Towards bio monitoring of toxic (lead) and essential elements in whole blood from 1-to72-month old children: a cross-sectional study

Objectives: Minerals such as zinc, copper, selenium, calcium, and magnesium are essential for normal human development and functioning of the body. They have been found to play important roles in immuno-physiologic functions. The study is to evaluate the distribution and correlation of nonessential (lead) and essential elements in whole blood from 1- to 72-month old children. Methods: The cross-sectional study was performed in 1551 children. Six element concentrations, including copper (Cu), zinc (Zn), calcium (Ca), magnesium (Mg), iron (Fe) and lead (Pb) in the blood were determined by atomic absorption spectrometry. Distributions and correlations of trace elements in different age groups were analyzed and compared. A Pearson correlation controlled for age and gender was used to assess the relationship of non essential (lead) and essential elements. Results: Levels of copper and magnesium were 18.09 +/- 4.42 mu mol/L and 1.42 +/- 0.12 mmol/L, respectively. 6.04% of all children showed copper levels below the normal threshold, the levels of Magnesium were stable in different age groups. Though the overall mean blood zinc and iron concentrations (61.19 +/- 11.30 mu mol/L and 8.24 +/- 0.59 mmol/L, respectively) gradually increased with age and the overall deficiency levels (24.1% and 36.0%, respectively) decreased with age, zinc and iron deficiencies were still very stable. Controlling for gender and age, significant positive correlations were found when comparing copper to zinc, calcium, magnesium, and iron((r = 0.333, 0.241, 0.417, 0.314, p < 0.01); zinc to magnesium and iron (r = 0.440, 0.497p < 0.01); and magnesium to Calcium and iron(r = 0.349, 0.645, p < 0.01). The overall mean blood lead levels (41.16 +/- 16.10) were relatively unstable among different age groups. The prevalence of lead intoxication in all children was 1.3%. Calcium levels decreased gradually with age, with an overall concentration of 1.78 +/- 0.13 mmol/L. Conclusion: Significant negative correlations were also noted between Pb and Zn, Fe (r = -0.179, -0.124. p < 0.01). The importance of calcium deficiency and supplementation is well realized, but the severity of iron and zinc deficiency is not well recorded. The degree of lead intoxication in all the children studied was low; The established reference intervals for Cu, Zn, Ca and Mg provide an important guidance for the reasonable supplementation of essential elements during different age groups.