Worth reading in full to get the results and background.
Is China's Pollution Poisoning Its Children? [Scientific American]
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.
Wherever they work, what distinguishes the approach of molecular epidemiologists is their search for biological indicators that closely correlate with toxic exposures and illness. Often these markers take the form of chemicals bound to DNA or of changes in gene structure or activity that match up with particular types of contaminants and disease. Now that DNA microarrays and other screening technologies are making it much easier to measure many of those biomarkers, routine use of such tools could, at least theoretically, save lives by identifying populations at risk from specific pollutants.
The science is still controversial, however, because relatively few candidate molecular biomarkers of susceptibility, exposure or early disease have been fully validated—that is, proved to herald future illness—and because it is very difficult to factor out confounding variables such as diet and genetic predisposition that may be at least as important as exposure to pollutants in causing various ailments. What has proved even more difficult is getting a handle on how those disparate risks may be interacting to affect health.