Authors
Ribas-Fito, N., Cardo, E., Sala, M., Eaulalia de Muga, M., Mazon, C., Verdu, A., Kogevinas, M., Grimalt, J.O., Sunyer, J.

Title:
Breastfeeding, exposure to organochlorine compounds, and neurodevelopment in infants

Source:
Pediatrics. 111(5):e580-e585. 2003.

Summary:
Although a number of studies have reported a positive relationship between high level exposures of polychlorinated biphenyls (PCBs) and neurological and behavioural dysfunctions in humans and animals, limited evidence exists as to the effects of other organochlorine compounds. In addition, an ongoing debate continues regarding the association between breastfeeding and improved neurodevelopment. Although breastfeeding is known to increase organochlorine exposure among infants, a recent study has reported higher cognition abilities among breastfed infants as compared to formula-fed infants. Another recent study has shown a positive association between long durations of breastfeeding and intelligence in adulthood.

The authors of the present investigation sought to further investigate the impact of organochlorine exposure on prenatal and postnatal neurodevelopment in infants, and the relationship between breastfeeding and organochlorine exposure in utero. A birth cohort of 92 mother-infant pairs was recruited from a population located in the vicinity of an electromagnetic factory that had been producing chlorinated solvents since 1898 (Flix, Catalonia, Spain). Although the production of DDT and PCB has been discontinued, the primary pollutants within this study area are organochlorines. In particular, the levels of hexachlorobenzene (HCB) detected in the cord serum of infants from this population were among the highest ever reported. In addition, as a result of past organochlorine chemical use in agriculture, high levels of p,p'DDE have also been found among the population.

At 13 months of age, the Bayley Scales of Infant Development (Mental Development Index (MDI) and the Psychomotor Developmental Index (PDI)) and the Griffiths Mental Development Scales were used to assess the children's mental and psychomotor development. Gas chromatography was used to measure HCB, p,p'DDE, and PCB levels in cord serum. Questionnaires administered following delivery and at 13 months for the purpose of obtaining information on fetal exposure to alcohol and cigarette smoke, obstetric history, socioeconomic background, maternal intelligence, and type and duration of breastfeeding.

Levels of p,p'DDE in cord serum were negatively associated with both the MDI and the PDI. The association between PCB exposure and PDI was only marginally significant. Prenatal exposure to HCB had no effect on either the MDI or the PDI. A positive correlation existed between the duration of breastfeeding and MDI/PDI performance. However, those infants who had higher p,p'DDE cord serum levels and were breastfed short-term had the lowest MDI and PDI scores overall.

Numerous studies have suggested that the prenatal nervous system is more vulnerable to the detrimental effects of organochlorine compounds than the postnatal nervous system. In addition, as exposures to environmental contaminants are unintentional and the degree of the exposure unknown, the issue of the effects of organochlorine exposure on neurodevelopment is one of concern. However, since long-term breastfeeding seems to be beneficial with respect to neurodevelopment, Ribas-Fito et al. recommend that pediatricians encourage long-term breastfeeding to help counterbalance the potential impact of organochlorine exposure through breast milk.