The Gazette 1990

GAZETTE

JANUARY/FEBRUARY 1990

Occupational Diseases — The Problem of Time

Thus, lung cancer is a risk faced by asbestos workers, but how do you tell what proportion of the lung cancer in asbestos workers is due to their asbestos exposure or to their smoking, or just plain chance? Asbestos - A useful example In a brief introduction to some of the problems of the relationship in time between occupational disease and its cause, I am going to take the example of asbestos and asbestos related diseases. I believe it will serve as a useful example to indi- cate problems of multiple causes, non-specific as well as specific occupational disease, the problem of attributability, and, in the case of cancer, the problem of the long latent period. Asbestos related Diseases The problem of what diseases are related to asbestos is in fact com- pounded by the fact that there are certain health effects (such as "pleural plaque") which are not considered as diseases at all by most clinicians. In other words they

Occupational disease may be acute, chronic, allergic, localised, or systemic. It may be due to a multiplicity of causes or one obvious and specific cause. There is also the problem of sorting out those occupational diseases which are specific to the occupation from those which can occur spontaneously in the general population.

skin or by being inhaled. Systemic disease such as heavy metal poisoning (lead), or organic chemical poisoning (benzene) will have effects on many different areas of the body (the brain, blood, and various organs). Dr. Dan Murphy M.B., F.F.O.M., D.I.H.*, Director Occupational Medical Services, National Authority for Occupational Safety & Health Something we may well have to deal with in the future are the effects of stress on general health. At the moment, despite many well founded suspicions about the effects of stress there is no meas- urable way in which a particular state of ill-health can be attributed to a particular stressful work situation. There are two final problems when dealing with occupational diseases which I will try to cover briefly. The first of these is that in fact many occupational diseases have more than one cause whether in the occupation itself or in the occupation and the individual's private life (asbestos and cigarette smoking). Next there is the problem of specific occupational disease versus non-specific. Asbestosis is a specific occupational disease. Lung cancer, also known as carcinoma of the bronchus, is sadly a common cancer. One study showed that in a group of asbestos workers, with asbestosis, followed up to the year 1963, just over 50% of them had died from lung cancer.

Examples of what I mean by acute occupational disease would include gassing accidents, which may either kill the unfortunate worker or result in long-term disa- bility, and acute irritant dermatitis (which can also be referred to as a "chemical burn"). By chronic I mean those diseases which are neither curable nor self limiting such as asbestosis. By allergic occupational disease I am referring to dermatitis of the allergic variety and one of our biggest problems at the moment, occupational asthma. Allergic alveolitis is best known in this country as farmers lung, but the condition can also occur in malt workers, mushroom growers and a host of other, agriculturally related, occupations where exposure to various spores occurs. By isolated conditions I refer of course to dermatitis and the various diseases of the lung. Skin diseases, using data from the Department of Social Welfare Occupational Injuries Benefit Scheme, make up roughly two thirds of occupational diseases claimed for under this scheme. Lung diseases would be a consider- ably smaller proportion but skin "At the moment . . . there is no meesurable way in which a particular state of ill-health can be attributed to a particular stressful work situation" disease and lung disease are a sizeable proportion of occupational disease overall. The reason is obvious: this is where the hazard strikes first, either directly on the

Dr. Dan Murphy.

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