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.

The findings in China confirm earlier research indicating that PAH-DNA adducts can serve as a fingerprint of exposure to pollution. These adducts may also change the functions of genes that promote or suppress disease, although exactly how they might lead to developmental decrements in fetuses exposed to them is unclear. Several mechanisms have been proposed, however.