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, in particular, increased particulate matter and nitrogen dioxide pollution „during pregnancy and during the first years of life“ an increased risk of autism. Their findings have the researchers around Heather Volk from the University of Southern California in the journal „Archives of General Psychiatry“ released.

28/11/2012

Previous research has already shown that genetic and environmental factors can have a major impact on the development of autism. The US researchers took this as an opportunity to examine possible connections between air pollution and the onset of autism. A total of 279 children with autism and 245 children with normal development formed the sample of the current US study. The scientists determined based on the place of residence of the mothers or children in the first year of life, the exposure of the subjects to traffic-related air pollution. It showed that the children with autism came much more often from regions in which an increased air pollution was observed. According to the researchers, the risk of an autism disorder was around three times higher in the most polluted homes than in the least polluted residential areas.

Correlation between air pollution and autism checked in the model
The population-based case-control study of US scientists relies on the data of the children from the study „Childhood Autism Risks from Genetics and the Environment“ in Californians, Heather Volk and colleagues report. The researchers used the mother's address information from the birth certificate and a supplemental 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 major roads was taken into account. The researchers also resorted to the measurement results of the Ministry of Environment of the air quality. In one „logistic regression model, the estimated and measured pollutant levels were compared for children with autism and children with normal development“, so the statement of the US scientists.

Autism in homes with heavy air pollution three times more common
The calculations showed that there is a significant relationship between the risk of autism and the air pollution at the place of residence during pregnancy or the first year of life of the child. The children with autism were therefore increasingly from dwellings with particularly poor air quality. The researchers were particularly struck by the increased occurrence of autism in children who were exposed to increased nitrogen dioxide and particulate matter pollution (particle size of 2.5 and 10 microns, PM 2.5 and PM 10). Overall, the risk of autism at locations with the highest level of air pollution was about three times higher than in the locations with the best air quality, according to the results of the US scientists. „Further epidemiological and toxicological investigations“ are now needed to clarify clearly whether there is a causal link between the risk of autism and air pollution.

Environmental factors as an autism trigger
The recent study by US scientists once again confirms the suspicion that autism is closely related to environmental factors. It was not until the middle of the year that researchers from the Idaho State University School had proven in animal experiments that psychotropic drugs in drinking water can promote autism. Even small residues of drugs against depression and epilepsy in the water of experimental fish (fat head minnows), have caused autism-typical changes in the brain in animals, the researchers reported in early June in the journal „PLoS ONE“. The results are quite transferable to humans, since the affected genes in the minnows are the same as in persons with hereditary autism predisposition, explained study director Michael Thomas from the Institute of Biological Sciences at 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 occurrence of autism. The relationship between the release of pollutants into the environment and an increased incidence of autism may have been significantly underestimated so far. (Fp)

Also read:
Autism curable in the future?
Psychotropic drugs in drinking water cause autism
Genetic mutation in autism due to sperm
Solvents provoke autism in children
Study: Autism already detectable in babies
Brain: where moral decisions are made

Picture: Günter Havlena