primary' microplastics, meaning particles released directly into the environment as tiny fragments rather than from larger items breaking down.
It estimated that 0.8–2.5 million tonnes (central estimate 1.5 million tonnes) of primary microplastics enter the ocean each year. Synthetic textiles shed during washing contribute 35%, tyre abrasion 28%, city dust 24%, road markings 7%, marine coatings 3.7%, personal-care products 2% and plastic pellets 0.3%. Primary microplastics make up 15–31% of all plastic in the ocean.
The report matters because it shows microbead bans, while sensible, address only about 2% of the problem, while clothing and tyres are much bigger sources.
The figures are modelled from consumption and release rates, not measured at sea, and are now almost a decade old.