Search Results (3,799)

Heavy metal contamination in agricultural production is a significant public health issue in Mexico, as it directly impacts food safety and population exposure through dietary intake. Available scientific evidence indicates that vegetables and other plant-derived foods can serve as significant exposure pathways for toxic elements such as arsenic, cadmium, lead, chromium, and mercury. The consumption of contaminated foods may contribute to cumulative adverse health effects, including neurological, renal, and reproductive alterations, as well as an increased risk of chronic diseases. In Mexico, risk assessment is further constrained by methodological heterogeneity across studies and by difficulties in translating scientific evidence into concrete regulatory actions. Critically, the national regulatory framework lacks specific standards establishing maximum permissible limits for heavy metals in fresh fruits, vegetables, and grains, despite their central role in the population’s diet. Regulations focus primarily on drinking water quality and selected processed foods, creating a regulatory gap in the direct control of contaminants in crops. The findings underscore the urgent need to strengthen public policies by establishing crop-specific regulatory standards, implementing systematic monitoring programs, and integrating food safety considerations more effectively into environmental, agricultural, and public health policies in Mexico. Full article

Groundwater contamination by dissolved metals and metalloids in the Chiang Mai Basin is an important drinking-water concern, yet the coupled depth patterns, hydrogeochemical controls, composite contamination status, and screening-level health implications have not previously been assessed in an integrated basin-scale framework. This study evaluated 120 groundwater samples from alluvial wells classified by depth as shallow (≤30 m, n = 40), intermediate (31–60 m, n = 35), and deep (>60 m, n = 45). Samples were analyzed for nine dissolved metals and metalloids (Fe, Mn, As, Cd, Pb, Cr, Zn, Hg, and Se) together with pH, Eh, and total dissolved solids (TDS). The highest exceedance frequencies were observed for Fe (72.5% of samples, >0.3 mg/L acceptability threshold), Mn (65.0%, >0.08 mg/L), and As (45.8%, >10 μg/L). Fe and Mn increased significantly with depth, whereas As was enriched in deep wells but showed no statistically significant depth dependence. Pearson correlation and principal component analysis consistently identified a dominant redox-associated component in which Fe, Mn, and As covaried negatively with Eh, supporting redox-sensitive co-enrichment in deeper groundwater. Contamination factors calculated relative to selected global groundwater background values were >6 for all seven evaluated metals (Fe, Mn, As, Cd, Pb, Cr, and Zn), and the overall pollution load index (PLI) was 9.11, with the highest depth-specific PLI in deep wells (10.42). These indices are interpreted here as background-relative screening tools rather than stand-alone regulatory measures. A screening-level ingestion risk assessment identified arsenic as the dominant toxicological driver, with hazard quotients (HQ) of 1.97 for adults and 4.60 for children, and an estimated lifetime cancer risk (LCR) of 8.87 × 10^–4. The results support targeted monitoring of deeper wells, routine screening for As and Mn, and treatment strategies that can address the co-occurring Fe–Mn–As assemblage in alluvial groundwater. Full article

In this study, the carbothermic reduction of sodium antimonate in crucible smelting was investigated. The optimal process temperature was determined to be 900 °C, with 10% coke consumption (with an ash content up to 15.33%) and a feed particle size of minus 1 mm. The process does not involve the addition of slag-forming components. Sodium participates in the formation of the slag phase. According to the smelting results, the amount of antimony recovered as crude metal reached 71–72%, while the Sb content in the crude metal reached up to 94.5%. A significant portion of antimony (up to 27%) volatilizes with off-gases. A notable sodium content was detected in the crude antimony, reaching up to 8% in some samples, while more than 80% of sodium was transferred to the slag phase. Arsenic, present in the initial concentrate at a level of 0.6%, was distributed approximately equally among the metallic, slag, and gas phases. Lead was predominantly concentrated in the crude antimony. Iron preferentially dissolved in the crude antimony. Other impurities were distributed in comparable amounts between the metallic and slag phases. Tellurium, present in sodium antimonate at 0.79%, was detected in some samples within the slag phase. Full article

Increased soil metal concentrations may be detrimental to human health as well as the environment. This study was conducted to infer the potential environmental risks and possible sources of heavy metal pollution in serpentine soils in Alacakaya. For this purpose, the concentrations of Ni, Co, Zn, Pb, Cu, As, and Cr in 28 soil samples collected from serpentine soils in the region were determined using ICP-MS. The heavy metal pollution of soils in the region was examined by applying different indicators, and the pollution load index (PLI), contamination factor (CF) and geo-accumulation index (Igeo) were used to assess ecological risks. The average concentrations of metals were in the order of Ni (2003) > Cu (1220) > Cr (823) > Zn (206) > Co (159) > Pb (56.9) > As (38.9) mg kg⁻¹. The arsenic (As) concentration exceeded the limits permitted by the World Health Organization (WHO) in 53.6% of the soil samples, the zinc (Zn) concentration in 35.7%; the lead (Pb) concentration in 14.3%; and the Ni, Co, Cr, and Cu concentrations in 100% of the samples. The average Igeos were as follows: As 3.28 (heavily polluted); Cu, 3.23 (heavily polluted); Pb 1.04 (moderately polluted); Zn 0.71 (lightly polluted); Ni, 4.04 (heavily to extremely polluted); and Co 2.03 and Cr 2.35 (moderately to heavily polluted). According to Igeo values, it was stated that Ni, As, Cu, Cr and Co were the elements that posed the greatest ecological risk in the study area. According to the CF values, pollution is observed in all samples, and there is very serious Ni pollution. The heavy metals showing the most pollution were Cu > As > Cr > Co > Pb > Zn. Samples from the study area demonstrate strongly contaminated soil based on the PLI (mean 7.4) values. These findings provide important information for soil remediation and the removal of heavy metal contamination from soils in similar regions. Full article

Phosphogypsum (PG) stockpiles pose a persistent threat to regional water environments, yet their differential impacts on surface water and groundwater remain unclear. This study examined the pollution characteristics, sources, mechanisms, and model-predicted trends of PG-derived contaminants in both systems within a representative PG-affected region. Results showed that total phosphorus declined sharply from surface water to groundwater due to soil retention, whereas SO₄²⁻ and F⁻ remained comparable. Nitrogen species accumulated more in groundwater, indicating distinct transport and transformation processes. Arsenic was higher in surface water but rarely exceeded limits. In contrast, lead and manganese were significantly enriched in groundwater, exceeding standards by up to 27- and 11-fold, mainly due to reductive mobilization and subsurface geochemical processes. The Nemerow Index indicated heavy pollution in 35% of surface water and 43% of groundwater samples. Principal component analysis identified PG leachate as the dominant pollution source. Model predictions further suggested that increasing stockpile capacity would intensify contamination and pose long-term environmental risks. This study provided a scientific basis for understanding the distinct pollution mechanisms of PG stockpiles and offered guidance for targeted water environment management in PG-impacted areas. These findings have broader implications for regions globally facing similar challenges from industrial solid waste storage. Full article

Potentially toxic elements (PTEs) in mining-impacted wetlands can transfer from soil and water to forage and grazing livestock, resulting in dietary exposure for nearby communities. In this study, arsenic (As), lead (Pb), and cadmium (Cd) were quantified in key environmental matrices (soil, surface water, and forage) and in sheep tissues (liver, kidney, and muscle) from six georeferenced grazing sites in the Ite coastal wetland (Tacna, Peru) during the dry season. Samples were acid-digested following U.S. EPA protocols and analyzed by atomic absorption spectrometry (AAS) under QA/QC procedures (certified reference materials, blanks, duplicates, and matrix spikes); matrix-specific detection and quantification limits are reported. Arsenic dominated the contamination profile (forage: 428.6 mg kg⁻¹, dry weight; soil: 48.61 mg kg⁻¹; water: 0.97 mg L⁻¹) and was detected in sheep tissues (kidney: 0.1577 mg kg⁻¹; muscle: 0.1538 mg kg⁻¹; liver: 0.0644 mg kg⁻¹). Lead and cadmium were <LOQ in muscle and liver but were measurable in kidney (Pb: 0.0415 mg kg⁻¹; Cd: 0.0011 mg kg⁻¹). To support the interpretation of trophic transfer, screening transfer/bioaccumulation metrics (soil-to-forage, forage-to-tissue, and water-to-tissue) were calculated. Human dietary exposure was screened using estimated daily intake (EDI), hazard quotient (HQ), and margin of exposure (MOE). Because arsenic speciation was not measured, inorganic arsenic (iAs) risk was evaluated as a conservative upper bound (100% iAs) and through sensitivity scenarios (10–50% iAs). Under a high-meat-consumption scenario (300 g day⁻¹), the upper-bound assumption yielded HQ = 2.2 and MOE = 0.46; however, scenario analyses indicate that risk conclusions are highly dependent on the assumed iAs fraction. Overall, the results identify arsenic as a priority contaminant and support targeted grazing management, the provision of low-arsenic water sources, and remediation and monitoring actions to reduce exposure in vulnerable rural communities. Full article

Arsenic-contaminated groundwater is a major environmental concern, particularly in northern Argentina. Here, Microbacterium oxydans AE038-20, isolated from arsenic-rich groundwater, was investigated to elucidate its tolerance and transformation capacity. Growth assays showed that the strain tolerates inorganic arsenic [As(III), As(V)] and methylarsenite [MAs(III)] without significant inhibition. Speciation analyses revealed progressive oxidation of As(III) to As(V), reaching near-complete conversion after 10 days. Similarly, MAs(III) was fully oxidized to MAs(V). Genome sequencing identified ars-related determinants, including arsR, arsC, putative arsenite efflux systems, and arsP, supporting detoxification via arsenate reduction and arsenite efflux. Proteomic analyses confirmed the expression of proteins related to arsenic resistance, oxidative stress response, and metal transport. However, no canonical arsenite oxidases were detected at either the genomic or proteomic level. Despite this, M. oxydans AE038-20 exhibited clear arsenic oxidation activity. The detection of pigment-associated proteins and in vitro oxidation assays suggest an alternative mechanism potentially mediated by redox-active pigments. These findings highlight an alternative pathway for arsenic transformation in environmental bacteria. Full article

Heavy metal contamination of foods remains a persistent global challenge for food safety and public health, driven by industrialization, mining activities, intensive agriculture, and ongoing environmental degradation. This scoping review synthesizes peer-reviewed literature on the occurrence of priority toxic metals—arsenic, cadmium, lead, mercury, and nickel—in food matrices, with emphasis on contamination pathways, analytical detection strategies, and documented human health effects. The reviewed studies reveal widespread accumulation of heavy metals in staple foods, including cereals, vegetables, seafood, and processed products, with concentrations frequently approaching or exceeding international regulatory limits, particularly in regions exposed to strong anthropogenic pressure. Conventional laboratory-based techniques, such as atomic absorption spectrometry and inductively coupled plasma methods, remain the reference standards for quantitative determination and regulatory compliance; however, their application to large-scale or continuous monitoring is often constrained by cost, infrastructure, and operational complexity. Consequently, increasing attention has been directed toward emerging detection approaches, including portable X-Ray fluorescence, Raman/SERS spectroscopy, electrochemical biosensors, electronic tongues, and in situ magnetic measurements, as complementary tools for rapid screening and field-based surveillance. Among these, environmental magnetism and in situ magnetic techniques stand out as non-destructive, low-cost proxies capable of identifying metal-associated particulate contamination linked to food production systems. Chronic dietary exposure to heavy metals is consistently associated with neurotoxicity, nephrotoxicity, carcinogenicity, and oxidative stress, underscoring the need for integrated, multi-tiered monitoring frameworks to support early detection, risk assessment, and prevention. Full article

The rapid translocation of pesticide and metal residues in the environment and their entry into the food chain pose a significant risk to human health. Given the high global consumption of honey, quality control emphasizes the need for continuous monitoring and risk assessment. To evaluate contamination levels in honey from northern Croatia, a region with intensive agricultural land use, 38 comb honey and 22 extracted honey samples were collected by purposive one-time sampling in June 2023. These samples were analyzed for 190 pesticides using liquid chromatography–tandem mass spectrometry (LC-MS/MS) and gas chromatography–tandem mass spectrometry (GC-MS/MS), and for 17 trace metal(loid)s using inductively coupled plasma mass spectrometry (ICP-MS). The highest detection frequencies were observed for fipronil-sulfone, trifloxystrobin, and coumaphos in comb honey, and for N-(2,4-dimethylphenyl)-formamide (DMF) and N-(2,4-dimethylphenyl)-N′-methylformamidine (DPMF) in extracted honey. Glyphosate was the only pesticide to exceed the European Union (EU) maximum residue level (MRL) of 0.05 mg/kg in three honey samples. Elemental analysis quantified most target metals, with aluminum (Al), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn) being the most abundant, while silver (Ag), arsenic (As), and selenium (Se) were not detected in this study. None of the samples contained lead (Pb) above the regulatory limit for honey established in the EU (0.1 mg/kg). To ensure food safety, further efforts are required to assess the health risks associated with exposure to these contaminants through consumption of the evaluated food. Full article

This study revises the genus Cyanoboletus (Boletaceae) in the Mediterranean Basin, integrating single-locus and multi-locus phylogenetic analyses (ITS, LSU, tef1-α, and rpb2), morphological characterisation, ecology, and arsenic accumulation in basidiomes. Morphological descriptions (including a new form, Cyanoboletus mediterraneensis f. pallidus), comprehensive sampling, type studies, biogeography, macro- and microphotographs, an identification key, and a historical overview of the nomenclatural issues surrounding C. pulverulentus, C. poikilochromus, and C. mediterraneensis are given. An epitype collection is designated for C. pulverulentus. A new method to measure spore suprahilar depression has been proposed, which allowed more clear morphological separation between C. mediterraneensis and C. pulverulentus. This method may prove useful for species delimitation in other fungal groups that have asymmetric basidiospores. Additionally, we generated a new ITS sequence of the C. sinopulverulentus holotype and inferred its conspecificity with the later described C. flavocontextus. Furthermore, notes on the taxonomy of Boletus gabretae are presented, and its placement in the genus Neoboletus is suggested. Cyanoboletus is confirmed as a strongly supported generic clade encompassing 21 monophyletic species-level clades, 14 of which represent known species, and seven are undescribed taxa. The synonymy of Cupreoboletus with Cyanoboletus is also verified. This publication provides the tools to delimit Cyanoboletus species that have important conservation value, which can be used by conservationists, ecologists, and citizen scientists. It also highlights species-specific arsenic hyperaccumulation in C. pulverulentus, contributing to a better understanding of fungal metal uptake. Our study indicates that within Cyanoboletus, only C. pulverulentus demonstrates this characteristic and is the only known member of Boletales that possesses a high arsenic accumulation ability. Full article

Background/Objectives: Staphylococcus aureus, particularly methicillin-resistant strains, is a leading cause of severe pneumonia. Understanding local molecular epidemiology, including virulence gene profiles and antimicrobial resistance (AMR) mechanisms, is crucial for effective infection control. This pilot study aimed to characterize S. aureus isolates from pneumonia patients in Karaganda, Kazakhstan. Methods: We collected 48 respiratory samples from patients with pneumonia across three medical institutions. Bacterial identification was performed using MALDI-TOF MS. Antimicrobial susceptibility testing (AST) was carried out using European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. Whole-genome sequencing of S. aureus isolates was conducted on an Ion Torrent S5 platform. Genomic analysis included multilocus sequence typing (MLST), identification of virulence and AMR genes, and phylogenetic reconstruction. Results: S. aureus was identified in 14.6% (n = 7) of pneumonia cases included in this study. All isolates (100%, n = 7) were phenotypically resistant to benzylpenicillin. The mecA gene was detected in 57.1% of isolates (n = 4), while phenotypic resistance to methicillin was observed in 28.6% (n = 2) of the isolates. Resistance to azithromycin (57.1%, n = 4) and levofloxacin (42.9%, n = 3) was observed among the isolates. Two isolates (28.6%) were multidrug-resistant (MDR). Genomic analysis revealed the prevalence of the ST22 clone (57.1%, n = 4) in the studied cohort. Other sequence types were ST97, ST8, and ST45 (14.3% each). Phylogenetic analysis showed clustering consistent with MLST profiles. All isolates carried a conserved core virulence arsenal, including hemolysin (hla, hlg), biofilm-forming genes (icaADBC), immune evasion genes (sak, scn), and iron acquisition genes (isd). The Panton–Valentine leukocidin (PVL) genes were detected in three isolates. AMR gene analysis revealed the ubiquitous presence of mepA and tetracycline efflux pump genes, along with regulatory genes (arlRS, mepR, mgrA). The blaZ and ermA genes were not detected despite high phenotypic resistance to penicillin and macrolides. Conclusions: This study reports the identification of the virulent and resistant ST22 S. aureus clone in pneumonia cases in Karaganda, Kazakhstan. The discordance between phenotypic and genotypic AMR profiles underscores the necessity for integrated diagnostic approaches. Full article

Lysobacter antibioticus Hz25 is a novel strain that was isolated from the rhizosphere of the relict endemic plant Hedysarum zundukii Peschkova (Fabaceae), which grows on carbonate soils in the Baikal region of Russia. This work presents the complete genome sequence of Hz25 (5.98 Mb, 66.94% GC), which was obtained using a hybrid assembly method combining Oxford Nanopore and Illumina sequencing. Phylogenetic analysis based on 47 Lysobacter genomes and an average nucleotide identity (ANI) value of 96% confirmed its affiliation with L. antibioticus. A comparative pan-genome analysis with three closely related strains (13-6, 76, and ATCC 29479) identified 554 strain-specific genes. This significant genomic plasticity likely reflects adaptation to the sharply continental climate, high insolation, and low free iron content of the native soil. The genome encodes a comprehensive micropredator arsenal, including: seven chitinase genes (GH18 and GH19 families); bacteriolytic enzymes (Blp, L1, L4, Ami); a complete type III secretion system (T3SS) with predicted effectors; type IV pili (including the PilZ-PilB regulatory complex); and siderophore biosynthesis genes (lysochelin). The genome contains genes ars of an arsenic resistance system, but lacks the ACR3 efflux pump, suggesting that these genes may have alternative functions. Genes involved in calcium homeostasis (Excalibur domain, Na⁺/Ca²⁺ antiporter) were also identified. These features make Hz25 a promising candidate for biocontrol applications in cold climates and metal-contaminated environments. Full article

Arsenopyrite (FeAsS) is an important sulfide that holds gold in orogenic systems. Its arsenic content is often used as a proxy for gold fertility. However, arsenopyrite from the Um Rus gold deposit in Egypt’s Central Eastern Desert shows a complicated gold distribution that makes simple Au-As correlations hard to make. Integrated electron microprobe analysis (EMPA), laser ablation ICP-MS, and principal component analysis (PCA) reveal three unique textural and geochemical domains. Fine-grained arsenopyrite inclusions within pyrite aggregates (28–31 at% As) are devoid of detectable gold; PCA elucidates 84% of their variance through Fe–S versus Co-As substitution (PC1: 61.8%) and Pb-decoupled variability (PC2: 22.2%), suggesting crystallization from a Co-rich, Au-poor fluid. On the other hand, coarse oscillatory-zoned arsenopyrite can hold up to 6154 ppm of invisible gold. This is because of a moderate Au-As substitution (R = 0.41063, p = 0.08074) that was overprinted by a separate Au-Ag-Sb-Te hydrothermal pulse (Au–Ag: R = 0.97762; Au–Sb: R = 0.97608). PCA finds four parts (72.8% variance): Ag-Cu-As associations (PC1: 25.1%), Te versus Bi-Au signatures (PC2: 17.8%), Fe–S stoichiometry (PC3: 17.1%), and an Au versus Pb-decoupled event (PC4: 12.9%). This shows that minerals formed in more than one stage. Irregular As-rich overgrowths, containing ≤950 ppm gold and lacking significant Au–As correlation (R = −0.14011, p = 0.56726), show PCA (74.3% variance) that highlights S-As contrasts (PC1: 25.2%), Co-Ni enrichment (PC2: 18.8%), Cu-Fe-Ni associations (PC3: 16.2%), and a late Au-decoupled event (PC4: 14.2%), indicating barren recrystallization. These results show that just adding arsenic is not a good way to tell if gold is fertile. The highest amounts of invisible gold, on the other hand, are found in oscillatory-zoned domains with Ag-Sb-Te signatures. This research highlights the importance of combining PCA, geochemistry, and microtextures to differentiate auriferous from barren arsenopyrite, thereby enhancing exploration methodologies for structurally intricate orogenic gold systems. Full article

Dissolved silicic acid (Si) in groundwater can reduce the As-removal performance of adsorbents used for treating contaminated water. However, its effects on Mg-based adsorbents remain largely unexplored. In this study, As-removal tests were conducted under various test conditions to evaluate the suitability of Mg-based adsorbents (MgO, Mg(OH)₂, and MgCO₃) for the purification of As-contaminated water in the presence of Si. As-removal performance varied significantly depending on the Mg-based adsorbent type and dosage (W_Ad0/V), As valence, and the initial As and Si (C_Si0) concentrations. In some cases, As removal improved at relatively low C_Si0; however, overall performance decreased with increasing C_Si0 for all Mg-based adsorbents. Moreover, compared with Mg(OH)_2, the performance of MgO and MgCO₃ was more strongly affected by Si. This inhibition is attributed to competition between Si and As for adsorption sites on the adsorbent surface. Furthermore, for MgO and MgCO₃, the amount of As removed by coprecipitation with secondarily generated Mg(OH)₂ aggregates was inferred to decrease with increasing C_Si0, because higher C_Si0 lowered the solution pH. Overall, MgO and Mg(OH)₂ can function effectively as adsorbents for As treatment when W_Ad0/V is appropriately selected, considering the range of Si concentrations typically found in groundwater. Full article

Groundwater in uranium mining areas is highly sensitive to pollution by radionuclides and toxic elements, especially under in situ leaching mining, which increases their mobility. This study assesses the radiological and chemical features of water sources in the Chu-Sarysu uranium province (Kazakhstan) by evaluating the annual effective dose (AED) from radionuclide ingestion. In total, 98 water samples from boreholes, wells and rivers were analyzed for total alpha and beta activity, followed by radionuclide and chemical analysis of selected samples. High total alpha activity was detected mainly in groundwater and was associated with radium mobilization. On average, ²²⁸Ra constituted between 50% and 60% of the total AED, whereas ²²⁶Ra contributed between 35% and 45%, with uranium isotopes contributing less than 5%. The total AED value for the groundwater ranged from 0.14 to 0.52 mSv/year at average water use, but only one borehole sample had 9.07 mSv/year, reflecting a localized anomaly. Additionally, arsenic, manganese, and mercury displayed high spatial variability. These findings underscore radium’s significant role in radiation exposure and emphasize the need for comprehensive monitoring of both radiological and chemical contaminants in groundwater systems. Full article