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					Pregnant 
					women who live in smog-filled areas may be twice as likely 
					to have children with autism, a new study suggests. "The 
					study does not prove that pollution increases risk for 
					autism. It found an association," said the  lead author. "It 
					adds to the weight of the evidence that there may be 
					something in air pollution that increases risk for autism." 
					Researchers compared exposure to air pollution among 325 
					women who had a child with autism and 22,000 women who did 
					not. The women were participants in the Nurses' Health Study 
					II. Pollutants measured included diesel particulate matter, 
					lead, manganese, mercury, methylene chloride, and a combined 
					measure of metal exposure. Twenty percent to 60 percent of 
					the women lived in areas considered highly polluted. And the 
					study showed that: those women who lived in the 20 percent 
					of locations that had the highest levels of diesel 
					particulates or mercury in the air were twice as likely to 
					have a child with autism, compared to those who lived in the 
					20 percent of areas with the lowest levels of these 
					pollutants. In addition, those who lived in the 20 percent 
					of locations with the highest levels of lead, manganese, 
					methylene chloride, and combined metal exposure were about 
					50 percent more likely to have a child with autism than 
					those who lived in the 20 percent of areas with the lowest 
					concentrations. The findings held even after the researchers 
					took into account other factors known to affect autism risk, 
					such as income, education and smoking during pregnancy. 
					Overall, the association was stronger for boys than it was 
					for girls, but the number of girls included in the new study 
					was too low to draw any firm conclusions. Exactly how, or 
					even if, air pollution affects the developing brain is 
					murky. "By definition, pollution is stuff that is not good 
					for us," the author said. Still, the overall increase in 
					autism risk that may be attributed to pollution is low. 
					"Let's say a woman's risk for having a child with autism is 
					one in 100, women who live in the most polluted cities have 
					a risk that is about one in 50, which means that 49 children 
					would not have autism," researcher added.  |