8 July 2013. Exposure to brain drainers is unevenly distributed. The brunt of the burden is carried by developing countries. Pesticides are used to a much greater extent in tropical countries, where safety measures are often lacking. Also, pesticides that have been banned elsewhere are still widely used in developing countries (and often imported from industrialized countries where their use is illegal).
Recent studies in Brazil and Nepal demonstrate that many farmers in developing countries have incomplete knowledge on health risks from the pesticides they use. Personal protective equipment is infrequently used, and inhibition of the serum enzyme, cholinesterase, suggests toxic exposure to organophosphate pesticides. But the greatest risk is probably carried by the farmers’ households. Even though pesticides are not stored at home, the chemicals can be found in house dust, and household members, including newborn children, show elevated pesticide concentrations in blood and urine.
Other brain drainers of serious concern in developing countries include metals, such as lead, from lead mining, battery manufacture, leaded gasoline, electronic waste, traditional medicines, and other sources (see “Only one chance”, pp. 46 and 129). The impacts on brain development by these exposures are probably enormous, but how large are they actually?
This question has now been tackled by New York University researchers. They used existing, though scattered, data on blood-lead concentrations to develop a model that estimated the distribution of lead exposures in children in low­ and middle­ income countries. They then calculated the lead-related IQ loss. A loss of 1 IQ point was assumed to cause a decrease in lifetime income of 2%. By proper adjustment for discounting, gross domestic product (GDP), and purchasing power, the researchers estimated a total annual loss of almost 1 trillion dollars. The greatest relative loss occurs in Africa ($135 billion or 4% of GDP), while the greater losses in South America and Asia correspond only to about 2% of GDP. In the US and Europe, annual losses are about $50 billion. All told, the IQ drain due to lead costs about 1.2% of world GDP – almost 90% occurs in developing countries.
These results relate only to lead, and economists may argue about details of the calculations.Thus, the results are far from precise, but provide a scary order of magnitude. Worse, pesticides. solvents, and other brain drainers also cause serious losses in GDP, although data are not available to calculate just how much. Overall, average IQs are known to be lower in developing countries, and there is a clear association between national average IQ and the GDP. Thus, countries with higher IQs are more productive and more wealthy (see “Only one chance”, p. 113). The enormous economic losses associated with lead exposure suggest that prevention of brain drain would be an effective and necessary strategy to support developing countries.