The use of AC roof sheet in Vietnam
There are 39 AC roofing facilities operating in Vietnam with the design capacity of 106 million m2/year which provide jobs for more than 5 thousand people.
Since 2008, the total production and consumption of AC roof sheets has been 80-85 million m2/year nationally, which accounts for 40-42% of total roof sheet market.
AC roof sheet is resistant to extreme weather condition condition; therefore, it normally will last from 30 to 50 years. Additionally, its price is only one-third of the price of 0.4 mm thick plated steel sheet and about 41-80% of the substitute roof sheets.
Presenting at the think-tank on “The use of chrysotile in Vietnam – some scientific and practical issues” in last June, Mr. Truong Minh Hoang – the National Assembly Deputy of Ca Mau province stated that “AC roof sheet is widely used in Mekong River Delta region and the mountainous areas. It is considered affordable and highly durable especially in alkaline environment, hoarfrost and salt water. The price of galvanized roof sheet is 40%-100% higher than the price of AC roof sheet. During transportation, the alkaline environment can damage the galvanized roof sheet in several months. Also, many people have drink rainwater running through AC roof sheets for decades”.
The risks of asbestos in drinking water from scientific perspective
Asbestos cement products only contain a small amount of chrysotile which ranges from 8 to 10%, the rest is the mixture of cement (55%) and natural coal (35%).
According to Associate.Prof Luong Duc Long, the Director of The Vietnam Institute of Building Materials – Ministry of Construction, due to the hollow structure of chrysotile fiber, the adhesives such as cement will fill the fiber creating a strong bond which is difficult to break or spread into environment.
In many countries, the asbestos cement is also applied to produce water pipes. By 1980, there were more than 3 million kilometers of asbestos cement water pipes used by countries such as Russia, Canada, Brazil and Thailand, etc.
Many studies have been conducted to evaluate the risks of chrysotile to human health in drinking water. The results have not found any evidences of chrysotile in drinking water causing cancer.
In 2002, the World Health Organization added in the report in 1996 on asbestos in drinking water and concluded that “available epidemiological studies do not support the hypothesis that an increased cancer risk is associated with the ingestion of asbestos in drinking-water. Moreover, in extensive feeding studies in animals, asbestos has not consistently increased the incidence of tumors of the gastrointestinal tract. There is therefore no consistent, convincing evidence that ingested asbestos is hazardous to health, and it is concluded that there is no need to establish a guideline for asbestos in drinking-water”.
In Vietnam, from 2010 to 2014, the Hospital of Construction – Ministry of Construction had implemented a study on the health status of people in Tan Trinh commune and other communes in Quang Binh district, Ha Giang province where 70% of people living in AC roofing houses. The studies was conducted in 1,046 households with total of 4,565 people.
The results have shown that the mortality rate in Tan Trinh commune was the lower than the average of the district. Especially, the cancer mortality rate of Tan Trinh ranked 5th out of 13 conmunes in the district but was still in normal range and lower than average.
The environment measuring results have not detected any chrysotile fiber in AC roofing houses.
The use of chrysotile around the world
The results of above researches are also consistent with the practical use of chrysotile in many countries such as Russia, Brazil, Thailand and Vietnam.
In Russia, Asbest city in Yekaterinburg province is one of the oldest chrysotile mining place in the world. Up to this point, the city has been established for 127 years and the total chrysotile reserves is expected to last 150 years more.
Due to geographic structure as well as its location close to the chrysotile mine, chrysotile can be found in many places in town from street to water. However, the locals have been living and working there for hundred years just like any other city in the world.
Mrs. Ustyugova Victoria Igorevna – The Deputy Director of the Hospital I shared that: the birth rate is 13.5% in 1,000 people ( in 2012, it was 15.3; in 2008, it was 13.2; in 2007, it was 12.9), the average rate of the region is 12.9% in 2009. Whereas, the mortality rate is 15.2% in 1,000 people which is lower than other cities in Russia. Hence, the birth and mortality rates are balance.
According to 2012 data, Brazil is the world leading country in chrysotile production and consumption with the annual mining of the largest mine being 300,000 tons. Currently, Brazilian people are still living normally despite that more than 60% of population drink water from chrysotile containing tanks and pipes.
In a study conducted by Doctor Ericson Bagatin on subjects in 6 different cities and living in AC roofing houses for at least 15 years. The results on 6,000 subjects only found 0.5% of pleural abnormalities in X-ray scan. Most of those abnormalities are non-asbestos related diseases such as unclear nodules, pulmonary tuberculosis, bronchiectasis, etc.
Kiều Anh