Some Insecticides May Impair Brain Development In Young Children: Study

The findings of new research suggest that exposure to certain pesticides during pregnancy may impair the brain development of the child. 

In a study published by the journal Environmental International, researchers examined data on nearly 300 mother and child pairs, examining the risks associated with exposure to pyrethroid insecticides during pregnancy. The findings suggest that exposure may increase the risk that children experience impaired cognitive development, specifically in verbal comprehension and working memory.

The mother and child pairs were randomly chosen from a group of more than 3,000 participants in the PELAGIE cohort from Great Britain and France, between 2002 and 2006.

Urinary concentrations of seven metabolites were recorded from the mother’s samples taken between 6 to 19 weeks gestation, and a sample from the child taken at 6 years of age. Five pyrethroid and two organophosphate insecticide metabolites were measured.

Researchers later tested the cognitive function of the children.

Childhood metabolite levels of two pyrethroids, 3-PBA and cis-DBCA, were both negatively associated with verbal comprehension scores and working memory scores. There was no association observed for the other three metabolites, 4-F-3-PBA, cis-DCCA and trans-DCCA, or for maternal prenatal pyrethorid metabolite concentrations linked to children’s cognitives scores.

Overall, higher urinary pyrethroid concentrations were association with neurocognitive decline.

Pyrethroid insecticides are a family of insecticides commonly in crops, veterinary treatment as an anti-parasitic, in lice shampoo and mosquito repellants. They work by blocking neurotransmission in insects, leading to paralysis.

In recent years, evidence has shown pyrethroids can cause neurotoxicity in humans. They has been shown to cause neurotoxicity at high doses, but low-level exposure studies have not been conducted. This is the first study to do so, and researchers warn more studies are needed.

“The consequences of a cognitive deficit in children for their learning ability and social development constitute a handicap for the individual and for society,” said Jean-François Viel, co-author of the study. “The research effort needs to be pursued in order to identify causes that could be targeted by preventive measures.”

Childhood exposure to pyrethorids are very different from for adult exposuress because of a child’s closer proximity to the ground land the amount of pyrethroids found in dust, which also stores the pollutants. Children also experience exposure through hand to mouth contact and lice shampoos. In children pyrethroids are mainly absorbed through the digestive system and the skin.

The research was conducted by the Institute of Research in Environmental and Occupational Health, Rennes (IRSET) in association with the Laboratory for Developmental and Educational Psychology (LPDE).