The Agenda

Thorfinn on Garett Jones and the Importance of Brain Health

One of the most important global public policy issues is, in my view, infant brain health. At Brown Pundits, a blog devoted to South Asian issues understood broadly, Thorfinn, who also blogs at GNXP, highlights an intriguing passage from Garett Jones’s new paper on “National IQ and National Productivity”:


A study of excessive fluoride in Indian drinking water found a 13 IQ point-difference between children “residing in two [separate] village areas of India with similar educational and socioeconomic conditions” (Trivedi et al. 2007, 178). If even half of this relationship is genuinely causal, and if intelligence has some of the technological and political spillover effects discussed below, then public health matters are of first-order concern for economic development.

Arsenic and fluoride exposures are also associated with low IQ in the People’s Republic of China’s (PRC) Shanxi province (Wang et al. 2007, 664), even when comparing “groups [who] lived in rural areas with similar geographic and cultural conditions and a comparable level of socioeconomic development.” High arsenic exposure was associated with a 10-point IQ gap, and high fluoride exposure with a 4-point gap. In both cases, the “normal” group had an IQ of 105, 5 points above the US mean.

In the Visayas region of the Philippines, Solon et al. (2008) found evidence that lead levels reduced the IQ of children.  In their study, one microgram of lead per liter of blood was associated with a 2.5 point reduction in the verbal IQ of older children, and a 3.3 point reduction in the IQ of young children.  In their sample of children, the levels of lead in the blood averaged 7.1 micrograms per liter, so lead exposure could be costing the average child in this sample 15 IQ points even under conservative estimates.

In an experimental nutritional study in Pune City, India, 10 weeks of zinc supplementation caused a 15–25 percent increase in the number of correct answers on the Raven’s Progressive Matrices (Tupe and Chiplonkar 2009).

Given the large spillover effects of relatively small differences in collective IQ …

[Jones] suggests that while one more IQ point might indicate a higher individual wage of 1%; an increase of 1 IQ point for the population mean implies a higher mean income of 3-4%.

threats to infant brain health represent a profound problem. 


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