Published July 19, 2011
Pregnant women who are exposed to coal smoke and pesticides are up to four times more likely to have babies with serious birth defects than women not exposed to these chemicals, a Chinese study has found.
The researchers studied 80 newborn babies and aborted fetuses with brain and spinal cord defects and found that their mothers' placentas had significantly higher amounts of chemicals compared to placentas of babies without such birth defects.
These defects have long been linked to folic acid deficiency, maternal obesity and diabetes. While environmental pollution has long been suspected as a culprit, there has been very little direct evidence showing the link.
In the Chinese study, researchers detected high levels of polycyclic aromatic hydrocarbons (PAHs) that come from inhaling smoke from burning coal, and synthetic pesticides such as DDT, hexachlorocyclohexane (HCH) and endosulfan in the placentas of women who had babies with such birth defects.
"In addition to nutrients and oxygen ... pollutants can readily cross the preplacental structures and potentially impact embryonic development," lead author Tong Zhu at the State Key Joint Laboratory for Environmental Simulation and Pollution Control in Beijing University told Reuters in an e-mail.
The study's findings were published on Tuesday in the Proceedings of the National Academy of Sciences.
Common Birth Defects
Brain and spinal cord birth defects, called neural tube defects (NTDs), are common, occurring to 1 in every 1,000 live births in the United States. One of its most common forms is when the spinal column does not close completely in the first month of pregnancy, resulting in nerve damage and paralysis of the legs.
Another common NTD is when the head end of the neural tube fails to close, leaving the brain undeveloped. Such babies tend to end up stillborn or die shortly after birth.
Zhu and colleagues recruited pregnant women in four rural counties in northern Shanxi province where NTDs occur in 14 out of every 1,000 babies - far higher than the national average.
They analyzed the placentas of 80 babies or aborted fetuses with NTDs and compared them to placentas of 50 babies without such defects.
Women whose placentas had higher than average levels of the PAH chemicals from burning coal were 4.5 times more likely to have babies with defects, while those with more than average levels of pesticides were around 3 times more likely to have babies with defects, the researchers found
Zhu urged women to avoid coal smoke and to use cleaner fuels for heating and cooking, as well as to avoid inhaling second hand smoke.