Pollution, human health risk assessment and spatial distribution of toxic metals in urban soil of Yazd City, Iran

Human health and ecological risk assessment of heavy metals in topsoil of different peatland use types

Peatlands, known for their ability to retain and immobilize heavy metals due to unique waterlogged conditions and organic matter, face challenges when subjected to disturbances such as land use changes. These disruptions alter the organic matter, redox potential, and pH of the peatsoil, potentially influencing the migration, mobilization, and increased availability of stored heavy metals. Peatsoil samples from various peatland use types (improved and semi-natural grassland, forest, industrial cutaway bog) were collected to assess the human health and ecological risk associated with heavy metals (Cd, Cu, Hg, Pb, and Zn) in Co-Offaly, Ireland. Results reveal variations in heavy metal concentrations across peatland use types, with Cd, Hg, and Pb in improved and semi-natural grassland peatsoils exceeding the World Health Organization (WHO) permissible safety limits. Contamination factors (CF) were higher in improved grassland, especially for Cd and Pb, exceeding one. Hakanson potential ecological risk assessment indicates acceptable overall risk levels, though variations exist between improved grassland, unimproved grassland, forest, and industrial cutaway bog. Combined exposure routes (dermal, ingestion and inhalation routes) to all heavy metals do not exceed safe exposure levels (indicating low non-carcinogenic risks. However, the cancer risk (CR) exceeds acceptable thresholds across all use types, with higher CR in improved grassland, especially for children. Overall, the findings emphasize the need for careful consideration of heavy metal risks associated with land use changes in peatlands, particularly in the improved grassland areas.

Spatial distribution and source identification of metal contaminants in soil and rice grain samples: a study on exploration of soil quality and risk assessment

The present study aims to assess soil quality and potential health risks associated with soil pollution of the Batala region of Punjab, India. Physico-chemical parameters such as pH (6.69-7.43), electrical conductivity (0.17-0.33 mS/cm), and total organic carbon (1.01-5.94%) were observed to be within permissible limits. The maximum mean content (mg/kg) of heavy metals in soil was found as Fe (4060.93), Zn (444.33), Mn (278.5), Pb (23.16), Cu (21.78), Ni (20.16), Co (7.14), and Cd (1.85) which were below the prescribed limits but beyond the geochemical background limits of world soil. For rice grain samples, metal content (mg/kg) was seen as Fe (307.01) > Zn (12.41) > Mn (7.43) > Cu (4.57) and was below the permissible limits. The mean bioaccumulation factor for various metals was in the order as Zn > Cu > Fe > Mn. Single and integrated soil pollution indices revealed that among 18 sites, six were highly contaminated. The ecological risk index (Er) has shown that contamination of soil with Cd, Zn, and Ni was higher than that of other metals studied. The estimated daily intake of metal (EDI), hazard quotient (HQ), and hazard index (HI) were higher for children than those for adults. Spatial variability based on metal pollution load and soil quality was also determined using cluster analysis (CA) and principal component analysis (PCA). During CA, soil samples from 18 sites formed three statistically significant clusters based on the level of metal pollution at the specific site. PCA showed that all variables were reduced into two main components 1 and 2 with eigenvalues as 3.82 (47% variance) and 1.53 (19.7% variance), respectively.

Cancer patterns in Iran: a gender-specific spatial modelling of cancer incidence during 2014-2017

BACKGROUND

Cancer is a significant public health concern and the second leading cause of death. This study aims to visualize spatial patterns of top common cancer types and identify high-risk and low-risk counties for these cancers in Iran from 2014 to 2017.

METHODS

In this study, we analyzed 482,229 newly diagnosed cancer cases recorded by the Iranian National Population-Based Cancer Registry from 2014 to 2017. We employed a purely spatial scanning model and local Moran I analysis to explore spatial patterns across Iran.

RESULTS

Approximately 53% of all cases were male. The average age of cancer diagnosis was 62.58 ± 17.42 years for males and 56.11 ± 17.33years for females. Stomach cancer was the most common cancer in men. The northern and northwestern regions of Iran were identified as high-risk areas for stomach cancer in both genders, with a relative risk (RR) ranging from 1.26 to 2.64 in males and 1.19 to 3.32 in females. These areas recognized as high-risk areas for trachea, bronchus, and lung (TBL) cancer specifically in males (RR:1.15-2.02). Central regions of Iran were identified as high-risk areas for non-melanoma skin cancers in both genders, ranking as the second most common cancer (RR:1.18-5.93 in males and 1.24-5.38 in females). Furthermore, bladder cancer in males (RR:1.32-2.77) and thyroid cancer in females (RR:1.88-3.10) showed concentration in the central part of Iran. Breast cancer, being the most common cancer among women (RR:1.23-5.54), exhibited concentration in the northern regions of the country. Also, northern regions of Iran were identified as high-risk clusters for colon cancer (RR:1.31-3.31 in males and 1.33-4.13 in females), and prostate cancer in males (RR:1.22-2.31). Brain, nervous system cancer, ranked sixth among women (RR:1.26-5.25) in central areas.

CONCLUSIONS

The study's revelations on the spatial patterns of common cancer incidence in Iran provide crucial insights into the distribution and trends of these diseases. The identification of high-risk areas equips policymakers with valuable information to tailor targeted screening programs, facilitating early diagnosis and effective disease control strategies.

Human health risk assessment of metals in soil samples of a Brazilian city with a historic contamination complex

Rio Grande is a city located on a narrow industrialized and urbanized Brazilian peninsula, characterized by wetlands. Due to population growth, numerous urban backfilled regions were built to expand the territorial area of the city. Currently, more than 60% of the central area of the city comes from the grounding of wetlands. The material used for the expansion of the territory had a history of contamination from metals from the tannery and textile industries (mainly Hg) and urban solid waste. In addition to past sources, the city has an active industrial complex with fertilizer, petrochemical, and grain industries. This study evaluated the risks to human health caused by metals (Hg, Fe, Ni, Cr, Cu, Pb, and Zn) in original soils and backfills, considering the oral, inhalation, and dermal routes of exposure for children and adults using the tool human health risk assessment (HHRA) proposed methodology by USEPA. A total of 63.81% of the original soil samples and 57.14% of the backfill soil samples showed a non-carcinogenic risk (HInc>1) for at least one evaluated metal. Still, approximately 10% of the samples presented carcinogenic risk when the Cr was considered in the hexavalent form. The dermal (Hg, Ni, and Cr) and oral (Fe, Cu, and Zn) exposure routes had the greatest contribution to the total risk. The non-carcinogenic risk for Hg, Cr(VI), and Pb was heterogeneously distributed between the original soils and backfills and associated with the proximity to some pollution sources. Given the complexity of historical occupation in the municipality and the increasing industrialization, both the original areas and the backfills should be included in the risk management strategy to minimize risks.

Ecological and health risk assessment of heavy metals in agricultural soils from northern China

Soil pollution by heavy metals can cause continuing damage to ecosystems and the human body. In this study, we collected nine fresh topsoil samples and 18 maize samples (including nine leaf samples and nine corn samples) from agricultural soils in the Baiyin mining areas. The results showed that the order of heavy metal concentrations (mg/kg) in agricultural soils was as follows: Zn (377.40) > Pb (125.06) > Cu (75.06) > Ni (28.29) > Cd (5.46) > Hg (0.37). Cd, Cu, Zn, and Pb exceeded the Chinese risk limit for agricultural soil pollution. The average the pollution load index (4.39) was greater than 3, indicating a heavy contamination level. The element that contributed the most to contamination and high ecological risk in soil was Cd. Principal component analysis (PCA) and Pearson's correlation analysis indicated that the sources of Ni, Cd, Cu, and Zn in the soil were primarily mixed, involving both industrial and agricultural activities, whereas the sources of Hg and Pb included both industrial and transportation activities. Adults and children are not likely to experience non-carcinogenic impacts from the soil in this region. Nonetheless, it was important to be aware of the elevated cancer risk presented by Cd, Pb, and especially Ni. The exceedance rates of Cd and Pb in corn were 66.67% and 33.3%, respectively. The results of this research provide data to improve soil protection, human health monitoring, and crop management in the Baiyin district.

Accumulation characteristics, driving factors, and model prediction of cadmium in soil-highland barley system on the Tibetan Plateau

Cadmium (Cd) poses major human health problems due to its high toxicity and organ bioaccumulation potential. This study collected and analysed 130 pairs of representative soil-highland barley samples on the Tibetan Plateau. The total soil Cd content (Cd-soil), available soil Cd (Cd-ava), and highland barley Cd contents (Cd-barley) ranged from 0.03 to 0.46 mg kg-1, 0.006-0.185 mg kg-1, and 0.57-13.62 μg kg-1, with mean values of 0.19 ± 0.01 mg kg-1, 0.045 ± 0.003 mg kg-1, and 4.57 ± 0.17 μg kg-1, respectively. Redundancy analysis (RDA) demonstrated that geographic factors and soil properties explained 28.46% of the variation in Cd-soil and Cd-ava, and precipitation (14.6%) and pH (9.1%) were the dominant factors. The structural equation model (SEM) indicated that Cd-soil and Cd-ava were predominantly controlled by pH. Furthermore, the Cd-soil, Cd-ava, and Cd-barley with significantly different environmental conditions were more accurately predicted by conditional inference trees-multiple linear regression (CITs-MLR). When Cd-soil is more than 0.376 mg kg-1, Cd-ava obtains the most accurate predictor (R2 =0.64, P < 0.01). This study provides new scientific insight into understanding the environmental biogeochemical nexus of Cd in the complex and fragile plateau environment and evaluating food security on the Tibetan Plateau under the self-sufficiency model of highland barley.

Spatial distribution of heavy metals in soils around cement factory and health risk assessment: a case study of Canakkale-Ezine (NW Turkey)

Sustainable use of agricultural land plays a crucial role in ensuring food security. For sustainable use of soils, it is very important to focus on the pollution status. This study was conducted on the soils in the northern part of the Ezine district in northwestern Turkey. The study aimed to determine the physicochemical properties of the soils in the vicinity of the cement plant, the concentrations of heavy metals, the spatial distribution of heavy metals, and their impact on the health of the local human population. Soil samples were collected from the cement plant in different directions (S,W, N, E, NE, SW) and at different distances (1, 3, 5, and 7 km) from 0-10 cm depth with three replicates. The soil samples were analyzed for texture, pH, electrical conductivity, lime, and heavy metals such as Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn. The soils had different textures (loam, sandy clay loam, loam, sandy loam), slightly alkaline pH, low lime content, and moderate organic matter content. Except for Cd and Pb, the average values of the other heavy metals (Co = 1.18 < 19 mg kg-1,Cr = 50.92 < 90 mg kg-1, Cu = 31.21 < 45 mg kg-1, Fe = 16,007 < 47,200 mg kg-1, Mn = 499.68 < 850 mg kg-1, Ni = 41.17 < 68 mg kg-1, Zn = 50.91 < 95 mg kg-1) in the soils were below the normal background level. The heavy metal contents of the soils in the study area are influenced by various sources (geological structure, agrochemicals used in agricultural activities, and vehicle traffic). The prevailing wind direction did not influence the local distribution of heavy metals in soils in the study area. The health risk assessment model studies showed that the hazard quotient values of less than 1 for adults and children indicate that the noncarcinogenic risks were insignificant. People exposed to heavy metals in the soils of the study area contaminated from various sources for a long time could be at carcinogenic risk. Since Cr and Pb exceed the acceptable risk range in children and Cr exceeds the acceptable risk range in adults, geochemical monitoring of soils should be conducted periodically by authorized institutions in the study area.

A review on toxic metal pollution and source-oriented risk apportionment in road dust of a highly polluted megacity in Bangladesh

Heavy metal enrichment in road dust has resulted from intensive anthropogenic activity, particularly urbanization, industrial activities and traffic emission, posing a hazard to urban ecosystems and human health. To promote optimal road dust management in urban environments, it is necessary to assess the possible ecological and health impact of toxic elements in road dust. In a heavily populated megacity like Dhaka, Bangladesh, large-scale risk assessments of contamination in road dust with heavy metals are limited. The present study aims at presenting a concentration of twenty-five metals in road dust (Na, K, Cs, Rb, Mg, Ca, Sr, Ba, Al, Zn, Cd, Pb, As, Sb, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr and W) in Dhaka megacity. We used a critical source-based positive matrix factorization model, source-oriented potential ecological risks and health risks. Out of the studied metals, Na, Ca, Zn, Cd, Cu, Zr and W exceeded the shale value. About 73%, 48%, 29% and 32% of sampling sites showed a higher level of pollution based on PLI, NIPI, PER and NIRI, respectively. PMF model identified that Cd (85.3%), Cr (62.4%), Ni (58.2%), Zn (81.8%) and Mn (65.9%) in road dust were primarily attributed to traffic emission, fuel combustion, metal processing, transport sources and natural sources, respectively. Fuel combustion and metal processing posed considerable and high risks based on modified potential ecological risk and NIRI. Based on health hazards, traffic emission posed a high cancer risk in adult males (29%), whereas transport sources contributed to females (21%) and children (23%).

Investigation of health and ecological risk attributed to the soil heavy metals in Iran: Systematic review and meta-analysis

The presence of heavy metals (HMs) in the soil can pose risks to human health via ingestion and dermal absorption. This systematic review and meta-analysis study focused on both of health and ecological risks attributed to the six HMs (As, Cd, Cr, Cu, Pb, Zn) in the soil of different Provinces of Iran. Articles were selected in the Web of Science and Scopus from 2000 to August 2021. The study was carried out according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline. Based on the inclusion and exclusion criteria, finally 32 studies were reviewed which the ranking of mean concentrations of the studied metals followed as: As > Zn > Cr > Pb > Cu > Cd. Mean concentration of Cd and As calculated via meta-analysis in the studied Provinces was found to be more than Iran's environment protection agency (EPA) guideline values. Other HMs met guideline values. A significant non-carcinogenic risk attributed to the As found in Kurdistan Province (hazard index, HI > 1). Furthermore, a significant carcinogenic health risk was found in Kurdistan and West Azerbaijan associated to As and in Fars, Khozestan and Khorasan-e-Razavi Provinces associated to Cd (ELCR >10^-4). Concerning the impact on the ecosystem, Cd, As and Pb caused ecological risks in some areas of Iran (ecological risk, ER > 40 and potential ecological risk, PER >150). Hence, we can conclude that Cd and As are important heavy metals from the health aspect. Moreover, Cd, As and Pb must be considered from an ecological point of view. Therefore, control of the Cd, As and Pb release in the environment and remediation of polluted sites through novel approaches is recommended.

Pollution Profiles, Source Identification and Health Risk Assessment of Heavy Metals in Soil near a Non-Ferrous Metal Smelting Plant

Heavy metal pollution related to non-ferrous metal smelting may pose a significant threat to human health. This study analyzed 58 surface soils collected from a representative non-ferrous metal smelting area to screen potentially hazardous heavy metals and evaluate their health risk in the studied area. The findings demonstrated that human activity had contributed to the pollution degrees of Cu, Cd, As, Zn, and Pb in the surrounding area of a non-ferrous metal smelting plant (NMSP). Cu, Cd, As, Zn, Pb, Ni, and Co pollution within the NMSP was serious. Combining the spatial distribution and Spearman correlations with principal component analysis (PCA), the primary sources of Cd, As, Pb, and Zn in surrounding areas were related to non-ferrous metal smelting and transportation activities. High non-cancer (THI = 4.76) and cancer risks (TCR = 2.99 × 10^-4) were found for adults in the NMSP. Moreover, heavy metals in the surrounding areas posed a potential cancer risk to children (TCR = 3.62 × 10^-6) and adults (TCR = 1.27 × 10^-5). The significant contributions of As, Pb, and Cd to health risks requires special attention. The construction of a heavy metal pollution management system will benefit from the current study for the non-ferrous metal smelting industry.

An experimental investigation on the effect of soluble sugar degradation on the of domestic-source-contaminated soil sites formation and evolution

The percolation-degradation process of soluble domestic pollution is very important for the evolution of soil properties and the formation of contaminated sites. The main objective of this study is to investigate the influence of glucose seepage-degradation on the permeability of clay through an indoor percolation test in combination with thermogravimetric measurement with glucose as a representative domestic contaminant soluble sugar. We can conclude that the permeability of clay was significantly impacted by the seepage-degradation of soluble sugar. With a focus on the role of soluble sugars in domestic source pollutants on clay, the formation and evolution of the domestic source contaminated soil site went through three main stages: "generation of domestic source contaminated liquid & formation of S-C zone", "contraction of S-C zone & formation of E-C zone and C zone", and "disappearance of S-C zone & contraction of E-C zone and C zone". The clay permeability decreased, the migration range shrinked, and the pollution level of the clay near the source of the contaminants increased with increasing soluble sugar solution concentration.

Contamination and Probabilistic Ecological-Health Risk of Heavy Metal(loid)s in Urban Topsoil of Mianyang, SW China

Heavy metal(loid) (HM) pollution in urban topsoil seriously endangers the health of urban residents and urban sustainable development. Compared with large cities, the research on the HM pollution of topsoil in emerging medium-sized industrial cities is quite limited. This study focuses on topsoil HM contamination in Mianyang, which is a representative moderate emerging industrial city in Southwest China. The results indicate that Ba, Cr, Cu, and Zn in the samples were much higher than their background values. The hot spots of Ba, As, Cu, Pb, Co, Cr, and Zn showed an obvious enrichment trend. The potential ecological risk of HMs showed a low ecological risk, which was mainly caused by As. The investigated HMs presented no significant non-carcinogenic hazard to local adult residents, but there were three sampling sites which presented a non-carcinogenic hazard to children; the carcinogenic risks of As, Cr, Co, and Ni were acceptable. In this study, a mixed source of industry and traffic was identified to be the priority anthropogenic source, and Cr and As were identified as the priority elements for further risk control. The findings of our study could be beneficial to decision-makers with regard to taking appropriate measures to control and reduce HM pollution in the Mianyang urban area.

Spatial distribution and source apportionment of heavy metal(loid)s in urban topsoil in Mianyang, Southwest China

Spatial distributions and sources of some commonly concerned heavy metal(loid)s (HMs, As, Ba, Cr, Co, Cu, Ni, Pb, Mn, Zn, and V) in topsoil of Mianyang city, a typical medium-sized emerging industrial city in Southwest China, were determined to explore the influences of anthropogenic activities on the urban environment. The contents of the 10 HMs in 101 topsoil samples were analyzed using an X-ray fluorescence spectrometer, and their sources were analyzed by positive matrix factorization and statistical analysis. The spatial distributions of the HMs and the source contributions were mapped using GIS technology. The results showed that the mean contents of Ba, Cr, Cu, and Zn in the topsoil were significantly higher than their background values. Industrial activities resulted in high contents of Ba, Zn, Cu, and Cr. As, Co, Ni, and V that primarily came from natural sources; Pb, Cr, Cu, and Zn were chiefly derived from a mixed source of industry and traffic; and Ba and Mn primarily originated from industrial sources. Natural sources, mixed sources, and industrial sources contributed 32.6%, 34.4%, and 33.0% of the total HM contents, respectively. Industrial sources and mixed sources of industry and traffic were the main anthropogenic sources of HMs in the urban topsoil and should be the focus of pollution control.

Geogenic and anthropogenic sources identification and ecological risk assessment of heavy metals in the urban soil of Yazd, central Iran

Urban soil pollution with heavy metals is one of the environmental problems in recent years, especially in industrial cities. The aim of this study is to evaluate the role of geogenic and anthropogenic sources in the urban soil pollution in Yazd, Iran. For this purpose, 30 top-soil (0-10 cm) samples from Yazd within an area of 136.37 Km2 and population of nearly 656 thousand are collected, and the concentration of heavy elements is measured. To evaluate factors affecting the concentration of heavy elements in urban soils and determine their possible sources, Multivariate statistical analysis, including correlation coefficient, principal components analysis (PCA) and cluster analysis (CA) are performed. Enrichment Factor (EF), Geo-accumulation index (Igeo), and Modified potential ecological Risk Index (MRI) are used to assess the level and extension of contamination. Results of this study suggest that As, Cd, Pb and Zn are affected by anthropogenic source, while the concentrations of Fe, Mn, Ni, Cr, Co, Cu and Cs have come from mostly natural geologic sources. As, Cd and Pb are considerably enriched in the area, provided moderately enriched for the elements Mn, Zn and Cu. However, the other heavy elements show minimal enrichment. Igeo reveal that Co, Cr, Cs, Cu, Fe, Mn, Zn and Ni with negative values are unpolluted, Pb posed unpolluted to moderately polluted, and As and Cd represent high polluted. Based on the results of the ecological risk factor, the heavy metals of Mn, Ni, Cr, Zn and Cu have a low ecological risk level. More specifically, we find that Pb shows a moderated ecological risk in 39% of the urban soil in the studied area. As and Cd with respectively 100 and 72% contribution have considerable and very high ecological risk. According to the results of MRI, the area is in a very high ecological risk level, and appropriate management practice is essential to reduce the pollution of heavy elements in this area.