| ObjectiveAccording to a large number of test data on the concentration of lead(Pb) and cadmium(Cd) in water, soil, food and vegetables, the environmental exposure of children was determined, and the situation of children’s growth was evaluated through on-site investigation and laboratory tests. Finally, the influence of Pb, Cd pollution in Shaying river was explored on children’s health, and it will provide a scientific data for assessment of the polluted status of the Shaying River and children’s health protection.Methods1Polluted area and control area were selected randomly from the Shaying riverbed within5km and20km away. A primary school was selected randomly from each of the two villages and then the research objects were recruited from3to5grades using the cluster sampling method.2The river and drinking water, soil, food, vegetable samples were collected in the dry season and wet period, respectively. The content of Pb, Cd in environmental samples were determinated by direct flame atomic absorption spectrophotometry. According to test results, the levels of Pb, Cd in Shaying river were evaluated, and contents of Pb, Cd in various environmental media were compared with two areas.3The basic situation of children were surveyed by a questionnaire. The determination of children’s height, weight, chest circumference, lung capacity were accordance with the2005National Student Physical Health Survey program. Children’s IQ were measured using the combined Raven test. The results were used to compare the differences of IQ and children’s physical development indicators of two areas, respectively and evaluate the influences of Pb, Cd in Shaying river on children’s physical growth and intelligence.4The concentrations of Pb, Cd in children’s blood were measured by cyclic voltammetry, TSH, FT4and FT3were assayed by chemiluminescence method, and GH, GHBP, IGF-1and IGFBP-3were determined by enzyme-linked immunosorbent assay. The measured results were used to evaluate the influences of Pb, Cd pollution in Shaying river on children’s serum hormone.5The database were established using Epidata3.0software and the data were doubled enter into the database by different people. All the data were analyzed using SPSS12.0software. Kolmogorov-Smirnov test and Levene test were used to inspect the normality and homogeneity of variance of all data. According to data characteristics, analysis of variance, two independent samples t test and χ2test, Pearson correlation analysis and multiple linear regression analysis were used to analyze the results (significance level a=0.05).Rusults1According to the Standard of National Surface Water Quality (GB3838-2002), the concentrations of Pb in the wet and dry seasons were more than class IV, and Cd were exceeding class Ⅴ. There were no significant differences of Pb and Cd in each section of the wet and dry seasons (P>0.05).2Compared with the control area, the concentrations of Pb, Cd were significantly lower than in contaminated area (P<0.05). In accordance with national standards, Pb in control area were not excessive, but in polluted area were exceeded the state standards. The concentration of Cd in various environmental media in the control area were not exceeded, but the contaminated area were exceeding the corresponding standard.3The distribution of children’s age and gender were no significant difference in the two districts (P>0.05). Children’s blood lead and blood cadmium levels were significantly higher in contaminated area(P<0.05), and the concentrations of Pb, Cd were increased with age. Pearson correlation analysis showed that there were significantly correlation between children’s blood lead, cadmium and age (r=0.413, P<0.001; r=0.402, P<0.001).4There were no significant differences of children’s physical development indicators in the two areas(P>0.05), and among the different blood lead groups (P>0.05). The lung capacity of children whose blood Cd were more than5μg/L were significantly lower than the children who have normal blood cadmium (P<0.05), but the other indicators were no significant differences among the different blood cadmium groups(P>0.05). After correction for potential confounding factors, blood lead and cadmium levels were not the main factors to influence the physical development indicators (P>0.05). The growth-related hormones such as GH, IGF-1and IGFBP-3were significantly lower in children who were living in contaminated area(P<0.05), but the GHBP was no significant difference (P>0.05).5Compared with the control area, children’s IQ was significantly lower in the contaminated area(P<0.05), and there were significant differences of children’s IQ among the different blood lead, cadmium groups (P<0.05). There was a significant negative correlation between blood lead, cadmium and children’s IQ (r=-0.55, P<0.001, r=-0.439, P<0.001), and the correlation was still presence after correction for confounding factors (β=-0.293, P<0.05, β=-0.443, P<0.05). The intelligence related hormones such as FT4were significantly higher in children who were living in contaminated area (P<0.05), but the FT3were significantly lower (P<0.05). The TSH was no significant difference between the two areas(P>0.05).Conclusion1The pollution of Pb and Cd in Shaying river were serious, so that the contents of Pb, Cd in the living environment of the surrounding residents (such as drinking water, soil, grain, vegetables, etc.) were exceeded the standard. And they have entered the children’s body, so that the children’s blood lead and blood cadmium levels were increased with age.2The exposure of Pb, Cd had interfered with the levels of children’s thyroid hormone, and affected children’s intelligence. Meanwhile, they had also affected the levels of growth-related hormones such as GH, GHBP, IGF-1to a certain extent, but the impacts on physical development were not significant. |
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