Determination of formaldehyde in formaldehyde-releaser patch test preparations

Background: Positive patch test reactions to formaldehyde-releasers in patients co-reacting to formaldehyde are often ascribed to formaldehyde allergy. However, the formaldehyde content of patch test materials has not been investigated. Objectives: To demonstrate and quantify free formaldehyde in commercial patch test materials and in prepared aqueous solutions of formaldehyde releasers. Materials: Free formaldehyde was measured by 13C NMR Spectroscopy in (i) all formaldehyde-releasers in water available from Chemotechnique® and Brial®, (ii) 5 releasers in petrolatum, (iii) 12 prepared aqueous solutions of formaldehyde-releasers and (iv) water that had been in contact with petrolatum test samples. Results: In none of the five petrolatum test substances was free formaldehyde found. In all nine commercial aqueous patch test substances and 9 of the 12 prepared solutions, free formaldehyde was demonstrated with concentrations ranging from 0.019% to 0.37% (detection limit 0.01%). Contact of the petrolatum test samples with water resulted in the release of formaldehyde. Conclusions: Most aqueous solutions of formaldehyde-releasers contain free formaldehyde. Petrolatum-based patch test materials with formaldehyde-releasers do not contain free formaldehyde, but probably start releasing it upon contact with water. Therefore, in future studies, determination of free and releasable formaldehyde may be preferable. © 2010 John Wiley & Sons A/S.