Determinants of potentially toxic element concentrations in human milk: a scoping review

Human milk is recognized as the gold standard for infant nutrition. However, increasing environmental contamination by potentially toxic elements has raised concerns about infant exposure during lactation. This study aimed to map and synthesize current scientific evidence on factors associated with these elements in human milk. A scoping review was conducted following JBI methodology, with searches in PubMed, Scopus, Embase, BVS, and the CAPES Journals Portal. Eligible studies were original articles published between 2015 and 2025 that quantified potentially toxic elements in human milk and examined associated factors. Of the 3,151 records identified, 44 studies met the inclusion criteria, with most using cross-sectional designs and originating from Asia and Europe. ICP-MS was the most frequently employed analytical technique. Across 22 investigated elements, 11 showed associations with explanatory factors, with arsenic, cadmium, lead, and mercury most often assessed. At the individual level, element concentrations were linked to maternal diet, cosmetic use, passive smoking, and selected biological and environmental characteristics. Contextual evidence indicated higher concentrations in mining, industrialized, and coastal areas. Overall, the literature shows substantial methodological heterogeneity and limited multivariable modeling, underscoring the need for improved analytical standardization and structural actions to reduce environmental exposure sources while safeguarding breastfeeding.