The role of formaldehyde and formaldehyde releasers in contact allergy and contact dermatitis were outlined in results from a clinical review published in Contact Dermatitis. Study authors summarized the common uses of formaldehyde, the prevalence of skin sensitization to formaldehyde, the clinical outcomes of formaldehyde sensitization, and means of testing for formaldehyde allergy.

Common exposure sources for formaldehyde include food, cosmetics, pharmaceuticals, household detergents, medical devices, and industrial chemical products. Formaldehyde releasers comprise a group of approximately 40 compounds with a detachable formaldehyde moiety, which releases during decomposition. These releasers pose a risk similar to pure formaldehyde and are widely used in cosmetic, medical, and household product formulations. The 5 main releasers of formaldehyde are quaternium-15, diazolidinyl urea, DMDM hydantoin, imidazolidinyl urea, and 2-bromo-2-nitropropane-1,3-diol (bronopol). In Europe, the use of free formaldehyde and quaternium-15 in cosmetics is forbidden; in the United States, however, the use of these compounds is unregulated.

The estimated rates of sensitization to formaldehyde and formaldehyde releasers vary. In Europe, contact allergy to these products is estimated to affect between 1.5% and 2.5% of people, with rates stable to decreasing in recent years as a result of more stringent cosmetic regulations. In the United States, contact allergy rates are higher, with an estimated prevalence of approximately 8%, it was noted. Formaldehyde is a top allergen in the pediatric population and can be found in disposable diapers and wipes. As with adults, sensitization rates among children are lower in Europe compared to the United States (<1% vs 3%).


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Formaldehyde and its releasers are associated with both localized and widespread dermatitis. Exposure may also complicate atopic and stasis dermatitis or result in nummular dermatitis. Seborrheic-, rosacea- and impetigo-like dermatitis have also been identified as reactions to formaldehyde exposure. To appropriately diagnose formaldehyde sensitization, the investigators suggest that patch testing be performed with a 2% aqueous solution (0.60 mg/cm2). Although formaldehyde patch testing is often an adequate screen for sensitization to most releasers, separate patch tests may be relevant for bronopol and diazolidinyl urea. If sensitization to formaldehyde is detected, both formaldehyde and its releasers should be avoided. If a patient reacts to 1 or more releaser, that specific releaser should be avoided, although not necessarily formaldehyde itself.

Both consumers and professionals can become sensitized to formaldehyde. The decreasing rates of contact allergy in Europe underscore the utility of more stringent regulations for manufacturing which involves formaldehyde. Further research into the presence and effects of formaldehyde is warranted, the researchers wrote.

“[Formaldehyde] is not always declared on the product labels, and it has been identified as a hidden compound in many cosmetic products, and occasionally also in other consumer products,” study authors wrote. “This underscores the importance of chemical analyses of products and the utility of (chemical-based) spot test kits for identification of potential [formaldehyde] exposure.”

Disclosure: A study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 

Reference

Goossens A, Aerts O. Contact allergy to and allergic contact dermatitis from formaldehyde and formaldehyde releasers: a clinical review and update. Contact Dermatitis. 2022;87(1):20-27. doi:10.1111/cod.14089