|Is China's Pollution Poisoning Its Children? |
By Dan Fagin
Epidemiologists find molecular clues to air pollution's impact on youngsters
Preliminary results from a study conducted in Tongliang, China, reveal that
children exposed to highly polluted air while in the womb had more changes in
their DNA—and a higher risk of developmental problems—than did those whose
mothers breathed cleaner air during pregnancy.
A central goal of molecular epidemiology is to tie environmental factors to
genetic changes that contribute to disease. \
Some biologists have questioned the approach, because few candidate molecular
markers of susceptibility, exposure or early disease have yet been proved to
foretell future illness.
Now researchers may have found the best test case yet for environmental
molecular epidemiology: a city in China whose coal-fired power plant was shut
down in 2004.
Preliminary analysis shows that children born in 2002, when the plant was
still operating, have smaller heads and lower scores on developmental tests
than those born a year after the plant closed. They also have correspondingly
higher levels of pollution-related genetic abnormalities.
A few heaping piles of scrap metal and a rusty coal shed are all that is left of
the power plant that until recently squatted like an immense, smoke-belching
dragon in the middle of Tongliang, a gray city of 100,000 in south-central
China. As we walk toward the shed, a Belgian Shepherd begins barking furiously,
jerking its iron chain and baring sharp teeth. A brown-eyed face peeks out from
the open doorway—it belongs to a girl in a stained shirt, holding a tabby cat
that jumps away to hide under a slab of concrete as we approach. The girl is no
more than six or seven years old and appears to be living in the shed with her
father, who watches us warily from within.
The delegation of local officials who are taking us on a tour of the site are
embarrassed; they want to hustle us along to a nearby office to show us an
elaborate scale model of an extravagant (by Tongliang standards) 900-unit
housing development planned for the property. But Frederica Perera is intrigued.
She strides toward the girl and gives a friendly “ni hao” and a smile. The girl
smiles back before retreating back into the shadows with her father.
Children, after all, are why Perera is here. She is looking for connections
between air pollution and disease, especially in children who were exposed to
pollutants in the womb. The director of Columbia University’s Center for
Children’s Environmental Health, Perera helped to pioneer the field of molecular
epidemiology, which applies the tools of molecular analysis to identify genetic
and environmental factors that contribute to disease. She and other molecular
epidemiologists who focus on environmental links to illness increasingly do much
of their work in the developing world, where pollution is so ubiquitous that its
complex connections to health can be calibrated even in small study populations.
But their conclusions should also apply in places such as the U.S., Europe and
Japan, where environmental exposures are subtler and their effects more
difficult to measure in small-scale studies.