Is one of the biggest and longest running asbestos myths to be finally debunked once and for all? Results from research carried out in a German university, which were published earlier this year in a European medical journal, show that white chrysotile – the so-called “low risk” asbestos – remains in the lung tissue for the same period of time as other fibre types.

Whenever white asbestos is suddenly discovered in a premises, the standard statement of spokesmen for local authorities and other organisations is that the type found is “low risk” and poses no danger to employees, contractors or other members of the public. The prevailing level of asbestos awareness to the potential health risks linked to white chrysotile can be traced back to conclusions reached following the results of research carried out in the mid 1980s.

The first UK ban was introduced in July 1985, which ended the use of brown and blue asbestos fibres as an insulation material. By the 1980s, there were around 1,000 cases of mesothelioma and more than 250 cases of asbestosis disease reported each year, according to the The Great Britain Asbestos Survey 1971-2005, published by the Health and Safety Executive (HSE). However, white asbestos was allowed to continue being used in the manufacture of building materials as a cement binding agent, such as pipe lagging, wallboards and roofing sheets.

Decision not to ban white asbestos was based on the limitations of the studies

The reasoning behind the decision not to ban white asbestos was based on the limitations of the studies themselves and the presupposed ability of the human immune system to expel the different fibre types over a period of time. Early research was based on animal experiments or from analysis of data collected from workplaces and autopsy results to produce hypothetical models.

In addition, it was found that white asbestos fibres are curly or “serpentine”, and are longer, thinner and more flexible than the insoluble rigid, needle fibres of brown ‘amphibole’ amosite and blue ‘crocidolite’ fibre types. It was concluded at the time that chrysotile particles were less likely to be permanently embedded in the lung linings and more able to be “broken down”. Consequently, it was thought that a higher number were likely to expelled over a shorter period of time.

Because there is usually a long delay of up to 50 years or more before the first asbestosis symptoms appear, it was also believed that the risk of cancer cells developing would decrease over time. As a result, a myth arose that chrysotile fibres “ by themselves” were not harmful. Yet, exposure to and breathing in of chrysotile asbestos fibre dust particles alone, has consistently been found to eventually lead to mesothelioma.

Now, new German studies look set to overturn the early research and the long-held belief that white asbestos is ‘low risk’. Incredibly, it was the first time that a study has been carried out to test the presence of asbestos in humans “over time”.

Samples contained high concentrations of white asbestos

Using the latest electron microscopes, it was revealed that just over two thirds of biopsy tissue samples contained high concentrations of white asbestos – at least 500 fibres of asbestos per gram of lung tissue – while the rest contained mainly brown or blue fibres. The period of time between biopsies varied from four to 21 years, carried out either during diagnosis or surgery, or part of an autopsy.

The results of the researcher data clearly shows white asbestos can be just as toxic as other forms of asbestos and should be treated with the same level of concern. There could also be an impact on recognising the validity of a mesothelioma claim, which can depend on the number of asbestos fibres present in the lungs. The method by which this is assessed has been in place for 40 years.

The Helsinki Criteria was agreed by an international panel of medical experts in 1977 but have since been seen to take no account of the different relative risks by industry and type of fibre exposure. The original estimated cumulative exposure to all asbestos fibres was set at 25 fibre/ml years or more, later revised for just counting brown and blue fibres. The threshold was increased to 40 fibre/ml years for equal exposure to white as well as brown and blue fibres. Could it be that that the refinement was likely to have been influenced by 1980s research and subsequent decision not to ban white asbestos, which was finally enacted in November 1999?

The results of the new German research may help to correct the previous assumptions over the likely long term health risks of white asbestos. A Parliamentary Group has recently called for a “timetable” which will see the removal of asbestos from every single workplace in Britain by 2035. Until the presence of white asbestos in millions of buildings around the UK – including 80 per cent of schools – is no longer accepted as low risk then the health dangers look set to continue.