Prenatal exposure to the organophosphate pesticide chlorpyrifos was associated with brain structure changes and poorer motor performance in 270 children aged 6 to 14 years, according to a study published in JAMA Neurology.
The researchers examined children whose mothers were Dominican or African American and enrolled during pregnancy in northern Manhattan and the South Bronx.
Higher exposure was associated with thicker frontal, temporal, and posteroinferior cortices and thinner superior parietal cortex, with local white-matter volumes reduced in overlapping regions. Within the internal capsule, exposure correlated with higher fractional anisotropy and lower average diffusion coefficient, consistent with increased myelination or greater axon packing density. Arterial spin labeling demonstrated lower regional cerebral blood flow throughout much of the brain.
Magnetic resonance spectroscopic imaging showed lower N-acetyl-L-aspartate (NAA) within deep white-matter tracts and insular cortex, an index of neuronal integrity/density. Behaviorally, exposure was inversely associated with fine motor speed (β, −0.30) and motor programming (β, −0.27), with disproportionate effects in the nondominant hand.
“Scatterplots were without evidence of an exposure threshold below which associations were absent,” wrote lead author Bradley S. Peterson, MD, of the Institute for the Developing Mind at Children's Hospital Los Angeles, and colleagues.
Exposure to chlorpyrifos was quantified at delivery from umbilical cord or maternal plasma by isotope dilution gas chromatography high-resolution mass spectrometry. Children completed magnetic resonance imaging (MRI) protocols—anatomical MRI for cortical thickness and local white-matter volumes, diffusion tensor imaging for fractional anisotropy and average diffusion coefficient, arterial spin labeling for regional cerebral blood flow, and magnetic resonance spectroscopic imaging for NAA—and standardized cognitive and motor testing.
The study controlled for child age, sex, race and ethnicity, maternal education, material hardship, and home stress. Additional statistical checks confirmed the reliability of the findings.
Full disclosures can be found in the published study.
Source: JAMA Neurology