Differences in contents of organochlorine impurities do not influence responses to patch testing with M ajantol®

Summary Background Majantol® [2,2‐dimethyl‐3‐(3‐methylphenyl)propan‐1‐ol; CAS no. 103694‐68‐4] has been identified as a contact allergen in humans, despite negative animal tests. Hence impurities, specifically organochlorines, in M ajantol® might have been the reason for positive patch test reactions in the past. Objectives To assess elicitation via patch testing with a standard market‐quality version of M ajantol® (‘normal’) with a normal content of organochlorine impurities, as compared with an ultra‐purified version of M ajantol® (‘pure’), without detectable organochlorine impurities. Methods Between 1 O ctober 2013 and 31 D ecember 2014, two different M ajantol® patch test preparations of the above‐mentioned quality were tested 5% pet. in parallel in the ‘monitor series’, that is, together with the baseline series, in 8005 consecutive patients from 33 departments of dermatology of the I nformation N etwork of D epartments of D ermatology ( IVDK ). Results Fifty‐three of 7740 [0.69% (95% CI : 0.51–0.87)] patch tested patients reacted to at least one M ajantol® preparation. The majority (n = 32) (60.4%) reacted to both preparations, 13 (24.5%) reacted to the ‘normal’ version only, and 8 (15.1%) reacted to the ‘pure’ version only. There was good concordance between results [ C ohen's kappa 0.75 (95% CI : 0.65–0.85)], and there was no significant difference in frequency or intensity between the two preparations. More doubtful or irritant reactions than positive reactions were observed, and> 80% of all positive reactions were weak positive. Conclusion Organochlorine impurities are very probably not the cause of allergic reactions to M ajantol®.