| BackgroundLead, without any physical function to the organism, is toxic to several body systems and organs. However, because lead and lead compounds are widespread in the environment, it is inevitable that people expose to lead to some extent. The effect of lead on the nervous system is clearly manifested in the lower intelligence and neural behavior abnormalities. Besides, exposure to Lead is also related to high blood pressure and adverse pregnancy outcome, but the correlation is not uncertainty, due to the conclusion inconformity of researches.Materials show that there are only about a quarter lead having been recycled every year, and most of the rest are discharged into environment in the shape of waste gas, waste water and waste residue, and cause lead pollution in the atmosphere, water and soil by migration and transfer in ambient mediums. But along with the industrialization, lead output and consumption is still increasing in china. Then, lead pollution to the environment is more severe. Lead pollution has caused great economic losses.Lead pollution, because of health damage, has been a significant social problems evolved into the people’s livelihood, social stability and national physical quality. It will take a lot of funds to control and manage the lead pollution. Combined with national conditions, it is difficult to eradicate the lead pollution. So we need to take account of the source control, determine the priority managed object and managed level by health risk classification, develop management of environmental lead damage and intervention of population heath effect, obtain maximum social and environmental benefits, and protect public health.But the research of environmental health risk classification technology in china is weak, and the index system, which is included in the existing environmental health risk classification, is made up of by the index of risk source and exposure, excluding the index of human susceptibility. We should bring the index of human susceptibility into the model of environment health risk classification, to evaluate comprehensively risk of the environmental pollutants to human health. Therefore, the purpose of this study was to evaluate indexes of the lead health effects, and judge whether it can be used in lead pollution environment health risk classification model.Objective1. To evaluate the correlation between lead exposure and hypertension rate and the correlation of lead exposure with rate of adverse pregnancy outcomes.2. Evaluate the applicability of hypertension rate and the rate of adverse pregnancy outcomes in the model of lead pollution environment health risk zoning and classification.MethodsIn this paper, Meta-analysis is used to analyze the relation between high blood pressure and lead exposure and also to analyze the relation between lead exposure and adverse pregnancy outcomes. Then, the paper either evaluates the applicability of hypertension rate and rate of adverse pregnancy outcomes in the model of lead pollution environment health risk zoning and classification, according to the selection principle on the index of environmental health risk classification model.Firstly, the secondary researches are retrieved in Cochrane Library and there is no any related research found. So primary researches are searched in the primary resources. And according to the abstract, the irrelevant literatures, including researches about case reports, mechanistic investigation and animal experiment, are eliminated. Then, through the various methods, obtain full text of literatures, and read the entire articles. The second screening is carried out according to the standard of inclusion and exclusion. The rest literature after second screening, will be analyzed with Meta-analysis. In this paper, The Downs and Black lists is used to evaluate the quality of literatures and EpiData3.1software is used to collect the information of literatures. The extraction and inputs of the information are done by two people. Because the data of hypertension literature is numerical variable, the effect value is SMD; While the data of adverse pregnancy outcomes is binary variable, the effect value is OR. Finally, the effect value, the homogeneity test (Q test) and integrated analysis for the abstracted data of the eligible studies was conducted by using SPSS18.0Statistic Software, combined with the material type.On the principle of the index selection, this paper discusses the applicability of hypertension rate and the rate of adverse pregnancy outcomes used in the model of lead pollution environment health risk zoning and classification, on scientificity and manipuility. The scientificity is reflected from the positive rate of original research results, the positive rate of effect value results and the integrated effect value; while the manipuility is reflected in approach of achieving and Efficiency.Results1. Characteristics of the original researchThere are8original research papers were included in the hypertension project, including3Chinese papers and5English; the results of these studies are positive, showing there is a correlation between blood lead and hypertension. The score of quality is22to27, and the quality is good. In the project of adverse pregnancy outcome, there are7papers,4Chinese and3English; there are3articles for negative results,4for positive; the results of original research can’t determine whether there is a correlation between blood lead and adverse pregnancy outcome, so Meta-analysis is necessary. The score of quality is23to27, and the research quality is relatively reliable.2. Results of the Meta-analysisIn the hypertension project, there is1research in which95%confidence interval of the effect value (SMD) contains0, showing there is no relation between blood lead and hypertension. And the homogeneity test shows a statistical significance (Q=755.94, P<0.001), So the random effect model is used in the integrated analysis. The integrated effect value (SMD) is1.46(95%CI:-3.52-6.44),95%confidence interval contains0, showing there is no difference in blood lead level between2group. So Meta-analysis reveal there is no relation between blood lead and hypertension.In the project of adverse pregnancy outcome, there are3researches in which95%confidence interval of the effect value (OR) contains1, showing there are no relation between blood lead and adverse pregnancy outcome. And the homogeneity test shows a statistical significance (Q=1039.09, P<0.001), So the random effect model is used in the integrated analysis. The integrated effect value (OR) is2.48,95%CI:1.09-5.66.95%confidence interval doesn’t contain1, so Meta-analysis show there is relation between blood lead and adverse pregnancy outcome.3. The applied evaluation of indexThe evaluation of scientificity display that:The positive rate of the hypertension research, either for the original research or after integrated analysis, is higher than research of adverse pregnancy outcome. For the original research, The positive rate of hypertension research is100%, the research of adverse pregnancy outcome is57.14%; After integrated analysis, The positive rate of hypertension research is87.5%, the research of adverse pregnancy outcome is57.14%. The95%CI of integrated effect value (SMD) in hypertension research contains0, hinting non-correlation. The95%CI of integrated effect value (OR) in research of adverse pregnancy outcome does not contain1, hinting correlation. The evaluation of manipuility shows both of them can collected from existing materials and don’t need extra costs, that is both of them in manipuility are good.ConclusionLead exposure is related to adverse pregnancy outcomes and the rate of adverse pregnancy outcomes can be used as an indicator in the model of lead pollution environment health risk classification. Further research is needed to be carried out to judge whether the hypertension rate can be used in the model. |
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