Objectives  To evaluate the distributions and correlations among nonessential (lead) and 5 essential elements in whole blood from 0-7 years old children in Longhua District, Shenzhen.

Methods  A total of 3 102 healthy children who underwent physical examination at Children's Health Checkup Center in Longhua District from January 2017 to September 2018 were included. Atomic absorption spectrometry was used to determine the level of 6 nonessential or essential elements such as calcium (Ca), zinc (Zn), copper (Cu), magnesium (Mg), iron (Fe) and lead (Pb) with children's whole blood. Distributions of trace elements in different developmental stages were analyzed and compared. Pearson correlation was used to assess the relationships of Pb with 5 essential elements.

Results  The mean level of Pb was (40.16±16.10) μg/L, and the prevalence of plumbism in all children was 0.55% (17/3 102). Compared with the infant group (43.17±15.43) μg/L and the young children group (40.51±15.07) μg/L, the Pb level in the preschool group (32.51±14.20) μg/L was lower (F=13.86, P＜0.01). 6.45% (200/3 102), 22.82% (708/3 102), 6.32% (196/3 102) and 35.62% (1 105/3 102) of children had Cu, Zn, Ca, and Fe levels below the normal threshold. With the increase of age, the concentrations of Cu, Zn and Fe gradually increased, while the level of Ca gradually decreased. Pearson correlation analysis showed that there were significant positive correlations between Zn and Mg, Fe (r values were 0.440 and 0.499, respectively, P＜0.01), Cu and Zn, Ca, Mg, Fe (r values were 0.335, 0.242, 0.419, 0.316, respectively, P＜0.01), Ca and Mg (r=0.349, P＜0.01), Mg and Fe (r=0.645, P＜0.01), and there is a significant negative correlation between Pb and Zn, Fe (r values were -0.279 and -0.224, respectively, P＜0.05).

Conclusions  Although the prevalence of plumbism among children was relatively low with the prevention and control measures in recent years in Longhua District, Shenzhen, the overall blood Pb levels in this population was not such optimistic. Results showed that blood Pb levels can be influenced by the status of some essential trace metals in children, and supplement of nutritional elements may help to reduce the absorption of Pb.