Establishing aluminium contact allergy

Background. Traditionally, contact allergy to aluminium has been established by patch testing with aluminium chloride hexahydrate in petrolatum at 2.0% and an empty Finn Chamber (R). Objectives. The aim of this study was to investigate different aluminium test preparations regarding an optimal compound and an optimal test concentration. Methods. Six different aluminium compounds and an empty Finn Chamber (R) were used to patch test 21 patients with aluminium contact allergy. Aluminium chloride hexahydrate in saline was used for intracutaneous injection of 19 patients. Results. One test preparation, aluminium lactate 2.4%, was found to show significantly more positive patch test reactions than aluminium chloride hexahydrate 2.0% (p = 0.03). Aluminium chloride hexahydrate at 10.0% pet. gave the highest number of positive reactions to aluminium [14/21 (67%)]. No positive reactions were noted to an empty Finn Chamber (R), and 3 of 19 (16%) patients reacted positively to the intradermal test. Conclusions. The results of this study indicate that patch testing with aluminium chloride hexahydrate 2.0%, with an empty Finn Chamber (R) and the intradermal test with the salt and doses used are insufficient methods to detect contact allergy to aluminium. Aluminium chloride hexahydrate at 10.0% gave the highest number of positive reactions to aluminium.