Risk assessment of trace elements in human breastmilk in a Northern Italy population

Background: Breastfeeding is the main source of nutrition in newborns, thus risk assessment of dietary intake of trace elements represents a relevant public health topic. Methods: Using a cross-sectional study design, we recruited mother-infant pairs from women who gave birth between 2015 and 2017 at the Obstetrics and Gynecology Unit of the University Hospital of Modena, Northern Italy. We investigated sociodemographic and pregnancy characteristics of mothers and newborns and we collected human mature milk samples between 30 and 40 days after childbirth to evaluate content of trace elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se and Zn) using inductively coupled plasma mass spectrometry. We assessed the estimated dietary intake (EDI) of trace elements and compared results with both reference values suggested by main regulatory agencies. Results: In the 195 mother-infant pairs, the mean women age was 33.1 years, mainly resident in urban areas (80 %). As regards smoking status, 3.6 % and 31.3 % of women were current and former smokers. Median trace elements concentrations (in µg/L) were As: 0.09; Cd: 0.02, Cr: 0.09; Cu: 408.0; Fe: 265.25; Mn:2.48; Ni: 1.20; Pb: 0.02; Se: 11.14; Zn: 2264. We found a positive association with maternal age for Fe and Ni, and slightly higher concentrations of Cu, Fe, Ni and Se in mothers living in urban areas. Current smokers showed the highest concentrations of As, Cu, Fe, Mn, but the lowest of Se. Risk assessment comparing EDI with reference values from regulatory agencies showed generally adequate intake, and all median EDIs were below the upper levels. However, when considering 95th of EDIs, some elements demonstrated values closer to the corresponding upper limit, namely Zn, Pb, As, and Cu. Conclusions: Our findings indicate a general safe dietary intake of the investigated trace elements, but highlight the need to strengthen the recommendations to avoid smoking during pregnancy and lactation and to continuously monitor human milk content to protect newborns.