Neural-Tube Birth Defects Tied to Organic Pollutants
Neural tube defects, in which the spinal cord, the brain or their coverings fail to develop completely, arise very early in pregnancy and affect more than 320,000 infants worldwide every year. They can lead not just to spina bifida, in which the spinal covering does not close completely, but also to severe cranial abnormalities such as anencephaly, which often leads to stillbirth, and other conditions.
Previous studies have linked certain pollutants, in particular polycyclic aromatic hydrocarbons (PAHs), from sources such as indoor coal stoves, smoking and vehicle exhausts, to neural tube defects. But most of the evidence has been anecdotal, based on mothers saying they had been exposed to certain pollutants, or has relied on tests of the mother’s blood alone.
Now an interdisciplinary team of researchers in China has shown the risk of a newborn or fetus having a neural tube defect is much higher when certain organic pollutants are found in the placenta, which shows what is actually reaching the fetus, rather than just what is circulating in the mother’s blood stream.
“We only see the high levels of pollutants in the placenta, but we don’t know if it’s a true causal relationship,” cautions reproductive health scientist Aiguo Ren of the Institute of Reproductive and Child Health at Peking University in Beijing, one of the authors of the new study.