Children who are exposed to common pesticides, either while in the womb or in the first year of life, may be more likely to develop autism, a new study suggests.
While the researchers stressed that it's premature to say that pesticide exposure actually causes autism, they pointed out that theirs is not the first investigation to sound alarm bells on the dangers that pesticides might pose to brain development.
Still, a child psychiatrist who wrote an editorial accompanying the report noted that much more research is needed to figure out exactly what is going on.
In the study, scientists at University of California, Los Angeles (UCLA) tracked exposure to 11 common pesticides in an agricultural region of California among nearly 3,000 kids with autism born between 1998 and 2010.
These kids were compared with more than 35,000 California residents who had been born within the same time frame, but did not have autism.
All of the chemicals that the scientists tracked had previously been linked to some degree of brain toxicity risk, noted the team led by Dr. Ondine von Ehrenstein. She is an associate professor in the departments of community health science and epidemiology at UCLA.
The result: Women who lived within 2,000 meters (about 1.2 miles) of a highly sprayed area during their pregnancy were 10 percent to 16 percent more likely to have children diagnosed with autism. That risk increased further, to roughly 30 percent, in cases where the child had severe autism (with intellectual disability). Exposure to pesticides during the first year of life bumped the increased risk up to 50 percent.
The findings were published March 20 in the BMJ.
Amanda Bakian, co-author of the editorial and an assistant professor in the division of child and adolescent psychiatry at the University of Utah, noted that the study had some limitations.
"This work looked at the impact of pesticide exposure within 2,000 meters of a person's home," she said. "And the researchers confined their analysis solely to exposure to outside air -- not the air that's inside your homes -- in a highly agricultural area in California's 'bread basket' area. So, we can't necessarily generalize the findings to apply to other settings or environments," Bakian explained.
"And the other thing that's important is that while this study corroborates and builds on previous work, it also suggests that not all children who are exposed to the same pesticides will go on to develop autism," she added.
"Pesticide exposure alone is not the whole story. Other factors are clearly at play that make some children more vulnerable to this exposure than others," Bakian said. "And at this point, we don't know what those are."
As for what concerned parents or expectant mothers can do to limit such potential risk, Bakian acknowledged that the situation is "challenging."
For one, she said that while some of the pesticides that were studied have fallen out of use since the study was conducted, fully eliminating exposure to all pesticides might be a practical impossibility.
"But on a broader level, the question is how can we reduce the impact of this exposure," Bakian said. "How do we apply these chemicals in a way so that they don't have as far-reaching effects? There's a lot more work that needs to be done to figure this out."
The Autism Society of America applauded the research.
"These types of studies are so important to help us understand the underlying mechanisms that may lead to autism spectrum disorders," said Scott Badesch, executive director and CEO of the Autism Society of America.
"We also urge further research like this that might lead to specific public health actions and interventions for individuals and families, he added.
There's more on what might cause autism at the U.S. National Institute of Child Health and Human Development.
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