Formaldehyde and formaldehyde-releasers

Formaldehyde is a ubiquitous and important allergen. Contact allergy to formaldehyde occurs frequently in women with hand dermatitis. Sensitization may also be caused by occupational exposure to formaldehyde, especially in metalworkers, nurses, other (para)medical professionals, and cosmetologists. Formaldehyde is widely distributed in the environment and is difficult to avoid completely. Thus, even in patients actively trying to avoid products containing formaldehyde, the dermatitis will infrequently heal completely and permanently. Formaldehyde-releasers are chemicals, which release formaldehyde as a result of decomposition and/or chemicals synthesized from formaldehyde that may still contain residues of free formaldehyde. There are over 30 formaldehyde-releasers with a wide array of applications; most are used as preservatives in cosmetics; as antimicrobials in metalworking fluids, paint, lacquers, and varnishes; or as durable press chemical finishes in textiles. Positive patch tests to formaldehyde-releasers are often accompanied by concomitant reactions to formaldehyde; in these cases, the patch test to the releaser may be the result of an allergic reaction to the formaldehyde which is present in or released by the donor test material. For most releasers, co-reactivity to formaldehyde is >50%. There is very little published information on the relevance of observed positive patch test reactions to formaldehyde-releasers. Most reactions to releasers used in metalworking fluids appear not to be relevant with the exception of N, N′-Methylenebis(5-methyloxazolidine). The lack of relevance of reactions to the Bioban ® range of antimicrobials may partly be due to irritancy, leading to false-positive reactions. None of the formaldehyde-releasers are important causes of occupational allergic contact dermatitis. The presence of formaldehyde-releasers as durable press chemical finishes in clothes appears to be safe for consumers.