Pyrethroid insecticide exposure and cognitive developmental disabilities in children: The PELAGIE mother–child cohort

Pyrethroid insecticides are widely used in agriculture
and in homes. Despite the neurotoxicity of these insecticides at high
doses, few studies have examined whether lower-level exposures could
adversely affect children's neurodevelopment.
The PELAGIE cohort included 3421 pregnant women from Brittany, France
between 2002 and 2006. When their children reached their sixth birthday,
428 mothers from the cohort were randomly selected, successfully
contacted and found eligible. A total of 287 (67%) mothers agreed to
participate with their children in the neuropsychological follow-up. Two
cognitive domains were assessed by the Wechsler Intelligence Scale for
Children: verbal comprehension and working memory. Five pyrethroid and
two organophosphate insecticide metabolites were measured in maternal
and child first-void urine samples collected between 6 and 19
gestational weeks and at 6 years of age, respectively. Linear regression
models were used to estimate associations between cognitive scores and
urinary pyrethroid metabolite concentrations, adjusting for
organophosphate metabolite concentrations and potential confounders.
Maternal prenatal pyrethroid metabolite concentrations were not consistently
associated with any children's cognitive scores. By contrast, childhood
3-PBA and cis-DBCA concentrations were both negatively associated with verbal comprehension scores (P-trend = 0.04 and P-trend < 0.01, respectively) and with working memory scores (P-trend = 0.05 and P-trend < 0.01,
respectively). No associations were observed for the three other
childhood pyrethroid metabolite concentrations (4-F-3-PBA, cis-DCCA, and trans-DCCA).
Low-level childhood exposures to deltamethrin (as cis-DBCA
is its principal and selective metabolite), in particular, and to
pyrethroid insecticides, in general (as reflected in levels of the 3-PBA
metabolite) may negatively affect neurocognitive development by 6 years
of age. Whatever their etiology, these cognitive deficits may be of
importance educationally, because cognitive impairments in children
interfere with learning and social development. Potential causes that
can be prevented are of paramount public health importance.

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