Early exposure to air pollution causes harmful changes in the brain seen in autism and schizophrenia, research has shown.
The findings in mice follow previous research linking traffic pollution and higher rates of autism in children.
As in humans, it was mostly male mice that were affected.
Besides suffering physical damage to their brains, they performed poorly in tests of short-term memory, learning ability and impulsivity.
In a series of experiments, scientists exposed mice to levels of air pollution typically found in medium-sized cities during the first two weeks after birth.
Mice examined 24 hours after their last exposure displayed evidence of ‘rampant’ inflammation throughout their brains.
Fluid-filled ventricle chambers on both sides of the brain were also enlarged to two or three times their normal size.
Lead researcher Professor Deborah Cory-Slechta, from the University of Rochester, U.S., said: ‘When we looked closely at the ventricles, we could see that the white matter that normally surrounds them hadn’t fully developed.
‘It appears that inflammation had damaged those brain cells and prevented that region of the brain from developing, and the ventricles simply expanded to fill the space.
‘Our findings add to the growing body of evidence that air pollution may play a role in autism, as well as in other neurodevelopmental disorders.’
The same defects were seen in other groups of mice 40 and 270 days after exposure, suggesting they were permanent.
Brains of all three groups of mice also had raised levels of the nerve message chemical glutamate.
Again, this is seen in humans with autism and schizophrenia.The research, published in the journal Environmental Health Perspectives, focused on ultra-fine carbon particles of the type produced by factories and motor vehicles.
Being so small, the particles can travel deep into the lungs and become absorbed into the bloodstream.
Last year, a study published in the journal JAMA Psychiatry showed that children who spend the first year of life in areas highly polluted by traffic are three times more likely to develop autism.