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CONTACT DERMATITIS
About 2% of the population will be affected by some form of contact dermatitis. Occupational skin disorders account for up to a third of all occupational problems and the majority of these are contact dermatitis.
Contact dermatitis is the result of:
an allergic reaction to certain substances thus causing allergic contact dermatitis.
or
Exposure to/or contact with an irritant causing irritant contact dermatitis.
Both types of reaction are usually as a response to constant, long-term exposure to a “trigger” factor that is cumulative. This constant exposure causes cell-mediated immune reactions and over time the body develops a “hypersensitivity” to the “trigger” factor. The conditionoccurs in both industrial and domestic environments. However, the reactions that occur in industrial environments can be more sustaining and more difficult to control.
Band Aid Contact Dermatitis
It should be noted that the initial site of eruption will only provide an indicator to the likely “trigger” factor. Confusion or lack of ability to pinpoint a “trigger” may occur after the subsequent spread of the dermatitis to other body sites. The initial site of dermatitis can also be a result of the transfer of the trigger factor to the affected area e.g nickel can be spread/transferred from hands to the eyes by rubbing the eyes. The resulting dermatitis on the eye may be wrongly attributed to eyeshadow whereas in reality the cause was the reaction to the trigger transfer from the hands after handling coins. The hands may not have reacted to the nickle, hence the confusion.
ALLERGIC CONTACT DERMATITIS
This condition is usually caused by chemicals used in dyes, cosmetics, industrial dyes and industrial processing and occasionally by certain medications.
It is a delayed hypersensitivity reaction resulting from sensitized lymphocytes. As the body is exposed to an allergen, T-lymphocytes within the blood are sensitized. They then divide & multiply to form “effector” lymphocytes. This may be a gradual process after many different exposures over many days, months or years. Alternatively, the sensitization can come after a first exposure episode (it is important to note that the appearance of lesions may not occur at this time).
Symptoms of allergic contact dermatitis may appear after a few hours or can take up to several days to emerge. Often there is a “burning” sensation of the skin with a prickly, itchy feeling in the areas directly exposed to the allergen. Clusters of small, fluid filled blisters on a reddened background will then begin to appear. Damage to the tissue is usually greatest two or three days after exposure.
Once this process is set in place, subsequent contact with an allergen in any area of skin, will trigger the allergic dermatitis.