Asbestos – the effects on lungs

What is Asbestos?

The term asbestos covers a wide spectrum of naturally occurring minerals. The minerals coalesce into tiny fibres which can be divided into two main subtypes: Serpentine – flexible and curly shaped or Amphibole – which are needle shaped. The serpentine shaped fibres are always made up of white (chrysolite) asbestos, but the needle shaped asbestos fibres can consist of blue (Crocodilite) or brown asbestos (Amosite, Tremolite; Anthophyllite; Actinolite).

White asbestos accounts for most of the world’s asbestos production but blue asbestos has been particularly associated with cancers and mesothelioma and a voluntary ban on it’s manufacture was initiated in 1969, followed by a complete ban in 1986,.

Which occupations were particularly exposed to asbestos?

The properties of asbestos meant that it was used extensively in thermal, electrical and sound insulation. The production and consumption of asbestos peaked in the 1970s, although it is still processed in smaller quantities, even today in Europe and North America. As a result the occupations at risk of asbestos exposure include:

Electricians
Insulation workers/Laggers
Carpenters
Boilermakers
Ship- building
Power station workers
Plumbers and pipe-fitters
Railway workers
Construction and Demolition workers
Mechanics (used in brake-linings)

The families of those exposed to asbestos may also be exposed, as workers can carry fibres home on their overalls.

Asbestos-related Diseases

The following conditions may occur following inhalation of the tiny asbestos fibres:

Mesothelioma
Lung Cancer
Asbestosis
Diffuse Pleural Thickening
Benign Pleural Effusion
Benign Pleural Plaques
Rounded atelectasis or folded lung Mesothelioma

MESOTHELIOMA

This is a malignant tumour of the lung (or abdominal) lining. Because it takes a long time for mesothelioma to develop following asbestos exposure, many workers will still continue to contract the disease, from inhalation a long time ago. The incidence of mesothelioma has been increasing, expecting to reach a peak in the year 2017. The estimated number of deaths due to mesothelioma is expected to double, perhaps even reaching about 250,000 deaths worldwide over the next 35 years!

Continued exposure, or exposure to denser amounts of fibres increase the risk of developing this tumour, however it can occur even after very low exposure. Smoking is not a contributory factor to this type of cancer.

The tumour starts as a small area of thickening or ‘mass’ on the lining of the lung, and then spreads to encompass the lung and invade the ribs, or surround other vital organs inside the chest. Only extremely rarely can it spread in the blood to other parts of the body.

Symptoms usually include breathlessness (especially if fluid builds up around the lung). There may be severe pain, fever, weight loss and severe fatigue. When examining a patient, doctors look for reduced movement of the ribs when breathing, and signs of fluid on the lungs. A Chest x-ray often confirms fluid (see example 2) or thickening of the lung covering (example 3).

Diagnosis can be difficult, but doctors look for mesothelioma cells in the fluid or by taking a biopsy of the lining of the lung. Often they use scanning to make sure they get good samples but sometimes a major operation with general anaesthetic is needed to get the appropriate cells.

Unfortunately treatment can be difficult. Very rarely, mesothelioma can be removed by surgery if it is caught early enough, but often by the time patients develop symptoms, it means the tumour has spread outside of the lungs to cause fluid (breathlessness) or damage to surrounding nerves (pain). Ongoing research is looking at the roles of chemotherapy and radiotherapy, particularly in reducing pain and breathlessness. Sometimes nerve blocks (injections near the spine and ribs) can also help pain. More work needs to be done in research, as most patients with mesothelioma still do not live more than 2 years after diagnosis.

Lung Cancer

All types of asbestos can increase the risk lung cancer. The risk of cancer increases, the more and the longer people are exposed to asbestos. Patients who smoke and have had asbestos exposure are at the highest risk of lung cancer (at least 30 times the risk of other people!) – so all smokers are strongly encouraged to stop smoking, immediately. The management and prognosis of asbestos related lung cancer is similar to that of other lung cancers, but operations to cure the cancer are often less possible as scarred lungs cannot stand the big procedures involved.

Asbestosis

This is scarring and inflammation of the spongy lung tissue itself. It is usually diffuse (all over the lung) but is often most dense in the lower half of the lungs and affects both sides at once. It requires heavy exposure and may take up to 15 – 20 years following first exposure to develop. Symptoms are usually progressive breathlessness, dry cough and sometimes weight loss. One third of those with asbestosis may develop curved or swollen finger nails, referred to as “finger clubbing”. Diagnosis is made by taking a detailed occupational history and hearing crackles (like peeling apart Velcro) at the lung bases with a stethoscope.

A chest x-ray maybe normal but usually shows evidence of lung scarring, such as fine lines or multiple dots in the lungs. A more detailed CT scan of the lungs is often more helpful (see example 1). Sometimes asbestos particles can be seen under the microscope in a patients spit or fluid samples from the deeper parts of their lung, but this is rarely done by doctors.

There is no cure or definite way that doctors can slow down the lung fibrosis. Treatment is mainly supportive with advice to quit smoking, take regular (outdoor) exercise, eat a healthy diet and to attend for winter vaccinations. Sometimes home oxygen can help more advanced cases, if patients do not have enough oxygen in their blood.

Doctors should inform the coroner of the death of anyone with asbestosis, to ensure Government statistics are accurate.

Diffuse Pleural Thickening

This can often occur after single exposure and affects the lining of the lung, especially the lower half. It usually occurs on both sides of the chest and can extend to cover up to four ribs. It can cause symptoms of progressive breathlessness and reduced chest wall movement, as well as chest pain.

A CT scan is usually needed to accurately record the extent of the pleural thickening.

Again, unfortunately symptoms can progress or stay the same. The thickening does not get better and treatment consists of the same general lifestyle advice (as above), painkillers and oxygen – if needed.

Benign Pleural Effusions

This is where fluid builds up between the lining of the lung and the inner lining of the ribs. It may pass without any symptoms or present with acute breathlessness, fever and sharp chest pain. The fluid (effusion) can be on one or both lungs. They tend to resolve without treatment, however if a patient is particularly breathless, the fluid can be removed with a needle or chest drain. However, fluid can recur at a later date.

Benign Pleural Plaques

These are smooth elevations of the lining of the lung. They are strongly associated with asbestos exposure, and may occur even after low exposure. They usually take at least 10 years to form. Plaques do not cause any symptoms in themselves and can be picked up on routine chest x-ray. Although the plaques are not thought to be precursors for cancer, the incidence of malignancy is higher in these individuals, because of the background exposure to asbestos.

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Rounded atelectasis or folded lung

This was thought to be a rare condition but is increasingly recognized with CT scans. The exact cause is unknown and it has been recorded in other conditions besides asbestos, lung disease. It is believed to be a benign condition, where the lung folds up on itself. It looks like small rounded areas of dense lung which are often mistaken for lung cancers. Patients may present with progressive chest pain and breathlessness, or may be asymptomatic.

Treatment is painkillers or surgical removal.

Conclusion

Asbestos-related lung disease will be seen now and in the future on a more frequent basis due to the lag of time between exposure and disease presentation.

It has a huge implication on the health of those whom have one of the diseases and the family that look after them. This website is aimed to raise awareness and offer some information as well as to help those who are affected.

Authors:

Dr Robin Ghosal,

Registrar in Respiratory Medicine,

Prince Philip Hospital, Llanelli

Dr Keir Lewis

Consultant in Respiratory Medicine and Senior Lecturer,

Prince Philip Hospital, Llanelli

Images by:

Dr Grant Griffiths

Registrar in Radiology,

Prince Philip Hospital, Llanelli