OCCUPATIONAL or industrial dermatitis does not differ from exogenous dermatitis previously described except for the circumstances of its onset. In the National Insurance Act, Prescribed Disease 42 is defined as non-infective dermatitis caused wholly or partly by contact with dust, liquid or vapour or any other skin irritant encountered at work.
(i) Traumatic dermatitis. Some 70 per cent of industrial dermatitis is caused by direct damage to the epidermis by friction from abrasive dust such as coal, stone or brick, or glass wool or the effect of primary irritants. Primary irritants include acids, alkalis and chemicals which when in contact with the skin for a sufficient time in adequate concentration produce cell damage. Included in this group are the simple alkaline degreasing agents such as soap and water or brine and the soluble oils or coolants used widely in the engineering industry. The more searching solvents like paraffin, petroleum and carbon tetrachloride, white spirit, paint thinners and turpentine are even more potent causes of skin damage.
(ii) Sensitisation or contact dermatitis. Many of the substances handled in industry like those in the home are sensitisers, but only a small proportion of workers at risk develop dermatitis and sensitisation is responsible for only 14 per cent of industrial dermatitis. Common examples are the epoxy resins used to join materials in numerous light industries, nickel and chrome solutions, dyes, photographic chemicals and sawdust from hardwoods such as teak, iroko or rosewood. Some primary irritants, such as the soluble oils, may at times act as sensitisers and they often contain antiseptics which are more liable to cause sensitisation than the oil itself. Chrome is a constituent of cement but the amount that cement contains varies greatly. Fortunately in Britain the chrome content is low and chrome dermatitis is less of a problem amongst building workers than it is in Europe.
(iii) The tired skin. After many years of wear and tear of the skin by very mild irritant dusts or liquids, dermatitis may develop. This is seen commonly in the elderly coal miner or building trade worker.
(iv) Constitutional eczema aggravated by exogenous irritants. An individual who is eczema prone is more likely to develop an exacerbation of eczema if exposed to working conditions which are unsuitable. It may be extremely difficult to decide what part has been played by exogenous irritants and such cases are often the subject of litigation. It can be argued that anyone who develops a dermatitis in conditions which do not harm the majority of his workmates, has a constitutional weakness of the skin and in support of this is the finding that the age distribution of coal miners with exogenous dermatitis was similar to that of coal miners considered to have endogenous eczema. Only after observation over a period of years may it be possible in an individual case to assess correctly the relative importance of exogenous irritants and constitutional weakness.
Diagnosis of industrial dermatitis.
It must be established that the skin lesion was not present before the worker started the occupation. The exact nature of the work must be known and this may entail a visit to the factory. Any recent change in working methods and materials should be sought. A recent injury to the skin may predispose the worker to an attack of dermatitis and in many cases the dermatitis may be due to antiseptics applied to a wound. A history of improvement at weekends and gradual recurrence during the week is suggestive and sensitisation sometimes starts after a holiday because some degree of immunity is lost.
The skin eruption usually begins in those areas most exposed to possible irritants. The hands and forearms are therefore the common sites and in right handed workers the right hand is more severely in-volved. The sides and backs of the fingers, the webs between and the front of the wrists are affected more than the palms whose thick horny layer acts as a protection. Primary irritant dermatitis due to solvents often starts beneath wedding or signet rings which prevent the finger being adequately washed and dried. Where a volatile substance is the cause the initial site may be the eyelids, face and neck. Dusts cling to moist skin and the axillae, groins and scrotum may be the initial sites affectcd. It should not be forgotten than cleansing agents and even protective clothing, gloves and barrier creams may cause dermatitis. Often the habit of rinsing the hands in a solvent to remove grease causes more damage than the long contact with oils throughout the working day and dermatitis caused by rubber gloves may complicate a simple traumatic dermatitis.
It is to be expected that industrial dermatitis should improve if work is stopped but in very chronic cases where the eruption has persisted for some years a state of eczema develops in which new lesions erupt without further contact with irritants. Here again the distinction between exogenous dermatitis and endogenous factors may be well nigh impossible. Once the skin defences have been broken down, nonspecific irritants such as heat, friction and washing can maintain the skin inflammation.
Special types of industrial skin disease
Dermatitis may follow injury and this should be distinguished from the usual prescribed disease. The dermatitis may be an infective eczematoid reaction after a cut or burn, or more frequently the result of the application of a sensitising local antiseptic to a wound. The patient can be reassured that it will be safe to return to his usual occupation since it was the wound and not the job which was responsible for the dermatitis.
(i) Industrial acne. A follicular pustular reaction on the face, trunk and limbs is produced by exposure to vapours of chlorinated naphthalenes used in insulating cable. More recently chloracne has been reported in workers who process the chlorinated phenols in the production of herbicides. So potent and active are some of these chemicals that even wives and children of workers who handle them, may be affected by acne. Similar lesions can be caused by coal tar and pitch but the most frequent cause is contact with insoluble cutting oils of high boiling point. These produce thickening of the keratin at the opening of the hair follicles which results in blackhead and pustule formation most commonly on the forearms and thighs. There is considerable individual variation in susceptibility and oil acne is more likely to develop in the young inexpert worker whose boiler suit becomes soaked in oil.
(ii) Chrome ulcers. Ulceration of the skin of the fingers and the nasal septum occurs in those exposed to chromic acid and chromates. The ulcer forms around trivial abrasions.
(iii) Occupational cancer. The substances which produce keratin change in the epidermis can over a period of years act as carcinogens. At first simple keratoses or warts which are non-malignant form, later keratoacanthomata, and eventually a true epithliomatous change occurs, possibly years after exposure to the carcinogen. Tar, pitch, bitumen and the mineral oils are the main offenders and lesions appear usually on the exposed skin but an additional classical site is the scrotum. Contact with pitch occurs in some unlikely trades, for instance optical lens polishing and an industrial origin should be sought for all warty lesions on the skin.
(iv) Skin damage from radiation. An increasing hazard is exposure to radio-active materials and x-rays which can produce an acute burn followed by a necrosis and ulceration or a chronic dermatitis with atrophy telangiectasis and cracking. Malignant change may complicate the chronic radiation damage.
It has been accepted in the coal mining industry that fungus infection of the toes is an occupational hazard and this is spread by the pithead baths. It affects up to 50 per cent of coal miners in some pits. The Ministry of Health and Social Security recognise this disease when it affects colliers and it is classed as an industrial injury.
The prevention of dermatitis in industry depends on several factors, selection of personnel, protection, cleanliness and education of the workmen. Although it is recognised that dark skinned workers are less susceptible to sensitisers and degreasing agents than fair skinned but more prone to folliculitis, it is seldom practicable to select employees on this basis. An attempt should be made to exclude from contact with degreasing agents those with dry ichthyotic skins and exclude from hot dusty surroundings the worker who has a previous history of atopic or seborrhoeic eczema. Regular examination and inspection of personnel should detect the early signs of keratoses and carcinoma.
As far as possible, workers should not be required to handle either primary irritants or sensitisers and to bring this about it may be necessary to redesign machinery. A policy of allergen replacement should be employed. Substances which are known causes of dermatitis should be eliminated, for example the inclusion of antiseptics in coolants. There is little need for these to prevent infection but they increase the risk of dermatitis. It may be possible to substitute vegetable for mineral oil and molybdate can replace chromate in paints for example.
Where some contact cannot be avoided, protective clothing, aprons, boots and gloves should be worn. Rubber or polythene gloves may cause maceration of the skin if worn for long periods. This can be prevented by wearing absorbent inner gloves. Boiler suits which are contaminated with oil or dust should be cleaned regularly. Numerous creams designed to be applied before work and to form a protective coating have been devised and yet there is no effective barrier cream, and a belief in the effectiveness may lead to the neglect of other more important steps in the prevention of dermatitis. The main virtue of barrier creams is in facilitating the removal of dirt and in reducing the trauma to the skin from scrubbing brushes, abrasives and soaps. Of more value in the reduction of dermatitis is the introduction of effective and safe cleansing agents such as the sulphonated oils and better facilities for washing at work.
Adequate discussion of the causes and prevention of dermatitis are helpful since neither worker nor manager will co-operate in preventive measures unless the need is understood. There is still a belief that dermatitis is contagious and that it carries a social stigma and this idea should be combated vigorously on the shop floor and in boardroom.
Treatment of industrial dermatitis.
In general the patient should cease contact with the cause of dermatitis though in a few cases such as in the explosives industry desensitisation or hardening occurs if the worker continues in the same job with less exposure. This is a rare phenomenon. The usual course of events is for the dermatitis to become worse if further contact is not prevented. This does not imply that the worker should cease work but he should be moved to some other job. The use of occlusive dressings should enable suitable dry hand work to be continued. It is much more difficult to resettle a man once he has been out of work, and the anxiety about his future aggravates the skin condition.
Change of occupation must be permanent for patients with sensitisation dermatitis as relapse speedily follows even slight contact with the offending agent. In traumatic dermatitis, return to the original job may be possible if provision is made for increased protection against the irritant. It has been found however that the relapse rate in traumatic dermatitis is far higher than in sensitisation dermatitis where the worker has been moved from the sensitiser. It has been our experience that workers of good morale settle themselves without assistance. Those who need aid are the elderly with the tired skin syndrome who have difficulty in finding a job. The individual with an inadequate personality cannot deal with the situation when he develops dermatitis and the patient who has had a long period off work becomes discouraged. They both need rehabilitation. The disabled persons’ register is of no value to patients with dermatitis because employers will not accept a known sufferer from dermatitis.