Babies in the womb who are exposed to OP (organophosphate) pesticides have a higher risk of poorer intellectual development by the time they are 7 years old, US researchers revealed in the journal Environmental Health Perspectives.
Organophosphates are any of many organic compounds which contain phosphorous and are used as pesiticides and fertilizers. They irreversibly inactivate acetylcholinesterase, an enzyme which is vital for proper nerve function in insects and animals, including humans. Commonly used organophosphates have included diazinon, malathion, phosmet, azinphos methyl, methyl parathion, chlorpyrifos, dichlorvos, tetrachlorvinphos, and parathion.
Organophosphate pesticides are commonly sprayed on crops. Trace amounts can be found in green beans, berries, and some other fruit and vegetables sold in high street shops and supermarkets. Although pesticides are available for domestic (home) use, levels are much lower than found in crop farming.
Maryse F. Bouchard and team set out to determine whether there might be a link between prenatal and postnatal OP pesticide exposure and cognitive abilities in schoolchildren.
They carried out a birth-cohort study among farmworker families belonging to an agricultural community in California – they were mainly Latinos. OP pesticide exposure was assessed by measuring DAP (dialkyl phosphate) metabolites in urine samples, which were collected during pregnancy and from children aged 6 months, as well as when they were 1, 2, 3.5 and 5 years old. They used the Wechsler Intelligence Scale for Children-IV on 329 kids – they were all seven years old. Adjustments were made for factors which might have an impact on a child’s IQ, such as the mothers education and intelligence, the HOME score, and language of cognitive assessment.
The researchers found that the pregnant women with the highest levels of DAP metabolites ended up having 7-year-old children with lower-than-average IQs. An average IQ score in this study was 100. Children with the highest quintile of DAP levels when in the womb had IQ scores 7 points below those in the bottom quintile when they were 7 years old.
Senior study author, Brenda Eskenazi, Ph.D., from the University of Berkeley, California, said:
“That’s not unlike the decreases we see in children with high lead exposure.”
The authors stressed that urinary DAP concentrations in babies after they were born appeared to have no impact on future IQ levels – the link was only found when DAP levels were high in fetuses (babies still in the womb).
In an Abstract in Environmental Health Perspectives, the authors concluded:
“Prenatal but not postnatal urinary DAP concentrations were associated with poorer intellectual development in 7-year-old children. Maternal urinary DAP concentrations in the present study were higher, but nonetheless within the range of levels measured in the general U.S. population.”
Maryse F. Bouchard, Jonathan Chevrier, Kim G. Harley, Katherine Kogut, Michelle Vedar, Norma Calderon, Celina Trujillo, Caroline Johnson, Asa Bradman, Dana Boyd Barr, Brenda Eskenazi
Environmental Health Perspectives doi:10.1289/ehp.1003185
Written by Christian Nordqvist