The last two claims for special populations are non-comedogenic and non-acnegenic. These claims are aimed at individuals who develop acne in response to the facial use of skin care products and cosmetics. Non-comedogenic refers to the testing of products to determine that they do not produce blackheads, known as open comedones, or whiteheads, known as closed comedones, after wearing. Comedogenicity was a much greater problem when petrolatum was contaminated with tar, a known comedogen. Presently, comedogenicity is not a great problem, except in the ethnic hair care market where comedogenic vegetable oils, such as olive oil, are used in pomades to moisturize the hair.
Testing must be done to substantiate the non-comedogenic claim. In the past, comedogenicity was assessed in the rabbit ear assay by applying the final formulation inside a rabbit ear and then visually assessing the presence or absence of comedones. This test was not felt to have much human validity and animal testing has fallen out of favor; thus, the rabbit ear assay has given way to testing on human volunteers. Typically, the final formulation for testing is applied to the upper back in persons capable of forming comedones on the upper back daily for 14 days. A positive control, in the form of tar, is applied, and a negative control, in the form of pure petroleum jelly, is also used. The comedones are extracted from the upper back with cyanoacrylate glue placed on a microscope slide. Any increase in comedone formation following the 14-day exposure to the final cosmetic formulation is considered comedogenic.
The non-acnegenic claim is much different. It implies that the finished product does not produce true acne, which is identified as red bumps, known as papules, or pus bumps, known as pustules. It takes much longer for acne to develop from product use, typically about four weeks. There is no standard test done for acnegenicity, except for use testing. Volunteers use the product as intended for one month and are examined for the presence of papules and pustules. Yet, there are a number of individuals who will develop tiny perifollicular papules and pustules within 48 hours of wearing a skin care product or cosmetic. Is this acne? The answer is no. True acne cannot develop in 48 hours. In my opinion, this is perifollicular irritant contact dermatitis. It looks much like acne, but the presence of lesions at the follicular ostia and the rapid onset lead to the diagnosis of perifollicular contact dermatitis. This problem is best avoided by minimizing the presence of irritants in the formulation as previously discussed.
Formulating for special populations is indeed a challenge. There are unique dermatologic reaction patterns that must be considered. Failure to consider these reaction patterns could result in a product that is not globally acceptable. The globalization of the cosmetics industry means that skin care and cosmetic products must be suitable for both sexes, all ages, all skin types, all ethnic groups, all skin colors, etc. Understanding the unique needs of all world populations is vital to success.