Potential health risk of heavy metals in the leather manufacturing industries in Sialkot, Pakistan

Plants as effective bioindicators for heavy metal pollution monitoring

This study investigated the bioindicator potential of Amaranthus retroflexus L., Plantago lanceolata L., Rumex acetosa L., and Trifolium pratense L. including the use of Lolium multiflorum L. as a reference species, for heavy metal pollution monitoring, in particular Zinc (Zn), Cadmium (Cd), Nickel (Ni), and Lead (Pb). Controlled heavy metal contamination was applied through irrigation with metal nitrate solutions two levels of contamination (low and high). The study also focused on analyzing heavy metals concentration in plant tissues and related physiological responses. Distinct physiological responses to heavy metal stress were observed among the investigated species, highlighting unique variations in their reactions. Hydrogen peroxide, malondialdehyde content, and enzymatic activities emerged as reliable indicators of plant stress induced by heavy metal solutions. P. lanceolata displayed elevated Zn concentrations in both roots and leaves (3271 ± 337 and 4956 ± 82 mg kg-1). For Pb, L. multiflorum and P. lanceolata showed highest root concentrations (2964 ± 937 and 1605 ± 289 mg kg-1), while R. acetosa had higher leaf concentration (1957 ± 147 mg kg-1). For Ni, L. multiflorum had the highest root concentration (1148 ± 93 mg kg-1), and P. lanceolata exhibited the highest leaf concentration (2492 ± 28 mg kg-1). P. lanceolata consistently demonstrated the highest Cd concentrations in both roots (126 ± 21 mg kg-1) and leaves (163 ± 12 mg kg-1). These results provide valuable insights for selecting effective bioindicator species to establish control strategies for heavy metal pollution.

Cr(VI) behaves differently than Cr(III) in the uptake, translocation and detoxification in rice roots

Excessive accumulation of chromium (Cr) causes severe damage to both physiological and biochemical processes and consequently growth repression in plants. Hexavalent chromium [Cr(VI)]-elicited alterations in plants have been widely elucidated at either physiological or molecular level, whereas little is known about trivalent chromium [Cr(III)]. Here, we found that both Cr(III) and Cr(VI) significantly inhibited root growth in rice plants. However, rice plants under Cr(VI) showed significantly less inhibition in root growth than those under Cr(III) at low levels, which might be attributed to the different hormetic effects of Cr(III) and Cr(VI) on rice plants. It was unexpected that Cr(III) could be actively taken up by rice roots similarly to Cr(VI); whereas they exhibited different kinetic uptake patterns. Furthermore, root-to-shoot Cr translocation under Cr(VI) was much lower than that under Cr(III). These results indicate that the uptake, translocation, and toxicity of Cr(III) differed greatly from those of Cr(VI). Transcriptome profiling of rice roots revealed that a series of gene families involved in detoxification, including ATP-binding cassette (ABC) transporters, multidrug and toxic compound extrusion proteins (MATEs), and Tau class glutathione S-transferases (GSTUs), were significantly associated with Cr accumulation and detoxification in rice roots. In addition, much more members of these gene families were upregulated by Cr(VI) compared to Cr(III), suggesting their vital roles in Cr uptake, translocation, and detoxification, especially under Cr(VI) stress. Further comparison of gstu9 and gstu10/50 mutants with their wild type confirmed that GSTUs play complex roles in the intracellular Cr transport and redox homeostasis during Cr(III) or Cr(VI) stress. Taken together, our findings provides new insights into the differential behaviors of Cr(III) and Cr(VI) in rice roots, as well as new candidate genes such as OsABCs and OsGSTUs, to further elucidate the mechanisms of the uptake, translocation, and detoxification of Cr(III) and Cr(VI).

Unlocking the potential of biochar in the remediation of soils contaminated with heavy metals for sustainable agriculture

Agricultural soils contaminated with heavy metals (HMs) impose a threat to the environmental and to human health. Amendment with biochar could be an eco-friendly and cost-effective option to decrease HMs in contaminated soil. This paper reviews the application of biochar as a soil amendment to immobilise HMs in contaminated soil. We discuss the technologies of its preparation, their specific properties, and effect on the bioavailability of HMs. Biochar stabilises HMs in contaminated soil, enhance the overall quality of the contaminated soil, and significantly reduce HM uptake by plants, making it an option in soil remediation for HM contamination. Biochar enhances the physical (e.g. bulk density, soil structure, water holding capacity), chemical (e.g. cation exchange capacity, pH, nutrient availability, ion exchange, complexes), and biological properties (e.g. microbial abundance, enzymatic activities) of contaminated soil. Biochar also enhances soil fertility, improves plant growth, and reduces the plant availability of HMs. Various field studies have shown that biochar application reduces the bioavailability of HMs from contaminated soil while increasing crop yield. The review highlights the positive effects of biochar by reducing HM bioavailability in contaminated soils. Future work is recommended to ensure that biochars offer a safe and sustainable solution to remediate soils contaminated with HMs.

IL-6 Mutation Attenuates Liver Injury Caused by Aeromonas hydrophila Infection by Reducing Oxidative Stress in Zebrafish

Interleukin-6 (IL-6), a pleiotropic cytokine, plays a crucial role in acute stress induced by bacterial infection and is strongly associated with reactive oxygen species (ROS) production. However, the role of IL-6 in the liver of fish after Aeromonas hydrophila infection remains unclear. Therefore, this study constructed a zebrafish (Danio rerio) il-6 knockout line by CRISPR/Cas9 to investigate the function of IL-6 in the liver post bacterial infection. After infection with A. hydrophila, pathological observation showed that il-6-/- zebrafish exhibited milder liver damage than wild-type (WT) zebrafish. Moreover, liver transcriptome sequencing revealed that 2432 genes were significantly up-regulated and 1706 genes were significantly down-regulated in il-6-/- fish compared with WT fish after A. hydrophila infection. Further, gene ontology (GO) analysis showed that differentially expressed genes (DEGs) were significantly enriched in redox-related terms, including oxidoreductase activity, copper ion transport, etc. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that DEGs were significantly enriched in pathways such as the PPAR signaling pathway, suggesting that il-6 mutation has a significant effect on redox processes in the liver after A. hydrophila infection. Additionally, il-6-/- zebrafish exhibited lower malondialdehyde (MDA) levels and higher superoxide dismutase (SOD) activities in the liver compared with WT zebrafish following A. hydrophila infection, indicating that IL-6 deficiency mitigates oxidative stress induced by A. hydrophila infection in the liver. These findings provide a basis for further studies on the role of IL-6 in regulating oxidative stress in response to bacterial infections.

Contamination characteristics of heavy metals in a small-scale tanning area of southern China and their source analysis

Tanning industry has been identified as a significant source of heavy metals; however, heavy metals contamination in farmland soil due to small-scale tanning activities remains unstudied. Here, samples from topsoil, profile soil, water and sediments in the vicinity of a small-scale tanning area in Nanning, Guangxi Zhuang Autonomous Region, southern China, were collected to explore the contamination characteristics and source apportionment of Cd, Cr, Hg, As, Cu, Pb, Ni and Zn. The results show that the farmland soil was mainly contaminated by Cr and its content was 33.40-3830.00 mg kg-1. The highest level of Cr, Cd and Hg was above their thresholds, while the average contents of Cd, Cr, Pb and Hg exceeded the corresponding background levels. Moreover, enrichment of Cr in soil profiles and stream sediments were also observed, whose concentrations varied from 11.50 to 2590.00 mg kg-1 and 738.00 to 11,200.00 mg kg-1, respectively. Concentrations of Cr in top soils and soil profiles from farmland surrounding the stream were significantly higher than those from other areas, and the soils surrounding the stream were moderately to heavily polluted. The multivariate statistical analysis indicated that the heavy metals originated from traffic (Cu, Ni, Zn, Hg, and Pb), agriculture (Cr and Cd) and nature (As). Source apportionment with PMF model results showed that the relative contribution rates of heavy metals by traffic, tanning, agriculture, other industrial activities and natural sources were 16.00%, 18.88%, 20.88%, 22.04% and 22.20%, respectively. These findings indicate that small-scale tanning activities could also lead to heavy metal accumulation in the surrounding environment, which requires decision-makers to pay more attention and to develop effective remediation procedures.

Health risk assessment associated with heavy metals through fractioned dust from coal and chromite mines in Pakistan

Heavy metals exposure through dust emissions pose a health risk to workers in coal and chromite mines. The processes involved in mining are noteworthy for the generation of heavy metal-contaminated dust which causes human health implications, especially to the workers that are mainly exposed to such toxins. This study determined pollution levels in coal and chromite mines and calculated the health risk of workers being exposed to heavy metal-contaminated dust. We used fractioned dust with particle sizes < 75, 75-106, and 107-150 µm to assess the pollution levels, anthropogenic impacts, geo-accumulation index, and enrichment factor for selected coal and chromite mines. Through a probabilistic approach, Monte Carlo simulations were used to determine health risks. The findings revealed that the smallest size dust fraction (< 75 μm) contained the highest metal concentrations. Ingestion was considered a prominent exposure route contributing to health risk. In the dust fraction (< 75 μm), chromite mines exhibited the highest Cr (340.6 mg/kg) and lowest Cd (8.4 mg/kg) concentrations. In coal mines, Mn (284.9 mg/kg) and Cd (2.1 mg/kg) were measured highest and lowest, respectively. Pollution assessment revealed dust to be moderately polluted. Health risk assessment showed that Cr in chromite mines exhibited a mean HI value of 1.16E + 00 that was higher than the safe level (HI > 1) having the potential to cause significant health risk to workers. In coal mines, the estimated total HI was 6E-1. Sensitivity analysis revealed concentration and exposure time to be the most influential parameters contributing to risk. Therefore, governmental and nongovernmental organizations must develop dust pollution control guidelines and mitigation measures to safeguard the health of mineworkers by limiting heavy metal exposure.

Trace Element Levels in Nails of Residents of Addis Ababa Are Shaped by Social Factors and Geography

The Akaki catchment in Ethiopia is home to Addis Ababa and about five million people. Its watercourses receive a variety of wastes released by the residents and industries. River water is being used for irrigation, livestock watering, and other domestic purposes. This study tested the hypothesis that the river pollution would be reflected in higher levels of trace elements in the nails of residents living in Akaki-Kality Sub-City in the downstream, as compared to those living in Gullele Sub-City in the upstream of the Akaki catchment. Samples were taken and subsequently analysed for metals using inductively coupled plasma optical emission spectrometry (ICP-OES). The mean concentrations of Fe, Zn, Cu, Mn, Ni, Cr, Pb, and As in nails from Akaki-Kality were 488 ± 49, 106 ± 10, 5.2 ± 0.3, 13 ± 1.5, 11 ± 8, 2.2 ± 0.3, 0.09 ± 0.01, and 0.16 ± 0.01 μg/g, respectively. Likewise, the concentrations of Fe, Zn, Cu, Mn, Ni, Cr, Pb, and As in nails from Gullele were 1035 ± 135, 251 ± 10, 6.6 ± 0.4, 31 ± 3.7, 7.4 ± 1.7, 2.0 ± 0.3, 0.63 ± 0.01, and 0.25 ± 0.01 μg/g, respectively. Co and Cd were not detected. Contrary to the initial hypothesis, higher metal levels were found in nails of residents living in the upstream rather than the downstream area of the catchment. In particular, the concentrations of Fe (p = 0.000), Zn (p = 0.01), and Mn (p = 0.000) were significantly elevated in nails from Gullele and also high in comparison with internationally reported values. Besides, geography and social factors, especially education level, correlated to trace metals in nails. Most of the elements were significantly lower in the nails of individuals with a university degree compared to those who were illiterate or only completed primary school.

"Assessing exposure of printing factory workers in thailand to selected heavy metals using urine and hair as non-invasive matrices"

BACKGROUND

There are few thorough studies on the extent and inter-element relationships of heavy metal contamination in printing factory workers, especially in developing countries. The objective of this study was to determine the levels of eight heavy metals, including arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), cobalt (Co), lead (Pb), mercury (Hg), and manganese (Mn), in urine and scalp hair of printing industry workers, and assess inter-element correlations.

METHODS

We examined a total of 85 urine samples and 85 scalp hair samples (3 cm hair segments taken from near the scalp) in 85 printing workers from a printing house in Bangkok, Thailand. We used an interviewer-administered questionnaire about participants' printing techniques, work characteristics, and work environment. Urine and scalp hair samples were analyzed for levels of each element using the inductively coupled plasma optical emission spectrometry (ICP-OES) technique.

RESULTS

As, Cd, Cr, Ni, Pb were detected in urine with the geometric mean concentration range of 0.0028-0.0209 mg/L, and Hg, Pb, Ni, Cd, Co, Mn, Cr were detected in hair samples (0.4453-7.165 mg/kg dry weight) of printing workers. The geometric mean Ni level was significantly higher in the urine of production line workers than back-office personnel (0.0218 mg/L vs. 0.0132 mg/L; p = 0.0124). The other elements did not differ significantly between production line and back-office workers in either urine or hair. There was also a strong, statistically significant positive correlation between Ni and Co levels in hair samples of workers (r = 0.944, p < 0.0001).

CONCLUSIONS

Average concentrations of most of the metals in urine and hair of printing workers were found to be above the upper reference values. The significantly higher concentrations of Ni in production line workers might be due to more exposure to printed materials. A strong inter-element correlation between Ni and Co in hair samples can increase stronger health effects and should be further investigated. This study reveals possible dependencies and impact interactions of heavy metal exposure in printing factory workers.

Evaluation of the water quality of a highly polluted stream with water quality indices and health risk assessment methods

The water quality of Çorlu Stream, located in the Thrace region of Türkiye, and exposed to intense industrial pressure, was evaluated by monitoring 10 toxic metals and 13 other water quality variables in the dry and wet seasons of 2021. Seven different water quality indices were applied to determine the pollution level at the sampling stations in the stream. In addition, human health risks from exposure to toxic metals in stream water via ingestion and dermal contact were evaluated. The results showed that the water quality at stations S2 and S3 of Çorlu Stream receiving domestic and industrial discharges are seriously polluted by NH4-N, PO4-P, COD, BOD5 and suspended solids according to surface water quality standards. In addition, these stations were highly polluted and had poor water quality according to the results of the water quality indices. The average Cr level at station S3 exceeded the permissible levels set for the protection of aquatic life due to effluent discharges from the leather factories. Considering the results of the health risk assessment methods, non-carcinogenic risks from ingestion of combined metals in stream water can be expected at station S3 for both children and adults and at station S2 for children. Also, it was estimated that Cr and As at station S3 may cause carcinogenic health risks for residents.

Human supplementation with Pediococcus acidilactici GR-1 decreases heavy metals levels through modifying the gut microbiota and metabolome

Exposure to heavy metals (HMs) is a threat to human health. Although probiotics can detoxify HMs in animals, their effectiveness and mechanism of action in humans have not been studied well. Therefore, we conducted this randomized, double-blind, controlled trial on 152 occupational workers from the metal industry, an at-risk human population, to explore the effectiveness of probiotic yogurt in reducing HM levels. Participants were randomly assigned to two groups: one consumed probiotic yogurt containing the HM-resistant strain Pediococcus acidilactici GR-1 and the other consumed conventional yogurt for 12 weeks. Analysis of metal contents in the blood revealed that the consumption of probiotic yogurt resulted in a higher and faster decrease in copper (34.45%) and nickel (38.34%) levels in the blood than the consumption of conventional yogurt (16.41% and 27.57%, respectively). Metagenomic and metabolomic studies identified a close correlation between gut microbiota (GM) and host metabolism. Significantly enriched members of Blautia and Bifidobacterium correlated positively with the antioxidant capacities of GM and host. Further murine experiments confirmed the essential role of GM and protective effect of GR-1 on the antioxidative role of the intestine against copper. Thus, the use of probiotic yogurt may be an effective and affordable approach for combating toxic metal exposure through the protection of indigenous GM in humans.

ClinicalTrials.gov identifier: ChiCTR2100053222

Heavy metals in leathers, artificial leathers, and textiles in the context of quality and safety of use

The article presents research findings on the content of arsenic, cadmium, chromium, copper, lead, and zinc in extracts from leathers, artificial leathers intended for footwear components, and textiles. After extracting the metals using an artificial acidic sweat solution, their contents were quantitatively determined by atomic absorption spectrometry. In the cotton textiles, the metal contents were in accordance with the OEKO-TEX limits, while regarding the artificial leathers, only the acrylic knit fur had a too high chromium content (1.1 mg/kg) as compared with the requirements of the STANDARD 100 by OEKO-TEX for products intended for children (< 1.0 mg/kg). The chromium content in lining and upper leather (> 228.0 mg/kg) exceeds the limits for children’s products (< 2.0 mg/kg), but also the less restrictive ones for other products (< 200.0 mg/kg). Regarding the other metals, the leathers met the OEKO-TEX requirements. Approved materials may have elevated heavy metal contents, as demonstrated for chromium. The presence of heavy metals in too large amounts in products is a serious problem due to their allergenic and toxic effect. Therefore, action should be taken aimed at more effective detection and elimination of such products from markets and at reducing the use of chemicals containing harmful metals in manufacturing processes.

Sediment contamination by trace elements and the associated ecological and health risk assessment: A case study from a large reservoir (Turkey)

Although Keban Reservoir (KR) is Turkey's the second largest man-made reservoir, limited data are available on the contents of trace elements (TEs) in sediments of the KR. The concentrations of 23 less- and commonly-monitored TEs in the sediments from 49 sites in the reservoir were measured to assess health risks, contamination levels and ecological risks of TEs. Concerning median Enrichment Factor values of TEs, chromium (Cr), strontium (Sr) and nickel (Ni) showed moderate enrichment, while other TEs showed minimal enrichment. Pollution Load Index values ranged from 0.33 to 0.63, indicating no a multi-element contamination case in the study area. Low ecological risk was found at 47 sites, while moderate ecological risk was recorded at two sites. The PEC (probable effect concentration) values were exceeded for Ni and Cr. Although wastewater from leather processing factory partly contributed to Cr enrichment at site 2, all TEs mainly originated from lithogenic sources. Median hazard quotient (HQ) values of zirconium (Zr) and lanthanum (La) for children from sediment ingestion were above the risk threshold of unity (HQ = 4.81 and 1.39) and contributed 62.9% and 18.2% of the total health risk. Such high HQ values of Zr and La have never been reported in the literature. Hazard index values for children exceeded those for adults, indicating that children are more vulnerable to health risks than adults. Carcinogenic risk values of arsenic (As) were within the acceptable limits. Our findings indicated that in a multi-element sediment study, some less-monitored elements such as Zr and La may have an important role in health risk assessment even if they are found in the sediment at low concentrations. Therefore, this study can be a model for future similar studies evaluating the health risks of multi-elements in sediments.

First insight into the occurrence, spatial distribution, sources, and risks assessment of antibiotics in groundwater from major urban-rural settings of Pakistan

Antibiotics contamination in the water environment is a high priority global concern. Growing levels of antibiotics in freshwater resources, especially groundwater, due to anthropogenic sources such as pharmaceutical and veterinary applications, are alarming. The present study aims to investigate the occurrence, spatial distribution, source apportionment, ecological, and human health risks of antibiotics (n = 23) in groundwater samples (n = 144) of highly populated cities of Pakistan. The elevated level of antibiotics was detected in Faisalabad with the mean concentrations of 13.8 ng/L, followed by Gujrat (7.8 ng/L), Lahore (4.04 ng/L), Quetta 3.9 ng/L, Rawalpindi/Islamabad (2.29 ng/L), and Peshawar (2.03 ng/L), respectively. Out of 23 investigated antibiotics, tigecycline and ciprofloxacin were predominantly present in groundwater with average concentrations of 21.3 ng/L and 18.2 ng/L, respectively. The spatial distribution analyses revealed that among the targeted cities, Faisalabad, an industrial hub of the country, had the most polluted groundwater with dominant classes of antibiotics including quinolones (except flumequine), β-Lactams, tetracyclines, sulfonamides, and amphenicols, implying an elevated consumption of human and veterinary drugs in the city. The occurrence of targeted antibiotics varied greatly among cities (p < 0.05). PCA-MLR analysis confirmed domestic discharge (31%), animal husbandry (19%), and pharmaceutical/hospital discharge (48%) as the chief contributors to antibiotics contamination in groundwater of Faisalabad. The risk quotient (RQ) values of targeted antibiotics were reported as 1.16E-07 to 1.03E-02, and demonstrated that antibiotics pose no risks to human health, while hazard quotient (HQ) values were observed as 09.5E-05 to 6.6E-01, and only ciprofloxacin, flumequine, oxytetracycline, and sulfamethoxazole revealed moderate to low ecological risks to water species (0.1 < HQ < 1). Since, no detailed study has been conducted to evaluate the antibiotics' contamination in groundwater of Pakistan, this robust investigation provides a way forward to further explore the environmental and human health implications of antibiotics in major urban-rural settings in the region.

Methodology to Investigate Indigenous Solid Waste Systems and Practices in the Rural Areas Surrounding Maseru (Kingdom of Lesotho)

Solid waste management (SWM) is the greatest challenge facing environmental protection and human wellbeing in the rural communities of Maseru (Kingsom of Lesotho). A lack of formal waste management (WM) systems in rural areas of Maseru have resulted in different indigenous systems and practices of SWM. Direct observation and descriptive designs will be employed. This is a mixed methods study of qualitative, quantitative and, non-experimental. We obtained data sets from existing official census and statistics of Maseru. We sampled 693 participants from total population of 6917. We received ethical clearance from Research Ethics committee of Health Sciences at the University of Johannesburg, we recruited six field workers. We have preventive equipment (sanitizers, masks, and sterile latex gloves) for COVID-19 infections in place; we have specific design on caps, masks and bags that will identify field workers as they collect data. We will train field workers, administer questionnaires, interview, and observe participants. STATKON will analyse data. The research will share the results with the Ministry of Environment and the community in Lesotho. The results will also be used to educate the rural communities on improved WM. Where weaknesses are identified, mitigation measures can be evaluated and implemented to rectify the negative aspects and improve the systems and practices. The rural communities face challenges such as waste collection services and sanitation facilities and this fact points out that there is a gap in SWM, which favours the existence of indigenous systems and practice of SWM.

A Systematic Framework for Collecting Site-Specific Sampling and Survey Data to Support Analyses of Health Impacts from Land-Based Pollution in Low- and Middle-Income Countries

The rise of small-scale and localized economic activities in low- and middle-income countries (LMICs) has led to increased exposures to contaminants associated with these processes and the potential for resulting adverse health effects in exposed communities. Risk assessment is the process of building models to predict the probability of adverse outcomes based on concentration-response functions and exposure scenarios for individual contaminants, while epidemiology uses statistical methods to explore associations between potential exposures and observed health outcomes. Neither approach by itself is practical or sufficient for evaluating the magnitude of exposures and health impacts associated with land-based pollution in LMICs. Here we propose a more pragmatic framework for designing representative studies, including uniform sampling guidelines and household surveys, that draws from both methodologies to better support community health impact analyses associated with land-based pollution sources in LMICs. Our primary goal is to explicitly link environmental contamination from land-based pollution associated with specific localized economic activities to community exposures and health outcomes at the household level. The proposed framework was applied to the following three types of industries that are now widespread in many LMICs: artisanal scale gold mining (ASGM), used lead-acid battery recycling (ULAB), and small tanning facilities. For each activity, we develop a generalized conceptual site model (CSM) that describes qualitative linkages from chemical releases or discharges, environmental fate and transport mechanisms, exposure pathways and routes, populations at risk, and health outcomes. This upfront information, which is often overlooked, is essential for delineating the contaminant zone of influence in a community and identifying relevant households for study. We also recommend cost-effective methods for use in LMICs related to environmental sampling, biological monitoring, survey questionnaires, and health outcome measurements at contaminated and unexposed reference sites. Future study designs based on this framework will facilitate consistent, comparable, and standardized community exposure, risk, and health impact assessments for land-based pollution in LMICs. The results of these studies can also support economic burden analyses and risk management decision-making around site cleanup, risk mitigation, and public health education.

Risk analysis of inhaled hexavalent chromium (Cr6+) exposure on blacksmiths from industrial area

Chromium (Cr) is used as a mixture to improve strength and corrosion resistance. Milling and welding processes can expose workers to Cr through dermal exposure and inhalation. Cr exposure can be determined by urine testing. The purpose of this study was to analyze the concentration of Cr in urine (UCr) of workers. This study was carried out using a cross-sectional method. Sampling was conducted in the village of Mekarmaju, Bandung, Indonesia. The number of respondents included 30 blacksmiths, and the control group comprised 10 people who were not blacksmiths. Cr⁶⁺ exposure was measured using a personal sampling pump placed on the collar of the worker's shirt as a breathing zone and then analyzed using a UV-visible spectrophotometer. UCr was measured with a graphite furnace atomic absorption spectrophotometer. The measured Cr⁶⁺ concentration in the exposed working area ranged from 0.03 to 0.63 mg/m³, whereas that in non-exposed area ranged from 0.02 to 0.04 mg/m³. Results showed that 16 out of 30 blacksmiths had a UCr concentration above the biological exposure index (BEI) value, 21 had a higher value than the threshold limit value (TLV), and 22 had hazard index (HI) values > 1, which indicated that Cr has a hazardous potential in the body. The analysis of the exposed and control groups showed a significant difference with a p value of 0.000 for TLV, chronic daily intake, and UCr. These results clearly showed that Cr⁶⁺ exposure may harm the health of these workers in the future. The results obtained in this study can be used to promote workers' awareness on the potential health risk caused by Cr⁶⁺ exposure in the working environment.

Heavy metals in indoor dust: Spatial distribution, influencing factors, and potential health risks

Given the large proportion of time that people spend indoors, the potential health risks posed by heavy metals in the indoor environment deserve greater attention. A global-scale assessment of heavy metal contamination in indoor dust was conducted in this study based on >127 articles published between 1985 and 2019. The pollution levels, spatio-temporal variations, sources, bioaccessibilities, influencing factors, and health risks of heavy metals associated with indoor dust were analyzed. Children's blood lead levels (BLLs) were also estimated using the integrated exposure uptake biokinetic model. The results indicated that the median concentrations of Cu and Zn in 71.9% and 71.0% of the study sites surpassed the corresponding permissible limits, 100 and 300 mg/kg, respectively; thus, their control should be given priority. Heavy metal concentrations in indoor dust from different areas of the world varied greatly, which was closely associated with the type of local human activities, such as mining, melting, e-waste recycling and Pb-related industries. The bioaccessibilities of some key elements, e.g., Pb, Cd, Cu, and Zn, in household dust were high. The levels of heavy metals in indoor dust were mainly affected by a combination of outdoor and indoor sources and related critical factors, and future studies should focus on quantifying the contributions of different sources. Based on the health risk assessment, dust Pb exposure is a major health concern in e-waste recycling areas, which warrants greater attention. 49.8%, 36.8% and 14.4% of study sites showed BLLs exceeding 35 μg/L (threshold limit in Germany), 50 μg/L (threshold limit in the USA), or 100 μg/L (threshold limit in China), respectively. Finally, Pb exposure from indoor dust represents a major contributor to children's blood Pb poisoning in many developing countries. This study details the overall heavy metal contamination status of indoor dust and provides insights for policymakers with respect to pollution prevention measures.

Distribution, toxicity load, and risk assessment of dissolved metal in surface and overlying water at the Xiangjiang River in southern China

Metal pollution in drinking water source has been under scrutiny as it seriously affects human health. This work examined 12 dissolved metals in the surface and overlying water of the Xiangjiang River, an important drinking water source in southern China, and characterized their distribution, identified their possible sources, assessed their toxicity load, and determined their potential ecological and health risk. No significant difference was found in the metal concentration between surface and overlying water. The average metal concentration fell in the order of Mg > Mn > Ba > Fe > Zn > As > Sb > Ni > Cd > V > Cr > Co, and all was lower than the safety threshold in the drinking water guideline of China. Anthropogenic activities were found to be the main source of metals from correlation analysis, principal component analysis (PCA), and cluster analysis (CA). According to the total heavy metal toxicity load (HMTL), 98.20%, 71.54%, 68.88%, and 7.97% of As, Cd, Sb, and Mn should be removed from the surface water to ensure safety. Most water samples from the surveyed area were found to have high ecological risk as was measured by the ecological risk index (RI). Health risk assessment showed that children are more susceptible than adults to the non-carcinogenic risk of dissolved metals, and the potential carcinogenic risk (CR) of As and Cd should be addressed. The results provide guidance for controlling the metal pollution of the Xiangjiang River and improving its quality as a drinking water source.

Assessment of some heavy metals in crude oil workers from Kurdistan Region, northern Iraq

Heavy metal pollution in the environment has gained interest in the past few decades, as it has been found to accumulate in soil and water, as well as in the human body. Heavy metals present a serious health risk to humans when the concentration level and exposure time are increased. Although they have been extensively studied in the environment and food, little is known regarding their occurrence in the Kurdistan Region of northern Iraq. To fill this gap, we investigated the occurrence of some metals and heavy metals, namely aluminium (Al), barium (Ba), mercury (Hg), manganese (Mn), lead (Pb), vanadium (V) and zinc (Zn), in the blood of crude oil workers (40 men) who have worked in crude oil fields for at least 3 years-exposed group. In addition, a control group of 40 men was selected who have never worked or been close to crude oil fields. There is a significant correlation of metal concentrations between exposed and control groups, especially for Al, Ba, Hg, Mn and V (significant for all metals). Even though the correlation for Pb and Zn was weak, the concentrations were higher by 2-folds in the exposed group compared to the control group. Thus, the exposure caused an increase in the concentration of heavy metals by at least 1-fold in the blood of the exposed group compared to the control group. The environmental and ecotoxicological relevance of heavy metals in humans and the environment in areas with industrial activities have yet to be assessed.

Methanol, ethyl acetate and n-hexane extracts of Tragia involucrata L. leaves exhibit anxiolytic, sedative and analgesic activity in Swiss albino mice

INTRODUCTION

Tragia involucrata L. have been utilized as traditional medicine in Indian subcontinent for the treatment of numerous illnesses such as inflammation, pain and skin infection. In this current study we sought to assess the anxiolytic, sedative and analgesic activity of Tragia involucrata L. leaves extract.

MATERIALS AND METHODS

We first performed a phytochemical screening test of the leaves extracts following standard phytochemical screening protocols. We next examined the anxiolytic and sedative activity of crude methanol (TIME), ethyl acetate (TIEAE) and n-Hexane (TIHE) extract of Tragia involucrata L. leaves using mouse behavioral models such as elevated plus-maze test and pentobarbital-induced sleeping time test, respectively. Likewise, we evaluated the analgesic activity using acetic acid induced writhing test and formalin induced paw licking test. Additionally, we performed a quantitative analysis of heavy metals content of Tragia involucrata L. leaves by overnight digestion in concentrated nitric acid (HNO3).

RESULTS

Phytochemical screening demonstrated that TIME, TIEAE and TIHE contain flavonoids, alkaloids, tannins, phenols, terpenoids and sterols. Administration of these extracts resulted in higher number of open arm entry, lower number of close arm entry and higher time spent in open arm compared to control treatment (p < 0.05). Moreover, these treatments decreased the onset of sleep time and increased the duration of sleep compared to control treated mice (all p < 0.05). Likewise, extracts treated mice exhibited decreased number of writhing as well as lower acute phase and late phase duration compared to control treatment (all p < 0.05). The average level of As and Fe in Tragia involucrata L. leaves was 5.16 ± 0.012 ppm and 2.76 ± 0.015 ppm, respectively.

CONCLUSION

Results from this study support that Tragia involucrata L. leaves extracts exhibit an anxiolytic, sedative and analgesic activity in mice.

Risk assessment and evaluation of heavy metals concentrations in blood samples of plastic industry workers in Dhaka, Bangladesh

To assess the potential health risk caused by heavy metals twenty-six blood samples were collected from plastic industry workers based on ages and smoking status in Dhaka, Bangladesh. Heavy metals were analyzed with an atomic absorption spectrometer. The mean concentrations of Lead (Pb), Cadmium (Cd), Nickel (Ni), and Zinc (Zn) found in blood samples of the exposed workers were 32.78 ± 9.47, 1.08 ± 0.47, 1.42 ± 1.01, and 9.08 ± 1.95 μgL-1, respectively. The average heavy metal concentrations in blood samples of smoking workers show a narrow range of fluctuation than that of non-smoking workers. A review of different age groups of industry workers shows the workers between the ages of 26 and 40 are more likely to contaminated with Pb (35.90 ± 8.06 μgL-1) and Ni (1.61 ± 1.31 μgL-1). The higher level of Cd (1.26 ± 0.46 μgL-1) and Zn (9.91 ± 2.80 μgL-1) was found in >40 years old workers. The mean concentration in indoor dust samples of different industrial subsections reported as 40.27 ± 10.33, 3.24 ± 0.83, 18.08 ± 3.61, and 103.64 ± 8.16 mg kg-1 for Pb, Cd, Ni, and Zn, respectively. Exposed workers have relatively less critical health implications concluded from the average daily intake (ADI), hazard quotient (HQs), and hazard index (HI) values. The HI values of Pb, Cd, Ni, and Zn were reported as 2.0 × 10-2, 4.64 × 10-4, 1.62 × 10-3, and 5.49 × 10-4, respectively, which have imparted minimal risks (as HI < 1) to the health of the workers. The cancer risks of Pb, Cd, and Ni were reported as 1.46 × 10-10, 1.77 × 10-9, and 1.31 × 10-9, respectively lower than the threshold values. Therefore, the result divulged a potentially lower cancer risk compared to EPA limit value of 1 × 10-6 to 1 × 10-4 for exposed industrial workers.

Environmental, ecological and health risks of trace metals in sediments of a large reservoir on the Euphrates River (Turkey)

The contents of trace metals (Cd, As, Pb, Cr, Cu, Zn, Ni, Co, Mn and Fe) in sediment samples from eleven sampling sites in The Keban Dam Reservoir, which is Turkey's second biggest reservoir, were examined to evaluate spatial distribution, possible sources, contamination status and environmental, ecological and health risks of these metals. The results indicated that enrichment factor, geoaccumulation index and contamination factor values were higher at sampling sites receiving industrial and domestic wastewater discharges. Only Cr and Ni concentrations exceeded their corresponding probable effect concentrations in 47.7% and 93.2% of the samples. Ecological risk factor and ecological risk index values at all sites were <40 and <150, respectively, indicating low ecological risk in the reservoir. Cluster, correlation and factor analyses suggested that Cr and Ni originated from mixed sources of lithogenic and anthropogenic origins, while other metals mainly originated from natural sources. For children and adults, hazard quotient value of each metal from ingestion and dermal contact pathways did not exceed 1. Carcinogenic risk (CR) values of arsenic from these two exposure pathways and total CR value were within the range of acceptable risks. Thus, in terms of recreational uses, the reservoir is considered to be safe for human health.

Alkyl Thiourea Functionalised Silica for the Effective Removal of Heavy Metals from Acanthopanax senticosus Extract

Acanthopanax senticosus extract with excessive standard of Pb, Cd, Hg, and Cu was used as the research object, and the alkyl thiourea functionalised silica was used as a new heavy metal removal scavenger. The heavy metal removal process was optimised by orthogonal experiment with dynamic and static adsorption modes. Meanwhile, the content of Acanthopanax B and Acanthopanax E, the solid content, and the HPLC fingerprint similarity were used as quality monitoring indicators of Acanthopanax senticosus heavy metal removal before and after. Then, the technical adaptability of heavy metal removal by alkyl thiourea functionalised silica was evaluated. Under the optimal dynamic adsorption conditions, the average removal rates of Pb, Cd, Hg, and Cu were 91.64%, 93.04%, 81.77%, and 83.11%, respectively. Under the optimal static adsorption conditions, the average removal rates of Pb, Cd, Hg, and Cu were 82.22%, 89.95%, 81.26%, and 82.97%, respectively. During Acanthopanax senticosus extract heavy metal removal before and after, the change percentage of Acanthopanax B and Acanthopanax E was less than 2.00%, the solid content loss rate was only 0.18%, and the fingerprint similarity was over 99.9%. The method can be used to satisfy the high efficiency of selective removal of harmful elements in Acanthopanax senticosus extract and the effective composition of almost no effect; the method is simple and easy, so it can be recommended for pretreatment of heavy metals in Traditional Chinese Medicine extracts, and this way provides a new thought and research technique to decrease the contents of heavy metals.

Pollution and contamination assessment of heavy metals in the sediments of Jazmurian playa in southeast Iran

Jazmurian playa was an ephemeral lake with a large catchment in southeast Iran, which dried up over the last 10 years as a result of prolonged drought. As the lake was recipient of incoming industrial water with trace metals deposited to the sediment, the dust is the cause of environmental concern of the region and requires evaluation and better management. The aim of this study was to evaluate the environmental and ecological pollution of Jazmurian playa. Hence, 24 collected surface sedimentary samples were analyzed with ICP-OES. The environmental pollution indices including degree of contamination (Cd), geoaccumulation index (Igeo), enrichment factor (EF), pollution load index (PLI) and potential ecological risk (PER) were determined. The study revealed moderately to strongly pollution levels of Pb, Ni and Al, while Dy, Pb, Y, Yb, Sm, Te, U, Cu, Mn, Sc represented moderate pollution. The EF values indicated four sites were highly enriched with Dy, Pb and Ni. The PER results showed high risk for four sites and considerable risk for others. Cluster analysis illustrated interconnection between the contaminants and the sites with major pollution at six sites. Obviously, climate change has considerable complex environmental impacts through transformation of local water and sediment pollution problem.

Spatial pattern of the environmental exposure to tin in the vicinity of an alloy industry in Volta Redonda, Rio de Janeiro State, Brazil

Despite being widely used in industry, the literature on tin and its effects in humans is scarce, especially regarding reference values in biological indicators such as blood and urine. Similarly, environmental limits are also rare. This study sought to assess the spatial distribution of hotspots in the environmental exposure to tin in the vicinity of an alloy industry in the south region of the state of Rio de Janeiro, Brazil. The study population consisted of 74 adults. Graphite furnace atomic absorption spectrometry determined tin in all samples. Households and points around the industry were georeferenced with the use of GPS to identify the most intense tin sites. Results of the first and second campaigns ranged from 0.022 to 0.153 and 0.003 to 0.445µg m-3 for the atmospheric air, whereas such ranges were 0.64 to 1.61 and 1.97 to 8.54µg m-2 for household dust, respectively. The mean tin concentration found in the blood of the population was 3.85 ± 1.57µg L-1. In urine the value was 3.56 ± 1.88µg L-1. The kernel map showed the highest spatial concentrations of tin in household dust in the eastern region of the industry. In the first sampling, atmospheric air samples presented the most elevated concentrations in the southwest and southeast. Although the direction of the wind was northwest, potentially high risks were concentrated in the central area in the second collection. The largest hotspots were in the north, south and southeast regions; however, urine samples showed medium to high levels in the west and east regions. Regarding blood samples, the greatest difference was the absence of hotspot areas in the west. Environmental monitoring becomes necessary to better assess the exposure to tin.

Heavy metal toxicity from the leather industry in Bangladesh: a case study of human exposure in Dhaka industrial area

Activities in the Bangladeshi leather industries have the potential to cause chemical pollutions thereby deteriorating the working environments, the surrounding residential areas, or even foodstuffs. Therefore, it is important to determine the chemical exposures among the industry workers and residents of the surrounding areas who may be directly or indirectly impacted by the contaminated environment. This study focused on evaluating the hazard arising from exposure to metals due to industrial contamination. Tissue samples of hair and nails were collected from both the leather industry workers and residents in the vicinity of the industries. Using chromium as an indicator of contamination/exposure from the leather industry, it was the most significant metal contaminant for industry workers ranging from 21.85 to 483 mg/kg and for industry-neighboring residents at 6.01 to 296.16 mg/kg. Both the workers and neighboring residents were found to be excessively exposed (P < 0.05) to chromium compared with the investigated control group of people living in a distant village area which had no industrial establishments.

Potential effects of exploiting the Yunfu pyrite mine (southern China) on soil: evidence from analyzing trace elements in surface soil

Trace element contamination caused by mining is a serious environmental problem. The potential effects of exploiting the Yunfu pyrite mine (southern China) on soil were investigated by determining trace elements in 56 surface soil samples from the vicinity of the Yunfu pyrite mine. The samples were acid dissolved and measured by an inductively coupled plasma mass spectrometry (ICP-MS). Principal component analysis and hierarchical cluster analysis were used to identify factors influencing the trace element contents and possible sources of the trace elements. The degree of trace element pollution was determined using the geological accumulation index I_geo. Monte Carlo simulations were used to assess the health risks posed. The results show that (1) six factors (parent material, mining activities, ore composition, rainfall, terrain, and other inputs) strongly affected the trace element contents of the soil samples. (2) There were three groups of trace elements, according to their possible sources. One group (Cs, Ga, Ge, Hf, Nb, Rb, Ta, Th, Ti, U, and Zr) mainly originated in parent rocks. Another group (Cr, Ni, Sr, and V) was mainly supplied by industrial plants and traffic emissions. The third group (Ba, Co, Cu, Mn, Pb, and Zn) was mainly supplied through pyrite ore exploitation processes. (3) Some samples were slightly to moderately polluted with Cs, Ga, Ge, Nb, Rb, Ta, and Ti. Most samples were moderately to highly polluted with Ba, Co, Cu, Mn, Pb, and Zn. (4) Trace elements in soil pose strong non-carcinogenic and carcinogenic health risks to people (particularly children) living near the Yunfu pyrite mine.

Multiplexed Ultra-Sensitive Detection of Cr(III) and Cr(VI) Ion by FET Sensor Array in a Liquid Medium

Chromium, one of the top five toxic heavy metals ranked according to significance in public health by WHO, exists as Cr(III) which is naturally occurring or Cr(VI) which is anthropogenic in origin. The EPA specifies the maximum contaminant level in drinking water to be 10-6 M or 0.1 mg/L or 100 ppb for the total dissolved Cr. To ensure the water consumed by the population has these pollutants below the safe threshold, this report demonstrates a field effect transistor (FET) based sensor design incorporating a highly target specific ion-selective membrane combined with extended gate technology which manifests sensitivity exceeding the Nernst limit aided by the high field effect in the short gap region of extended gate technology. Characterization and repeated testing of the portable device revealed a commendable calibration sensitivity of 99 mV/log [Cr3+] and 71 mV/log [Cr6+] for Cr(III) and Cr(VI) respectively, well surpassing the Nernst limits of sensitivity and offering a detection limit lower than ion-selective electrodes (10-6 M), and comparable to the expensive benchtop laboratory instrument, ICP-MS. This report presents a robust, easy to fabricate, economic and efficient handheld biosensor to detect the chromium in a liquid sample whether it exists as Cr(III) or Cr(VI).

Influence of Different Urban Structures on Metal Contamination in Two Metropolitan Cities

The influence of urban structures and land use patterns of metropolitan cities on the distribution of contaminants is not well understood. In this study, two metropolitan cities [Jeddah (a typical corridor city) and Madinah (a typical compact city)], featuring different spreading patterns and urban structures, were selected to investigate the contamination level and potential risk caused by metals (i.e., Pb, Zn, Co, Fe, Al, Cr, Cu, Ni, and Mn) associated with urban dust. The findings of this study show that a metropolitan city with a limited variety of activities and a polar center (e.g., Madinah) displays a typical distribution pattern of metals, i.e., concentrations of metals increase gradually toward the center of the city. In contrast, a metropolitan city with multiple major activities (e.g., Jeddah) displays a different distribution pattern, controlled by multiple key actors (e.g., seaports, oil refineries, and desalination/power plants) able to shift the location of highest contamination away from the city center. The above findings are supported by the results of several contamination and health indices. In Jeddah, the highest Pb contamination was found near an oil refinery based on geoaccumulation index (Igeo), contamination factor (CF), enrichment factor (EF), and ecological risk (Ei) values; whereas, the highest Zn contamination was found near a seaport, based on EF, CF, and Ei values. However, in Madinah, the contamination indices indicate that the most contaminated locations are near the city center. The highest non-carcinogenic health risk in Jeddah was found near an oil refinery and in the city center; whereas in Madinah, it was found mainly in the city center. Although there is no significant risk of cancer due to metals associated with dust in the two cities, Cr, representing a health risk contribution of >24%, was the major contributor of non-carcinogenic health risk in the two metropolitan cities.

Evaluation of the status and the relationship between essential and toxic elements in the hair of occupationally exposed workers

Lead poisoning is a common disease in lead-acid battery manufacturing industries. Workers can be also exposed to various toxic elements present as contaminants or used as catalysts to enhance batteries' performances. In the present study, levels of essential and toxic elements and their relationship were assessed by analyzing scalp hair samples of 52 workers in a Pb battery manufacturing plant. The impact of some confounding factors on hair mineral contents was also investigated. For comparative purposes, nonoccupationally exposed subjects were selected as controls. All elements were determined by triple quadrupole ICP-MS. The results indicated significantly higher levels of Pb, Sb, As, and Cd in the hair of workers when compared to controls (p < 0.01). The Spearman correlation test revealed significant correlations between Pb/Cr, Pb/Mn, Pb/Ni, Pb/As, Pb/Se, Pb/Sb, Hg/As, Hg/Sn, Hg/Sb, Sb/Cr, Sb/As, Sb/Se, Sb/Cd, Sb/Sn, Sn/Cr, Sn/As, Sn/Cd, Cd/As, Se/Ni, As/Cr, Ni/Cr, Ni/Mn, and Mn/Cr in the hair of workers and Pb/Cr, Pb/Mn, Pb/Ni, Pb/Cd, Mn/Ni, Mn/Cd, Cd/Ni, As/Ni, Sn/Ni, Sb/Sn, and Hg/Sn in the hair of controls. Multiple linear regression analysis revealed linear dependence including Cr = f(Pb, Ni, Sb), Mn = f(Ni, Sb), Ni = f(Mn, Cr, -Cd) (Cd was negatively correlated, β < 0), As = f(Sn, Sb, Hg), Se = f(Ni); Sn = f(As), Sb = f(As, Mn, -Hg, Sn, Se, -Ni) (Hg and Ni were negatively correlated), Hg = f(As, -Sb, Sn) (Sb was negatively correlated), and Pb = f(Cr). The result of this study can be very useful to explain the interactions between elements or for comparison studies when establishing reference ranges or monitoring elements in workplaces.