| Human body always obtains various elements from geographical environment through the diet. The kinds and contents of elements are related to the composition in earth surface and dietary intake. Lacks a few microelements can lead to many kinds of disease. The gap between requirements and poisoning dose is relative small; so excessive intake of essential trace elements can also cause toxicity damage. The childhood is the critical period of physical and intellectual development, with the characteristics of quick development, sharp metabolism, imperfect balance mechanism (absorption, utilization, excretion, storage, and so on), and a large demand of nutrition, a low sensitivity to the deficiency of macro and minor elements. Therefore, trace elements show a close relationship with the children's nutrition, growing development, defense mechanisms, intellectual level and appetite. The trace elements effect on physical and mental development has attracted a great deal of international attention in recent years. Early diagnosis of trace elements deficiency, mastery of the futures and laws are very important for guarantee the healthy growth of children and related disease prevention.ObjectivesTo explore the nutrition level of trace elements and their effects on growth development, the trace elements in blood of children aged 2～5 in Changchun will be detected, for the purpose of providing the scientific basis for child health care in the future.Methods400 children aged 2～5 was randomly selected in six districts of Changchun, who is relative health without important organs damaged and acute disease attacked within two weeks; at the same time, 404 children with the same standard was adopted in four countries. The growth and development indexes such as body and sitting height, weight, chest and head circumference were detected; meanwhile venous blood was collected on the elbow to examine the contents of copper, magnesium, zinc and calcium, iron, lead. SPSS 13.0 software was used for data analysis. Differences among categorical variable data were compared by chi-square statistics, while in numerical variable data t test or rank sum test was used.Results804 children were investigated in the study, with the proper ratio of male to female. No significant difference in age and sex was found between urban and suburb, with a relative balance. The average concentrations of copper, calcium, iron and lead were in normal range, but the content of zinc both in urban and suburb was less than lower limit (72μmol/L), with the concentration of 64.0μmol/L and 66.3μmol/L respectively. Compare to suburb, the copper content in the urban was higher (P=0.0015); but the zinc content was lower (P=0.0155). In the urban, the concentration of zinc and lead was lower the reference range, and no significant difference was found six elements (copper, magnesium, zinc and calcium, iron, lead) between male and female (P>0.05); as well, the results were also showed in the suburb. In the urban, the content of zinc among several age groups showed a significant difference; the median content of zinc in the age group of 2～, 3～, 4～, 5～was 59.0μmol/L, 55.5μmol/L, 63.5μmol/L and 72.0μmol/L respectively. Thus, in the urban, older children showed high zinc content, while the younger behaved zinc deficiency obviously, but in partial children the content still in the normal range. In the suburb, no significant difference of zinc contents was found among age groups; the median content of zinc in the age group of 2～, 3～, 4～, 5～was 60.1μmol/L, 65.3μmol/L, 66.4μmol/L and 73.7μmol/L respectively; the tendency of higher content in older children was also found in the suburb. As for copper, magnesium, zinc and calcium and iron, the contents were all in the normal range no matter urban or suburb; significant differences among age groups were failed to be found. All the content of lead didn't exceed the upper limit; and the lead content in 5～age group was significantly higher than other age groups (P<0.05).The average value of body height, weight, chest and head circumference, sitting height in the urban was 102.9cm, 17.6kg, 49.3cm, 52.7cm, 53.7cm respectively; correspondingly the value in the suburb was 100.3cm, 16.5±2.8kg, 48.9cm, 51.4cm, 52.9cm. All of the above indexes in the urban were higher than in the suburb (P <0.001). In the urban, the value of body height, weight, head circumference and sitting height in male was higher than in female (P<0.05). In the suburb, males showed a higher value of head circumference and sitting height than females (P<0.05), but there was no significant difference in body height, weight, chest circumference. The five growth development indexes were different among age group, with age dependent, which showed uninterrupted growth development.The correlation between elements (zinc, magnesium and lead) and all of the growth development indexes was significant; iron was only related with body height, head circumference and sitting height. However, copper and calcium showed no significant relationship with the five growth development indexes.Conclusions1. Both in urban and suburb, the zinc content of children was less than lower limit (72μmol/L), which suggested that the deficiency of zinc was a common phenomena; The average concentration of copper, calcium, magnesium, iron and lead was in normal range.2. No matter urban or suburb, there was no significant difference in all trace elements between male and female.3. In the urban, the zinc contents among several age groups showed a significant difference, and older children showed higher zinc content than the younger. In the suburb, the zinc and iron contents showed a significant difference among several age groups, and the contents of two elements increased with age increasing. Lead was both found in urban and suburb, increasing with the age.4. In the urban, males showed a higher value of body height, weight, head circumference and sitting height than females, but there was no significant difference in chest circumference. In the suburb, males showed a higher value of head circumference and sitting height than females, but there was no significant difference in body height, weight, chest circumference. The five growth development indexes were different among age group, with age dependent, which showed uninterrupted growth development.5. Both in urban and suburb, copper and calcium showed no significant relationship with the five growth development indexes .In the suburb, between elements (magnesium and iron) and all of the growth development indexes, the correlation was positive.
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