The global historical pattern of national asbestos use vis-à-vis per capita GDP is consistent with the so-called environmental Kuznets curve (EKC). The trajectories of individual high- income countries are remarkably similar despite different time courses. A common ceiling or inflection point in asbestos use is observed at an income level of approximately 10,000–15,000 GKD, in line with the EKC theory.
The EKC theory postulates an inverted U-shaped relationship between environmental pollutant levels and economic growth (Andreoni and Levinson 2001
; Grossman and Krueger 1995
; World Bank 1992
): examples include SO2
, and lead (in air) and sewage (in water). Unlike the situation with by-products of or emissions from industrial processes, which may be compounded by the lack of comparable definitions and/or data, reliable historical statistics are available for asbestos, a longstanding industrial commodity. By applying a per capita indicator, we assessed asbestos use trends over 8 decades in most countries of the world.
The figures show no time dimension, but countries in fact move along a common time axis, experiencing simultaneous economic development and, up to a point, asbestos use. To show the bivariate relationship over time, Motion Chart, a web-based software application designed for tracking several data points to see changes over time (Google 2009
), was applied to the data set [see Supplemental Material, Figure 3 (doi:10.1289/ehp.0901196.S1). A clear log-linear to log-curvilinear relationship between per-capita GDP and asbestos use is observed during earlier years. This relationship begins to collapse when countries consecutively peak out use at the inflection point.
The wax-and-wane use pattern exhibited by high-income countries is probably associated with acceptance, over time, of the fact that asbestos is an established carcinogen. The final step to abandon asbestos use appears to have become easier with the increasing availability of safer and commercially viable substitutes. In contrast, middle- and low-income countries continue or even increase use with economic growth at the respective stages of development. It is plausible to assume that countries with a long history of high asbestos use (and thus a high accumulation of asbestos in the society) have already seen the disease burden taking its toll, whereas those with a short history have not or have only started to see diseases reflecting recent use.
The positive correlation between asbestos use and GDP observed prior to the inflection point suggests interdependence between the two factors. During times of soaring infrastructure demands, intense forces for use of inexpensive construction materials are in play. The subsequent downturn in use occurs despite continued economic growth. Moreover, high-income countries did not sustain use and eventually shifted to abandonment. Even Canada, a major producer and exporter of asbestos, appears to follow the path common to high-income countries, although major fluctuations are evident. Societal responses to hazards of asbestos (ultimately bans for all types of asbestos including chrysotile) have been embraced by high-income countries but notably less so by lower-income countries.
Inflection points in consumption at approximately 10,000–15,000 GKD were experienced by most high-income countries/entities with a few exceptions (e.g., United Arab Emirates and Hong Kong) [see Supplemental Material, Figure 2 (doi:10.1289/ehp.0901196.S1). This point was also observed for Venezuela, a middle-income country approaching a higher-income level. Since the dissolve of the USSR in 1991, Russia and Kazakhstan have recorded asbestos use at 3.53 and 7.82 kg/capita/year, respectively, which contributed to the overall high group mean of the middle-income countries. The collective path of the middle-income group may be tapering slightly, indicating early signs of deviation from the trailing path. This could arise because of a perceived “benefit [arising] from the science and engineering lessons of the early movers” (Levinson 2008
). However, the ultimate responses to current knowledge and the experience of high-income countries is uncertain.
As our group means were weighted by national population sizes, group patterns will most strongly reflect trends in populous countries (e.g., China and India). These countries have moderate per-capita use levels because of their large populations, and they exhibit steady trends. However, even a moderate level of per capita use in such countries indicates a high total use (in 2003, China and India consumed 492,000, and 192,000 tons, respectively), which can potentially lead to the exposure of many people. The application of income per capita assessed in GKD reflected only one aspect of economic development, but nevertheless allowed a comparison of countries on a global historical scale.