It is important to state the obvious at the beginning. Occupational lung diseases are preventable. This is achieved by either preventing agents being released into the workers’ environment or preventing agents released into the workers’ environment gaining access to the workers’ lungs. The former method is the area that effort should be concentrated on.
Mechanism of disease creation
There are two basic mechanisms by which inhaled agents can cause occupational lung disease. In some people these may occur in combination.
The first mechanism is a direct effect of the agent on the organ that is exposed to the agents. Lung disease generally results in those exposed to the agent if they breathe in a sufficient quantity of the agent. This might mean a heavy exposure over a short period or a low exposure over a long period. The second mechanism is a reaction of the person who is exposed to the agent that causes the disease. This reaction could be referred to as an allergic or hypersensitivity reaction on the part of the worker. It might be contributed too by the genetic makeup of the worker and this means that all workers exposed do not develop the problem. The worker may have been in the industry sometime before this reaction manifests itself. Once it does, the worker can react to any small exposures after that and this reaction may continue once the worker is removed from that environment.
There may be a combination of both mechanisms in some people when it could be a factor of both dose and an individual reaction to the offending substance.
The only way these conditions will be diagnosed is for the person’s occupation to be considered when somebody presents with a problem, in this context a respiratory problem.
It is important to consider the person’s occupation from the time they left school until present.
Now people are presenting with conditions which were traditionally thought of as being due to occupational exposure but their exposure was to the agent outside the occupational setting. Examples of this include the worker’s partner, usually female, being exposed to the worker’s clothes when they return from work; other family members for example children being exposed in a similar fashion; people living in the environment of the factory; actual material being bought home from the workplace; being in an area where material was disposed of inadequately or using or removing a certain material in the domestic setting.
If one does not take all the above into account then the diagnosis may not be made or delayed.
Anatomical areas of the lungs involved
The disease process may involve the airways or conducting system of the lungs; the gas exchange part of the lungs or lung tissue (alveoli); the lining of the lungs or pleura or a combination of the above.
Symptoms & signs
The symptoms will be those associated with the particular condition and will be no different from those due to other causes of that condition. The symptoms will be those associated with the local problem and those due to general effects the condition will have on the body as a whole. The local symptoms will be breathlessness on exertion but may occur later at rest; cough which may be dry but can be productive of sputum. The sputum may be clear or discoloured. If it is discoloured it could be yellow or green due to inflammatory material or it can be blood stained. There may be abnormal sounds on breathing such as wheezing which indicates airway narrowing. There may be pain which might be constant and may radiate into the arms or it may be made worse on breathing (pleuritic). It is important to note what time of the day and what day of the week the symptoms come on. It is just as important to note if there are periods when they resolve.
The systemic symptoms include fever, sweating, tiredness, lethargy, anorexia, nausea and weight loss.
The physical signs are similar to the symptoms. They might be local signs confined to the lungs and signs consistent with the disease process in general.
The former might include respiratory distress, change in colour due to lack of oxygen (cyanosis), change in appearance of fingers (clubbing); reduction in movement of the chestwall and a change in breath sounds.
The breath sounds might be magnified, modified by airway narrowing for example wheezing; abnormal tissue in the gas exchange part of the lung (crepitations) or the breath sounds might be reduced by the presence of fluid or tumor in the pleural space. There might be abnormal lumps or bumps in the chestwall or related areas due to tumour spread.
The general signs might be fast heart rate, fever, and evidence of weight loss.
These are tailored to the condition but could include some or all of the following.
Blood tests will not be specific for a particular problem but will usually be abnormal in someone very ill. Arterial blood examination is a way of showing if the oxygen and carbon-dioxide content of the blood are normal or abnormal.
A chest x-ray and chest CT scan will indicate if the process is visible radiologically. If it is the area of the lung involved, the extent and spread of the process can be determined. Newer diagnostic methods such as PET scanning are playing a role in distinguishing benign from malignant processes.
Lung function tests
These are very important as these can indicate how the process is affecting the workings of the various parts of the lung and is an objective measure of how disabled the person might be as a result of the process. They are important in monitoring response to treatment.
If the above indicates there is an abnormal process going on in the lungs, the only way of determining what the process is, is to examine cells or tissue from the involved area. There are some conditions which do not require this and the diagnosis is obvious without the need for this.
If not, cells or tissue may be able to be obtained by a needle aspiration of the involved area. It is critical this be performed by people experienced in the field (and only after the patient is appraised of why the test is being done, the benefits of the tests and the complications that may occur) and the material obtained is sent to a pathologist expert in the field.
In some situations it may be that the material has to be obtained by an invasive surgical procedure that may be limited in extent (a VATS procedure – video assisted thoracoscopic surgery) or may require a thoracotomy. The tissue may be obtained as part of a therapeutic or palliative procedure.
It is critical that the surgeon performing the procedure is experienced in dealing with occupational lung problems and, again, as is the pathologist. The more tissue that can be obtained the better.
Sometimes it may be important to instruct the surgeon to send material for microbiological culture. Sufficient tissue will allow for later tissue analysis for various markers as well as fibre counting.