Under the Federal Food, Drug, and Cosmetic Act, it is illegal to market an adulterated cosmetic in interstate commerce [21 U.S.C. 331(a)]. Under the law, one of the ways in which a cosmetic can become adulterated is if « it contains a poisonous or deleterious substance that may render the product injurious to users under the conditions of use prescribed in the labeling thereof, or under such conditions of use as are customary or usual » [21 U.S.C. 361(a)]. Such a « poisonous or deleterious substance » may include microbial contamination.
FDA issued Warning Letters to the follow firms, citing cosmetic products as adulterated due to microbial contamination posing a potential health risk for the uses recommended in the labeling: