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®.

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® 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®, 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® 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.