Compound health risk assessment of cumulative heavy metal exposure: a case study of a village near a battery factory in Henan Province, China

Health risks of metals in soils and staple foods of the subsistence food gardens in the floodplains of Watut River, Papua New Guinea

The health risks associated with the consumption of staples cultivated in the subsistence food gardens along the Watut River were investigated in Papua New Guinea. Twenty soil samples and twenty-nine samples of staple foods (including banana, taro, sweet potato, and Singapore taro) were collected from the food gardens following a three-day dietary recall survey. The concentration of metals (Cr, Cu, Pb, and Ni) was analyzed in the soil and food samples using Inductively Coupled Plasma Optical Emission Spectrophotometer. The descending order of mean metal concentration in the food garden soils is as follows: Cr > Cu > Ni > Pb. The concentration of Pb in all samples and Cr in 97% of staple foods exceeded the FAO/WHO permissible limits. Approximately 87% of adult consumers of bananas (Musa sp) were found to have estimated Cr and Pb ingestion levels exceeding the permissible daily tolerable intake of metals (0.2 and 0.21 mg day-1, respectively). Hazard index values from the staples analysis indicate that the consumption of bananas (9.40) poses the highest risk of non-carcinogenic effects on adults, followed by taro (7.32), sweet potato (6.13), and Singapore taro (4.30). The consumption of taro is dangerous due to cancer risk associated with the intake of excessive Ni (2.88E-02) and Cr (8.82E-03) in adults and children compared to banana, sweet potato, and Singapore taro. Non-carcinogenic hazards of metal ingestion were found to be pronounced in the younger population, while carcinogenic effects were more serious in adults. Urgent measures must be implemented to protect communities, especially children, from the dangerous effects of heavy metal ingestion through staples in the lower Watut region.

Particulate polycyclic aromatic hydrocarbons in rural households burning solid fuels in Xuanwei County, Southwest China: occurrence, size distribution, and health risks

The study is about the size distribution and health risks of polycyclic aromatic hydrocarbons (PAHs) in indoor environment of Xuanwei, Southwest China particle samples were collected by Anderson 8-stage impactor which was used to gather particle samples to nine size ranges. Size-segregated samples were collected in indoor from a rural village in Xuanwei during the non-heating and heating seasons. The results showed that the total concentrations of the indoor particulate matter (PM) were 757 ± 60 and 990 ± 78 μg/m3 in non-heating and heating seasons, respectively. The total concentration of indoor PAHs reached to 8.42 ± 0.53 μg/m3 in the heating season, which was considerably greater than the concentration in the non-heating season (2.85 ± 1.72 μg/m3). The size distribution of PAHs showed that PAHs were mainly enriched in PMs with the diameter <1.1 μm. The diagnostic ratios (DR) and principal component analysis (PCA) showed that coal and wood for residential heating and cooking were the main sources of indoor PAHs. The results of the health risk showed that the total deposition concentration (DC) in the alveolar region (AR) was 0.25 and 0.68 μg/m3 in the non-heating and heating seasons respectively. Throughout the entire sampling periods, the lifetime cancer risk (R) based on DC of children and adults varied between 3.53 ×10-5 to 1.79 ×10-4. During the heating season, the potential cancer risk of PAHs in adults was significant, exceeding 10-4, with a rate of 96%.

Variations in Cadmium and Lead Bioaccessibility in Wheat Cultivars and Their Correlations with Nutrient Components

To reduce the health risks of exposure to Cd and Pb in wheat, a field experiment was conducted to investigate the differences in Cd and Pb bioaccessibility among the grains of 11 wheat cultivars and their relationships with the nutrient compositions of grains. The grain concentrations (Cd: 0.14-0.56 mg kg-1, Pb: 0.08-0.39 mg kg-1) and bioaccessibility (5.28-57.43% and 0.72-7.72% for Cd and Pb in the intestinal phase, respectively) of Cd and Pb differed significantly among the 11 cultivars. A safe wheat cultivar (Shannong16) with a relatively low health risk and the lowest grain Cd and Pb concentrations was selected. Ca, Mg, phytate, and methionine played key roles in affecting Cd and Pb bioaccessibility in wheat, with Ca and phytate significantly negatively correlated with Cd and Pb bioaccessibility. These findings can be used to optimize the selection strategy for safe wheat cultivars for healthy grain production in Cd-polluted farmland.

Assessing pollution and health risks from chromite mine tailings contaminated soils in India by employing synergistic statistical approaches

Potentially toxic elements (PTEs) contamination in the agricultural soil can generate a detrimental effect on the ecosystem and poses a threat to human health. The present work evaluates the PTEs concentration, source identification, probabilistic assessment of health hazards, and dietary risk analysis due to PTEs pollution in the region of the chromite-asbestos mine, India. To evaluate the health risks associated with PTEs in soil, soil tailings and rice grains were collected and studied. The results revealed that the PTEs concentration (mainly Cr and Ni) of total, DTPA-bioavailable, and rice grain was significantly above the permissible limit in site 1 (tailings) and site 2 (contaminated) as compared with site 3 (uncontaminated). The Free ion activity model (FIAM) was applied to detect the solubility of PTEs in polluted soil and their probable transfer from soil to rice grain. The hazard quotient values were significantly higher than the safe (FIAM-HQ < 0.5) for Cr (1.50E+00), Ni (1.32E+00), and, Pb (5.55E+00) except for Cd (1.43E-03), Cu (5.82E-02). Severity adjustment margin of exposure (SAMOE) results denote that the PTEs contaminated raw rice grain has high health risk [Cr_SAMOE: 0.001; Ni_SAMOE: 0.002; Cd_SAMOE: 0.007; Pb_SAMOE: 0.008] for humans except for Cu. The Positive matrix factorization (PMF) along with correlation used to apportion the source. Self-organizing map (SOM) and PMF analysis identified the source of pollution mainly from mines in this region. Monte Carlo simulation (MCS) revealed that TCR (total carcinogenic risk) cannot be insignificant and children were the maximum sufferers relative to adults via ingestion-pathway. In the spatial distribution map, the region nearer to mine is highly prone to ecological risk with respect to PTEs pollution. Based on appropriate and reasonable evaluation methods, this work will help environmental scientists and policymakers' control PTEs pollution in agricultural soils near the vicinity of mines.

Co-exposure of potentially toxic elements in wheat grains reveals a probabilistic health risk in Southwestern Guizhou, China

Bijie is located at a typical karst landform of Southwestern Guizhou, which presented high geological background values of potentially toxic elements (PTEs). Recently, whether PTE of wheat in Bijie is harmful to human health has aroused people's concern. To this end, the objectives of this study are to determine the concentrations of PTE [chromium (Cr), nickel (Ni), arsenic (As), lead (Pb), cadmium (Cd), and fluorine (F)] in wheat grains, identify contaminant sources, and evaluate the probabilistic risks to human beings. A total of 149 wheat grain samples collected from Bijie in Guizhou were determined using the inductively coupled plasma mass spectrometer (ICP-MS) and fluoride-ion electrode methods. The mean concentrations of Cr, Ni, As, Cd, Pb, and F were 3.250, 0.684, 0.055, 0.149, 0.039, and 4.539 mg/kg, respectively. All investigated PTEs met the standard limits established by the Food and Agriculture Organization except for Cr. For the source identification, Cr and Pb should be originated from industry activities, while Ni, As, and Cd might come from mixed sources, and F was possibly put down to the high geological background value. The non-carcinogenic and carcinogenic health risks were evaluated by the probabilistic approach (Monte Carlo simulation). The mean hazard quotient (HQ) values in the three populations were lower than the safety limit (1.0) with the exception of As (children: 1.03E+00). However, the mean hazard index (HI) values were all higher than 1.0 and followed the order: children (2.57E+00) > adult females (1.29E+00) > adult males (1.12E+00). In addition, the mean carcinogenic risk (CR) values for Cr, As, Pb, and Cd in three populations were all higher than 1E-06, which cannot be negligible. The mean threshold CR (TCR) values were decreased in the order of children (1.32E-02) > adult females (6.61E-03) > adult males (5.81E-03), respectively, all at unacceptable risk levels. Moreover, sensitivity analysis identified concentration factor (C _W ) as the most crucial parameter that affects human health. These findings highlight that co-exposure of PTE in wheat grains revealed a probabilistic human health risk. Corresponding measures should be undertaken for controlling pollution sources and reducing the risks for the local populace.

Seasonal changes of heavy metals and health risk assessment based on Monte Carlo simulation in alternate water sources of the Xinbian River in Suzhou City, Huaibei Plain, China

The urban alternate water source (AWS) is of great significance to the sustainable development of the city, the pollution degree, and source of heavy metals (HMs) in AWS, and whether it will adversely affect human health has received widespread attention. In this study, the urban AWS of Xinbian River in Suzhou City, Huaibei Plain, China, was used as the research object to study the seasonal changes of HMs (As, Cr, Cu, Cd, Pb, and Zn), quantitative identification of pollution sources, and human health risks (HHR). Research results show that the contents of those HMs, except As, are less than the drinking standards limit set by the World Health Organization (WHO), and the contents of As, Cr, and Zn are the largest in summer. The multivariate statistical analysis combined with positive matrix factorization (PMF) model analysis revealed that industrial sources accounted for 44.83%, and agricultural sources accounted for 55.17%. HHR assessment based on Monte Carlo simulation shows that the noncarcinogenic risks of adults and children are in the acceptable range (hazardous ingestion (HI) < 1), and the probability of carcinogenic risk values of children and adults are 95.03% and 38.96%, respectively, which are exceed the acceptable range (1 × 10^-4) recommended by the United States Environment Protection Agency (USEPA). Approximately 30.75% of the carcinogenic risk value of agricultural source HMs to children exceeds the acceptable range (1 × 10^-4). The above research results indicate that the effect of agricultural non-point source pollution on AWS should be prevented.

Determination of potentially toxic metals in depilatory products in the Iranian markets: human health risk assessment

This study aimed to investigate the concentrations of heavy metals, including lead (Pb), cadmium (Cd), chromium (Cr), zinc (Zn), cobalt (Co), and arsenic metalloid (As), to assess their health risks in the popular depilatory products of the Iranian markets. Twenty-one samples of 7 popular brands of depilatory products, inclusive of cream and powder, were examined. Selected elements were measured by inductively coupled plasma optical emission spectrometry (ICP-OES) using the appropriate procedure for acid digestion and the measurement of heavy metal contents. The differences in heavy metal concentrations were investigated according to the type of product, brand, country of production, and product price using t test and one-way analysis of variance and post hoc Tukey test. Finally, carcinogenic and non-carcinogenic risk assessments were calculated for the studied elements. The results showed that Pb (5.46±2.30 mg/kg) and Co (0.16±0.69 mg/kg) had the highest and lowest concentrations in these products, respectively. In general, the concentration of heavy metals in depilatory creams was less than the concentration of elements in depilatory powders and less than the maximum allowable limits as defined by the Institute of Standards and Industrial Research of Iran (ISIRI). There was a direct and significant relationship between the concentration of heavy metals in depilatory powders and the product's price. Moreover, the amount of As in one of the brands of depilatory powder was determined to exceed the standard value (2 mg/kg). Also, hazard index (HI) and lifetime cancer risk (LCR) were below 1 and 10-6, respectively, which indicated that this mentioned heavy metal had no probable non-carcinogenic and carcinogenic risks for consumers. According to this study, it was evident that the chances of cancer and non-cancer risk using depilatory products were unlikely, but continuous use can be harmful due to the excessive accumulation of these heavy metals.

Investigations of Metal Pollution in Road Dust of Steel Industrial Area and Application of Magnetic Separation

Pollution characteristics and ecological risks for metals in non-magnetic and magnetic road dust from steel industrial areas were investigated by applying a magnetic separation method. Metal (except for Al, Li, Ti, As, and Sb) concentrations in the magnetic road dust were 1.2 (Sn) to 7.8 (Fe) times higher than those in the non-magnetic road dust. For the magnetic road dust, the geo-accumulation index revealed a strongly to extremely polluted status for Cr, Zn, Cd, and Sb, a strongly polluted status for Mn, Cu, and Pb, and a moderately to strongly polluted status for Fe, Ni, Mo, and Hg. This result indicates that the dominant metal pollution sources of road dust in industrial areas were the traffic activities of heavy-duty vehicles. The mean content of magnetic particles accounted for 44.7% of the total road dust. The metal loadings in the magnetic road dust were 86% (Fe), 77% (Cr), 67% (Mn), 86% (Ni), 76% (Cu), 72% (Zn), 64% (Mo), and 62% (Cd), respectively. Removal of the magnetic fraction from road dust using magnetic separation techniques not only reduces metal contamination but can also improve effective road cleaning strategies or reduce waste generation.

Effects of long-term discharge of acid mine drainage from abandoned coal mines on soil microorganisms: microbial community structure, interaction patterns, and metabolic functions

More than twenty abandoned coal mines in the Yudong River Basin of Guizhou Province have discharged acid mine drainage (AMD) for a long time. The revelation of microbial community composition, interaction patterns, and metabolic functions can contribute to a better understanding of such ecosystems, which in its turn can be helpful in the development of strategies aiming at the ecological remediation of AMD pollution. In this study, reference and contaminated soil samples were collected along the AMD flow path for high-throughput sequencing. Results showed that the long-term AMD pollution promoted the evolution of γ-Proteobacteria, and the acidophilic iron-oxidizing bacteria Ferrovum (relative abundance of 15.50%) and iron-reducing bacteria Metallibacterium (9.87%) belonging to this class became the dominant genera. Co-occurrence analysis revealed that the proportion of positive correlations among bacteria increased from 51.02 (reference soil) to 75.16% (contaminated soil), suggesting that acidic pollution promotes the formation of mutualistic interaction networks of microorganisms. Metabolic function prediction (Tax4Fun) revealed that AMD contamination enhanced microbial functions such as translation, repair, and biosynthesis of peptidoglycan and lipopolysaccharide, etc., which may be an adaptive mechanism for microbial survival in extremely acidic environment. In addition, acidic pollution promoted the high expression of nitrogen-fixing genes in soil, and the discovery of autotrophic nitrogen-fixing bacteria such as Ferrovum highlights the possibility of using this taxon for bioremediation of AMD pollution.

Characteristics of Potentially Toxic Elements, Risk Assessments, and Isotopic Compositions (Cu-Zn-Pb) in the PM10 Fraction of Road Dust in Busan, South Korea

The pollution status of ten potentially toxic elements (PTEs), isotopic compositions (Cu, Zn, Pb), and the potential ecological risk posed by them were investigated in the PM10 fraction of road dust in Busan Metropolitan city, South Korea. Enrichment factors revealed extremely to strongly polluted levels of Sb, Cd, Zn, Pb, and Cu in the PM10 fraction of road dust, with Sb levels being the highest. Statistical analyses showed that the major cause for contamination with PTEs was non-exhaust traffic emissions such as tire and brake wear. Cu and Zn isotopic compositions of road dust were related to traffic-related emission sources such as brake and tires. Pb isotopic compositions were close to that of road paint, indicating that Pb was a different source from Cu and Zn in this study. No significant health risk was posed by the PTEs. Taking into account the total length of road in Busan, a high quantity of PTEs in road dust (PM10) can have serious deleterious effects on the atmospheric environment and ecosystems. The results of metal concentrations and isotopic compositions in road dust will help identify and manage atmospheric fine particle and coastal metal contamination derived from fine road dust.

Occurrence and dietary exposure of heavy metals in marketed vegetables and fruits of Shandong Province, China

The contamination of heavy metals in vegetables and fruits is a serious threat to food safety and human health. The present study was designed to investigate the occurrence and dietary exposure of lead (Pb), arsenic (As), cadmium (Cd), and mercury (Hg) in vegetables and fruits in Shandong Province, China. Results demonstrated that the mean level of total heavy metals was 30.25 µg/kg. The most frequently found heavy metal was Cd (69.2%) with a mean value of 11.54 µg/kg. The mean exposure values of Pb, As, Cd, and Hg in vegetables were 0.052, 0.045, 0.038, and 2.40 × 10-3 µg/kg bw/day, respectively. Moreover, the calculated hazard quotient (HQ) values of mean levels for these four heavy metals were all less than 1, indicating the health risk of heavy metal exposure caused by vegetable consumption was low. This study has displayed baseline information on heavy metal contamination in vegetables and fruits, which can provide useful data support for the formulation of relevant standards and government management.

Remediation of chromium- and fluoride-contaminated groundwater by immobilized Citrobacter sp. on a nano-ZrO2 hybrid material

To effectively address excessive SO₄^2-, Cr(VI), total chromium and F^- in the groundwater of acidic mining areas, a facultative anaerobic bacterium, Citrobacter, with sulfate-reducing properties, tolerance to hexavalent chromium and the ability to reduce Cr(VI) to Cr(III) was isolated and domesticated. Based on microbial immobilization technology, a nano-ZrO₂ polyacrylamide hybrid material was prepared as an embedding agent to form nano-ZrO₂ polyacrylamide Citrobacter (ZPC) particles. ZPC was microscopically characterized, and the removal performance and mechanism of ZPC for SO₄^2-, Cr(VI), total chromium and F^- in groundwater were analyzed. The results of single-factor tests showed that the optimal reaction conditions included a reaction temperature of 35°C, Citrobacter dosage of 35% (volume ratio) in the particles and hybrid material dosage of 300 mL; under these conditions, the removal rates of SO₄^2-, Cr(VI), total chromium and F^- were 70.5%, 100%, 100% and 93.3%, respectively, and the pH value increased from 4.6 to 8.07. On this basis, the effects of the reaction layer type, influent hydraulic load and influent concentration on the removal efficiency of polluted groundwater were studied through dynamic experiments. The experimental results showed that ZPC particles were better than Citrobacter as a reaction layer; the optimal influent hydraulic load was 3.0 m³/(m²·d); the selectivity of ZPC particles to anions and anionic groups was different; and the order of adsorption selectivity was F^- > Cr(VI) > SO₄^2-.

Evaluating heavy metals contamination in soil and vegetables in the region of North India: Levels, transfer and potential human health risk analysis

This study determined the heavy metals (HMs) accumulation in different vegetables in different seasons and attributed a serious health hazard to human adults due to the consumption of such vegetables in Jhansi. The total amounts of zinc (Zn), lead (Pb), nickel (Ni), manganese (Mn), copper (Cu), cobalt (Co), and cadmium (Cd) were analysed in 28 composite samples of soil and vegetables (Fenugreek, spinach, eggplant, and chilli) collected from seven agricultural fields. The transfer factor (TF) of HMs from soil to analysed vegetables was calculated, and significant non-carcinogenic health risks due to exposure to analysed heavy metals via consumption of these vegetables were computed. The statistical analysis involving Principal Component Analysis (PCA) and Pearson's correlation matrix suggested that anthropogenic activities were a major source of HMs in the study areas. The target hazard quotient of Cd, Mn, and Pb for fenugreek (2.156, 2.143, and 2.228, respectively) and spinach (3.697, 3.509, 5.539, respectively) exceeded the unity, indicating the high possibilities of non-carcinogenic health risks if regularly consumed by human beings. This study strongly suggests the continuous monitoring of soil, irrigation water, and vegetables to prohibit excessive accumulation in the food chain.