When is an Allergen Not an Allergen? Combating Misinformation about Parabens

Allergic contact dermatitis (ACD) affects more than 14 million people in the United States with an estimated economic burden of $3 billion per year.

The American Contact Dermatitis Society (ACDS) designates an Allergen of the Year annually to promote public awareness of the nominated allergen. The chosen allergen usually has the most significant clinical effects, is underrecognized, has a novel cause of ACD, or has become obsolete.

For 2019, the ACDS flipped its approach and selected parabens as the “Nonallergen” of the Year. The choice, announced in 2018, was made to clear some of the misconceptions about parabens among consumers and to increase awareness of the low rate of associated ACD .

The 4 most common parabens used are methylparaben, ethylparaben, propylparaben and butylparaben. Parabens are commonly used as preservatives in cosmetics, dermatological topical preparations, oral and parenteral medications, and in food products.

In the United States, parabens are allowed in cosmetics at concentrations up to 0.4% used alone; up to 0.8% when used as combination parabens; in medications at no more than 0.1%; and in food products at 0-10mg/kg of body weight. Parabens are metabolized to a water-soluble metabolite 4-hydroxybenzoic acid and eliminated in the urine. They have excellent coverage against fungi and gram-positive bacteria. Parabens are chemically inert, have no odor or taste and have high stability making it an ideal preservative.

Paraben use is not without controversy. Parabens have been reported on for unsubstantiated claims of endocrine disruption and an alleged association with breast cancer. Parabens have a chemical structure similar to estrogen and theoretically, they can mimic its effects. Data showing estrogenic effects of parabens are confined to in vitro or animal studies. In vitro studies have shown that parabens’ estrogenic potency is very weak. Parabens are 10,000-fold less potent than 17β-estradiol9—the major female steroid hormone—and has a maximum potency of 1/4000 that of estrogen.

The controversy regarding parabens and breast cancer has been fueled by the presence of parabens in human breast tumors, but parabens are widely used and present in several tissues. There are no studies that demonstrate that parabens cause harmful effects in humans. Based on available scientific data, the FDA has classified parabens as “generally regarded as safe” since the 1970s.

Retail health care providers are likely to field questions regarding paraben use and its safety. They have to remind patients that parabens are noncarcinogenic, nontoxic, used in low concentrations in cosmetics, excreted in the urine, and do not accumulate in the body. Patients must be made aware that “natural” does not always mean safe.

Without the use of preservatives, cosmetics, pharmaceuticals and food products can become contaminated with mold bacteria and fungi and increase risk of infections. Parabens have a low rate of associated ACD at 0.6% positive reaction rate when patch testing with 12% paraben mix.

Reference

Fransway AF, Fransway PJ, Belsito DV, et al. Parabens. Dermat Contact Atopic Occup Drug. 2019;30(1):3-31. doi:10.1097/DER.0000000000000429