| As the standards of environment and health have been officially brought into line with the national environmental protection system,and the concept of public health is gradually integrated into the environmental protection policy.This study was conducted in the typical non-ferrous metal mining area with a high risk of environmental and health in southern Hunan,which is known as the "World’s Nonferrous Metal Museum".Refer to the Site Contamination Risk Assessment Technology Guide HJ25.3-2014(C-RAG)procedure.This essay aims to assess the risk of cancer and non-carcinogenic health risks of lead,cadmium and arsenic heavy metals contaminating in soil and vegetables by using the health risk assessment.To provide base for the health and environmental protection department when they formulating the decision and management measures about the prevention and control of environmental based on protect people health.To make the measures aboutprevention and control the health damage or disease related to environmental factorsmore efficient.By comprehensively using the Meta-analysis,geographic information system,field investigation,laboratory testing and health risk,we have evaluated the heavy metal pollution in farmland soil and corresponding vegetables in the area,detected the heavy metal load in the blood and urine of school-age children under different soil pollution exposure,analyzed the statistical relationship between heavy metal pollution and the health of school-age children,established exposure conditions of children,in which lead,cadmium and arsenic were considered as major heavy metal pollutants,and we finally obtain the exposure parameters of local school-age children through data collection,field monitoring and exposure model simulation.Now,the main research contents and results are as follows.1.Study on pollution sources and main heavy metal pollutants’characteristics in the soil within the study area.Objectives To analyze from the aspects of spatial distribution of heavy metalpollution sources,the situation of environmental governance,the time variatious of heavy metal monitoring data in rivers,the basic condition of residents’ health and historical and typical heavy metal pollutant residues in soil,etc.Methods Through historical data collection before 2015 and field investigation,the pollution sources and sudden environmental incidents in the study area were collected and analyzed.Through the combination of systematic review and GIS analysis,the heavy metal contamination around the Dong River basin affected by tailings was analyzed.The characteristics of residents’ living behaviors were investigated on the spot.The incidence of chronic diseases was investigated by questionnaire,and the blood lead concentration was tested by sampling.Results The distribution map of GIS shows the heavy metals pollution of in the of agricultural soil along the D River in the study area was serious.From 2008 to 2015,the out-of-standard rate of Pd,Cd,and As at the Dong River section decreased year by year.Until 2015,except for one sampling point where As was slightly exceeded,the other four years’ monitoring data did not exceed the standard.The prevalence of chronic diseases in the investigated population(30.1%)was significantly higher than the prevalence of chronic diseases in rural residents aged 15 years and above in the national central region(23.15%).The average blood Pb concentration of children was 74.2μg/L,which was higher than the average level in Hunan Province.(Meta analysis of this article:the average value of blood Pb in children in Hunan Province was 66.95±27.93 μg/L).The GIS map shows the neighboring relationship between the pollution source and schools and residential areas.There is no grain planting in the area,and 90%of the vegetables consumed by the residents come from self-sufficient and self-sustaining vegetables grown in sporadic vegetable fields in the area,and they drink tap water.Conclusions(1)The main sources of pollution are the tailings and waste water produced during the mining process,the abandoned ore tailings after the renovation,and the sudden environmental events of the collapse of the tailings pond towards the East River and its banks;(2)Tail pollutants in sand reservoirs are characterized by Pd,Cd,As,Cu,Zn,etc.The soil in agricultural land is heavily polluted.The main pollutants are Pd,Cd,As,Cu and Zn.The GIS distribution shows that the pollution is close to the river channel;(3)Research area’s effect of regional pollution control is obvious.At present,there are no tailings and waste residues on river channels and riverbanks,and there is basically no out-of-standard phenomenon in river monitoring.(4)The study area is based on the exposed scene of sensitive land use.School-aged children are mainly exposed through soil and vegetable pathways,which might expose them to polluted areas for a long time and do harm to their health.Thus,it is necessary to carry out further studies about hazard effects,exposure assessment,and risk characterization.2.GIS-based analysis on heavy metal contamination of agricultural soils and vegetable impactObjectives On-site monitoring the heavy metal concentration of agricultural land and corresponding vegetables in the study area,and analyzing its pollution characteristics,which is to provide the environmental exposure parameters for further risk characterization and the scientific basis for local environmental management departments to formulate agricultural land pollution standards and policies and measures based on public health.Methods 16 agriculture soil samples and 129 vegetable samples from 9 types of corresponding soil were obtained from 16 sampling areas in the study area.Determination of 6 heavy metal concentrations of Pb,Cd,As,Zn,Cu,Cr in samples by ICP-MS.The ICP-MS describes the distribution of heavy metal concentrations in soil and vegetables,and introduces the concept of control values and geographic information systems.And it evaluates and correlates soil environmental quality and heavy metal pollution in vegetables.Vegetable contamination in soils with high pollution levels was significantly higher than that of soils with low pollution levels.Results The out-of-standard rate of 6 heavy metals in 16 agriculture soil samples was ranked as Cd(100%)>As(93.75%)>Pb(62.50)>Zn(43.75)>Cu(12.50)>Cr(0%).The average concentrations of heavy metals in As,Cd,and Pb all exceeded the background value and risk screening value of soil in Hunan Province.The pollution degree of 4 types of vegetables is ranked as follows:root vgetables>leafy vegetables>melons>beans and other types,and their average pollution index are 5.606、2.889、2.137 和 1.052 respectively.Different kinds of vegetables have different enrichment ability for various heavy metals.And the enrichment of As,Cd and Pb from leafy vegetables and root vegetables is higher than that of melons and beans and other vegetables.Conclusion The main heavy metals of agricultural land in the study area are As,Cd and Pb.In addition to the concenntration of individual elements contaminated by moderate pollution,others are at levels of severe pollution.Because of high concentrations of heavy metals in vegetables,there are high risks to the health of the residents.Apart from the small part of the agricultural soil in the region that can be safely used,most of them should be strictly controlled.3.Study on the load level of school-age children on heavy metal pollutants and its health effects in the area.Objectives To explore the dose-response relations between heavy metal pollution levels in residential areas as well as school-age children’s heavy metal load and health effects,and to confirm the damage done to school-age children’s health by the heavy metal pollution within the study area.To provide information on exposed populations for the next step in risk characterization studies,and to lay the ground work for the local environmental protection authorities to formulate benchmark values of environmental heavy metals based on school-age children’s health,and to provide evidence for the local health and sanitation authorities to carry out targeted prevention and control of local school-age children’s major health problems.Methods From March to August 2017,241 school-age children(123 males and 118 females,average 7.82±1.02 years old)from Grade 1 to Grade 3 in three primary schools underwent the Rutter Child Behavior Checklist(parents version)evaluation;the children’s IQ was evaluated using the fourth edition of the Webster Intelligence Scale for Children;the child’s growth and development indicators were measured on-site and urine and venous blood were collected.The differences and relations of health effects such as heavy metal load and growth,behavioral intelligence,and routine blood urine indexes among school-aged children were detected and analyzed in the soil from their environment of different heavy metal polluted categories.Results We recruited 241 children,of which 159 parents agreed to draw blood and collect urine samples of their children.And there are 70 children volunteered for intelligence tests.The children in the survey area had a geometric mean of blood lead concentration of 46.96μg、L.61.01%of children with blood lead concentration>50μg/L and 10.06%with blood lead>100μg/L.Children’s blood cadmium concentration(2.32±2.34),urinary cadmium concentration(1.20±1.02),urinary arsenic concentration(73.46±64.50)were significantly higher than the national average,and blood cadmium,urinary cadmium and renal function were negatively correlated.We divided the farmland soil in residential area according to the Nemero comprehensive pollution index.And we found that school-age children’s blood lead concentrations were significantly different in moderately contaminated areas(n=19,39.80±21.24 μg/L)and heavily contaminated areas(n=140,61.75±33.55 μg/L)(P<0.05).The concentration of lead in soil was associated with the incidence of high lead in children,and the concentration of soil cadmium was correlated with the urinary cadmium concentration in children and RBP concentration are related.The average IQ of participant children was 93.93±9.72,which was lower than the national average.The total IQ,perceptual reasoning index and working memory index of the group whose blood Pb levels≥ 50μg/L was significantly lower than those of blood Pb levels<50μg/L(P<0.05).The higher the levels of urinary Cr,urinary Mn and blood Mn were,the lower the scores of some indexes in IQ were(P<0.05).The blood levels of Cu were positively correlated with the working memory index,while the levels of urinary Cu and urinary As were negatively correlated with the processing speed index(P<0.05).The results of utter behavior scale showed that the positive rate of children with behavioral problems was 21.61 percent,and A behavior was the main one.Logistic regression analysis showed that the blood levels of Fe were an important indicator to reflect the behavioral problems of participant children(x2=9.698,P<0.05).Conclusions The concentrations of Pb,Cd,and As in children’s blood and urine in the study area were higher than those in the national or Hunan’s average level The loading level of Pb,Cd,As,and Mn in children’s body and the heavy metal contaminated soil types in the study area have varying degrees of impairment on the children’s verbal comprehension,working memory,processing speed and total IQ.It can be concluded that the low intelligence level of children around the mining area is related to the heavy metal pollution and that the children around the mining area are harmed by the heavy metal pollution,so it is necessary to carry out the next step of the health risk characterization on the long-term health effects of the pollution.4.Health risk assessment of school-age children exposed to lead,cadmium and arsenic contamination in soil/dust and vegetableObjectives:Apply non-carcinogenic risk models and carcinogenic models to evaluate the health risk of school-age children who were exposed to Pb,Cd and As in soil in the study area,thus provide scientific basis for hygiene and health department and environmental protection department to prevent children’s major diseases and to deal with environmental issues.Approaches:Different approaches used to obtain environmental data and exposure information data including questionnaires and measurement about the physical characteristics and diary of school-age children in the study area,domestic literature reviews,data collection and analysis,field monitoring and simulation prediction.Carcinogenic and non-carcinogenic risk assessments model and determining criteria recommended by UEPA were adopted to calculate and evaluate children’s carcinogenic and non-carcinogenic risk and risk quotient generated by soil Pb,Cd and As exposures respectively.Uncertainty and sensitivity analysis were performed using the Crystal Ball model and Monte Carlo simulation.Results:The ways of exposure to the contamination of Pb,Cd and As derived from soil for school-age children were determined,i.e,the school-age children are breathing,eating and touching these harmful elements from soil,dust and self-provied or self-supported vegetables.And there is a non-carcinogenic risk of eating and touching As from soil and dust.The risk rank of carcinogenesis through various pathways of soil and dust medias is As>Cd>Pb,except for the respiratory inhalation,the carcinogenic risk of As at P10 exceeds the UEPA-recommended minimum limit of 1.0×10-6 and the carcinogenic risk of Cd at P50 exceeds 1.0×10-6,Pb slightly exceeds the minimum limit at P90 by oral direct ingestion.No carcinogenic risk value exceeds UEPA-recommended upper limit of 1.0× 10-4.Conclusions:It is not yet considered that there is non-carcinogenic and carcinogenic risk of Pb,Cd and As in soil after being ingested through vegetable medium in the study area.The pollution of Pb,Cd and As in the soil of the study area from other means has posed certain threat to the health of local school-age children,the risk of which can be ordered as:As>Cd>Pb. |
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