Abstract
Introduction: The early stages of life are vulnerable to exogenous chemical exposures because of infants’ rapid development and incomplete metabolic activities. Emerging evidence suggests that heavy metals in breast milk may be linked to the poorest developmental outcomes. This systematic review was designed to summarize the association between heavy metal exposure in breast milk and health outcomes in infants.
Methods: PubMed, ScienceDirect, Web of Science, Scopus, and Google Scholar were searched to extract original animal and human studies published until December 2024, with no date restrictions. Irrelevant and duplicate studies were screened out, and data extraction was performed. The quality of the included articles and the risk of bias were assessed using the OHAT and the Newcastle-Ottawa scale tools.
Results: Firstly, 5019 studies were retrieved via the search strategy, and 8 articles (3 animal and 5 observational studies (3 cross-sectional and 2 cohort)) were included in this review. Except for one case, all of the included animal and human studies indicated that heavy metal exposure in breast milk was significantly associated with negative health outcomes in infants. Of the three human studies evaluating the effects of mercury exposure on infants’ health, two found that mercury impairs neurodevelopmental performance and induces oxidative stress. Other included studies also reported that cadmium exposure through breast milk was associated with oxidative DNA damage, and lead exposure negatively influenced the mental development of the offspring.
Conclusion: Our findings demonstrated that heavy metal exposure in breast milk can negatively impact health outcomes in infants. Future well-designed human studies with large sample sizes are warranted to clearly establish these findings.