Contact urticaria from nickel and plastic additives (butylhydroxytoluene, oleylamide)

In two patients urticaria was elicited by contact with nickel-containing objects. Chamber-prick test with nickel sulfate 2.5% in pet. evoked a strong urticarial reaction in both patients. In one of the patients contact with plastic articles also provoked urticaria. A 20-min patch test with several articles of plastic (polyethylene and PVC) and with butylhydroxytoluene (BHT) 1% in ethanol elicited urticarial reactions. BHT is used as an antioxidant in plastic. Furthermore, open patch test with oleylamide (amide of oleic acid) 0.1% in ethanol elicited a strong urticarial reaction in 20 min. This chemical is used as a slipping agent in plastic.