Prenatal dioxins and polychlorinated biphenyl (PCB) exposure and neurodevelopment of children : a systematic review

Abstract

Purpose: Dioxins and Polychlorinated biphenyls (PCBs) are neurotoxic. This systematic review reviews the literature onthe association between prenatal dioxin/PCB exposure and neurodevelopment in infants and children.

Methodology: Search of PubMed and Web of Science for cohort studies on prenatal exposure to dioxins/PCBs and neurodevelopment in infants and children was performed. Study design, participant characteristics, measures of prenatal dioxins/PCB exposure, markers of neurocognitive development and the associations between prenatal dioxin/PCB exposure and neurodevelopment from the included studies were extracted and summarized.

Result: 23 articles concerning 9 cohort studies were included. Significant negative associations between dioxins/PCBs exposure and neurodevelopment were reported in 10 out of 12studies on infants and toddlers (<36 months) and 4 out of 11 studies on older children (>36 months). The deficits observed, in any, were all subtle. Different associations between prenatal dioxin exposure and neurocognitive development were observedin cohorts studying children of similar age. Cohortswith multiple neurocognitive assessments at different ages suggested there may be a diminishing impact of prenatal dioxin exposure to neurocognitive ability in older childhood, Differences in the findings may be due to different levels and types of dioxin exposure, different aspect of neurocognitive development being assessed and different adjustment of socioeconomic positions. Further studies exploring the mechanisms are needed for the identification of true associations.

Conclusion: Prenatal dioxin/PCB exposure may have adverse impact on neurocognitive development in children, particularly young infants. Strengthened control of dioxins/PCBs is needed in view of its potential harm of transplacental exposure in infants and children.