Tuesday , January 19 2021

A study on the threshold of air pollution associated with the risk of autism, says



Autism spectrum disorder, developmental disability, is characterized by problems of communication and social interaction with accompanying repetitive patterns of behavior.
Leaf Pagalan, lead author of the study and member of the Faculty of Health Sciences at the University of Simon Fraser, warns that a study published Monday in the medical journal JAMA Pediatrics showed only a link between prenatal exposure to nitric oxide and levels of autism. This does not prove that air pollution causes autism.

Experts emphasize that the exact causes of autism remain unknown, and some say that the researchers in this study did not analyze every potential risk factor.

However, the study “adds to the growing concern that there can be no safe levels of exposure to air pollution,” Pagalan wrote in an e-mail.

“Not only did we gain access to rich data, which allowed us to develop one of the largest studies to date, but we were also able to conduct this research in a city with a relatively lower level of air pollution,” he said.

More than 100,000 children studied

Pagalan and his colleagues analyzed the records of 129,436 children born in Vancouver from 2004 to 2009.

“We analyzed data on air pollution in Vancouver over the same period to assess the impact of air pollution on a pregnant woman,” he said. "Their children were monitored for at least 5 years to find out if they were diagnosed with autism spectrum disorders."

Overall, about 1% of children were diagnosed with autism at the age of 5, the researchers found. They compared the rates of autism among children of women who were exposed to the least amount of air pollution during pregnancy compared to those among children of women who were most affected.

All three measurements of air pollution (particulate matter, nitrogen dioxide and nitrous oxide) showed a similar relationship with autism.

Autism Fast Facts

The chances of developing autism among children prenatally subjected to elevated levels of PM2.5 (particle size less than 2.5 micrometers in diameter) were 1.04%, the probability of autism in children exposed to higher levels of nitrogen dioxide was 1.06%, The chances of autism in children exposed to higher levels of nitric oxide were 1.07%. This final increased risk turned out to be “statistically significant”, which means that he crossed the line from random odds and shows true relationships.

Studies in the United States, including Los Angeles County, have shown that living near highways where air quality is poor may be a trigger for autism, but three studies in Europe — including Sweden, the Netherlands, Spain and Italy – have not proven their association, say the authors of the new study.

Pagalan said that the causes of autism are not fully known. “They are complex and have many factors, but researchers recognize that genetics and environmental factors play a role,” he said.

Experts say that any link between air pollution and autism is small at best.

Autism takes place in families, and its causes remain unknown

Robin P. Goin-Kochel, deputy director of research at the Texas Children's Autistic Center and assistant professor at Baylor College of Medicine, said families should "take these results with salt." Goin-Kochel, who did not participate in the new study, stressed that he found only an association that “does not equate causality.”

However, in her opinion, the authors “beautifully addressed” some flaws in previous studies of the same subject. For example, criteria for children with autism included only those who received the “gold standard” diagnosis based on data from the autism assessment network in British Columbia.

However, other important factors were not included in the analysis, she said, for example, socio-economic status, which, as has been shown, is associated with autism.

Scientists say that blood and urine testing for autism may help in earlier diagnosis.

“In addition, the focus was on the language environment of mothers, and it is possible that the workplaces of mothers have different ecological composition that may be important to consider,” she wrote in an e-mail. “Perhaps these pollutants and / or other influences affect fathers and their sperm quality.”

James Cusack, director of science at Autistica, a British charity, told the Science Media Center that a new study "should not concern people who are thinking of having children."

“Autism is highly genetic, we know this because it works in families,” said Cusack, who did not participate in the study. He added that the researchers found only a “slight increase” in the likelihood of having an autistic child for women exposed to more air pollution, in particular nitric oxide. “Other differences that have not been measured, such as genetic differences, may explain this increase. This study does not provide evidence that air pollution causes autism. ”

Kevin McConvey, an honorary professor of applied statistics at The Open University, told the Science Media Center that the new study is “cautious,” but the results are “a little difficult to interpret.”

“In a broad sense, the results of the study were the same for all three pollutants,” said McConway, who did not participate in the new studies. However, only nitric oxide went to the "traditional margin of statistical significance," he said, "and only slightly higher."

“In such studies, it’s really impossible to truly understand the reasons for what,” he said. “Perhaps air pollution does affect [autism] risk, or perhaps not. " Although the study "adds more evidence," he concluded, "we are very far from knowledge."

Pagalan said that because of the lack of treatment for autism, “identifying risk factors for the environment helps identify opportunities for prevention.”


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