Patterns of positive patch test reactions to formaldehyde and formaldehyde releasers at the <scp>F</scp>innish <scp>I</scp>nstitute of <scp>O</scp>ccupational <scp>H</scp>ealth from <scp>2007</scp> to <scp>2020</scp>
Kristiina Aalto‐Korte, Maria Pesonen
Abstract
BACKGROUND: Formaldehyde is an important contact sensitizer. Formaldehyde releasing substances induce positive reactions in formaldehyde-allergic patients, but there are also reactions independent of formaldehyde allergy. In an earlier study, stronger formaldehyde reactions led to more positive reactions to quaternium-15. OBJECTIVES: To analyze patterns of positive patch test reactions to formaldehyde and different formaldehyde releasers. METHODS: Patch test files of 1497 patients investigated during the period November 2007-August 2020 were retrospectively reviewed for positive reactions to formaldehyde and its releasers. During the study period, almost all (≥99.3%) patients were tested with a formaldehyde dilution series and six formaldehyde releasers. RESULTS: Ninety-three patients tested positive to formaldehyde; 80% of these had positive reactions to at least one formaldehyde releaser, most often benzylhemiformal. There were only nine independent contact allergies to formaldehyde releasers. There were only two reactions to 2-bromo-2-nitropropane-1,3-diol and they occurred in formaldehyde-negative patients. In patients with extreme (+++) reactions to formaldehyde, concomitant positive reactions to any of the other 11 investigated formaldehyde releasers were more common than in patients with milder formaldehyde reactions. CONCLUSIONS: Strong formaldehyde reactions were associated with positive reactions to formaldehyde releasers.