Sunday Times 2
Asbestos isn’t always harmful to health
Asbestos is a set of six naturally occurring silicate minerals.They are, thin fibrous crystals, with each visible fibre composed of millions of microscopic “fibrils”. Asbestos mining existed more than 4,000 years ago, but large-scale mining began at the end of the 19th century, when manufacturers and builders began using asbestos for its desirable physical properties: sound absorption, average tensile strength, resistance to fire, heat, electricity and affordability.
Sri Lanka uses only the ‘white chrysotile asbestos’ in our roofing sheet manufacture. All over the world, the only form of asbestos in commercial use is chrysotile, which is not harmful or hazardous to health. Hazardous blue and brown asbestos under poor worker safety conditions in the 20th century led to the understanding that asbestos dust inhalation from these forms can cause serious health concerns. As a result brown and blue asbestos varieties are banned globally.
However, chrysotile is used in over 140 countries – including the USA, Canada, Russia, India, China, Brazil, etc.
Over the last 50 years, world production of asbestos has not declined. The world production in 1960 was around two million tonnes, and still approximates to two million tonnes. However, while world production in the early 1960s included all major forms of the production of the hazardous amphibole varieties, crocidolite and amosite has ceased since 1987 and 1992 respectively.
Today, millions of workers are involved in international chrysotile asbestos industries. Taken together, these countries represent more than two-thirds of the total world population. For all parties of interest to be involved this means including and respecting the views of workers, their organisations, governments and industry.
Over the last three decades, there has been consistent published evidence that chrysotile can be used safely and under conditions that present no measurable risk to health. Many examples of safe use have been studied, noted, recorded and replicated at the factory, mine, regional and national level.
An investigation on 5,645 asbestos-cement manufacturing workers by Weill and others showed no raised mortality resulting from exposure for 20 years to chrysotile asbestos. The authors stated that,“The demonstration that low cumulative and short-term exposures did not produce a detectable excess risk for respiratory malignancy may be of assistance in the development of regulatory policy.”
Another follow up study of 2,167 workers employed in a factory manufacturing chrysotile asbestos cement products between 1941 and 1983 by Gardner and others showed no excess of lung cancers or other asbestos-related excess deaths.
Recent toxicology studies demonstrate that chrysotile asbestos has a relatively short bio-persistence and does not result in pathological response even through 90 days of exposure.
This explains what science affirms, that “chrysotile, which is rapidly attacked by the acid environment of the macrophage, falls apart in the lung into short fibres and particles.”
In the USA, the use of chrysotile has been attacked for many years by anti-asbestos lobbyists and various activists (including within the Environmental Protection Agency – the EPA) wherein they exerted great effort and enormous pressure to pass a full and total legislative ban. That effort did not succeed.
On October 18, 1991 the United States Fifth Circuit Court of Appeal was clear in its ruling when it refused this request based on a meticulous examination of scientific evidence, facts and the realities associated with risk – not conspiracies and conflated narratives.
The court struck down the crusade, and the EPA against the use of asbestos in the USA. The court concluded that the EPA failed to muster substantial evidence to support this abusive request.
In India, the Supreme Court dismissed the petition to ban the white chrysotile asbestos in the country as there was no evidence to prove that it was dangerous to human health. In January last year petitioners to the Supreme Court in India tried to use the same so-called scientific analysis to ban asbestos. The judges asked to see the evidence to support their petition but nothing was found. The petitioners were charged with perjury, and fined with a short custodial sentence.
The amount of airborne chrysotile fibres, atmospheric conditions etc. are the critical factors in determination of its health risk. In Sri Lanka, the National Building Research Organisation (NBRO) conducted an Air Quality Study on chrysotile fibre.
This study covered three different scenarios of chrysotile fibre exposure at a:
1. Chrysotile-cement roofing sheets production factory environment
2. Chrysotile-cement roofing sheets used house environment
3. Chrysotile-cement roofing sheets used construction or demolition site environment
The study was done in two factories. The first factory was located in Ratmalana. The second factory was located in Ja-ela.
The production technology is called “Hatschek technology”. The fibres are imported from Russia, Kazakhstan and Brazil.
For the household study, ten houses had been selected which used chrysotile cement roofing sheets which should be used for the roof, that should not be covered by a ceiling and they had different ages of roofing.
This study clearly showed that the ambient fibre levels are much below the Occupational Safety and Health Administration Standard of Permissible Exposure Limit (PEL) for asbestos in all three studies, which is 0.1 fibre per cubic centimetre.
The household environment showed the lowest levels of ambient fibres of chrysotile while construction sites showed the highest values of that.
According to the information provided by the factory management and the observations made at inspections, two factories are maintaining high level of safety to control possible emission and exposure to dangerous fibres.
All the fibre levels in this study were well below the threshold level.
To ban a substance, product, or natural resource implies that research, evaluation and serious study has taken place; and that prior to making a decision, that the overwhelming body of scientific evidence and policy options concludes there is no other possible choice but a ban. Such a decision is generally taken as a last resort, when other available policy options are ineffective in the face of a verified and dramatic threat.
The latest scientific evidence published internationally strongly supports the following views:
1. Chrysotile is significantly less hazardous than crocidolite and amosite, which is not imported to Sri Lanka.
2. When properly controlled and used, chrysotile asbestos in its modern day high-density applications does not present risks of any significance to public or workers’ health.
Today, a large number of countries use chrysotile fibres and products containing chrysotile and it is their firm intention to continue to do so in a safe and responsible manner.
Therefore, Sri Lanka should not ban the use of chrysotile asbestos as there is no scientific evidence of health risks.
(The writer is an emeritus professor of forensic medicine and toxicology at the University of Colombo.)