AmericaBlog passes on details of a report on the levels of pesticides found in children:
The peer-reviewed study found that the urine and saliva of children eating a variety of conventional foods from area groceries contained biological markers of organophosphates, the family of pesticides spawned by the creation of nerve gas agents in World War II.
When the same children ate organic fruits, vegetables and juices, signs of pesticides were not found.
We know that high levels of organophosphates are dangerous to humans (farmers commonly use them on livestock, and those that do suffer from higher than average rates of neurological illness). Lower levels aren’t linked to anything specific at the moment, but that’s possibly an artifact of current medical knowledge; observing the effects of small doses of anything is hard, both because the effects take time to accrue, and it’s difficult to separate out one factor among many others when you’re looking at someone’s entire life for an extended period.