Environmental Chemicals in Breast Milk and the Relationship to Infant Health (Dioxin 2016)
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The benefits of breastfeeding to the infant and mother have been well-documented. It is also well known that breast milk contains environmental chemicals, and numerous epidemiological studies have explored relationships between background levels of chemicals in breast milk and health outcomes in infants and children. In a companion paper, we described the risk assessment approach to exploring implications of the presence of environmental chemicals in breast milk and formula for infants and children. Here we review the epidemiological literature on environmental chemicals in breast milk and formula and the relationship to infant/child health outcomes. This is the first paper to systematically and critically review this literature to (i) explore whether exposure-outcome associations are observed across studies and (ii) assess the literature quality. The epidemiological literature included cohorts from several countries and examined infants/children either once or multiple times over weeks to years. Health outcomes included four broad categories: growth, morbidity, biomarkers, and neurodevelopment. While uncertainties remain, the evidence evaluated does not provide conclusive evidence of consistent or clinically relevant health consequence to infants exposed to environmental chemicals in breast milk at background levels. However, it is also clear that more research would help to better inform our understanding of the potential for health impacts from infant dietary exposures to environmental chemicals. A critical data gap is a lack of research on environmental chemicals in formula and infant/child health outcomes. Based on some non-replicated epidemiological evidence, it may be prudent to strengthen efforts to reduce maternal exposures to environmental chemicals.