Following the 2016 Cabinet decision to control the use of asbestos, numerous discussions and dialogues were held on and off the mainstream media concerning the pressing matter.
As a widely popular roofing material used by majority of the populace in the country, it is important to take a look at the true nature of this material and whether it has the potential to cause health hazards as presumed.
Asbestos is the commercial name given to a naturally occurring fibrous mineral. In the past, asbestos reigned the construction world as one of the most versatile materials. Today, the name has earned a negative image, facing a barrage of criticism on potential health hazards. However, there is a common misconception among many that the material asbestos is a single element, but this is far from the reality.
Asbestos is categorized into two distinct groups – serpentine and amphibole. The serpentine group consists of chrysotile fibres, while the amphibole group further divides into five distinct fibre types namely crocidolite, amosite, anthophyllite, tremolite, and actinolite. In other words, asbestos is in fact a naturally occurring fibrous material comprising a set of six distinct minerals.
According to the International Chrysotile Association (ICA), which released its latest collection of research papers titled ‘Compilation: Recently published studies in Chrysotile fibres – 2016’, several comprehensive studies conducted on the toxicology (the study of the nature, effects, and detection of poisons and the treatment of poisoning) and epidemiology (the branch of medicine that deals with the
study of the causes, distribution, and control of disease in populations) of the two types of mineral groups.
Solubility is one of the key factors of a mineral which determines its toxicity and potential health effects. A study on ‘Biopersistence’ – analyses the fibres’ solubility nature in the lung, and the lung’s ability to clear the external elements out of the system. Accordingly, ICA clarifies that based on biopersistence studies as well as ‘sub-chronic inhalation toxicology’ studies, chrysotile fibres at highly concentrated exposure (of up to 5000 times the current threshold limit value – 0.1 fibres per cubic centimetre), caused no pathological response. Moreover, chrysotile fibres are soluble in lungs, and does not reach pleural cavity.
However, when the same tests were conducted on amphibole asbestos fibres, the results were highly pathogenic (potential for causing disease) and even produced interstitial (space between organs/tissues) fibrosis as well as pleural inflammation. In addition, it was also observed that fibres had the potential to move to the pleural cavity. This is mainly due to the amphibole fibres being least soluble in the lungs.
Conversely, chrysotile asbestos fibres displayed very low biopersistence, while the amphibole asbestos fibres displayed a very high level of biopersistence. ICA research papers further stressed that chrysotile asbestos produce negligible health effect in comparison to amphibole asbestos and under controlled conditions, it can be used safely. On the other hand, amphibole asbestos comprising solid silicate fibres with negligible solubility and high biopersistence holds higher potential in causing diseases even with short-term exposure.
At present only chrysotile fibres are used in commercial applications in Sri Lanka, and they are used in the manufacture of high density roofing sheets. Comprehensive tests have been conducted globally on biopersistence studies and sub-chronic inhalation toxicology studies where they have clearly shown that under controlled conditions, chrysotile can be used safely. Chrysotile fibre roofing industry has successfully served the nation for more than 70 years. Therefore, it’s crucial to consider the impact on the industry and the populace of the country in the long run, if the regulatory decisions were to be implemented.