Air pollution as a cause of autism

Air pollution appears to be directly related to the risk of autism. US researchers from the University of Southern California have found that increased levels of particulate matter and nitrogen dioxide in particular "during pregnancy and during the first years of life" cause an increased risk of autism. The researchers led by Heather Volk of the University of Southern California have published their results in the journal "Archives of General Psychiatry".

It was already known from previous studies that genetic and environmental factors can have a significant impact on the development of autism. The US researchers took this as an opportunity to examine possible connections between air pollution and the occurrence of autism. A total of 279 children with autism and 245 children with normal development formed the sample of the current US study. Based on the place of residence of the mothers or children in the first year of life, the scientists determined the exposure of the test subjects to traffic-related air pollution. It was found that the children with autism came from regions in which increased air pollution was found significantly more often. According to the researchers, the risk of autism was around three times higher in the most polluted places of residence than in the places with the least air pollution.

Connection between air pollution and autism verified in the model The population-based case-control study by the US scientists is based on the data from the children from the study "Childhood Autism Risks from Genetics and the Environment" in California, Heather Volk and colleagues report. The researchers used the mother's address information from the birth certificate and a supplementary questionnaire to estimate air pollution during pregnancy and the child's first year of life. For example, the proximity of the place of residence to main roads was taken into account. The researchers also used the measurement results of the Ministry of Environmental Protection on air quality. In a "logistic regression model, the estimated and measured levels of pollutants for children with autism and children with normal development were compared," according to the US scientists.

Autism in places with heavy air pollution three times more often The calculations showed that there is a significant correlation between the risk of autism and the air pollution in the place of residence during pregnancy or during the child's first year of life. The children with autism therefore increasingly came from places of residence with particularly poor air quality. The scientists particularly noticed the increased incidence of autism in children who were exposed to increased nitrogen dioxide and fine dust pollution (particle sizes of 2.5 and 10 micrometers; PM 2.5 and PM 10). Overall, the risk of autism in locations with the greatest air pollution was around three times higher than in locations with the best air quality, according to the US scientists. "Further epidemiological and toxicological studies" are now required to clarify clearly whether there is a causal relationship between the risk of autism and air pollution.

Environmental factors as a trigger for autism The current study by the US scientists once again confirms the suspicion that autism is closely related to environmental factors. It was only in the middle of the year that researchers at Idaho State University School had shown in animal experiments that psychotropic drugs in drinking water can promote autism. Even small residues of medication for depression and epilepsy in the water of experimental fish (fat-head minnows) triggered autism-typical changes in the animals' brains, the researchers reported in early June in the journal "PLoS ONE". The results are certainly transferable to humans, since the genes affected in the minnows are the same as in people with an inherited autism predisposition, explained study leader Michael Thomas from the Institute of Biological Sciences at the Idaho State University School. In his opinion, future studies should check whether the breakdown products of the drugs in drinking water may cause an increased incidence of autism. The relationship between the entry of pollutants into the environment and an increased incidence of autism may have been significantly underestimated. (fp)

Also read:
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Picture: Günter Havlena /

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