Patch testing with methyldibromoglutaronitrile in a localized population in the United States

in Europe, methyldibromoglutaronitrile (MDGN) was banned because of excessive rates of contact allergy. However, it is unclear whether the concentrations used for testing MDGN are optimal, as different groups have used varying concentrations with quite different rates of positive reactions.

to report patch-test results with MDGN in a localized US population, to compare these results with those of other studies, and to evaluate any association between contact allergy to MDGN and atopic dermatitis.

a retrospective analysis of 1,753 patients tested with various concentrations of MDGN was conducted.

Four percent (4.0%) of patients had positive reactions to MDGN, of which 1.2% were ++/+++ reactions and 2.8% were + reactions. Among patients with ++/+++ reactions, 9.5% had a reaction of definite relevance; of patients with + reactions, only 2.0% had a reaction of definite relevance. Irritant reactions were had by 3.2% of patients; none of these were relevant. The North American Contact Dermatitis Group had a positive reaction rate of 6.2%; European groups had rates of 1.6 to 5.0%. No significant association was found between atopic dermatitis and positive patch-test reactions to MDGN.

owing to the number of irritant reactions observed, we suspect that many reactions to MDGN are falsely positive, underscoring the importance of careful interpretation of reactions less than or equal to +.