Background:

Breast milk is the best source of nutrition for the newborn infant. However, since all infants cannot be

breast-fed, there is a need for background data for setting adequate daily intakes. Previously, concentration data on

major essential elements and some toxic elements in breast milk, based on different analytical techniques, have

been published. There is no recent study on a large number of metals and trace elements in breast milk, using a

sensitive analytical method for determination of low element concentrations.

Methods:

Breast milk concentrations of 32 metals and elements in early lactation (days 14–21) were determined in

a random sample of first time Swedish mothers (n = 60) using inductively coupled plasma mass spectrometry

(ICPMS).

Results:

There were small inter-individual concentration variations in the macroelements Ca, K, Mg, P and S, and

striking similarities across studies and over time, supporting a tight regulation of these elements in breast milk.

Large inter-individual and over time differences were detected for Na concentrations, which may reflect an increase

in salt consumption in Swedish women. Large inter-individual differences were also detected for the microelements

Co, Cr, Mn and Mo, and the toxic metals As, Cd, Pb, Sb and V. Arsenic and B were positively correlated with fish

consumption, indicating influence of maternal intake on breast milk concentrations. Observed differences in breast

milk element concentrations across studies and over time could be attributed to the timing of sampling and a

general decline over time of lactation (Cu, Fe, Mo, Zn), a possible lack of regulation of certain elements in breast

milk (As, B, Co, Mn, Se) and time trends in environmental exposure (Pb), or in some cases to differences in analytical

performance (Cr, Fe).

Conclusions:

This study provides reliable updated information on a number of metals and elements in breast milk,

of which some have not previously been reported.

Keywords:

Breast milk, Toxic metals, Trace elements, Infant exposure, Microelements, Macroelements