Is chrysotile the main cause of 8 mesothelioma cases in Vietnam?

In 8 cases are diagnosed with mesothelioma by Japanese specialists, no case has clear history of occupational exposure to asbestos.

In reality, Health Environment Management Agency – Ministry of Health conducted a ministrial level study named “Study on asbestos-related diseases in exposure people” in three years (2009 – 2011). This activity is under the Project “Protection of workers’ health” for period 2009 – 2011 funded by the Japanese Ministry of Health, Labour and Welfare through the World Health Organization (WHO) and approved by the Government in the Document No. 525/TTg-QHQT dated April 8th 2009 and by the Ministry of Health in the Decision No. 2219/QĐ-BYT dated June 19th 2009. This study was accepted by the Medical Ethics Council of the Ministry of Health. Interview for occupational history provided 447 asbestos-related cases  (in 03 years 2009 – 2011 and these are asbestos-related diseases, including lung cancer, pleural thickening, and mesothelioma) taken into 06 big hospitals in study, among which 46 cases are diagnosed with pleural mesothelioma. Of 39 medical samples selected to be sent to Hiroshima Hospital, Japan, 08 cases are diagnosed with mesothelioma by Japanese specialists and no case has clear history of occupational exposure to asbestos.

(Ass. Prof., PhD. Tran Thi Ngoc Lan et al in Health Environment Management Agency. (2011) Study on asbestos-related diseases in exposure people, 2010 – 2011. Ministry of Health)

In fact, it is not really objective to equate all cases of mesothelioma in Vietnam to chrysotile exposure.

Firstly, the figure that 80% of mesothelioma cases are attributed to asbestos is provided in WHO report that derives from two statistic studies based on data of exposure to amphibole and chrysotile asbestos. Meanwhile, only chrysotile is allowed to use in Vietnam.

First study, “Asbestos, asbestosis, and cancer: the Helsinki criteria for diagnosis and attribution” (Scand J Work Environ Health 1997;23(4):311-316) confirms “80% of mesothelioma patients with more or less occupational exposure to asbestos.” However, the study also clearly stated: “Ignore some cases of mesothelioma with benign histologic types or those can not be determined clearly if it is malignant (…), all types of malignant mesothelioma can be caused by asbestos and cancer risk of amphibole is higher than that of chrysotile “.

Second study referred to the figure of 80% is “The epidemiology of mesothelioma in historical context” of J.C. McDonald, A.D. McDonald (Eur Respir J, 1996, 9, 1932 – 1942). The figure of 80% has even never appeared in this study, except in the sentence: “In early studies, a minority of male patients are attributed to occupational exposure to asbestos, while, the current ratio can be up to 90% depending on the location”. However, the study also emphasized that epidemiological studies have shown a significantly higher rate of mesothelioma in mines and factories that use amphibole asbestos due to its high biological durability. Furthermore, “Chrysotile used in industry often contains a low level of tremolite fibers (a type of amphibole), which could explain the small number of mesothelioma cases associated with this asbestos fibers [i.e chrysotile]”.

In fact, so far, science has not had an answer whether chrysotile causes mesothelioma or not. In the paper presented at the Technical Conference on Chrysotile held by the Secretariat for the Rotterdam Convention in Geneva on 30th –  31st of March, Dr. Dana Loom of IARC recognized that existing evidence showed that the ability of chrysotile to cause mesothelioma is less than that of amphibole – though the quality of data is limited.

Study in 1998 of Ilgren and Chatfield even concluded: “It is likelihood that no mesothelioma cases has ever been concluded, clinically and epidemiologically proven in any manufacturing industry such as cement, friction products, or textiles, where only chrysotile is used, with tens of thousands of workers”. (Ilgren and Chatfield. Indoor Built ENVIRON, 1998)

When non-governmental organizations implement health advocacy, it is groundless for them to consider the numbers of 107,000 people and 8 cases of mesothelioma in Vietnam as evidence of chrysotile-related diseases. The use of these figures to present at Workshops, Conferences on June 17th 2014, December 10th 2013, December 23rd 2014, April 22nd 2015, May 30th 2015; online talk on VOV on April 26th 2015; and interviews with newspapers such as VietNamNet, etc. lead to deviation of media cycle and public opinion and misunderstanding of the scientific results.