500/day is frankly preposterous for the "average person". I cook very regularly for a family of three, and the most cutting I'm usually doing is cutting the ends off green beans. That's two cuts per bean pod, with maybe 75 pods. (And I'm usually cutting a few in one go.) That's an above-average day. It's nowhere close to 500. It's much closer to 100.

Also, it's not even clear what toxicity level there is for microplastics, if any. The article even points this out.