Insecticide Exposure Linked to Behavioral Problems in Kids

Young children whose mothers were exposed to pyrethroid insecticides while pregnant showed increased rates of behavioral difficulties, a small retrospective French cohort study found.

After adjusting for certain potential confounders, there was a positive association between high prenatal concentrations in maternal urine of certain neurotoxic chemicals found in insecticides, on one hand, and on the other, internalizing behavioral difficulties at age 6 in offspring, reported Jean-François Viel, MD, of the French national research institute INSERM, and colleagues.

Moreover, there was a positive association between high concentrations of certain chemicals in children's urine and externalizing behavioral difficulties at the same age, the authors wrote in Occupational & Environmental Medicine.

Pyrethroids are a class of insecticides that were designed because of concerns about organophosphate insecticides, said the authors -- with pyrethroids "purportedly a safer alternative for humans and the environment."

The authors had previously used the PELAGIE mother-child cohort to examine prenatal and childhood exposure to pyrethroid insecticides and neurocognitive abilities. They found a link between childhood exposure and poorer neurocognitive abilities, but there was no association between prenatal exposure and neurocognitive abilities in objective testing.

The current study was an examination of prenatal exposure, as measured by urinalysis, in relation to behavioral abnormalities. It used data on 287 mother-child pairs from the PELAGIE cohort, including urine samples from the mothers during pregnancy (6-19 gestational weeks) and in children at age 6.

Children completed the Strengths and Difficulties Questionnaire and mothers completed the Wechsler Adult Intelligence Scale (3rd Version). At the beginning of the study, mothers were mostly older than 27, multiparous, and college graduates. Both mothers and children were healthy -- with most reporting living in non-smoking homes, where children got adequate sleep and participated in extracurricular activities.

The pyrethroid metabolite trans-dimethylcyclopronane carboxylic acid (trans-DCCA) was found in nearly all mothers (99.9%) and children (96.5%), followed by cis-dibromonovinyl (cis-DBCA) at 68.3% of mothers and 85.2% of children.

But it was high concentrations of prenatal cis-DCCA that were associated with internalizing difficulties in children, and high concentrations of 3-phenoxybenzoic acid (PBA) in children that were linked with externalizing difficulties.

The authors also found that there was a more than twofold increased risk of abnormal or borderline social behavior associated with children who had the highest 3-PBA levels (OR 2.93, 95% CI 1.27-6.78). They also noted a nonsignificant trend toward increased risk for children who had intermediate levels of 3-PBA (OR 1.91, 95% CI 0.80-4.57).

They concluded that the results, along with the prior study that linked pyrethroid insecticides with cognitive disabilities, support a "potential risk to neurodevelopment from pyrethroid insecticides," and that remediating the potential causes of these neurodevelopmental deficits is "of paramount public health importance."

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