Potential risk effect from elevated levels of soil heavy metals on human health in the Niger delta

Assessment of heavy metal(oid) pollution and related health risks in agricultural soils surrounding a coal gangue dump from an abandoned coal mine in Chongqing, Southwest China

The coal gangue dump may introduce heavy metal(oid)s (HMs) into surrounding agricultural soils, posing potential health risks to nearby communities. This study evaluated heavy metal(oid) pollution in agricultural soils adjacent to a gangue dump at an abandoned coal mine in Chongqing, Southwest China. The concentrations of HMs (As, Cd, Cr, Cu, Ni, Pb, and Zn) were quantified using ICP-MS, and the contamination status was assessed using the Geoaccumulation Index (Igeo), Contamination Factor (CF), Pollution Load Index (PLI), and Potential Ecological Risk Index (RI). Heavy metal(oid) contamination was detected in soils across a depth of 0-30 cm, particularly pronounced in the topsoil layer (0-10 cm and 10-20 cm depths). Cu emerged as the predominant contaminant across all examined depths, with average Igeo values of 1.20, 1.21, and 1.16 for the 0-10 cm, 10-20 cm, and 20-30 cm depths, respectively, indicating moderate contamination. The CF for Cu was 3.55, 3.55, and 3.50 for these respective depths, classifying it as considerable contamination. The PLI values ranged from 1.61 to 2.50, with a mean value of 2.12, indicating overall contamination. The ecological risk assessment indicated that the soil's ecological risk was low at all depths. Cd was the major contributor to the RI, accounting for 48%, 47%, and 42% at 0-10 cm, 10-20 cm, and 20-30 cm depths, respectively. Health risk assessments revealed significant non-carcinogenic risks to children (mean HI = 1.30) and unacceptable carcinogenic risks to both adults and children (mean TCR = 3.26 × 10-4 and 1.53 × 10-3, respectively). This study underscores the critical need for comprehensive risk assessments using multiple indicators to prioritize remediation efforts for HMs, providing a scientific basis for effective environmental management and public health protection in the Three Gorges Reservoir Area.

Spatial distribution of heavy metal abundance at distance gradients of roadside agricultural soil from the busiest highway in Bangladesh: A multi-index integration approach

Bangladesh is currently experiencing significant infrastructural development in road networking system through the construction or reconstruction of multiple roads and highways. Consequently, there is a rise in traffic intensity on roads and highways, along with a significant contamination of adjacent agricultural soils with heavy metals. The purpose of this study was to evaluate the ecological risk, health risk and the abundance of seven heavy metals (Cu, Mn, Pb, Cd, Cr, As, and Ni) in three distance gradients (0, 300, and 500 m) of agricultural soil along the Dhaka-Chattogram highway. The concentration of heavy metals was measured with an Atomic Absorption Spectrophotometer (AAS) on a total of 36 soil samples that were taken from 12 different sampling sites. Based on the findings, Cd had a high contamination factor for all distance gradients, whereas Cr had a moderate contamination factor in 67% of the study areas. According to the Pollution Load Index (PLI), Cd, Cr, and Pb were the predominant pollutants. Principal component analysis (PCA) result shows these metals mainly came from anthropogenic sources. The considerable positive correlations between Cu-Pb, Cu-Cd, Pb-Cd, and Cr-Ni all pointed to shared anthropogenic origins. As per Potential Ecological Risk Assessment (PERI) analysis, Pb, Cd, Cr, and Ni each contribute significantly and pose a moderate threat. The Target Hazard Quotient (THQ) values for all pathways of exposure to Pb and Cr in soils were more than 1, which would pose a significant risk to human health in the following order: THQadult female > THQadult male > THQchildren. This study will help to evaluate the human health risk and develop a better understanding of the heavy metal abundance scenario in the agricultural fields adjacent to this highway.

Engaging One Health in Heavy Metal Pollution in Some Selected Nigerian Niger Delta Cities. A Systematic Review of Pervasiveness, Bioaccumulation and Subduing Environmental Health Challenges

The Niger Delta environment is under serious threat due to heavy metal pollution. Many studies have been conducted on the heavy metal contamination in soils, water, seafood and plants in the Niger Delta ecosystem. However, there is a lack of clear understanding of the health consequences for people and strategies for attaining One Health, and a dispersion of information that is accessible. The study focused on investigating the contamination levels, distributions, risks, sources and impacts of heavy metals in selected regions of the Niger Delta. Prior studies revealed that the levels of certain heavy metals, including Cd, Pb, Cu, Cr, Mn, Fe and Ni, in water, sediment, fish and plants in most Niger Delta ecosystems were higher than the acceptable threshold attributed to various anthropogenic stressors. In the reviewed Niger Delta states, ecosystems in Rivers state showed the highest concentrations of heavy metals in most sampled sites. Groundwater quality was recorded at concentrations higher than 0.3 mg/L World Health Organization drinking water guideline. High concentrations of copper (147.915 mg/L) and zinc (10.878 mg/L) were found in Rivers State. The heavy metals concentrations were greater in bottom-dwelling organisms such as bivalves, gastropods and shrimp than in other fishery species. Heavy metal exposure in the region poses risks of communicable and non-communicable diseases. Diverse remediation methods are crucial to reduce contamination levels, but comprehensive strategies and international cooperation are essential to address the health hazards. Actively reducing heavy metals in the environment can achieve One Health objectives and mitigate disease and economic burdens.

Effect of waste-derived soil amendments on mitigating leaching impacts from municipal solid waste incineration (MSWI) ash

This study explores modifying a sandy soil with a low solid to liquid partitioning coefficient (Kd) by adding amendments including iron-rich industrial slag byproducts and biochars, which contain sorption sites for trace metals present in MSWI ash leachate (notably Sb, cited as a concern for reuse applications). Kd values for Sb were determined for the sandy soil to be as low as 1.6 ± 0.1 L/kg. With amendments, Kd values varied from 1.4 ± 0.2 L/kg for combined ash leachate exposed to a blend of sandy soil and 20% iron slag, to 990 L/kg for combined ash leachate exposed to a blend of sandy soil and 20% magnetic solids. A blend of 20% magnetic solids showed orders of magnitude increase beyond 100% sandy soil. The biochars showed limited capacity to reduce leached Sb in the ash-derived leachate, which is likely due to negative surface charges of the biochars and Sb at basic pH. A risk assessment (US EPA IWEM) performed using experimental Kd for each blend suggests that using soil amendments could reduce leached concentrations at points of concern, which could open additional avenues for ash reuse.

Concentrations and health risk appraisal of heavy metals and volatile organic compounds in soils of automobile mechanic villages in Ogun State, Nigeria

This report presents the findings of the concentrations, distributions and health risks assessment of heavy metals (HMs) and volatile organic compounds (VOCs) in topsoils of two typical automobile mechanic villages (MVs) situated within Ogun State, Nigeria. One of the MVs is located in basement complex terrain (Abeokuta), while the second is in the sedimentary formation (Sagamu). Ten composite samples were collected at depth of 0-30 cm with the aid of soil auger from spent oil-contaminated spots within the two MVs. The chemical parameters of interest were Pb, Cd, benzene, ethylbenzene, toluene, total petroleum hydrocarbon (TPH) as well as oil and grease (O&G). In addition, soil pH, cation exchange capacity (CEC), electrical conductivity (EC) and particle size distribution were also evaluated in order to find out their impacts on assessed soil pollutants. Results revealed that the soils in both MVs are of sandy loam texture, slight acidic to neutral pH, mean CEC < 15 cmol/kg and mean EC > 100 μS/cm. The mean concentration of each of analyzed HMs and VOCs in soils from the two MVs was < 5 mg/kg, while the mean values of TPH and O&G content were > 50 mg/kg. The mean Cd values in soils of both MVs were higher than the national soil screening level of 0.8 mg/kg, but lower than the Canadian and Italian guidelines. There is no significant correlation between each of HMs/VOCs and any of assessed soil physicochemical variables. The non-cancer risk expressed in terms of hazard index (HI) was > 1 via oral ingestion route for adults and children at the two MVs, indicating adverse non-carcinogenic health risk. The HI > 1 value was obtained for adults only through the dermal absorption pathway in Abeokuta MV. However, HI values for the two age groups at the two MVs via inhalation route were < 1, indicating no likelihood of any non-carcinogenic effects via the breathing exposure. The potential of non-cancer risk via oral ingestion route in both MVs was derived from the contributive ratios of HMs and VOCs in the order: Cd > benzene > Pb > toluene. The carcinogenic risk (CR) values due to ingested Cd, benzene and Pb for both age groups at the two MVs exceed the safe limit range of 10-6 to 10-4. Cadmium, benzene and lead made considerable contributions to the estimation of CR through dermal exposure for adults only in Abeokuta MV. The CR values via inhalation pathway for adults and children in both MVs were within the threshold range. Artisans and children should circumvent accidental ingestion of contaminated soils in addition to wearing of protective clothes during routine vehicle maintenance activities.

Spatial distribution, sources and health risk assessment of heavy metals in topsoil around oil and natural gas drilling sites, Andhra Pradesh, India

Soils are usually the interface between human activity and environmental components that must be conserved and protected. As a result of rising industrialization and urbanization, activities such as exploration and extraction operations lead to the release of heavy metals into the environment. This study presents distribution of six heavy metals (As, Cr, Cu, Ni, Pb and Zn) in 139 top soil samples collected in and around oil and natural gas drilling sites at a sampling density of 1 site/12 km2. The results indicated the concentration ranged from 0.1 to 16 mg/kg for As, 3-707 mg/kg for Cr, 7-2324 mg/kg for Cu, 14-234 mg/kg for Ni, 9-1664 mg/kg for Pb, and 60-962 mg/kg for Zn. The contamination of soil was estimated on the basis of Index of geo accumulation (Igeo), enrichment factor (Ef), and contamination factor (Cf). Further, spatial distribution pattern maps indicated that the pollution levels for Cu, Cr, Zn, and Ni were higher around drilling sites of the study area relative to other regions. Using exposure factors for the local population and references from the USEPA's integrated database, potential ecological risk indices (PERI) and health risk assessments were made. The hazard index (HI) values of Pb (in adults) and Cr, Pb (in children) exceeded the recommended limit of HI = 1, indicating the non-carcinogenic risks. Total carcinogenic risk (TCR) calculations revealed Cr (in adults) and As, Cr (in children) levels in soils exceeded the threshold value of 1.0E - 04, indicating significant carcinogenic risk due to high metal concentrations in the study area. These results may assist in determining the soil's present state and its effect due to extraction strategies used during drilling process and initiate few remedial techniques, particularly for proper management strategies in farming activities to decrease point and non-point source of contamination.

Priority planting area planning for cash crops under heavy metal pollution and climate change: A case study of Ligusticum chuanxiong Hort

INTRODUCTION

Soil pollution by heavy metals and climate change pose substantial threats to the habitat suitability of cash crops. Discussing the suitability of cash crops in this context is necessary for the conservation and management of species. We developed a comprehensive evaluation system that is universally applicable to all plants stressed by heavy metal pollution.

METHODS

The MaxEnt model was used to simulate the spatial distribution of Ligusticum chuanxiong Hort within the study area (Sichuan, Shaanxi, and Chongqing) based on current and future climate conditions (RCP2.6, RCP4.5, RCP6.0, and RCP8.5 scenarios). We established the current Cd pollution status in the study area using kriging interpolation and kernel density. Additionally, the three scenarios were used in prediction models to simulate future Cd pollution conditions based on current Cd pollution data. The current and future priority planting areas for L. chuanxiong were determined by overlay analysis, and two levels of results were obtained.

RESULTS

The results revealed that the current first- and secondary-priority planting areas for L. chuanxiong were 2.06 ×10³ km² and 1.64 ×10⁴ km², respectively. Of these areas, the seven primary and twelve secondary counties for current L. chuanxiong cultivation should be given higher priority; these areas include Meishan, Qionglai, Pujiang, and other regions. Furthermore, all the priority zones based on the current and future scenarios were mainly concentrated on the Chengdu Plain, southeastern Sichuan and northern Chongqing. Future planning results indicated that Renshou, Pingwu, Meishan, Qionglai, Pengshan, and other regions are very important for L. chuanxiong planting, and a pessimistic scenario will negatively impact this potential planting. The spatial dynamics of priority areas in 2050 and 2070 clearly fluctuated under different prediction scenarios and were mainly distributed in northern Sichuan and western Chongqing.

DISCUSSION

Given these results, taking reasonable measures to replan and manage these areas is necessary. This study provides. not only a useful reference for the protection and cultivation of L. chuanxiong, but also a framework for analyzing other cash crops.

Anthropic impact on soil heavy metal contamination in riparian ecosystems of northern Algeria

The aim of this research was to highlight the impact of urbanization and agriculture on soil quality, mainly by focusing on heavy metal accumulation (Cd, Cu, Fe, Mn, Ni, Pb and Zn) in the fragile riparian ecosystems of the Medjerda river (Souk-Ahras, Algeria). This study was performed in three cultivated soils (0-10, 10-20, 20-60 cm depth) along an increasing gradient of anthropogenic pressure in non-urban (NU), peri-urban (PU) and urban areas (U). Geo-accumulation index (Igeo), Enrichment factor (EF), Pollution load index (PLI) and Potential ecological risk index (RI) were calculated, as well as the potential non-carcinogenic risk for humans (HI). Additionally, to corroborate the role of Bufo spinosus D. as biosentinel, a skin biopsy was performed to quantify the concentration of heavy metals in both terrestrial and aquatic ecosystems. The results showed that when compared to NU, U and PU areas were richer in heavy metals. In particular, Igeo-Cd displayed strongly contaminated soil in U (>3), EF showed high enrichment of heavy metals (>2) for all the soils except for Ni, PLI presented no contamination for all (<1) while RI was significantly higher in U (>300), denoting a strong impact of heavy metals on soil quality. However, HI was below 1 for all the studied areas, although the highest values were related to U and PU. The skin biopsy showed the highest values for Cu, Fe and Pb in PU (0.328, 0.713 and 0.524 mg kg^-1, respectively) similarly to trends observed in the soil of that area. This study shed light on the rising pollution of heavy metals due to urbanization and agricultural input in these fragile ecosystems where Bufo spinosus D. plays the role of potential bio-indicator for environmental pollution.

Contamination Assessment and Potential Human Health Risks of Heavy Metals in Urban Soils from Grand Forks, North Dakota, USA

Heavy metal (HM) pollution of soil is an increasingly serious problem worldwide. The current study assessed the metal levels and ecological and human health risk associated with HMs in Grand Forks urban soils. A total 40 composite surface soil samples were investigated for Mn, Fe, Co, Ni, Cu, Zn, As, Pb, Hg, Cr, Cd and Tl using microwave-assisted HNO3-HCl acid digestion and inductively coupled plasma mass spectrometry (ICP-MS) analysis. The enrichment factor (EF), contamination factor (CF), geoaccumulation index (Igeo), ecological risk and potential ecological risk index were used for ecological risk assessment. The park soils revealed the following decreasing trend for metal levels: Fe > Mn > Zn > Cr > Ni > Cu > Pb > As > Co > Cd > Tl > Hg. Based on mean levels, all the studied HMs except As and Cr were lower than guideline limits set by international agencies. Principal component analysis (PCA) indicated that Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Pb, Cr and Tl may originate from natural sources, while Hg, Pb, As and Cd may come from anthropogenic/mixed sources. The Igeo results showed that the soil was moderately polluted by As and Cd and, based on EF results, As and Cd exhibited significant enrichment. The contamination factor analysis revealed that Zn and Pb showed moderate contamination, Hg exhibited low to moderate contamination and As and Cd showed high contamination in the soil. Comparatively higher risk was noted for children over adults and, overall, As was the major contributor (>50%), followed by Cr (>13%), in the non-carcinogenic risk assessment. Carcinogenic risk assessment revealed that As and Cr pose significant risks to the populations associated with this urban soil. Lastly, this study showed that the soil was moderately contaminated by As, Cd, Pb and Hg and should be regularly monitored for metal contamination.

Spatial distribution and ecological risk assessment of heavy metals in alpine grasslands of the Zoige Basin, China

Heavy metals elements are not only related to the functions of ecosystems but also affect human health. To understand the characteristics of heavy metals in the topsoil of the Zoige alpine basin, a total of 252 grass and topsoil samples were collected in May and September 2014. The results showed that only Cd and Pb highly exceeded their background values (BV); in May and September, Cd was 2.02- and 1.55-fold higher than its BV, respectively, and Pb was 2.35- and 2.17-fold above its BV, respectively. The sources of Cd and Pb were homologous. In addition, the comprehensive potential ecological risk index was less than 150, indicating that heavy metal pollution in the study area is currently low. The spatial interpolation indicated that Cd and Pb pollution might be related to tourism and transportation, but the low biological absorption coefficient for all heavy metals showed that heavy metal absorption ability of forage was low and would not impact yak breeding. Finally, the soil was lightly contaminated by Cd and Pb due to the rapid development of the animal husbandry and tourism. The spatial variation of heavy metal in the basin is dominated by structural factors, and the random factors also have an effect on spatial distribution of As, Cd, Cu and Ni. The random factors such as overgrazing can exert an influence on physical structure and the circulation of nutrient substances of meadow soil through livestock grazing and trampling, ultimately affecting the content and distribution of soil heavy metals.

Receptor model-based sources and risks appraisal of potentially toxic elements in the urban soils of Bangladesh

Rapid urbanization and industrial development have prompted potentially toxic elements (PTEs) in urban soil in Bangladesh, which is a great concern for ecological and public health matters. The present study explored the receptor-based sources, probable human health and ecological risks of PTEs (As, Cd, Pb, Cr, Ni, and Cu) in the urban soil of the Jashore district, Bangladesh. The USEPA modified method 3050B and atomic absorption spectrophotometers were used to digest and evaluate the PTEs concentration in 71 soil samples collected from eleven different land use areas, respectively. The concentration ranges of As, Cd, Pb, Cr, Ni, and Cu in the studied soils were 1.8-18.09, 0.1-3.58, 0.4-113.26, 0.9-72.09, 2.1-68.23, and 3.82-212.57 mg/kg, respectively. The contamination factor (CF), pollution load index (PLI), and enrichment factor (EF) were applied to evaluate the ecological risk posed by PTEs in soils. Soil quality evaluation indices showed that Cd was a great contributor to soil pollution. The PLI values range was 0.48-2.82, indicating base levels to continuous soil degradation. The positive matrix factorization (PMF) model showed that As (50.3 %), Cd (38.8 %), Cu (64.7 %), Pb (81.8 %) and Ni (47.2 %) were derived from industrial sources and mixed anthropogenic sources, while Cr (78.1 %) from natural sources. The highest contamination was found in the metal workshop, followed by the industrial area, and brick filed site. Soil from all land use types revealed moderate to high ecological risk after evaluating probable ecological risks, and the descending order of single metal potential ecological risk was Cd > As > Pb > Cu > Ni > Cr. Ingestion was the primary route of exposure to potentially toxic elements for both adults and children from the study area soil. The overall non-cancer risk to human health is caused by PTEs for children (HI=0.65 ± 0.1) and adults (HI=0.09 ± 0.03) under USEPA safe limit (HI>1), while the cancer risks from exclusively ingesting As through soil were 2.10E-03 and 2.74E-04 for children and adults, respectively, exceeding the USEPA acceptable standard (>1E-04).

Spatial Distribution and Assessment of the Human Health Risks of Heavy Metals in a Retired Pharmaceutical Industrial Area, Southwest China

Heavy metals pollution in pharmaceutical industries received increasing attention. A total of 94 soil samples were collected in this study. Results showed the mean contents of Hg, Cd, As, Pb, Ni and Cu were 0.21, 0.26, 9.59, 55.06, 51.52 and 50.81 mg·kg^-1, respectively. The spatial distribution of metals in topsoil largely attributed to the pharmaceutical production process. The distribution of Hg and As were related to the production of medical absorbent cotton. While Ni was related to the fuel supply of Ni-rich coal. Cr, Cu and Pb mainly distributed in the process which they were used as catalysts. The vertical migration of metals was complex in soil. To a great extent, it was related to the texture of the soil and the properties of metals in this filed. The total non-cancer and cancer human health risk were within the limits of USEPA (10^-6 a^-1). This demonstrated the health risks of individual's exposure to heavy metals in this factory was acceptable.

Spatial distribution, sources and risk assessment of potentially toxic elements contamination in surface soils of Yellow River Delta, China

The contamination status and ecological risk of soil potentially toxic elements (PTEs) in Yellow River Delta (YRD) are still poorly understood. Thirty surface soil samples were collected in YRD, determined for contents of PTEs, and assessed using four kinds of proxies. Results indicated that PTEs contents basically met the Environmental Quality Standard for Soils, and spatial heterogeneity of PTEs was not distinctive except for a few sampling sites. Results of geo-accumulation index (I_geo) and enrichment factor (EF) indicated significant enrichment of As and Sb in YRD. The multivariate analysis results distinguished the possible sources of these PTEs and demonstrated that sources of Ag, As, Cd, Cu, Pb, Sb and Zn could be influenced by anthropogenic activities (industrial and agricultural sources). Moreover, Ni, Cr and As had relatively high contributions to sum of toxicity units (ΣTUs). This study provides basic information for understanding soil PTEs contamination status of YRD.

Countrywide Spatial Variation of Potentially Toxic Element Contamination in Soils of Turkey and Assessment of Population Health Risks for Nondietary Ingestion

Countrywide surface soil concentrations of potentially toxic elements (PTEs) in Turkey were reviewed in the Web of Science database. A total of 93 papers were investigated to compose a PTE dataset for determining spatial variations and estimating exposure and health risks. Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were selected as PTEs in surface soil. A compiled PTE concentration dataset was used to estimate chronic toxic risks (CTRs) and carcinogenic risks (CRs) according to the deterministic and probabilistic approaches. While the CTR and CR levels of age and sex groups were estimated using a deterministic approach, population risks were estimated using a probabilistic approach. CTR and CR levels in lower age groups and female sex groups were estimated to be higher than those in higher age groups and associated male sex groups. The average CTR levels of the nondietary ingestion of As-containing soil in <11 year age groups were near/just above the threshold level, while As-associated average CR levels of adults and other age groups were estimated to be in the acceptable risk range (10^-6 < CR < 10^-5) and low priority risk range (10^-5 < CR < 10^-4), respectively. As-, Cr(VI)-, and Pb-associated upper-bound CR levels of the Turkish population were simulated to be 5.14 × 10^-4, 6.23 × 10^-5, and 2.34 × 10^-6, respectively. Health risk models show the significance of As in both chronic toxic and carcinogenic effects.

Environmental impact and health risk assessment of potentially toxic metals emanating from different anthropogenic activities related to E-wastes

The global desire for modernization through technology has thrown up a major disposal challenge for e-wastes, especially in low-economic countries. This study assessed the environmental impacts and possible health risks of potentially toxic metals emanating from poorly managed e-wastes across three main representative sites in southwest Nigeria. Soil samples were collected from three major cities in Southwestern Nigeria and analyzed for As, Cd, Pb, Cu, Cr, Ni and Zn. Pollution assessments were done using indices including contamination factor (C_f), pollution load index (PLI) and potential ecological risk index (PERI) coupled with evaluation of non-cancer and cancer health risks. Results showed enrichment of the local soil with metals due to e-wastes related activities, with an elevated level of C_f (>6), revealing that the soils around the e-waste dumpsites were severely contaminated. In addition, the assessment of individual metal potential ecological risk index (Eⁱ_f) showed a high level of potential ecological risk for Cd (Eⁱ_f >320) at all the sites while As, Pb, Cu and Ni exhibited high ecological risk at the sites, especially at topsoil layer. Furthermore, the study established varying potentials for carcinogenic health risks for residents around the dumpsites, such that while a negligible risk index occurred for Cd and Ni (RI < 10⁻⁶), the risk is tolerable for Pb (0⁻⁶ < RI < 10^–4) but within cancer-development range for As and Cr (RI > 10⁻⁴). The study concluded that poorly managed e-wastes in the area poses significant threats to the health of humans and the entire ecosystem. Further study is recommended to identify similar e-waste dumpsites at regional and national – scales for sustainable restoration and improved e-waste management.

Effects of indoor air pollution on tribal community in rural India and health risk assessment due to domestic biomass burning: a realistic approach using the lung deposition model

Indoor air pollution from the combustion of biomass fuel and associated health risks is a critical issue in developing countries. Concentrations of PM2.5 and PM10 are measured in Birbhum, West Bengal, during 2017-2018. PM2.5-bound elemental concentrations of twelve metals are determined in rural kitchens. The results showed higher toxicological risks in BMF (1.15) than the LPG users (0.14). The risk of non-carcinogenic exposure related with dermal contact and ingestion was observed in the acceptable limits (HQ < 1) for all age groups, and the risk associated with inhalation exposure from Cr, Ni, As, and Mn exceeded the acceptable limit. Results also suggest that carcinogenic risks from ingestion and dermal contact are within the acceptable limit (1 × 10-4-1 × 10-6) except Cr and As which were found to exceed the range. The deposition flux (Dφ) for multiple metals in the head airway region, tracheobronchial region, and alveolar regions was found to be higher in teenagers as compared to other groups, whereas the value was lower in infants. Further, it was notified from the Dφ that the metals could pass through the head airways and harm the tracheobronchial tree and alveolar region, increasing the risk of human health.

Probabilistic health risk assessment for residents exposed to potentially toxic elements near typical mining areas in China

Public health problems caused by toxic elements in mining areas have always been an important topic worldwide. However, existing studies have focused on single exposure routes and common toxic elements, which might underestimate the risks faced by residents. In this study, three typical mining areas in central China were selected to assess the health risks of 14 potentially toxic elements through five exposure routes using Monte Carlo simulations. The results indicated that the 95th percentile non-carcinogenic risk values to humans via rice and vegetable ingestion ranged from 9.8 to 26.0 and 6.2 to 19.0. The corresponding carcinogenic risks ranged from 1.4E-2 to 6.3E-2 and from 2.9E-3 to 2.3E-2, respectively. Therefore, residents face serious health risks. Multi-element analysis showed that cadmium (Cd), boron (B), and arsenic (As) were the main contributors to rice non-carcinogenicity, whereas Cd and nickel (Ni) were the main elements of rice carcinogenicity. B and lead (Pb) played an essential role in the non-carcinogenesis of vegetables, and B, Ni, and Cd played an essential role in carcinogenesis. Accidental ingestion is the main route of soil exposure. In these three areas, the probability of non-carcinogenic risk faced by adults was 40%, 0%, and 1%, respectively, while the probabilities for children were 100%, 62%, and 83%, respectively. Regarding carcinogenicity, the risk for both adults and children was up to 100%. This study emphasizes the overall health risks in polluted areas via multi-route and multi-element analysis. This conclusion is helpful to comprehensively assess the potential health risks faced by residents in mining areas and provide baseline data support and a scientific basis for formulating reasonable risk control measures.

Risk Assessment and Potential Analysis of the Agricultural Use of Sewage Sludge in Central Shanxi Province

The agricultural use of sewage sludge has become an economic disposal method used worldwide. However, heavy metals contained in sewage sludge have become the crucial limiting factors for this way of disposal. This study showed that regulatory limit values are not enough to determine whether sewage sludge is suitable for agricultural use; risk assessment and potential analysis should be applied. Correlation analysis and hierarchical cluster analysis (HCA) should also be performed to identify heavy metals' sources and show their influence on sewage sludge utilization. Samples were collected from 13 wastewater treatment plants (WWTPs) located in central Shanxi Province. Results indicated that the mean contents of heavy metals in sewage sludge were all less than the limit threshold of China. According to the monomial potential ecological risk coefficient (), the agricultural use of sewage sludge had low ecological risks for all heavy metals, except for Hg and Cd. Based on the potential ecological risk index (RI), only three stations had moderate risk, other nine stations all had higher potential risk. The mean potentials by all heavy metals were all beyond 10 years, which is the limit of the maximum application time specified by China. Combining all heavy metals, only one station's potential was less than 10 years. Although the contents of heavy metals were all within the threshold values, large quantities of sewage sludge are not suitable for agricultural use. Coal-related industries, which were the main sources of Hg and Cd, greatly affected the agricultural use of sewage sludge.

Ranking of Basin-Scale Factors Affecting Metal Concentrations in River Sediment

River sediments often contain potentially harmful pollutants such as metals. Much research has been conducted to identify factors involved in sediment concentrations of metals. While most metal pollution studies focus on smaller scales, it has been shown that basin-scale parameters are powerful predictors of river water quality. The present study focused on basin-scale factors of metal concentrations in river sediments. The study was performed on the contiguous USA using Random Forest (R.F.) to analyze the importance of different factors of the metal pollution potential of river sediments and evaluate the possibility of assessing this potential from basin characteristics. Results indicated that the most important factors belonged to the groups Geology, Dams, and Land cover. Rock characteristics (contents of K2O, CaO, and SiO2) and reservoir drainage area were strong factors. Vegetation indices were more important than land cover types. The response of different metals to basin-scale factors varied greatly. The R.F. models performed well with prediction errors of 16.5% to 28.1%, showing that basin-scale parameters hold sufficient information for predicting potential metal concentrations. The results contribute to research and policymaking dependent on understanding large-scale factors of metal pollution.

Comparative analysis of groundwater quality statuses and associated health risk indices of metals and total hydrocarbons at locations of tank farm in Delta State, Nigeria

The study aimed at assessing the groundwater quality and the associated health implications of oil storage tank farms in Asaba, Oghara, Warri, and Koko towns, in Delta State, Nigeria. Fe, Cr, Cd, Ni, Pb, and V concentrations in the groundwater samples were determined using Atomic Absorption Spectrophotometry (AAS), while total hydrocarbons (THC) concentrations were determined using gas chromatography coupled with a flame ionization detector (GC-FID). The quality index of Warri groundwater was 66.38; being within the range of 51–75 was considered poor quality. The water quality indices (WQI) of Oghara, Koko, and Asaba were 163.79, 161.43, and 129.95 respectively, which were all > 100, hence amounting to very poor water quality status. Results indicated that children in Oghara who are orally exposed to chromium are at risk of cancer. Both adults and children orally exposed to THC in Oghara are also at risk of cancer. Furthermore, THC posed an oral route cancer risk to the children in Koko town. The study showed that chromium posed carcinogenic threats to children in Oghara, while THC posed carcinogenic threats to adults and children in Oghara and children alone in Koko. These risks are liable to be mediated through ingestion of the groundwater of Oghara and Koko by the susceptible groups.

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The WQI of Oghara, Koko, and Asaba were 163.79, 161.43, and 129.95 respectively, all > 100 (very poor water quality status).

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Chromium posed carcinogenic threats to children in Oghara, while THC posed carcinogenic threats to adults and children in Oghara and children alone in Koko.

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The risks are liable to be mediated through ingestion of the groundwater of Oghara and Koko.

Heavy metal profile of surface and ground water samples from the Niger Delta region of Nigeria: a systematic review and meta-analysis

This systematic review and meta-analysis estimated the pooled mean levels of heavy metals in ground and surface water samples obtained from the Niger Delta region of Nigeria (NDRN). PUBMED and Google Scholar databases were searched for studies published between 2000 and 2019, which assessed the levels of heavy metals in natural water samples obtained from the NDRN. Thirty one (31) studies which had a total of 951 water samples were identified. The pooled mean estimate (PME) from the meta-analysis indicates that the levels of Ni, Cd, Cr, and Pb in the majority of the natural water bodies from the NDRN are higher than the WHO safe permissible limit for drinking water. The contributions of prevailing anthropogenic activities to the observed heavy metal profiles of natural water sources from the NDRN were discussed. Stricter enforcement of safe environmental practices is necessary to protect the lives of the over 30 million inhabitants of this oil rich region.

Occurrence, spatial distribution and ecological risk assessment of trace elements in surface sediments of rivers and coastal areas of the East Coast of Bangladesh, North-East Bay of Bengal

Coastal and estuarine ecosystems provide habitats for many organisms. Recently, the estuaries and coastal areas of the East Coast of Bangladesh have become heavily contaminated due to dumping of untreated wastewater into the rivers from a number of different industries. The current study analyzes potentially toxic elements contamination in surface sediments of the Karnaphuli, Sangu, Bakkhali and Naf Rivers, Kutubdia and Moheshkhali Channel, and St. Martin's Island, and assesses the consequent ecological risks. The pollution load index (PLI), geoaccumulation index (I_geo) and potential ecological risk (PER) indices show that the contaminated sediments have negative effects on the aquatic environments. The PLI values ranged between 0.45 and 1.67, which suggests the severity of trace-element contamination. The mean I_geo values showed the sediments range from uncontaminated to heavily contaminated state. The Enrichment Factor (EF) values suggested that the sediments were contaminated by anthropogenic sources, and PER values demonstrate that sites at Sangu, Naf and St Martin's Island are less contaminated compared to sites at Karnaphuli, Bakkhali, Kutubdia and Moheshkhali. Overall, results showed that Karnaphuli river is the most contaminated and St Martin's Island is the least based on the spatial distribution of PLI, C_d, PER and ∑TUs of trace metals in surface sediments. Comparing with the neighboring countries, the concentrations of Cd and Pb were found to be higher while Cr is lower in the East Coast of Bangladesh than the estuarine and coastal waters of the Bay of Bengal rim countries. The present study reveals that the lack of water quality guidelines in Bangladesh for the coastal, estuarine and marine water escalated the dumping of untreated wastewater. Immediate measures need to be taken to address the ecological risks so that an effective management program can be undertaken. A systematic approach for collecting pollutant data and use of isotopes to trace anthropogenic sources of contamination is recommended for pollutants like toxic metals, pesticides and other contaminants in sediment and aquatic products in the entire coastal waters of the Bay of Bengal.

Assessing heavy metal contamination in soils using improved weighted index (IWI) and their associated human health risks in urban, wetland, and agricultural soils

Contamination of nine heavy metals (HMs) Zn, Pb, Cu, Cd, As, Co, Cr, Mo, and Ni in agricultural, urban, and wetland soils from Western and Rift Valley parts of Kenya was assessed using improved weighted index (IWI) and pollution loading index (PLI). Non-carcinogenic risks posed by the HMs were assessed using hazard quotients (HQ) and hazard index (HI), while carcinogenic risks were assessed using cancer risks (CR) and total cancer risks (TCR). The average concentration of Zn, Cr, Ni, Pb, Co, Cu, As, Mo, and Cd was 94.7 mg/kg, 43.6 mg/kg, 22.3 mg/kg, 21.0 mg/kg, 19.8 mg/kg, 18.0 mg/kg, 16.3 mg/kg, 1.83 mg/kg, and 1.16 mg/kg, respectively. IWI ranged from 0.57 to 6.04 and categorized 6.82% of the study sites as not polluted, 27.3% as slightly polluted, 43.2% as moderately polluted, and 22.7% as seriously polluted. PLI ranged from 0.38 to 3.95 and classified 15.9% of the sites as not polluted, 61.4% as slightly polluted, 20.5% as moderately polluted, and only 2.3% as seriously polluted. Wetlands retained more HMs from both urban and agricultural runoff and were therefore the most polluted. The heavy metals did not pose any risks via inhalation and dermal contact, but HQingestion for As for children was >1 in 2.3% of the sites studied. CR via ingestion and TCR for As were above the allowable limits for children and adults indicating high risks of cancer. Intensive agriculture and urbanization should be closely monitored to prevent further HM pollution.

Blood lead level and nutritional status indicators in preadolescent Polish schoolchildren

BACKGROUND

Environmental pollutions with heavy metals may have toxic effects on human health and development. One of the most detrimental is lead exposure, which may disturb neurodevelopment and linear growth in children. However, data on the effect of lead exposure on nutritional and weight status in children are limited, thus this study aimed to assess the effect of blood lead (Pb) level on nutritional and weight status in preadolescent schoolchildren from the industrialized, mining region in southwestern Poland.

METHODS

Our study sample involved N = 709 schoolchildren (402 boys and 307 girls) in the preadolescent developmental period (7-11 years of age for boys and 7-10 years of age for girls). Anthropometric measurements were used to assess nutritional and weight status: body mass index (BMI), mid-upper arm circumference (MUAC) and skinfolds thicknesses (triceps, subscapular, abdominal and the sum of skinfolds). Blood Pb level was evaluated and divided into two groups: above (>3.7 μg/dL) and below median value (≤3.7 μg/dL).

RESULTS

Analysis of covariance (with children's age controlled as a covariate) revealed that children with blood Pb level above median value had significantly lower values of BMI, MUAC and all skinfolds (at least p < 0.01). However, this effect was significant only in boys, whereas in girls differences were non-significant (p > 0.05). The highest effect size of blood Pb level was noted for skinfolds thicknesses (partial η²: 0.015 for the sum of skinfolds).

CONCLUSIONS

Nutritional status in children with higher blood Pb level is significantly impaired in preadolescent boys, who appear to be more sensitive to this environmental factor. Our findings indicate a particular need for nutritional and environmental interventions among preadolescent children in regions with higher lead exposure.

Assessment of Potential Ecological Risk of Heavy Metals in Surface Soils of Laizhou, Eastern China

With the rapid industrialization and urbanization, more attention is turning to heavy metal contamination in the soil environment. To assess the potential environmental risk on soil, a comprehensive geochemistry study on heavy metal was performed in Laizhou, eastern China, using 3834 surface soil samples (0–20 cm, regular grid of 1 × 1 km2) and 60 layered soil samples (0–200 cm) were analyzed. The average concentrations of As, Cd, Cr, Cu, Hg, Ni, Zn and Pb were 7.60 mg·kg−1, 0.15 mg·kg−1, 45.50 mg·kg−1, 19.10 mg·kg−1, 44.00μg·kg−1, 18.70 mg·kg−1, 51.40 mg·kg−1 and 29.00 mg·kg−1, which were lower than the threshold levels of the Grade II criteria of China national environment quality standard for soil, but the contents of As, Cd, Hg, and Pb were higher than background values of eastern Shandong Province surface soil. Fractionation analysis showed that the potential bioavailability in surface soils decreases in the order of Cd > As > Cu > Ni > Zn > Cr > Pb > Hg. Soil assessments with enrichment factor, contamination factor, Nemerow composite index, geo-accumulation index and potential ecological risk index, indicate the soil in Laizhou is contaminated strongly with As, Cd and Hg and a moderately Cr, Ni, Cu and Zn. The level of Pb pollution is between moderate to high. Multivariate analyses suggest that Cr and Ni were derived mainly from natural sources, and As, Cd, Pb, while Hg mostly came from anthropogenic sources. Cu and Zn were from a mixture of anthropogenic and natural sources. Our results demonstrate that more attention should be paid to monitoring soil quality in the heavily polluted site.

Potential toxic metals (PTMs) contamination in agricultural soils and foodstuffs with associated source identification and model uncertainty

The research aimed to find out physiochemical properties, metal concentration, sources of metals using statistical analyses, and positive matrix factorization (PMF) model using 315 soil and 250 foodstuff samples (25 species) in Jhenidah as well as Kushtia district, Bangladesh. The range of Pb, Cd, As, Cu, Ni and Cr contents (mg/kg) in soils were found to be 0.97-114.72, 0.11-7.51, 1.07-23.38, 0.89-122.91, 0.91-77.32 and 0.7-23.03 mg/kg, respectively, whereas those in foodstuff samples were found to be 0.46-11.48, 0.30-11.54, 0.47-9.21, 0.20-3.59, 0.001-1.76, and 0.27-5.93 mg/kg, respectively. PMF model revealed that Cu (81.4%) in the study area soils were predominantly contributed by vehicular fuel combustion, Cr (84.9%) was primarily of natural origin, Pb (73%) resulted from traffic emissions, Cd (74.3%), and As (63.4%) mainly came from agricultural practices while Ni (70.9%) was dominated as industrial pollution. EF > 1.5 of Cu, As, and Pb suggesting mild contamination; however, soils from all the studied sites revealed moderate potential ecological risk. Cr recorded BCF values of >1 in the majority of the examined crops, suggesting higher uptake of Cr than other metals. Cr, Ni, As, and Pb showed cancer risks from food intake and risk values were greater than the threshold range (10^-4), suggesting potential cancer risks.

Environmental implications of petroleum spillages in the Niger Delta region of Nigeria: A review

The issue of environmental pollution has been recognized as a typical example of an anthropogenic activity that constitutes a global challenge coupled with the influence of climate change. This has constituted several hazards which include bioaccumulation of toxic substances, pollution of the aquatic environment, and high rate of dilapidation of soil structure and texture, health hazards, high level of imbalance in the ecosystem and a high level of toxicity in humans and the environment. Despite the intervention of governments, industries, researchers and relevant stakeholders, these problems remain paramount in most regions. Therefore, given the aforementioned, it is essential to identify sustainable remediation techniques, innovative knowledge on remediation strategies and clean up techniques that could help in the mitigation of all these highlighted challenges. Moreover, several studies have revealed the deleterious influence of petroleum or oil spillages resulting in irreparable environmental dilapidation and other potential hazards to human health, agriculture, climate system, and the ecosystem in general. From the systematic analysis of the evidence-based, meta-data-based review and other reviewed literature, it is noticeable that there is scant holistic review study that will incorporate all these aforementioned environmental implications resulting from the activities of petroleum resources in the Niger Delta region of Nigeria (NDRN) in just a single study. In the interim, it is alleged that there is hardly a permanent and tangible solution to these petroleum spillage issues and their impacts on the region; albeit, awareness will be fundamental for its mitigation. Hence, this review study will attempt to fill this gap by holistically reviewing the selected environmental implications of petroleum spillages in the NDRN drawn from 219 evidence and meta-data-based reviews and other articles. Furthermore, the relevant legal frameworks that could guild in protecting against environmental issues and petroleum spillages, are discussed in this study. In conclusion, the study cautiously provides a way forward by submitting that effective research and development measures ranging from public health assessments of petroleum contamination to an all-embracing application of bioremediation technology should frequently be carried out as a matter of urgency with resilient adaptation, mollification and management of these menaces.

Effects of combined treatment of cadmium and oxytetracycline on the terrestrial isopod Porcellio leavis

The influence of pharmaceutical residues and heavy metals on living organisms has received global attention. The present study assessed the interactive effect of antibiotic residues and heavy metals in soil, as contaminated food with cadmium (Cd) and oxytetracycline (OTC) on the isopod Porcellio leavis. It was fed on fresh plant leaves contaminated with different concentrations of cadmium, Cd+OTC1000 ppm, Cd+OTC2000 ppm and Cd+OTC3000 ppm for 4 weeks. The changes in the feeding patterns, protein, lipid peroxidation (LPO), catalase activity (CAT), and total free amino acids (TFAA) were recorded. There were significant differences in the obtained results where Cd reduced the egestion ratio (ER) however, OTC enhanced this ratio. Biochemical analysis illustrated that combination between OTC and Cd inhibits the toxic effects of Cd at low concentration (1000 ppm), while at high concentration (3000 ppm) raise the toxicity. Detailed studies are required for further understanding of the interaction between OTC and heavy metals, and also its impact on soil animals and for improving soil risk evaluation.

Review on the Evaluation of the Impacts of Wastewater Disposal in Hydraulic Fracturing Industry in the United States

This paper scrutinized hydraulic fracturing applications mainly in the United States with regard to both groundwater and surface water contamination with the purpose of bringing forth objective analysis of research findings. Results from previous studies are often unconvincing due to the incomplete database of chemical additives; after and before well-founded water samples to define the change in parameters; and specific sources of water pollution in a particular region. Nonetheless, there is a superior chance of both surface and groundwater contamination induced by improper and less monitored wastewater disposal and management practices. This report has documented systematic evidence for total dissolved solids, salinity, and methane contamination regarding drinking water correlated with hydraulic fracturing. Methane concentrations were found on an average rate of 19.2 mg/L, which is 17 times higher than the acceptance rate and the maximum value was recorded as 64.2 mg/L near the active hydraulic fracturing drilling and extraction zones than that of the nonactive sites (1.1 mg/L). The concentration of total dissolved solids (350 g/L) was characterized as a voluminous amount of saline wastewater, which was quite unexpectedly high. The paper concludes with plausible solutions that should be implemented to avoid further contamination.

Ecological security and health risk assessment of soil heavy metals on a village-level scale, based on different land use types

Land use affects the accumulation of heavy metals in soil, which will endanger ecological safety and human health. Taking the village as an administrative unit, the ecological safety and health risks of heavy metals, namely, Cr, Cu, Zn, and Pb in soils in the Houzhai River Watershed of Guizhou Province, China, were evaluated based on land use types by the Hakanson potential ecological risk methods and human health risk model. Results showed that the spatial heterogeneity of Cu and Zn was greatly affected by primary structural factors, and Cr and Pb were interfered by both structural factors and human activities. The geo-accumulation index of the heavy metals showed a light pollution in the study area. The comprehensive potential ecological risk of heavy metal in the area was divided into three levels: slight, moderate, and intense, and it is spatially high in the northwest and low in the southeast. Both non-carcinogenic risk and carcinogenic risk of the heavy metals to the human body are not significant and are acceptable. The risks of children are higher than adults, and direct intake is the primary route of exposure in the area. The potential ecological risk and human health risk of soil heavy metals are relatively obviously affected by digital elevation data and normalized vegetation index. The study has certain reference value for the prevention and control of regional soil heavy metal risk.

Comprehensive Evaluation of the Control Efficiency of Heavy-Metal Emissions during Two-Step Thermal Treatment of Sewage Sludge

Recycling the phosphorus in sludge by incineration has received great interest at home and abroad. However, heavy metals (HMs) is a restrictive factor for SS thermal treatment. In this study, a comprehensive evaluation method was adopted to evaluate the comprehensive control efficiency of HM emissions during two-step thermal treatment (incineration-calcination). The effects of temperature, calcination time, and additives (CaO and NaCl) on leaching rates, stabilized rates, and comprehensive control efficiency of HM emissions were investigated. Results showed that comprehensive control efficiency increased significantly with an increase of temperature because of the transformation of chemical speciation from a leachable to a more stable combined form. Additives Cao and NaCl promoted the volatilization of HMs and reduced the comprehensive control efficiency. The highest comprehensive control efficiency of HM emissions was 78% when the incineration temperature reached 950 °C. Furthermore, a comparison was made between leaching rates, stabilized rates, and a comprehensive evaluation method. The results were inconsistent when leaching rates and stabilized rates were adopted. In contrast, when the comprehensive evaluation method was used, the results were coordinated and unique. This work can provide a promising approach for the evaluation of control efficiency of HM emissions during the process of thermal treatment of sludge.

Spatial distribution and assessment of the human health risks of heavy metals in a retired petrochemical industrial area, south China

Petrochemical industries are widely distributed in China. As a negative consequence, heavy metals in petrochemical area can result in soil contamination. However, the relevant research of heavy metals contamination in petrochemical area was few. In this study, a total of 103 topsoil samples (<20 cm) and 25 profile soil samples were collected and examined in a retired petrochemical industrial area, South China. The results showed the mean contents of Hg, Cd, As, Pb, Ni and Cu were 0.18, 0.69, 16.22, 47.24, 31.62 and 93.06 mg kg^-1, respectively. The spatial distribution of six metals in topsoil was largely attributed to the industrial activities during the petroleum refining and transshipment process. Ni was the main pollutant in the petroleum refining process. While, the contamination of other metals mainly were caused by the leakage of the oil during transshipment. The migration of six metals to subsoil layers was also observable. In accordance, Hg, Cd, As, Pb, Cu, and Ni dropped by 95.02, 71.91, 89.45, 90.88, 99.22, and 65.07%, respectively, compared to their contents in topsoil. The contamination of the heavy metals was mainly caused during the process of petroleum refining and transshipment. The distribution of heavy metals in the factory was mainly affected by the industrial activities or the lateral infiltration of Lianhuashan River. Soil ingestion was the primary pathway for children and adults exposure to heavy metals. The total non-cancer human health risk induced by heavy metals was within the limit of USEPA (10^-6 a^-1). While the cancer risks alone induced by As through soil ingestion to children was 1.14 × 10^-6 a^-1, which exceeded the limit of USEPA. This study indicated that not only petroleum hydrocarbon but also heavy metals can cause soil contamination in a retired petrochemical industrial area, which provides a novel cognition. Altogether, measures should be taken in practice to substantially improve the soil quality in petrochemical industrial area.

Contamination Level, Ecological Risk, and Source Identification of Heavy Metals in the Hyporheic Zone of the Weihe River, China

The sediment pollution caused by different metals has attracted a great deal of attention because of the toxicity, persistence, and bio-accumulation. This study focuses on heavy metals in the hyporheic sediment of the Weihe River, China. Contamination levels of metals were examined by using "geo-accumulation index, enrichment factor, and contamination factor" while ecological risk of metals were determined by "potential ecological risk and risk index." The pollutant accumulation of metals ranked as follows: "manganese (Mn) > chromium (Cr) > zinc (Zn) >copper (Cu) > nickel (Ni) > arsenic (As) > lead (Pb)". The geo-accumulation index identified arsenic as class 1 (uncontaminated to moderate contamination), whereas Cu, Cr, Ni, Zn, Pb, and Mn were classified as class 0 (uncontaminated). According to the enrichment factor, arsenic originated through anthropogenic activities and Cr, Ni, Cu, Zn, and Pb were mainly controlled by natural sources. The contamination factor elucidated that sediments were moderately polluted by (As, Cr, Cu, Zn, Mn, and Pb), whereas Ni slightly contaminated the sediments of the Weihe River. All metals posed a low ecological risk in the study area. The risk index revealed that contribution of arsenic (53.43 %) was higher than half of the total risk.

Daily exposure to toxic metals through urban road dust from industrial, commercial, heavy traffic, and residential areas in Petaling Jaya, Malaysia: a health risk assessment

Human health is threatened by significant emissions of heavy metals into the urban environment due to various activities. Various studies describing health risk analyses on soil and dust have been conducted previously. However, there are limited studies that have been carried out regarding the potential health risk assessment of heavy metals in urban road dust of < 63-μm diameter, via incidental ingestion, dermal contact, and inhalation exposure routes by children and adults in developing countries. Therefore, this study evaluated the health risks of heavy metal exposure via ingestion, dermal contact, and inhalation of urban dust particles in Petaling Jaya, Malaysia. Heavy metals such as lead (Pb), chromium (Cr), zinc (Zn), copper (Cu), and manganese (Mn) were measured using dust samples obtained from industrial, high-traffic, commercial, and residential areas by using inductively coupled plasma mass spectrometry (ICP-MS). The principal component and hierarchical cluster analysis showed the dominance of these metal concentrations at sites associated with anthropogenic activities. This was suggestive of industrial, traffic emissions, atmospheric depositions, and wind as the significant contributors towards urban dust contamination in the study sites. Further exploratory analysis underlined Cr, Pb, Cu, and Zn as the most representative metals in the dust samples. In accommodating the uncertainties associated with health risk calculations and simulating the reasonable maximum exposure of these metals, the related health risks were estimated at the 75th and 95th percentiles. Furthermore, assessing the exposure to carcinogenic and non-carcinogenic metals in the dust revealed that ingestion was the primary route of consumption. Children who ingested dust particles in Petaling Jaya could be more vulnerable to carcinogenic and non-carcinogenic risks, but the exposure for both children and adults showed no potential health effects. Therefore, this study serves as an important premise for a review and reformation of the existing environmental quality standards for human health safety.

Estimating the pollution characteristics and health risks of potentially toxic metal(loid)s in urban-industrial soils in the Indus basin, Pakistan

The Indus Basin Irrigation Network (IBIN) plays a vital role in the agricultural system of Pakistan, irrigating seventeen million hectares of cultivated areas. Rapid urbanization, industrialization, and agricultural activities along the Indus basin have influenced the soil quality and human health; it is, therefore, critical to know its pollution characteristics. Soil samples from Indus basin, i.e., Abbottabad (ABT), Haripur (HRP), Attock (ATC), and Islamabad (ISB) have been analyzed for the total contents of potentially toxic metal(loid)s (PTMs) in the top layer. The topsoil samples from 0 to 10 cm depth have been further investigated using different pollution indices and human health risk assessment models. The contamination degree of soil pollution was highest in ISB (33.75), followed by ABT (25.30) and ATC (23.57). The assessment of the daily intake of PTMs by children and adults through different pathways revealed ingestion as the significant exposure pathway. Cr was found to be the major element posing non-carcinogenic health risks to children at ATC whereas the non-carcinogenic risks posed by all other PTMs were within the safe limit. Furthermore, life-time carcinogenic risks for Ni followed by Cr and Cd were greatly exceeded at all locations and As at ATC and ISB for both age groups, but comparatively children were found to be at a higher risk of carcinogenicity. Hence, efficient remediation strategies are needed to reduce the increasing content and health risks of PTMs in the Indus basin.

Potential Ecological Risk and Health Risk Assessment of Heavy Metals and Metalloid in Soil around Xunyang Mining Areas

Xunyang is rich in various metal minerals and is one of the four major metal mining areas in Shaanxi province, China. To explore the effects of soil heavy metals and metalloid pollution on the environment and human health around the mining areas, four places—Donghecun (D), Gongguan (G), Qingtonggou (Q) and Nanshagou (N)—were selected as the sampling sites. Potential ecological risk (PER) and health risk assessment (HRA) models were used to analyze the environmental and health risks around the mining areas. The concentration of heavy metals (Cd, Cr, Pb, Zn, Ni, Cu, Hg) and metalloid (As) in cultivated land in the vicinity of Xunyang mining areas indicated that, except for Cu, the remaining elements detected exceeded the threshold values at some sites. The geo-accumulation index (IGeo) revealed that soils in G and Q could be identified as being extremely contaminated. PER indicated that there was significantly high risk at G and Q for Hg. In N, Pb recorded the highest E r i , which also demonstrates a considerable pre-existing risk. HRA indicated that the hazard index (HI) for both carcinogenic and non-carcinogenic risks was much higher among children than among adults, and the ingestion pathway contributed the greatest risk to human health, followed by the dermal pathway and inhalation. Because the HI values of the metals and metalloid in the study areas were all lower than 1, there was no significant non-carcinogenic risk. However, the carcinogenic risk for Cr is relatively higher, surpassing the tolerable values in G, Q, and N. This study analyzed the ecological risks and human health risks of heavy metals and metalloid in farmland soils near the sampling mining areas, and demonstrated the importance of environmental changes caused by land development in the mining industry.

Copper environmental toxicology, recent advances, and future outlook: a review

Copper (Cu) is one of the micronutrients needed by living organisms. In plants, Cu plays key roles in chlorophyll formation, photosynthesis, respiratory electron transport chains, oxidative stress protection as well as protein, carbohydrate, and cell wall metabolism. Therefore, deficiency of Cu can alter various functions of plant metabolism. However, Cu-based agrochemicals have traditionally been used in agriculture and being excessively released into the environment by anthropogenic activities. Continuous and extensive release of Cu is an imperative issue with various documented cases of phytotoxicity by the overproduction of reactive oxygen species (ROS) and damage to carbohydrates, lipids, proteins, and DNA. The mobility of Cu from soil to plant tissues has several concerns including its adverse effects on humans. In this review, we have described about importance and occurrence of Cu in environment, Cu homeostasis and toxicity in plants as well as remediation and progress in research so far done worldwide in the light of previous findings. Furthermore, present review provides a comprehensive ecological risk assessment on Cu in soils and thus provides insights for agricultural soil management and protection.

Assessment of the human health risks of heavy metals in nine typical areas

Human health risks of five different heavy metals were assessed in nine typical areas in Asia, Europe, and Africa. The geoaccumulation index (I_geo) of arsenic (As) in Hyderabad (HB), cadmium (Cd) in Veles (VL), and lead (Pb) in Murcia (MC) were found to be 5, indicating extreme contamination. This is related to their high concentrations in soil. The concentration of As in wheat in Niger Delta (ND) and European Union (EU) areas were 3.3 and 2.55 mg/kg, which were 22 and 17 times respectively of the World Health Organization (WHO)/Food and Agriculture Organization (FAO) criteria. In general, the concentrations of heavy metals in wheats were higher than those in corns, indicating that heavy metals were easier to accumulate in wheats than in corns. The human risks induced by the carcinogenic metals As and Cd were much higher than those induced by noncarcinogenic metals in different exposure ways. The human health risks of heavy metals in different exposure ways were R_w-ing > R_c-ing > R_s-ing > R_s-der > R_s-inh. The human health risks induced by wheat ingestion for adults and children accounted for 67.75-97.52% and 69.52-98.04%, respectively, of the total human health risks. The total human health risks in the VL and MC areas were 1.58 × 10^-4 a^-1 and 1.3 × 10^-4 a^-1 for adults and 1.14 × 10^-4 a^-1 and 9.47 × 10^-5 a^-1 for children, respectively, which were significantly high according to the Environmental Protection Agency and International Commission on Radiological Protection. The ranking of the total human health risks in different areas were R_VL > R_MC > R_ND > R_EU > R_HB > R_KY > R_TB > R_MLV > R_NHM. The total human health risks of adults were higher than those of children.

Effect of oil spills on infant mortality in Nigeria

Onshore oil spills can lead to irreversible environmental degradation and potentially pose hazards to human health, but scientific evidence on their health effects is lacking. We fill this gap by studying the causal effects of onshore oil spills on neonatal and infant mortality rates. We compare siblings conceived before and after nearby oil spills and find that nearby oil spills double the neonatal mortality rate. Given that oil spills occur with high frequency in the densely populated areas along pipelines in Nigeria, they are the cause of an alarming ongoing human tragedy. Our results suggest that efforts to prevent oil spills in the Niger Delta could save the lives of thousands of newborns every year.

Oil spills can lead to irreversible environmental degradation and are a potential hazard to human health. We study how onshore oil spills affect neonatal and infant mortality by combining spatial data from the Nigerian Oil Spill Monitor with Demographic and Health Surveys. To identify a causal effect, we compare siblings born to the same mother, conceived before and after a nearby oil spill. We find that nearby oil spills that occur before conception increase neonatal mortality by 38.3 deaths per 1,000 live births, which corresponds to an increase of around 100% on the sample mean. The effect is fairly uniform across girls and boys, socio-economic backgrounds, and locations. We show that this effect is not driven by events related to oil production or violent conflict. Rather, our results are consistent with medical and epidemiological evidence showing that exposure to hydrocarbons can pose risks to fetal development. We provide further evidence suggesting that the effects of oil spills on neonatal mortality persist for several years after the occurrence of an oil spill.

Ecotoxicity evaluation and human risk assessment of an agricultural polluted soil

The present study aims to evaluate the nature and level of chemical pollution as well as the potential toxicity and ecotoxicity of an agricultural soil irrigated by the water of Litani River. Our findings showed that the soil was mainly contaminated by alkanes (hentriacontane, octadecane, hexadecane) and metal trace elements (nickel, vanadium, chromium, and manganese). Soil organic extracts showed high cytotoxicity against human hepatic (HepG2) and bronchial epithelial cells (Beas-2B). Soil ecotoxicity was revealed by seed germination inhibition of several plant species (wheat, clover, alfalfa, tall fescue, and ryegrass) ranging from 7 to 30% on the polluted soil compared to non-polluted one. In addition, significant decreases in telluric microbial biomasses (bacterial and fungal biomasses), quantified by phospholipid fatty acids (PLFA) analysis were observed in polluted soil compared to non-contaminated soils. The density of the arbuscular mycorrhizal fungal (AMF) spores isolated from the polluted soil was about 316 spores/100 g. Three main AMF species were identified as Funelliformis mosseae, Septoglomus constrictum, and Claroideoglomus lamellosum. Moreover, 16 indigenous plant species were inventoried with Silybum marianum L. as the dominant one. Plant biodiversity indices (Shannon, Simpson, Menhinick, and Margaleff) were lower than those found in other contaminated soils. Finally, it was found that all the present plant species on this polluted site were mycorrhized, suggesting a possible protection of these plants against encountered pollutants, and the possibility to use AMF-assisted phytoremediation to clean-up such a site.

Understanding the Association between Environmental Factors and Longevity in Hechi, China: A Drinking Water and Soil Quality Perspective

The aging population is a big challenge all over the world. However, there are few studies to date investigating the effects of trace element and mineral levels in drinking water and soil (especially in karst areas) on longevity. This study aims to examine temporal and spatial variations in longevity in Hechi (which is recognized as a longevity city) and to investigate relationships between longevity and trace element and mineral levels in drinking water and soils in this city (the karst landscape). Population data were collected from relevant literature and four national population censuses in 1982, 1990, 2000 and 2010. Drinking water and soil samples from Hechi were collected and analyzed. The results demonstrated an obvious clustered distribution for the longevity population in Hechi that has existed stably for decades. The longevity index tended to be significantly positively correlated with H₂SiO₃, Ca and Fe in drinking water and significantly negatively correlated with Sr in soil, indicating that drinking water characteristics contributed significantly to the observed regional longevity. The karst landscape is responsible for abundant trace elements in underground rivers in Hechi, which are beneficial to human health when consumed as drinking water. Good quality and slightly alkaline drinking water rich in trace elements such as H₂SiO₃, Ca, Fe, Na, Mg and low in heavy metals such as Pb and Cd might be an important factor contributing to the longevity phenomenon in Hechi.

Potentially toxic elements in soil of the Khyber Pakhtunkhwa province and Tribal areas, Pakistan: evaluation for human and ecological risk assessment

Potentially toxic elements (PTEs) contaminations in the soil ecosystem are considered as extremely hazardous due to toxicity, persistence and bioaccumulative nature. Therefore, this study was aimed to summarize the results of published PTEs in soil of Khyber Pakhtunkhwa and Tribal areas, Pakistan. Results were evaluated for the pollution quantification factors, including contamination factor (CF), pollution load index (PLI), ecological risk index (ERI) and human health risk assessment. The highest CF (797) and PLI (7.35) values were observed for Fe and ERI (857) values for Cd. Soil PTEs concentrations were used to calculate the human exposure for the risk assessment, including chronic or non-carcinogenic risks such as the hazard quotient (HQ) and carcinogenic or cancer risk (CR). The values of HQ were > 1 for the Cd, Co and Cr in Khyber Pakhtunkhwa and Tribal areas. Tribal areas showed higher values of ERI, HQ, and CR as compared to the Khyber Pakhtunkhwa that were attributed to the mining activities, weathering and erosion of mafic and ultramafic bedrocks hosting ophiolites. This study strongly recommends that best control measures need to be taken for soil PTEs with the intent to alleviate any continuing potential threat to the human health, property and environment, which otherwise could enter ecosystem and ultimately the living beings. Further studies are recommended to combat the soil PTEs concentrations and toxicity in the Tribal areas for a best picture of understanding the element effects on human, and environment can be achieved that will lead to a sustainable ecological harmony.

Predicted Mercury Soil Concentrations from a Kriging Approach for Improved Human Health Risk Assessment

Health-risks from contaminated soils are assessed all over the world. An aspect that many risk assessments share is the heterogeneity in the distribution of contaminants. In a preceding study, we assessed potential health-risks for mothers and children living on mercury-contaminated soils in Switzerland using human biomonitoring-values (HBM) and soil samples. We assessed 64 mothers and 107 children who had resided in a defined area for at least 3 months. HBM-concentrations for mercury in urine and hair were measured, a detailed questionnaire was administered for each individual, and more than 4000 individual mercury soil values were obtained in 2015. In this study, we aimed at investigating possible associations of mercury soil- and HBM-values by re-analyzing our data, using predictions of the mercury concentrations at the exact location of the participant’s homes with a kriging approach. Although kriging proved to be a useful method to predict mercury soil concentrations, we did not detect an association between mercury soil- and HBM-values, in agreement with earlier findings. Benefits of geostatistical methods seem to be limited in the context of our study. Conclusions made in our preceding study about potential health risks for the residential population are robust and not altered by the current study.

Ecological and human health risks arising from exposure to metals in urban soils under different land use in Nigeria

The concentrations of eight metals (Cd, Pb, Cr, Ni, Cu, Mn, Zn and Fe) were measured in soils under different land use in an urban environment of the Niger Delta in Nigeria. The aim was to provide information on the potential ecological and human health risks associated with human exposure to metals in these soils. The potential ecological risk due to metals in soils of these land use types falls in the range of low to moderate ecological risk with a significant contribution from Cd. The severity of the individual metals to ecological risk in these land use types followed the order Cd > Pb > Zn > Cu > Ni > Cr > Mn. The non-carcinogenic risk, expressed in terms of the hazard index (HI), arising through exposure to metals through oral, dermal and inhalation pathways, was greater than 1 for children in the majority of the land use types and less than 1 for adults for all land use types. This indicated that there are considerable non-cancer risks arising from childhood exposure to metals in soils of these land use types. The cancer risk values were within acceptable threshold values indicating a negligible cancer risk for both children and adults exposed to metals in these urban soils.

The reach of human health risks associated with metals/metalloids in water and vegetables along a contaminated river catchment: South Africa and Mozambique

BACKGROUND

Anthropogenic pollution was identified as an environmental problem of concern when, in 2008, dozens of crocodiles died in the Olifants River catchment near the border of South Africa and Mozambique. Given the close proximity of households to the river and their making use of river water, we aimed to determine to what extent water pollution has an impact on health of indigent communities in South Africa and Mozambique in the catchment area.

METHODS

Water and vegetable samples were collected from the study areas. Biota samples were washed with double de-ionized Milli-Q water and freeze-dried. Heavy metal analyses in water and vegetables were done by means of Inductively Coupled Plasma Optical Emission Spectroscopy. Metal concentrations were applied in a human health risk assessment to estimate health risks.

RESULTS

Mean concentrations of antimony, arsenic, cadmium, chromium, mercury, molybdenum, nickel and selenium in water samples from South Africa exceeded the World Health Organization guidelines for safe levels of intake. Only iron exceeded the recommended guidelines in water samples from Mozambique. Metals/metalloids were found in lower concentrations at Mozambique sites downstream of South African sites. In vegetables, uranium was between 10 and 20 times above safe guidelines in South Africa and between 3 and 6 times in Mozambique. Arsenic in water samples posed the highest cancer risk.

CONCLUSIONS

Even with a reduction in the metal concentrations in river water from South Africa to Mozambique, the potential to cause adverse human health impacts from direct use of polluted river water is evident in both countries.

Toxic effects of oxytetracycline and copper, separately or combined, on soil microbial biomasses

The production of commercial livestock and poultry often involves using with antibiotics and feed additives, such as oxytetracycline (OTC) and copper (Cu). These are often excreted into the soil by animal feces; hence, combined pollutants may contaminate the soil. To evaluate single and combined toxic effects of OTC and Cu on the soil ecology, changes in quantities of bacteria, fungi, and actinomycetes in the soil were studied over a 28-d incubation period by a plate count method, microbes numbers counted on days 7, 14, 21, and 28. Abundances of ammonia monooxygenase (amoA) gene expression by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in soil samples also were tested by real-time polymerase chain reactions (RT-PCRs) on day 21. The results revealed that the numbers of bacteria, fungi and actinomycetes and amoA genes copies of AOA and AOB were reduced seriously by exposure to Cu (1.60 mmol/kg). Similarly, the combined pollution treatments (mole ratios of OTC: Cu was 1:2, 1:8, and 1:32) also had inhibitory effect on bacteria, fungi, and actinomycetes numbers and amoA gene copies of AOA and AOB; the inhibitory rate was on obvious growth trend with the increasing mole ratios. Effects from single OTC pollution were found on bacteria (days 7 and 14), fungi (days 7, 14, 21, and 28), and AOA-amoA gene copies (day 21), with promotion at a low concentration (0.05 mmol/kg) and suppression at higher concentrations (0.2 and 0.8 mmol/kg). Also, numbers of bacteria, fungi, and actinomycetes decreased with longer culture times. Combining OTC and Cu led to a higher inhibition of soil microbes than when either chemical was used alone. However, there was no significant relationship between single and combined toxic chemicals because of their complicated interactions, either antagonistic or synergistic. The results also indicated the sensitivity of bacteria, fungi, actinomycetes on toxic chemicals existed difference and that the AOA were more tolerant than the AOB to these chemicals.

Study of factors involved in the gravimetric separation process to treat soil contaminated by municipal solid waste

The current research investigated the effectiveness of a gravimetric process (shaking table) to treat soil contaminated by municipal solid waste. A detailed characterization of the inorganic pollutants was performed, followed by concentrating the metals within smaller volumes using the shaking table technology. The densimetric examination of the 1-2 mm and 0.250-1 mm fractions of the contaminated soil showed that lead (Pb), copper (Cu), and tin (Sn) were mostly concentrated in the heavy fraction (metal removals > 50%). Scanning electron microscopy coupled with elemental analysis indicated the relevance of using gravimetric processes to treat this soil sample. The influence of shaking table parameters was determined using a Box-Behnken design. The tilt and washing water flow demonstrated significant effects on the motion of the 1-2 mm soil fraction and on the removal of Pb, Cu, and Sn. The results obtained under the optimal settings of the shaking table defined using the Box-Behnken methodology when treating the 1-2 mm fraction were close to those obtained when using dense media separation. The recovered mass of the concentrate was approximately 20.8% (w.w^-1) of the total mass. The removals of Pb, Cu, and Sn were estimated to be 67.3%, 54.5% and 54.6% respectively. The predicted and experimental mass distributions of the medium (1-2 mm) and fine-sized (0.250-1 mm) particles were compared successively under some selected conditions. The mass distribution of both fractions showed similar tendencies in response to the forces applied by each condition. However, lowering the forces induced by the bumping action and the flowing film was recommended so as to efficiently treat the fine fraction (0.250-1 mm). The recovered mass of the concentrate (10%) was slightly lower than that obtained by dense media separation (13%). However, satisfactory removal yields were obtained for Pb, Cu, and Sn (42.7%, 23.6%, and 35% respectively).

Index analysis and human health risk model application for evaluating ambient air-heavy metal contamination in Chemical Valley Sarnia

The impacts of air emissions as a consequence of industrial activities around communities of human habitation have been extensively reported. This study is the first to assess potential adverse human health effects in the Chemical Valley Sarnia (CVS) area, around the St. Clair River, using health risk models, ecological and pollution indices. Large quantities of particulate matters (PM) are generated from anthropogenic activities, which contain several heavy metals in trace quantities with potentially adverse effects to humans and environmental health. The distribution, and human health impact assessment of trace element concentrations in PM fractions were examined. Elemental concentrations of As, Cd, Cr (VI), Cu, Fe, Mn, Pb, Ni, Zn were determined in the PM size-segregated samples collected from the CVS area between 2014 and 2017. The results showed relatively high concentration of PM_<2.5 (87.19±8.1(mgm³)) which is approximately 4 times the WHO air quality guidelines. Pb concentration (143.03 ± 46.87ηg/m³) was 3.6 times higher than the air quality standards of NAAQS. Cr (VI) showed moderate to considerable contamination ( C_f=4) in the CVS while Cr (VI), Pb, and Ni had enrichment factor E_f < 3 (minimal), signifying contributions from anthropogenic activities. Pollution load index (P_Li) value observed was 1.4 indicating human health risk from the PM, especially for the children in the area. The deposition fluxes (DΦ) showed that PM-bound metals could potentially bypass the head airways and cause damages to the tracheobronchial tree, increasing the human health risks of nephroblastomasis development. The main route of entry for the heavy metal bound PM in humans were observed as through ingestion and inhalation. The highest total excess cancer risks observed for children (6.7×10^-4) and adult (1.0×10^-4) indicating potential cancer effects. The Incremental Lifetime Cancer Risk (ILCR) increased from Pb < Ni < Cd < Cr (VI) < As. Overall, children are more likely to develop carcinogenic and non-carcinogenic health effects from exposures to elemental concentrations of airborne PM in the study area.