Discovery of white chrysotile asbestos in any property should be followed by a rigorous and intensive sample analysis to exactly determine the condition of the material and if it should be left in place under controlled management or completely removed. Despite considerable progress in overall asbestos awareness and knowledge there can still be widespread confusion over the so-called “low-risk” status of chrysotile and the potential health risks.

The issue of risk level is mostly seen to be acted upon when white asbestos dust is found in a school premises. Invariably, there is an immediate evacuation and sealing of the entire building until a full analysis has been conducted and a decision taken over whether the asbestos-containing materials are to be left in place and “managed” or removed. However, this may not always be the case when commercial premises or public housing are involved. The Health & Safety Executive (HSE) regularly prosecute firms who either neglect to conduct asbestos surveys before starting work or fail to observe the strict procedures for removal, if asbestos is found.

Doubt created over risk extent

At court hearings, however, it is still possible for a defence to be made, which creates doubt over the extent of the risk of mesothelioma or asbestos-related diseases caused by an exposure to white chrysotile in the workplace. In addition, there can also be the added complexity of determining employer liability for non-occupational, ‘environmental’ exposure. There is also growing evidence of spontaneous or “idiopathic” mesothelioma, which can also occur in the absence of any known exposure to asbestos.

As recently as May 2011, HM Government Office for Science said that it was “not possible to determine a threshold level below which exposure to ‘pure’ chrysotile could be deemed ‘safe’ for human health. On the evidence available there is no justification for an imminent change to the international scientific consensus on the classification of chrysotile as a Class 1 carcinogen.”

In the same year, the UK was repeatedly called upon to comply with guidance set out by the European Asbestos Directive, which addresses the issue of “sporadic and low intensity exposure to asbestos” rather than simply measuring the extent of exposure and risk.

Myth goes back thirty years

The persistent myth that continues to describe chrysotile asbestos as being “low risk” to human health goes back some thirty years. In 1985, the most toxic brown and blue asbestos mineral types were banned from their widespread industrial use in the production of insulation materials. It’s also likely that at the time, white chrysotile was only viewed as relatively low risk because it was compared to the extremely high risk brown and blue asbestos. As a result, white asbestos was allowed to continue in the manufacture of building materials, including wallboards, roofing sheets and tiles, cement and surface coatings.

Much of the argument against a ban on white chrysotile was based on the critical difference between the different types of asbestos fibres and the ability of the body to break down and rid the body of the different types over a period of time. Blue and brown asbestos fibres are classified as ‘amphibole’ – straight, needle-like structures – which are impaled within the lung linings and are almost impossible for the body to clear. White asbestos fibres are the only category of ‘serpentine’ fibre – curly structures – which the body can more easily clear.

Asbestos still biggest cause of occupational cancer

As a result, clinical research has suggested that chrysotile fibres are not as likely to trigger cancerous cell activity and progress to the pleural cavity, where fatal mesothelioma tumours most commonly develop. Less congested lungs also mean that the body is more easily able to clear out the longest fibres. So while there is evidence that heavy and prolonged exposure to chrysotile can and does produce lung cancer, it is argued that low exposures may not necessarily present a detectable risk to health.

However, the official position of bodies such as the World Health Organisation (WHO) and the World Trade Organisation, is that while they recognise that the serpentine structure of white chrysotile is different from the amphibole type, nevertheless, it is still potentially a serious health hazard known to cause mesothelioma and asbestosis disease.

In June 2012, the British Journal of Cancer reported that “Asbestos continues to be the cause of the largest proportion of the overall burden of occupational cancer” and HSE have stated that while mesothelioma accounts for less than 1 per cent of all cancers, around 2,400 people continue to be diagnosed with mesothelioma in the UK every year.