Explanation of First Aid Terms
(i) DERMATITIS
There are two types - irritant and allergic.
The irritant reaction occurs where the chemical damages the skin directly at the point of contact. The damage may not be immediately apparent, but if the exposure is repeated it may result in an accumulation of damage until the skin can no longer tolerate any further exposure. The result is that the skin can become inflamed, itchy and often a red rash with cracking and blistering appears. If the exposure is minor the skin will heal when the contact is removed. However extensive contact may cause more severe damage.
The allergic reaction involves an overreaction of the body’s immune system, which, once triggered, tends to be a long term or permanent effect (see Sensitisation). The symptoms only appear when there is exposure to the trigger chemical and once exposure is removed the symptoms recede as the body recovers. The onset of symptoms is usually very quick - seconds or minutes. The symptoms may be apparent over the whole body, which can manifest in a similar way to irritant reactions. It is not possible to determine in advance why a particular person may be affected as, in common with most allergic reactions; it is an individual intolerance to a particular material.
(ii) SENSITISATION
This is a process by which a person exhibits a reaction to a particular material but only after a period of repeated contact. Once the allergic reaction has been established then even a low level of brief repeat contact will trigger the reaction. The symptoms will usually appear as a rash of varying coverage, intensity and discomfort. The time period between first contact and subsequent development of sensitisation, causing the rash to appear, can vary from days to years.
This is a highly individual problem. Some workers will be able to handle so-called ‘sensitisers’ for years with no effect. Some will react almost immediately and others may only show the reaction after having handled the material for many weeks or months.
Sensitisation can occur through skin and respiratory contact.
(iii) CORROSIVE
Certain chemicals are classified as corrosive, which means that they damage or destroy living tissue on contact. Typically, the effect will be seen as redness and blistering of the skin.