Asbestos related disorders
Exposure to asbestos and its fibres can cause lung diseases, including asbestosis, mesothelioma, diffuse pleural thickening and lung cancer.
Asbestos is not routinely used in many industries, such as building, these days. However, workers need special protection when working on, or demolishing, older buildings containing asbestos.
Asbestosis-scarring of the interior of the lung.
Asbestosis is a process of lung tissue scarring that is caused by asbestos fibres. Because many other diseases also lead to lung scarring, these other causes must be excluded first when a patient is found to have lung scarring. Patients with particular x-ray findings or biopsy results must also have a remote history of asbestos exposure and a characteristically delayed development of the condition in considering asbestosis as a diagnosis. Smoking appears to increase the frequency and/or the rate of progression of asbestosis, possibly by preventing the efficient elimination of inhaled fibres from the airways.
What are symptoms and signs of asbestosis?
The clinical symptoms usually include slowly progressing shortness of breath and a cough, often 20 to 40 years after exposure to asbestos. Breathlessness advances throughout the disease, even without further asbestos inhalation. In the absence of cigarette smoking, sputum (mucus coughed up from the lungs) production and wheezing are uncommon. The exception is workers who have been exposed to very high concentrations of asbestos fibres. Those workers may also develop symptoms as soon as 10 years after exposure. Other indications of asbestosis include abnormal lung sounds on examination, changes in the ends of the fingers and toes ("clubbing"), a blue tinge to the fingers or lips ("cyanosis"), and failure of the right side of the heart ("cor pulmonale").
What tests and studies are used to evaluate asbestosis?
Breathing abnormalities can be identified with lung function tests or exercise tests that are performed at specialised laboratories. Asbestosis can produce both obstruction of airflow and restriction of lung inflation. In addition, the disease can affect the ability to transfer oxygen into the blood. With advanced disease, patients may have markedly reduced blood oxygen at rest and may need supplementary oxygen.
X-ray abnormalities include thickening of the lining of the lungs and tiny lines marking the lower portions of the lungs. However, up to 20% of patients have completely normal-appearing chest x-rays. These patients may demonstrate more subtle changes on computerised x-ray studies (computerised tomography, or CT scans). Up to 30% of patients with a normal chest x-ray who have been exposed to asbestos will have an abnormal high resolution (high definition) CT. The CT scan may be very useful in separating true asbestosis from other conditions that may have similar findings. However, even a CT scan may not identify disease of the lining of the lung (pleural disease) in patients with asbestosis.
Laboratory studies may be abnormal (certain antibodies and markers of inflammation), but they do not specifically suggest asbestosis.
A biopsy and microscopic examination of the lung is rarely used to diagnose asbestosis. When it is done, certain coated fibres (asbestos bodies) can be seen in association with a pattern of scarring. The amount of both coated and uncoated (transparent) asbestos has been linked to the severity of asbestosis. Because other particles may resemble asbestos, a conclusive identification may require scanning electron microscopy. Currently, detection of asbestos fibres in the lung tissue and fluids (sputum, secretions) can be used to make the diagnosis, along with a history of asbestos exposure and characteristic x-ray or CT results. It should also be noted that the currently available commercial form of asbestos, chrysotile, does not form asbestos bodies as easily as previously used fibres.