Contact Dermatitis

Contact dermatitis is an inflammatory reaction of the skin that arises through skin contact with certain types of chemicals. There are two types: Allergic Contact Dermatitis and Irritant Contact Dermatitis.

Allergic Contact Dermatitis involves the immune system and is known as a Delayed Hypersensitivity reaction. It arises as a result of the exposed individual becoming sensitised to a specific chemical allergen. Subsequent exposure to that same allergen results in an inflammatory reaction, or dermatitis. Common contact allergens known to cause dermatitis include formaldehyde, epoxy resin and nickel.

Although there is not way to predict who will develop allergic contact dermatitis, there are a number of factors that can make an individual more predisposed to developing this condition. These include skin condition, chemical structure and allergen potency.

The problem with any allergy is that it can persist for life. Once sensitised, the only way to avoid the outbreak of symptoms is to avoid all contact with that specific chemical. In the workplace, this can be highly problematic because the level of exposure needed to trigger an outbreak of symptoms in a sensitised individual is usually very low. Therefore, the only option is to remove the affected worker from any work activities that involve that particular chemical allergen.

Irritant contact dermatitis does not involve the immune system. Instead direct exposure to a chemical irritant produces a local inflammatory reaction. (The irritant is able to penetrate the skin cells, cause damage which results in an inflammatory response.

Chemicals such as acids and alkalis (below corrosive strength) will cause inflammation as a result of a single exposure. However, there are other chemicals, such as detergents, soaps and even water that will give rise to a cumulative irritation. This is because multiple or prolonged skin contact is needed before the symptoms of dermatitis become evident.

As with allergic contact dermatitis, there are a number of extrinsic and intrinsic factors that contribute to the development of irritant contact dermatitis. These include atopy, age and region of skin exposed. In addition the nature of the chemical substance to which exposure occurs and circumstances of exposure also need to be considered.

HSE “Bad Hand Day” campaign has lots of additional information and some rather gruesome pictures of what occupational dermatitis can look like. In particular, check out the information regarding the choice and use of gloves.