Background
Occupational carcinogens cause a considerable disease burden globally and at the national level [
1,
2]. In 2016, 349,000 deaths and 7.2 million disability-adjusted life years (DALYs) were attributed to occupational carcinogens. Asbestos is responsible for the greatest number of occupational cancer deaths [
3]. Although the health risks of asbestos were recognized early, the ban was implemented gradually and late [
4]. In 2007, the World Health Assembly Resolution 60.26 called for a global campaign to eliminate asbestos-related diseases [
5]. To date, 67 of 195 countries around the world have banned asbestos [
6]. Asbestos is still being produced and exported in major producing countries such as Brazil, China, Kazakhstan, and Russia [
7].
Asbestos refers to six naturally occurring fibrous minerals: amosite, actinolite, anthophyllite, chrysotile, crocidolite, and tremolite [
8], and it is used for insulation in buildings and as an ingredient in a number of products. Exposure to asbestos causes cancer of the lung, larynx, ovaries, and mesothelioma, as well as asbestosis. According to the World Health Organization (WHO), 125 million people worldwide are exposed to asbestos at work. At least 90,000 people die each year from asbestos-related lung cancer, mesothelioma, and asbestosis, according to global estimates [
5].
Brazil, China, Kazakhstan, and Russia account for more than 90% of the world's total asbestos production [
9]. In this study, we present results from the Global Burden of Disease (GBD) 2019 and provide an assessment of current trends of disease burden attributable to asbestos in Brazil, China, Kazakhstan, and Russia between 1990 and 2019. These countries need to be made aware of the burden of asbestos to implement a ban as soon as possible.
Discussion
The International Commission on Occupational Health calls for a global ban on the mining, sale, and use of all forms of asbestos to eliminate asbestos-related diseases [
13]. The production and use of asbestos has been reduced or banned in many countries, although some countries continue to produce or consume the material. The estimated global production of asbestos in 2020 was 1.2 million tons; the top four producing countries are Russia (790,000 tons), Kazakhstan (210,000 tons), China (100,000 tons), and Brazil (60,000 tons). In recent years, worldwide consumption of asbestos fiber is estimated to have decreased from roughly two million tons in 2010 to about one million tons per year [
7]. China and Russia are the biggest users. Most of the deaths in high-income areas are caused by carcinogens, and asbestos-related cancers account for approximately 80% of all cancer deaths in these areas [
14]. In low and middle income countries, exposure to asbestos still occurs, which may have a devastating effect if current and future exposure is not controlled.
Asbestos is used as insulation in buildings and in a variety of consumer products, such as water supply lines, roofing shingles, gaskets, and clutches and brake linings [
5]. It is expected that asbestos-cement products, such as pipes, corrugated roofing tiles, and wall panels, will continue to be the world's dominant asbestos market. Even after demolitions, renovations, or destruction of asbestos-containing materials, asbestos can still be found in buildings and in the environment. This legacy asbestos may also be a risk to the general population [
4,
15]. There are thousands of deaths linked to asbestos exposure in homes.
The present findings indicate that the burden of disease attributable to asbestos is on a downward trend globally. The number of deaths are higher in men than in women, and the age-specific mortality rate is higher in men than in women. This may be related to a male predominance among workers. The mortality rates are high in the elderly, which is consistent with previous results. Because asbestos-related diseases have long latency periods, the number of asbestos-related deaths will not decrease immediately after the use of asbestos is discontinued [
5]. Even in countries that banned asbestos in the early 1990s, asbestos-related diseases continue to increase.
In this study, we showed that TBL cancer was the leading cause of death and DALYs attributable to asbestos between 1990 and 2019 globally and in Brazil, China, Kazakhstan, and Russia, followed by mesothelioma. Although the ASMR and ASDR of TBL cancer attributable to asbestos decreased in recent years, the decrease is not obvious in China and Russia. China and Russia should pay special attention to screening for TBL cancer.
Although China’s disease burden attributable to asbestos is relatively low compared with that in Kazakhstan and Russia, China showed the highest percentage change and EAPC in ASMR and ASDR related to exposure to asbestos between 1990 and 2019, especially in men. According to China’s Ministry of Industry and Information Technology, the mining and processing of chrysotile requires workers to wear protective clothing since 2014 [
16]; however, chrysotile is not completely banned. Asbestos should also be restricted and eventually banned by the Chinese government. The ASMR and ASDR of disease attributable to asbestos is stable in Brazil. Although asbestos was banned nationwide in Brazil in November 2017, the government of the state of Goias passed a law that permitted asbestos mining in the state for export in July 2019, and asbestos is still produced in Brazil. It is predicted that China and Brazil will face a public health crisis on an unprecedented scale caused by the use of asbestos [
17]. Kazakhstan was the fourth-largest producer of asbestos, although the ASMR and ASDR of disease attributable to asbestos have been decreasing in Kazakhstan. The WHO started to support Kazakhstan's efforts to eliminate asbestos-related diseases in 2011. However, the government of Kazakhstan has never banned asbestos, and diseases are estimated to be under-reported by a large margin. The global economy still encourages asbestos production and use in Russia [
18]. Uralasbest runs the world’s largest operating chrysotile asbestos mine in Russian Federation [
19]. Although Russia does not have the highest disease burden of asbestos in 2019, these are particularly troubling result. In fact, according to the WHO, mining and exploitation of minerals is the most effective method to eliminate diseases attributable to asbestos. It is time to ban asbestos completely around the world.
The present study had several limitations. First, the risk cannot be quantified because epidemiological studies lack accurate exposure information. Second, the GBD results are based on the estimates obtained by combining the system dynamics model and the statistical model, which does not constitute real observation data, and the estimated results could be inaccurate. Furthermore, the prevalence of asbestos may be underestimated in low income countries with poor health supervision systems.
Conclusion
This study assessed the disease burden attributable to asbestos in Brazil, China, Kazakhstan, and Russia. Although the burden of disease attributable to asbestos declined globally, it remains highly heterogeneous in Brazil, China, Kazakhstan, and Russia. TBL cancer is the leading cause of death and DALYS attributable to asbestos. There has been an increasing trend in mortality and DALYs in China, especially in older men. We call for a global ban on asbestos, especially in Brazil, China, Kazakhstan, and Russia.
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