Essential and Potentially Toxic Elements in Commercial Milk Formulas: Health Risk Assessment Through a Systematic Review and Meta-analysis

Although commercial milk formulas (CMF) provide essential microelements for child development, they may also contain potentially toxic elements (PTE) that pose health risks depending on their concentration. This systematic review and meta-analysis investigated the presence of essential and toxic elements in CMF. Observational studies assessing element concentrations in three types of CMF (infant formulas [IF], follow-up formulas for older infants [FFI], and products for young children [PYC]) were retrieved from Embase, Scopus, PubMed, Web of Science, Livivo, and Lilacs. Health risk assessment was conducted using the target hazard quotient (THQ). Thirty studies were included in the qualitative synthesis, and eighteen in the meta-analysis. The highest concentrations across CMF types were observed for Al, Fe, Mn and Ni. By WHO regions, the Eastern Mediterranean and the Americas showed the highest levels in IF and FFI, respectively, mainly for Al (IF: 4600 µg kg⁻¹; FFI: 838 µg kg⁻¹), Cu (IF: 2420 µg kg⁻¹; FFI: 2127.23 µg kg⁻¹), and Mn (IF: 984 µg kg⁻¹; FFI: 1853.30 µg kg⁻¹). For PYC, the highest contents were found in the Americas (Al: 1522.47 µg kg⁻¹) and Europe (Mn: 1160 µg kg⁻¹). Risk assessment indicated that daily consumption of IF may be unsafe due to As, Cd, Cu, Co, Fe, methyl-Hg, and Zn. Similar risks were identified in FFI for Cu, Fe, Ni, Se and Zn, and in PYC for Ni. The sum of THQ values exceeded 1 in several countries for all CMF types, suggesting potential non-carcinogenic risks. Continuous monitoring of essential and toxic elements in CMF is necessary to safeguard children’s health.