环境污染会导致婴儿先天畸形

Pesticides and pollutants are related to a 450 percent increase in the risk of spina bifida and anencephaly（先天无脑畸形） in rural China, according to scientists at The University of Texas at Austin and Peking University. Two of the pesticides found in high concentrations in the placentas of affected newborns and stillborn fetuses were endosulfan（硫丹） and lindane. Endosulfan is only now being phased out in the United States for treatment of cotton, potatoes, tomatoes and apples. Lindane was only recently banned in the United States for treatment of barley, corn, oats, rye, sorghum and wheat seeds.

Strong associations were also found between spina bifida and anencephaly and high concentrations of polycyclic aromatic hydrocarbons (PAHs), which are byproducts of burning fossil fuels such as oil and coal. Spina bifida is a defect in which the backbone and spinal canal do not close before birth. Anencephaly is the absence of a large part of the brain and skull.

"Our advanced industrialized societies have unleashed upon us a lot of pollutants," says Richard Finnell, professor of nutritional sciences and director of genomic research at the Dell Children's Medical Center of Central Texas. "We've suspected for a while that some of these pollutants are related to an increase in birth defects, but we haven't always had the evidence to show it. Here we quite clearly showed that the concentration of compounds from pesticides and coal-burning are much higher in the placentas of cases with neural tube defects than in controls."

The study, which was published in August in the Proceedings of the National Academy of Sciences, is the result of a more than decade-long collaboration between Finnell and a team of researchers in Shanxi, a province in northern China.

Finnell sought collaborators in China because the prevalence（流行，普遍） of neural tube defects is much greater there than it is in the United States. Also, because of its population policies, China is good at tracking births.

"It's an extraordinary natural experiment," says Finnell, who was recently recruited to the university to help anchor the Dell Pediatric Research Institute. "It would be much harder to do this study in the United States, where neural tube defects are more rare. It's also an opportunity to assist the Chinese government in their efforts to lower their birth defect rates."