Occupational contact dermatitis is caused entirely by external factors
related to a person’s work environment. It is a delayed inflammatory
reaction that occurs to people when their skin comes in direct contact
with various sensitizing allergens and irritants present in their place
People with occupational dermatitis belong to a wide variety of trades
and professions and include beauticians, construction workers, cooks,
farmers, medical personnel, printing industry workers, and food handlers.
In most cases, occupational dermatitis affects the hands alone but may
spread to the forearms. The face may be affected if air-borne agents are
the cause. Triggers can include things like hair products, jewellery,
cosmetics, cloth dyes, rubber, leather and cement.
The development of this condition is often abetted by some pre-existing
skin conditions, such as, atopic diseases.
Types of occupational dermatitis
Occupational dermatitis covers a range of delayed skin reactions but
mainly include irritant, allergic, urticaria and photo contact dermatitis
Irritant contact dermatitis
This type of occupational dermatitis accounts for about 80% of contact
dermatitis cases. It occurs mostly on the hands, where the skin, due to
chronic exposure to some cleaning agent or sensitizing irritants, produces
a localized inflammation. There are two types of irritants, classified
as immediate and cumulative irritants. The immediate irritants are strong
acids or alkalis which produce reactions within minutes or hours. Cumulative
irritants, such as, petroleum products and weak acids or alkalis work
slowly so that the worker only becomes aware days, weeks or months after
It is common among people engaged in, what is called, the “wet
work” occupations, such as, cleaners, hairdressers, health care
personnel, cooks and food handlers. These irritants work by entering and
impairing the skin’s natural protective barriers, as a result the
skin progressively becomes dry, scaly and cracked leading to eczematous
dermatitis. Chemicals, such as, solvents, detergents, cutting oils and
urine ammonia in nappies are common triggers. The condition often occurs
where the skin is thinnest, so the common sites are finger webs and back
of the hands rather than the palms.
Allergic contact dermatitis
Allergic contact dermatitis is an immune system mediated condition that
develops in stages, after prolonged exposure to an allergen at the workplace.
The first stage is the sensitization stage when allergens enter the outer
layer of the skin. No skin reaction is visible at this stage. The rashes
take about 48 hours to appear and are sharply defined at the place of
exposure or contact. In some cases, rashes may take several weeks to appear.
The rashes appear when the sensitized worker is later re-exposed to the
allergens which react with the skin’s protein and weaken the immune
system of the skin. This results in itching, pain, redness, swelling and
blisters on the skin.
The inflammation in allergic contact dermatitis is normally confined
to the region of contact or exposure with the allergen but in severe cases
it may be spread wide on the body. The condition is usually at its worst
in 3 or 4 days after the first exposure. While treatment can improve the
condition in about a week, the allergic sensitization may remain with
the person for life. Without treatment over time and repeated exposure
the skin may thicken.
The common triggers for this allergy are common metals, especially nickel;
dyes, rubber products, plant allergens and cosmetics.
Contact urticaria is different from other forms of occupational contact
dermatitis in its clinical manifestations, its time sequence, the triggering
agents, and mechanism of action. The clinical reaction appears on the
site of direct contact, usually the fingers, but consists of small itching
wheals, emerging within 10-20 minutes after contact and quickly disappearing.
The triggering agents may be latex rubber in gloves, animal proteins or
other foodstuffs. The patients are often health care personnel, chefs
and workers in the meat and fish industry.
The responsible allergens are high-molecular weight, complete antigens
that are normally not absorbed by the skin. Therefore, a damaged or infected
skin barrier system is needed to facilitate their entry. Contact urticaria
patients usually have an atopic condition.
Photo contact dermatitis
Photo contact dermatitis is caused by the action of ultraviolet light
on a skin, which has certain sensitizing agents. The implication being
that mere presence of the sensitizer will not produce contact dermatitis.
People will not get this condition if they stay indoors. Exposure to ultraviolet
radiation is also necessary along with the sensitizing agent before photo
contact dermatitis develops. That is why photo contact dermatitis always
occurs on the light exposed parts of the body. Common sensitizers are
found in plants seen almost everywhere, such as, parsnip, fennel, carrot
and celery. Photocontact dermatitis is therefore seen sometimes among
the farming communities.
Avoiding further exposure is alone a major part of the treatment. Further
drug treatment approaches are no different from those used in contact