Globally, each year, an estimated 125 million people are occupationally exposed to asbestos, and 90,000 die from asbestos diseases (WHO 2006a). Around the time of peak use in the mid-1970s, approximately 25 countries produced asbestos and 85 countries manufactured asbestos products (Virta 2005). In 1983, Iceland became the first country to ban asbestos, reflecting increasing recognition, predominantly in Western countries, of health risks associated with asbestos exposure. Subsequently, 40 or more countries have adopted bans (WHO 2006a).

Among the asbestos diseases, mesothelioma is the most sensitive and specific indicator of the disease burden in the population (Weill et al. 2004). The annual incidence of mesothelioma has been estimated at 10,000 cases in Western Europe, North America, Japan, and Australia combined (Anonymous 1997). Peto et al. (1995, 1999) predicted a dramatic increase in future mesothelioma deaths in the United Kingdom and Europe. Several statistical projections have been made since then, suggesting that deaths from mesothelioma will increase in many countries.

We assessed mortality trends over the most recent 10-year window, using the earliest opportunity to analyze the disease under the standard code of ICD-10. However, the study period was inadequate to depict trends in many countries. National data recorded only under ICD-9 had to be precluded (e.g., Italy). For the countries shifting from ICD-9 to ICD-10 during the study period, we limited our analyses to the period when data were recorded under ICD-10.

Further, data may lack comparability, especially because mesothelioma is rare and difficult to diagnose. A major concern is that increasing trends recorded in countries with low mortality levels could be explained by improved disease recognition (Peto et al. 1995; Weill et al. 2004), and such secular trends in diagnosis would be statistically indistinguishable from real increases (Peto et al. 1995). Our study revealed increasing mortality trends in the group that recorded above-median values for the period MR (group 1) than the group that recorded below-median values for the period MR (group 2). Such bias is likely to be less serious in group 1 than group 2. Thus, although increases in disease recognition are probable, this factor alone does not explain the increasing trends. The proportionality with which recent mortality trends were related to historical trends of asbestos use offers a more compelling explanation.

Pleural mesothelioma is the predominant type of mesothelioma and is strongly related to asbestos exposure. However, in certain countries, most mesothelioma was coded into the subcategory of unspecified mesothelioma (C45.9) instead of the subcategory of pleural mesothelioma (C45.0): the ratio of C45.0 to C45.0 + C45.9 ranged from 0.08 (Israel), 0.11 (United States), and 0.12 (Canada) to 0.94 (New Zealand) and 0.98 (Finland), with a median of 0.63. We therefore created a composite category of C45.0 and C45.9 to ensure comparability, which we deemed more reasonable than the alternative choices of analyzing only C45.0 or mixing C45.0 with other subcategories—for example, peritoneal (C45.1) or pericardial (C45.2) or other sites (C45.7).

Our findings on mortality trends are comparable with trends reported earlier for individual countries, including the Netherlands (Segura et al. 2003), Sweden (Burdorf et al. 2005), Finland (Karjalainen et al. 1997), and Denmark (Kjaergaard and Andersson 2000), as well as overall Europe (Montanaro et al. 2003). However, methods and indices employed to evaluate trends are unique to each study, and comparisons cannot exceed the general trend characteristics. For the United States, we recorded equivocal trends (i.e., APC = 0.8%). Similarly, Price (1997) first observed that the annual growth rate during 1973–1992 was declining, and Price and Ware (2004) reported “no substantive changes in time pattern of mesothelioma incidence since 1992.” Furthermore, surveillance information in United States does not show an apparent trend from 1999 to 2002 (National Institute for Occupational Safety and Health 2005).

Regarding historical trends in asbestos use, we identified several distinctive patterns: a) a very early (1950) and very high (≥ 4.0 kg per capita/year) peak followed by a progressive decline (in the United States); b) a mid-term (1960s–1980s) very high peak, followed by an abrupt decline (Australia and several Northern and Western European countries); and c) a late (≥ 1980) and relatively moderate peak followed by a moderate decline (Hungary and Japan).

In the United States, a “bubble” in asbestos use occurred in the mid-20th century because of early manufacturing research, industrial demand, and ready supply from Canada (Virta 2006). However, the United States was also the first to experience the burst of the bubble due to growing health concerns and liability issues (Virta 2006). In 1989, the U.S. Environmental Protection Agency (EPA) banned most asbestos-containing products, but this regulation was overturned by the U.S. Court of Appeals in 1991 (U.S. EPA 1989). Nevertheless, use fell to 4,600 tons in 2003 (0.7% of peak use). In many other countries, increasing use of asbestos paralleled the growth curves of industrialization.

Generally, countries recording early and high levels of asbestos use displayed peaks by 1980 followed by downward trends. The turning points preceded the earliest bans and are thus not direct outcomes of bans. Rather, paths leading to bans likely entailed regulatory restrictions and economic incentives and disincentives, which furthered reduction of use. Virta (2005, 2006) attributed maturation of the asbestos market superimposed on health issues as the main reason for the decline in use since 1980. Several relevant events with international impact coincided with this period. The International Agency for Research on Cancer (IARC), after acknowledging the carcinogenicity of asbestos in 1973 (IARC 1973), classified asbestos as a human carcinogen in 1977 (IARC 1977). The ILO added lung cancer and mesothelioma caused by asbestos to its list of occupational diseases in 1980 (ILO 1980) and adopted the Asbestos Convention in 1986 (ILO 1986). It was also around this period that the landmark studies by Selikoff and colleagues (Nicholson et al. 1982; Selikoff et al. 1984a, 1984b) gained wide recognition.

The adoption of bans by Northern European countries in the 1980s set a precedent for other countries, but the particular restrictions imposed by a “ban” vary by country, and the rates at which the absolute zero use levels were reached also vary. Collectively, countries adopting bans reduced use about twice as fast as those with lesser interventions. Notably, the countries of Eastern and Southern Europe (grouped here as “other” countries in Table 2) have continued to use asbestos, approaching high levels even after the turn of the century. The recent per capita use for the “other” Asian countries is low but shows little sign of decreasing. This is largely attributable to sustained use in China and India. Hence, our findings reinforce the widely held concern that the center of asbestos use is shifting to industrializing countries (Kazan-Allen 2005; LaDou 2004; Takahashi and Karjalainen 2003). Moreover, if the ecologic relationship reported here holds true for the future, corresponding risks should be anticipated in these countries.

Regression analyses showed the strongest relationship between recent APC in mortality from pleural mesothelioma and change in asbestos use during 1970–1985 (adjusted R² = 0.47, p < 0.0001). The same analyses incorporating countries with six or more data points produced similar results (data not shown). The strong relationship is largely attributable to countries recording recent mortality trends in the same direction as historical use trends (lower-left and upper-right quadrants in Figure 2). The positive correlations found for change indicators of a number of periods in the present study reinforce the notion that per capita asbestos use is related to subsequent mortality level at the national level, as we reported earlier using absolute-level indicators (Lin et al. 2007). However, the time difference (i.e., latency) for the best predictive model was only 22.5 years (from mid-1977 to 2000), and thus the observed relationship may have reflected only early effects. In this connection, recent mortality trends of the eight early-ban countries are noteworthy: Seven countries recorded had equivocal MR trends, and only Germany had an increase in MR trend (Table 1). Germany actually recorded a historical use peak in 1980, trailing other early-ban countries by 5–10 years (detailed data not shown) and presumably delaying favorable changes in mortality trend. Continuing use of asbestos results in the accumulation of asbestos in the environment, thus creating possibilities for ongoing exposure due to maintenance, repair, and demolition during the entire life span of asbestos products. Given the long latency time, the mortality data available did not allow us to analyze the full consequences of such effects after the new use in longer term. Nevertheless, we observed significant (albeit weaker) relationships for changes in use during other close periods with longer latencies [e.g., 1950–1985 (latency 32.5 years) and 1950–1990 (30 years)].

In this study, we took advantage of the earliest opportunity to analyze mortality trends in a range of countries. Limitations included our dependence on a crude indicator of exposure (i.e., asbestos use per capita for sparse years with limited data), “bans” entailing varying restrictions on use that could not be measured, and no distinctions available between asbestos fiber types. Mortality data were limited to 31 countries, with developing countries likely lacking well-developed surveillance systems to assure quality of data. Moreover, the observed relationships are ecologic at the national level only, so all findings should be cautiously interpreted.