Abstract

Background

Preservatives such as formaldehyde and formaldehyde‐releasers are common causes of contact allergy.

Objectives

To examine trends in contact allergy to formaldehyde and formaldehyde‐releasers in patch tested patients in Denmark over a 10‐year period (2007‐2016), and to investigate relevant sources of formaldehyde among the patients.

Methods

A cross‐sectional registry studyhttps://onlinelibrary.wiley.com/doi/10.1111/cod.13052 on patch test data from patients tested with formaldehyde and formaldehyde‐releasers (N = 8463) was performed. The presence of released formaldehyde in products from formaldehyde‐allergic patients was identified with chemical analyses (chromotropic acid or acetylacetone test).

Results

The prevalence of contact allergy to formaldehyde 1% was 1.5%, and ranged between 0.97% and 2.3%, with a decreasing trend in this 10‐year period. Contact allergy to formaldehyde 2% was found in 2.4%, and no significant trend was observed. Quaternium‐15 was the formaldehyde‐releaser most often positive (0.86%). Patients allergic to formaldehyde often had simultaneous positive patch test reactions to formaldehyde‐releasers (36%). Almost 63% of the patients with formaldehyde allergy used products that released formaldehyde; cosmetics were the most common sources.

Conclusions

Although contact allergy to formaldehyde 1% decreased in this 10‐year time period, contact allergies to formaldehyde and formaldehyde‐releasers overall remain frequent in patients. In most cases, formaldehyde‐allergic patients are exposed to ≥1 products containing formaldehyde. Improved regulation on permitted amounts of free formaldehyde in cosmetics is still warranted, including direct labelling of formaldehyde when it is present in small but relevant amounts.

Source