How much marijuana is really in that pot brownie? Chocolate can throw off potency tests so labels aren't always accurate, and now scientists are trying to figure out why. In states where marijuana is legal, pot comes in cookies, mints, gummies, protein bars — even pretzels. These commercial products are...

How much marijuana is really in that pot brownie? Chocolate can throw off potency tests so labels aren't always accurate, and now scientists are trying to figure out why. In states where marijuana is legal, pot comes in cookies, mints, gummies, protein bars — even pretzels. These commercial products are...