So you want to sell that cookie you lasered/milled at the craft fair. Here are the facts that the FDA use when figuring out how much contamination your item can contain.
Caution, do not read while eating!
Being in the chemistry side of the Pharma industry I routinely look at FDA inspection notice actions for Pharma companies. Sometimes I look at the ones for the food side and you would not believe some of the things food suppliers get busted for.