Construction And Application Of Early Warning System For Dynamic Health Risk Assessment Of Soil Pollution In Construction Land Based On PBTK Model

Objective:With the emphasis on environmental preservation in China,the industrial structure has been continuously adjusted and highly polluting factories and enterprises in cities were closed or relocated one after another,and most of the remaining lands were polluted to different degrees.This is a critical concern for the environmental management of contaminated lands which is how to assess the health risks of construction lands scientifically,and on this basis propose an early warning system to avoid health risks,make scientific estimates of the possibility of environmental pollutants causing health damage to the population and their magnitude,strengthen health risk management and make reasonable recommendations for the use of the remaining construction lands.Methods:1.Based on the Browser/Server（B/S）architecture,we created the early warning system.My SQL was used to create the system’s spatial database,Java was used as the background technical support to realize interaction with the database,and Java Script was used to realize interaction between the front-end and back-end page data of the system.To create the platform layer and realize the algorithms such as spatial analysis,quantitative analysis,prediction,and early warning in the algorithm logic layer,we used Leaflet,Spring Boot micro-application architecture,Aviator algorithm expression engine,and computational model library.The User Interface（UI）was designed and created with Hyper Text Markup Language 5.0（HTML5）.2.We investigated a land that had stopped producing rare earths and selected 49soil sites and 9 groundwater sites.According to the method specified in the guidelines,the concentrations of lead（Pb）,cadmium（Cd）,mercury（Hg）and arsenic（As）in soil and groundwater samples were detected and statistically described.The inverse distance interpolation method was used to analyze the spatial distribution of heavy metal concentration.Taking the background value of soil environment in Ganzhou as the evaluation basis and four kinds of heavy metals as evaluation factors,single factor pollution index and Nemero pollution index were used to evaluate the environmental quality of soil and groundwater in the study area.Assess the potential health risks of the human body according to the model recommended in the guidelines.The spatial multi-criteria decision-making theory is introduced,the fuzzy method is used to solve the problem of dimensional differences among different indicators,the analytic hierarchy process is used to define the weights of each index,and the results are integrated by the ordered weighted average method.a joint evaluation model of soil environmental quality based on human health was established.Physiologically-Based Toxicokinetic（PBTK）model was used to simulate the absorption,distribution,and metabolism of pollutants in the study area,and the internal exposure dose was evaluated.3.We carried out a cross-sectional study in Liaoning Province,namely,workers from a molybdenum mine,magnesium mine,gold mine,iron and steel smelter and glass factory.We measured the concentration of 19 metals in workers’urine to evaluate metal exposure.The 19 metals are beryllium（Be）,aluminum（Al）,vanadium（V）,chromium（Cr）,manganese（Mn）,iron（Fe）,cobalt（Co）,nickel（Ni）,copper（Cu）,zinc（Zn）;As;selenium（Se）;strontium（Sr）;molybdenum（Mo）;Cd;Pb;cesium（Cs）;barium（Ba）;uranium（U）.We used Mahalanobis distance to exclude abnormal values,and compared the differences of continuous or discrete variables between normal blood pressure group and hypertension group.Logistic regression model was constructed to explore the relationship between urinary metal concentration and hypertension prevalence rate after controlling confounding variables,and the dose-response relationship between urinary metal concentration and hypertension prevalence rate was evaluated by Restricted Cubic Spline（RCS）regression.The mixed variables are controlled by robust inverse processing probability weighting method,and the Markov Chain Monte Carlo（MCMC）simulation method based on Bayesian Benchmark Dose（BBMD）analysis system is used to calculate the Benchmark Dose（BMD）and the lower bound of statistical confidence interval（BMDL）and probability Reference Dose（Rf D）of urinary metal in patients with hypertension when the Benchmark Response（BMR）was 5%and 10%,respectively.Results:1.According to the system requirements and system architecture,the functional modules of the system are mainly composed of two modules,namely the system background management and the dynamic health risk assessment and early warning of soil contamination on construction land.The back-end management module includes user information management,menu resource management,and data dictionary management.The early warning module for dynamic health risk assessment of soil contamination on construction land includes land project management,exposure pathway management,land parameter management,calculation model management,base layer control,health risk assessment,prediction,and early warning analysis,and PBTK analysis.2.Based on the actual needs of land risk management work and with reference to the relevant national environmental protection standards,we build data corresponding data service flow objects,including:land monitoring data upload,data restructuring and distribution server side,and data processing and analysis results display side.Through powerful information processing functions,risk control values and screening values for different contaminated lands are calculated,so that all queries and analysis results can be displayed visually and vividly in maps,text,charts,and other visualisations,facilitating users to carry out health risk assessment and early warning for multiple lands,multiple soil layers and multiple pollutants under different exposure scenarios.3.We have developed the PBTK model,a dynamic health risk assessment and early warning system for soil contamination on construction lands,and established a dynamic assessment system that effectively links key data such as contaminant source releases,environmental concentrations,target exposure doses and effect thresholds,which enables the simulation of changes in exposure marker concentrations in body tissues and blood over time and whole-body marker enrichment levels in different populations after contaminant exposure.4.The average concentrations of all four heavy elements in the rare earth land we investigated were below the screening values of class I sites for soil contamination of development land in China;of these,only the average concentration of Cd exceeded the background value for Jiangxi Province,which was 1.81 folds higher than the background value.Except for As,the maximum values of the other three hazardous elements in the soil exceeded the background values,with the maximum values of Pb,Cd,and Hg being 4.64,9.81,and 5.11 folds the background values,respectively.The coefficients of variation of each heavy metal in soil ranged from 54.50%to 131.56%,all of which were strong or unusually strong variations;compared with soil,the coefficients of variation of each heavy metal in groundwater were low and their concentrations were less heterogeneous.The results of the single factor index method indicate that the land soils are mainly at clean to moderate contamination levels.According to the classification of the Nemerow index,the percentages of clean,light,moderate,and heavily polluted sites are 51.0%,4.1%,8.2%,and 36.7%respectively,with the heavily polluted sites mainly located in the southwest and southeast areas of the site.The soil quality of the land has obvious spatial distribution characteristics.5.We assessed the carcinogenic and non-carcinogenic risks caused by the four heavy metals in the study area for different exposure pathways and found that drinking groundwater and oral ingestion of soil particulate matter were the most significant exposure pathways to soil heavy metals for potentially sensitive receptors at the land.Of the total carcinogenic risk due to soil pathway exposure,the probability of an acceptable risk was 12.2%and the probability of an unacceptable risk was87.8%;among the hazard quotients,the probability of insignificant human health effects due to soil heavy metals was 89.8%.The total carcinogenic risk due to groundwater pathway exposure was unacceptable;the human health effects of groundwater heavy metals were all acceptable in the hazard quotient.The results of the geostatistical modelling showed that the total carcinogenic risk of soil contaminants in the area was mainly distributed in a patchy pattern,with hotspots mainly concentrated in the central and central-northeastern part of the land;the spatial distribution of the total hazard quotient was similar to the total carcinogenic risk.The spatial distribution of the total carcinogenic risk of groundwater contaminants was similar to the spatial distribution of the total hazard quotient,with the high values mainly concentrated in the southwest of the land.6.The study on the relationship between heavy metal exposure and the risk of developing hypertension in an occupational population found higher concentrations of Co and Zn in urine samples from hypertensive patients compared to non-hypertensive participants（P<0.05）.Spearman’s rank correlation analysis showed that most metals were significantly correlated with each other,with Spearman’s correlation coefficients ranging from weak（r=0.02）to strong（r=0.96）.After correction for confounding variables,urinary Co showed a dose-response relationship with an increased prevalence of hypertension(P_trend<0.05).Compared to the first quartile group,the prevalence of hypertension was 2.361 folds higher（95%CI:1.092-5.105）in study subjects with urinary Co concentrations in the highest quartile group.The results of the RCS model showed that the dose-response relationship between urinary Co concentration and risk of hypertension was linear with a monotonically increasing trend（P for non-linearity=0.418）.The BMD and BMDL of urinary Co causing hypertension in the 5%population were 2.42μg/L and 0.72μg/L,respectively;the BMD and BMDL of urinary Co causing hypertension in the 10%population were4.34μg/L and 1.48μg/L,respectively.The Rf D of urinary Co causing hypertension in the 5%population was 0.33μg/L;the Rf D of urinary Co causing hypertension in the10%population was 0.66μg/L.Conclusion:1.A dynamic health risk assessment and early warning system for soil contamination on construction sites have been developed,which incorporates site project management,real-time data uploading,health risk assessment,and warning dissemination functionalities.In comparison to traditional models,this system is based on the PBTK model and allows users to customize the assessment and warning features based on various aspects related to health risk assessment on construction land.This customization capability meets the users’demands for rapid data processing and efficient utilization of data service flows.2.The concentrations of Pb,Cd,Hg,and As in the soil at the research site exceeded the background values for soils in Ganzhou City but did not exceed the screening values specified for construction sites.The southwestern region of the site（waste repository and wastewater treatment pond）and the southeastern region（abandoned rare earth mining area）exhibited severe contamination,while characteristic pollutants in groundwater were found to be in a relatively good state.The results of the health risk assessment indicated a relatively high carcinogenic risk to human health,emphasizing the need to consider the potential health risks associated with residents’exposure to heavy metals in the soil.The hotspots were primarily concentrated in the central part of the site（extraction workshop,settling workshop）,the northeastern part of the central region（finished product warehouse）,and the southwestern region（waste repository,wastewater treatment pond）.Based on a soil environmental quality joint evaluation model utilizing spatial multicriteria decision-making theory,the overall quality of the soil environment at the site exhibited distinct spatial distribution characteristics,with highly polluted areas primarily located in the central part of the site（extraction workshop,settling workshop）,the northeastern part of the central region（finished product warehouse）,the southwestern region（waste repository,wastewater treatment station）,and the southeastern region（abandoned rare earth mining area）.Through the independently developed dynamic health risk assessment and early warning system for soil contamination on construction sites,it was discovered that the Pb concentration in venous blood exhibited an increasing trend with age during the entire exposure lifespan,followed by a decline,while the Cd,Hg,and As concentrations showed a continuous increase with age.3.Cobalt exposure at occupational environmental levels may be associated with an increased risk of hypertension.BBMD modeling results indicated that the urinary cobalt BMD and BMDL levels causing hypertension in 5%of the occupational population were 2.42μg/L and 0.72μg/L,respectively,while the corresponding levels causing hypertension in 10%of the population were 4.34μg/L and 1.48μg/L,respectively.The Rf D for urinary cobalt causing hypertension in 5%of the population was 0.33μg/L,and for causing hypertension in 10%of the population,it was 0.66μg/L.