Levels of toxic and essential elements found in the whole blood of 1110 children were analyzed using an atomic absorption spectrometer. Distributions and correlations of trace elements in different age groups were analyzed and compared.
The overall mean blood lead (Pb) and cadmium (Cd) levels (49.42 ¡À 20.16 and 1.47 ¡À 1.08 ¦Ìg/L, respectively) were relatively stable among different age groups. The prevalence of Pb and Cd intoxication in all children was 1.4 % and 0.4 % , respectively. Calcium (Ca) levels decreased gradually with age, with an overall concentration of 1.82 ¡À 0.15 mmol/L. Whole levels of copper (Cu) and magnesium (Mg) were 17.79 ¡À 4.22 ¦Ìmol/L and 1.52 ¡À 0.14 mmol/L, respectively. While 7.6 % of all children showed Cu levels below the normal threshold, the levels of Mg were stable in different age groups. Though the overall mean blood zinc (Zn) and iron (Fe) concentrations (59.59 ¡À 15.15 ¦Ìmol/L and 7.39 ¡À 0.74 mmol/L, respectively) gradually increased with age and the overall deficiency levels (59.8 % and 59.5 % , respectively) decreased with age, Zn and Fe deficiencies were still very common. Significant positive correlations were found when comparing Cu to Zn, Ca, Mg, and Fe; Zn to Mg and Fe; and Mg to Ca and Fe. Additionally, minor positive correlations were found when comparing Pb to Zn and Fe.
The degree of Pb and Cd intoxication in all the children studied was low; however, Pb and Cd exposure was still evident. The importance of Ca deficiency and supplementation is well recognized, but the severity of Fe and Zn deficiency is not as well documented.