Carcinogenic Risks Of Cr Research Articles

Indoor air quality and sick-building syndrome at a metro station in Tianjin, China

Metro systems play a crucial role in public transportation worldwide. Given that metro stations are unique built environments with a significant volume of daily commuters, ensuring a satisfactory air quality in these spaces becomes paramount. This study involved measurements of indoor air quality (IAQ), staff satisfaction, particulate matter (PM) chemical composition, and heavy metal health risks at a typical metro station in Tianjin over two seasons. Although the air exchange rate was sufficient to maintain a CO2 concentration less than 1000 ppm, the proportion of staff reporting no sick-building symptoms decreased from 83 % in spring to 25 % in winter. An average mass concentration of PM with an aerodynamic diameter smaller than 2.5 μm (PM2.5) of 68.0 ± 42.2 μg/m3 and an average PM1 mass concentration of 51.8 ± 33.3 μg/m3 were observed on the platform in winter. PM2.5 contained more metal in winter than in spring. PM2.5 in winter contained more metal in winter than in spring. With a lower relative humidity in winter, the coefficient of friction between railway wheels and rails increased, thus increasing particle emission. The carcinogenic risk of Cr on the platform was unacceptable. Moreover, the health risks induced by Ba should be investigated. The findings indicate that PM control at metro stationss, particularly on platforms in winter, should be emphasized.

Health risk of heavy metals and PAHs contaminants in goat meat de-haired with waste tyres and plastic in Calabar, Nigeria

Dehairing goat meat during processing using waste car tyres and plastic is a potential route of contaminants, hence the purpose of the study. Goat meat (muscle) samples (n = 50) collected from 3 abattoirs in Calabar, Nigeria, were analysed for heavy metals and poly aromatic hydrocarbon (PAH). The mean heavy metals in goat meat were: 0.20 ± 0.02 (Pb), 0.57 ± 0.06 (Cr), 4.31 ± 0.18 (Cd), 5.02 ± 0.54 (Ni), and 0.02 ± 0.01 (Co) mg/kg, with total PAH levels of 65.91 ng/g. The mean Cr, Cd, and Ni (mg/kg) in the meat were higher than the World Health Organization/Food and Agricultural Organization (WHO/FAO) acceptable limits for food. The dominant PAH was benzo (a) anthracene. Diagnostic ratios and PCA revealed pyrogenic and petrogenic sources as contributors of the PAHs in goat meat. The carcinogenic risk of Cr, Cd, Ni, anthracene, benzo (a) anthracene, and indeno [1, 2, 3, cd] pyrene in adults and children were greater than 10−4, indicating risk. Ni and benzo (a) anthracene were the most ingested contaminants and main carcinogenic sources in adults and children. Given the impending chronic health risks in the practice, there is a need for safer processing methods that do not further contaminant the meat.

Health Hazard Related to Fine Road Dust in Poland

Abstract Air pollution emissions from road vehicles majorly contribute to particulate pollution. This poses significant threats to the environment and human health. Road dust contains various potentially toxic elements, which, when exposed to humans, can lead to severe illnesses such as asthma, cardiovascular diseases, and cancer. This study assessed adult health risks through accidental ingestion, inhalation, and dermal contact associated with heavy metals (Cr, Cu, Ni, Pb, and Zn) in road dust (with a fraction size < 0.1 mm). The analysis covers areas between sound-absorbing screens (S), in open spaces without screens (F), and at highway/express exits (E) with different surfaces: asphalt (A) and concrete (C). Results indicate the highest health risk levels are associated with Zn in road dust in S and E areas, indicating its potential negative impact on human health. When comparing results for all metals, road dust collected from A surfaces might pose a greater health risk than C surfaces. The carcinogenic risk for Cr and Ni found in road dust collected from A and C surfaces at points S, F, and E is medium. The most significant carcinogenic risk (medium-high) is associated with Cr in road dust from A surfaces in the F area, whereas the lowest risk (low-medium) for both A and C surfaces is linked to Ni exposure in the S point. The contributions of Cr and Ni highlight the need to reduce emissions of these elements in areas surrounding heavily trafficked roads.

Source-specific health risks of PM2.5-bound toxic metals in Wuhai, a semi-arid city in northwest China

Quantifying the individual impact of each PM2.5-containing source on increasing health risk is essential for mitigating the harmful effects of atmospheric pollutants to human health. However, there remains a limited understanding of these health risks and their association with sources in semi-arid cities. To address this lack of understanding, 20 PM2.5-bound toxic metals (PTMs) were observed at six sampling sites in Wuhai, a typical semi-arid city in northwest China. The spatiotemporal variations, sources, and health risks of PTMs in Wuhai were investigated. Silicon (Si), Ca, Na, Al, Mg, and Fe were the predominant metals, accounting for 90.2 % of total metals. The contents of anthropogenic metals (Cd, Hg, and Pb) were higher during winter and autumn, whereas those of crustal metals (Si, Fe, Cu, Al, and Co) were higher during spring. The sources of PTMs in Wuhai were identified as soil sources (SS, 57.8 %), fugitive dust (FD, 23.3 %), vehicular emissions (VE, 13.4 %), metal smelting (MS, 3.9 %), and coal combustion (CC, 1.7 %). The hazard quotient of Mn and the hazard index of PTMs for children were >1, suggesting a non-carcinogenic health risk for children. The carcinogenic risk of Cr was >1 × 10−6, suggesting a Cr-associated carcinogenic risk for both adults and children in Wuhai. The main sources of non-carcinogenic risk included VE (62.5 %), SS (18.4 %), MS (11.3 %), CC (4.6 %), and FD (3.2 %). Alternatively, the main sources of carcinogenic risks included MS (53.8 %), VE (15.9 %), SS (13.9 %), CC (8.8 %), and FD (7.6 %). Overall, this study suggests that natural sources (SS and FD) are significant contributors to the health risks of PTMs in semi-arid cities. In conclusion, this study provides a comprehensive understanding of PTMs in semi-arid cities and reveals the contribution of each potential source to corresponding health risks.

Assessing Human Health Risks in Asejire Lake: Implications for Water Resources in Industrialized Ibadan, Nigeria

Human health risk assessment of Asejire Lake in densely populated and industrialized Ibadan city has been examined using Average Daily Dose (ADD), Hazard Quotient (HQ), Hazard Index (HI), Chronic daily intake (CDI) and Carcinogenic Risk (CR) calculated from the hydrochemical analysis results of Aluminum, Barium, Chromium, Copper, Iron, Manganese, Nickel, Lead and Zinc. ICP-MS laboratory technique was used from which the results of the selected trace elements were extracted. The average values of Ba, Al, Cr, Fe, Cu, Mn, Pb, Ni and Zn are: 0.08ppm, 0.39ppm, 0.001ppm, 1.41ppm, 0.004ppm, 0.068ppm, 0.004ppm, 0.002ppm and 0.035ppm respectively which are all below prescribed standards except Al and Fe. The average values of TDS, EC and pH are: 51.73ppm, 100μS/cm and 7.4 respectively which show that the water is non-saline but slightly alkaline in nature. The average values of ADD, HQ, and HI for all age groups were generally <1 falling within low chronic risk for HI. However, Values computed for children are close to unity and caution must be taken for children’s consumptions both in ingestion and derma absorption. Order of abundance of average CDI is: Fe>Al>Ba>Mn>Zn>Pb>Cu>Ni>Cr respectively. Average CR for Cr and Pb fall within 10-6 and 10-4 and above respectively and this gives a signal for cancer risk in consumption. Based on WHO background values, there are elevated values of average Contamination Factor (CF) above one for Al (2) and Fe (5) depicting some degrees of contamination in water phase and Degree of Contamination also ranged from 7 to 9 (average, 8) indicating low to moderate degree of contamination. Al and Fe sourced from the various anthropogenic and lithogenic activities contributed significantly to metal loading in the water which are of health significant.

Assessment of Potentially Toxic Elements Pollution and Human Health Risks in Polluted Farmland Soils around Distinct Mining Areas in China-A Case Study of Chengchao and Tonglushan.

This research study investigates the extent of heavy metal pollution and pollution trends in agricultural soil in mining areas during different time periods. A total of 125 soil samples were collected from two mining areas in China, the Chengchao iron mine and Tonglushan ancient copper mine. The samples were analyzed for various potentially toxic elements (PTEs). The index of geoaccumulation (Igeo), pollution index (Pi), potential ecological risk index (Eri), and hazard index (HI) were calculated to evaluate the pollution status of PTEs in the farmland around the two mining areas. The sources of PTEs were inferred by pollution distribution, and the pollution conditions of the two mining areas were compared. The results showed that the pollution of ancient copper mines was relatively severe. The main pollution elements were Cu, Cd, and As, and their average Pi values were 3.76, 4.12, and 1.84, respectively. These PTEs mainly came from mining and transportation. There are no particularly polluted elements in the Chengchao iron mine and the average Pi of all PTEs were classified as light pollution and had a wide range of sources. The findings suggest that the ancient copper mine, due to outdated mining techniques and insufficient mine restoration efforts, resulted in the spread and accumulation of PTEs in the soil over an extended period, making the farmland soil around the ancient copper mine more polluted compared to the Chengchao iron mine. In the two mining areas, there is no risk of cancer for adults and children. However, the RI values of Cr in adults and children are higher than 10-4, which indicates that the carcinogenic risk of Cr in these soils is very high. The non-carcinogenic effects of PTEs on the human body in the soil of ancient copper mine are also higher than that of the Chengchao iron mine.

Human health risk assessment of trace elements in PM10 for industrial areas in Gujarat

Introduction: The present study examines human exposure to Particulate Matter (PM10) and analyses potential health concerns in the industrial zones of Ankleshwar and Vapi in Gujarat.
 Materials and methods: For Ankleshwar and Vapi, 120 samples were collected, and characterisation was carried out to determine the concentration of NO3, SO4, NH3, K-S, Na, EC, OC, Al, Si, Fe, K, Ti, Ni, Br, Ca, Cl, Mn, Pb, Cr, Zn, S, V, and Cu in PM10 mass. The health risk from exposure to different trace elements, including both carcinogenic and non-carcinogenic, is evaluated for three distinct paths of ingestion, inhalation, and skin contact.
 Results: The Excess Cancer Risk (ECR) values for Cr and Pb for the ingestion pathway and the carcinogenic risks for Cr, Ni, and Pb for the inhalation pathway are both found to be higher than the minimal permissible threshold (1×10−6) for both children and adults for Ankleshwar and Vapi. However, for Ankleshwar and Vapi, the carcinogenic risks from dermal exposure to Cr and Pb are found to be lower than the permissible limit for both adults and children. It is observed that non-carcinogenic Hazard Index (HI) values for the skin contact and ingestion routes are less than 1 for both children and adults for Ankleshwar and Vapi. While the HI value for the inhalation pathway is found to be larger than the tolerable limit of 1 for both adults and children.
 Conclusion: For the purpose of creating sustainable cities and improving the health of the urban population, this study will provide a fundamental basis and help the governing authorities design mandatory pollution prevention and control methods, restoration plans, and systematic monitoring programmes.

Pollution Assessment and Source Analysis of Heavy Metals in Atmospheric Deposition in a Lead-zinc Smelting City Based on PMF Model

To explore the pollution characteristics and sources of heavy metals in atmospheric deposition in a typical lead-zinc smelting city, 511 effective atmospheric deposition samples from 22 points in different functional areas of a city in Henan Province were collected monthly during 2021. The concentrations and spatial-temporal distribution of heavy metals were analyzed. The geo-accumulation index method and health risk assessment model were utilized to evaluate the heavy metal pollution degree. The sources of heavy metals were quantitatively analyzed using a positive matrix factorization (PMF) model. The results showed that the average concentrations of ω(Pb), ω(Cd), ω(As), ω(Cr), ω(Cu), ω(Mn), ω(Ni), and ω(Zn) in atmospheric deposition samples were 3185.77, 78.18, 273.67, 149.50, 453.60, 810.37, 54.38, and 2397.38 mg·kg-1, respectively, which were all higher than the soil background values of Henan Province. All heavy metals except Mn had significant seasonal variation characteristics. The concentrations of Pb, Cd, As, and Cu in the industrial area with lead-zinc smelting were significantly higher than those in other functional areas, and the concentration of Zn was the highest in the residential mixed area. The results of the geo-accumulation index showed that the pollution of Cd and Pb were the most serious, followed by that of Zn, Cu, and As, which belonged to the serious-extreme pollution category. The main exposure route of non-carcinogenic risk was hand-mouth intake. Pb and As posed the greatest non-carcinogenic risk to children in all functional areas. The carcinogenic risks of Cr, As, Cd, and Ni through the respiratory system to humans were all below the threshold values. The analysis of the PMF model showed that the main sources of heavy metals in atmospheric deposition were industrial pollution sources (39.7%), transportation sources (28.9%), secondary dust sources (14.4%), incineration and coal combustion sources (9.3%), and natural sources (7.8%).

Deterioration of the quality of packaged potable water (bottled water) exposed to sunlight for a prolonged period: An implication for public health.

The exposure of bottled water to sunlight leaches heavy metals into the water, thereby deteriorating its quality and this informed the study. Three plastic bottle brands (n = 100 per brand) were exposed to sunlight for different durations. The leaching of contaminants was exposure duration dependent. The following ranges were recorded for temperature (26.67-29.83 °C), pH (4.73-6.12), conductivity (159.00-298.67 μs/cm), turbidity (0.92-1.22 N.T.U), TDS (98.17-192.77 mg/l), hardness (38.12-78.17 mg/l), Fe (0.01-0.57 mg/l), Mn (BDL - 0.46), Cr (BDL - 0.37 mg/l), Al (BDL - 0.53 mg/l), Cd (0.02-0.21 mg/l), Zn (1.18-9.90 mg/l), Pb (0.03-1.68 mg/l), As (BDL - 1.48 mg/l), and Ni (0.05-1.55 mg/l). Health risk evaluation in all bottled water brands revealed possible Cr, Cd, Pb, As, and Ni toxicity. The carcinogenic risk of Cr, As, and Ni, indicated potential cancer. Arsenic posed the highest non-carcinogenic risk, while Ni posed the highest carcinogenic risk in all brands after 42 days of exposure. The microbial parameters failed to meet the WHO safety limits. The exposure of bottled water to sunlight should be avoided, to ensure a healthy population.

Metal contamination in soil and vegetables around Savar tannery area, Dhaka, Bangladesh: A preliminary study for risk assessment

Monitoring of heavy metal concentrations in soil and their accumulation in vegetables grown in the newly shifted tannery area of Savar, Bangladesh, is crucial for human health. Heavy metals (i.e., Cr, Pb, Cu, Zn, Ni, and Cd) concentrations in soil and vegetable samples were determined by atomic absorption spectrophotometer (AAS). In soil, 3220 mg/kg Cr was observed, which was 32-fold greater than the WHO/FAO recommended limit. Ecological risk indices such as the contamination factor, enrichment factor, pollution load index, and geoaccumulation index showed metal levels as moderately to very highly contaminated. The non-carcinogenic risk (NCR) was found to be higher, and the carcinogenic risk (CR) exceeded the acceptable value 1 × 10−6 and posed greater risks to children than adults, especially for Cr in soil. The main exposure pathway for soil metals was 97.8–99.9% due to oral ingestion. The concentration of heavy metals especially Cr, Pb, Zn, and Cd, in vegetables was alarming as they crossed the safety limit. The calculated mean hazard index (8.71) for vegetable samples showed elevated levels of potential NCR, while CR for Cr and Cd, exceeded the acceptable limit of 1 × 10−6, indicating the probability of cancer risk to humans through the consumption of vegetables. This study revealed a to-and-fro analysis of the present scenario of the tannery area, giving importance to human health and the environment.

Chemical Speciation, Bioavailability and Human Health Risk Assessment of Metals in Surface Dust from an Industrial Cluster in India

In this study, distribution of metals in different geochemical forms, their mobility and bioavailability in bulk surface dust samples of Bhiwadi industrial cluster (BIC) in Rajasthan, India, was assessed by modified Community Bureau of Reference (m-BCR) sequential extraction procedure. Potential risk of metals in surface dust to environment and human health was evaluated using Contamination factor (Cf), Mobility Factor (MF) and Risk Assessment Code (RAC), and carcinogenic and non-carcinogenic health risk. Residual fraction contained significant amount of metals as Cd(55.86%), Cr(86.05%), Fe(90.06%), Mn(69.94%), Ni(66.08%), and V(71.80%). Pb(52.43%) was present in reducible fraction, while Cu was equally distributed in reducible (27.66%) and oxidizable (28.20%) fractions. Zn was equally distributed in acid exchangeable (33.15%) and reducible (35.01%) fractions. High Cf values were observed for Zn (1.32-16.98), followed by Pb (0.38-11.23) and Cu (0.26-8.22). RAC indicated high risk of Cd, Mn, Ni and Zn to environment due to their high mobility and toxic nature. Zn, Pb, Cu and Cd showed highest mobility (potential bioavailability) in samples collected around metal casting, electroplating, and automobile part industries. Data indicated that metals can bio-available with the changes in redox conditions in environment. Ingestion was major pathway for carcinogenic and non-carcinogenic health risks followed by dermal and inhalation. Hazardous Index value (6.32) indicated higher susceptibility of children for non-carcinogenic risk as compared to adults. Carcinogenic risk of Cr, Cd, Ni and Pb was higher than acceptable levels in surface dust, suggesting a high risk of cancer to exposed population.

Contamination And Health Risk Assessment Of Heavy Metals Form A Typical Pb-zn Smelter In Northwest China

Soil contamination by heavy metals due to metal smelting activities poses a serious threat to the ecological environment and to human health, as it is considered to be one of the most significant sources of soil pollution. The objective of this study was to analyze the pollution status and human health risks of heavy metals emitted from metal smelting activities of a Pb-Zn smelter. The results of mean values of Zn, Pb, Cd, Cr, Cu and Mn should be incorporated and mention the status in respect to background value. Contamination levels of heavy metals were evaluated using the potential ecological risk index (RI). Possible human health risks were assessed using the health risk assessment model developed by the US EPA. The results showed that the soils are seriously polluted, and migrated down the soil vertical profile. The index of RI indicated a very high potential ecological risk overall in the entire study area, especially for Cd. The health risk analysis showed that adults and children are exposed to significant non-carcinogenic health risks, and there are higher non-carcinogenic health risks for children than for adults. Additionally, the carcinogenic risks of Cr were higher than those of Cd for the two population groups, and children were more susceptible than adults. These results are useful for management, prevention, control and remediation of heavy-metal contamination. Meanwhile, this research provides methods, experiences, and reference to other study of similar heavy-metal soil pollution. Bangladesh J. Bot. 51(4): 995-1015, 2022 (December) Special

Health risk assessment of heavy metals in drinking water: a case study in western cities of Mazandaran province, Iran

ABSTRACT Industrialisation and urbanisation in the world and Iran have led to high levels of heavy metal contamination in water resources. The health risk of exposure to heavy metals via drinking water in two western cities of Mazandaran province, Iran was assessed. The concentrations of arsenic (As), chromium (Cr), and lead (Pb) in 60 water samples collected from groundwater resources of the cities of Noshahr and Ramsar were determined using inductively coupled plasma mass spectrometry (ICP-MS). The carcinogenic and non-carcinogenic health risks assessment for adults, teenagers, and children were estimated in terms of hazard quotient (HQ) and lifetime cancer risk (LTCR), ‘respectively’. The average concentrations of As, Cr, and Pb in drinking water were ‘respectively’ 1.9, 21.6, and 1.8 µg/L in Noshahr and 1.2, 15.6, and 1 µg/L in Ramsar. These results showed that the concentration of metals in the studied areas were within standard ranges. The average HQs caused by exposure to Cr (0.229–0.383), As (0.200–0.333) and Pb (.016–.027) in Noshahr were lower than one. Also, the average HQ calculated due to exposure to Cr (0.151–0.253), As (0.132–0.219), and Pb (0.009–0.015) in Ramsar were within safe range. The non-carcinogenic risk of the heavy metals in Noshahr and Ramsar was in the following order: Cr > As > Pb. Based on the LTCR values, the carcinogenic risk of Cr in drinking water in the cities was higher than that of As. The LTCR values of As and Cr in drinking water for all the age groups in the cities were higher than the acceptable limit (10−5) recommended by the United States Environmental Protection Agency. The results can be helpful for health policy makers to prioritise interventions in the environmental health action plan and for people in taking protective measures such as using home water treatment devices.

The carcinogenic and non-carcinogenic risk assessment of heavy metals from the butts of smoked and non-smoked cigarettes

Cigarettes are known as the most popular tobacco in the world. The aim of this study was to evaluate the concentrations of heavy metals in smoked and non-smoked cigarette butts (CBs) from ten cigarette brands (including five Iranian brands) and human health risk assessment associated with inhalation exposure. Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was used for heavy metals measurement after CBs digestion. The results showed that the highest concentrations of heavy metals in non-smoked and smoked cigarette butts are related to Pb (0.63 ± 0.21 µg/g) and Ni (0.81 ± 1.48 µg/g), respectively. The concentration of all heavy metals in smoked CBs is significantly higher than in non-smoked. According to the results, Ni and Cd elements in 60% of Iranian brands and 80% of other brands have HI > 1, which indicates a potential non-carcinogenic risk for consumers. Also, the carcinogenic risk of Cr in all brands is higher than 1.00E-4, which indicates the carcinogenic risk of the consumer in case of continuous exposure to cigarette smoke. Heavy metals in CBs can have potential carcinogenic and non-carcinogenic effects on the health of smokers exposed to inhalation. Therefore, continuous monitoring and regulation of the ingredients of domestically produced and imported cigarettes are recommended.

Health risk assessment of heavy metal(loid)s in PM2.5 in two cities in Jilin Province, China, 2016–2020

The toxicity of particulate matter is related to its size and chemical composition. We determined 12 heavy metal(loid)s in atmospheric PM2.5 in two representative cities (Changchun and Yanji) of Jilin Province, China, over five consecutive years, 2016–2020, and assessed their inhalation risk to humans. In general, we found As and Cr to be the major carcinogens present, which pose a high carcinogenic risk (CR) to children. The CR of As was higher in Changchun (2.0 × 10−6 for children, 8.0 × 10−6 for adults) than in Yanji (1.3 × 10−6 for children, 5.0 × 10−6 for adults), while the CR of Cr was higher in Yanji (3.5 × 10−6 for children, 1.2 × 10−5 for adults) than in Changchun (2.7 × 10−6 for children, 9.1 × 10−6 for adults). Point estimates of non-carcinogenic risk of heavy metal(loid)s were low (hazard index <1). The results of this study suggest that risk managers should consider not only controlling PM2.5 concentrations when developing policies to reduce health risks, but should also pay attention to the heavy metal(loid)s present in PM2.5. Regional control strategies should include stringent regulatory measures for specific chemical components that present high health risks.

Potentially toxic elements exposure biomonitoring in the elderly around the largest polymetallic rare earth ore mining and smelting area in China

Potentially toxic elements (PTEs) can be released during mining operations and ore processing. The pollution and health risk related to PTEs in total suspended particulates (TSPs) around the largest polymetallic rare earth mining area (Bayan Obo) and smelting area (Baotou) in Inner Mongolia, China, were evaluated. PTEs in the hair of the elderly living in these two areas and a reference area (Hohhot) were also examined. Relationships between PTEs in TSPs and hair with categorical factors (location, gender, etc.) were also modeled. Multivariate statistical analyses were carried out to analyze the possible sources of the PTEs in TSPs. The bubble maps of the concentrations of PTEs indicated that high concentrations of PTEs were near the industrial area where smelting plants and power plants were located. In addition, health risks were assessed for adults in the mining and smelting area. The carcinogenic risk of Cr was high for residents in the study areas. Also, the residents were exposed to a non-carcinogenic risk of Ni. Significant mean value differences were observed between PTEs in the hair of the elderly in Baotou and Hohhot. Results of the linear regression model indicated that around 31 % of the Pb in hair could be explained by the linear regression model, it could be affected by Ni and Zn in TSPs, but location, gender, and sampling time showed no significant contribution. Age was not significantly associated with the PTEs levels in hair in Baotou and Bayan Obo. The results provide important scientific evidence for a better understanding of the effects of PTEs in TSPs in polymetallic ore mining and smelting areas.

Concentration, Health Risk, and Hydrological Forcing of Heavy Metals in Surface Water Following Water-Sediment Regulation of the Xiaolangdi Dam in the Yellow River.

Water and sediment regulation aimed at aquatic ecosystems and preserving reservoir capacity to minimize the negative consequences of dams can fundamentally change the distribution of heavy metals (HMs) in the reservoir and downstream reaches. However, the effects of water and sediment regulation on variation in HMs are still poorly understood. In this study, the variations in concentration, contamination, human health risk, potential sources, and influencing factors of the metalloid As and HMs (Cr, Hg, Ni, Pb, and Zn) in surface water in the reservoir and the downstream reach of the Xiaolangdi Dam (XLD) following the operation of the water-sediment regulation scheme (WSRS) were determined. These results indicate that HM concentrations in the two post-WSRS seasons were much lower than the water quality standards, but were significantly increased over time due to the trapping effects of the XLD (p < 0.05, except for Zn). However, As concentration in the reservoir was significantly lower than that observed in downstream reaches, likely due to anthropogenic input from agricultural activities. Meanwhile, HM concentrations varied with distance to the dam, which displayed a distinct accumulation closer to the dam in the post-WSRS II season. The contamination of HMs, the carcinogenic risk of exposure to As, and the noncarcinogenic risks associated with exposure to Hg, Ni, Pb, and Zn via the direct ingestion pathway of drinking water were all within acceptable levels following the WSRS, but increased over time. The carcinogenic risk of Cr in the post-WSRS II season was at an unacceptably high level, particularly at sites near the dam. Hydrological characteristics (water level and flow rate) were the dominant factors in determining the distribution of HMs. These results can provide new insight for a better understanding of the variations in HMs following the water and sediment regulation practices, and guide future management in regulating the trapping effects of dams.

Assessment of Bioaccessibility and Health Risks of Toxic Metals in Roadside Dust of Dhaka City, Bangladesh

Spatial variations in the bioaccessibility and health risks induced by chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As) and lead (Pb) in roadside dust from different land-use areas, i.e., commercial areas (CA), planned residential areas (PRA), spontaneous residential areas (SRA) and urban green areas (UGA) in Dhaka city, Bangladesh, were investigated. An in vitro simple bioaccessibility extraction test (SBET) method, which allows the simulation of the gastric (GP) and intestinal phases (IP) of human digestion, was applied to evaluate bioaccessibility and human health risk, assessed using United States Environmental Protection Agency (U.S. EPA) modelling. The average bioaccessible concentration of Zn was the highest in both the gastric (74.4–244.5 µg/g) and intestinal phases (74.4–244.5 µg/g) in all the land-use areas except UGA. The bioaccessibility percentages of Co and Cu in the IP phase and As in the GP phase were &gt;40% for all the land-use categories. Carcinogenic (Cr, Ni, As and Pb) and non-carcinogenic human health risks were evaluated for the ingestion pathway, in both children and adults. The results suggest that there were no non-carcinogenic risks for adults and children exposed to roadside dust toxic metals, but the risk levels of roadside dust toxic metals in some sampling areas were high. The carcinogenic risks of Cr in SRA (for children) and Ni in CA (for both adults and children), PRA (for children) and UGA (for children) were found to be within a tolerable range of 10−6 to 10−4.

Pollution Characteristics and Health Risk of Heavy Metals in Fugitive Dust Around Zhaotong City

In order to explore the pollution characteristics and health risks of heavy metals in fugitive dust around the urban areas of Zhaotong City, road dust and soil dust samples were collected in the Zhaoyang District of Zhaotong City in May 2019. The dust samples were suspended using a particle resuspension system to obtain PM2.5 (particulate matter with an aerodynamic diameter less than or equal to 2.5 μm). The concentrations of Ca, Al, Fe, Mg, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb in PM2.5 were quantified by ICP-MS and ICP-OES. By analyzing 10 types of heavy metals in PM2.5, the results showed that the average concentration of Mn was the highest in the soil fugitive dust, followed by Cr, Ni, Zn, Cu, Co, Pb, V, As, and Cd. The average concentration of Zn in the road fugitive dust was the highest, followed by Mn, Cu, Cr, Pb, Ni, As, Co, V, and Cd. The enrichment factor (EF) indicated that Cd was strongly enriched in the two types of fugitive dust. The EFs of Cu, Zn, and Pb in road fugitive dust showed a moderate enrichment, and they were higher than those in soil fugitive dust. Correlation and principal component analysis showed that heavy metals in the two types of fugitive dust were affected by coal burning sources. At the same time, heavy metals in soil fugitive dust were affected by agricultural activity sources, and heavy metals in road fugitive dust were affected by traffic sources. The results of the health risk assessment indicated that the carcinogenic risks of Cr, Co, Ni, As, and Cd in soil fugitive dust were higher than those in road fugitive dust. The non-carcinogenic risks of heavy metals in the two types of fugitive dust for children were higher than those for adults, and the non-carcinogenic risks of Cu, Zn, and Pb in road fugitive dust were higher than those in soil fugitive dust.

Source Apportionment and Health Risk Assessment of Heavy Metals in PM2.5 in Handan: A Typical Heavily Polluted City in North China

In order to determine the pollution sources and human health risks of metal elements in PM2.5, samples were collected by a large flow particulate matter sampler in the four seasons in 2013, 2015, and 2017 (January, April, July, and October). The mass concentrations of 10 metals (Ti, V, Cr, Mn, Ni, Cu, Zn, As, Cd, and Pb) were analyzed. The sources of heavy metals were identified by Unmix, and the potential non-carcinogenic/carcinogenic risk was evaluated. The influences of local and regional sources were also explored during the high-carcinogenic risk period (HCRP). The wind field and 72 h backward trajectories were performed to identify the potential local and regional sources in HCRP. The results showed that the average annual concentrations of PM2.5 in the urban area of Handan city were 105.14, 91.18, and 65.85 μg/m3 in 2013, 2015, and 2017, respectively. The average daily concentrations of the metals in PM2.5 in January were higher than that of April, July, and October. The average mass concentrations of the 10 heavy metal elements in PM2.5 were 698.26, 486.92, and 456.94 ng·m−3 in 2013, 2015, and 2017, respectively. The main sources of the metals in PM2.5 were soil dust sources, vehicular emissions, coal burning, and industrial activities. The carcinogenic risks of Cr and As were above 1 × 10−6 over the three years. Wind direction analysis showed that the potential local sources were heavy industry enterprises and the economic development zone. The backward trajectory analysis indicated that PM2.5 long transported from Shandong, Henan, and the surrounding cities of Handan had quite an impact on the heavy metals contained in the atmosphere of the studied area. The health risk assessment results demonstrated that the trend for non-carcinogenic risk declined, and there was no non-carcinogenic risk in 2017. However, the carcinogenic risk levels were high over the three years, particularly in January.