Which of the following is the most common cause of metal allergy due to jewellery?

Ans. D. Nickel. (Ref Rook's Textbook of Dermatology, 8th/ pg. 26.30)# As a group, metals are the most common contact allergens. Nickel is the most common cause of metal allergy, followed by gold, chrome, cobalt and mercury. Allergic sensitivity to a metal usually is highly specific, but cross- sensitivity with other metals is common.# Nickel produces more cases of allergic contact dermatitis than all other metals combined. Erythematous and eczematous eruptions, often with lichenification, appear beneath earrings, bracelets, rings, wristwatches, clasps and blue- jean buttons. Nickel dermatitis frequently is seen on the earlobes. Piercing the earlobes with nickelplated instruments or wearing nickel-plated jewelry induces nickel sensitivity. Often the clasps in gold jewelry contain nickel. Sweat containing sodium chloride may combine with nickel to form nickel chloride. Therefore, prespiring profusely will affect the degree of nickel dermatitis.