Is China’s Pollution Poisoning Its Children?

The coal-burning power station that loomed over Tongliang was a Vesuvius of PAHs , and its closure in 2004 changed environmental conditions in the city virtually overnight. That makes Tongliang something very rare in the world of epidemiology: a feasible laboratory for measuring the before-and-after health impacts of air pollutants. The city is still far from pristine, but passing cars no longer kick up clouds of black soot from the street and families can hang their wash outside to dry for more than a few minutes without their white shirts turning gray. The air-pollution monitors that the Columbia team installed around Tongliang confirm the improvements: airborne concentrations of one of the most important PAHs, benzo(a)pyrene, or BaP, fell by about 30 percent between 2002 and 2005. Other PAHs declined even more.

The changes that interest Perera the most, however, are taking place in the bodies of the city’s youngest residents.
Since 2002 she and Tang, along with Tin-yu Li of Chongqing Children’s Hospital, have been studying 450 children who live within two kilometers of the plant site by testing their DNA and measuring their physical and mental development starting at birth. The researchers’ preliminary analysis shows that children born in 2002, when the power plant was still operating, have smaller heads and score worse on developmental tests than those born in 2005, a year after the plant closed. There are also differences at the molecular level: concentrations of BaP-DNA adducts were about 40 percent higher in the white blood cells of newborn babies in Tongliang in 2002 than in those of children born three years later.

Perhaps most meaningful of all, in the children born in 2002, measured concentrations of BaP-DNA adducts closely correlated with head circumference and developmental test scores. In other words, the more damage a child’s DNA suffered in the womb, the more likely he or she was to be born with a smaller head and to score worse on tests of motor skills and overall development as a toddler. The correlations were weaker among babies born in 2005, suggesting that air pollution becomes less of a risk as overall levels drop. Children born in 2005 will probably be slightly less likely to get cancer, according to Perera, whose previous work suggests that adduct counts correlate with cancer risk.

Scientific American