This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Skin
Which component of cement causes allergic contact dermatitis?? 
Select and explain. 
A. Cobalt, B. Nickel, C. Iron, D. Chromium
D: Chromium
Answer: D: Chromium 
Explanation: Ans : D: ChromiumMost common allergen is hexavalent chromium salts.Allergic contact dermatitis more than irritant contact dermatitis.Level of exposure needed for allergic contact dermatitis 100-400 nglcm2.Taarate, glycine, silicone, dapsone, ferrous sulphate causes conversion from chromium (VI) to chromium (III), which is less allergenic.