Minimum eliciting levels of nickel have been estimated in 25 nickel-sensitive subjects, and of chromium in 14 chromium-sensitive subjects by patch tests with aqueous solutions of the respective metals. The minimum level of each metal required to provoke a patch test reaction was considerably greater than that found in fabric washing powder solutions and was in the majority of patients tested of the order of 112 ppm nickel (0.05% nickel sulphate) or 885 ppm hexavalent chromium (0.25% potassium dichromate). One nickel-sensitive subject and one chromium-sensitive subject reacted to 1 ppm of the respective metal. Fabric washing powder did not significantly alter the patch test reaction to nickel sulphate or provoke reactions in nickel- or chromium-sensitive subjects. EDTA significantly reduced the number and severity of patch test reactions to nickel sulphate but not those to potassium dichromate or trivalent chromium.
Chlorides Chromates