Results are shown by continent.
Figures 1 and 2 show results for Europe, for which there have been more studies in different countries of blood level levels over time than for any other continent. Studies from several countries – Germany, Sweden, and Spain – show blood lead concentrations of less than 2 µg/dL. All of the European studies show decreased blood lead concentrations over time. Figure 2 shows that in the majority of locations, blood lead concentrations fell along with gasoline lead concentrations. However, in both Istanbul and East Germany, and to some extent Venice and Zagreb, blood lead levels fell without a reduction in gasoline lead. This may indicate reduction in other sources of exposure, or improve measurement techniques.
Even though there are numerous European studies, there are countries for which there are no data on how blood lead concentrations have changed over time. There are no studies from Russia, Ukraine, Romania, Netherlands, Czech Republic, and others. Russia is a major lead producer, but nonetheless took early action to eliminate lead from gasoline in major cities [27].
Figures 3 and 4 show data from North America. The data for the United States are the most extensive in North America, and show that US blood lead concentrations have fallen below 1 ug/dL as of 2011. Canadian data from Ontario and specifically Toronto are less extensive and somewhat higher than the results from the US overall. Studies from Mexico show higher blood lead levels, decreasing over time and decreasing as gasoline lead concentrations decreased.
Figures 5 and 6 show data from South America. There are no studies in our data set from Central America. The South American studies are from Venezuela, Chile, Uruguay, Argentina and Peru. There are no studies on blood lead concentrations over time from Brazil, Columbia, Ecuador and others. The lowest population blood lead concentrations reported in these studies is 2.6 ug/dL, in Cordoba, Argentina from 2010. The trajectories shown across the studies suggest that current blood lead levels in Lima, Santiago, and Montevideo may now be lower.
Figures 7 and 8 show the data for Asia. Figure 8 shows that blood lead concentrations have decreased over time in all of the Asian data sets. Figure 7 shows that in most of the countries, decreasing blood lead concentration is associated with decreasing concentrations of lead in gasoline. For Mumbai, India, there was substantial decrease in the concentration of lead in gasoline while blood lead levels remained roughly constant. However, between 1985 and 1995, while the concentration of lead in gasoline decreased by approximately a factor of two, the amount of gasoline consumed rose by approximately a factor of 2. All of the data sets from China show falling blood lead concentrations with gasoline lead levels already at low levels. While data on use of lead in gasoline in China are sparse, there is no indication of heavy use of lead in gasoline. The decreasing blood lead concentrations in China may reflect decreases in other sources of lead exposure. The lowest levels from these studies is 1.4 ug/dL, from Japan in 2011.
Figures 9 and 10 shows result for Africa, for South Africa, Nigeria, and the Democratic Republic of Congo. Although lead was phased out of gasoline in many African countries by 2006, there are ongoing exposures from other sources [28, 29]. The data shown in Figs. 9 and 10 show consistent slopes, with decreases corresponding to reduced use of lead in gasoline and over time. All of the African studies show relatively lower blood lead concentrations for the gasoline lead concentrations, compared to the results from South America, North American and Europe, while similar to the results from Asia. These may indicate comparatively low consumption of gasoline in the African cities studied, compared to the studies from North and South America and Europe. Further studies of lead exposure in more locations in Africa would be welcome to further examine population lead exposures and trends.
Figures 11 and 12 show data from Oceania. This region includes Australia, New Zealand, Melanesia, Micronesia, and Polynesia. There has only been a one published study of blood lead concentration trends in a general population: the study shown from Christchurch New Zealand. Australia has been one of the world’s largest producers of lead since the 1800’s, and has the world’s largest lead reserves. Yet there has been no study of population exposure trends. The Christchurch New Zealand study shows a significant decrease in blood lead concentrations from 1978 to 1984, a time during which the gasoline lead concentrations did not change. This may indicate reductions in other sources of lead exposure, or improvements in laboratory measurement techniques. After 1984 the relative values of blood lead versus gasoline lead are similar to those in Europe and in North and South America.