Fri, Dec 19, 2014 - Page 7 News List

Air pollution in pregnancy might cause autism: study

‘CAUSAL EFFECT’:Researchers said there was likely an inflammatory or immune system response to pollution that reaches the fetus and influences autism development

Bloomberg

Women who are exposed to high levels of air pollution during their third trimester of pregnancy might be twice as likely to have an autistic child, a study found.

Researchers from the Harvard School of Public Health found the risk of autism rises in parallel with exposure to fine particulate matter during pregnancy, with the biggest effect occurring in the final months of gestation. The results appear in yesterday’s edition of Environmental Health Perspectives.

The findings add to other research suggesting that the environment plays a role in the development of autism, a developmental disorder marked by repetitive behaviors, and trouble communicating and socializing.

The study, which started in 1989 and involved more than 100,000 nurses from across the US, should help researchers home in on the causes of autism and potential ways to prevent it, the study’s senior author Marc Weisskopf said.

“One of the unique aspects of the study we did is that it provides an even stronger piece of evidence for there being a causal effect,” Weisskopf said. “It’s really the pollution doing it.”

CHANGES

Autism, thought to affect one in 68 children in the US, is typically diagnosed after behavioral changes start to develop before the age of 5. Recent studies suggest it might begin when certain brain cells fail to properly mature within the womb.

Researchers focused on 1,767 children born from 1990 to 2002, including 245 diagnosed with autism.

The design of the study and the results rule out many confounding measures that can create a bias, Weisskopf said. The researchers took into account socioeconomic factors that can influence exposure to pollution or play a role in whether a child is diagnosed with autism.

The fact that pollution caused problems only during pregnancy strengthened the findings, since it is unlikely other factors would have changed markedly before or after those nine months, he said in a telephone interview.

IMMUNE SYSTEM

It is likely there is an inflammatory or immune system response to the pollution that reaches the fetus, Weisskopf said. His team is now exploring those biological pathways and mapping autism cases to see if there are any clusters.

He emphasized that many things contribute to the disorder and the absolute risk from pollution might be very small.

FINE PARTICULATES

Fine particulate matter stems from many different sources, including traffic and power plants located hundreds of kilometers away. There is no way to avoid it entirely, though pregnant women might want to try to curtail their exposure when possible, Weisskopf said.

He recommended against trips to cities with high levels of pollution and exercise in traffic-clogged areas during pregnancy.

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