Kokroko, J., Kogut, K., Harley, K., & Eskenazi, B.; “Prenatal beta-Hexachlorocyclohexane (beta-HCH) Exposure and 7-Year Child IQ in the CHAMACOS Birth Cohort;” Neurotoxicity Research, 2020, 37(3), 553-563; DOI: 10.1007/s12640-020-00160-w.

ABSTRACT:

Fetal and infant exposures to beta-hexachlorocyclohexane (beta-HCH) occur through placental and breastmilk transfers. No studies have examined the relationship between beta-HCH and child intelligence quotient (IQ). This study examined associations between in utero beta-HCH exposure and cognitive development in 7-year-old children. Data from women and children (n = 256) participating in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) birth cohort study were evaluated. We assessed exposure to beta-HCH by measuring maternal serum concentration during pregnancy. We administered the Wechsler Intelligence Scale for Children (WISC), Fourth Edition, to children at age 7. Analyses were adjusted for maternal age, country of birth, work status, parity, and other pesticide exposures, language used for child cognitive assessment, and duration of breastfeeding. Higher serum beta-HCH concentrations were associated with higher cognitive scores across all unadjusted models for the full-scale and sub-scale cognitive tests. In the adjusted models, a 10-fold increase in serum beta-HCH concentration was associated with a 4.5-point increase in Working Memory IQ score (95% CI, 0.6 to 8.3; p = 0.02). We observed no significant interaction by length of breastfeeding or sex on associations. Our findings suggest that prenatal exposure to beta-HCH is not adversely related to IQ at age 7 in a cohort of Mexican American children with fairly high exposure in utero as measured by maternal serum levels. Future research must replicate these findings in other study cohorts of women and children.