Human and ecotoxicological risk assessment of heavy metals in polymer post treatment sludge from Barekese Drinking Water Treatment Plant, Kumasi

The disposal of polymer post-treatment sludge (PTS) from Barekese Water Treatment Plants (WTPs) as organic fertilizer and aquatic feed is a common practice in Ghana, necessitating a thorough evaluation of its ecological and human health risks. This study aims to assess the suitability of PTS samples for soil amendment and fish feed, scrutinizing potential hazards to consumer health and soil. PTS samples were collected from five distinct lateral sections of three clariflocculator tanks. Potentially toxic metals such as Cd, Zn, Pb, Cu, Ni, and Cr were determined using a flame atomic absorption spectrophotometer. The mean concentration of 7.82 ± 2.43, 0.31 ± 0.021, and 0.78 ± 0.042 mg/kg for Mn, Zn, and Pb respectively. The concentrations of Ni, Cr, and Cd were below their detection limits (BDL) in all PTS samples. Upon detailed exposure assessment, ingestion emerged as the primary exposure route for both adults and children, with non-cancer risks (NCR) determined to be below 1 for both age groups. Additionally, an exploration of potential cancer risks (CR) associated with heavy metal exposure in the PTS samples revealed values below the tolerable intake levels ranging from 10-4 to 10-6 for both adults and children (10-8 and 10-9, respectively). This study also employs various ecological indices, such as Nemerow's synthetic pollution index (PN), single factor pollution index (PI), geo-accumulation index (Igeo), contamination factor (CF), potential ecological risk index (PERI), pollution load index (PLI), polymetallic contaminant index (IPD), and ecological risk index (ERI). These indices consistently highlight a low contamination status and ecological sensitivity. Consequently, the study indicates that the presence of metals in the PTS samples does not pose a significant threat to the surrounding environment and human health. Furthermore, this research underscores the inadequacy of relying solely on regulatory limit values in assessing the health risks of waste materials. Such comprehensive assessments are crucial for safeguarding aquatic and human populations.

Toxic metals and essential trace elements in placenta and their relation to placental function

INTRODUCTION

Placental function is essential for fetal development, but it may be susceptible to malnutrition and environmental stressors.

OBJECTIVE

To assess the impact of toxic and essential trace elements in placenta on placental function.

METHODS

Toxic metals (cadmium, lead, mercury, cobalt) and essential elements (copper, manganese, zinc, selenium) were measured in placenta of 406 pregnant women in northern Sweden using ICP-MS. Placental weight and birth weight were obtained from hospital records and fetoplacental weight ratio was used to estimate placental efficiency. Placental relative telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) were determined by quantitative PCR (n = 285). Single exposure-outcome associations were evaluated using linear or spline regression, and joint associations and interactions with Bayesian kernel machine regression (BKMR), all adjusted for sex, maternal smoking, and age or BMI.

RESULTS

Median cadmium, mercury, lead, cobalt, copper, manganese, zinc, and selenium concentrations in placenta were 3.2, 1.8, 4.3, 2.3, 1058, 66, 10626, and 166 μg/kg, respectively. In the adjusted regression, selenium (>147 μg/kg) was inversely associated with placental weight (B: -158; 95 % CI: -246, -71, per doubling), as was lead at low selenium (B: -23.6; 95 % CI: -43.2, -4.0, per doubling). Manganese was positively associated with placental weight (B: 41; 95 % CI: 5.9, 77, per doubling) and inversely associated with placental efficiency (B: -0.01; 95 % CI: -0.019, -0.004, per doubling). Cobalt was inversely associated with mtDNAcn (B: -11; 95 % CI: -20, -0.018, per doubling), whereas all essential elements were positively associated with mtDNAcn, individually and joint.

CONCLUSION

Among the toxic metals, lead appeared to negatively impact placental weight and cobalt decreased placental mtDNAcn. Joint essential element concentrations increased placental mtDNAcn. Manganese also appeared to increase placental weight, but not birth weight. The inverse association of selenium with placental weight may reflect increased transport of selenium to the fetus in late gestation.

Removal of toxic metals from sewage sludge by EDTA and hydrodynamic cavitation and use of the sludge as fertilizer

Sewage sludge (SS) is rich in plant nutrients, including P, N, and organic C, but often contains toxic metals (TMs), which hinders its potential use in agriculture. The efficiency of removal of TMs by washing with ethylenediamine tetraacetate (EDTA), in combination with hydrodynamic cavitation (HC) and the usability of washed sewage sludge as fertilizer were investigated. The environmental risk was assessed. During 8 wash batches an average 35, 68, 47 and 45 % of Pb, Zn, Cd and Cu, respectively, as well as 22 and 5 % Mn and Fe were removed from the SS. The process solutions and EDTA were recycled at a pH gradient of 12.5-2, which was achieved by adding quicklime (CaO) and then acidification by H2SO4, so that no wastewater was produced, only solid waste (ReSoil® method). The quality of the recycled process solutions (they remained unsaturated with salts) and the efficiency of the washing process were maintained across all batches. On average, 46 % of the EDTA was lost during the process and was replenished. The initial leachability of EDTA-mobilized Pb, Zn, Cu, Cr and Fe remaining in the washed SS increased 6-, 17-, 3-, 11- and 11-fold, respectively, but not to hazardous levels except for Zn. After washing, P and K remained in the SS, plant-available P increased 3.3-fold, while total N and C were reduced by 20.28 and 2.44 %, respectively. Washed SS was used as fertilizer in the pot experiment. The yield of Brassica juncea did not improve, the uptake of TMs by the plants and the leaching of TMs from the soil were minimal. Our study highlighted the drawbacks and potential feasibility of the new SS washing method.

Growth-dependent cr(VI) reduction by Alteromonas sp. ORB2 under haloalkaline conditions: toxicity, removal mechanism and effect of heavy metals

Bacterial reduction of hexavalent chromium (VI) to chromium (III) is a sustainable bioremediation approach. However, the Cr(VI) containing wastewaters are often characterized with complex conditions such as high salt, alkaline pH and heavy metals which severely impact the growth and Cr(VI) reduction potential of microorganisms. This study investigated Cr(VI) reduction under complex haloalkaline conditions by an Alteromonas sp. ORB2 isolated from aerobic granular sludge cultivated from the seawater-microbiome. Optimum growth of Alteromonas sp. ORB2 was observed under haloalkaline conditions at 3.5-9.5% NaCl and pH 7-11. The bacterial growth in normal culture conditions (3.5% NaCl; pH 7.6) was not inhibited by 100 mg/l Cr(VI)/ As(V)/ Pb(II), 50 mg/l Cu(II) or 5 mg/l Cd(II). Near complete reduction of 100 mg/l Cr(VI) was achieved within 24 h at 3.5-7.5% NaCl and pH 8-11. Cr(VI) reduction by Alteromonas sp. ORB2 was not inhibited by 100 mg/L As(V), 100 mg/L Pb(II), 50 mg/L Cu(II) or 5 mg/L Cd(II). The bacterial cells grew in the medium with 100 mg/l Cr(VI) contained lower esterase activity and higher reactive oxygen species levels indicating toxicity and oxidative stress. In-spite of toxicity, the cells grew and reduced 100 mg/l Cr(VI) completely within 24 h. Cr(VI) removal from the medium was driven by bacterial reduction to Cr(III) which remained in the complex medium. Cr(VI) reduction was strongly linked to aerobic growth of Alteromonas sp. The Cr(VI) reductase activity of cytosolic protein fraction was pronounced by supplementing with NADPH in vitro assays. This study demonstrated a growth-dependent aerobic Cr(VI) reduction by Alteromonas sp. ORB2 under complex haloalkaline conditions akin to wastewaters.

Determining priority control toxic metal for different protection targets based on source-oriented ecological and human health risk assessment around gold smelting area

Determining the priority control source and pollutant is the key for the eco-health protection and risk management around gold smelting area. To this end, a case study was conducted to explore the pollution characteristics, source apportionment, ecological risk and human health risk of toxic metals (TMs) in agricultural soils surrounding a gold smelting enterprise. Three effective receptor models, including positive matrix factorization model (PMF), ecological risk assessment (ERA), and probabilistic risk assessment (PRA) have been combined to apportion eco-human risks for different targets. More than 95.0% of samples had a Nemerow pollution index (NPI) > 2 (NPImean=4.27), indicating moderately or highly soil TMs contamination. Four pollution sources including gold smelting activity, mining source, agricultural activity and atmosphere deposition were identified as the major sources, with the contribution rate of 17.52%, 44.16%, 13.91%, and 24.41%, respectively. For ecological risk, atmosphere deposition accounting for 30.8% was the greatest contributor, which was mainly loaded on Hg of 51.35%. The probabilistic health risk assessment revealed that Carcinogenic risks and Non-carcinogenic risks of all population were unacceptable, and children suffered from a greater health risk than adults. Gold smelting activity (69.2%) and mining source (42.0%) were the largest contributors to Carcinogenic risks and Non-carcinogenic risks, respectively, corresponding to As and Cr as the target pollutants. The priority pollution sources and target pollutants were different for the eco-health protection. This work put forward a new perspective for soil risk control and management, which is very beneficial for appropriate soil remediation under limited resources and costs.

An original strategy and evaluation of a reaction mechanism for recovering valuable metals from zinc oxide dust containing intractable germanide

A novel leaching-roasting-leaching strategy was used to recover valuable metals from zinc oxide dust containing intractable germanide. In the ultrasonic enhanced oxidation leaching stage, potassium permanganate and ultrasonication were introduced to strengthen the dissolution of sulphide. During the roasting stage, sodium carbonate and magnesium nitrate were added to promote the reaction between the insoluble tetrahedral germanium dioxide and complex forms of germanium-containing compounds. Simultaneously, the sulphur produced in the ultrasonic enhanced oxidation leaching stage was used to change the phases of tin dioxide and zinc ferrite, thereby releasing germanium into its lattice. Finally, the germanium in the roasting slag was recovered by conventional leaching, and the grades of lead and tin in the residue were enriched to 35.21% and 11.31%, respectively. Compared with the conventional acid leaching process of enterprise, the total reaction time of this method was shortened to 80 min, and the recovery rates of zinc and germanium increased by approximately 10% and 40%, respectively. The entire process is clean and environmentally friendly and does not cause adverse effects on the recovery of lead and tin. Overall, this study provides new insights into the design of valuable metal recovery methods for zinc oxide dust containing intractable germanide.

Enhanced bioelectroremediation of heavy metal contaminated groundwater through advancing a self-standing cathode

Hexavalent chromium (Cr(VI)) contamination in groundwater poses a substantial global challenge due to its high toxicity and extensive industrial applications. While the bioelectroremediation of Cr(VI) has attracted huge attention for its eco-friendly attributes, its practical application remains constrained by the hydrogeochemical conditions of groundwater (mainly pH), low electron transfer efficiency, limitations in electrocatalyst synthesis and electrode fabrication. In this study, we developed and investigated the use of N, S co-doped carbon nanofibers (CNFs) integrated on a graphite felt (GF) as a self-standing cathode (NS/CNF-GF) for the comprehensive reduction of Cr(VI) from real contaminated groundwater. The binder free cathode, prepared through electro-polymerization, was employed in a dual-chamber microbial fuel cell (MFC) for the treatment of Cr (VI)-laden real groundwater (40 mg/L) with a pH of 7.4. The electrochemical characterization of the prepared cathode revealed a distinct electroactive surface area, more wettability, facilitating enhanced adsorption and rapid electron transfer, resulting in a commendable Cr(VI) reduction rate of 0.83 mg/L/h. The MFC equipped with NS/CNF-GF demonstrated the lowest charge transfer resistance (Rct) and generated the highest power density (155 ± 0.3 mW/m2) compared to control systems. The favorable electrokinetics for modified cathode led to swift substrate consumption in the anode, releasing more electrons and protons, thereby accelerating Cr(VI) reduction to achieve the highest cathodic coulombic efficiency (C.Eca)of80 ± 1.3 %. A similar temporal trend observed between Cr(VI) removal efficiency, COD removal efficiency, and C.Eca, underscores the effective performance of the modified electrode. The reusability of the binder free cathode, exemption from catholyte preparation and the absence of pH regulation requirements highlighted the potential scalability and applicability of our findings on a larger scale.

Evaluation of the toxic metals, proximate composition and length-weight relationships of selected fish species from the Gadananathi River, Southern Tamil Nadu

The present study reveals toxic metals, proximate composition, and growth conditions in seven fish species, aiding their nutritional importance and conditions. The samples of seven different small indigenous fish species, including Xenentodon cancila, Glossogobious giuris, Pseudambassis ranga, Puntius dorsolis, Mystus vittatus, Dawkinsia filamentosa, and Dawkinsia tambraparaniei, were collected in river Gadananathi, Tamilnadu, India. A total 14 fish samples were analyzed for lead, cadmium, and copper using atomic absorption spectrometry. The standard procedures were used to determine the length-weight and proximate composition of the seven fishes. The findings revealed that the seven fish species had variable amounts of metal buildup. Cu levels were highest in D. tambraparniei gills and lowest in M. vittatus gills and livers; nonetheless, substantial amounts of Cu were found in P. dorsalis livers. In the length-weight correlations of the regression parameters of coefficient value r2, the "a" and "b" values revealed a positive allometric growth rate in all fish species except G. giuris and M. vittatus. However, X. cancila had the highest composition in the proximate analysis, while D. tambraparniei and D. filamentosa had the highest protein content mean value at a significant level (P ≤ 0.05). Overall, discrepancies in nutritional content might be related to species, environmental circumstances, fish age and size, and food availability.

Relationships between high-concentration toxic metals in sediment and evolution of microbial community structure and carbon-nitrogen metabolism functions under long-term stress perspective

Microorganisms are highly sensitive to toxic metal pollution and play an important role in the material cycling and energy flow of the water ecosystem. Herein, 13 sediment samples from Junchong Reservoir (Guangxi Province, China) were collected in December 2021. The spatial distribution of pollution levels for toxic metals and the effects of toxic metals on the composition, functional characteristics, and metabolism of microorganisms were investigated. The results demonstrated that the area is a proximate area to industrial zones with severity of toxic metal pollution. Their mean concentrations of As, Cu, Zn, and Pb were up to 128.79 mg/kg, 57.62 mg/kg, 594.77 mg/kg, and 97.12 mg/kg respectively. There was a strong correlation between As, Cu, Zn, and Pb, with the highest correlation coefficient reaching 0.94. As the level of toxic metal pollution increases, the diversity and abundance of microorganisms gradually decrease. Compared to those with lower pollution levels, the Shannon index in regions with higher pollution levels decreases by up to 0.373, and the Chao index decreases by up to 143.507. However, the relative abundance of Bacteroidota, Patescibacteria, and Chloroflexi increased by 23%, 20%, and 5%, respectively, indicating their higher adaptability to toxic metals. Furthermore, microbial carbon and nitrogen metabolism were also affected by the presence of toxic metals. FAPROTAX analysis demonstrated an abundant reduction of ecologically functional groups associated with carbon and nitrogen transformations under high toxic metal pollution levels. KEGG pathway analysis indicated that carbon fixation and nitrogen metabolism pathways were inhibited with increasing toxic metal concentrations. These findings would contribute to a better understanding of the effects of toxic metal pollution on sediment microbial communities and function, shedding light on the ecological consequences of toxic metal contamination.

Polyurethane sponges bearing cucurbituril adsorb Cr(III) and Pb(II) ions from contaminated water samples

Water contamination with toxic metals causes harmful effects on the environment and to human health. Although cucurbiturils have carboxyl groups in their portal that can interact with metal ions, there is a lack of studies about their use as metal adsorbent. This scenario has motivated conduction of the present study, which addresses the use of cucurbit[6]uril (CB[6]) and cucurbit[8]uril (CB[8]) for adsorbing Pb and Cr from water samples, in free forms and immobilized in poly(urethane) sponges. The adsorption kinetics revealed that CB[8] leads to faster adsorption compared to CB[6], with equilibrium achieved in 8 h for CB[8] and 48 h for CB[6] for both metals, and achieved up to 80% of decrease in metal concentration. The Langmuir isotherm model provided a better description of adsorption for Cr and Pb in CB[6] and Pb in CB[8] with a maximum concentration adsorbed of 32.47 mg g-1 for Pb in CB[6], while the Dubinin-Radushkevich model was more suitable for Cr adsorption in CB[8]. Sponges containing CB[6] and CB[8] have proven to be efficient for Pb and Cr remediation in tannery effluent samples, reducing Cr and Pb concentration by 42 and 33%, respectively. The results indicate that CB[6] and CB[8], whether used in their pure form or integrated into sponges, exhibit promising potential for efficiently adsorbing metals in aqueous contaminated environments.

Metals concentration and human health risk assessment in some fish species from the southern Caspian Sea

The main objectives of this study were to determine the mercury concentration in four species of valuable and widely consumed fish from the Caspian Sea, to assess the health risk due to their consumption. The average mercury concentrations for Chelon saliens, Chelon auratus, Acipenser persicus and Acipenser stellatus were 32.72, 39.51, 166.87 and 81.87 μg g-1 dw, respectively. There were correlations between the mercury concentrations in the muscle of Chelon saliens and morphological parameters, but these correlations were not observed in Chelon auratus. Our comparison of the mercury values obtained in all the samples with the recommended international standards, as well as the Hazard Quotients values, indicated that there is no potential risk for the health of consumers due to exposure to mercury from consuming these fish.

Association and mediation analyses among multiple metal exposure, mineralocorticoid levels, and serum ion balance in residents of northwest China

Toxic metals are vital risk factors affecting serum ion balance; however, the effect of their co-exposure on serum ions and the underlying mechanism remain unclear. We assessed the correlations of single metal and mixed metals with serum ion levels, and the mediating effects of mineralocorticoids by investigating toxic metal concentrations in the blood, as well as the levels of representative mineralocorticoids, such as deoxycorticosterone (DOC), and serum ions in 471 participants from the Dongdagou-Xinglong cohort. In the single-exposure model, sodium and chloride levels were positively correlated with arsenic, selenium, cadmium, and lead levels and negatively correlated with zinc levels, whereas potassium and iron levels and the anion gap were positively correlated with zinc levels and negatively correlated with selenium, cadmium and lead levels (all P < 0.05). Similar results were obtained in the mixed exposure models considering all metals, and the major contributions of cadmium, lead, arsenic, and selenium were highlighted. Significant dose-response relationships were detected between levels of serum DOC and toxic metals and serum ions. Mediation analysis showed that serum DOC partially mediated the relationship of metals (especially mixed metals) with serum iron and anion gap by 8.3% and 8.6%, respectively. These findings suggest that single and mixed metal exposure interferes with the homeostasis of serum mineralocorticoids, which is also related to altered serum ion levels. Furthermore, serum DOC may remarkably affect toxic metal-related serum ion disturbances, providing clues for further study of health risks associated with these toxic metals.

Data on the characterization of seaweed, wheat bran, and other food processing byproducts as feasible biosorbents

Traditionally, biosorbents have been used to remove contaminants from polluted water, such as wastewater, landfill leachate, rainwater or drinking water. However, two alternative uses of biosorbents have been proposed relatively recently: the removal of heavy metals from fruit juices by biosorption and the use of saturated biosorbents as animal feed. Because these biosorbents are in contact with food or are used as animal feed, the concentration of contaminants in biosorbents must be known. In addition, the characterization of biosorbents is crucial because biosorbent properties affect both adsorption efficiency and the performance of full-scale biosorbent systems. This article presents data from Fourier transform infrared spectroscopy (FTIR) analysis, and the concentration of toxic metals (determined by ICP-MS) as well as pesticide residues was determined in ten biomass samples, namely, pea skins, straw, seaweed Fucus vesiculosus, wheat bran, rye bran, raspberry seeds, peat, buckwheat husks, highbush blueberry pulp, and blackcurrant pulp. Selected biomass samples were also characterized by scanning electron microscopy (SEM), nitrogen physisorption analysis, and pyrolysis-gas chromatography-mass spectrometry (Py-GC/ MS/FID) analysis.

Climate warming, environmental degradation and pollution as drivers of antibiotic resistance

Antibiotic resistance is a major challenge to public health, but human-caused environmental changes have not been widely recognized as its drivers. Here, we provide a comprehensive overview of the relationships between environmental degradation and antibiotic resistance, demonstrating that the former can potentially fuel the latter with significant public health outcomes. We describe that (i) global warming favors horizontal gene transfer, bacterial infections, the spread of drug-resistant pathogens due to water scarcity, and the release of resistance genes with wastewater; (ii) pesticide and metal pollution act as co-selectors of antibiotic resistance mechanisms; (iii) microplastics create conditions promoting and spreading antibiotic resistance and resistant bacteria; (iv) changes in land use, deforestation, and environmental pollution reduce microbial diversity, a natural barrier to antibiotic resistance spread. We argue that management of antibiotic resistance must integrate environmental goals, including mitigation of further increases in the Earth's surface temperature, better qualitative and quantitative protection of water resources, strengthening of sewage infrastructure and improving wastewater treatment, counteracting the microbial diversity loss, reduction of pesticide and metal emissions, and plastic use, and improving waste recycling. These actions should be accompanied by restricting antibiotic use only to clinically justified situations, developing novel treatments, and promoting prophylaxis. It is pivotal for health authorities and the medical community to adopt the protection of environmental quality as a part of public health measures, also in the context of antibiotic resistance management.

Identification of toxic metal contamination in surface sediments of the Xiaoqing River under a long-term perspective (1996-2020): Risks, sources and driving factors

The contamination of sediments by toxic metals poses a significant threat to both river ecosystems and human health. In this study, the geo-accumulation index (Igeo), biotoxicity evaluation method, and potential ecological risk index (RI) were employed to analyze the contamination level, biotoxicity risk, and potential ecological risk of toxic metals in surface sediments of the Xiaoqing River. To identify toxic metal sources, Spearman correlation and principal component analysis with multiple linear regression analysis (PCA-MLR) were employed. Additionally, redundancy analysis (RDA) was utilized to investigate potential driving factors affecting toxic metal accumulation in sediments. The results revealed that the levels of the five investigated metals (Cr, Pb, As, Hg, and Cd) showed constant fluctuations during the period 1996-2020. The midstream was found to be more polluted than the upstream and downstream. In the research area, Hg was identified as the primary contaminant with high levels of contamination, posing a biotoxicity risk and potential ecological risk. Pollution sources were identified for two periods: A (1996-2010) and B (2011-2020), with industrial, agricultural, traffic, and natural sources being the main contributors. During period A, industrial sources accounted for the highest proportion (40.8%), followed by agricultural sources (36.6%), and geological natural sources (22.6%). During period B, agricultural sources accounted for the highest proportion (42%), followed by industrial and traffic sources (32.4%), and geological natural sources (25.6%). The distribution of toxic metals in the basin was significantly influenced by water pH, sediment organic matter, population density, and per capita GDP. The study results provide fundamental data for preventing pollution and managing water resources contaminated with toxic metals in the sediments of the Xiaoqing River in Jinan. Additionally, it serves as a reference for analyzing related ecological and environmental issues in the basin.

Occurrence, fate, and potential impacts of wood preservatives in the environment: Challenges and environmentally friendly solutions

Wood preservation has gained global prevalence in recent years, primarily owing to the renewable nature of wood and its capacity to act as a carbon sink. Wood, in its natural form, lacks intrinsic resilience and is prone to decay if left untreated; hence, wood preservatives (WPs) are used to improve wood's longevity. The fate and potential hazards of wood preservatives to human health, ecosystems, and the environment are complex and depend on various aspects, including the type of the preservative compounds, their physicochemical properties, application methods, exposure pathways, environmental conditions, and safety measures and guidelines. The occurrence and distribution of WPs in environmental matrices such as soil and water can result in hazardous pollutants seeping into surface water, groundwater, and soil, posing health hazards, and polluting the environment. Bioremediation is crucial to safeguarding the environment and effectively removing contaminants through hydrolytic and/or photochemical reactions. Phytoremediation, vermicomposting, and sustainable adsorption have demonstrated significant efficacy in the remediation of WPs in the natural environment. Adsorbents derived from biomass waste have been acknowledged for their ability to effectively remove WPs, while also offering cost-efficiency and environmental sustainability. This paper aims to identify wood preservatives' sources and fate in the environment and present a comprehensive overview of the latest advancements in environmentally friendly methods relevant to the removal of the commonly observed contaminants associated with WPs in environmental matrices.

Stimulating bioelectric generation and recovery of toxic metals through benthic microbial fuel cell driven by local sago (Cycas revoluta) waste

Benthic microbial fuel cell (BMFC) is the most promising type of bioelectrochemical approach for producing electrons and protons from natural organic waste. In the present work, a single-chamber BMFC was used, containing sago (Cycas revoluta) waste as the organic feed for microorganisms. The local wastewater was supplemented with heavy metal ions (Pb2+, Cd2+, Cr3+, Ni2+, Co2+, Ag+, and Cu2+) and used as an inoculation source to evaluate the performance of BMFC against the toxic metal remediations. According to the experimental results, the maximum power density obtained was 42.55 mW/m2 within 25 days of the BMFC operation. The maximum remediation efficiency of the metal ion removal from the wastewater was found to be 99.30% (Ag+). The conductive pili-type bacteria species (Acinetobacter species, Leucobacter species, Bacillus species, Proteus species. and Klebsiella pneumoniae) were found in the present study during isolation and identification processes. This study's multiple parameter optimization revealed that pH 7 and room temperature is the best condition for optimal performance. Finally, this study included the mechanism, future recommendations, and concluding remarks.

Seed nano-priming with multiple nanoparticles enhanced the growth parameters of lettuce and mitigated cadmium (Cd) bio-toxicity: An advanced technique for remediation of Cd contaminated environments

Seed nano-priming can be used as an advanced technology for enhancing seed germination, plant growth, and crop productivity; however, the potential role of seed nano-priming in ameliorative cadmium (Cd) bio-toxicity under Cd stress has not yet been sufficiently investigated. Therefore, in this study we investigated the beneficial impacts of seed priming with low (L) and high (H) concentrations of nanoparticles including nSiO2 (50/100 mg L-1), nTiO2 (20/60 mg L-1), nZnO (50/100 mg L-1), nFe3O4 (100/200 mg L-1), nCuO (50/100 mg L-1), and nCeO2 (50/100 mg L-1) on lettuce growth and antioxidant enzyme activities aiming to assess their efficacy for enhancing plant growth and reducing Cd phytotoxicity. The results showed a significant increase in plant growth, biomass production, antioxidant enzyme activities, and photosynthetic efficiency in lettuce treated with nano-primed nSiH + Cd (100 mg L-1), nTiH + Cd (60 mg L-1), and nZnL + Cd (50 mg L-1) under Cd stress. Moreover, nano-priming effectively reduced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in lettuce shoots. Interestingly, nano-primed nSiH + Cd, nTiH + Cd, and nZnL + Cd demonstrated efficient reduction of Cd uptake, less translocation factor of Cd with high tolerance index, ultimately reducing toxicity by stabilizing the root morphology and superior accumulation of critical nutrients (K, Mg, Ca, Fe, and Zn). Thus, this study provides the first evidence of alleviating Cd toxicity in lettuce by using multiple nanoparticles via priming strategy. The findings highlight the potential of nanoparticles (Si, Zn, and Ti) as stress mitigation agents for improved crop growth and yield in Cd contaminated areas, thereby offering a promising and advanced approach for remediation of Cd contaminated environments.

Assessing the carcinogenic and non-carcinogenic health risks of metals in the drinking water of Isfahan, Iran

Metals are significant contributors to water pollution, posing serious threats to human health. This study aims to assess the carcinogenic and non-carcinogenic health risks associated with metals in Isfahan drinking water. Eighty water samples were randomly collected from the city's distribution network between January and March 2020-2021. Inductively coupled plasma Optical Emission Spectrometry was used to measure toxic metals, namely Pb, Cr, Cd, Ni, and As concentrations. Results revealed that the mean concentration of Ni (70.03 µg/L) exceeded the WHO reference value (70 µg/L), while the other metals were below the standard values. The average chronic daily intake order of toxic metals was Ni > Cr > Pb > As > Cd. Non-carcinogenic risk assessment through hazard quotient (HQ) and hazard index (HI) demonstrated that both THI for adults (HQingestion + HQdermal = 4.02E-03) and THI for children (HIingestion + HIdermal = 3.83E-03) were below the acceptable limit (less than 1). This indicated no non-carcinogenic risk to residents through water ingestion or dermal exposure. However, findings indicated that the ingestion route was the primary exposure pathway, with HQ values for ingestion exceeding HQ values for dermal adsorption. Carcinogenic risk assessment showed that the risk associated with As metal exceeded the acceptable limit (1 × 10-6). Therefore, implementing treatment improvement programs and appropriate control measures is essential to safeguard the health of Isfahan City residents.

Accumulation characteristics of metals in human breast milk and association with dietary intake in northeastern China

The trace elements present in breast milk play a vital role in the growth and development of infants. Nevertheless, numerous studies have reported the presence of toxic metal contamination in breast milk from various countries and regions, which poses potential risks to breastfed infants. This article aimed to investigate the characteristics of trace elements in breast milk and explore the relationship between breast milk and diet in Dalian, a coastal city in northeastern China. Breast milk samples and representative local food samples were collected from Dalian for research. The results revealed that 57 % of breast milk samples significantly exceeded the WHO safety limit (0.6 μg/L) for arsenic, with a measured mean value of 0.96 μg/L. Moreover, the levels of chromium (mean value: 2.63 μg/L) in 34 % of breast milk samples exceed the WHO recommended safety level (chromium: 1.5 μg/L). Aquatic foods accounted for 60 % to 90 % of the total intake of arsenic, cadmium, vanadium, mercury, and lead. The Spearman correlation analysis demonstrated strong positive correlations among breast milk metal elements, including copper-zinc (r = 0.68) and nickel‑chromium (r = 0.89). Furthermore, the food-to-milk accumulation factors (FMAF) of strontium, nickel, arsenic, vanadium, cadmium, and mercury were relatively low (median values <0.005). While the FMAF values for chromium and lead were higher, with median values of 0.038 and 0.07, respectively. The results indicated potential risks of the toxic metal arsenic in breast milk from Dalian, China for breastfed infants. Therefore, continuous monitoring of breast milk for toxic metals and foodborne contamination is necessary.

Metals accumulation affects bone and muscle in osteoporotic patients: A pilot study

Osteoporosis is the most common bone disease, characterized by decreased bone mineral density (BMD) and often associated to decreased muscle mass and function. Metal exposure plays a role in the pathophysiology of osteoporosis and affects also muscle quality. The aim of this study was to assess the association between metal levels in bone and muscle samples and the degeneration of these tissues. A total of 58 subjects (30 male and 28 female) was enrolled and classified in osteoporotic (OP, n = 8), osteopenic (Ope, n = 30) and healthy (CTR, n = 20) subjects, according to BMD measures. Femoral head bone samples and vastus lateralis muscle samples were collected during hip arthroplasty surgeries. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis showed increased levels of Al, Cd and Pb in OP and Ope bone tissue compared to CTR subjects (p = 0.04, p = 0.005 and p = 0.01, respectively). Whereas, increased levels of Co, Cd and Pb were measured in OP and Ope muscle tissues, compared to CTRs (p < 0.001, p = 0.02 and p = 0.01, respectively). In addition, Al, Cd and Pb levels in bone and Cd and Co levels in muscle were negatively correlated with BMD. A negative association among Co, Cd, Cr and Hg levels and muscle fibers diameter was also observed in muscle tissues. This study assessed that metal exposure can affects bone and muscle tissue quality and may contribute to the onset and progression of musculoskeletal diseases such as osteoporosis. Therefore, it is important to implement metal exposure assessment and their impact on disease development, in order to manage and prevent metal accumulation effects on bone and muscle quality.

Mining wastewater treatment technologies and resource recovery techniques: A review

Mining wastewater can have adverse effects on the ecosystem; thus, treatment before discharging into the environment is of utmost importance. This manuscript reports on the effect of mining wastewater on the environment. Moreover, the currently used, effective and commercialised mine wastewater treatment technologies such as SAVMIN®, SPARRO®, Biogenic sulphide, and DESALX® are reported in this study. These technologies integrate two or more separation processes, which have been proven to be effective for the high recovery of salts and water for reuse. Some of the technologies reported can significantly recover salts and >95% of water. Modern pilot-stage and laboratory-scale treatment systems used for the recovery and removal of metals are also reported herein. Since some treatment technologies can generate highly toxic sludge and other waste products, the management of the generated waste was also considered. Some studies have focused on the treatment of wastewater at the laboratory level using the adsorption process. Most adsorbents exhibit promising results; however, there is insufficient research on reusability, toxic sludge management, and the economic analysis of the systems. Moreover, the implementation of adsorption systems in wastewater is necessary. Furthermore, the integration of treatment systems to recover precious metals at low concentrations is desirable in addition to water reclamation to achieve circular mine water.

Migration and transformation of phosphorus and toxic metals during sludge incineration with Ca additives

The recycling and utilization of phosphorus resources in sludge is becoming increasingly important. In this study, we compared the conversion of phosphorus and toxic metal passivation effects of different Ca additives under oxygen-rich combustion conditions and elucidated their specific mechanisms of action. The experimental results indicated that four Ca-based additives improved the recovery rate of total phosphorus, and promoted the generation of stable apatite phosphorus (AP). The effect of CaCl2 and CaO was greater than that of Ca(OH)2 and CaSO4. CaCl2 promoted the formation of Ca3(PO4)2 and Ca2P2O7, and CaSO4 improved the conversion of AlPO4 to Ca(H2PO4)2 with increasing temperature. The conversion capacity of CaO on non-apatite inorganic phosphorus to AP was greater than that of Ca(OH)2, and more CaH2P2O7, Ca(PO3)2, and Ca-Al-P minerals were found. Toxic metal percentages decreased after sludge incineration with CaCl2. Compared with CaO and Ca(OH)2, the toxic metal adsorption effect of CaSO4 was more significant. The influence of Ca additives on the conversion of Zn into stable components was as follows: CaCl2 > Ca(OH)2 > CaO > CaSO4. Ca additives reduced the toxic metal contamination level and ecological risk index values, and the order of toxic metal contamination levels was Ni > Zn > Cr > Cu > Mn. The experiment confirmed the conversion of phosphorus and the toxic metal passivation effect of Ca additives during oxy-fuel combustion of sludge, which is beneficial for its resource utilization.

Spatiotemporal ecological risk evaluation and source identification of heavy metals and nutrients in the water and lake surface sediment in a protected catchment area of a volcanic lake

Indonesia has numerous lakes; however, research on the spatiotemporal sediment quality and source identification in lakes remains limited. The overaccumulation of heavy metals and nutrients in lakes severely threatens aquatic ecosystems. This study aims to identify potential sources of metallic deposits (Cu, Pb, Cr, Fe, Al, and Cd) and nutrients (TN and TP) in lake-surface sediment, utilizing enrichment factors (EF), geoaccumulation indices (Igeo), potential ecological risk indices (Er), and risk indices (RI). Multivariate statistical analyses, including principal component analysis (PCA) and Pearson's correlation analysis, were conducted to pinpoint pollution sources linked to land use. Eight sampling sites for surface sediment and water were examined in both wet and dry seasons at Menjer Lake, chosen for its diverse applications in tourism, hydropower, floating net cages, and extensive agriculture in its catchment. Correlation and PCA results indicated that Pb, Fe, and Al mainly originate from tourism, while Al, Fe, TN, and TP are associated with agriculture. The highest average loading from land use was observed in agriculture (> 0.8), floating net cages (> 0.76), and tourism (> 0.68). Furthermore, the highest loading from nutrients and all metals were TP (> 0.71) and all metals (> 0.35), respectively. Ecological risk assessment revealed low to moderately polluted EFs and Igeo in the dry season. However, Menjer Lake's Er and RI for heavy metals were generally classified as unpolluted.

Antagonistic Effects, Sources, and Distribution of Selenium and Toxic Metals in Fish from Selenium-Rich and High Cadmium Areas, Dashan Region, China

The Gongxin River is one of the main rivers in the Dashan Region of Anhui Province in China, which is a Se-rich and high-Cd area, but no research has focused on the concentration, source, antagonism, and health risks of Se and TMs in fish. In this study, 120 fish samples (14 species), 24 sediment samples, and 24 water samples were collected to investigate the antagonistic effects, sources, and health risks of TMs and Se in fish from a typical selenium-rich and high cadmium region. Zn and Se in fish from the Gongxin River were higher than in the background, which might be attributed to the different feeding habits of different fish species. The apparent antagonism between Se and Cu, Pb, and Cd was explored, and the results showed that 30%, 75%, and 100% of the Se/Cu, Se/Pb, and Se/Cd ratios were greater than one, indicating that Cu, Pb, and Cd in fish might be combined with or detoxicated by Se. The source analysis of the elements showed that the geological background was the source of TMs and Se in fish samples. The amounts of Se and TMs were all within China's acceptable level guidelines, signifying no harm to citizens from eating fish.

Comparison of Essential and Toxic Metals Levels in some Herbal Teas: a Systematic Review

In the present study, we reviewed the literature as a systematic review to investigate the concentration of some metals (essential, none essential, and toxic metals) in herbal teas and their health risks. The search extended the literature from the database, including Google Scholar, PubMed, and Scopus, using the terms "herbal teas" combined with "heavy metals, essential metals, thyme, rosemary, chamomile, and tea" also with "iron, zinc, aluminum, chromium, cobalt, nickel, manganese, arsenic, cadmium, and lead" in titles and abstracts. The search was limited to articles published from 2012 to 2023 years. Initially, 212 articles were found; by detailed consideration, only 49 papers fit the inclusion criteria and were selected for further study. The mean of metal concentration, standard deviation, data distribution, and sample size were applied to generate data from the articles. The results indicated that all commonly consumed herbal teas included metals. None of them meet the requirements of the WHO requirements. However, more than 70% of their health risks are acceptable. The risks of arsenic and lead in tea and cadmium in black tea were considerably higher than in others. According to the review results, it is important to prevent heavy metal contamination of herbal teas by modifying cultivation patterns and also to prevent to consumption of low-quality herbal teas.

Effect of exposures to multiple metals on blood pressure and hypertension in the elderly: a community-based study

A chronic disease, hypertension (HTN) is prevalent among the elderly. Exploring the factors that influence HTN and blood pressure (BP) changes is of great public health significance. However, mixed exposure to multiple serum metals has had less research on the effects on BP and HTN for the elderly. From April to August 2019, 2372 people participated in the community physical examination program for the elderly in Tongling City, Anhui Province. We measured BP and serum levels of 10 metals and collected basic demographic information. We analyzed the relationship between metal levels and changes in BP and HTN by the least absolute shrinkage and selection operator regression, Bayesian kernel machine regression model, and generalized linear model. In multiple models, lead (Pb) and cadmium (Cd) were still significantly associated with HTN occurrence after adjusting for potential confounders (Pb: ORquartile 4 VS quartile 1 = 1.20, 95% CI 1.01-1.43; Cd: ORquartile 4 VS quartile 1 = 1.37, 95% CI 1.16-1.62). In the male subgroup, results were similar to those of the general population. In the female group, Cd was positively correlated with HTN and systolic blood pressure, while Pb was not. According to this study, Pb and Cd were correlated with BP and HTN positively, and there was a certain joint effect. To some extent, our findings provide clues for the prevention of hypertension in the elderly.

Hepato-renal toxicity of low dose metal(oid)s mixture in real-life risk simulation in rats: Effects on Nrf2/HO-1 signalling and redox status

The understanding that humans are exposed to a low level of toxic metals and metalloids in their lifetime has resulted in a shift in scientific and regulatory perspectives from the traditional evaluation of single metal toxicity to complex mixtures, relevant to real-life exposure. Therefore, the aim of this study was to examine the impact of real-life, 90-days exposure to mixture of toxic metal(oid)s, Cd, Pb, Ni, Cr, As and Hg, on the nuclear factor erythroid 2-related factor 2 and hemoxygenase-1 (Nrf2/HO-1) signalling and redox status by assessing total sulfhydryl groups (SH), glutathione (GSH), superoxide dismutase activity (SOD), malondialdehyde (MDA), and ischemia modified albumin (IMA) in the liver and kidney of Wistar rats. Animals (20 males and 20 females) were randomized in 2 control and 6 treated groups that received by oral gavage mixture of metal(oid)s solutions in doses that reflect blood metal(oid) levels determined in previous human biomonitoring study as benchmark dose (F/M _BMD), median (F/M _MED), and 95th percentile (F/M _95). Our results have shown that metal(oid)s mixture impaired the activation of the Nrf2/HO-1 pathway in the kidney and liver of male rats and kidney of female rats, followed by depletion of GSH levels in males. Additionally, in males elevated levels of IMA in the liver were observed, while in both genders increased MDA levels were observed in the kidney. Interestingly, the effects were more pronounced in male than in female rats. This study is among the first that examined hepato-renal toxic mechanisms of real-life metal mixture exposure, while our results might be of immense importance for assessing the risk of exposure to mixtures of toxic substances.

Removal of toxic metals using iron sulfide particles: A brief overview of modifications and mechanisms

Growing mechanization has released higher concentrations of toxic metals in water and sediment, which is a critical concern for the environment and human health. Recent studies show that naturally occurring and synthetic iron sulfide particles are efficient at removing these hazardous pollutants. This review seeks to provide a concise summary of the evolution in the production of iron sulfide particles, specifically nanoparticles, through the years. This review presents an outline of the synthesis process for the most dominant forms of iron sulfide: mackinawite (FeS), pyrite (FeS2), pyrrhotite (Fe1-x S), and greigite (Fe3S4). The review confirms that both natural forms of iron sulfide and modified forms of iron sulfide are highly effective at removing different heavy metals and metalloids from water. Concurrently, this review reveals the interaction mechanism between toxic metals and iron sulfide, along with the impact of conditions for remedy and rectification. None the less, modifications and future investigations into the synthesis of novel iron sulfides, their use to adsorb diverse environmental pollutants, and their fate after injection into polluted aquifers, remain crucial to maximizing pollution control.

Tracing the footprints of Arctic pollution: Spatial variations in toxic and essential elements in Svalbard reindeer (Rangifer tarandus platyrhynchus) faeces

The Arctic is an accumulation zone of long-range transported pollution. In addition, local anthropogenic activities further contribute to regional pollution levels. The Svalbard reindeer (Rangifer tarandus platyrhynchus) is a suitable organism for studying and monitoring exposure to anthropogenic pollutants at the base of the terrestrial Arctic food web, and reindeer faeces have been promoted as non-invasive means of biomonitoring contaminant exposure. This study used HR-ICP-MS to analyse levels and composition of 16 elements in Svalbard reindeer faeces (n = 96) and soil (n = 9) from two locations on Svalbard, with the aim to assess whether local anthropogenic pollution influences element bioavailability. One of the sampling areas, the Nordenskiöld coast, is situated on the west coast of Spitsbergen, close to the Arctic Ocean and relatively far from local anthropogenic sources. The other sampling area, Adventdalen, is located further inland and close to Longyearbyen, the largest settlement of the archipelago. There was a significant difference in faecal elemental concentration and composition between the Adventdalen and Nordenskiöld coast reindeer populations. Elements of geogenic origin (e.g., Al, Cu and Fe) were found at higher levels in faeces from Adventdalen. In comparison, levels of Ca, Se and the toxic elements Cd and Pb were higher in faecal samples from the Nordenskiöld coast. The significantly higher levels of faecal Cd and Pb at Nordenskiöld coast may be due to marine input, dietary differences between the populations, or possible anthropogenic influence from the nearby settlement of Barentsburg. There was, however, a decoupling in elemental composition between faecal and soil samples, which may derive from a selective vegetational uptake of elements from the soil. The results suggest that reindeer are exposed to a range of elements and that faeces can be used to monitor the exposure to bioavailable environmental levels of both essential and toxic elements in terrestrial ecosystems.

Assessment of some toxic elements (Co, Cr, Mn, Se, and As) in muscle, offal, hair, and blood of camels (Camelus dromedaries) and their risk assessment

Background

Camel meat tainted with heavy metals or trace elements may pose a health risk to consumers. Heavy metal contamination poses a severe danger due to both their toxicity and bioaccumulation in the food chain.

Aim

To estimate the residual levels of heavy metals (Co, Cr, Mn, Se, and As) in muscle, liver, kidney, hair, and serum of three camel breeds (Magaheem, Maghateer, and Wadha) collected from Al-Omran abattoir, Al-Ahsa, Saudi Arabia.

Methods

A total of 225 tissue samples (muscles, liver, kidney, serum, and hair) were taken and analyzed using an Atomic Absorption Spectrophotometer. Health risk assessment was assessed using the guidelines set by the US Environmental Protection Agency.

Results

Camel breed significantly (p < 0.05) influences Co, Cr, Mn, and Se accumulation and distribution in organs and muscle; however, arsenic accumulation was not significantly affected (p < 0.05) by camel breeds. The highest values of Co, Cr, Se, and Mn in all examined samples were detected in the liver samples of Maghateer and Magaheem breeds. Furthermore, significant strong positive correlation between serum and liver cobalt, chromium, manganese, and arsenic. The estimated daily intake owing to camel meat consumption was less than the tolerated daily intake.

Conclusion

Heavy metals were distributed among different breeds of camel. Trace elements (Pb and Cd) in meat and offal were below the international maximum permissible limit. The correlation between samples reflects the role of hair as a good tool for the identification of heavy metal pollution.

Dilute-and-shoot ICPMS quantification of V, Ni, Co, Cu, Zn, As, Se, Ag, Cd, Ba, and Pb in fruit juices based on matrix overcompensation calibration

Analysis of V, Co, Ni, Cu, Zn, As, Se, Ag, Cd, Ba, and Pb in fruit juices was performed by inductively coupled plasma mass spectrometry (ICPMS) after simple 50-fold dilution in 1% (v/v) HNO3-0.5% (v/v) HCl-5% (v/v) ethanol. Ethanol was added to overwhelm native organic components and dominate matrix effects. A universal calibration curve was built based on a likewise treated reagent standard series. This new matrix overcompensation calibration (MOC) strategy was developed to effectively compensated for matrix effects of carbon origin and achieved quantitative (92.5-118.8%) recoveries comparable to those by standard addition calibration (92.1-117.8%) and microwave-aided digestion (99.3-116.8%). The LODs were 0.528, 0.204, 0.195, and 2.07 ng mL-1 for toxic elements As, Cd, Pb, and Ni, respectively, adequate for their regulatory monitoring. Ge, Rh, Tb, and Ir were used as internal standards. MOC renders a calibration curve universally applicable to any clear fruit juices of diversified crop, geographic, and manufacturer origins resulting in cost saving and enhanced productivity.

Risk assessment of some toxic metals in canned fish products retailed in Mansoura, Egypt

Background

Canned fish products are widely consumed in Egypt, particularly for protein-rich meals that are quick to prepare and low in calories. Canned fish products are contaminated with toxic metals from the fish itself or from canning materials during processing.

Aim

To determine the residual levels of cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg), aluminum (Al), and Tin (Sn) in some canned fish products obtained from retail shops in Mansoura, Egypt. Furthermore, noncarcinogenic health risks evaluation for the Egyptian population due to hazardous metal oral intake.

Methods

One hundred canned fish products (20 each of herring, mackerel, salmon, sardine, and tuna) were collected from May to September 2023, and canned fish products were obtained from Mansoura city markets in Egypt. Samples were digested in a solution composed of 60% nitric acid and 40% perchloric acid, and then an atomic absorption spectrophotometer was used for the detection of selected toxic metals.

Results

It was found that the residual level of hazardous metals exceeded the acceptability level established in the European Union for Pb, Cd, and Hg by 20%, 10%, and 10%, 15%, 5%, and 20%, 35%, 30%, and 45%, 25%, 25%, and 40%, in examined herring, mackerel, sardine, and tuna, respectively. In contrast, all salmon samples were accepted for Pb and Hg, and only 5% were not accepted due to a higher Cd level than the maximum permissible limit. The average estimated daily intake of (EDI) is below the tolerable daily intakes (TDIs) for all metals. Comparatively, the EDI of Hg was 0.265 µg/kg body weight (B.W) exceeded TDIs 0.228 µg/kg B.W. The hazard index for canned tuna and sardines is more than one.

Conclusion

Canned fish products are contaminated with a variety of toxic metals, especially sardine and tuna. Therefore, it is advised to decrease the consumption rate of such fish products.

The impact of toxic metal bioaccumulation on colorectal cancer: Unravelling the unexplored connection

Colorectal cancer is a major public health concern, with increasing incidence and mortality rates worldwide. Environmental factors, including exposure to toxic metals, such as lead, chromium, cadmium, aluminium, copper, arsenic and mercury, have been suggested to play a significant role in the development and progression of this neoplasia. In particular, the bioaccumulation of toxic metals can play a significant role in colorectal cancer by regulating biological phenomenon associated to both cancer occurrence and progression, such as cell death and proliferation. Also, frequently these metals can induce DNA mutations in well-known oncogenes. This review provides a critical analysis of the current evidence, highlighting the need for further research to fully grasp the complex interplay between toxic metal bioaccumulation and colorectal cancer. Understanding the contribution of toxic metals to colorectal cancer occurrence and progression is essential for the development of targeted preventive strategies and social interventions, with the ultimate goal of reducing the burden of this disease.

The good, the bad, and the ugly of metals as antimicrobials

We are now moving into the antimicrobial resistance (AMR) era where more antibiotic resistant bacteria are now the majority, a problem brought on by both misuse and over use of antibiotics. Unfortunately, the antibiotic development pipeline dwindled away over the past decades as they are not very profitable compounds for companies to develop. Regardless researchers over the past decade have made strides to explore alternative options and out of this we see revisiting historical infection control agents such as toxic metals. From this we now see a field of research exploring the efficacy of metal ions and metal complexes as antimicrobials. Such antimicrobials are delivered in a variety of forms from metal salts, alloys, metal complexes, organometallic compounds, and metal based nanomaterials and gives us the broad term metalloantimicrobials. We now see many effective formulations applied for various applications using metals as antimicrobials that are effective against drug resistant strains. The purpose of the document here is to step aside and begin a conversation on the issues of use of such toxic metal compounds against microbes. This critical opinion mini-review in no way aims to be comprehensive. The goal here is to understand the benefits of metalloantimicrobials, but also to consider strongly the disadvantages of using metals, and what are the potential consequences of misuse and overuse. We need to be conscious of the issues, to see the entire system and affect through a OneHealth vision.

Assessment of toxic trace elements (Cd, Pb, As, and Co) in small, medium, and large individuals of Mytilus galloprovincialis and Perna perna mussel species along the Algerian coast

This research paper focused on the monitoring of marine sites using mussels, which are highly valuable organisms in assessing environmental health. However, a significant challenge arises when determining the appropriate size of mussels for monitoring purposes. The objective of this study was to examine the levels of Cd, Pb, As, and Co in three different size classes of two mussel species, Mytilus galloprovincialis and Perna perna, collected from three sites along the Algerian coast, each exhibiting varying degrees of pollution.At each of the study sites, a total of thirty individuals from small, medium, and large size classes of mussels were collected during four different time periods. The mussels were then dissected, and the concentrations of Cd, Pb, As, and Co were measured in the entire flesh of the mussels using ICP-MS.Across the various study sites, the concentrations of cadmium, lead, arsenic, and cobalt ranged from 0.06 to 1.32 mg/kg, 0.09 to 12.56 mg/kg, 4.23 to 18.31 mg/kg, and 0.11 to 1.85 mg/kg, respectively. Interestingly, the distribution of these metals in the three different size classes of mussels followed a consistent pattern at all the study sites. Large mussels exhibited higher concentrations, while small and medium-sized mussels displayed lower levels. These findings highlight substantial spatial and temporal variations in metal concentrations within the studied sites.

Utilizing mollusk soft tissue and shells as biomarkers for monitoring heavy metal pollution in mangrove forests

The primary objective of the study was to examine the distribution of various elements, namely Cadmium (Cd), Copper (Cu), Iron (Fe), Nickel (Ni), and Lead (Pb), in the soft tissues, shells, and associated surface sediments of Cerithidea obtusa (C. obtusa) mangrove snails collected from Sungai Besar Sepang. To conduct the analysis, the preferred and most convenient methods employed were Instrumental Neutron Activation Analysis (INAA) and Atomic absorption spectrometry (AAS). The results showed that the mean concentration of elements in the sediments and soft tissues followed the order Fe > Cu > Ni > Pb > Cd, while for the shell of C. obtusa, it was Fe > Ni > Cu > Pb > Cd.•Iron (Fe) showed the highest concentration among all elements monitored in sediments, soft tissues, and shells of C. obtusa.•The PF results indicated higher incorporation of Pb and Ni into shells.•BSAF results showed that C. obtusa shells accumulated more Cu and Cd from sediments, making them effective biomonitors.

Heavy metal contamination and health risk assessment of horticultural crops in two sub-cities of Addis Ababa, Ethiopia

This particular study was aimed to establish the level of heavy metals in different horticultural crops cultivated by irrigation and the soil in two sub-cities of Addis Ababa, Ethiopia, and quantitatively assess the health treat they pose for the consumer. A total of 151 vegetable samples comprised of lettuce (Lactuca sativa), cabbage (Brassica oleracea var. capitate), cucumber (Cucumis sativus), potato (Solanum tuberosum), parsley (Petroselinum crispum), Swiss chard (Beta vulgaris subsp. vulgaris), beetroot (Beta vulgaris), green onion (Allium porrum L.) and 28 soil samples were collected for this study. Six toxic elements were analyzed using microwave plasma atomic emission spectroscopy (MP-AES) after microwave assisted digestion of the samples. The concentrations of examined trace elements in vegetables (mg/kg) were found in the range of 5.50-93.00 for zinc; below detection limit (BDL)- 18.50 for copper; BDL-2.50 for nickel; BDL-17.00 for lead; 5.00-4256.50 for manganese and 22.00-8708.00 for iron. Considering the mean Pb content values, all vegetables exceeded the maximum permissible level set by the joint FAO/WHO commission in both irrigation sites. In case of Mn parsley, swiss chard, and green onion all from site two exceeded the maximum allowable values. With the exception of potato from irrigation site one, all vegetables exceeded the maximum permissible limit set for Fe concentration and out of which parsley, swiss chard, and green onion, all from site two, exceeded by more than double amount. The same trend is observed for the concentration of Mn and Fe in the soil samples. In fact, in both irrigation sites their concentration exceeded the allowable limits set by United Nation Environment Program (UNEP) for agricultural soils. The metal pollution load index revealed that in most of the vegetables studied the overall pollution load of trace metals were higher in Kolfe Keranyo irrigation site. The risk assessment study using indices like estimation of daily/weekly dietary exposure, hazard quotient and metal pollution load index all suggested consumption of the studied vegetables poses a significant health risk for the consumer. For adults the calculated target hazard quotient for the trace element Pb is higher than 1 (one) for all of studied vegetables ranging from 11.086 (cucumber) to 17.881 (beetroot) with a 98.216% and 98.464% contribution to the hazard indices, respectively. For a child consumer, Mn showed a higher target hazard quotient vales ranged from 0.0107 (cucumber) to 0.0495 (green onion) with a 70.86% and 88.85% contribution to the total hazard indices, respectively. The soil pollution indices also indicated that the degree of metal enrichment in soils and sediments are higher than the allowable limits. Therefore, a prompt action is required to curb the problem and ensure the public safety along the food system line.

Prenatal exposure to metal mixtures and lung function in children from the New Hampshire birth cohort study

Prenatal exposure to metals/metalloids, even at common US population levels, may pose risks to fetal health, and affect children's lung function. Yet, the combined effects of simultaneous prenatal exposures on children's lung function remain largely unexplored. This study analyzed 11 metals (As speciation, Cd, Co, Cu, Mo, Ni, Pb, Sb, Se, Sn, Zn) in maternal urine during weeks 24-28 of gestation and evaluated lung function, including forced vital capacity (FVC) and forced expiratory volume in the first second of expiration (FEV1), in 316 US mother-child pairs at around age 7. We used Bayesian Kernel Machine Regression (BKMR), weighted quantile sum regression (WQSR), and multiple linear regression to examine the association between metal mixture exposure and children's lung function, adjusting for maternal smoking, child age, sex, and height. In BKMR models assessing combined exposure effects, limited evidence of metal non-linearity or interactions was found. Nevertheless, Co, As species, and Pb showed a negative association, while Mo exhibited a positive association with children's FVC and FEV1, with other metals held constant at their medians. The weighted index, from WQSR analysis assessing the cumulative impact of all metals, highlighted prenatal Mo with the highest positive weight, and Co, As, and Sb with the most substantial negative weights on children's FVC and FEV1. Urinary Co and Pb were negatively associated with FVC (β = -0.09, 95% confidence interval (CI) (-0.18; -0.01) and β = -0.07, 95% CI (-0.13; 0.00), respectively). Co was also negatively associated with FEV1 (β = -0.09, 95% CI (-0.18; 0.00). There was a negative association between As and FVC, and a positive association between Mo and both FVC and FEV1, though with wide confidence intervals. Our findings suggest that prenatal trace element exposures may impact children's lung function, emphasizing the importance of reducing toxic exposures and maintaining adequate nutrient levels.

Association Between Multiple Metal(loid)s Exposure and Blood Lipid Levels: Evidence from a Cross-Sectional Study of Southeastern China

Exposure to essential and toxic metals occurs simultaneously as a mixture in real-life. However, there is no consensus regarding the effects of co-exposure to multiple metal(loid)s (designated hereafter metals) on blood lipid levels. Thus, blood concentrations of six human essential metals and five toxic metals in 720 general populations from southeastern China were simultaneously determined as a measure of exposure. In addition, quantile g-computation, Bayesian kernel machine regression, elastic net regression, and generalized linear model were used to investigate both the joint and individual effects of exposure to this metal mixture on human blood lipid levels. The significant positive joint effect of exposure to this metal mixture on serum total cholesterol (TC) levels, rather than on serum triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol, Castelli risk index I, Castelli risk index II, atherogenic coefficient, and non-HDL-C levels, was found. In addition, the positive effect may be primarily driven by selenium (Se), lead (Pb), and mercury (Hg) exposure. In addition, on the effect of TC levels, the synergistic effect between Pb and Hg and the antagonistic effect between Se and Pb were identified. Our finding suggests that combined exposure to this metal mixture may affect human blood lipid levels. Therefore, reducing exposure to heavy metals, such as Pb and Hg, should be a priority for the general population. In addition, Se supplementation should also be considered with caution.

Exploration of Toxic and Essential Metals in Popular Rice Grains of Bangladesh and Associated Human Health Risk Implications

In order to evaluate the benefits as well as the impacts of essential and toxic metals regarding human health, the six common rice grains (katarivhog, bashful, banglamoti, najirshail, branded miniket and loose miniket) were collected from four wholesale markets in Dhaka, the capital of Bangladesh, and were analyzed with different atomic absorption spectroscopy (AAS) techniques. The mean concentrations of the toxic metals Pb, Cd, Cr, and As had 0.299 ± 0.017, 0.157 ± 0.012, 1.33 ± 0.084, and 0.120 ± 0.006 mg/kg, respectively, while those of the essential metals Fe, Cu, Zn, Na, Ca, and Mg had 7.90 ± 0.447, 3.11 ± 0.097, 10.6 ± 0.340, 37.4 ± 0.622, 90.1 ± 7.70, and 115.8 ± 1.61 mg/kg, respectively. Among them, the mean concentrations of toxic metals (Pb, Cd, Cr, and As) exceeded the maximum allowable concentration in rice set by the Codex Alimentarius Commission (CAC). Risk assessment of the heavy metals Pb, Cd, Cr, As, Fe, Cu, and Zn showed that their estimated daily intakes were below the daily reference doses for adults. However, Cd and Cr individually were found to have the target hazard quotient value close to 1 (threshold limit), indicating that they alone are capable of potential health hazards from continuous rice consumption, while the hazard index has surpassed three units signifying greater danger associated with the current trend of consumption. A very high chance of developing cancer in the near future is predicted by incremental lifetime carcinogenic risk (ILCR) analysis for continued intake of Cr (ILCR > 1E-03), and a moderate to high risk is predicted for other carcinogenic substances (Pb, Cd, and As) (ILCR in between 1E-03 and 1E-05) with present rice consumption. The contribution of the essential metals to the RNI revealed that Cu from rice contributes more than 100% in most samples, and the overall contribution is in the following order: Cu > Zn > Fe > Mg > Ca > Na. To ensure the safety of staple foods for human health, it ought to be necessary to design a plan to measure the budget of hazardous metals from all sources with proper surveillance by relevant authorities.

Assessment of health risks due to toxic metals in demersal fish captured from Saros and Edremit Bays, Northern Aegean Sea

Bays are vulnerable ecosystems generally located near densely populated areas where toxic metals tend to accumulate and stay longer, affecting marine life. This study aimed to investigate the age-based health risks arising from Hg, Cd, Pb, and As in demersal fish captured from two major bays in the Aegean Sea. For this purpose, red mullet, whiting, piper gurnard, and tub gurnard, frequently consumed species, were caught from Saros and Edremit Bays. Toxic metal concentrations were determined from the muscle tissue of fish. Health risk assessments were conducted by the estimation of weekly intake (EWI), provisional tolerable weekly intake (PTWI), target hazard quotient (THQ), total THQ (TTHQ), and target carcinogenic risk (TR). Red mullet from Edremit Bay was the species with the highest toxic metal levels, which were 1.597 mg/kg, 0.041 mg/kg, 0.070 mg/kg, and 19.351 mg/kg for Hg, Cd, Pb, and As, respectively. Whiting from Edremit Bay had higher mean concentrations of Hg and As than those from Saros Bay. The levels of Hg, Pb, and As (0.328, 0.043, and 0.574 mg/kg) in the tub gurnard were higher in comparison with the piper gurnard (0.252, 0.020, and 0.382 mg/kg) caught in the same station in Saros. TTHQs of red mullet and whiting from the same bay were found to be > 1, indicating potential health risks for all nine age categories studied. On the other hand, TTHQs of all species from Saros Bay were determined to be > 1 for the first four age categories, which might trigger health risks for children and adolescents. According to the TR index for Pb, no risk was determined for the fish from both bays. However, TR calculations for inorganic As indicated high cancer risk in most of the age categories for red mullet and whiting from Edremit Bay. To sum up, the results revealed that the fish captured from Edremit Bay posed serious health risks in terms of Hg and As concentrations for all nine age categories. Surveillance and monitoring of toxic metal levels in demersal fish and population-based health risk evaluation are vital in heavily populated bays.

Assessment of human health risks of toxic elements in coastal area between Al-Khafji and Al-Jubail, Saudi Arabia

The present work aims to document the distribution of toxic elements (TEs) and assess the human health risk posed by the TEs in the marine sediment of the Arabian Gulf, Saudi Arabia. The descending order of TE averages (μg/g) was as follows: Ni > Cr > V > Zn > Pb > Cu > As > Co. Based on the enrichment factor values, only minor enrichment for Pb, As, Cr, and Ni was noted. The hazard index (HI) values for the non-carcinogenic risk of the TEs were less than 1.0, and the lifetime cancer risk values for carcinogenic Pb, Cr, and As ranged between 2.96 × 10-8 and 5.44 × 10-5, indicating no significant health hazards for the inhabitants of the study area.

Evaluating trace elements in urban forest soils across three contrasting New England USA towns and cities by pXRF and mass spectrometry

Urban forest soils perform important ecosystem services, such as the sequestration of potentially toxic elements, but some can serve as a source for human exposure if ingested or eroded by wind. Assessment of trace elements in urban soils through traditional methods is costly but portable X-ray fluorescence (pXRF) can allow for rapid screening for hazardous concentrations. Our objectives were (1) evaluate trace elements (As, Cd, Cr, Cu, Pb, and Zn) at 460 locations in and around urban forests across three town and cities in New England and across multiple land-uses, (2) evaluate accuracy and precision of pXRF compared with traditional digestion-inductively coupled plasma analyses, (3) determine if pXRF measurements are improved by processing the soil (oven drying, rock fragment removal, and organic matter (OM) removal). Our findings show that urban forest soils have extensive Pb accumulations (42 out of 460 with >200 mg/kg), while As and Zn exceeded regulatory limits in limited outlier samples. Urban forest soils adjacent to multi-family residences have higher Pb and Zn concentrations than recreational and open lots. Fortunately, Cd, Cr, and Cu were far below hazardous concentrations. Our comparisons suggest pXRF measurements of Cu, Pb, and Zn can be considered accurate while Cd and Cr may be screened by pXRF. However, As should not be considered qualitative nor quantitative due to 70% type 1 (false positive) error on samples. While the accuracy and precision were nominally improved through soil drying, removal of rock fragments, and removal of OM (<5% decrease in relative error), our results show processing soil samples is likely not needed.

An analysis of the foremost issues with artisanal and small-scale gold mining from Ghana's perspective

Ghana has abundant mineral reserves in many of its regions, and gold mining remains one of the country's main sources of revenue. Given Ghana's current position in the global gold market, this review provides insight into the ASGM sector to give an understanding of the pertinent issues in the sector and its role in the socio-economic development of the country. This review assesses the effects of ASGM operations in economic, social, health, and environmental contexts to raise awareness of issues related to ASGM. It evaluates the measures taken to lessen the consequences of ASGM and maintain the sector's long-term viability. This review considers the foremost issues, including continued Hg use in ASGM, recent use of cyanide in ASGM, pollution of water bodies, and toxic metal contamination. It takes into account sustainable measures and remedial techniques that Ghana has implemented to alleviate the negative effects and support best mining practices. The primary factors influencing people to participate in ASGM are the need for quick sources of income, the scarcity of jobs in rural areas, the economic hardship, the need to supplement earnings from other activities like trading, and the comparatively meager profits from agricultural activities. Findings indicated that to gain more traction in addressing the challenges in the ASGM sector, the involvement of the community and direct stakeholders is essential to promoting responsible mining and environmentally sustainable practices. This review will increase awareness and pressure on decision-makers, researchers, and ASGM communities about the relevance of environmental conservation and sustainability.

Impact of domestic and industrial effluent on marine environment at Karachi Port Trust (KPT) coastal area, Pakistan

The extent of aquatic pollution of Karachi Port Trust (KPT) coastal area located at the south of Pakistan coast has increased considerably in the last few decades due to unrestricted discharge of sanitary waste. The current study lays emphasis on the identification of vulnerable zones severely impacted by pollution in the KPT coastal area using laboratory monitoring, geospatial techniques, and statistical analysis. During 2019, sampling was conducted along the KPT coastal area, and 54 samples of seawater were collected during pre- and post-monsoon seasons. The outcomes of physical and chemical analysis revealed that the concentrations of BOD (biochemical oxygen demand), COD (chemical oxygen demand), nitrate, phosphate, phenol, cyanide, and oil and grease frequently exceeded the permitted limit of international norms and reached much greater levels. The levels of perilous metals in the seawater samples were in the order Ni>Cr>Cu>Pb>Cd>As in both phases and also reached to elevated levels as a consequence of the indiscriminate discharge of untreated industrial and domestic wastewater. Based on detailed examination during pre- and post-monsoon, six sites near KPT, Lyari River outfall, and Karachi Harbour were identified as highly polluted zones due to heavy discharge of sanitary effluents at these sites. In particular, the industrial zones present in the formal and informal sectors of Karachi are responsible for the deterioration of the KPT coastal area. Therefore, it is advised to design and build a submerged drainage system to transport and distribute massive amounts of treated municipal and industrial waste to the deep open sea in order to minimize the high pollutant levels in these locations.

Toxicological analysis of metals content in agro-food wastes as possible supplement in animal feed

The agro-food surplus is considered the most abundant renewable resource, interesting for the economic and environmental impact, with a possible employment in different productive fields such as supplement in animal feed. For a safe and effective enhancement of agro-food wastes it is needed a toxicological analysis before of their employment, to avoid potential risks to animals, humans and environment. The purpose of this study was to evaluate the metals content (Cu, Fe, Zn, Mg, Na, K, Ca, Mn, Se, Zn, Co, Ni, V, Sb, Mo, Cr and Pb, Cd, As, Ba), in agro-food wastes through ICP-MS analysis. The results obtained showed the presence of metals analysed with a significant content of essential micro and macro-elements; with regard to toxic metals, only strawberries and fennel samples showed Pb levels above the MRL. These data confirm, from the toxicological point of view, a possible and safe reuse of the most of all agro-food wastes, as raw material at low cost and rich of essential nutrients and particularly as supplement in animal feed.

Graphitic carbon nitride derived probes for the recognition of heavy metal pollutants of environmental concern in water bodies

Graphitic carbon nitride (g-CN) has a number of valuable features that have been recognized during the studies related to its photocatalytic activity enhancement derived by visible light. Because of these characteristics, g-CN can be used as a detecting signal transducer with different transmission modalities. The latest up-to-date detection capabilities of modified g-CN nanoarchitectures are covered in this study. The structural features and synthetic methodologies have been discussed in a number of reports. Herein, employment of the g-CN as a promising probing modality for the recognition of different toxic heavy metals is the promising feature of the present study.

Assessment of toxic metal pollution in Yueqing Bay and the extent of metal-induced oxidative stress in Tegillarca granosa raised in this water

Yueqing Bay is an important economic shellfish culture zone in Zhejiang Province, China. However, increased pollution in the water caused by toxic metals has led to the bioaccumulation of toxic metals in cockles such as Tegillarca granosa, and the consequence of toxic metal-associated toxicity in these animals. This study aimed to assess the concentration of toxic metals in the water and sediment in four different sites (Baisha, Qingjiang, Nanyue, and Wengyang) within Yueqing Bay and to evaluate the extent of metal bioaccumulation in T. granosa raised in the aquaculture farms located within the four sites, as well as the changes in biomarkers in T. granosa in response to the metals. The assessment was carried out at two different times of the year, January and July. The water and sediment samples taken from the aquaculture farms in Baisha (S1), Qingjiang (S2) and Nanyue (S3) were found to have a comprehensive toxic metal pollution index (Pc) <1, indicating that these farms were not polluted. However, the water and sediment samples taken from the aquaculture farm in Wengyang (S4) had a Pc between 1 and 2, indicating mild toxic metal pollution. The edible risk assessments (HQ) of T. granosa in all four farms were <1, and therefore, these cockles could be considered safe for human consumption. The toxic metal enrichment in T. granosa exhibited a strong correlation with the toxic metal content in the sediment. In all four farms, CAT and SOD activity levels in the visceral mass of T. granosa were higher than those found in the foot, and a significantly higher level of CAT activity was detected in July compared with January. Similarly, MDA and H2O2 contents in the visceral mass were also higher in July than in January. Tegillarca granosa individuals taken from S4 and S3 farms exhibited significantly higher levels of metallothionein (MT) mRNA and MDA compared with individuals from S1 and S2 farms. Furthermore, the levels of MDA and MT mRNA showed significant positive correlations with Cd, Cr, Hg, and Cu. Elevation of lipid peroxidation in these cockles coincided with increasing levels of endogenous antioxidants. The visceral mass of T. granosa and its MDA level could be used as a tissue indicator and a biochemical marker, respectively, for detecting toxic metal pollution. MT mRNA might also be used as a molecular marker of toxic metal pollution. The integrated biomarker response version 2 (IBRv2) values of the four aquaculture farms in Yueqing Bay showed the order S4 > S3 > S2 > S1, indicating that S4 had the most serious metal-induced stress. Furthermore, the IBRv2 values correlated with the Nemerow composite index (Pc) for all the cockles examined. Thus, as far as the contamination of aquaculture farms in Yueqing Bay by toxic metals is concerned, the aquaculture farm in Wengyang (S4) was mildly contaminated by toxic metals. However, the contamination was relatively low, presenting a low risk for the local population of T. granosa.

Using benthic macroinvertebrates as bioindicators to evaluate the impact of anthropogenic stressors on water quality and sediment properties of a West African lagoon

This study aimed to investigate the impact of anthropogenic stressors (landfilling, navigation for transport of goods, cooling in fossil fuel, urbanization, industrial expansion, agriculture activities, and recreational activities) on environmental variables, microbiological quality, and sediment properties using benthic macroinvertebrates as a bioindicator within Lagos Lagoon, Nigeria. Four (4) sampling stations were established with respect to their importance/anthropogenic activities within the Lagos Lagoon. Surface water, bottom substrates, and benthic macroinvertebrate fauna samples were collected bimonthly from each sampling station for a year and analyzed using appropriate standard methods and procedures. The highest pH range of 7.96-8.01 (7.98 ± 2.35) was recorded at Site IV, while the lowest range of 6.41-7.01 (6.15 ± 1.14) was observed at Site II, and there was a significant difference (p < 0.05) among the pH mean values across the sites. High values of salinity, chloride, sodium, COD, BOD, manganese, nickel, cadmium, and nitrate were recorded among the surface water physicochemical parameters, which were above WHO (2011) permissible limits, while the high concentrations of toxic metals (Pb, Cr, Zn, and Cd) was recorded in sediment. A total of 26 species of benthic macroinvertebrates were recorded during this study, which belongs to eight (8) classes. Gastropoda recorded the highest percentage contribution of 39.12%, followed by polychaeta accounting for 30.34%, while malacostraca contributed 2.63%. The highest abundance of macroinvertebrates was recorded at Site I (256 Indiv/m2), followed by Site IV (252 Indiv/m2), and the least was observed at Site II (195 Indiv/m2). Based on the results of the physico-chemical, heavy metals, microbial quality, and macroinvertebrates assemblage obtained from this study revealed the adverse effect of anthropogenic activities on water quality degradation. It plays a significant role in the distribution and diversity of benthic macroinvertebrates in an aquatic environment.