The Chamber of Construction Industry Sri Lanka (CCI), the apex body which represents all the construction industry stakeholders in Sri Lanka held a special seminar on “Facts about the use of ASBESTOS – Chrysotile Cement Roofing” at the Taj Samudra Hotel. Taking in to consideration the call to ban all asbestos related products in Sri Lanka, the CCI as the responsible main representative of the construction industry brought together both international and local experts to discuss various aspects pertaining to the issue.

The event was supported by the Chrysotile Information Centre. The Chrysotile Information Center is a non-profit organization established to provide scientific information, public education and assistance in relation to the responsible and safe use of Chrysotile. It provides objective information, trainings and seminars to workers, manufacturers, members of the public, governments and other relevant stakeholders regarding best practices for Chrysotile fiber handling and usage. The center also advocates for the mandatory inclusion of safe use programs, and works closely with local manufacturers and relevant government/regulatory bodies to raise awareness about the need for and benefits of safe use. It has presence in Thailand, Malaysia, Vietnam, Laos, Cambodia, the Philippines, Sri Lanka and Pakistan.

Speaking on the decision to hold the seminar, Secretary General/Chief Executive Officer of the CCI Eng. Nissanka N. Wijeratne notes, “As the representative of the construction industry in Sri Lanka the CCI is concerned about the adverse effects a blanket ban of asbestos related products could have on our industry stakeholders without a proper evaluation on the health and economic impacts. Therefore we are bringing together internationally renowned experts together with the experts in Sri Lanka to carefully evaluate all aspects of asbestos usage, safety measures and alternatives etc. both internationally and locally. We are indeed privileged to have several renowned speakers at our seminar at which we hope to shed significant light on the usage of Chrysotile asbestos, Sri Lanka’s position and a scientific study of risks vs. economic use.”

Dr. David M Bernstein Ph.D. a world renowned toxicologist will deliver a comprehensive address on “Health risks of Chrysotile revisited”. Dr. Bernstein has over 35 years of experience in the conduct of inhalation toxicology studies with pharmaceuticals and chemicals and in the evaluation of their toxicological effects. Meanwhile the legal advisor of the International Chrysotile Association Emiliano Alonso will discuss the “WHA/WHO’s position on Chrysotile”. During the second session of the seminar, Dr. Vivek Chandra Rao a senior medical professional from India will bring facts and figures from closer to home in his speech on “The current regulations and situation in India”. The final topic of discussion of the seminar will be “Alternatives to Chrysotile Cement Roofing” which will be presented by Professor S.M.A. Nanayakkara, Professor of Civil Engineering at the University of Moratuwa.

Understanding of the health risk from Chrysotile Asbestos as used today in high density cement products

• Very frequently, amphibole asbestos (Amosite, Crocidolite) was mixed with Chrysotile in past manufacturing processes and usage – thus resulting in a mixed fiber experience.
• In the past, it is essential to note, that there was little or no attempt to differentiate exposure to these two very different minerals and this has had a critical impact in terms of health effects and perception. 

Chrysotile

• Chrysotile is a rolled sheet material like mica.
• The sheet is about 8 angstroms (0.8 nanometers) thick and because of molecular constraints, is rolled into cylindrical form.
• The cylinders are Chrysotile fibrils which bunch together to form a Chrysotile fiber.
• The Chrysotile fiber is acid soluble (von Kobell, 1834; Pundsack, 1955).
• In acid the rolled sheet of the Chrysotile fiber breaks apart into small pieces.
• This is important: In the lung – the cell which clears fibers and particles from the lung – the macrophage – creates an acid environment. 

Amphiboles

• The amphibole asbestos class of fibers is formed as solid rods/fibers (Skinner et al., 1988).
• The structure of an amphibole makes it very strong and durable.
• The external surface of the crystal structures of the amphiboles is quartz‐like, and has the chemical resistance of quartz.
• Amphibole fibers, therefore, have negligible solubility at any pH that might be encountered in an organism (Speil and Leineweber, 1969). 

Why do some fibers cause disease?

• Fiber dimensions (length and diameter)
• Fiber biosolublity (durability)
• Fiber dose 

What does toxicology say about these two minerals?

• The more recent toxicology studies demonstrate that;
  • Chrysotile asbestos has a relatively short bio persistence and
  • Does not result in pathological response even in a sub‐chronic inhalation toxicology study at an exposure concentration 5,000 times greater than the US Threshold Limit Value of 0.1 f (WHO)/cm3.
  • Following such exposures, Chrysotile asbestos produces neither a pathological response in the lung nor in the pleural cavity.
  • In addition, the Chrysotile fibers clear rapidly from the lung and are not observed at the visceral pleural surface, in the pleura nor on the parietal pleural surface.
  • However with Amphibole fibers in the lung, immediately following a 5 day exposure, the amphibole fibers have been shown to produce extensive inflammation with pathological lesions.
  • Within 28 days after the 5 day exposure, interstitial fibrosis was observed in the lung.
  • The amphibole fibers are poorly cleared from the lung with the longer fibers longer persisting through the life‐time of test rats.
  • Within 2 weeks after the 5 day exposure, amphibole fibers were:
    • observed penetrating through the visceral pleural surface and
    • were associated with extensive inflammation and fibrotic development in the pleura.
    • These pathological changes parallel closely those in humans who develop mesothelioma. 

Proposed Substitutes

• The Report of the World Health Organization workshop on Chrysotile asbestos substitutes, has clearly reported that there is very little scientific basis for the evaluation of the proposed substitutes for Chrysotile.
• For many of the fiber types, the limited data available would suggest that they should be of considerably greater concern than Chrysotile. 

Conclusions

• The scientific evidence recently published, as shown by
  • cohorts studies;
  • epidemiological reviews and
  • inhalation toxicology studies,

provides strong support that Chrysotile is significantly less hazardous than the amphibole forms of asbestos (e.g. crocidolite and amosite).

• With proper control and use, Chrysotile asbestos in its modern day high‐density cement applications does not present an excess risk of either:
  • lung cancer or
  • mesothelioma of any significance to public and/or worker health.