[Skin reactivity in subjects sensitive to different concentrations of nickel, chromium and cobalt].

Patch tests with serial dilutions of nickel sulphate, potassium dichromate and cobalt chloride in petrolatum were performed on 124 nickel-sensitive, 64 chromium-sensitive, and 72 cobalt-sensitive subjects. The lowest eliciting patch test concentrations were as follows: nickel sulphate--0.005, potassium dichromate--0.0025, and cobalt chloride--0.005.