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|. 2.0 Dermatitis Caused By Plants  |
In layman's terms any skin disorder is usually labelled as an eczema. For this study we will only be
using the term dermatitis. Eczema is an inflammation caused by internal disorders, and inherent genetic mutation. There are two types of dermatitis, irritant and sensitised. There is a clinical distinction between the two, and both have a greater effect if the body is under stress. Irritant types are more common, as they are able to affect anyone.
FIGURE 2.0.1 Highlighting The Differences Between Allergic & Sensitised Dermatitis.
2.1 Categorising Severity
There may be several levels of reactions which can be classed by severity, and can be diagnosed by
the level of exposure to a chemical. People vary in the way they react to a chemical, and depends
on their state of health, age and previous background.
2.1.1 Acute is characterise by redness, itching, erythremous rash and serous exudate, which may
saturate clothing.. Oedema is common. Secondary infection may occur in untreated cases.
2.1.2 Subacute includes all the above, but oedema and exudation will not be seen. It is painful, and itchy. This will with continuos rubbing produce crusting and excoriation. Bullae and vesicles commonly seen.
2.1.3 Chronic refers to long standing lesions which take 3 months to develop after initial exposure, due to constant rubbing and itching because of the pain. This will elicit a protective acanthuses, crusting , and thickening of the skin. This is termed as lichenification. Secondary infection is common.
2.1.4 Systemic Anaphylactic Shock  Does occur occasionally in people who have rolled
in a bed of nettles, celery, or have a condition which makes them extremely sensitive to certain chemicals
It is a severe reaction, which will induce all the above effects, With generalised laryngeal oedema, pruritus, hives, pallor, restlessness, asthma, apprehension, vomiting and coma. Death may occasionally occur if
severe cases are accompanied by an underlying disorder, or shock may trigger a heart condition. Many
other severe cases of poisoning and death are due to internal ingestion of plant products, which
is not covered here due to the wide range of effects. Rhus species touching the lips has been known
to cause vomiting, diarrhoea and rash.
2.2 Irritant Contact Dermatitis 
Is due to direct contact by a chemical or compound from a plant on the skin, causing damage to
its natural barrier, causing inflammation. The substances likely to cause it are phenols, halids, alkalis,
acids, ammonias. The onset is usually rapid, occurring within seconds. A usual reaction will be
stinging pain, redness, erythremous rash, flaking of the skin, bullae, lesions, vesicles, weeping oedema and itch. As skin heals fissuring crusting are seen. The skin is susceptible to secondary infection at
this stage. When caused by contact with plants, streaking across the skin is usually seen.
The HS at Work 1974 defines it as: "Caused by repeat exposure to an agent resulting in the removal
of natural oils, which crack and dry the skin. Accumulated effect in working women, as they
are exposed to numerous harmful substances."
There are several types of irritant contact caused by plants, which can be defined clinically as:
Neurodermatitis, Nummular dermatitis, Seborrhoeic dermatitis,
Statis Dermatitis, Herpetiformis dermatitis, Eryjrema multiforme
2.2.1 Hand Dermatitis Is a common and disabling irritant dermatitis, and may be seen in may
forms in 90% of people working in floristry. Most types look alike and the reaction is commonly
individual. Few go to the doctor, or report it. Doctors will also misdiagnose the cause. Common
irritants include acids and alkaloids, which will inflame the skin.
2.3 Acute Allergic/Sensitised Dermatitis
Is the result of acquired sensitivity to substances which come into contact with the skin. The sensitising agent will penetrate the epidermis via the sweat glands and hair follicles, and will combine with proteins
to form antigens. This sensitises the protective lymphocytes(Chap 1.4.2), giving a cell mediated
capacity to react explosively on subsequent contact with the chemical, producing severe inflammation
and rash. The condition is characterised by inflamed and itchy populous and vesicles. Dryness, scaling, fissuring are seen. It may be complicated by renewed exposure to irritant products, causing chronic exacerbation, and spreading lesions. At the time of contact the whole skin becomes sensitised, and so
further eruptions of the skin may not confined to the site of contact only. The latent interval can be 5 days
or years. The capacity to sensitise varies, and will usually occur before / at puberty, or in emotional or physical stress. If a child is not exposed to a substance before puberty he will rarely develop sensitised dermatitis. It is a common reaction and affects 30% of the population at one time. People in the industry,
who have been in contact with a plant for 30 years will suddenly erupt.
Allergic contact dermatitis is defined by the HS Act 1974 as "A reaction with a trigger substance, this
is less common than irritant but more severe. A reaction will occur every time that substance is encountered."
There are two other related types of sensitised dermatitis:
2.3.1 Phytophotic dermatitis [ 4 ] [ 5 ] Furocoumarins present in plants produce dermatitis
from contact with the skin, and subsequent exposure to ultra violet light after 48 hours. This causes
severe eruptions and vesicles. Stripped blisters may appear 12 hours after contact, it is common in
children, troops and farmers. Meadow grass dermatitis is a phototoxic eruption provoked by contact
with wild parsnip and other vegetation and exposure to sunlight. It is severe in contact with water.
It is an example of a complex cross reaction.
The plants containing furocoumarins include: Umbelliferae: Parsnip, Fennel, Dill, Parsley, Carrot, Celery, Angelica, Rutaceae: Common rue Moraceae: Fig Ranunculaceae: Buttercup
2.3.2 Pollen dermatitis [ 4 ] [ 5 ] Pollens containing a water soluble antigen are responsible for hayfever, characterised by tears, sneezing, asthma, coughing, redness from inhalation of the antigen. Allergic pollens may also land on neck, face and get into clothing causing serious sheet like eruptions all over the body and occurs particularly with ragweed, which is a common cause of dermatitis. The seasonal appearance is also accompanied by lichenification of the skin, and infections. The sites of contact are typically the face, neck, arms and legs, vesiculation may also be found here. It may resemble photosensitivity, but is different
in that the eruption is seen in covered parts of the skin. The shell of the pollen grain contains a oleoresin
fraction, which is an allergen. Reactions are common in gardeners, farmers and field workers
Dermatitis In the Horticulture Industry By James M. Burton In Association With Pencoed College Copyright 1997.
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