Most common metal in contact allergic dermatitis is-

Ans. is 4d' i.e., Nickel Contact dermatitiso Contact dermatitis is localized rash or irritation of skin caused by contact with a foreign substance. Contact dermatitis is a localized disease, i.e., lesion occurs at the site of contact. However, in sever cases, the lesions may extend outside the contact area or it may become generalized (referred to as id eruption).o Contact dermatitis is mainly of two types : -Irritant contact dermatitisDue to direct irritant action of the material e.g. Solvents, Alkalis, Detergents. Most common sites are hands & forearms.Allergic contact dermatisIt is due to delayed hypersensitivity (type IV hypersensitivity) to a particular antigen in a sensitized individual. The most common allergens causing allergic contact dermatitis are pollen and metals : -Parthenium (Congress grass)Nickel