Levels of 26 elements in infant formula from USA, UK, and Nigeria by microwave digestion and ICP–OES

Abstract

The presence of toxic elements in powdered and liquid infant milk may create significant health problems for infants. Babies (0–6 months old) may be more at risk because their only food may be infant formula. In this study, infant formula samples sold in major supermarket chains in Nigeria, the UK and USA were analyzed for their metal contents and estimated daily intakes of these elements were determined. Seventeen brands (three samples per brand) of infant formula samples were analyzed for various essential (Ca, Co, Cu, Cr, Fe, Mg, Mn, Mo, Na, and Zn) and non-essential (Ag, Al, As, Ba, Be, Cd, Hg, Ni, Pb, Sb, Sn, Sr, Ti, Tl, U, and V) elements. Known weights and aliquots of the dry, powdered and liquid infant milk, respectively, were digested on the Ethos Plus microwave labstation. Digests were then analyzed with Perkin-Elmer DV 3300 inductively coupled plasma–optical emission spectrometer (ICP–OES). The observed values of SRM 8435 (Whole Milk Powder) analyzed using the same procedure were in agreement with the NIST certified values. The mean concentrations of the elements in milk-based and soy-based formulas, estimated mean daily intakes through infant formulas, and analysis of variances (ANOVA) across infant formula brands are presented. The results suggest that soy-based powder infant formulas generally had higher element levels than milk-based powder formulations, irrespective of source. The European Union (EU) drinking water maximum admissible concentrations for aluminium and barium and the US EPA standard for thallium were violated in some infant formula brands. Cadmium, lead, nickel and chromium were below their respective limits in drinking water and, also, the estimated daily intakes of Pb and Cd from infant formula were below the FAO/WHO Joint Expert Committee on Food Additives recommended provisional tolerable weekly intakes (PTWI) of 25 and 70 μg/kg body weight, respectively. Some brands had low nutritional contents when compared with the recommended dietary allowances (RDA) and dietary reference intakes (DRI) for use in North America. Only brands 7–9 and 12 (UK), and brands 13, 16 and 17 (USA) met the DRI for zinc. The daily intakes of iron (5.03 mg/day) from brand 2 (UK) and magnesium (23.9 mg/day) from brand 10 (UK) were below their respective recommended intake values. However, all the brands met the calcium DRI value of 210 mg/day.