Spatial analysis and health risk assessment of heavy metals concentration in drinking water resources

Geospatial analysis of toxic metal contamination in groundwater and associated health risks in the lower Himalayan industrial region

Once known for its clean and natural environment, the lower Himalayan region is now no exception to human-induced disturbances. Rapid industrial growth in Baddi-Barotiwala (BB) industrial region has led to degradation of groundwater resources in the area. Groundwater samples were collected from 37 locations to study the groundwater chemistry, geospatial variation of 15 toxic metals in groundwater, source apportionment, metals of concern and associated health risks in the region. The results showed rock dominated hydrogeology with decreasing order of anion and cation abundance as HCO3- > Cl- > SO42- > NO3- > Br- > F- and Ca+ > Na+ > Mg2+ > K+ > Li+ respectively. Concentrations of Iron (BDL-3.6 mg/l), Nickel (BDL-0.023 mg/l), Barium (0.22-0.89 mg/l), Lead (0.0001-0.085 mg/l) and Zinc (0.006-21.4 mg/l) were found above the permissible limits at few locations. Principal component analysis (PCA) and coefficient of variance (CV) showed both geogenic and anthropogenic origin of metals in groundwater of the BB industrial region. A consistent concentration of Uranium was detected at all the sampling locations with an average value of 0.0039 mg/l and poor spatial variation indicating its natural presence. Overall, non-carcinogenic (N-CR) risk in the study area via oral pathway was high for adults and children (Hazard Index > 1) with geogenic Uranium as the major contributor (Hazard Quotient > 1) followed by Zinc, Lead and Cobalt. Carcinogenic (CR) risk in the region was high for adults having mean value above the threshold (1E-04) with Nickel and Chromium as the metals of major concern. Spatial variation of health risks was overlayed on village boundaries of the region to identify the potential industrial sources of the metals of major concern. The results highlight the need for immediate remediation of groundwater resources in order to achieve a harmonious coexistence between industrialization and human well-being.

Assessing health risks in bottled water: chemical compounds and their impact on human health

Bottled mineral and spring water constitute one of the main sources of drinking water. Relevant legal acts in each country individually regulate the highest permitted concentrations of harmful substances in these waters. However, current regulations do not take into account newly emerging contaminants such as BPA. Analysis of the chemical composition of 72 bottled waters from the Polish market showed that undesirable elements occur in quantities that do not exceed the maximum permissible concentrations. Special attention should be paid to bottled therapeutic water, which may contain elevated concentrations of some micronutrients, such as Al, B, Ba, Fe, Mn, or Sr contributing to the pattern of health risk with excessive consumption of this type of water. The presence of BPA was confirmed in 25 tested waters. The calculated hazard index values showed that the most exposed group are children up to 12 years of age. The greatest attention should be paid to waters with high mineralisation, for which the calculated risk values are the highest.

Environmental arsenic (As) and its potential relationship with endemic disease in southwestern China

Many cases of an unknown disease exhibiting the clinical features of limb gangrene, blisters, ulceration, and exfoliation have been reported in Daping village (DV) in southwestern China. However, the pathogenesis is unknown and has puzzled doctors for many years. A preliminary study on heavy metals and symptoms indicated that arsenic might pose the greatest threat to the health of local residents. Here, to explore the sources of and factors influencing arsenic enrichment in DV, whose residents exhibit signs of arsenic poisoning, the As contents in soil, water, and plants were systematically measured. The results indicated high As contents in plant and soil samples obtained from the area, and the source of As may be linked to the weathering of black shale rock. Ingestion of soil and consumption of plants were the two main As exposure pathways among children and adults, respectively, and children exhibited a higher health risk than adults. We presume and emphasize that when extreme drought events occur, humans might face unusual risks resulting from exposure to toxic elements and the direct consumption of highly polluted water. Our study provides a new perspective and sheds light on the environmental geochemistry and health links of this disease.

Characterization of the composition, structure, and functional potential of bamboo rhizosphere archaeal communities along a chromium gradient

Introduction

Bamboo can be used in the phytoremediation of heavy metal pollution. However, the characteristics of the bamboo rhizosphere archaeal community in Cr-contaminated soil under field conditions remain unclear.

Methods

In this study, high-throughput sequencing was used to examine the rhizosphere soil archaeal communities of Lei bamboo (Phyllostachys precox) plantations along a Cr pollution gradient.

Results

The results revealed U-shaped relationships between Cr [total Cr (TCr) or HCl-extractable Cr (ACr)] and two alpha indices (Chao1 and Shannon) of archaea. We also established that high Cr concentrations were associated with a significant increase in the abundance of Thaumarchaeota and significant reductions in the abundances of Crenarchaeota and Euryarchaeota. The archaeal co-occurrence networks reduced in complexity with Cr pollution, decreasing the community's resistance to environmental disturbance. Candidatus nitrosotalea and Nitrososphaeraceae_unclassified (two genera of Thaumarchaeota) were identified as keystone taxa. The community structure of soil archaeal communities was also found to be affected by TCr, ACr, pH, total organic C, and available nutrient (N, P, and K) concentrations, with pH being identified as the most reliable predictor of the archaeal community in assessed soils.

Discussion

These findings enhance our understanding of microbial responses to Cr pollution and provide a basis for developing more refined approaches for the use of bamboo in the remediation of Cr-contaminated soils.

Assessment of potentially toxic and mineral elements in paddy soils and their uptake by rice (Oryza sativa L.) with associated health hazards in district Malakand, Pakistan

Rice, a primary food source in many countries of the world accumulate potentially harmful elements which pose a significant health hazard to consumers. The current study aimed to evaluate potentially toxic and mineral elements in both paddy soils and rice grains associated with allied health risks in Malakand, Pakistan. Rice plants with intact root soil were randomly collected from paddy fields and analyzed for mineral and potentially toxic elements (PTEs) through inductively coupled plasma optical emission spectrometry (ICP‒OES). Through deterministic and probabilistic risk assessment models, the daily intake of PTEs with allied health risks from consumption of rice were estimated for children and adults. The results of soil pH (< 8.5) and electrical conductivity (EC > 400 μs/cm), indicated slightly saline nature. The mean phosphorus concentration of 291.50 (mg/kg) in soil samples exceeded FAO/WHO permissible limits. The normalized variation matrix of soil pH with respect to Ni (0.05), Ca (0.05), EC (0.08), and Mg (0.09), indicated significant influence of pH on PTEs mobility. In rice grains, the mean concentrations (mg/kg) of Mg (463.81), Al (70.40), As (1.23), Cr (12.53), Cu (36.07), Fe (144.32), Mn (13.89), and Ni (1.60) exceeded FAO/WHO safety limits. The transfer factor >1 for K, Cu, P and Zn indicated bioavailability and transfer of these elements from soil to rice grains. Monte Carlo simulations of hazard index >1 for Cr, Zn, As, and Cu with certainties of 89.93% and 90.17%, indicated significant noncarcinogenic risks for children and adults from rice consumption. The total carcinogenic risk (TCR) for adults and children exceeded the USEPA acceptable limits of 1×10-6 to 1×10-4, respectively. The sensitivity analysis showed that the ingestion rate was a key risk factor. Arsenic (As) primarily influenced total cancer risk (TCR) in children, while chromium (Cr) significantly impacted adults. Deterministic cancer risk values slightly exceeded probabilistic values due to inherent uncertainties in deterministic analysis. Rice consumption poses health risks, mainly from exposure to Cr, Ni and As in the investigated area.

Carcinogenic and non-carcinogenic human health risk assessments of heavy metals contamination in drinking water supplies in Iran: a systematic review

The contamination of water due to heavy metals (HMs) is a big concern for humankind; particularly in developing countries. This research is a systematic review, conducted by searching google scholar, Web of Science, Science Direct, PubMed, Springer, and Scopus databases for related published papers from 2010 to July 2021, resulting in including 40 articles. Among the analyzed HMs in the presented review, the average content of Cr, Pb, Ba, Al, As, Zn, and Cd exceeded the permissible limits suggested by the World Health Organization (WHO) and 1,053 Iranian standards. Also, the rank order of Hazard Quotient (HQ) of HMs was defined as Cd>As>Cr>Pb>Li for children which means Cd has the highest non-carcinogenic risk and Li has the least. This verifies to the current order As>Cr>Pb>Fe=Zn=Cu>Cd for adults. The corresponded values of HQ and Hazard Index (HI) in most cities and villages were investigated and the results indicated a lower than 1 value, which means consumers are not at non-carcinogenic risk (HQ). Carcinogenic risk (CR) of As in the adult and children consumers in most of the samples (58.82% of samples for both groups) were investigated too, and it was more than>1.00E-04 value, which determines that consumers are at significant CR.

Concentration, spatial distribution, and non-carcinogenic risk assessment of arsenic, cadmium, chromium, and lead in drinking water in rural areas of eight cities of West Azarbaijan province, Iran

Exposure to heavy metals through drinking water can cause significant adverse health effects. The aim of the present study was to investigate the concentration, spatial distribution, and assessment of non-carcinogenic risk attributed to exposure to arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in rural areas of eight cities of the West Azerbaijan province of Iran. Eighty-five water samples were taken from randomly selected drinking water wells in the rural areas, and the concentration of the heavy metals was measured by using standard methods. The concentration distribution maps were drawn, and the non-carcinogenic health risks for ingestion and dermal exposure pathways were calculated in four age groups (including infants, children, teenagers, and adults). According to the obtained results, arsenic is considered as the most worrying pollutant among the investigated heavy metals. The maximum measured concentration for arsenic was 371.9 μg/L, which is 37 times the maximum permissible limit. The results of the health risk assessment illustrate that exposure to heavy metals via dermal contact do not pose significant non-carcinogenic risks. However, the calculated non-carcinogenic risks for oral exposure to arsenic were very high and concerning. The highest hazard quotient for oral exposure to arsenic was related to rural of city G (82.64). It is recommended to take the necessary measures as soon as possible regarding the supply of safe drinking water in the studied areas.

Assessment of Essential and Potentially Toxic Elements in Water and Sediment and the Tissues of Sciaena deliciosa (Tschudi, 1846) from the Coast of Callao Bay, Peru

The lorna drum Sciaena deliciosa is a coastal demersal species and one of the underlying artisanal fisheries in some areas of Peru, and is also a source of protein for Peruvian coastal dwellers. The investigation addresses concern about the environmental impact on this fish species and the potential risks to human health through the consumption of contaminated seafood. This research endeavors to assess the concentration of potentially toxic and essential elements in the muscle and liver tissues of S. deliciosa, in addition to the presence thereof in water and sediment capture areas on the coast of Callao, Peru. The study revealed that, in water samples, Ag, Ni, and Zn exceed Peruvian standards, but were below international standards, and Ba, P, Se, and Sn exceed international standards. In the sediments, As, Cd, Pb, Fe, and Zn were above international standards. In the fish, S. delicious muscle demonstrated As, Hg, and Pb exceeding at least one international standard. In the liver, As, Hg, Pb, and Cu exceed international standards. The study approach increased accuracy in risk assessments, offering crucial insights into the interplay between heavy metal pollution, water quality, and animal health, informing risk management strategies. Future studies can explore the long-term effects of heavy metal exposure on different organisms and consider their cumulative impact on health.

Distribution characteristics, source identification and health risk assessment of trace metals in the coastal groundwater of Taizhou City, China

This study was carried out to evaluate and analyze the fluctuations in groundwater for certain trace metals (Fe, Mn, Cu, Zn, Al, Cd, Cr, Pb, As, and Se) in Taizhou City over three years (2020-2022), evaluate the potential human health risks due to the consumption of groundwater. To quantify the spatiotemporal changes in groundwater trace metals, the heavy metal pollution index (HPI) and heavy metal evaluation index (HEI) were utilized. Furthermore, multivariate statistical methods were utilized to distinguish the sources of trace elements. Deterministic health risk assessment and Monte Carlo health risk simulation methods were employed to evaluate human health risks associated with exposure to trace metals. The results indicate that areas with higher pollution are in the south-central region, with low HPI increasing from 50% to 75% and low HEI from 68.75% to 81.25%, reflecting improved water quality. Correlation matrix analysis and principal component analysis (PCA) pinpointed anthropogenic sources as major trace metal contributors. Cr and As concentrations were associated with farming activities, Cd and Pb concentrations showed links to local industries such as e-waste recycling and shipbuilding. Furthermore, Cu levels in groundwater was influenced by the combined effects of industry, agriculture, and urban sewage discharge. Based on the hazard quotient (HQ) and hazard index (HI) calculations, the majority of groundwater samples did not exceed the reference values, indicating acceptable noncarcinogenic risks for both adults and children. However, the analysis of carcinogenic risk (CR) and uncertainty revealed an overall decreasing trend in carcinogenic risk, with Cr and Cd possessing the highest potential for causing carcinogenic risks. The sensitivities were 46.3%, 53.3%, and 70.3% for Cr, and 18.8%, 27.6%, and 9.3% for Cd.

Spatial trend and probabilistic health risk assessment of heavy metals, nitrate, and fluoride in groundwater resources, West Azerbaijan province, Iran

The quality of water resources used for drinking and their health effects is vitally important. The present study investigated the concentrations of F-, NO3-, and metal elements like Hg, Mn, As, and Pb in the groundwater resources and their health risk assessment on the west margin of Urmia Lake, Iran. Sampling points were selected and taken from 121 groundwater resources in the summer of 2014. Heavy metals (Pb, As, Mn, and Hg) were measured by ICP-OES (inductively coupled plasma optical emission spectrometer, model: Arcos, Germany), and some ions (Na+, NO3-, F-, and Cl-) by flame photometer and spectrophotometer according to the standard methods, respectively. The nitrate concentration range in groundwater samples measured from 1.7 to 137 mg/L and fluoride from 0.4 to 4.5 mg/L. The probabilistic method and Monte Carlo simulation were used to estimate carcinogenic and noncarcinogenic risks. The concentration of study elements in most samples was obtained in the WHO (World Health Organization) recommended range. The order of HM (heavy metal) concentration is based on the overall mean: Mn > As > Hg > Pb. The HI (hazard index ) level was found to be more than 1 for noncarcinogenic risk for As and NO3- and permissible risks for the other elements and fluoride. ELCR (excess lifetime cancer risk) levels of As were acceptable, except for some sampling points, the central region in the study area, near the seashore of Urmia Lake. Finally, it can be stated that the groundwater resources in the studied area are acceptable for drinking in most places. Still, due to the effects of As and NO3- contaminated water, the quality is unacceptable for drinking in some places. So, monitoring water quality is recommended by finding contamination sources to decrease the health risks of drinking consumption.

Acrylamide toxicity in aquatic animals and its mitigation approaches: an updated overview

Acrylamide (ACR) is widely applied in various industrial activities, as well as in the water purification process. Furthermore, ACR is synthesized naturally in some starchy grains exposed to high temperatures for an extended time during the cooking process. Because of its widespread industrial usage, ACR might be released into water stream sources. Also, ACR poses a high risk of contaminated surface and ground-water resources due to its high solubility and mobility in water. Furthermore, animal studies have indicated that ACR exposure may cause cancer (in many organs such as lung, prostate, uterus, and pancreas), genetic damage (in both somatic and germ cells), and severe effects on reproduction and development. Recently, numerous studies have shown that ACR has a mild acute cytotoxic impact on aquatic species, particularly during early life stages. Besides, wide-spectrum usage of ACR in many industrial activities presented higher environmental risks as well as major hazards to consumer health. This literature was designed to include all potential and accessible reports on ACR toxicity related with aquatic species. The Preferred Reporting Items for Systematic Reviews were applied to evaluate the risk effects of ACR on aquatic organisms, the ACR sub-lethal concentration in the ecosystem, and the possible protective benefits of various feed additives against ACR toxicity in fish. The major findings are summarized in Tables 2 and 3. The primary aim of this literature was to specify the hazards of ACR toxicity related with fish welfare and possible suggested strategies to reduce its risks.

Technical guidelines for risk assessment of heavy metals in traditional Chinese medicines

BACKGROUND

Heavy metals are considered a global concern because they can deteriorate human health. This guideline aims to scientifically evaluate health risk of heavy metals in TCM and to propose a reference for decision making in developing TCM-related health policies.

METHODS

Using a multidisciplinary approach, a steering committee oversaw the development of the guideline. To obtain a reasonable and accurate risk assessment, key exposure assessment parameters for TCM, e.g., exposure frequency (EF), exposure duration (ED), and daily ingestion rate (IR) were obtained from surveys. In addition, transfer rates for heavy metals from Chinese medicinal materials (CMM) to decoctions or preparations were examined.

RESULTS

Based on the scientific theory of risk control, the guideline was designed systematically, and principles and procedures for the risk assessment of heavy metals in TCM were identified. The guideline can be utilized to assess the risk of heavy metals in CMM and Chinese patent medicines (CPM).

CONCLUSION

This guideline may help standardize the risk assessment of heavy metals in TCM, advance regulatory standards for heavy metals in TCM, and ultimately improve human health through scientific TCM usage in clinic.

The concentration of potentially toxic elements (PTEs) in drinking water from Shiraz, Iran: a health risk assessment of samples

The existence of potentially toxic elements (PTEs) in water bodies has posed a menace to human health. Thus, water resources should be protected from PTEs, and their effect on the exposed population should be investigated. In the present investigation, the concentrations of PTEs such as lead (Pb), mercury (Hg), manganese (Mn), and iron(Fe) in the drinking water of Shiraz, Iran, were determined for the first time. In addition, hazard quotient, hazard index, cancer risk, and sensitivity analysis were applied to estimate the noncarcinogenic and carcinogenic impacts of Pb, Hg, Mn, and Fe on exposed children and adults through ingestion. The mean concentrations (µg/L) of Pb, Hg, Mn, and Fe were 0.36, 0.32, 2.28, and 8.72, respectively, in winter and 0.50, 0.20, 0.55, and 10.36, respectively, in summer. The results displayed that Fe concentration was more than the other PTEs. PTE concentrations were lower than the standard values of the Environment Protection Agency and World Health Organization. Values of the degree of contamination and heavy metal pollution index for lead, mercury, manganese, and iron were significantly low (< 1) and excellent (< 50), respectively. Based on the Spearman rank correlation analysis, positive and negative relationships were observed in the present study. The observations of the health risk assessment demonstrated that mercury, lead, iron, and manganese had an acceptable level of noncarcinogenic harmful health risk in exposed children and adults (hazard quotients < 1 and hazard index < 1). The carcinogenic risk of lead was low (< E - 06), which can be neglected. Monte Carlo simulation showed that water intake rate and mercury concentration were the most critical parameters in the hazard index for children and adults. Lead concentration was also the most crucial factor in the cancer risk analysis. The results of the present study proved that the drinking water of Shiraz is safe and healthy and can be confidently consumed by people.

Urinary arsenic and health risk of the residents association in contaminated-groundwater area of the urbanized coastal aquifer, Thailand

Determining of arsenic (As) exposure was conducted in 110 residents which divided into two groups using the WHO guidelines for As in drinking water of 10 μg/L. Moreover, questionnaires with face-to-face interviews were used to make a health risk assessment and to determine the associated factors. The median of As in urine was 61.33 μg/L (5.38-600.86 μg/L), accounting for 68.18% of participants who exposed to the contaminated groundwater had obviously high urinary As levels, exceeded the normal value of 50 μg/L of As, as set by the National Health and Nutrition Examination Survey (NHANES). The major factor affecting As in urine was the As contaminated groundwater. Pearson's chi-squared test showed that the urinary As level was influenced on the different groups of As level in groundwater (p-value <0.001). Multiple linear regression confirmed that the actual risk factors of As in urine were the As level in groundwater and the oral exposure route but not the dermal contact. Meanwhile binary logistic regression revealed that all socio-demographic factors were not influenced. Approximately 45.45% of the area had the HI above the risk level of 1, mostly via groundwater drinking pathway. The estimated total cancer risk values, 5.11 × 10^-6 to 2.08 × 10^-3, were higher than the safe level of 10^-6. For long-term exposure, the As concentration and exposure duration were the most variables influencing health risk level. This finding suggests that chronic As exposure should be monitored and also the groundwater should be improved to provide the safe drinking water for the residents.

Quality assessment and prediction of municipal drinking water using water quality index and artificial neural network: A case study of Wuhan, central China, from 2013 to 2019

The sanitary security of drinking water is closely related to human health, but its quality assessment mainly focused on limited types of indicators and relatively restricted time span. The current study was aimed to evaluate the long-term spatial-temporal distribution of municipal drinking water quality and explore the origin of water contamination based on multiple water indicators of 137 finished water samples and 863 tap water samples from Wuhan city, China. Water quality indexes (WQIs) were calculated to integrate the measured indicators. WQIs of the finished water samples ranged from 0.24 to 0.92, with the qualification rate and excellent rate of 100 % and 96.4 %, respectively, while those of the tap water samples ranged from 0.09 to 3.20, with the qualification rate of 99.9 %, and excellent rate of 95.5 %. Artificial neural network model was constructed based on the time series of WQIs from 2013 to 2019 to predict the water quality thereafter. The predicted WQIs of finished and tap water in 2020 and 2021 qualified on the whole, with the excellent rate of 87.5 % and 92.9 %, respectively. Except for three samples exceeding the limits of free chlorine residual, chloroform and fluoride, respectively, the majority of indicators reached the threshold values for drinking. Our study suggested that municipal drinking water quality in Wuhan was generally stable and in line with the national hygiene standards. Moreover, principal component analysis illustrated that the main potential sources of drinking water contamination were inorganic salts and organic matters, followed by pollution from distribution systems, the use of aluminum-containing coagulants and turbidity involved in water treatment, which need more attention.

Trace elements in public drinking water in Chinese cities: Insights from their health risks and mineral nutrition assessments

The trace elements in the public drinking water have a duality: on the one hand, trace elements play an important role in maintaining human metabolism; on the other hand, high trace elements levels lead to significant health risks. To determine the impacts of trace elements in the public drinking water on physical health in China, water samples were collected from 314 Chinese cities to analyze the concentrations and spatial distributions of trace elements on a national scale. On this basis, the non-carcinogenic health risk assessments and the nutrient-based scores of trace elements (NSTEs) were applied to evaluate the public drinking water quality in terms of safety and nutrition. Most of the water samples were weakly alkaline: pH values fell in the range of 6.62-8.54, with a mean of 7.80. The results indicated that Sr and F^- had the highest concentrations in public drinking water, with averages of 0.3604 mg/L and 0.2351 mg/L, respectively. Moreover, hazard index (HI) values in different regions followed the order: northwest China (NWC) > northern China (NC) > Qinghai-Tibetan Plateau (QT) > southern China (SC). The percentages of water samples with HI > 1 in SC, NC, NWC, and QT were 5.49%, 16.82%, 25.81%, and 16.67%, respectively, indicating that the public drinking water in some cities had significant non-carcinogenic health risks. In addition, the intakes of Mn, Fe, Cu, and Rb through public drinking water made negligible contributions to their recommended nutrient intakes. In contrast, trace elements like Sr, F, B, Li, Mo, etc., contributed a lot. The NSTEs in NWC and most parts of NC were relatively high with averages of 8.0300 and 11.2082, respectively; however, the NSTEs in SC and the northeast part of NC were low with averages of 3.3284 and 5.2106, respectively. The results from this study provide a reference for establishing the public drinking water standards and improving drinking water quality.

Physicochemical analysis of wastewater generated from a coating industry in Mauritius

The coating industry is one of the most important consumers of water and chemicals and consequently is a major water polluter in Mauritius. The focus of this study was to characterise wastewater generated by a coating industry in Mauritius. The objectives were to develop a wastewater sampling strategy and to analyse the pollutant parameters as per Mauritian regulations. The wastewater samples were analysed for physicochemical properties and metal abundances over a period of 6 months. The physicochemical parameters analysed were pH, electrical conductivity (EC), true colour, total suspended solids (TSS), biological oxygen demand (BOD₅), chemical oxygen demand (COD), nitrate, phosphate, sulphate and free chlorine. The wastewater samples were also analysed for metal ions such as sodium, potassium, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel and zinc. The results of the physicochemical parameters indicated the presence of biologically resistant organic matters in all the wastewater samples with elevated values of BOD₅ and COD, and low biodegradability index, respectively. The coating industry wastewater samples were acidic and saline in nature. Moreover, they presented high concentrations of TSS, free chlorine and sodium ions compared to standard limits promulgated by the Mauritian Government. Spearman's rank correlation matrix with non-linear regression analysis showed significant associations among the measured parameters which were found to have a common origin in the coating industry wastewater. This research will be useful for regular monitoring and setting up an adequate coating industry wastewater treatment for the potential reuse in production processes in Mauritius.

Bioavailability and health risk assessment of potentially toxic elements in salty water environment of Okposi, Southeastern Nigeria

Abstract

This study is to determine some physicochemical parameters and potentially toxic elements (PTE) in water samples collected from a borehole, a stream and a lake in Okposi, Nigeria, for their quality status and the human health risk of exposure to the waters. The physico-chemical properties: pH, electrical conductivity (EC), salinity, nitrate and sulphate, were determined by standard methods, while the level of PTE contamination was analysed by Flame Atomic Absorption Spectroscopy (FAAS). The results show that the levels of physicochemical parameters in the water samples are within the World Health Organisation (WHO) permissible limit. The PTE concentrations (mg/L) in the samples are in the ranges of 0.12–0.35 (Cr); 0.06–0.19 (Cu); 0.24–2.45 (Fe); 0.0–0.06 (Mn); 0.00–0.75 (Pb); and 0.0–02 (Zn). The levels of Cr and Pb in all the samples, except Pb in the downstream water, are above the WHO permissible limits, indicating that the waters are contaminated and unsafe for drinking. PTE form complexes with anions in water at high EC and salinity which reduces availability of toxic metals to organisms. Therefore, toxicity of PTE in the samples is in decreasing order: Upstream > Downstream > Lake water > borehole water. Calculations of hazard quotients shows possible adverse effects on adults and children on dermal contact with the waters due to Cr. Children might get cancer due to Pb on ingestion of water from the studied borehole, the Lake and the Upstream waters. Statistical analysis suggests that the geology of the area influenced PTE contamination of the water bodies.

Article highlights

Spatial analysis and human health risk assessment of elements in ground water of District Hyderabad, Pakistan using ArcGIS and multivariate statistical analysis

Availability of clean drinking water is a basic necessity of human population. Therefore, the current study was taken up for spatial analysis and human health risk assessment of elements in Ground water of District Hyderabad, Pakistan. Evaluation of 10 potential hazardous elements in one hundred eighteen samples of ground water from district Hyderabad, Pakistan was done to assess their natural and anthropogenic origin and possible effects on living organisms and human health. Based on statistical tools of Pearson Co-relation, Metal Clustering and Principal Component Analysis (PCA), three groups of elements were produced; First group included Mn, Fe, B and Cr, the second group contained Cu, Ni and As while third group included Pb, Cd and Zn. Higher Relative Standard Deviation (RSD) values of Cu, Ni, As, Pb, Cd and Zn showed their anthropogenic origin while Mn, Fe, B and Cr were found with lower concentration that indicated their natural origin. Histograms and box-plots of Mn, Fe, B and Cr were found to be normally distributed while these parameters were appeared abnormal for Cu, Ni, As, Pb, Cd and Zn. Risk assessment was quantified by hazard quotient (HQ) and cancer risk for both adult and child. Non-carcinogenic risks as depicted by HQs of all the 10 metal(loid)s were below the recommended HQ threshold of 1 for both child and adult. However, highest HQ was calculated for B (child 0.300 and adult 0.338) followed by the values for Mn and Ni. The potential risks of combined effect of all the 10 metal(loid)s through ingestion of groundwater was assessed using HI and calculated to be 0.694 for adult and 0.566 for child. This indicates the potential health risk of these metal(loid)s to human due to the consumption of the groundwater of district Hyderabad for drinking purpose. Considering the geometric mean for the studied area, carcinogenic risk of As through oral intake was calculated i.e. 1.50 × 10^-4 and 2.62 × 10^-5 for the adult and child However, this carcinogenic risk is 1.91 × 10^-5 and 3.28 × 10^-6 for Cd in adult and child and 1.94 × 10^-3 and 3.32 × 10^-4 for Cr in adult and child, respectively. Since the cancer risk 6exceeded the target risk of 1 × 10^-4 for Cr i.e. 1.94 × 10^-3 in adult, it can thus be considered as 'non-acceptable'. Spatial maps of elements produced by ArcGIS showed the hotspots of potential hazardous elements such as highest concentration of elements like Zn, Pb and Cd was found in urban areas while highest concentration of Cu, Ni and As was observed near Phulleli canal which passes from Hyderabad City and may contain contamination from waste material of residential area due to their anthropogenic activities.

In Situ Measurements of Domestic Water Quality and Health Risks by Elevated Concentration of Heavy Metals and Metalloids Using Monte Carlo and MLGI Methods

The domestic water (DW) quality of an island province in the Philippines that experienced two major mining disasters in the 1990s was assessed and evaluated in 2021 utilizing the heavy metals pollution index (MPI), Nemerow’s pollution index (NPI), and the total carcinogenic risk (TCR) index. The island province sources its DW supply from groundwater (GW), surface water (SW), tap water (TP), and water refilling stations (WRS). This DW supply is used for drinking and cooking by the population. In situ analyses were carried out using an Olympus Vanta X-ray fluorescence spectrometer (XRF) and Accusensing Metals Analysis System (MAS) G1 and the target heavy metals and metalloids (HMM) were arsenic (As), barium (Ba), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni), and zinc (Zn). The carcinogenic risk was evaluated using the Monte Carlo (MC) method while a machine learning geostatistical interpolation (MLGI) technique was employed to create spatial maps of the metal concentrations and health risk indices. The MPI values calculated at all sampling locations for all water samples indicated a high pollution. Additionally, the NPI values computed at all sampling locations for all DW samples were categorized as “highly polluted”. The results showed that the health quotient indices (HQI) for As and Pb were significantly greater than 1 in all water sources, indicating a probable significant health risk (HR) to the population of the island province. Additionally, As exhibited the highest carcinogenic risk (CR), which was observed in TW samples. This accounted for 89.7% of the total CR observed in TW. Furthermore, all sampling locations exceeded the recommended maximum threshold level of 1.0 × 10⁻⁴ by the USEPA. Spatial distribution maps of the contaminant concentrations and health risks provide valuable information to households and guide local government units as well as regional and national agencies in developing strategic interventions to improve DW quality in the island province.

Arsenic, iron, and manganese in groundwater and its associated human health risk assessment in the rural area of Jashore, Bangladesh

This study investigated groundwater pollution and potential human health risks from arsenic, iron, and manganese in the rural area of Jashore, Bangladesh. Study results show that the mean value of groundwater pH is 7.25 ± 0.31, with a mean conductivity of 633.94 ± 327.41 μs/cm, while about 73, 97, and 91% of groundwater samples exceeded the Bangladesh drinking water standard limits for As, Fe, and Mn, respectively. Groundwater pollution evaluation indices, including the heavy metal pollution index, the heavy metal evaluation index, the degree of contamination, and the Nemerow pollution index, show that approximately 97, 82, 100, and 100% of samples are in the high degree of pollution category, respectively. Spatial distribution exhibited that the study area is highly exposed to As (73%), Fe (82%), and Mn (46%). In the case of non-carcinogenic health risk via oral exposure, about 94% of samples suggest a high category of risk for infants, and 97% of samples are found to be at high risk for children and adults. The carcinogenic risk of arsenic via an oral exposure pathway suggests that approximately 97% of the samples are found to be at high risk for infants, and all of the samples are at high risk for both adults and children.

Non-carcinogenic risk assessment of exposure to heavy metals in underground water resources in Saraven, Iran: Spatial distribution, monte-carlo simulation, sensitive analysis

Groundwater aquifers are considered the second most abundant water supply for drinking water all over the world. In Iran, ground waters are commonly employed for drinking water, irrigation, and industrial purposes. Heavy metals (HMs) pose human concerns about the groundwater contamination; these pollutants are recognized to be capable of bio-accumulation, long persistence in the natural environment, and toxic effects. In the present research, the content of HMs: Chromium (Cr), Cadmium (Cd), and Lead (Pb) were detected in 89 water samples collected in 2018 by underground water supplies (active wells) of Saravan city. Hazard Quotient (HQ) and Monte Carlo Simulation approach with 10,000 repetitions were applied to discover the human non-carcinogenic impacts of HMs in four groups of ages (adults, teenagers, children, and infants) of consumers. The concentrations of Cr, Pb, and Cd were in the range of 0.49-20, 0.1 to 58.34, and 0.11-12.8 μg/L, respectively. The mean HQ calculated due to exposure to Pb (0.0018-0.0023), Cr (0.0112-0.0186), and Cd (0.0370-0.0615) were lower than one. The findings of sensitivity analysis revealed that HMs concentration had the most contribution effect on human non-carcinogenic risk analysis in four different exposed populations. This study could assist researchers to perform more comprehensive studies with more samples. Therefore, further research is required for decision-makers to plan proper measurements properly.

Potentially Toxic Element Levels in Atmospheric Particulates and Health Risk Estimation around Industrial Areas of Maros, Indonesia

Air quality deterioration is a major environmental problem in Indonesia. This study evaluated the levels and health risks of potentially toxic elements (PTEs) in Maros Regency, Indonesia. Total suspended particulate matter was collected from industrial areas for PTE (Al, Pb, Cr, Cu, Ni, As and Zn) analysis using inductively coupled plasma optical emission spectrometry (ICP-OES). Samples were collected from six critical areas in the Bantimurung region as that is where marble, cement and limestone industries are located. A calculation of the non-carcinogenic and cancer risks was performed to determine the potential health exposures in adults and children. A Monte Carlo simulation with 10,000 iterations and a sensitivity analysis was carried out to identify the risk probability and the most sensitive variable contributing to cancer risk from PTE exposure in humans. The results showed that the concentration of PTEs decreased in the order of Zn > Al > Cr > Pb > Cu > Ni > As in the wet season, and Zn > Al > Pb > As > Cr > Cu > Ni in the dry season. The hazard index (HI) value for children was 2.12, indicating a high non-carcinogenic risk for children. The total cancer risk (TCR) values in adults and children were 3.11 × 10⁻⁵ and 1.32 × 10⁻⁴, respectively, implying that both are at risk for developing cancer. The variables with the most contribution to cancer risk from As, Cr and Pb exposure in adults and children were As concentration (33.9% and 41.0%); exposure duration (ED) (34.3%) and SA (40.7%); and SA (98.7 % and 45.4%), respectively. These findings could be used as the scientific basis for public health intervention and to raise awareness of the harmful health effects of particulate bound PTEs

Arsenic-contaminated groundwater and its potential health risk: A case study in Long An and Tien Giang provinces of the Mekong Delta, Vietnam

The occurrence of arsenic (As) in groundwater (drilled well water) that were used for drinking, cooking, and personal hygiene and its risks to human health in Long An and Tien Giang provinces (Mekong delta, Vietnam) were evaluated in this study. The average As concentrations were 15.92 ± 11.4 μg/L (n = 24, Long An) and 4.95 ± 4.7 μg/L (n = 24, Tien Giang). The average concentrations of As in Long An had not reached the WHO and QCVN 01: 2009/BYT healthy drinking water standard (10 μg/L). When used as a source of water for drinking and daily activities, arsenic-contaminated groundwater may have a direct impact on human health. The risk assessment from groundwater established by the US Environmental Protection Agency (USEPA) was conducted. The risk assessment showed that the average cancer risk (CR) values were 8.68 × 10^-4 (adults) and 2.39 × 10^-3 (children) for Long An, and 2.70 × 10^-4 (adults) and 7.43 × 10^-4 (children) for Tien Giang. These results were significantly higher than the CR (1 × 10^-4) proposed by the USEPA. The adverse health effect was therefore specifically warned by the use of arsenic-contaminated groundwater. This research offers valuable knowledge for efficient water management approaches to guarantee local communities' health protection.

Human Health Risk Assessment of Trace Elements in Tap Water and the Factors Influencing Its Value

(1) Background: The influence of tap water fittings construction and internal pipe-work on the release of heavy metals was investigated. (2) Methods: A statistical approach was applied for the examination of the chemistry of tap water in five different cities in southern Poland. In total, 500 samples were collected (from 100 to 101 samples in each city). The sampling protocol included information on the construction of the water supply network and the physicochemical parameters of measured tap water. (3) Results: The statistical analysis allowed to extract the crucial factors that affect the concentrations of trace elements in tap water. Age of connection, age of tap, age of pipe-work as well as material of connection, material of pipe-work and material of appliance reveal the most significant variability of concentrations observed for As, Al, Cd, Cu, Fe, Mn, Pb, and Zn. Calculated cancer risks (CRs) decrease with the following order of analysed elements Ni > Cd > Cr > As = Pb and can be associated with the factors that affect the appearance of such elements in tap water. The hazard index (HI) was evaluated as negligible in 59.1% of the sampling points and low in 40.1% for adults. For children, a high risk was observed in 0.2%, medium in 9.0%, negligible in 0.4%, and low for the rest of the analysed samples.

Heavy metal concentrations in rivers and drinking water of Esmeraldas (Ecuador) under an intermittent water supply service

Universal access to safe water is a major global goal, but these efforts could be at stake because drinking water sources are becoming polluted in many developing countries. Chlorine, major ions, and heavy metals were measured in rivers and drinking water of Esmeraldas because potential pollution sources raise concerns about the quality of the water supply, and because users have developed strategies to cope with water shortages including collecting river water and water distributed by tankers, storing water at home, and consuming commercial bottled water. We sampled water from the water distribution system (WDS) and the Esmeraldas and Teaone rivers including the intake to the potabilization plant, water distributed by tankers, and commercial bottled water. Most of the samples collected from the Esmeraldas and Teaone rivers, the WDS, and tankers complied with drinking water standards, but higher concentration of cadmium and other metals in the eastern part of the city is an indication of corrosion inside the WDS. Commercial bottled and WDS water showed similar heavy metal concentrations, but regular consumption of some brands may lead to higher exposure to arsenic and mineral deficiencies. Chlorine concentrations in the water supplied by the WDS were below the values required for safe disinfection, and in-house chlorination is uncommon in the city. Strengthening pollution control in the Esmeraldas river, monitoring corrosion of the WDS, and promoting point-use chlorination and better water handling practices are required to secure a safer water supply in the long term.

Survey of six metal contaminants and impurities and eleven metals and alloy components released from stainless-steel sheets on the Chinese market

The release of metal elements from stainless-steel products in contact with food may endanger human health. To protect human health, different countries or international organisations have formulated corresponding regulations or technical guidelines. Limits for only five metal elements are stipulated in the China National Food Safety Standard (GB 4806.9) and food simulants and test conditions are fixed regardless of the actual use condition. In this study, inductively coupled plasma mass spectroscopy and inductively coupled plasma optical emission spectroscopy were used to measure the concentrations of six metal contaminants and impurities and 11 metals and alloy component released from stainless-steel sheets on Chinese market. The effects were also investigated on metal release of six grades (201, 202, 304, 430, 443, and 30Cr13) and 6 exposure conditions (food simulant 5 g L^-1 citric acid or 4 vol% acetic acid, contact temperature 70 °C or 100 °C, and contact time 2 h, 0.5 h, or 0.5 h followed by ambient temperature for 24 h). For reusable stainless-steel sheets, especially for grade 30Cr13, it was essential to perform three consecutive release tests to check compliance. However, there was no need to conduct three consecutive release tests for the other five grades if the results of the first test met the regulations. It was recommended that 5 g L^-1 citric acid should be used as food simulant and contact temperature and time should be based on the actual using conditions. No relationships were found between metal release amounts and contact test temperature or time. The specific release limits for Pb, Cr, As, Cd, and Ni should be lowered and Al, Mn, and Fe be added in GB 4806.9. The results of this study can be a reference for further analysis of the release behaviour of metal elements in actual stainless-steel products.

Presence of heavy metals in drinking water resources of Iran: a systematic review and meta-analysis

Water quality is one of the most important indices for public health especially for drinking water consumptions. This study was conducted to survey the presence of heavy metals in drinking water resources of Iran using a systematic review and meta-analysis. The literature search was conducted in data bases of PubMed, Web of Science, EMBASE, Scopus, Google Scholar, and some Persian databases up to 31 July 2018. Of all the articles reviewed (1151 articles), 61 papers were eligible for systematic review. Results indicated variable heterogeneity between studies for different pollutants (I² between 0 and 100). A subgroup analysis was performed for three different types of water resources such as drinking water, groundwater, and surface water to find the possible source of the heterogeneity. The pooled mean concentration level of iron was the highest at 255.8 (95% CI = 79.48-432.13 μg/l) and vanadium the lowest at 3.21 (95% CI = 1.45-4.98 μg/l). The sequence of metal concentration (μg/l) in descending order is as follows: Fe (255.8) > B (159.81) > Al (158.5) > Zn (130.73) > As (85.85) > Mn (51.61) > Cu (47.98) > Se (42.68) > Pb (37.22) > Co (22.76) > Mo (18.92) > Ni (16.79) > Cr (13.47) > Hg (4.49) > Cd (4.19) > V (3.21). The mean pooled concentration level of Al, As, Se, Pb, and Cd was higher than the WHO guideline and Iran Standard, and the rest of the metals had lower mean pooled concentration level. Pb and Cd were the common heavy metals that existed in all subgroups. As a recommendation, the relationship assessment of water parameters and heavy metals could be addressed in future studies of Iran's water resources.

Deterministic and probabilistic human health risk assessment approach of exposure to heavy metals in drinking water sources: A case study of a semi-arid region in the west of Iran

In the current study, the concentration of heavy metals (Ba, Mn, Pb, and Cd) in drinking water resources of 328 villages in Hamadan Province were measured using ICP-OES apparatus during two dry (September 2018) and wet (April 2019) seasons. The assessment of the non-carcinogenic risk of selected heavy metals was conducted based on the recommendations of the USEPA. Also, sensitivity analysis and uncertainty of the effective variables were performed using Monte-Carlo simulations. Based on the results, Mn level in drinking water samples ranged 0.08-25.63 μg/L and 0.08-20.03 μg/L in dry and wet seasons, respectively. Similarly, Ba levels in water samples ranged 0.15-70.13 μg/L and 0.84-65 μg/L. Also, Cd and Pb concentrations in all sampling sites were below the limits of detection (LOD) of the ICP-OES apparatus. The hazard index (HI) values for adult and children were 2.17 × 10^-3 and 3.29 × 10^-3, respectively, which show a lack of non-carcinogenic risk for the examined heavy metals (Mn and Ba) to the local inhabitants. The results of the sensitivity analyses for adults and children revealed that two variables including metal concentration and ingestion rate of drinking water (IR) had the highest positive effects on the non-carcinogenic risk estimates. It was also found that there was no significant non-carcinogenic risk for the local residents in the studied area due to drinking water consumption.

Determination and health risk assessment of trace elements in the tap water of two Sub-Cities of Addis Ababa, Ethiopia

Water is an essential component of all living things on earth and the contamination of water by heavy metals can cause detrimental health effects. This study aimed to determine the health risk posed by trace elements (Fe, Zn, Cu, Mn, Ni, Cr, Cd, Co, Pb, and As) present in the drinking water supplies of Gullele and Akaki-Kality Sub-Cities, upstream and downstream parts of Addis Ababa, respectively. The concentrations of the potentially toxic trace elements in the water samples were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). The highest concentration of the heavy metals was observed for Iron. Cadmium and cobalt were not detected in any of the tap water samples. Samples from Gullele contained higher levels of Fe and Mn, 220.3 ± 0.17 and 19.78 ± 0.08 μg/L, respectively compared to Akaki-Kality, 38.87 ± 0.14 and 2.08 ± 0.01 μg/L, respectively. Conversely, tap water from Akaki-Kality contained significantly higher levels of As than that from Gullele. Additionally, Cr and Ni were detected only in samples from Akaki-Kality, which might be due to the various industries in the area. The highest incremental lifetime cancer risk was found for arsenic, with values for children and adults in Akaki-Kality 2.50 × 10-4 and 4.50 × 10-4, respectively. Likewise, in Gullele Sub-City, it was 5.00 × 10-5 and 1.00 × 10-4 for adults and children, respectively. The results indicate that carcinogenic risk occurrence is probable from As in both studied areas.

Health and ecological risk assessment and simulation of heavy metal-contaminated soil of Tehran landfill

The toxic effects of heavy metals in landfill soils have become a significant concern for human health. The present study aimed to estimate the health and ecological risk associated with soil heavy metal in Tehran landfill. A total of 48 soil samples were taken from the landfill and residential area and were analyzed using inductively coupled plasma-optical emission spectroscopy. The results showed the following order for heavy metal levels in landfill soil: Al > Fe > Mn > Zn > Cr > Cu > Pb > Ni > Co > As > Cd. The investigated ecological indices showed moderate to high heavy metal pollution. The principal component analysis revealed that the concentration of Pb, Cu, Zn, Cr, and Ni in the investigated soil was mainly affected by anthropogenic activities. Although the hazard index (HI) value in children was 6.5 times greater than that of adults, this value for both landfill workers and residents of the target area was at a safe level (HI ≤ 1). In the residential area, the Incremental Lifetime Cancer Risk (ILCR) value of adults (1.4 × 10-4) was greater than children ILCR value (1.2 × 10-4). Monte Carlo simulation and sensitivity analysis showed input variables such as exposure duration, exposure frequency, Ni concentration, soil ingestion rate, and As concentration have a positive effect on ILCR of 41.3, 24.3, 9.4, 9.0, and 2.9% in children, respectively. These results indicate that the landfill soil and the adjacent residential area are affected by heavy metal contamination and that the current solid waste management policies need to be revised.

Geographical origin differentiation of Chinese Angelica by specific metal element fingerprinting and risk assessment

Traceability offers significant information about the quality and safety of Chinese Angelica, a medicine and food homologous substance. In this study, a systematic four-step strategy, including sample collection, specific metal element fingerprinting, multivariate statistical analysis, and benefit-risk assessment, was developed for the first time to identify Chinese Angelica based on geographical origins. Fifteen metals in fifty-six Chinese Angelica samples originated from three provinces were analyzed. The multivariate statistical analysis model established, involving hierarchical cluster analysis (HCA), principal component analysis (PCA), and self-organizing map clustering analysis was able to identify the origins of samples. Furthermore, benefit-risk assessment models were created by combinational calculation of chemical daily intake (CDI), hazard index (HI), and cancer risk (CR) levels to evaluate the potential risks of Chinese Angelica using as traditional Chinese medicine (TCM) and food, respectively. Our systematic strategy was well convinced to accurately and effectively differentiate Chinese Angelica based on geographical origins.

Status of chromium accumulation in agricultural soils across China (1989-2016)

The first national-scale assessment of chromium (Cr) contamination in China's agricultural soils was performed based on 1625 sites analysed with 1799 previously published papers. Spatial and temporal variations were assessed, and the ecological risk was estimated. The range of Cr concentrations in farmland soil is 1.48-820.24 mg/kg. At approximately 4.31% and 0.12% of the sampling sites, Cr concentrations exceeded the screening value (150 mg/kg) and the control value (800 mg/kg), respectively (GB15618-2018). Cr concentrations decreased in the following order: Southwest > Northwest > East > South > Northeast > Central > North China. Moreover, the Cr accumulation rate in agricultural soils may have decreased during 2011-2016, possibly due to government-led changes in China's industrial structure and policies limiting the discharge of polluted industrial wastes. Linear correlations were observed between the application amounts of fertilizers and Cr concentrations in the soil, indicating that the application of nitrogen, phosphorus and potassium fertilizers is an important contributor of Cr in agricultural soils. Additionally, geoaccumulation index (I_geo) values for Cr showed that more than 83.4% of the sampling sites were uncontaminated, with high I_geo values distributed in some areas, especially those with mining and electroplating industries. Overall, this study details the Cr contamination status of agricultural soils in China and provides insights for policymakers enacting measures to prevent pollution.

Human health risk assessment for exposure to BTEXN in an urban aquifer using deterministic and probabilistic methods: A case study of Chennai city, India

The aquifer in Tondiarpet, Chennai, had been severely contaminated with petroleum fuels due to an underground pipeline leakage. Groundwater samples were analyzed quarterly for priority pollutants such as benzene, toluene, ethylbenzene, xylenes, and naphthalene (BTEXN) using purge and trap gas chromatography and mass spectrometer from 2016 to 2018. The maximum concentrations of BTEXN in groundwater at the site were found to be greater than the permissible limits significantly. Among the five sampling locations (MW1, MW2, MW3, MW4, and MW5), mean BTEXN levels were found to be higher near MW2, confirming the source location of petroleum leakage. Human health risk assessment was carried out using deterministic and probabilistic methods for exposure to BTEXN by oral and dermal exposure pathways. Risk analysis indicated that mean cancer and non-cancer risks were many times higher than the allowable limits of 1E-06 and 1 respectively in all age groups (children, teens, and adults), implying the adverse health effects. Oral exposure is predominately contributing (60-80%) to the total health risk in comparison to the dermal exposure route. Variability and uncertainty were addressed using the Monte Carlo simulations and the resultant minimum, maximum, 5th, 95th^, and mean percentile risks were predicted. Under the random exposure conditions to BTEXN, it was estimated that the risk would become unacceptable for >98.7% of the exposed population. Based on the sensitivity analysis, exposure duration, and ingestion rate are the crucial variables contributing significantly to the health risk. As part of the risk management, preliminary remediation goals for the study site were estimated, which require >99% removal of the BTEXN contamination for risk-free exposures. It is suggested that the residents of Tondiarpet shouldn't utilize the contaminated groundwater mainly for oral ingestion to lower the cancer incidence related to exposure to BTEXN.

Amperometric determination of heavy metal using an HRP inhibition biosensor based on ITO nanoparticles-ruthenium (III) hexamine trichloride composite: Central composite design optimization

A novel horseradish peroxidase (HRP) enzyme inhibition biosensor based on indium tin oxide (ITO) nanoparticles, hexaammineruthenium (III) chloride (RUT), and chitosan (CH) modified glassy carbon electrode (GCE) was developed. The biosensor fabrication process was investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The amounts of ITO nanoparticles and RUT were optimized using a 2² central composite design for the optimization of electrode composition. The detection limits were determined as 8 nM, 3 nM, and 1 nM for Pb²⁺, Ni²⁺, and Cd²⁺, respectively. The inhibition calibration curves of the biosensor were found to be within the range of 0.009-0.301 µM with a sensitivity of 11.97 µA µM^-1 cm^-2 (0.85 µA µM^-1) for Pb²⁺, 0.011-0.368 µM with a sensitivity of 10.84 µA µM^-1 cm^-2 (0.77 µA µM^-1) for Ni²⁺, and 0.008-0.372 µM with a sensitivity of 10.99 µA µM^-1 cm^-2 (0.78 µA µM^-1) for Cd²⁺. The type of HRP inhibition by Pb²⁺, Ni²⁺ and Cd²⁺ was investigated by the Dixon and Cornish-Bowden plots. The effects of possible interfering species on the biosensor response were examined. The analysis of Pb²⁺, Ni²⁺, and Cd²⁺ in tap water was demonstrated using the HRP/ITO-RUT-CH/GCE with satisfactory experimental results. The proposed method agreed with the atomic absorption spectrometry results.

Status of copper accumulation in agricultural soils across China (1985-2016)

The first national-scale assessment of Cu contamination of agricultural soils covering 1731 sites in China was performed based on 1837 published papers. The temporal and spatial variations from 1985 to 2016 in the Cu concentrations and the ecological and health risks associated with Cu exposure were analyzed. Approximately, 21.02% of the sampling sites revealed Cu concentrations that exceeded the screening value (50.00 mg/kg; GB15618-2018). The Cu concentrations differed among five geographical regions in the decreasing order of South China > West China > East China > Northeast China > North China. Notably, concentration of Cu in agricultural soils have begun to diminish since 2011 due to reduced heavy metal inputs. Cu mainly originated from anthropogenic activities such as mining and agricultural activities. Linear correlations were observed between the amounts of fungicides and fertilizers applied and the Cu concentrations in the soils, which suggested that the application of fungicides and fertilizers is an important contributor to the accumulation of Cu in soils. Additionally, the geoaccumulation index (I_geo) and ecological risk index (E_fⁱ) values implied that pollution and ecological risk resulting from soil Cu concentration were in low levels. The hazard index (HI) values were higher for children than for adults. Therefore, children should be prioritized for protection from heavy metal pollution. Overall, this study details the status of Cu contamination of agricultural soils in China, and thus provides insights for policymakers regarding the preventive measures.

Risk assessment of hybrid rain harvesting system and other small drinking water supply systems by game theory and fuzzy logic modeling

The complexity and uncertainties affecting drinking water supply systems and threatening hazards require a comprehensive and effective risk assessment to increase the reliability of drinking water safety, especially for small or household systems. This study presents a hierarchical structure risk assessment model based on fuzzy logic and game theory to assess the quantity, treatment technology, distribution systems, and storage at household level risks, for small systems in remote areas. Game theory combined with an analytical hierarchy process with entropy weight method is employed. The efficiency tradeoffs in risk from use of this model are examined in a case study which includes three types of small systems (i.e., rainwater harvesting, surface water combined with rainwater and groundwater) in Gansu Province, China. Fifteen risk factors are employed, with evaluation results showing that "Source water" is the most important factor. The hybrid (surface & rainwater) system in the driest year has "Medium" risk with the highest aggregate risk value as a result of source water availability and the distribution system is the most susceptible to failure. The groundwater system consistently has the lowest risk in the case study area. The utility of the model provides scientific support to decision-makers to plan for the most effective risk mitigation measures for water supply systems in remote areas. A cloud-based online-platform employing this methodology has been developed to facilitate the adoption of the methodology in remote areas with mobile or internet access.

Cadmium and chromium levels in water and edible herbs in a risk assessment study of rural residents living in Eastern Iran

In arid and semi-arid regions of Iran, water is supplied by qanats, underground channels where pollution is suspected, but unestablished. The aim of this study was thus to run a risk assessment study regarding the levels of cadmium (Cd) and chromium (Cr) in qanat water and edible herbs (Adiantum capillus-verenis, Chara globularis and Plantago lanceolata) growing in qanats in 14 villages in South Khorasan Province in Iran between April and August 2018. Samples were collected in qanats from the same sampling points, and after mineralization in nitric and perchloric acids were analyzed for metal concentrations by means of atomic absorption spectrometry. Concentrations of Cd and Cr found in water were not high (0.028 and 1.091 μg L^-1, respectively) and contamination parameters revealed no pollution. The ingestion rate of water and the exposure frequency to metals were the most relevant variables in the model of a sensitivity analysis, but the Hazard Quotient indicated no risk of non-carcinogenic health problems to consumers of the water. The Carcinogenic Risk parameter suggested, however, that there is a risk of these consumers' developing cancer. Concentrations found in herbs were higher than in water but remained below permissible thresholds. Hazard Quotient values of three species studied in the case of children and A. capillus-verenis in the case of adults indicated a potential non-carcinogenic health risk linked with eating them. The study reveals that further research to include many of the qanats across Iran should be carried out to verify the scale of the risk suggested. Graphical abstract.

Simultaneous appraisals of pathway and probable health risk associated with trace metals contamination in groundwater from Barapukuria coal basin, Bangladesh

In this study, we analyzed 33 groundwater samples from the Barapukuria coal basin (BCB), Bangladesh for 10 trace metals (TMs) using Atomic Absorption Spectroscopy. Pathways and associated probable health risk were appraised by employing multivariate statistical approaches, health risk model and Monte-Carlo simulation. Except for the Cu, Cr and Zn concentrations, the mean concentrations of all TMs in the basin were above the permissible water quality limits set by Bangladesh and international standards. Correlation coefficient and principal component analysis, supported by cluster analysis indicated that anthropogenic inputs were more contributed to the elevated concentrations of TMs compared to geogenic sources as the major reasons of groundwater pollution in the basin. The results of non-carcinogenic risk appraisal depicted that hazard index (HI) values for both adults and children were exceeded the safe limits (>1.0) except for few locations, indicating serious health risks on the human via oral and dermal absorption pathways. However, the carcinogenic risk values of Cd and Cr exceeded the US EPA range of 1 × 10^-6 to 1 × 10^-4, with higher risk for children than adults, with oral intake as the key exposure pathway. A sensitivity study identified the concentration of Cr, exposure frequency and ingestion rate for carcinogenic effect as the most sensitive parameters influencing the probable health risk. Overall, the results suggest that Cr in drinking water could cause detrimental effects to exposed local residents; thus, strict health regulation and groundwater management should concentrate on Cr contamination in groundwater from the coal basin.

Exposure risk assessment of nine metal elements in Chongqing hotpot seasoning

Atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS) were used to analyze the contents of nine metal elements (Pb, As, Hg, Cd, Cr, Fe, Mn, Cu, Zn) in 100 groups of Chongqing hotpot seasoning (CHS). Meanwhile, Crystal Ball software based on Monte Carlo simulation technology was used to assess the exposure risk of the nine metal elements in CHS for people of different ages in Chongqing. In general, the average Hazard Index (HI) of the nine metal elements is 0.306 < 1, indicating no non-carcinogenic risks from these nine elements for inhabitants of Chongqing under the current consumption level of CHS. Children (ages 7–13) and adult women have higher chronic daily intake (CDI) than adult males. The carcinogenic risk of Pb, As and Cd are within the acceptable risk level (10⁻⁶ to 10⁻⁴). The sensitivity analysis suggests that the contents of the nine metal elements and daily intake (PIR) in CHS were positively correlated with the risk index, while the body weight was negatively correlated with the risk index. This study provides a scientific basis for guiding the safe consumption of Chongqing hotpot, and provides a theoretical basis for the development of safety-compliant CHS quality standards.

Atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS) were used to analyze the contents of nine metal elements (Pb, As, Hg, Cd, Cr, Fe, Mn, Cu, Zn) in 100 groups of Chongqing hotpot seasoning (CHS).

Spatial distribution of fluoride in drinking water and health risk assessment of children in typical fluorosis areas in north China

China has been suffering from endemic fluorosis for the past 30 years. This study investigated fluoride concentrations in 10 districts of Tianjin, China, to illustrate their spatial distribution characteristics and potential human health risks. The results showed fluoride concentration of 0.01-6.30 mg L^-1 with a mean value of 0.99 mg L^-1, and 78.82% of water fluoride reaches the standard for drinking water (1.5 mg L^-1). Higher fluoride levels were recorded in deep well pumps supply zones, and more potential changes in fluoride occurred was positively correlated with pH in groundwater. Mean value of fluoride in drinking water in 10 districts followed the order of WQ > BC > JZ > NH > BD > BH > JN > JH > DL > XQ. Estimations of non-carcinogenic risk for drinking water indicated that mean hazard quotient values of fluoride for combined pathways (i.e., oral ingestion and dermal absorption) were >1.0 for all age groups of WQ and BC. The results also showed that the estimated risk primarily came from the ingestion pathway. Risk levels for children varied obviously, generally in the order of 1-4y > 4-7y > 7-9y (years old). In the central tendency center and reasonable maximum exposure conditions, estimated risks were 1.25, 1.12, 0.771 and 3.66, 3.29, 2.27, respectively. The results supply material information for health authorities in fluorosis areas to put forward more efficient policies to control the endemic diseases. Attention should be paid to the formulation of health promotion strategies and measures to reduce fluoride intake in order to protect the health of residents.

Assessment of the possibility of using deciduous tree bark as a biomonitor of heavy metal pollution of atmospheric aerosol

The aim of the research was to assess the possibility to use deciduous tree bark in the biomonitoring of urban areas. The tree bark taken from various deciduous tree species growing in the Opole Province (south-western Poland) was used for the research. The bark was collected from tree trunks in the period of June 2-26, 2017. Concentrations of the heavy metals were determined in the barks by flame atomic absorption spectrometry (FAAS). On the basis of the research, it was determined that type of tree, distance from pollution source, elevation off the ground and the side of trunk from which bark was sampled all influence the research results. A comparison of the values of coefficient of variation CV demonstrated that the bark Quercus robur and Betula pendula is more heterogeneous, e.g. for Fe CV_{Quercus robur} is 48.0 % and CV_{Betula pendula} = 42.3 %, compared to Fagus sylvatica (CV_Fe = 22.6%). In order to limit the influence of environmental factors (e.g. air movement caused by vehicles and pedestrians) on the samples pollution level with analytes, it seems that the optimum level for collecting the samples is 1.5-2.0 m. It was demonstrated that deciduous tree bark can be used as bioindicator in assessing the pollution of atmospheric aerosol by heavy metals, due to its occurrence in urban areas. However, it is important to validate all stages of the analysis procedure that uses deciduous tree bark.

Probabilistic risk assessment and spatial distribution of potentially toxic elements in groundwater sources in Southwestern Nigeria

The study investigated the concentration of potentially toxic heavy metals (PTHM) in groundwater sources (hand-dug wells and boreholes), spatial distribution, source apportionment, and health risk impact on local inhabitants in Ogun state. One hundred and eight water samples from 36 locations were analysed for Cr, Ni, Pb, Fe, Mn, Mg, Ca and Al. Mean values of 0.013, 0.003, 0.010, 0.088, 0.004 and 3.906 mg/L were obtained for Pb, Cr, Ni, Fe, Mn, and Al respectively at Iju district. Meanwhile, the average values of Pb, Ni, Fe, Mn, and Al concentrations at Atan district were 0.008, 0.0023, 0.011, 0.003, and 1.319 mg/L respectively. Results also revealed that the 44.4% and 11.13% of the borehole and well-water samples surpassed the World Health Organization limits for Pb at Atan. In Iju, the concentration of Pb and Al were relatively high, exceeding the stipulated standard in 100% of the samples. The Multivariate statistical analysis employed produced principal factors that accounted for 78.674% and 86.753% of the variance at Atan and Iju region respectively. Based on this, PTHM were traced to geogenic sources (weathering, dissolution, leaching) and anthropogenic emissions from industrial activities. In addition, the hazard quotient values obtained from the health risk assessment identified potential non-carcinogenic risk due to Pb via ingestion route. Ni was found to have high carcinogenic risk on adult and children, having exceeded the threshold limit. The outcome of the carcinogenic risk assessment revealed that 88.67% (for adults) and 1.12% (for children) of the cancer risk values surpassed the specified limits at Iju, whereas the cancer risk values were considerably lesser at Atan. In conclusion, the report of this study should serve as a beacon that will spark up strategic planning, comprehensive water resource management, and extensive treatment schemes in order to address the health complications linked with environmental pollution.

Probabilistic risk assessment of occupational exposure to volatile organic compounds in the rendering plant of a poultry slaughterhouse

In this study, occupational exposure to volatile organic compounds (VOCs) in the rendering plant of poultry slaughterhouse was determined and subsequently, carcinogen and non-carcinogenic risks were assessed using the US Environmental Protection Agency (USEPA). National Institute for Occupational Safety and Health (NIOSH) methods of 1501 and 1600 were used to measure VOCs in the breathing zone of the workers. Samples were analyzed by GC/MS. Carcinogenic and non-carcinogenic risks and sensitivity analysis were carried out using Monte Carlo simulations technique. The concentration of benzene and CS₂ was higher than the occupational exposure limits (OEL). The hazard quotient (HQ) values for all measured compounds was more than 1, which indicating the high potential for non-carcinogenic risks. Furthermore, the calculated Lifetime Cancer Risks (LCR) for carcinogenic compounds revealed that cancer risk due to benzene is higher than the maximum acceptable level provided by USEPA (10^-6). Based on the sensitivity analysis, the concentration and exposure frequency are the most important variable influencing both carcinogen and non-carcinogenic risks. Therefore, the concentration levels of the VOCs and exposure frequency should be controlled using engineering control measures.

Carcinogenic and Non-carcinogenic Risk Assessment of Heavy Metals in Groundwater Wells in Neyshabur Plain, Iran

The present work reports the As, Cr, Cu, Pb, Zn, and Fe concentrations of drinking water samples in Neyshabur Plain, Iran. This study aimed also to ascertain the potential consumers' health risk of heavy metal intake. Heavy metal concentrations were analyzed by inductively coupled plasma optical emission spectrometry. The highest and lowest average values in the analyzed water samples were observed for Fe (9.78 ± 5.61 μg/L) and As (1.30 ± 2.99 μg/L), respectively. These values were well below the limits recommended by the World Health Organization and the Iranian national standard. Heavy metal pollution index and heavy metal evaluation index were used to evaluate drinking water quality. The risk index was calculated by chronic daily intake and hazard quotient according to the United States Environmental Protection Agency approach. Heavy metal pollution index in all the samples was less than 100, indicating that it is a low-level heavy metal. The total risk of all heavy metals in the urban environment varied from 40.164 × 10^-7 to 174.8 × 10^-7. In this research, the maximum average of risk belonged to lead and copper with the respective values of 60.10 × 10^-7and 33.99 × 10^-7 from the selected wells. However, considering the toxic effect of some elements, including Pb and As, in the chronic exposure of consumers, we suggest a continuous evaluation and monitoring of drinking water resources.

Aerosols from a wastewater treatment plant using oxidation ditch process: Characteristics, source apportionment, and exposure risks

The study of aerosol dispersion characteristics in wastewater treatment plants (WWTPs) has attracted extensive attention. Oxidation ditch (OD) is a commonly implemented process during biological wastewater treatment. This study assessed the component characteristics, source apportionment, and exposure risks of aerosols generated from a WWTP using the OD process (AWO). The results indicated that the aeration part of oxidation ditch (ODA) exhibited the highest concentrations and proportions of the respiratory fractions (RF) of bacteria, Enterobacteriaceae, Staphylococcus aureus, and Pseudomonas aeruginosa. Some pathogenic or opportunistic-pathogenic bacteria and carcinogenic metal(loid)s were detected in the AWO. The source apportionment results indicated that the outdoor wastewater treatment processes and ambient air contributed to the constitution of the AWO. The indoor aerosols were mainly constituted by composition of the wastewater treatment process such as the sludge dewatering room (SDR). The pathogenic or opportunistic-pathogenic bacteria with eight genera (Colinsella, Dermatophilus, Enterobactor, Erycherichia-Shigella, Ledionella, Selenomonas, Xanthobacter, and Veillonella) were largely attributed to wastewater or sludge. The risk assessment suggested that inhalation was the main exposure pathway for aerosols (including bacteria and metal(loid)s). Additionally, As indicated the highest non-carcinogenic risks. Furthermore, As, Cd, and Co were associated with high carcinogenic risks. The ODA and sludge dewatering room (SDR) indicated the highest carcinogenic and non-carcinogenic risks of metal(loid)s, respectively. Thus, the AWO should be sufficiently researched and monitored to mitigate their harmful effects on human health, particularly with regard to the health of the site workers.

Appraising spatial variations of As, Fe, Mn and NO3 contaminations associated health risks of drinking water from Surma basin, Bangladesh

This study aims to appraise the spatial variations and pathways of groundwater contaminations and associated health risks in the Surma basin, Bangladesh using geostatistics, Fuzzy GIS technique and health risk modelbased on ninety groundwater samples. The results show that the mean concentrations of As, Fe, Mn and NO₃ are below the Bangladesh water quality standard, whereas As, Fe and Mn concentrations exceed World Health Organization guideline values in several sampling sites. The compositional study identifies weathering of source rocks, reductive dissolution of Fe and Mn-oxyhydroxide minerals and various anthropogenic inputs as the key sources of groundwater contamination. The kriged maps show the elevated risks of Fe, Mn and NO₃ concentrations from the south to northern parts and As concentration from the north to southwestern parts of the Surma basin. The results of fuzzy GIS maps confirm the outcomes of kriged maps. Cross validation results show better performance of indicator kriging over probability kriging. The results also show a spatial heterogeneity with As, Fe, Mn and NO₃ concentrations, indicating the low to medium risk categories. A health risk assessment is performed using hazard quotient (HQ) and hazard index (HI). The HQ values imply that the risk of contamination through oral ingestion pathway is medium to high levels for both adults and children as the trace elements show HQ values more than one. It is found that drinking water of several upazilas exhibits high contamination and that children are more susceptible to the non-carcinogenic and carcinogenic risks than adults in the study area.