In the study, researchers tracked and compared the development of two groups of children born in Tongliang, a city in China's Chongqing Municipality - one in utero while a coal-fired power plant was operating in the city and one in utero after the Chinese government had closed the plant.
The researchers discovered that in the first group of children, prenatal exposure to coal-burning emissions was linked with significantly lower average developmental scores and reduced motor development at age two.
On the other hand, in the second unexposed group, these adverse effects were not visible anymore; and the frequency of delayed motor developmental was significantly reduced.
"This study provides direct evidence that governmental action to eliminate polluting coal-burning sources benefits children's neurodevelopment. These findings have major implications for environmental health and energy policy as they demonstrate that reduction in dependence on coal for energy can have a measurable positive impact on children's development and health - in China and elsewhere," said Frederica Perera, DrPH, professor of Environmental Health Sciences at the Mailman School of Public Health, director of the Columbia Center for Children's Environmental Health, and lead author of the study.
For the study, the investigators followed two successive cohorts of Chinese newborns through age two in Tongliang. The first cohort involved 107 women whose children were born in 2002, prior to the plant closing. The second involved 110 women whose children were born in 2005, when the coal plant was no longer in operation.
"This is a unique environmental intervention study using molecular techniques to demonstrate the relationship between a cleaner environment and healthier children," added Deliang Tang, MD, DrPh, associate professor of clinical Environmental Health Sciences at the Mailman School, director of the Tongliang Project, and co-author of the study.
The researchers measured prenatal exposure to plant emissions by a biomarker of polycyclic aromatic hydrocarbon (PAH) exposure in umbilical cord blood. They then controlled for exposures to other pollutants, such as tobacco smoke and lead, which might have contributed to neurodevelopment problems.
It was observed that children in the first cohort had varying exposure prenatally to PAHs emitted by the coal-fired power plant. This exposure was recorded by monitoring the levels of PAHs in air during the mothers' pregnancies and in measuring a marker of PAH exposure in cord blood-- specifically the levels of PAHs bound to DNA, known as "PAH-DNA adducts".
Significant associations between the marker of exposure in cord blood and delayed motor and average development at age two was found among these children. The second group of children, who were conceived after the closure of the plant, had significantly lower levels of the marker in cord blood and their incidence of delayed motor development was one-third that of the first cohort.
In earlier research, it was shown that exposure to air pollutants are linked with an increase in risk for developmental delays among children living in New York City and the new findings contribute to a further understanding of how air pollution impacts child health.
The study findings are published in the July 14th Environmental Health Perspectives.