OBUHSN23 Appendix 2

Definitions and information on occupational skin diseases

Contact dermatitis – definition

The commonest reaction of the skin to penetration of the barrier layer by a substance on its surface is an inflammation referred to as eczema. The main signs of this condition are redness, swelling, blistering, flaking and cracking of the skin. The main symptom is itching. The type of eczema caused by contact with substances is called contact dermatitis.

It is important to make an accurate diagnosis of this condition as non-contact dermatitis and other skin conditions such as ringworm or psoriasis can result in similar signs and symptoms.

Irritants and sensitisers

Substances capable of causing contact dermatitis can be divided into two groups, irritants and sensitisers (or allergens)

Definitions

Irritant: a skin irritant is a non-infective substance that can cause cell damage if applied to the skin for sufficient time and in sufficient concentration. Even water can become an irritant.

Sensitiser : a sensitiser or allergen is a substance that can cause an allergic contact dermatitis. Once the substance has penetrated the skin’s outer protective layer, it sets off a chain of immunological events after which time further skin contact with the same sensitiser causes allergic contact dermatitis. There is a very wide individual variation in susceptibility to sensitisation among the human population that reflects the differences in allergic response to a particular substance.

Since there is not visual distinction between irritant and allergic contact dermatitis, it is important to refer anyone suffering with signs and symptoms of skin problems to Occupational Health in order to accurately determine the cause. Other less common skin complaints can also have an occupational cause such as oil acne, contact urticaria (hives), ulceration and less commonly some skin cancers.