The threat of asbestos

The threat of asbestos

For more than half a century, the construction fibre asbestos has been used in buildings for the insulation of pipes and boilers, as fire protection in walls, and even roofing and guttering. It generally does not pose a risk to health as long as it remains undisturbed and in good condition.

However, when it is damaged, asbestos fibres are released into the air. If inhaled, these can have very serious effects on health.

This is one of the problems which survivors of the attack on New York's World Trade Centre, as well as hundreds of workers involved in the rescue operation, may eventually face. BBC World Service Science reports.

Use of asbestos

The World Trade Centre towers were opened to the public in 1973. At the heart of the structure of each tower was a vertical steel and concrete core, housing lift shafts and stairwells. All the steel was covered in concrete as were the floors.

Because of its high melting point and because it's a fire retardant, asbestos was used to fireproof beams.

In the 1960s, when it was discovered that asbestos was a toxic substance and a known carcinogen, many countries banned the material.

By the time the ban was enforced and strict guidelines were implemented, builders on the World Trade Centre had already completed the first 40 floors of the north tower and had, allegedly, used asbestos.

Subsequent construction was completed with safer materials.

Level of contaminants

When fires engulfed the twin towers, health officials feared asbestos was released into the air.

However, officials in New York recently said dust samples tested at the site of the devastated World Trade Centre do not show dangerous levels of the contaminant.

According to the US newspaper New York Times, the US Environmental Protection Agency recently analysed 97 air samples from 11 sites in Lower Manhattan and four sites in New Jersey. It stated:

'Seven samples at or near the World Trade Centre attack site had marginally higher levels of asbestos, which exceeded the E.P.A.'s level of concern for long-term exposure. Rescue workers in this restricted area have been provided with respirators.'

As the rescue and clean-up operation continues, frequent air samples will have be taken to ensure that workers involved in the clearing of debris as well as investigators are not at risk of acquiring an asbestos-related disease.

Diseases

Medical experts have warned that exposure to the fibre when broken down into dust could cause a host of terminal diseases.

Asbestosis, a lung disease characterised by shortness of breath, is a major concern. Others are mesothelioma, a rare cancer of the lining of the abdominal cavity and surrounding internal organs, and pleural disease, which can result in calcification of the lungs.

Other cancers related to asbestos include lung cancer (worsened by cigarette smoking) and cancers of the oesophagus, stomach, colon and rectum.

Increase in diseases

While environmental experts in New York assure survivors and health workers of the low levels of contaminants in the area devastated by the terror attacks, scientists in Europe are now warning of a significant increase in asbestos-related illnesses in the coming years.

Experts attending the annual meeting of the European Respiratory Society in Berlin this week say that asbestos-related cancers, which are often fatal, will increase globally over the next twenty years.

In many cases, asbestos-related symptoms only appear decades – in some cases as many as four - after the original exposure.

One of the aims of the 11th symposium organised by the European Respiratory Society is to provide the clinician with the latest review of the imaging methods used to detect asbestos-related lesions.

Over 3,000 people a year die of asbestos-related diseases in the UK and numbers are predicted to rise to 10,000 a year by 2020.

High-risk group

Builders, electricians, plumbers and shipyard workers who drill into the insulation board and use it for construction are in the high-risk group. However teachers, children and nurses are also believed to have been put in danger since asbestos was used in the construction of schools and hospitals.

Families of those who work with asbestos can also be infected if asbestos particles are brought into the home on clothes.

Asbestos exposure was at its peak in the construction industry in Western Europe, North America, Japan and Australia until the 1970s; and although its use is nowadays carefully monitored, more than two millions tons was produced last year - and most of that is now used in poorer countries.