pesticides

A study of 265 New York City minority children has found that those born with higher amounts of the insecticide chlorpyrifos had lower IQ scores at age 7. Those most exposed (top 25%) scored an average 5.3 points lower on the working memory part of the IQ test (WISC-IV), and 2.7 points lower on the full IQ test, compared to those in the lowest quartile.

The children were born prior to the 2001 ban on indoor residential use of the common household pesticide in the US. The babies' umbilical cord blood was used to measure exposure to the insecticide.

A study involving 614 middle-aged vineyard workers has found that those who were exposed to pesticides were five times as likely to perform more poorly on cognitive tests compared to those not exposed, and twice as likely to show cognitive decline over a two-year period.

A study involving 725 black and Dominican pregnant women living in New York and, later, their 3-year-old children, has found that children who were more highly exposed to PBO in personal air samples taken during the third trimester of pregnancy scored 3.9 points lower on the Bayley Mental Developmental Index than those with lower exposures. This is a similar effect size to that of lead exposure.

A study following over 300 Mexican-American children living in an agricultural community has found that their prenatal exposure to organophosphate pesticides (measured by metabolites in the mother’s urine during pregnancy) was significantly associated with attention problems at age 5. This association was stronger among boys, and stronger with age (at 3 ½ the association, although present, did not reach statistical significance — perhaps because attention disorders are much harder to recognize in toddlers).