Results of routine patch testing of 542 patients in Saskatoon, Canada.

542 patients (330 women, 212 men) with suspected allergic contact dermatitis were patch tested to standard series allergens between January 1983 and June 1987. Positive reactions were most frequently seen with nickel (17.4%), ethylenediamine (8.7%), formaldehyde (7.4%), colophony (7.0%), potassium dichromate (6.1%) and neomycin (5.7%). Patients with dermatitis involving the legs were significantly more likely to be allergic to ethylenediamine (p = 0.01) and benzocaine (p = 0.04) than those with dermatitis not involving the legs. Neomycin allergy was not associated with dermatitis involving the legs. Patients allergic to ethylenediamine were significantly more likely to be allergic to neomycin than patients not allergic to ethylenediamine (p = 0.002).