Asbestos use and asbestos-related diseases in Asia: Past, present and future
Ken Takahashi, Department of Environmental Epidemiology, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Iseigaoka 1-1, Yahatanishiku, Kitakyushu City, Fukuoka Prefecture 807-8555, Japan. Email: firstname.lastname@example.org
Background and objective: Although there are growing concerns about the global epidemic of asbestos-related diseases (ARD), the current status of asbestos use and ARD in Asia is elusive. We conducted a descriptive analysis of available data on asbestos use and ARD to characterize the current situation in Asia.
Methods: We used descriptive indicators of per capita asbestos use (kilograms per capita per year) and age-adjusted mortality rates (AAMR, persons per million population per year) by country and for the region, with reference to the world.
Results: The proportion of global asbestos use attributed to Asia has been steadily increasing over the years from 14% (1920–1970) to 33% (1971–2000) to 64% (2001–2007). This increase has been reflected in the absolute level of per capita use across a wide range of countries. In contrast, 12 882 ARD deaths have been recorded cumulatively in Asia, which is equivalent to only 13% of the cumulative number of ARD deaths in the world during the same period. The highest AAMR were recorded in Cyprus (4.8), Israel (3.7) and Japan (3.3), all of which have banned asbestos use.
Conclusions: There is a paucity of information concerning the current situation of ARD in Asia. The marked increase in asbestos use in Asia since 1970, however, is likely to trigger a surge of ARD in the immediate decades ahead.
The World Health Organization (WHO) recognizes that asbestos is one of the most important occupational carcinogens, and the burden of asbestos-related diseases (ARD) is rising. The WHO declared the need to eliminate ARD and cease asbestos use.1 Recently the WHO upgraded its global estimate of ARD to 107 000 annual deaths caused by asbestos-related lung cancer, mesothelioma and asbestosis.2 A 2005 study of disease burdens due to occupational carcinogens estimated a worldwide incidence of 43 000 mesothelioma cases, and 27 000 were attributed to the Asia-Pacific region.3 Despite Asia's growing importance in the world, objective analyses concerning its asbestos use and ARD have been scarce.
The asbestos situation in Asian countries was described following a 2002 regional conference, which was the first to discuss the theme.4 A striking feature of the region was the persistent use of asbestos in most, if not all, countries; however, important changes have occurred since that time. Indeed, Japan, which was a major asbestos user, experienced the ‘Kubota Shock’ (media exposure of a cluster of ARD victims impacting society)5 in 2005 and adopted a total asbestos ban in 2006 (a prohibition in principle was already in effect in 2004). In addition, Korea promulgated a ban, in principle, in 2006 and a total ban in 2009 after recognizing a surging number of mesothelioma cases.6 Moreover, we are aware that several south-east Asian countries are considering asbestos bans, although this information has not been documented. Thus, the asbestos situation in Asia is volatile and warrants a careful description.
A nation's status with respect to asbestos and ARD can be described in comparative terms using macro-indicators such as per capita asbestos use and age-adjusted mortality rates (AAMR). The volume of asbestos used per capita (per capita asbestos use) is a surrogate for the exposure level of a population, and its trend over time has been used to characterize the asbestos situation of various populations.7,8 In addition to other studies9,10 we have used per capita asbestos use to estimate or predict ARD in different populations, and this method has produced plausible findings.11,12 In the present study, we conducted a descriptive analysis of the available data to characterize the situation in Asia. We assumed that a country's past asbestos use influenced the present ARD rates, and that present use of asbestos will influence future ARD.
We identified all countries that have available data for either asbestos use and/or mortality data for ARD. From a total of 185 countries identified, we adopted the definition of Asia by the United Nations Statistics Division13 and identified 47 countries that belonged to Asia. These 47 Asian countries were analysed in our study with reference to the 185 countries in the world.
We extracted all data on asbestos use from a related report of the United States Geological Survey (USGS).14,15 We adopted the USGS definition of use (production plus import minus export),14 the data for which were available by country in 10-year intervals from 1920 to 1970, 5-year intervals from 1970 to 1995 and annually from 1995 to 2007. We treated a reported negative value of asbestos use (caused by storage, for example) as zero in the present analysis. When necessary, we interpolated values for asbestos use for the calendar years lacking data.
Using the WHO Mortality Database,16 we identified the number of deaths recorded as ‘mesothelioma (C45, International Classification of Diseases, 10th Revision, or ICD-10)’,17 or any subcategories thereof, and ‘asbestosis (J61, ICD-10)’ between 1994–2008. We separately counted numbers recorded for ‘malignant neoplasm of the pleura (163, ICD-9)’17 as a condition generally synonymous with mesothelioma of the pleura. To investigate countries that did not report data to the WHO, we used PubMed (http://www.ncbi.nlm.nih.gov/pubmed) and other sources to search for national frequency data published in English (only 2 such references18,19 could be identified).
National population data from 1920–2008 were obtained from the WHO,16 the United States Census Bureau20 and Lahmeyer,21 and the data were prioritized for use in this order. We used the indicators of per capita asbestos use (measured in kilograms per capita per year (kg/capita per year)) and AAMR (measured in cases per million population per year) to analyse the national situations for asbestos and ARD, respectively. AAMR were calculated using a direct age-adjustment method with reference to the world population in the year 2000.22
Asbestos use data for Kazakhstan required special treatment because of its political transition since the era of the Soviet Union. Because data on asbestos use for the Soviet Union between 1920–1990 in the USGS database represented Russia and Kazakhstan combined,14 we apportioned the data from this time period between Russia and Kazakhstan according to the ratio of use recorded by Russia and Kazakhstan between 1995–2007. In the present analysis, only data for Kazakhstan were used because Kazakhstan is categorized as a part of Asia by the U.N. Note that the observed period for asbestos use was 1920–2007 and that for ARD mortality was 1994–2008 due to the availability of data in the respective databases.
We compiled all data and conducted descriptive statistics using Microsoft Excel (Microsoft Corporation, Redmond, WA, USA). We extracted the numbers of deaths recorded in the WHO Mortality Database and calculated the AAMR using SAS Version 9.1 (SAS Institute Inc., Cary, NC, USA). Graphs were created with Sigmaplot Version 9.01 (Systat Software Inc., San Jose, CA, USA), and maps were drawn using MapInfo Professional Version 7.5 SCP (Schlosser Geographic Systems, Inc., Seattle, WA, USA).
Table 1 summarizes the asbestos situation of the 47 analysed countries as a region and by groups of countries according to the availability of data for asbestos use and ARD mortality: group A consisted of 30 countries with available data for asbestos use only, group B consisted of 15 countries with available data for both asbestos use and ARD mortality, and group C consisted of two countries that only had available data for ARD mortality. In Asia, the asbestos use totaled 55.5 million metric tons (tons, hereafter) during the observed period of 1920–2007 (29% of the world's use). For the three consecutive periods observed, Asia accounted for 14% (1920–1970), 33% (1971–2000) and 64% (2001–2007) of the world's asbestos use. The annual mean volume of asbestos use for each period was 0.1, 0.9 and 1.2 million tons in group A, and 0.08, 0.4 and 0.1 million tons in group B, respectively.
Table 1. Asbestos use and asbestos-related diseases (ARD) in Asian countries and the world
|Asbestos, recorded cumulative use (million metric tons)|
| During 1920–1970||5.1 ||3.9 ||NA||9.0 ||65.4 |
| <annual mean>||<0.1>||<0.08>||(13.8)|
| During 1971–2000||25.6 ||11.6 ||NA||37.2 ||113.7 |
| <annual mean>||<0.9>||<0.4>||(32.7)|
| During 2001–2007||8.4 ||0.9 ||NA||9.3 ||14.6 |
| <annual mean>||<1.2>||<0.1>||(63.7)|
| Total||39.1 ||16.4 ||NA||55.5 ||193.7 |
|ARD, reported cumulative mortality during 1994–2008 (n of cases)|
| ICD-10, C45||NA||12,011 ||1 ||12,012 ||92,253 |
| ICD-9, 163||NA||53 ||1 ||54 ||330 |
| ICD-10, J61†||NA||516 ||0‡[NA]||516 ||9,943 |
| Other data source§||NA||300 ||0¶[NA]||300 ||868 |
| Total||NA||12,880 ||2 ||12,882 ||103,394 |
In terms of ARD, 12 882 ARD deaths (12 012 were mesothelioma (ICD-10, C45)) have been recorded cumulatively in Asia, which is equivalent to 12.5% of ARD deaths (13.0% of mesothelioma (ICD-10, C45)) worldwide. Except for a single case of mesothelioma and another case of malignancy of the pleura belonging to group C, all cases belonged to group B: mesothelioma in 10 countries, malignancy of the pleura in four countries, asbestosis in five countries, all of which were recorded in the WHO Mortality Database, and mesothelioma in 1 country, which was identified in the scientific literature (and not recorded in the WHO Mortality Database).
Table 2 shows situations asbestos use and/or ARD mortality by country. In terms of per capita asbestos use, five countries recorded high values (defined as exceeding 1.0 kg/capita per year) between 1920–1970: Cyprus (7.6), Kazakhstan (5.8), Israel (3.2), Lebanon (2.1) and Singapore (1.5). Thirteen countries recorded high values between 1971–2000: Kazakhstan (18.4), U.A.E. (3.4), Kyrgyzstan (3.1), Cyprus (2.4), Japan (2.2), Thailand (1.7), Korea (1.5), Uzbekistan (1.5), Malaysia (1.4), Singapore (1.3), Saudi Arabia (1.2), Lebanon (1.1) and Kuwait (1.0). Five countries recorded high values between 2001–2007: Kazakhstan (11.4), Kyrgyzstan (4.2), U.A.E. (3.5), Thailand (2.1) and Uzbekistan (1.9). Among these countries, Kazakhstan was the only country listed with high values during all three consecutive periods. Cyprus and Lebanon had high values for the two earlier periods and Kyrgyzstan, U.A.E., Thailand and Uzbekistan had high values for the two latter periods. Four countries increased their use over the three periods: Thailand, China, India and Indonesia. In total, most Asian countries (28/47 or 60%) increased asbestos use during the observation period (Table 2 and Fig. 1).
Table 2. Age-adjusted mortality rate (AAMR) of asbestos-related diseases (ARD) between 1994–2008 and per capita asbestos use (kg/capita per year) in Asian countries
| 4||Bahrain||C||—||—||—||3.46 (1)||—|
| 9||Cyprus||B||7.60||2.41||0.12||4.79 (4)||—|
|10||Georgia||B||—||0.00||0.01||0.33 (3)||0.38 (2)|
|11||Hong Kong||B||0.02||0.04||0.20||1.19 (7)||0.20 (5)|
|16||Israel||B||3.19||0.56||0.02||3.67 (10)||0.13 (5)|
|17||Japan||B||0.80||2.23||0.17||3.25 (14)||0.12 (14)|
|32||Philippines||B||0.07||0.04||0.03||0.21 (5)||0.08 (5)|
|34||Republic of Korea||B||0.32||1.45||0.28||0.62 (12)||0.03 (7)|
|37||Sri Lanka||B||—||0.37||0.81||0.27 (1)††||—|
|44||United Arab Emirates||A||—||3.43||3.46||—||—|
|45||Uzbekistan||B||—||1.45||1.89||0.30 (2)||0.03 (1)|
In terms of ARD, 17 and 7 countries reported data for at least 1 year for mesothelioma and asbestosis deaths, respectively (the numbers of countries reporting data for at least 3 years are 11 and 5, respectively). Among countries reporting data for at least 3 years, the AAMR (cases per million population per year) for mesothelioma were highest for Cyprus (4.8), Israel (3.7) and Japan (3.3). It should be noted that the AAMR values for Bahrain and Macau, which were the two countries in group C, were each based on a single case in a single year.
Figure 2 illustrates temporal trends of asbestos use in combination with or without mesothelioma mortality (depending on data availability of the latter) in selected countries. Peak asbestos use in Japan exceeded 2.0 kg/capita per year between 1970–1990, which was followed by a linear increase of mesothelioma mortality since 1995 and the rate has recently approached 4 per million population per year. In Korea, asbestos use reached a peak just below 2.0 kg/capita per year between 1975–1995, which was followed by an increase in mesothelioma mortality that has slowly risen since 1995 and recently approached 1 per million population per year. Singapore recorded a sharp, transient peak of asbestos use around 1975 (approaching 4.0 kg/capita per year), which was followed by an increase in mesothelioma mortality leaping from less than 0.5 to recently around 2.0 per million population per year. Asbestos use in Thailand increased in the 1960s, exceeded 1.0 kg/capita per year in 1975 and peaked at around 3.0 kg/capita per year in 1996. Recently the level of asbestos use in Thailand has fluctuated. China and India have shown increased asbestos use approaching 0.5 and 0.3 kg/capita per year, respectively, and the slopes have recently accelerated. Thailand, China and India, however, lack national data on mesothelioma.
Table 3 highlights the national policy situations in Asia related to asbestos use with reference to the world. Only 3 (6%) Asian countries have ratified the International Labour Organization (ILO) Asbestos Convention23 compared with 17% of countries worldwide. Thirteen (28%) Asian countries have adopted asbestos bans, which is a similar percentage to the number of countries that have adopted asbestos bans worldwide (30%).
Table 3. Ratification status of the International Labour Organization (ILO) Asbestos Convention† and adoption of asbestos ban‡ in Asia and the world
|Ratification status of ILO Asbestos Convention†||6.4% (3‡/47)||17.3% (32/185)|
|Adoption of asbestos ban§||27.7% (13¶/47)||29.7% (55/185)|
Before 1970, Asian countries only accounted for a minor proportion (14%) of global asbestos use. This historical situation should be reflected, at least partially, in the current situation of ARD, for which only 17 (36%) of the 47 analysed countries recorded ARD deaths. Interestingly, only about 13% of global ARD deaths have occurred in Asia. These figures are low for a region with a combined population of 3.7 billion, or 61% of the world's population in the year 2000.
The asbestos situation has changed drastically since Asian countries increased their share to 33% of the world's use between 1971–2000, which reached 64% after the turn of the century. Although the delineating year of 1970 was chosen arbitrarily, it represents a widely accepted latency time of 30–50 years for ARD,25,26 particularly mesothelioma, to develop at the individual (case) level after asbestos exposure. The year 1970 is also in line with our earlier findings at the national level, that asbestos use between 1960–1969 correlated with ARD mortality rates around the year 2000.11 In addition, cumulative asbestos use before 1970 predicted the recent cumulative number of mesothelioma deaths.27 Thus we hypothesize that the increased asbestos use observed after 1971 will begin to take its toll.
In the present study, we observed characteristic trends within groups and in individual countries. Group B countries (i.e. countries with available data for asbestos and ARD) had substantially reduced asbestos use since 2001 (the average annual mean was 0.1 million tons), whereas group A countries (i.e. countries with available data for asbestos only) had substantially increased asbestos use during the same period (the average annual mean was 1.2 million tons). Similar trends were observed at the level of individual countries, which suggested that countries reduced their asbestos use after realizing the burden of ARD. Although the reduction of asbestos use may correlate with a country's own acquisition of ARD data, the ‘lessons’ of other countries are not easily learned.
Western countries that used large volumes of asbestos eventually experienced an epidemic of ARD,28 typically mesothelioma. At the national level, this experience can be demonstrated graphically as the ‘double-peak’ curve,29,30 in which the ARD epidemic curve follows the asbestos-use curve after several decades.6 Several Asian countries are now following this pattern: Japan (most typical; Fig. 2A), Korea (typical; 2B), Singapore (possible; 2C) and Israel (possible; not shown). In these countries, the initial, rising segment of the presumed ARD curve coincides with the final waning segment of the asbestos-use curve.6 Furthermore, the slopes of the rising segments of both curves appear similar in their respective countries. These findings suggest that countries will experience ARD even after asbestos use is significantly decreased and in a manner reflective of historical asbestos use.
It is highly unlikely that ARD are absent in countries that have used large volumes of asbestos but do not report the related numbers.27,31 In Asia, this problem is especially relevant to China (Fig. 2E) and India (2F), where levels of asbestos use have increased but are still at moderate levels (lower than 1 kg/capita per year). However, the moderate values are due to their large populations, and the actual level of use is high31,32 (e.g. in 2007, China and India used 626 000 and 302 000 tons, respectively; data not shown), which could potentially expose many people to asbestos. Recently we estimated the number of mesothelioma cases in countries where the disease is unreported by assuming that the cumulative number of mesothelioma cases is related to the cumulative asbestos use. These estimates suggested that China and India have already ‘missed’ 5100 and 2200 cases, respectively.27 Although high per capita use will likely lead to high disease rates, moderate per capita use in populous countries should not be underestimated.
The asbestos file of the USGS compiles information on the production (mining), trade and use of asbestos by country and has been referenced widely to assess asbestos-related situations in the world. It is possible, however, that the USGS data on asbestos use are not as complete for less-developed countries, especially in the earlier years. According to the USGS, Vietnam and Mongolia first used asbestos in 1998. In a recent scientific meeting to promote international cooperation for the elimination of ARD in Asia, however, national representatives reported contradicting information: Vietnam established its first asbestos-cement factory in the mid 1960s33 in the province of Dong Nai, and Mongolia started to import asbestos in the early 1960s for application in power plants.34 These reports are yet to be documented in the scientific literature, but they suggest that some historical information is not well documented.
Political actions by countries as countermeasures for asbestos use were assessed in terms of the ratification status of the ILO Asbestos Convention23 and adoption of asbestos bans.24 Although the ratification status of asbestos bans in Asia is similar to the rest of the world, the ratification status is lower. Interestingly, the three Asian countries taking both political actions (i.e. Cyprus, Japan and Korea) have recently experienced the burden of ARD. Previously, we reported on early indications suggesting that the adoption of bans may contribute to a subsequent reduction in mesothelioma mortality at national levels.12 A practical recommendation to Asian countries is to not only ban asbestos use as soon as possible, but also to minimize exposure to asbestos and to ratify the ILO Asbestos Convention.
The strength of the present study was that it was a comparative assessment of a wide range of countries, based on data in public databases, which has been widely referenced and complemented by scientific literature. In addition, the present study applied quantitative indicators to the data (e.g. AAMR and per capita use). Our study had several limitations, however, including the representation and comparability of the original extracted data. The use of asbestos may not have been fully grasped for each country and ARD are known to be generally rare and difficult to diagnose. The most serious bias could have been the data validity in countries with limited experience in diagnosing ARD and underreporting is probably the most dominant problem.27 Hence, our findings should be viewed as an underrepresentation of the actual situation.
In conclusion, our analyses of available data in public databases and the literature revealed a paucity of information on ARD in Asia. This finding is likely related to the fact that asbestos use was not high until around 1970, but it is also compounded by the poor political will to improve national situations and the lack of resources to diagnose ARD. Most importantly, asbestos use in Asia has increased drastically since 1970 and has reached formidable levels in terms of per capita use and absolute volumes. A surge of ARD in Asia should be anticipated in the coming decades. Asian countries should not only cease asbestos use but also prepare themselves for an impending epidemic of ARD.
This work was supported in part by the JSPS (Japan Society for the Promotion of Sciences), the AA (Asia Africa) Science Platform Program, and a Project for the Development of a Toolkit for the Elimination of Asbestos-Related Diseases, commissioned by the Rotterdam Convention Secretariat.