The first eight weeks after conception seem to be the most vulnerable time, and the risk increases dramatically if, during that time, their mothers were living close to farms that had used pesticides, and especially dicifol and endosulfan.
Researchers from the National Institutes of Environmental Health Sciences in the USA made the connection after they studied the records of 465 children with autism who were born between 1996 and 1998 in California.
On average, the risk increased six-fold, although this varied depending on the amount of pesticides used and the distance of the mother from the farm. Women who lived within a 500-metre radius of the farm were at greater risk.
(Source: Environmental Health Perspectives, 2007; doi:10.1289/ehp.10168).
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