Worldwide arsenic levels in human breast milk and probabilistic health risk assessment: A systematic review and meta-analysis

Background: The exposure to toxic metals is a major global health concern due to their stability, bioaccumulation, and high toxicity. These metals can be transmitted to the fetus through the placenta and exposure can last throughout life. This systematic review focused on the potential risks of arsenic (As) in breast milk to newborns and infants. Methods: Multiple keywords, such as “human milk” and “breast milk”, associated with “toxic metal”, “heavy metal” or “arsenic” were used to search related databases. Of the 151 articles found, 45 studies were eligible for qualitative review, and 34 were included in the meta-analysis. Results: The lowest and highest levels of arsenic were found to be 0.04 ± 0.70 and 27.75 ± 28.30 μg/L, respectively. The overall pooled average concentration (95% CI) of arsenic in breast milk was 0.11 (95% CI: 0.11, 0.12). The results indicated that infants who consume breast milk are within a safe limit for cancer risk. Conclusion: The exposure to significant metals is associated with disease development. Therefore, ongoing knowledge creation through mental acts and continuous observation is necessary to better understand the effects of heavy metals in future studies.