Numerous studies have implicated high pesticide levels in everything from cancer to Alzheimer's disease. (moneysense.ca)
One study measured markers of organophosphate pesticides like malathion or diazinon (commonly used in agriculture) in the blood or urine of children and their mothers, then checked the developmental abilities of the children; it found a higher rate of autism - like disorders in children with higher pesticide levels. (health.com)