Prenatal exposure to organochlorine pesticides and early childhood communication development in British girls

Background: The developing brain is susceptible to exposure to neurodevelopmental toxicants such as pesticides. Aims: We explored associations of prenatal serum concentrations of hexachlorobenzene (HCB), beta-Hexachlorocyclohexane (beta-HCH), 2,2-Bis(4-chlorophenyl)-1,1-dichloroethene (p,p'-DDE) and 2,2-Bis(4-chlorophenyl-1,1,1-trichloroethane (p,p'-DDT) with maternal-reported measures of verbal and non-verbal communication in young girls. Study design and methods: We studied a sample of 400 singleton girls and their mothers participating in the Avon Longitudinal Study of Parents and Children (ALSPAC) using multivariable linear regression models adjusting for parity, Home Observation Measurement of the Environment (HOME) score, maternal age and education status, and maternal tobacco use during the first trimester of pregnancy. Exposure and outcome measures: Maternal serum samples (collected at median 15 wks. gestation [IQR 10, 28]) were assessed for selected organochlorine pesticide levels. Communication was assessed at 15 and 38 months, using adapted versions of the MacArthur Bates Communicative Development Inventories for Infants and Toddlers (MCDI). Results: At 15 months, girls born to mothers with prenatal concentrations of HCB in the highest tertile had vocabulary comprehension and production scores approximately 16% (p = 0.007) lower than girls born to mothers with concentrations in the lowest tertile. This association varied by maternal parity in that the evidence was stronger for daughters of nulliparous mothers. At 38 months, girls born to mothers with prenatal concentrations of HCB in the highest tertile had mean adjusted intelligibility scores that were 3% (p = 0.03) lower than those born to mothers with concentrations in the lowest tertile; however, results did not vary significantly by parity. Maternal concentrations of beta-HCH and p,p'-DDE were not significantly associated with MCDI scores at 15 or 36 months. p,p'-DDT had an inconsistent pattern of association; a significant positive association was observed between p,p'-DDT with verbal comprehension scores at 15 months; however, at 38 months a significant inverse association was observed for p,p'-DDT with communicative scores. This inverse association for p,p'-DDT among older girls tended to be stronger among daughters of mothers who had lower depression scores. Conclusions: Organochlorine pesticide exposure in utero may affect communication development.