Occurrence and health risk assessment of selected metals in drinking water from two typical remote areas in China

Heavy metals in Ethiopian drinking water and public health risks: Insights from nationwide and regional analysis

The ambitious sustainable development goal (SDG) 6 of the United Nations, which aims to achieve universal access to safe water and sanitation by 2030, remains elusive for many developing countries like Ethiopia. This is often due to a multitude of intricate factors, including the escalating degradation of water quality. Here, we present a comprehensive nationwide and regional analysis of heavy metal pollution in drinking water sources and the associated human health risks in Ethiopia based on a dataset of 11 heavy metal concentrations (n = 975) collated from available studies. Results indicate significant variations in heavy metal pollution in drinking water sources in Ethiopia, with 44 % of the total concentration exceeding maximum permissible limits. The mean concentrations were ranked as follows: Pb (1.92 mg/L) > Zn (1.25 mg/L) > Fe (0.56 mg/L) > Mn (0.43 mg/L) > Cu (0.40 mg/L) > Co (0.30 mg/L) > As (0.12 mg/L) > Ni (0.12 mg/L) > Cr (0.10 mg/L) > Cd (0.06 mg/L) > Hg (0.04 mg/L). We found that children are more vulnerable to non-carcinogenic health risks than adults, with the highest hazard quotient (HQ) exceedances of up to a factor of 1823 and 762, respectively. Furthermore, a Monte Carlo-based probabilistic risk assessment highlighted significant concerns regarding co-exposure to multiple heavy metals. The measured concentrations, ingestion rates, and exposure frequencies were identified as sensitive parameters. Overall, a higher risk was attributed to Pb and As, with river drinking water sources and the Tigray region requiring immediate mitigation measures. In conclusion, the findings emphasize the urgent need to test and purify water before consumption and to implement effective public health interventions. Furthermore, a multifaceted approach including regular monitoring, source protection, and proper waste management is recommended to expedite the achievement of SDGs and promote water sustainability in resource-limited Ethiopia and sub-Saharan Africa.

Occurrence and Health Risks of Heavy Metals in Drinking Water of Self-Supplied Wells in Northern China

Self-supplied wells, an important water resource in remote and scattered regions, are commonly deteriorated by environmental pollution and human activity. In this study, 156 self-supplied well-water samples were collected from remote and scattered areas of Inner Mongolia (NMG), Heilongjiang (HLJ), and the suburbs of Beijing (BJ) in Northern China. Twenty-four heavy metals were identified by using the inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES), and the associated human health risks were assessed by using standards of the US Environmental Protection Agency (US EPA). The concentrations of four heavy metals (As, Fe, Mn, and Tl) in HLJ, one heavy metal (Tl) in BJ, and ten heavy metals (Al, As, B, Cr, Fe, Mn, Mo, Se, Tl, and Zn) in NMG exceeded the limits set by China or the World Health Organization (WHO). The total carcinogenic risk (TCR) and total non-carcinogenic risk (THQ) exceeding set limits mainly occurred in NMG, compared to HLJ and BJ. Moreover, As accounted for 97.87% and 60.06% of the TCR in HLJ and BJ, respectively, while Cr accounted for 70.83% of the TCR in NMG. The TCR caused by Cd in all three areas had a negligible hazard (<10^-4). As accounted for 51.11%, 32.96%, and 40.88% of the THQ in HLJ, BJ, and NMG, respectively. According to the results of the principal component analysis, heavy metals in well water from HLJ and NMG mainly originated from mixed natural processes and anthropogenic sources, whereas, in BJ, most heavy metals probably originated from natural sources. In the future, long-term monitoring of heavy metals in water from self-supplied wells should be conducted for an extensive range of well-water sites, and well water with high As contamination should be monitored more and fully assessed before being used as a drinking-water source.

Groundwater Health Risk Assessment Based on Monte Carlo Model Sensitivity Analysis of Cr and As–A Case Study of Yinchuan City

Groundwater is an important resource for domestic use and irrigation in the Yinchuan region of northwest China. However, the quality of groundwater in this region is declining due to human activities, with adverse effects on human health. In order to study the effects of chemical elements in groundwater on human health, the human health risk of drinking groundwater was calculated based on the actual situation in China and on the U.S. Environmental Protection Agency (USEPA) model. Moreover, the sensitivity of contaminant exposure in drinking water wells was quantified using Monte Carlo simulation to minimize uncertainty in conjunction with USEPA risk assessment techniques, with the aim to identify the major carcinogenic factors. In addition, Visual Minteq was used to analyze the possible ionic forms of the major factors in the hydrogeological environment of the study area. The results showed that the mean CR values for As were 2.94 × 10−0.5 and 5.93 × 10−0.5for the dry and rainy seasons, respectively, while for 2018 they were 5.48 × 10−0.5 and 3.59 × 10−0.5, respectively. In parallel, the CR values for children for 2017 were 6.28 × 10−0.5 and 1.27 × 10−0.4, respectively, and 1.17 × 10−0.4 and 7.67 × 10−0.5, respectively, indicating a considerably higher carcinogenic risk for children than for adults. results of the sensitivity analysis of Cr6+ and As using Crystal Ball software showed association values of 0.9958 and 1 for As and 0.0948 and 0 for Cr in the dry and rainy seasons in 2017, and 0.7424 and 0.5759 for As and 0.6237 and 0.8128 for Cr in the dry and rainy seasons in 2018, respectively. Only in the rainy season of 2018, the association values for As were lower than those for Cr, indicating that As is more sensitive to total carcinogenic risk. The results of the visual coinage model analysis showed that among all the possible ionic forms of As, the activity of HAsO42− had the largest logarithmic value and that of H3AsO4 had the smallest value, regardless of pH changes. This indicates that HAsO42− is the ionic form of As with the main carcinogenic factor in the hydrogeological environment of the study area. Therefore, corresponding environmental control measures need to be taken in time to strengthen the monitoring and control of As, especially HAsO42−, in the groundwater of the study area. This study is of great significance for Yinchuan city to formulate groundwater pollution risk management and recovery.

A home-made sampling system coupled to hectowatt-MPT mass spectrometry in positive ion mode to confirm target ions of copper and zinc from Poyang Lake, China

A novel home-made H₂SO₄-Nafion (HN) tube sampling system coupled to a line ion trap mass spectrometer (LTQ-MS) with a versatile ambient ionization source, hectowatt microwave plasma torch (HMPT), has manifested unique advantages for picking directly metal elements in aqueous samples and acquiring the fully characteristic MPT mass spectra of copper and zinc composite ions. Here, we report the development of a novel HN-HMPT-LTQ-MS for metal elements assay based on environmental water to analyze samples of Poyang Lake, China. Detailed multi-stage tandem mass spectra show that the general structural form of target ions is [M(NO₃)_x(H₂O)_y(OH)_z]⁺ for the positive ion mode. Under the optimized conditions, the proposed method provided low limits of detection (LODs) of 0.23 μg^.L^-1 for ⁶³Cu⁺ and 1.1 μg^.L^-1 for ⁶⁶Zn⁺, with relative standard deviations (RSDs) of less than 12.7% by MPT-LTQ-MS. This new result has met the requirements of national standards (GB 5750.6-2006) and is only about one magnitude order larger than the LOD of ICP-MS method. A wide linear response range of about 4 orders of magnitude for the method with linear coefficients (R²) of 0.99709 - 0.99962 for copper and zinc tested was in accordance with that of ICP-MS. Except for the recovery of 79% for the third sample and 123.8% for the seventh sample, the present method also provided good recoveries (84 - 119.3%) in spiked 10 batches of drinking water samples. Furthermore, it is envisioned that the developed approach might build a powerful hectowatt-MPT-MS platform for food security detection, drug analysis, and origin traceability.

Characterization of drinking groundwater quality in rural areas of Inner Mongolia and assessment of human health risks

Groundwater is an important natural resource of drinking water in rural areas in Inner Mongolia, China. In this study, 4438 drinking groundwater samples were collected from the rural areas of 81 counties in Inner Mongolia, and were analyzed for 16 parameters, including pH, total hardness (TH), chemical oxygen demand (COD), total dissolved solids (TDS), sulfate (SO42-), chloride (Cl-), fluoride (F-), iron (Fe), manganese (Mn), arsenic (As), cadmium (Cd), hexavalent chromium (Cr), lead (Pb), aluminum (Al), cuprum (Cu), zinc (Zn). The groundwater quality was evaluated with water quality index (WQI) and human health risk assessment (HRA). Monte Carlo simulation were applied for the uncertainty and sensitivity analysis in the health risk assessment. The spatial map was employed based on the inverse distance weighted (IDW) interpolation technique. The results reveal that while the hazard quotient (HQ) suggests that the risk of single element contamination is feeble, the hazard index (HI) indicates a potential health risk for the local population. The observed cumulative carcinogenic risk (CCR) indicates a probable risks of carcinogenic health hazards in the study area. The sensitivity analysis revealed that daily ingestion rate (IR), exposure frequency (EF), and the concentrations of As, Mn, F-, and Cr are the most influential parameters for health hazards. The highly polluted areas are mainly distributed in the central and western regions of Inner Mongolia, including Xianghuangqi, New Barag Zuoqi, and Togtoh. It is observed that the groundwater may cause a potential health risk after long-term ingestion. The results of this study will contribute to groundwater management and protection in Inner Mongolia.

The role of education and income for cognitive functioning in old age: A cross-country comparison

OBJECTIVES

Previous studies have shown that higher education promotes cognitive health. This effect, however, is embedded in the living conditions of a particular country. Since it is not clear to what extent the country and its specific living standards are necessary preconditions for the observed effect, we investigated whether the impact of education and income on cognitive functioning differs between countries.

METHODS

Analyses were based on harmonized data from the World Health Organization's multi-country Study on global AGEing and adult health, the Health and Retirement Study, and the Survey of Health, Ageing and Retirement in Europe of over 85,000 individuals aged 50 years and older. Analyses were conducted via multivariate regression analyses and structural equation modeling adjusted for age, gender, marital status, health status, and depression.

RESULTS

The effect of education was twice as large as the effect of income on cognitive functioning and indirectly moderated the effect of income on cognitive functioning. The effect sizes varied strongly between countries. The country's gross domestic product per capita seems to influence cognitive functioning.

CONCLUSIONS

Our findings indicate that education has a dominant effect on cognitive functioning in people aged 50 years and older, which might even offset the adverse implications of living with low income on cognitive health. Therefore, expanding efforts to achieve universal education are essential to mitigate health disparities due to low income and early life disadvantages, including chances for good cognitive functioning over the life-span.

Spatial variation, water quality, and health risk assessment of trace elements in groundwater in Beijing and Shijiazhuang, North China Plain

Metal(loid)s pollution of groundwater in northern China is of great concern due to the increasing shortage of fresh water resources. In the present study, total 159 of groundwater samples were collected from the Miyun-Huairou-Shunyi (MHS) districts in Beijing city and the Hutuo River Plain (HRP) in Shijiazhuang city. Nineteen trace elements dissolved in groundwater were measured. Results showed that Al (12.3 %), Mn (5.3%), Zn (1.8%), As (1.8%), and Pb (1.8%) in the MHS samples, and Mn (2.2%) in the HRP samples exceeded their standard threshold of WHO and China. Exceedance of trace elements was attributed to both geochemical background and local human activities. Human health risk assessment showed that local consumers were exposed at a low level of health risk, except in specific area with a high level of arsenic. Elements of arsenic and chromium were important risk contributors in the two regions. The risk of oral exposure was greater than that of skin uptake. Children were more susceptible to non-carcinogenic risk and less to carcinogenic risk than adults. A Nemerow index and CRITIC-weighted WQI were applied to classify groundwater quality. The results from the two methods were comparable to a large extend. More population living in plain rather than mountain resulted in a gradual deterioration trend of groundwater quality from mountain to plain. The samples with poor water quality were almost collected in the area with heavy industrial and agricultural activities. The CRITIC-weighted WQI was recommended for groundwater quality assessment. A simple classification criterion was reformulated based on the MHS hazard index analysis. The groundwaters in the two research fields were not seriously polluted, but potential risks should not be ignored.

Potential risk assessment of groundwater to address the agricultural and domestic challenges in Ordos Basin

The safety of groundwater has been a great concern for irrigation and drinking purposes in recent decades due to the increasing impacts of anthropogenic activities. There are several standards to evaluate the groundwater quality for different utilization purposes. In this paper, 804 samples covering the entire Ordos Basin across five provinces were used to evaluate the irrigation suitability and human health risks. The results showed that the sequence of cationic concentration was Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ > NH₄ ⁺, and the anion concentration was HCO₃ ^- > SO₄ ^2- > Cl^- > NO₃ ^- > F^- > NO₂ ^-. For drinking purposes, TDS, Na⁺, SO₄ ^2-, F^-, TH and NO₃ ^- exceed seriously the regulated standard in the study area. For irrigating purposes, 80% of the water in the study area belongs to "good water" according to the evaluation of salinity and alkalinity. Saline water which is not suitable for irrigation accounts for about 9%. High health risks of fluoride ions are mainly observed to the samples representing the western part of the study area, while the health risks of nitrates spread throughout the study area. Health risk is not only related to location, but also varies with age, and it is found that children suffer more threats than adults.

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.

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

The heavy metals available in drinking water can be considered as a threat to human health. Oncogenic risk of such metals is proven in several studies. Present study aimed to investigate concentration of the heavy metals including As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn in 39 water supply wells and 5 water reservoirs within the cities Ardakan, Meibod, Abarkouh, Bafgh, and Bahabad. The spatial distribution of the concentration was carried out by the software ArcGIS. Such simulations as non-carcinogenic hazard and lifetime cancer risk were conducted for lead and nickel using Monte Carlo technique. The sensitivity analysis was carried out to find the most important and effective parameters on risk assessment. The results indicated that concentration of all metals in 39 wells (except iron in 3 cases) reached the levels mentioned in EPA, World Health Organization, and Pollution Control Department standards. Based on the spatial distribution results at all studied regions, the highest concentrations of metals were derived, respectively, for iron and zinc. Calculated HQ values for non-carcinogenic hazard indicated a reasonable risk. Average lifetime cancer risks for the lead in Ardakan and nickel in Meibod and Bahabad were shown to be 1.09 × 10^-3, 1.67 × 10^-1, and 2 × 10^-1, respectively, demonstrating high carcinogenic risk compared to similar standards and studies. The sensitivity analysis suggests high impact of concentration and BW in carcinogenic risk.