Arsenic and fluoride co-enrichment of groundwater in the loess areas and associated human health risks:A case study of Dali County in the Guanzhong Basin

This study aims to reveal the occurrence and origin of typical groundwater with high arsenic and fluoride concentrations in the loess area of the Guanzhong Basin—a Neogene faulted basin.Key findings are as follows:(1)Groundwater samples with high arsenic and fluoride concentrations collected from the loess area and the terraces of the Weihe River accounted for 26%and 30%,respectively,of the total samples,with primary hydrochemical type identified as HCO_(3)-Na.The karst and sand areas exhibit relatively high groundwater quality,serving as preferred sources for water supply.It is recommended that local governments fully harness groundwater in these areas;(2)groundwater with high arsenic and fluoride concentrations in the loess area and the alluvial plain of rivers in Dali County is primarily distributed within the Guanzhong Basin,which represents the drainage zone of groundwater;(3)arsenic and fluoride in groundwater originate principally from natural and anthropogenic sources;(4)the human health risk assessments reveal that long-term intake of groundwater with high arsenic and fluoride concentrations pose cancer or non-cancer risks,which are more serious to kids compared to adults.This study provides a theoretical basis for the prevention and treatment of groundwater with high arsenic and fluoride concentrations in loess areas.

Future climate change decreases multi-pathway but increases respiratory human health risks of PAHs across China

Future climate change will affect the environmental fate of hydrophobic organic contaminants(HOCs)and associated human health risks,yet the extent of these effects remains unknown.Here,we couple a high-resolution environmental multimedia model with a bioaccumulation model to study the multimedia distribution of 16 priority polycyclic aromatic hydrocarbons(PAHs),a group of HOCs,and assess future PAH-related human health risks under varying climate change scenarios over China at a continental scale.After removing the effects of PAH emission changes,we find that the total PAH concentrations would decrease in the air,freshwater,sediment,soil,and organisms,while the high-molecular-weight PAH would increase in the air with climate warming from 1.5°C to 4°C.Consequently,the multi-pathway exposure human health risks predominately influenced by dietary ingestion are expected to decrease by 1.7%–20.5%,while the respiratory risks are projected to rise by 0.2%–5.8%in the future.However,the persistently high multi-pathway human health risks underscore the need for reducing future PAH emissions by 69%compared with 2009 levels in China.Our study demonstrates the urgency of limiting PAH emissions under future climate change for public health and highlights the importance of including the contribution of dietary ingestion in human health risk assessment.

A review of physicochemical and biological contaminants in drinking water and their impacts on human health

Clean drinking water is one of the United Nations Sustainable Development Goals.Despite significant progress in the water purification technology,many regions still lack access to clean water.This paper provides a review of selected water contaminants and their impacts on human health.The World Health Organization(WHO)guidelines and regional standards for key contaminants were used to characterise water quality in the European Union and UK.The concept of safe drinking water was explained based on the non-observed adverse effect level,threshold concentrations for toxic chemicals,and their total daily intake.Various techniques for monitoring water contaminants and the drinking water standards from five different countries,including the UK,USA,Canada,Pakistan and India,were compared to WHO recommended guidelines.The literature on actual water quality in these regions and its potential health impacts was also discussed.Finally,the role of public water suppliers in identifying and monitoring drinking water contaminants in selected developed countries was presented as a potential guideline for developing countries.This review emphasised the need for a comprehensive understanding of water quality and its impacts on human health to ensure access to clean drinking water worldwide.

Contamination and human health risk assessment of heavy metal(loid)s in topsoil and groundwater around mining and dressing factories in Chifeng,North China

Chifeng is a concentrated mining area for non-ferrous metal minerals,as well as a key prevention and control area for heavyduty enterprises.This situation necessitates an efective ecological and human health risk assessment of heavy metal(loid)s driven by the wide distribution of metal ore processing,mining,and smelting factories in Hexigten Banner and Bairin Left Banner.We conducted surveys to assess the levels of heavy metal(loid)s(Cr,As,Pb,Cd,and Hg)in the topsoil and groundwater of the areas.The results indicated that the concentrations of As,Cd,and Pb in partial soil samples exceeded the environmental quality standards of Grade II.Based on contamination assessments,such as geoaccumulation indices and pollution indices,we inferred that Cd,Pb,and As were primary pollutants in topsoil.Potential ecological risks when considered as part of the average risk indices(RI)are up to 1626.40 and 2818.76,respectively,in the two areas.Comparative analysis revealed that Cd posed a very high potential ecological risk,followed by As.Moreover,the evaluation showed that the three exposure pathways of carcinogenic and non-carcinogenic risk followed a descending order:inhalation>ingestion>dermal contact,except for Pb.Arsenic in topsoil posed a potential non-carcinogenic risk to human health,while there were no adverse efects of As in groundwater.In addition,the average total carcinogenic risk for As in the two areas,as well as the risk of Pb in the topsoil of Bairin Left Banner and all the fve heavy metal(loid)s in groundwater,exceeded human tolerance.Pb–Zn mines caused higher human health risks.In addition,the tandem contamination of heavy metal(loid)s in soil and groundwater was not obvious.This research study provides a basis for pollution remediation to control heavy industry-induced ecological and health risks of heavy metal(loid)s.

Eco-toxicity and health risk assessment of polycyclic aromatic hydrocarbons in surface sediments of Burullus Lake in Egypt

Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous environmental contaminants of growing concern due to their potential ecological and human health risks.This study presents a comprehensive assessment of PAHs contamination in the surface sediments of Burullus Lake,a vital and second largest delta lake in Egypt.The aim was to evaluate the eco-toxicity and potential health risks associated with the presence of these compounds.Surface seven sediment samples were collected from various drains in the southern part of Burullus Lake.Soxhlet extraction method was employed to extract PAHs(16PAHs)from the sediment sample.Analytically,target compounds were located using HPLC.The results showed that samples contained PAHs levels ranging from 0.038×10^(-6)to 0.459×10^(-6),which is considered heavily polluted by the European standard for PAHs pollution.Additionally,there was no apparent source of PAHs in the ElKhashah drain or the Brinbal Canal,as HPLC found none of the compounds.The most prevalent compound in sediment samples along the study area was fluoranthene.The diagnostic indices in the present study indicated that the hydrocarbons in the region originated from pyrolytic and man-made sources along the drains of Burullus Lake.The principal component analysis(PCA)and diagnostic ratios revealed that coal combustion and pyrolytic sources were responsible for the PAHs contamination in the surface sediments.The non-carcinogenic risk(HI),which is the product of the HQs for the adult and child populations,respectively,was calculated.HI values under 1,therefore,demonstrated that they had no carcinogenic effects on human health.TEQs and MEQs in the sediments of Burullus Lake do not have a cancer-causing impact on people.For the safety of nearby wildlife,aquatic life,and people,all activities that raise petroleum hydrocarbon levels in Burullus Lake must be adequately regulated and controlled.According to the ecological risk assessment,there is little chance that PAHs will be found in the sediments of Burullus Lake.This study underscores the urgent need for effective pollution control measures and regular monitoring of PAHs levels in Burullus Lake sediments to protect the aquatic ecosystem and public health.It also highlights the importance of considering eco-toxicity and human health risks in integrated risk assessments of PAHs-contaminated environments.

Current situation and human health risk assessment of fluoride enrichment in groundwater in the Loess Plateau:A case study of Dali County,Shaanxi Province,China

This study aims to investigate the mechanisms and health risks of fluoride enrichment in groundwater in the Loess Plateau,China.By taking Dali County,Shaanxi Province,China as an example,this study obtains the following results through field investigation and the analyses of water,soil,and crop samples.(1)The groundwater can be divided into two major types,namely the Quaternary pore-fissure water and Karst water.The Karst area and sandy area have high-quality groundwater and serve as the target areas for optional water supply.The groundwater in the study area is slightly alkaline and highly saline.Meanwhile,high-fluoride groundwater is mainly distributed in the loess and river alluvial plains in the depression area of the Guanzhong Basin and the discharge areas of the groundwater,with the highest fluoride concentration exceeding seven times the national standard.(2)Fluoride in groundwater mainly originates from a natural source and human activities.The natural source refers to the fluoride-bearing minerals in rocks and soil,and the fluoride from this source is mainly controlled by natural factors such as climate,geologic setting,pH,specific hydrochemical environment,ion exchange,and mineral saturation.Human activities in modern life can be further divided into industrial and agricultural sources primarily.(3)The health risks of fluoride contamination are very high in the Loess Plateau,especially for children compared to adults.Meanwhile,the risks of fluoride exposure through food intake are higher than those through drinking water intake.The authors suggest selecting target areas to improve water supply and ensure the safety of drinking water in the study area.Besides,it is necessary to plant crops with low fluoride content or cash crops and to conduct groundwater treatment to reduce the fluoride concentration in drinking water.These results will provide a theoretical basis for safe water supply in the faulted basin areas in the Loess Plateau.

Groundwater arsenic poisoning in a primary educational institution:health risks to school-going children

This study aimed to estimate arsenic(As)and iron(Fe)content in tubewell water(n=58)in primary educational institutions and subsequently assess the health risks to school-going children.Results described that the As concentration ranged between 0.002 and 0.994 mg L^(-1)with an average value of 0.044 mg L^(-1);which exceeded the World Health Organization(WHO)provisional guideline value of 0.01 mg L^(-1).Similarly,the Fe content varied from 0.05 to 10 mg L^(-1)averaging to 2.84 mg L^(-1).Samples of 55.17%contained a greater As concentration than0.01 mg L^(-1)and 18.97%greater than Bangladesh drinking water quality(BDWQ)standard of 0.05 mg L^(-1),respectively.Meanwhile,75.86%of samples contained a higher Fe concentration than the maximum Bangladesh permissible limit of 1 mg L^(-1).Health risk assessment indicated that girls are more vulnerable than boys are.The average hazard quotients(HQs)for As intake through drinking water were 6.01±17.85 and 7.41±22.03 for boys and girls,respectively,implying non-carcinogenic health risks to both genders.The HQs for Fe intake were less than threshold value of 1 indicating no health issues may arise from Fe intake alone.However,consumption of As and Fe may trigger health risks to students as indicated by the hazard index(HI),which was higher than 1.The average cancer risk(CR)values for both boys(0.0027±0.008)and girls(0.0033±0.0099)exceeded the threshold limit of 10-6-10-4,suggesting a possibility of lifetime cancer risks to the school-going children.Consequently,school authorities should find alternative ways to ensure safe drinking water for school-going children to avoid possible cancer and non-cancer health risks through consumption of As-poisoning water.

Human Health Risk Assessment Model of Organic Pollution in Groundwater:Shijiazhuang Industrial Zone

In this study, a risk-based management model is developed and applied to an industrial zone. The models proposed by the United States Environmental Protection Agency and Han Bing have been improved by adding a residual ratio of volatile organic compounds （VOC） after boiling and deleting the related parameters in half-life. Using this improved model, an integrated process was used to assess human health risk level in the study area. Compared with water quality analysis, the results highlight the importance of applying an integrated approach for decision making on risk levels and water protection. The results of this study demonstrated that： （1） Compared with these permissible level standards in China （GB 3838-2002） and National Primary Drinking Water Regulations of the United States, the residents＇ daily life had not been affected by the groundwater in this area （except for relative bad water quality of HB3-4 and HB3-6）; （2） The typical detected organic contaminants of all groundwater samples were chloroform, carbon tetrachloride, trichloroethylene and tetrachloroethene, and the pollution sources were mainly industrial sources by preliminary investigations; （3） As for groundwater, the non-carcinogenic risk values of all samples do not exceed the permissible level of 1.0 and the carcinogenic risk values are relatively lower than the permissible level of 1.00E-06 to 1.00E-04; （4） Drinking water pathway of trichloroethylene and tetrachloroethylene mainly contribute to increasing the health risk of residents＇ in study areas; （5） In terms of non-carcinogenic risk and carcinogenic risk, the health risk order for drinking water pathway and dermal contact pathway was： drinking water pathway 〉 dermal contact pathway.

Geochemical signatures and human health risk evaluation of rare earth elements in soils and plants of the northeastern Qinghai-Tibet Plateau,China

Information on rare earth elements(REEs)in soils and plants of the Qinghai-Tibet Plateau is very limited.Therefore,in this study,we performed field sampling to explore the geochemical signatures and human health risk of REEs in soils and plants of the northeastern Qinghai-Tibet Plateau,China.A total of 127 soil samples and 127 plant samples were collected from the northeastern Qinghai-Tibet Plateau to acquire the geochemical signatures and related human health risks of REEs.The mean total concentrations of REEs in soils and plants of the study area reached 178.55 and 10.06 mg/kg,respectively.The light REEs in soils and plants accounted for 76%and 77%of the total REEs,respectively.REEs showed significantly homogenous distribution in soils but inhomogeneous distribution in plants of the study area.Characteristic parameters indicated that light REEs were enriched and fractionated significantly,while heavy REEs were moderately fractionated in soils and plants.REEs in soils and plants showed significantly negative Europium anomaly.Cerium showed slightly positive anomaly in plants and slight anomaly in soils.The normalized distribution patterns of REEs were generally similar in the analyzed soils and the corresponding plants of the study area.The average bio-concentration factor of REEs ranged from 0.0478(Scandium)to 0.0604(Europium),confirming a small accumulation of REEs by plants.Health risks caused by REEs in soils and plants were negligible,while risks for adults were lower than those for children.This study provides important information on REEs in soils and plants of the northeastern Qinghai-Tibet Plateau.

Human Health Risk through Groundwater Ingestion and Dermal Adsorption： Field Investigation and Practise Using U. S.EPA Evaluation Method

Aiming to ascertain the groundwater pollution status in a southern city of China,shallow groundwater samples were collected,and 9 heavy metals Zn,Mn,Cr,Cd,Pb,Ni,Ba,Be and Hg were tested to determine the contents and environmental controlling factors,and U. S. EPA assessment method was used to evaluate the human health risk through different exposure pathways. The results indicated that the contents of heavy metals in the groundwater of the study area were relatively low,Zn,Mn,Be,Cd and Pb were frequently detected in local groundwater and the rates of exceeding the groundwater quality standard of Mn and Be were larger than 5%,and most of the heavy metals showed negative correlation with groundwater p H. The average values of non-carcinogenic and carcinogenic risk of heavy metals were lower than the threshold values,and ingestion was the major pathway that the residents were exposed to the risk. Mn,Pb and Cd were the most important heavy metals in local groundwater that should be well concerned.

Spatial Investigation of Nilüfer Stream Arsenic Pollution in Previous and Post COVID-19 Pandemic and Evaluation of Health Risks for Adult People

This study was carried out in Nilüfer Stream in Bursa City,where intensive industrial,agricultural and mining activities are existed.The temporal and spatial variation of arsenic was evaluated by examining its concentrations between March 2015 and December 2021.Values between March 2015 and December 2019 were evaluated as pre-pandemic,and values between March 2020 and December 2021 were evaluated as post-pandemic.The results were compared with national and international standards and the chronic and cancer risks were calculated for adults.When the 7-year general averages were examined,it was seen that the highest concentration was 0.0256 mg/L at the 8th Station,and the lowest concentration was 0.0182 mg/L at the 1st Station.The reason why the highest value is at the 8th station was that the wastewater of Nilüfer and Bursa Organized Industrial Zones was discharged to Bursa West Wastewater Treatment Plant before this station.After the pandemic the raises in concentrations were observed at all stations,except for the 3rd Station.This shows that the pollution load had increased in general during the pandemic.However,it was estimated that there was a decrease in the pollution load of the industrial wastewater coming to the 3rd Station,which was located after the Eastern Wastewater Treatment Plant of the City.It was observed that all stations examined were higher than drinking water standards and lower than irrigation water standards according to WHO and Turkish National Standards.All measuring stations were greater than 1 of the hazard quotient(HQ)values.In terms of human consumption risk,all stations had a chronic and carcinogenic risk according to the values before and after the pandemic.After the pandemic conditions,the HQ order of the stations was 8>10>7>9>2>6>4>1>3.In general,post-pandemic HQ values had generally increased and the risk of cancer had increased.

Evaluation of groundwater quality using pollution index of groundwater(PIG) and non-carcinogenic health risk assessment in part of the Gangetic Basin

The aim of this study was to evaluate groundwater fitness for domestic and irrigational use in Unnao district of Uttar Pradesh,India.For this study,block wise(n=16)groundwater samples were collected,and measured parameters were analyzed using the pollution index of groundwater(PIG),various irrigational indices,and graphical techniques.The results of this study suggested that most of the parameters were within the prescribed limits of WHO and BIS,excluding F-(0.4 to 2.6 mg L^(-1))and Fe^(2+)(0.1 to 1.7 mg L^(-1)).Concentrations of total dissolved solids(TDS)were exceeded the desirable limit(>500 mg L^(-1))in 43.75%of samples at some sites.The Gibbs plot revealed that groundwater chemistry was governed by rock-water interaction in the region,especially silicate weathering.The Piper plot suggested that Ca^(2+)-HCO3-is dominant hydrochemical facies in the area followed by mixed Ca^(2+)-Na^(+)-HCO_(3)^(-)type,Na^(+)-Cl^(-)type,and Na^(+)-HCO_(3)^(-)type.PIG evaluation revealed that the contribution of F-and Fe2+in groundwater degradation is high in comparison to other elements in the region,about 18.75%samples showed low pollution,while about 6.25%samples shows moderate pollution,and 6.25%samples reflected high pollution.The human health risk(HHR)assessment finding suggested that children(mean:1.36)are more vulnerable than adults(mean:1.01).Sodium absorption ration(SAR),Residual sodium carbonate(RSC),and Permeability index(PI)indicated that most of the groundwater was suitable for irrigation,whereas,Magnesium hazard ration(MHR)and Potential salinity(PS)indices suggested that only 37.5%and 56.25%of the samples were suitable for irrigational use,respectively.This regional study would help in decision making for stakeholders and relevant authorities in the execution of groundwater management and remediation plans in the area.

Legacies and health risks of heavy metals,polybrominated diphenyl ethers,and polychlorinated dibenzo-dioxins/furans at e-waste recycling sites in South China

Informal electronic-waste(e-waste)recycling sites pose substantial health risks to surrounding environments and populations,yet they are not properly regulated.In this study,the soil levels of copper,lead,cadmium,eight polybrominated diphenyl ethers(PBDEs),and 18 polychlorinated dibenzo-dioxins/furans(PCDD/Fs)were measured at two e-waste recycling sites in South China between 2014 and 2019.Both sites have been abandoned for natural restoration.Our results indicate that the mean Cd and PCDD/F levels at Site A in 2019 were higher than those recommended by current safety guidelines.Meanwhile,the highest exposure among children was 1.36×10^(−2)mg/(kg·d)for Cu,followed by 5.05×10^(−3)mg/(kg·d)for Pb,9.71 ng/(kg·d)for PBDEs,and 6.82 ng TEQ/(kg·d)for PCDD/Fs.Children were at elevated risk for health problem posed by Pb and Cu exposure at both sites(hazard quotient>1)and by PCDD/Fs at Site A.Further risk assessment was conducted on the target organs and endpoints of heavy metals and PCDD/Fs.The hazard index(HI)for the target organ mixed-risk of heavy metals was high(HI=1.27),as was that of PCDD/Fs(HI=1.66),which can disrupt endocrine function and pose a risk of reproductive toxicity in children.Owing to incomplete cleaning,contaminants persist in soils over long periods and may harm nearby environments and communities.Our study demonstrates that heavy metal,PBDE,and PCDD/F contamination have not yet been remediated,and intervention is needed to reduce pollution and associated risks in areas affected by e-waste.

Cultivars and oil extraction techniques affect Cd/Pb contents and health risks in oil of rapeseed grown on Cd/Pb-contaminated farmland

Substitute planting with rapeseed offers promise for safely using large areas of Cd/Pb-contaminated farmland.Cd/Pb distributions during rapeseed oil production were investigated and health risks posed by the oil were assessed.Tests were performed using three cultivars(Brassica rapa SYH and ZS100 and Brassica napus QY-1)and four oil extraction techniques(mechanical and low-temperature pressing and n-hexane and subcritical low-temperature butane extraction).The amounts of Cd and Pb in oil were 0.73%-8.44%and 3.14%-11.76%,respectively,of the amounts in rapeseed and were strongly affected by the cultivar and oil extraction technique.The heavy metal(HM)concentrations were lower in solvent-extracted oil(particularly subcritical low-temperature butane extracted oil,in which HMs were not detected)than mechanically pressed oil.The Cd and Pb transfer indices were lower(meaning larger proportions of HMs were retained by the rapeseed meal)for B.rapa than B.napus.This was attributed to a high HM binding protein content of B.rapa seed.Health risks to humans were assessed using a probabilistic risk assessment model.The carcinogenic risk was mainly(97.1%-99.9%)caused by Cd and poses more concern than non-carcinogenic risk.Stronger health risks are posed by mechanically pressed than solvent-extracted oil,and higher carcinogenic risks are posed to people living in rural areas than urban areas.Substitute planting with B.rapa and extracting oil with organic solvent(preferably subcritical low-temperature butane)are optimal for safely utilizing Cd/Pb-contaminated soil.Attention should be paid to the health risks posed by Cd in oil to rural populations.

Heavy metals in rice and garden vegetables and their potential health risks to inhabitants in the vicinity of an industrial zone in Jiangsu, China

Contamination of soil and agricultural products by heavy metals resulting from rapid industrial development has caused major concern. In this study, we investigated heavy metal （Cu, Zn, Pb, Cr, Hg and Cd） concentrations in rice and garden vegetables, as well as in cultivated soils, in a rural-industrial developed region in southern Jiangsu, China, and estimated the potential health risks of metals to the inhabitants via consumption of locally produced rice and garden vegetables. A questionnaire-based survey on dietary consumption rates of foodstuffs showed that rice and vegetables accounted for 64% of total foodstuffs consumed, and over 60% of rice and vegetables were grown in the local region. Average concentrations of Cr, Cu, Zn, Cd, Hg and Pb were 0.75, 2.64, 12.00, 0.014, 0.006 and 0.054 mg/kg dw （dry weight） in rice and were 0.67, 1.18, 4.34, 0.011, 0.002 and 0.058 mg/kg fw （fresh weight） in garden vegetables, respectively. These values were all below the maximum allowable concentration in food in China except for Cr in vegetables. Leafy vegetables had higher metal concentrations than solanaceae vegetables. Average daily intake of Cr, Cu, Zn, Cd, Hg and Pb through the consumption of rice and garden vegetables were 5.66, 16.90, 74.21, 0.10, 0.04 and 0.43 μg/（kg·day）, respectively. Although Hazard Quotient values of individual metals were all lower than 1, when all six metal intakes via self-planted rice and garden vegetables were combined, the Hazard Index value was close to 1. Potential health risks from exposure to heavy metals in self-planted rice and garden vegetables need more attention.

Nitrated and parent PAHs in the surface water of Lake Taihu,China:Occurrence,distribution,source,and human health risk assessment

Nitrated polycyclic aromatic hydrocarbons(NPAHs)have toxic potentials that are higher than those of their corresponding parent polycyclic aromatic hydrocarbons(PAHs)and thus have received increasing attention in recent years.In this study,the occurrence,distribution,source,and human health risk assessment of 15 NPAHs and 16 PAHs were investigated in the surface water from 20 sampling sites of Lake Taihu during the dry,normal,and flood seasons of 2018.The PAH concentrations ranged from 255 to 7298 ng/L and the NPAH concentrations ranged from not-detected(ND)to 212 ng/L.Among the target analytes,2-nitrofluorene(2-n Flu)was the predominant NPAH,with a detection frequency ranging from 85%to 90%and a maximum concentration of 56.2 ng/L.The three-ringed and four-ringed NPAHs and PAHs comprised the majority of the detected compounds.In terms of seasonal variation,the highest levels of the NPAHs and PAHs were in the dry season and flood season,respectively.Diagnostic ratio analysis indicated that the prime source of NPAHs was direct combustion,whereas in the case of PAHs the contribution was predominantly from a mixed pattern including pollution from unburned petroleum and petroleum combustion.The human health risk of NPAHs and PAHs was evaluated using a lifetime carcinogenic risk assessment model.The carcinogenic risk level of the targets ranged from 2.09×10^(-7)to 5.75×10^(-5)and some surface water samples posed a potential health risk.

Pollution level and human health risk assessment of some pesticides and polychlorinated biphenyls in Nantong of Southeast China

Food consumption is one of the key exposure routes of humans to contaminants. This article evaluated the residue levels of 51 pesticides and 16 polychlorinated biphenyls （PCBs） in selected fish and food items which were commonly consumed in the Nantong area of Jiangsu Province, Southeast China. The 51 pesticides and 16 PCBs were analyzed by highly sensitive gas chromatography- tandem mass spectrometry （GC-MS/MS）. The results showed that organochlorine pesticides such as dichlorodiphenyltrichloroethanes （DDTs）, hexachlorocyclohexanes （I-ICHs）, hexachlorobenzene （HCB） and mirex and other pesticides including chlorpyrifos, pyrethroid pesticides, metolachlor, pyridaben and trifluralin were frequently detected in the samples, which was consistent with the accumulation level and characteristics of these toxic chemicals in human adipose tissue of people living in Nantong. Meanwhile, correlation of the residue level of toxic chemicals with their physical chemical properties and historic use pattern in Nantong area was observed. Combined with dietary survey results at the same sampling locations, human health risk assessment of ingestion through the dietary route was performed. The results suggested that the non-cancer risks of the chemicals investigated can be considered negligible in the Nantong area, however, the cancer risks from lifetime dietary exposure to DDTs and HCB have exceeded the acceptable levels.

Mixed uncertainty analysis of polycyclic aromatic hydrocarbon inhalation and risk assessment in ambient air of Beijing

This article presents the application of an integrated method that estimates the dispersion of polycyclic aromatic hydrocarbons （PAHs） in air, and assesses the human health risk associated with PAHs inhalation. An uncertainty analysis method consisting of three components were applied in this study, where the three components include a bootstrapping method for analyzing the whole process associated uncertainty, an inhalation rate （IR） representation for evaluating the total PAH inhalation risk for human health, and a normally distributed absorption fraction （AF） ranging from 0% to 100% to represent the absorption capability of PAHs in human body. Using this method, an integrated process was employed to assess the health risk of the residents in Beijing, China, from inhaling PAHs in the air. The results indicate that the ambient air PAHs in Beijing is an important contributor to human health impairment, although over 68% of residents seem to be safe from daily PAH carcinogenic inhalation. In general, the accumulated daily inhalation amount is relatively higher for male and children at 10 years old of age than for female and children at 6 years old. In 1997, about 1.73% cancer sufferers in Beijing were more or less related to ambient air PAHs inhalation. At 95% confidence interval, approximately 272-309 individual cancer incidences can be attributed to PAHs pollution in the air. The probability of greater than 500 cancer occurrence is 15.3%. While the inhalation of ambient air PAHs was shown to be an important factor responsible for higher cancer occurrence in Beijing, while the contribution might not be the most significant one.

Persistence and growth of faecal culturable bacterial indicators in water column and sediments of Vidy Bay,Lake Geneva,Switzerland

The aims of this study was to investigate the persistence and the growth of culturable bacterial indicators （CBI） including total coliforms （TC） and faecal coliforms represented by Escherichia coli, enterococcus （ENT）, and aerobic mesophilic bacteria （AMB） in the surface sediments and the water column of Vidy Bay fLake Geneva, City of Lausanne, Switzerland）. The study was carded out for 60 d using microcosms containing Sewage Treatment Plant （STP） effluent and nonsterile water without CBI, as well as contaminated and non-contaminated sediments. The effects of water temperature and of organic matter associated with sediments on the survival of CBI in the sediments and the water column were observed. The number of CBI colonies in the contaminated sediments of Vidy Bay and in the STP effluent was almost identical in the order of 10^5-10^7, 10^4-10^6, 10^5-10^5, and 10^4-10^7 CFU/100 g sediment or/100 mL water for TC, E. coli, ENT, and AMB respectively. A degradation of CBI was observed in the sediments where organic mater content was low and in the water column at a temperature of 10℃ after 5 d of experimentation. In addition, a growth of CBI was observed in the sediment which is rich in organic matter at 20℃. The results of this study indicate： （1） the higher concentrations of the CBI observed in different points in the water column of Vidy Bay may not be explained only by the recent contribution of the three potential sources of the Bay contamination including STP and the Chamberonne and Flon Rivers, but also by the persistence, removal from sediment and multiplication of CBI in the sediment and water column; （2） the sediment of Vidy Bay constitute a reservoir of CBI and can even support their growth; and （3） the CBI not only survive in sediments, but also can be remobilized and increased in the water column, therefore, it become a permanent microbiological pollution in Vidy Bay.

Human health risk assessment of groundwater nitrate at a two geomorphic units transition zone in northern China

To assess groundwater nitrate contamination and its human health risks,489 unconfined groundwater samples were collected and analyzed from Zhangjiakou,northern China.The spatial distribution of principle hydrogeochemical results showed that the average concentrations of ions in descend order was HCO3-,SO42-,Na+,Ca2+,Cl-,NO3-,Mg2+and K+,among which the NO3-concentrations were between 0.25 and 536.73 mg/L with an average of 29.72 mg/L.In total,167 out of 489 samples(34%)exceeded the recommended concentration of 20 mg/L in Quality Standard for Groundwater of China.The high NO3-concentration groundwater mainly located in the northern part and near the boundary of the two geomorphic units.As revealed by statistical analysis,the groundwater chemistry was more significantly affected by anthropogenic sources than by the geogenic sources.Moreover,human health risks of groundwater nitrate through oral and dermal exposure pathways were assessed by model,the results showed that about 60%,50%,32%and 26%of the area exceeded the acceptable level(total health index>1)for infants,children,adult males and females,respectively.The health risks for different groups of people varied significantly,ranked:infants>children>adult males>adult females,suggesting that younger people are more susceptible to nitrate contamination,while females are more resistant to nitrate contamination than males.To ensure the drinking water safety in Zhangjiakou and its downstream areas,proper management and treatment of groundwater will be necessary to avoid the health risks associated with nitrate contamination.