Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are not contagious or life-threatening, but can be very uncomfortable. Contact dermatitis results from either exposure to allergens (allergic contact dermatitis), or irritants (irritant contact dermatitis). Allergic contact dermatitis involves a delayed type of hypersensitivity and previous exposure to an allergen to produce a reaction. Irritant contact dermatitis is the most common type and represents 80% of all cases. It is caused by prolonged exposure to irritants, leading to direct injury of the epidermal cells of the skin, which activates an immune response, resulting in an inflammatory cutaneous reaction. Phototoxic dermatitis occurs when the allergen or irritant is activated by sunlight. Diagnosis of allergic contact dermatitis can often be supported by patch testing. Epidemiology
Contact dermatitis constitutes 95% of all occupational skin disorders. There are few accurate statistics on the incidence and prevalence of contact dermatitis. The results of the few studies that have been undertaken cannot be compared because of methodological differences. Signs and symptoms
Contact dermatitis is a localized rash or irritation of the skin caused by contact with a foreign substance. Only the superficial regions of the skin are affected in contact dermatitis.
It is important to also note that chemicals sometimes have several different names, and do not always appear on labels.The distinction between the various types of contact dermatitis is based on a number of factors. The morphology of the tissues, the histology, and immunologic findings are all used in diagnosis of the form of the condition. However, as suggested previously, there is some confusion in the distinction of the different forms of contact dermatitis. Using histology on its own is insufficient, as these findings have been acknowledged not to distinguish, and even positive patch testing does not rule out the existence of an irritant form of dermatitis as well as an immunological one. Prevention
In an industrial setting the employer has a duty of care to its worker to provide the correct level of safety equipment to mitigate exposure to harmful irritants. This can take the form of protective clothing, gloves, or barrier cream, depending on the working environment. It is impossible to eliminate the complete exposure to harmful irritants but can be avoided using the multidimensional approach. The multidimensional approach includes eight basic elements to follow. They are:

Identification of possible cutaneous irritants and allergens
To avoid skin exposure, use appropriate control measures or chemical substitutes. Personal protection can be achieved by the use of protective clothes or barrier creams.