What is it: FD&C dye
There are only seven chemical dyes that are permitted by the FDA to be used in food, drugs or cosmetics. Of these, Yellow #5 is a known irritant causing hives in one in 10,000 people and Red # is a carcinogen (this turns up in blush). FD&C dyes are derived from coal tar or petroleum. Both of these can contain trace elements, such as benzene and naphthalene (used in mothballs) and phenol that can be carcinogenic or irritants.
Some make up makers, such as Jane Iredale, are now going out of their way to avoid FD&Cs and substitute them with mineral pigments. Iredale doesn't use talc either and she adds in nice anti-oxidants such as pomegranate to products such as her loose powder.