Infant exposure and risk assessment to metals through breast milk from Spanish lactating mothers.

Heavy metal toxicity is related with a number of diseases, but the problem increases when toxic metals are found in breast milk, the basic food item in a vulnerable age group. In this study, we assessed the levels of seven essential (i.e., Co, Cu, Mn, Mo, Se, Zn and V) and 13 toxic (i.e., Sb, As, Ba, Be, Cd, Cs, Pb, Hg, Ni, Pt, Th, Tl and U) metals in human milk of 118 lactating mothers who took part in a Spanish human biomonitoring project (BETTERMILK). The highest detection frequency (DF) was 100% for Cu, Zn, Se and Cs; 93% for As; and 84% for Hg. The rest of elements had DF below 40%. The geometric mean (GM) concentrations were below LoQ for 14 elements and the maximum level found was 2856 ng/g for Zn. The newborns' estimated weekly/daily intake of toxic and essential metals through human milk was lower than their toxic reference values established by official organisms. To our knowledge, this is currently the first risk assessment study of infants to the most toxic metals such as Hg, As, Cd, Pb, Se and Zn through breast milk in Spain.