Occupational Dermatology Research and Education Centre
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Occupational Dermatology Research and Education Centre |
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Contact Dermatitis |
What is dermatitis?Dermatitis means inflammation of the skin. There are two causes of dermatitis, one is endogenous (meaning from inside the body), and comes from an inbuilt tendency to develop skin problems, where the term "eczema" is usually used.The second cause of dermatitis is exogenous (meaning outside the body), from substances contacting the skin and is known as "contact dermatitis". Sometimes doctors use the terms "eczema" and "dermatitis" to mean the same thing and this can be confusing! 
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Contact dermatitisContact dermatitis is a skin condition caused by external factors reacting on the skin. Not surprisingly, in occupational cases of contact dermatitis, the most common area involved is the hands, although other areas may be affected, such as other exposed skin (arms, face, neck, legs), and also other areas such as the feet. |
Types of contact dermatitisIrritant Contact Dermatitis:
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Irritant contact dermatitisWhat is it?Our skin has a natural protective barrier, and if this barrier is damaged by soaps, detergents, chemicals, or even water, the skin can become dry and flaky. This eventually progresses and may become inflamed (red), sore and cracked. Irritant contact dermatitis often starts in the web spaces between the fingers. Soap and other irritant substances often build up there, because of inadequate rinsing and drying, causing the skin to dry out more quickly. Frequent wetting and drying of the skin can therefore be damaging.
People who have had eczema, asthma or hayfever during their life, or have a strong family history of these conditions, may have more 'sensitive' skin. They are more likely to develop irritant contact dermatitis, some studies say as much as 4 times more likely. Even if a person only had eczema as a baby, they are still more likely to develop irritant contact dermatitis. Often people are unaware that they had childhood eczema, so it's a good idea to check with parents. It would be preferable to choose a career that did not include a lot of 'wet' work, or at the very least, take precautions to protect the skin right from the beginning. Interesting facts: The damage to the skin by soaps, detergents, chemicals, and water take some time to build up. Therefore the skin can take many months to heal, even once it appears to have returned to normal. This is why it is so important to protect the skin before signs of damage occur. Once skin irritants have damaged the skin barrier, allergic contact dermatitis is more likely to develop. With loss of the protective barrier, chemicals of a certain molecular shape and size may more readily penetrate into the skin and cause an allergic reaction to develop. This is often seen in hairdressers, who may initially develop irritant contact dermatitis when they commence wet work, but this is often followed by the development of allergic contact dermatitis to hairdressing chemicals such as dyes, bleach or perm solutions. Cleaners often start work without using gloves, but start wearing them after their skin has become damaged, only to develop allergies to the rubber in the gloves. People who work with cement may initially be irritated by cement dust, but may later develop a specific allergy to chromate, which is found in cement. |
Treatment and ongoing prevention of Irritant Contact Dermatitis:AwarenessIt is very important that people with a background of eczema, hand eczema, or childhood eczema, are aware that they have an increased risk of developing irritant contact dermatitis. They can then take precautions to protect and look after their skin right from the beginning of their job or career. Avoidance of skin irritants Where possible, try to reduce exposure to skin irritants, both the number of times and the amount. If chemicals are spilled onto the skin or clothing, it is very important to wash it off thoroughly and change clothes as soon as possible. Assessment of the workplace may be necessary to identify all skin irritants Substitution of skin irritants Substitution of a known hazardous chemical with a less harmful substance, is an important principle of occupational health and safety. Protection of the skin Wearing of gloves is important to protect the skin. Different gloves may be required for different duties, for example:
Gloves should be removed and/or changed regularly to minimise sweating, which can also be irritating to the skin. Protective clothing should also be worn when appropriate, for example: aprons, gauntlets (special protective forearm sleeves), splash masks, boots, or suits, may be required for particular jobs. Even simply wearing long sleeved 'T' shirts and trousers might be helpful. Skin care
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Allergic Contact DermatitisWhat is it:Allergic contact dermatitis is caused by an allergy to something, which touches the skin causing a delayed reaction, (delayed because the rash may not develop for hours or a day after contact). It is less common than irritant contact dermatitis. Allergy is a very individual mechanism within the body, whereas irritation would eventually occur to anyone, if the skin is exposed to strong enough chemicals. Development of this type of allergy may vary considerably. Often it takes months, or even years, of contact with a particular substance, then suddenly for reasons not always well understood, a person becomes allergic to it. Sometimes an allergy can occur within days of first contacting a substance. The process within the body of becoming allergic usually takes at least ten days, so the rash will not occur the first time someone is exposed to a substance. However, once a person is allergic to something, a rash will develop whenever they touch or come into contact with that particular substance again. If the skin is already damaged or irritated, such as with irritant contact dermatitis, there is more likelihood of developing an allergy. The rash of allergic contact dermatitis often appears similar to the rash of irritant contact dermatitis. It may be worse and come on more suddenly, with the development of severe itching and blisters, although these symptoms can also be seen in both irritant contact dermatitis and hand eczema. It may sometimes spread to other areas, either through skin contact with the offending allergen, such as from touching the face with contaminated hands, or through a different mechanism. This mechanism is called an "id" or hypersensitivity eruption. An id eruption is like a sympathy rash, because areas of the body not contacted by the allergen, develop the rash as well. Diagnosis of allergic contact dermatitis: Patch testing is the special technique used to diagnose allergic dermatitis.
Note: Patch testing is quite different from 'prick' testing, which is the test for allergies causing hayfever or asthma, and for food allergies. Examples of common allergens, which cause allergic contact dermatitis, are: Chemicals
Hairdressing allergens
PPD (hair dye, mentioned above) has recently been an important cause of allergy to so-called "henna tattoos" which in some cases, although they may be mostly henna (a plant extract), often have hair dye mixed in. This allergy can be extremely severe as the dye is applied in much stronger concentrations than when applied to the hair, and in some cases is actually scratched into the skin. Cases have been reported from people who have had the 'tattoo' applied when they have been on holiday in Bali and also other destinations. Further reactions usually occur after returning home and having their hair dyed, where they develop an extreme reaction. Epoxy resins are a potent cause of allergic contact dermatitis and often cause quite severe reactions. As well as the hands and arms, reactions can also appear in an airborne-contact distribution, which means on the face or neck especially on people who are leaning over the chemicals such as epoxy floor applicators. Chromate which is present in cement. Chromate may be rendered inactive with the addition of ferrous sulphate to cement, which has occurred in Denmark with resulting decrease of chromate allergy. Chromate allergy may persist for some time even after avoidance of the allergen. Chromate is also used in the tanning of leather. Substances applied to the skin
Treatment and ongoing prevention of allergic contact dermatitis:This is similar to the treatment and prevention of irritant contact dermatitis.Awareness People diagnosed with allergic contact dermatitis should be aware of possible sources of the allergen that caused the reaction, and avoid all contact with those sources. Unfortunately, no de-sensitisation is available for this type of allergy. Avoidance is the key. Substitution of skin allergens Changing the chemical, where there are known hazards, with a less harmful substance is an important principle of occupational hygiene. Protection of the skin Use of protective gloves, and to a lesser extent clothing, is important to protect the skin, depending on the type of exposure to the relevant allergen. However, generally, substitution of the allergen is preferred to the use of protective equipment. Change of job If a person cannot work without developing the rash, then either job modification or a change of duties is recommended.
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Contact UrticariaWhat is it:An urticarial reaction causes a 'weal and flare' type of reaction on the skin and usually occurs within minutes, or up to an hour, following contact with a substance. The reaction may be associated with itching and redness, and generally the skin settles back to normal a few hours after contact ceases. The reaction can be either immunological (known as immediate hypersensitivity or Type 1 immune response), or non-immunological. The type of contact urticaria discussed here is the immunological reaction, known as immediate hypersensitivity or Type 1 immune response. It is an allergic reaction to proteins contacting the skin. Diagnosis of contact urticaria: Prick testing is the technique used to test for this type of allergy. Small quantities of the substance are pricked into the surface of the skin, usually the inner forearm, and assessed after 15 and 30 minutes for the development of an itchy red lump. RAST blood testing (a special blood test) is also available for some allergens. Usually latex allergy is screened for by a RAST test, rather than, or before doing prick tests. Occupationally related causes of contact urticaria:
Latex gloves: Contact urticaria to latex gloves usually causes a localised reaction such as on the hands or where the gloved hands touch the body. However, in some cases it causes a systemic reaction or even anaphylaxis (shock). So this is a very serious condition. Risk factors for latex allergy include:
Non-latex or latex-free gloves are available and are made of either nitrile, neoprene or polyurethane. Vinyl gloves are useful in many circumstances, but are not viral protective, therefore do not offer appropriate protection against body fluid contact. Prevention of Latex Allergy:
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| Occupational Dermatology
Research and Education Centre, P O Box 132 Carlton
South Vic 3053 Australia
ph)+613 9639 9633 fx)+613 9639 9644 |
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