Is the irritant benzalkonium chloride a contact allergen? A contribution to the ongoing debate from a clinical perspective

• Published in: Contact dermatitis 2008-06, Vol.58 (6), p.359-363
• Main Authors: Uter, Wolfgang, Lessmann, Holger, Geier, Johannes, Schnuch, Axel
• Format: Article
• Language: English
• Subjects: Adult; Aged; Allergens - adverse effects; Allergic diseases; benzalkonium chloride; Benzalkonium Compounds - adverse effects; Biological and medical sciences; CAS 8001-54-5; clinical epidemiology; contact allergy; Dermatitis, Allergic Contact - diagnosis; Dermatitis, Allergic Contact - epidemiology; Dermatitis, Allergic Contact - etiology; Dermatitis, Irritant - diagnosis; Dermatitis, Irritant - etiology; Disinfectants - adverse effects; False Positive Reactions; Female; Humans; Immunopathology; Male; Medical sciences; Middle Aged; Occupational Exposure - adverse effects; patch test; Patch Tests; Preservatives, Pharmaceutical - adverse effects; Prevalence; Reproducibility of Results; Retrospective Studies; Skin allergic diseases. Stinging insect allergies
• ISSN: 0105-1873; 1600-0536
• DOI: 10.1111/j.1600-0536.2008.01327.x

Background:  Benzalkonium chloride (BAC) is a well‐recognized irritant. However, doubts exist that it is also a contact allergen. Objective:  Analysis of clinical patch test data addressing the reaction profile and synchronous reproducibility of BAC 0.1% in petrolatum (pet.) and possible increases in risk of BAC contact allergy in certain (occupationally exposed) subgroups. Patients /Methods:  Data of 42 898 patients tested with BAC 0.1% in pet. in 3 different series (topical drugs, ophthalmics, and disinfectants) in the departments of the Information Network of Departments of Dermatology (http://www.ivdk.org) between 1996 and 2006 was analysed. Results:  Overall, morphologically ‘positive’ reactions were rare, 0.6–1.5%, with a total of 41 stronger positive reactions. Concordance, assessed in 3322 patients tested in duplicate, was low (kappa coefficient 0.15, 95% CI: 0–0.31). Positive test reactions were observed significantly more often in the disinfectants series compared with the 2 other series, indicating that suspected exposure to disinfectants may be associated with sensitization. However, variation of stronger BAC test positivity across potentially relevant (occupational) groups was non‐significant. Conclusion:  This analysis of routine clinical data and a number of previous reports add further, if weak, evidence to the notion that BAC is a contact allergen, albeit a very rare one.