Human health risks associated to trace elements and metals in commercial fish from the Brazilian Amazon.

Fish constitutes the main protein source for the Amazonian population. However, the impact of different anthropogenic activities on trace element and metal accumulation in fish and their risks for human health at a regional scale remain largely unexplored. Here we assessed exposure levels of 10 trace elements and metals (Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Pb, and Hg) in 56 samples belonging to 11 different species of fish from the Brazilian Amazon. We studied the relationship between exposure levels, fish origin, and fish feeding habits, and assessed toxicological and carcinogenic risks for the Amazonian population. No significant correlation was found between sampling site and exposure levels to the studied elements, but a significant difference was found between the accumulation of some metals and the position of the fish species in the food chain. The concentrations of Cr and Hg in fish flesh were found to exceed the Brazilian limits for human consumption. This study shows that current fish consumption patterns can lead to estimated daily intakes of Hg, As and Cr that exceed the oral reference dose, thus posing a toxicological concern. Furthermore, carcinogenic risks may be expected due to the continued exposure to Cr and As. The results of this study show that the consumption of wild caught fish in the Amazon region should be controlled. Moreover, continued monitoring of trace element and metal contamination in fish and on the health of the Amazonian population is recommended, particularly for riverine and indigenous communities.

Experimental design and multiple response optimization of batch leaching tests of volcanic ashes.

Volcanic eruptions can release large amounts of tephra, lava, and gases, drawing attention due to their magnitude, energy, and impact on life and the environment. Among the most documented and sometimes dramatic effects of volcanic ashes are those linked to the input of diverse elements in the environment, which are released as a consequence of ash weathering. Laboratory studies have been conducted to investigate and predict the environmental input of chemical elements from volcanic ashes. This research paper describes the optimization of batch leaching tests used to investigate the release of ions from ashes collected in the Andes Cordillera after the eruption of the Puyehue volcano in 2011. Chemometric multivariate strategies were employed to evaluate the influence of variables affecting the leaching of volcanic ash. The effects of the main variables, namely contact time, the acidity of the leaching agent, the solid/liquid ratio, the particle size, and the stirring speed, were studied in leaching tests. To determine the optimal conditions for selected metal determinations, we employ Darringer's desirability function, which allows for the simultaneous optimization of the selected responses (element concentrations during the leaching process). Multielemental analysis (Na, Mg, Al, Si, P, Cl, K, Ca, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Cd, Hg, Tl, and Pb) was quantified by ICP-MS (inductively coupled plasma-mass spectrometry) following adequate dilution of test leaching. These results established the optimal experimental conditions for leaching volcanic ash. The most significant variables were the solid/liquid ratio and the stirring speed, resulting in two groups of elements with an adequate global desirability function (D) value.

Frog hepatic health and metal pollution: An assemblage-level approach in a hotspot in southeastern Brazil.

Chemical pollutants include the harmful effects of various substances on soils, water bodies, and biodiversity. Amphibians are one of the most endangered groups of vertebrates and are impacted by chemical pollutants in various ways due to their complex life cycles. Since trace pollutant concentrations vary across environments, different frog ecomorphs (classified by their microhabitat use) may have different exposures. We aimed to determine the association between frog ecomorphs and the occurrence of histopathological hepatic lesions (HHLs) as an indicator of contaminant exposure. We focused on small forest streams near a large urban region in Brazil, heavily polluted in the 1980s. We examined 104 frog specimens from various families. All specimens exhibited HHLs, with melanomacrophages being the most common (n = 99). Arboreal frogs exhibited more vascular congestion, while terrestrial frogs showed structural hepatic damage. Higher cobalt levels were linked to increased liver necrosis in arboreal frogs and structural issues in both arboreal and terrestrial frogs. Cadmium was associated with hepatitis in terrestrial frogs. Although metal levels had no significant effects on rheophilic frogs, the prevalence of hepatitis and necrosis indicated complex exposure pathways. Iron and aluminum were linked to fewer lesions in rheophilic frogs, suggesting resilience. The high prevalence of HHLs signals an ongoing issue, with variations among ecomorphs suggesting differential exposure to pollutants and posing a complex challenge for community conservation.

Reconstructing 90 years of anthropogenic activities in a subtropical reservoir: a chemometric and paleolimnological perspective.

Environmental reference conditions (RC) and historical trends are crucial for assessing the degree of freshwater impact and formulating restoration measures. This is particularly relevant for freshwater systems used as potable water sources. Using sediments from the Carlos Maggiolo reservoir (Minas, Uruguay), located in a watershed with a mining history, this study aimed to (1) establish metal (As, Cr, Cu, Ni, Pb, and Zn) RC using a predicted interval (PI) chemometric technique; (2) evaluate metal enrichment and toxicity over time and space; and (3) assess environmental changes examining geochemical proxies. Surface sediments from 29 stations were used to establish RC and a core from the dam area was sampled to infer past conditions. The sediments were submitted to partial digestion and analyzed by inductively coupled plasma optical emission spectrometry- ICP-OES. Enrichment factor (EF) calculated using both PI and bottom core values did not show significant differences over time. Over space and time, most metals primarily originated from natural sources (EF < 2). The PI in mg/kg was Cr: 23.74-37.32; Cu: 25.75-48.99; Ni: 16.29-25.55; Pb: 7.63-13.75; and Zn: 94.34-174.80. A stratigraphically constrained cluster analysis corroborated by a permutational multivariate analysis of variance categorized the reservoir into two zones: Zone I, before reservoir operation to ~ 1996, and Zone II from ~ 1997 to 2017. The average concentrations of the main metals of toxicological interest in zones I and II, respectively, were as follows: Cr 37.60 ± 1.59, 34.54 ± 1.49 mg/kg; Cu 49.76 ± 2.84, 44.55 ± 2.70 mg/kg; Ni 24.11 ± 0.67, 22.53 ± 1.22 mg/kg; Pb 12.40 ± 0.63, 13.52 ± 0.82 mg/kg; Zn 99.25 ± 3.12, 93.86 ± 4.42 mg/kg; Mn 1160.56 ± 68.88, 1441.61 ± 83.55 mg/kg; and P 1243.21 ± 271.56, 1128.42 ± 183.10 mg/kg. According to a principal component analysis, the period preceding reservoir operation until ~ 1985 was linked to mining activities and application of Cu2SO4, and the period from 1985s to 2000 was influenced by C and P concentrations due to increasing agricultural and afforestation activities in the watershed that consume P fertilizers. The most recent period, from 2000 to ~ 2017, was characterized by an increase in sedimentation rates mainly associated with erosion, particularly in the agricultural areas. This subsequent soil loss in the watershed could compromise the reservoir's useful life. This study contributes to a better understanding of metal geochemistry in subtropical reservoirs and aids in formulating effective recovery and restoration measures.

Accelerated Longitudinal Glycemic Changes in Relation to Urinary Toxic/Essential Metals and Metal Mixtures Among Mexican Americans Living in Starr County, Texas.

OBJECTIVE: Metal and metalloid exposures (hereafter "metals") are associated with adverse health outcomes, including type 2 diabetes; however, previous studies were largely cross-sectional or underpowered. Furthermore, underserved racial and ethnic groups are underrepresented in environmental health research despite having higher rates of type 2 diabetes and a greater risk of metal exposures. Consequently, we evaluated continuous glycemic traits in relation to baseline urinary toxic metal, essential metal, and metal mixtures in a cohort of Mexican American adults. RESEARCH DESIGN AND METHODS: A total of 510 participants were selected based upon self-reported diabetes status and followed over 3 years. Urinary metals were assessed at baseline. Linear mixed-effects models were used to estimate per-month changes in hemoglobin A1c, fasting plasma glucose, and postload glucose in relation to urinary metal levels. Multiple statistical approaches were used to assess the associations between glycemic traits and metal mixtures. RESULTS: After adjustment, higher urinary levels of arsenic, selenium, copper, molybdenum, nickel, and tin were associated with faster increases in measures of glycemia. The toxic metal mixture composed of arsenic, lead, cadmium, nickel, and tin was associated with faster increases in postload glucose. Using postload glucose criteria, highest versus lowest arsenic was predicted to accelerate conversion of normoglycemia to prediabetes and diabetes by 23 and 65 months, respectively. CONCLUSIONS: In this underrepresented, high-risk Mexican American population, exposure to toxic metals and alterations in essential metal homeostasis were associated with faster increases in glycemia over time that may accelerate type 2 diabetes development.

Metal artifact reduction tool and mA levels impact on the diagnosis of fracture extension in endodontically treated teeth using cone-beam CT.

AIM: To evaluate the influence of different levels of metal artifact reduction (MAR) tool and milliamperage (mA) on the diagnosis of fracture extension in endodontically treated teeth using cone beam CT (CBCT). MATERIALS AND METHODS: Ten maxillary premolars were endodontically treated and positioned in the empty sockets of a human maxilla covered with wax. CBCT acquisitions were performed using the Eagle Edge device (Dabi Atlante, Brazil) adjusted to 120 kVp, FOV of 4 × 6 cm, exposure time of 24 s and voxel size of 0.2 mm in 8 different conditions with different MAR (1, 2 and 3) and mA (3.2 and 6.3) levels. Crown-root fractures were simulated in the universal testing machine, and CBCT images were acquired again. Five radiologists evaluated the presence and extension of fractures with a 5-point scale. Statistical analysis was performed by analysis of variance, Tukey and Kappa test (α = 0.05). RESULTS: Although different mA levels did not significantly (p > 0.05) affect the diagnosis values for fracture presence and extension, when evaluated the different levels of MAR, AUC and sensitivity showed significantly higher values (p < 0.05) for MAR 0 using 6.3 mA and kappa agreement showed significantly higher values (p < 0.05) for MAR 0 and 2 using 6.3 mA. CONCLUSIONS: Although mA levels do not have a diagnostic effect when isolating the MAR level; in 6.3 mA, MAR 0 and 2 can positively influence the diagnosis of fracture extension in endodontically treated teeth using CBCT. CLINICAL RELEVANCE: The isolate evaluation of dental fracture presence can overlook diagnostics error of its extension.

Blood levels of 21 metals and metalloids in riverside villagers of the Brazilian Amazon: A human biomonitoring study with associations with sociodemographic, dietary, and lifestyle factors.

Human biomonitoring of toxic and essential trace elements is critically important for public health protection. Amazonian riverine communities exhibit distinctive dietary patterns, heavily reliant on locally sourced fish, fruits, and vegetables. These habits may result in unique exposure profiles compared to urban populations. However, comprehensive assessments of their exposure to toxic and essential metals are lacking, representing a critical gap in understanding the health risks faced by these communities. This study aimed to establish baseline levels of 21 metals and metalloids in human blood and explore the influence of sociodemographic factors, dietary habits, and lifestyle choices as potential sources of exposure to these elements. A cross-sectional biomonitoring investigation was conducted with 1,024 individuals from 13 communities in the Tapajós and Amazon Basins (Pará, Brazil). Most of the elements in study was determined for the first time in the region. Blood samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The levels of all elements were summarized by quantiles and compared with cutoff values from other Brazilian populations. Multiple linear regression was used to assess possible associations between element concentrations and sociodemographic characteristics, dietary habits, and lifestyle choices. High detection rates (64%-100%) were observed, indicating the widespread presence of these elements. Elevated blood concentrations were found for mercury (median 21.1 µg.L-1, interquartile range: 12-34 µg.L-1), selenium (median 166 µg.L-1, interquartile range: 137-208 µg.L-1), and lead (median 34 µg.L-1, interquartile range: 20.8-64 µg.L-1). Regression analysis revealed a positive association between mercury levels and fish consumption, while manioc flour intake showed no relationship to lead levels. In conclusion, our findings emphasize the need for continued monitoring and public policy development for these vulnerable populations. Further studies should assess long-term trends and investigate the health implications of prolonged exposure to diverse chemicals in Amazonian riverside communities.

Potential of metal recovery from printed circuit boards in Brazil.

In this study, the generation of domestic waste electrical and electronic equipment (WEEE) and waste printed circuit board (WPCB) were estimated, from 2015 to 2030. Based on the number of EEE put on the Brazilian market, the possession rate in the Brazilian households and obsolescence amounts of five EEE types were estimated using time series. The results show that, between 2015 and 2030, the quantity of WEEE generated per year will increase from 131.87 kt to 195.22 kt. In this period, WPCB generation will stay around 10% of WEEE generation. Additionally, this study shows that the urban mining potential of the materials recoverable from WPCB can be an important revenue source, with environmental benefits deriving from energy savings and a reduction in CO2 emissions. The results of this study provide a quantitative basis that may help decision makers develop strategic policies for WEEE management, considering material circularity.

Toxicity of isolated and mixed metals to a native Amazonian ostracod and ecological risk assessment.

In recent decades the Amazonian ecosystem has received large amounts of domestic and industrial effluents, as well as mining-related waste contributing significant quantities of metal to water bodies. Thus, the main objective of the study was to verify the sensitivity of a native Amazonian ostracod (Strandesia rondoniensis) species to isolated and mixed metal salts (CuSO4; ZnCl2; CdCl2 and HgCl2). The sensitivity will be compared to other species using species sensitivity distributions (SSDs) for an ecological risk assessment (ERA). The experiment consisted of simultaneously exposing each metal alone and in mixture, through a factorial design for toxicity with 25 different combinations for 48 h. For the ERA, metal concentrations measured in the water of various aquatic environments in the Amazon basin were considered based on the risk quotient values. The results showed that the metal toxicity gradient was Cd>Hg>Cu>Zn, respectively. The toxicity in the mixture showed that the combination of Cu-Cd and Cu-Zn better fit the model (CA), indicating mainly synergism when copper predominated in the mixture. Meanwhile, the Cu-Hg interaction fit the model better (IA), again indicating synergism when copper was at a higher concentration. The ERA showed a high risk (RQ > 1) for the Cd, Cu, and Hg metals.

Current Strategy for Targeting Metallo-ß-Lactamase with Metal-Ion-Binding Inhibitors.

Currently, antimicrobial resistance (AMR) is a serious health problem in the world, mainly because of the rapid spread of multidrug-resistant (MDR) bacteria. These include bacteria that produce ß-lactamases, which confer resistance to ß-lactams, the antibiotics with the most prescriptions in the world. Carbapenems are particularly noteworthy because they are considered the ultimate therapeutic option for MDR bacteria. However, this group of antibiotics can also be hydrolyzed by ß-lactamases, including metallo-ß-lactamases (MBLs), which have one or two zinc ions (Zn2+) on the active site and are resistant to common inhibitors of serine ß-lactamases, such as clavulanic acid, sulbactam, tazobactam, and avibactam. Therefore, the design of inhibitors against MBLs has been directed toward various compounds, with groups such as nitrogen, thiols, and metal-binding carboxylates, or compounds such as bicyclic boronates that mimic hydrolysis intermediates. Other compounds, such as dipicolinic acid and aspergillomarasmin A, have also been shown to inhibit MBLs by chelating Zn2+. In fact, recent inhibitors are based on Zn2+ chelation, which is an important factor in the mechanism of action of most MBL inhibitors. Therefore, in this review, we analyzed the current strategies for the design and mechanism of action of metal-ion-binding inhibitors that combat MDR bacteria.

The impact of settleable atmospheric particulate on the energy metabolism, biochemical processes, and behavior of a sentinel mangrove crab.

We use the sentinel mangrove crab, Minuca rapax, as a model to investigate the effects of metallic settleable particulate matter (SePM) on wetland. Multiple levels of energetic responses, including (i) metabolic rate and energy budget, (ii) oxidative stress, and (iii) behavioral response by righting time, were assessed as well as the metal and metalloid content in crabs exposed to 0, 0.1 and 1 g.L-1 of SePM, under emerged and submerged conditions over five days, simulating the rigors of the intertidal habitat. Al, Fe, Mn, Cr, and Y exhibited a concentration-dependent increase. Metal concentrations were higher in submerged crabs due to the continuous ingestion of SePM and direct exposure through gills. Exposure concentration up to 1 g.L-1 decreased metabolic rate and enzymatic activities, reduced assimilation efficiency and energy for maintenance, and induces a slower response to righting time, probably by metal effects on nervous system and energy deficits. In conclusion, SePM exposure affects the redox status and physiology of M. rapax depending on he submersion regime and SePM concentration. The disruption to the energy budget and the lethargic behavior in M. rapax exposed to SePM implies potential ecological alterations in the mangrove ecosystem with unknown consequences for the local population.

Arsenic and metal levels in snake tissues from Lagoa Santa Karst, Brazil.

Concentrations of one metalloid (As) and eight metals (Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) were determined in tissues (muscle, liver, and kidney) of eight snake species (Bothrops neuwiedi, Crotalus durissus, Dipsas mikanii, Epicrates crassus, Helicops modestus, Micrurus carvalhoi, Oxyrhopus guibei, and Oxyrhopus trigeminus) from Lagoa Santa Karst. Except for Cu and Zn, all other analyzed elements were detected in concentrations within the ranges previously reported for snakes inhabiting polluted areas, emphasizing Hg (specific Hg mean concentrations varied from 0.87 to 9.76 µg g-1 d.w). The highest mean concentrations of all elements except Zn were found in muscle samples of the false corals O. guibei (means ranged from 2.01 [Pb] to 9.76 [Hg]). The highest Zn mean concentration (13.77 µg g-1 d.w) was detected in the kidney of the water snake H. modestus. No significant correlation was found between element concentrations and body size for all species. Significant interorgan differences were observed for As, Cr, Cu, Hg, Mn, Pb, and Zn concentrations in the three tissues in H. modestus. Significant interspecific differences were found in at least one organ for all elements. Significant pairwise differences were found between diet specialist species and between these species and broader diet species, while no significant difference was found between the broader diet species. The bioaccumulation of As and metals in snakes from Lagoa Santa Karst could be associated with natural rock dissolution and erosion processes but also with the wide-scale mining in the region and the increased agriculture and urbanization.

Adsorption and ion exchange of toxic metals by Brazilian clays: clay selection and studies of equilibrium, thermodynamics, and binary ion exchange modeling.

In this study, four Brazilian clays (Bofe, Verde-lodo, commercial Fluidgel, and expanded commercial vermiculite) were evaluated for their adsorptive capacity and removal percentage in relation to different toxic metals (Ni2+, Cd2+, Zn2+, and Cu2+). The best results were obtained by expanded vermiculite, with cadmium removal reaching values of 95%. The most promising clay was modified by the sodification process, and the metal cadmium was used to evaluate the ion exchange process. The clays expanded vermiculite (EV) and VNa-sodified vermiculite were evaluated by equilibrium study at 25, 35, and 45 °C. At 25 °C, EV obtained a maximum adsorption capacity of 0.368 mmol/g and sodified vermiculite 0.480 mmol/g, which represents an improvement of 30.4% in modified clay capacity. At 45 °C, the sodified vermiculite reached 0.970 mmol/g adsorption capacity. The Langmuir, Redlich-Peterson Freundlich, and Dubinin-Raduskevich models were adjusted to the results. Langmuir provided the best fit among the models. The thermodynamic quantities (ΔS, ΔH, and ΔG) demonstrated that the process is spontaneous and endothermic and the metal is captured by physisorption and chemisorption in the studied temperature range. For the ion exchange equilibrium, the binary Langmuir and binary Langmuir-Freundlich models were adjusted to the expanded vermiculite and sodified vermiculite isotherms, respectively. Both models were predictive. Thermal analysis indicated good heat resistance even after material modification. The apparent and real densities demonstrated that after each treatment or contamination, the clayey material undergoes contraction in its structure. An improved efficiency of the adsorbent was found after sodification.

Waterborne metal levels in four freshwater lakes from Harmony Point, Nelson Island, Antarctica.

The aim of this study is to analyze the waterborne metal levels in four lakes (one endorheic and three exorheic) of Harmony Point, Nelson Island, Antarctica. Water samples were analyzed by using a quadrupole type inductively coupled plasma mass spectrometer and an inductively coupled plasma optical emission spectrometer. The levels of As, Cu, Mn, Mo, and V were significantly lower and those of Cr, Mg, Na, and Sr were significantly higher in the endorheic lake than in the other lakes. Most water samples presented levels of Ag, Be, Cd, Pb, Se, Tl, and U below the limit of quantification, while for Ba, Co, and Ni around half of the samples were below this limit. The waterborne metal levels were not significantly different between the exorheic lakes. Waterborne metal levels in the freshwater lakes from Harmony Point did not show any clear relationship with their levels in the soil of the region or with bird guano, and overall, their levels indicate an environment without anthropogenic influence. Apparently, the Na levels are influenced by salt spray from the ocean, as they are related to the distance of the lakes from the ocean.

Metal(loid) bioaccessibility and risk assessment of ashfall deposit from Popocatépetl volcano, Mexico.

Ash emission from volcanic eruptions affects the environment, society, and human health. This study shows the total concentration and lung bioaccessible fraction of eight potential toxic metal(loid)s in five Popocatépetl ashfall samples. Mineralogical phases and particle size distribution of the ashfall were analyzed by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) techniques, respectively. The bioaccessibility test of Gamble solution (GS) and Artificial Lysosomal Fluid (ALF) were conducted to simulate extracellular (pH 7) and intracellular (pH 4.5) conditions, respectively. The studied metal(loid)s showed the following total concentration (mg kg-1): 1.98 (As), 0.17 (Cd), 134.09 (Cr), 8.66 (Cu), 697.33 (Mn), 55.35 (Ni), 8.77 (Pb), and 104.10 (Zn). Geochemical indices suggested that some metal(loid)s are slightly enriched compared to the local soil background concentrations. Several mineralogical phases were identified in the collected ashfall deposits, such as plagioclase, pyroxene, and Fe-Ti oxide, among others. According to the risk assessment results, the non-carcinogenic risk related to ashfall exposure returns an HQ > 1 for children. In contrast, the estimation of carcinogenic risk was found to be within the tolerable limit. Metal(loid)s showed low bioaccessibility (< 30%) in GS and ALF, with the highest values found in ALF solution for As (12.18%) and Cu (7.57%). Despite their metal-bioaccessibility, our findings also showed that dominant ash particle size ranged between fine (< 2.5 µm) and extremely fine (< 1 µm), considered highly inhalable fractions. The results obtained in this work indicate that volcanic ashes are bioinsoluble and biodurable, and exhibit low bioaccessibility when in contact with lung human fluids.

Blood levels of metallic chemical element exposure patterns and associated factors in a population living in an Industrial District in Brazil.

AIM: to estimate the level of metallic chemical elements in the population living in the Steel company vicinity in Santa Cruz, Rio de Janeiro, Brazil; and estimate the association between exposure to the Steel company and the blood metals concentrations patterns. METHOD: A cross-sectional study was carried out on 463 individuals aged 18+ years old residing 1+ years in the Steel company vicinity. Mg, Be, Co, Ba, Ni, Cd, Al, and Pb were assessed in blood by DRC-ICP-MS. Metallic chemical element concentration patterns were obtained by exploratory factor analysis in the studied population. Exposure was set as the distance (Km) from each participant's residence to the Steel company in Santa Cruz, georeferenced by GPS. The outcome was set as the positive factor loadings in the factor analysis, including Mg and Be (Factor-1), Co, Ba, and Ni (Factor-2), Cd, Al, and Pb (Factor-4). Crude and adjusted OR, and their respective 95 %CI, were estimated to explore associations between independent variables and the exposures to metallic elements positively associated with the factors using polychotomous logistic regression. RESULTS: A reduction of 19 % was found between each km distance from the residence and the Steel company and P50 concentration of Cd, Al, and Pb (ORP50=0.81; 95 %CI:0.67-0.97), after adjusting by age, sex, and smoking. No statistically significant associations were observed for the distance from residences and the Steel company, after adjusting for age, gender, having a domestic vegetable garden and chewing gum for Mg and Be concentrations (Factor-1) (ORP50=0.84; 95 %CI:0.70-1.01; ORP75=1.10; 95 %CI:0.91-1.34); nor for Co, Ba and Ni (Factor-2) blood concentrations(ORP50=1.10; 95 %CI:0.91-1.33; ORP75=1.03; 95 %CI:0.84-1.26), in the adjusted analysis. CONCLUSIONS: For each Km distance from residences to the Steel company, a 19 % reduction in the risk of Cd, Al, and Pb blood concentration was observed in the population living in Santa Cruz, Rio de Janeiro, Brazil.

Long-term performance: strength and metal encapsulation in alkali-activated iron ore tailings.

Understanding the strength behavior and leaching characteristics of mining tailings stabilized with alkali-activated cements in the short, medium, and long term is crucial for the feasibility of material applications. In this context, this study assessed the stabilization/solidification of iron ore tailings (IOT) using alkali-activated binder (AAB) composed of sugarcane bagasse ash and eggshell lime at curing times of 7, 28, 60, 90, 180, and 365 days. Additionally, leaching tests were conducted, along with the examination of possible changes in the chemical and mineralogical composition resulting from exposure to acidic environments. Tests included unconfined compression strength (UCS), leaching, X-ray diffraction, and Fourier-transform infrared spectroscopy for the IOT-AAB mixtures. The highest increase in UCS was observed between 7 and 60 days, reaching 6.47 MPa, with minimal variation thereafter. The AAB-bonded IOT exhibited no metal toxicity over time. Elements Ba, Mn, Pb, and Zn present in IOT and ash were encapsulated in the cemented matrix, with complete encapsulation of all metals observed from 90 days of curing time. The mineralogy of the stabilized/solidified tailings showed no changes resulting from leaching tests. Characteristic bands associated with the presence of N-A-S-H gel were identified in both pre-leaching and post-leaching samples for all curing times analyzed. Exposure to acidic environments altered bands related to carbonate bonds formed in the IOT-AAB mixture.

Use of lichens as bioindicators of contamination by agrochemicals and metals.

The presence or absence of lichens serves as an indicator of the condition of an ecosystem and the degree to which it is contaminated by various agents, such as agrochemicals and metals. Evaluating the use of lichens as bioindicators of agrochemical contamination could provide a more comprehensive perspective of current contamination levels. Monitoring was conducted over a 4-month period in two study areas: one was a well-conserved area contaminated by metals, and the other was an area surrounded by agricultural crops contaminated by agrochemicals. Data on the presence and abundance of lichens in each study area were recorded at 10 monitoring points, a procedure that was repeated 16 times (every 15 days), and concentrations of heavy metals and "organophosphate" agrochemicals in the lichens collected were measured by means of Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-OES) and Gas Chromatography (GC), respectively. Generalized linear mixed models were used to assess abundance and richness, while general linear mixed models were used to attain Shannon diversity and Simpson dominance indices. Moreover, a multivariate analysis was performed in order to compare the lichen communities in both areas. The results indicated differences between the area contaminated by metals and that contaminated by agrochemicals in terms of abundance and Simpson's dominance index, while no differences were found in the case of the richness and diversity models. The PERMANOVA analysis additionally showed differences between the lichen communities in the two areas. The results also demonstrated that Canoparmelia caroliniana bioaccumulated metals in both areas. The levels of barium, cadmium, and sodium were higher in the area contaminated by metals, while concentrations of chromium and copper were higher in the area contaminated by agrochemicals. Finally, the concentrations of agrochemicals were higher in the area contaminated by agrochemicals and included toxic substances such as Methylparathion and Parathion, which are prohibited in Ecuador. In conclusion, this research underscores the importance of lichens as precise indicators of environmental health and contamination by agrochemicals and metals.

Teeth and alveolar bones as tracers of metals and radionuclides in inhabitants of a uranium region.

Biodosimetry can define risks in inhabitants of areas with potential contaminants, ensuring environmental protection and living conditions due to toxic and radioactive effects. This study aimed to evaluate metals and radionuclides in dental structures and alveolar bones in residents of a uranium area in Paraíba and Pernambuco, Brazil. Eighty-nine specimens were pulverized, fractionated, and chemically prepared for analysis by EDXRF, FAAS, and ICP-MS. Levels of Ca, Cu, Fe, Si, Mn, Ni, Pb, Sr, Ti, V, Zn, K, Mn, Th, and U were investigated. Higher concentrations were measured for Ca, with an average of 272,986.4 mg kg-1. Ni presented in lower concentrations, with an average of 30.4 mg kg-1. For U, concentrations ranged from 1.5 to 145.0 mg kg-1, with more than 27% of the samples above the reference value of 8.1 µg kg-1. For Th, almost 38% of the results were above the limit of 3.5 µg kg-1. In the bone spicules, the contents of U and Th ranged from 45.1 to 1451.2 µg kg-1 and from 7.5 to 78.4 µg kg-1, in this order. The levels of radionuclides were more expressive for the teeth collected in São José do Sabugi, suggesting contamination through food and water consumption. In the bone spicules, the levels of U were up to 179 times higher than the safety limit. The results indicate a possible risk of contamination with probable induced radiobiological effects.