The word asbestos is a commercial term to indicate any fibrous mineral with a fibrous form. In fact, there are many types of asbestos fibres which are divided into two families based on their differences in physical/chemical properties: the serpentine(white asbestos fibre) and the amphiboles (blue and brown asbestos fibre)
Amosite, crocidolite, tremolite, actinolite, and anthophyllite are all amphibole type of asbestos fibre, which is straight and needle-like and has a long half-life. Once in the human lung, amphibole fibre could cause tumors and inflammation symptoms. After 10 to 20 years of incubation, the tumor will develop into cancer and other lung related diseases.
The serpentine fibre group, including chrysotile asbestos (or white asbestos), is curly and soft, which makes it the only approved type of asbestos to be commercialized today – most commonly for industrial purposes. The group is put under the list of low biopersistent chemicals, much lower than glass wool fibre. According to scientific researches, after entering human body via inhalation, chrysotile fibre will be disposed from the lung in 0,3 to 11 days or decomposed by the acid environment created by the macrophage.
Chrysotile: Worldwide and in Vietnam
Currently, the amphibole asbestos has been globally banned under any form because the poor working condition and wrong uses of asbestos such as spraying in the past caused the transmission of the fibre into the air, which leads to occupational lung diseases. Asbestosis patients recently found were the result of the amphibole asbestos exposure 20 to 40 years ago.
However, chrysotile is still used under strict control in many countries all over the world, including G8 countries: the U.S, Russia and other countries such as: Mexico, Brazil, Ukraina, Kazakhstan, Kyrgyzstan, Uzbekistan, China, India, Thailand, Singapore, Indonesia, Vietnam…
Not only scientific researches in Vietnam but also worldwide have not found any evidence of diseases caused by chrysotile. All the researches emphasized the impact on human health of each type of asbestos fibre is different due to the dissimilarities in physical and chemical characteristics between the two groups of asbestos. The research of Hodgson and Darnton (2000) showed that the risk of disease when being exposed to amphibole asbestos are significantly higher than to chrysotile asbestos:
|Risk of disease||Chrysotile||Amosite||Crocidolite|
The research on asbestos related diseases in exposed cases implemented in 3 years from 2009 to 2011 by Vietnam Health and Environment Management Agency (VIHEMA) – Ministry of Health – is under the “Workers’ Health Protection Project” funded by Ministry of Health, Ministry of Labour, Invalids and Social Affairs and Japan via the World Health Organization (WHO). The research, conducted on 447 cases in 6 hospitals (the patients has asbestos related diseases, including lung cancer, pleural thickening and mesothelioma, in 3 years from 2009 to 2011), showed that there were 46 cases diagnosed to have pleural mesothelioma. 39 samples sent Hiroshima Hospital were confirmed by Japanese specialists to have mesothelioma but none of the sample has a clear history of being occupationally exposed to asbestos.
Source: VIHEMA. (2011) Research on asbestos related diseases in exposed cases, 2010 – 2011. Ministry of Health
The result of workers’ health monitoring – implemented from 1976 until now – shows only 4 cases of occupational asbestosis over 28.000 occupational disease cases covered by insurance. Compared with the 20.000 cases of silicosis cases caused by silica exposure (accounting for 75% of total occupational disease cases covered by insurance), 4 cases of asbestosis are just minor number. Other asbestos related diseases such as lung cancer, pleural mesothelioma have not been detected by any periodical health check or occupational health check for workers in fibro cement roofsheet industry.
Safe use of chrysotile
Since all countries are heading toward a safe and controlled way of using chrysotile in production, only products with high concentration of chrysotile are approved to be produced in order to meet the requirement of safety for health of society and to protect the environment. Over 90% amount of chrysotile fibre over the world is used in the production of construction materials containing chrysotile – cement compounds.
The production of fibro cement sheet and pipe contains low amount of chrysotile fibre (from 8 to 10%), while the percentage of other raw materials is: 55% of cement, 35% of natural coal ash. The chrysotile fibre, having hollow structure, connected strongly to the cement particles in the whole production process, which makes it hard to be emitted to the environment. Despite the safety from the structure of the chrysotile itself, eliminating the emission of chrysotile fibre is still a serious concern for all the chrysotile related businesses today. As a matter of fact, factories and mines are currently using moist and closed technology minimizing the fibre emission to the air. Therefore, risks of community health and environment have been reduced drastically.
The fibro cement roofsheet industry in Vietnam has presented for over 50 years – since 1963 – and developed into an industry having 39 factories with designed production capacity of over 106 million m2 /year and over 5.000 workers. Since 2008, the industry has produced and consumed annually 80 – 95 million m², accounting for 60 – 62% the demand of roofsheet. 60.000 – 70.000 tons of chrysotile have been used each year in the production. The AC roofsheet can resist severe weather, be long lasting (30 – 50 years), have cheap price (1/3 the price of the pre-painted galvanised iron 0.4mm thick sheet and 41.5 – 80.6% cheaper compared to sheet using alternative fibre).
Nowadays, there are many campaigns calling for the supports to a global ban of chrysotile regardless of scientific researches and useful applications of this fibre. Unfortunately, the activists are working both through official actions as well as unofficial ones, which in many cases lacks of clarity. The purposes of those campaigns are not totally for the community health but for other reasons such as commercial competition in order to replace the 40% market share of chrysotile in Vietnam with PVA fibre or galvanized iron sheets. Especially, many organizations and individuals have received significant profit from anti-chrysotile activities such as attorney fee, incentives from compensation to patients attending lawsuits.