This story is a supplement to the feature "Is China's Pollution
Poisoning Its Children?" which was printed in the August 2008
issue of Scientific American. Tongliang children born in 2002,
when the local coal-burning power plant was still open, scored
worse on tests of motor and social skills than did their
counterparts born in 2005, one year after the plant stopped
operating. Researchers classified children as developmentally
delayed if they scored below 85 on a standard assessment known
as the Gesell test. The children born in 2002 had higher
concentrations in their white blood cells of PAH-DNA adducts—DNA
alterations caused by exposures to harmful chemicals, called
polycyclic aromatic hydrocarbons (PAHs) in polluted air. Among
children born in 2002, adduct frequency closely correlated with
developmental delay.