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  Atopic eczema, irritant dermatitis and contact dermatitis
 
 
 

OCCUPATIONAL CONTACT DERMATITIS

Occupational contact dermatitis is caused entirely by external factors related to a person’s work environment. It is a delayed inflammatory reaction that occurs to people when their skin comes in direct contact with various sensitizing allergens and irritants present in their place of work.

People with occupational dermatitis belong to a wide variety of trades and professions and include beauticians, construction workers, cooks, farmers, medical personnel, printing industry workers, and food handlers. In most cases, occupational dermatitis affects the hands alone but may spread to the forearms. The face may be affected if air-borne agents are the cause. Triggers can include things like hair products, jewellery, cosmetics, cloth dyes, rubber, leather and cement.

The development of this condition is often abetted by some pre-existing skin conditions, such as, atopic diseases.

Types of occupational dermatitis

Occupational dermatitis covers a range of delayed skin reactions but mainly include irritant, allergic, urticaria and photo contact dermatitis

Irritant contact dermatitis

This type of occupational dermatitis accounts for about 80% of contact dermatitis cases. It occurs mostly on the hands, where the skin, due to chronic exposure to some cleaning agent or sensitizing irritants, produces a localized inflammation. There are two types of irritants, classified as immediate and cumulative irritants. The immediate irritants are strong acids or alkalis which produce reactions within minutes or hours. Cumulative irritants, such as, petroleum products and weak acids or alkalis work slowly so that the worker only becomes aware days, weeks or months after repeated exposures.

It is common among people engaged in, what is called, the “wet work” occupations, such as, cleaners, hairdressers, health care personnel, cooks and food handlers. These irritants work by entering and impairing the skin’s natural protective barriers, as a result the skin progressively becomes dry, scaly and cracked leading to eczematous dermatitis. Chemicals, such as, solvents, detergents, cutting oils and urine ammonia in nappies are common triggers. The condition often occurs where the skin is thinnest, so the common sites are finger webs and back of the hands rather than the palms.

Allergic contact dermatitis

Allergic contact dermatitis is an immune system mediated condition that develops in stages, after prolonged exposure to an allergen at the workplace. The first stage is the sensitization stage when allergens enter the outer layer of the skin. No skin reaction is visible at this stage. The rashes take about 48 hours to appear and are sharply defined at the place of exposure or contact. In some cases, rashes may take several weeks to appear. The rashes appear when the sensitized worker is later re-exposed to the allergens which react with the skin’s protein and weaken the immune system of the skin. This results in itching, pain, redness, swelling and blisters on the skin.

The inflammation in allergic contact dermatitis is normally confined to the region of contact or exposure with the allergen but in severe cases it may be spread wide on the body. The condition is usually at its worst in 3 or 4 days after the first exposure. While treatment can improve the condition in about a week, the allergic sensitization may remain with the person for life. Without treatment over time and repeated exposure the skin may thicken.

The common triggers for this allergy are common metals, especially nickel; dyes, rubber products, plant allergens and cosmetics.

Contact urticaria

Contact urticaria is different from other forms of occupational contact dermatitis in its clinical manifestations, its time sequence, the triggering agents, and mechanism of action. The clinical reaction appears on the site of direct contact, usually the fingers, but consists of small itching wheals, emerging within 10-20 minutes after contact and quickly disappearing. The triggering agents may be latex rubber in gloves, animal proteins or other foodstuffs. The patients are often health care personnel, chefs and workers in the meat and fish industry.

The responsible allergens are high-molecular weight, complete antigens that are normally not absorbed by the skin. Therefore, a damaged or infected skin barrier system is needed to facilitate their entry. Contact urticaria patients usually have an atopic condition.

Photo contact dermatitis

Photo contact dermatitis is caused by the action of ultraviolet light on a skin, which has certain sensitizing agents. The implication being that mere presence of the sensitizer will not produce contact dermatitis. People will not get this condition if they stay indoors. Exposure to ultraviolet radiation is also necessary along with the sensitizing agent before photo contact dermatitis develops. That is why photo contact dermatitis always occurs on the light exposed parts of the body. Common sensitizers are found in plants seen almost everywhere, such as, parsnip, fennel, carrot and celery. Photocontact dermatitis is therefore seen sometimes among the farming communities.

Treatment

Avoiding further exposure is alone a major part of the treatment. Further drug treatment approaches are no different from those used in contact dermatitis.