The rate of autism is increased by 25 per cent in areas that are most intensively sprayed aerially each summer, say researchers from the Penn State Milton S Hershey Medical Center.
The planes are spraying pyrethroid pesticides, which target mosquitoes carrying the encephalitis virus. Encephalitis can cause swelling in the brain and spinal cord.
The researchers looked at statistics from 24 ZIP (postal) code areas in New York state; of these, eight sprayed pesticides from the air, and the rest used more common methods, such as from a vehicle.
The areas that had aerial spraying also had higher levels of the pesticide in the atmosphere, and an increased rate of autism and developmental problems.
The way the pesticides are distributed seems to change the risk for autism, and so the local authorities might want to look at alternative methods to reduce children’s exposure, say researchers.