Formaldehyde: The insidious contact sensitizer

Acta Eruditorum

Abby Van Voorhees

Dr. Van Voorhees is the physician editor of Dermatology World. She interviews the author of a recent study each month.

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In this month’s Acta Eruditorum column, Physician Editor Abby S. Van Voorhees, MD, talks with Magnus Bruze, MD, about his recent Dermatitis article, “Formaldehyde: Contact allergen of the year.”

Dr. Van Voorhees: Why was formaldehyde chosen by the American Contact Dermatitis group as the contact allergen of 2015? How frequently is this the cause of contact dermatitis? Remind us of the scenarios where we want to be thinking about this agent being the culprit.

Dr. Bruze: Studies have shown that contact allergy (immunologically acquired hypersensitivity) to formaldehyde is more common than was previously believed. This additionally found formaldehyde allergy has been shown to be clinically relevant. A major problem with contact allergy to formaldehyde and allergic contact dermatitis from formaldehyde is that the history and clinical presentation of the dermatitis rarely points at formaldehyde as the cause of the dermatitis.

Dr. Van Voorhees: Hasn’t formaldehyde testing been part of standard contact dermatitis screenings for a while? Did experts feel that cases were being missed?

Dr. Bruze: Formaldehyde at various concentrations has for decades been a part of the standard contact dermatitis screening. The test concentration has been lowered a few times because of irritant test reactions. Actually, the reason is not the concentration but the dose of formaldehyde on the skin (concentration and volume of the aqueous preparation applied on a defined skin area). I have known this for many years and therefore patch tested with a defined volume at a higher formaldehyde concentration when handling patients where I have had a strong suspicion of formaldehyde allergy or when a patient has had a doubtful reaction to formaldehyde. In this way patients with a weak contact allergy have been found and the contact allergy subsequently has been shown to be clinically relevant.

Dr. Van Voorhees: In your report you recommend a change in the way formaldehyde is tested. Should the dose be changed? Do you recommend an alternative technique for its testing? Why is this recommended?

Dr. Bruze: With the previous concentration recommended, 1 percent, there was no volume of test solution recommended independent of test chambers used. The change now is that a double concentration, 2 percent, should be used provided that the recommended volume of the aqueous test preparation is used. For the Finn chamber technique with the small chamber with a diameter of 8 mm, 15 microliters is the recommended volume. To get the desired volume a micropipette must be used.[pagebreak]

Dr. Van Voorhees: Will these recommended changes cause any difficulties for patients, such as irritation?

Dr. Bruze: Any patch testing including testing with an empty test chamber may occasionally give an irritant test reaction. Based on our knowledge of the range of volumes applied when not using a micropipette for the application of the test solution onto the test unit, one will rather expect fewer irritant reactions when using the 2 percent solution and the recommended volume as compared to the old testing with the lower concentration without applying a defined volume.

Dr. Van Voorhees: Does your group feel that these recommendations should be applied to all screenings for formaldehyde sensitivity?

Dr. Bruze: Yes, definitely.

Dr. Van Voorhees: How do you recommend avoiding formaldehyde exposure?

Dr. Bruze: To avoid exposure to formaldehyde one has to know where it is present. It is usually known when formaldehyde is used in occupational applications. The presence of formaldehyde in cosmetics will be revealed by the labeling informing on whether any formaldehyde releaser has been used. However, small amounts of unlabeled formaldehyde may be present in cosmetics due to degradation of chemicals such as emulsifiers. Unfortunately, these low concentrations of unlabeled formaldehyde may be clinically relevant. This has been demonstrated in patients with formaldehyde allergy and irritant contact dermatitis when the use of a moisturizer with such a low concentration has caused a deterioration of the dermatitis.

Dr. Van Voorhees: How do you avoid an unintentional exposure to low concentrations of formaldehyde in cosmetics?

Dr. Bruze: When contact allergy to formaldehyde is diagnosed, the dermatologist should be able to advise the hypersensitive patient on cosmetics such as shampoos, liquid soaps, moisturizers, etc. without formaldehyde. Preferably, the national contact dermatitis societies should “provide lists” to the dermatologists with such cosmetics where the absence of formaldehyde is based on chemical analyses.

Dr. Bruze is professor in the department of occupational and environmental dermatology at Malmo University Hospital. His article appeared in the January/February 2015 issue of Dermatitis, (26(1): 3-6). doi: 10.1097/DER.0000000000000075.