The term substantial evidence, coined by the US Food and Drug Administration (FDA) as part of the Federal Food, Drug and Cosmetic Act, applies mostly to new drug development, but also to products that are already approved. Although it is practically applied to drugs, it is important for the personal care industry to understand its rationale, especially since cosmetic products are becoming more sophisticated. Moreover, the same approach might be used when a claim issue regarding a personal care product arises and the FDA must make a judgment.
When issuing warning letters to manufacturers that request substantial evidence, the FDA is asking for evidence to support all the advertising claims made, including but not limited to comparative claims. In reference to this term, the agency is not referring to the amount of evidence generated, nor to the quantity of persuasive, competent or reliable evidence. Instead, it is referring to the term in its technical sense, i.e., supportive data that will lead to a significant scientific agreement. The Federal Food, Drug and Cosmetic (FD&C) Act defines substantial evidence as “evidence consisting of adequate and well-controlled investigations, including clinical investigations, by experts qualified by scientific training and experience to evaluate the effectiveness of the drug involved, on the basis of which it could fairly and responsively be conducted by such experts ... .”
This definition, as noted, is applied to drugs. Considering cosmetics, the manufacturer is not required to generate or submit information to the FDA regarding the biological effect of the product; therefore, there are not clear guidelines with regard to the substantiation of claims made for cosmetics. In fact, cosmetic products, by definition, should not generate any biological effects. If safety issues arise with a cosmetic product, the FDA can order the cessation of distribution of a misbranded or adulterated cosmetic product with a court order, or require companies to place warning labels on their products. However, due to the lack of FDA-filed safety information, and without clear evidence of acute injury, the FDA is not able to enforce warning labels or issue court orders.
As a service to manufacturers and to the general public, the FDA issued the following cautionary statement on its Web site on April 25, 2006: “Be aware that promoting a product with claims that it treats or prevents disease or otherwise affects the structure or any function of the body may cause the product to be considered a drug. The FDA has an Import Alert in effect for cosmetics labeled with drug claims.”