Contact dermatitis is a common problem among workers and constitutes approximately 5.7 million physician visits per year. All age groups are affected, and there is a slight female predominance as reflected in patients seen for diagnostic patch testing. There are more than 100,000 chemicals in the environment today. Almost any substance can be an irritant, depending on the exposure circumstances. Further, over 2,800 substances have been alleged to be contact allergens.
Contact dermatitis is an altered state of skin reactivity induced by exposure to an external agent.
Substances which produce this condition after single or multiple exposures may be irritant or allergic in nature and will often present as an inflammatory process. Direct tissue damage results from contact with irritants. Following contact with strong irritants the reaction is immediate with blistering and pain, resembling a burn. The generic term for both of these conditions is contact dermatitis. Tissue damage by allergic substances is mediated through immunologic mechanisms.