What is asbestos and where does it come from?

ASBESTOS is a naturally-occurring mineral fibre that is mined principally in Canada (Quebec), Russia and Zimbabwe.

It has been known about since Roman times and has been used for its fire resistant properties and for strengthening cement without making it brittle.

Over the last century, asbestos has been built into many different products including pipe lagging, ceiling tiles and water pipes. Workers have come into contact with asbestos in several stages:

· Mining (although not in Britain), transportation (including workers on merchant vessels bringing asbestos from the mining countries to Britain), dock workers;

· Manufacturing asbestos containing products and installing them in buildings and ships (especially lagging hot water systems);

· Construction work, including the use of building materials, but especially now work such as repair, maintenance and renovation;

· Working in areas where asbestos has been released into the working environment as it crumbles, such as teachers, doctors, clerical workers and so on.

Some people have been exposed to asbestos through what are known as para-occupational exposures, such as wives and daughters who cleaned the overalls of the men working with asbestos, or children playing in sites contaminated by asbestos either around factories, or where it has been dumped illegally.

When breathed in, asbestos fibres collect in the lungs and they take a long time to be absorbed.

Because of their long life, and because they are often very fine and able to penetrate deep into the lung, they are a potent carcinogen, and cause cancers such as lung cancer (and other cancers around the body), diseases like asbestosis, and especially mesothelioma, a cancer of the lining of the lung which can take over twenty to forty years to develop, and is usually fatal within eighteen months of diagnosis.

Mesotelioma is caused almost entirely by asbestos, so it is a "signature" disease, and its prevalence is the basis of most estimates of asbestos-related disease.

It is a very painful way to die, and is all but incurable, although there are some limited signs of hope.

Asbestos can also cause pleural thickening, which is a disabling disease of the lining of the lung, and pleural plaques, which show up on X-rays and indicate asbestos exposure, but which do not always develop into more serious conditions.

Asbestos comes in several forms, commonly known as blue, brown and white asbestos. Blue and brown asbestos are more potent than white, but it is clear that all of them cause cancer, and all of them have now been banned in the UK.

"Bristol Evening Post" 24th January 2002