Microplastics (MPs), arsenic (As) and cadmium (Cd) ubiquitously co-exist in aquatic systems, establishing interactions and posing potential health risk due to their pivotal roles in the co-transportation processes of contaminants, yet available information still remains limited. This study investigated the adsorption patterns of As(V) and Cd(II) on polyamide (PA-MPs) and polylactic acid (PLA-MPs), as well as assessed their bioaccessibility and human health risks using batch experiments, spectroscopic characterizations and density functional theory (DFT) calculations. The results demonstrated that PLA-MPs had higher adsorption affinity towards Cd(II) than PA-MPs, and As-Cd could be co-sorbed on MPs in their coexisting systems probably due to ternary MP-Cd-As complexes formation, reaching 530.17 and 192.55 µg/g, respectively. Cd(II) bioaccessibility in co-sorbed PA-MPs (3.22-14.65 %) was significantly lower than that in co-sorbed PLA-MPs (15.46-82.38 %). This phenomenon was facilitated by the formation of more stable molecular structure (PA-Cd-As) with a higher binding energy (-1.54 Ha) as calculated by DFT simulations. Besides, the extensive erosion and degradation on PLA-MPs surface affected by digestive enzymes and gut microbiota also accelerated Cd(II) release, thereby posing greater health risks. Overall, this study emphasized the significance of understanding the MP-metal(loid) interactions when handling with the health risk assessment in co-contaminated water.

The toxicity of environmental arsenic (As) exposure can be modulated by the gut microbiota via As reduction, methylation, and thiolation reactions. However, the precise role of food components in these metabolic processes remain unclear. This study systematically explored the impacts of 24 representative food components on As metabolism by human gut microbiota. Based on the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) model, As bioaccumulation, As speciation profiles, gut microbiota composition, and short-chain fatty acids were quantified to assess their interactions. Of the 24 food components, 15 demonstrated alterations in As metabolism by the gut microbiota. Soy protein, vitamin B12, and erythritol increased methyl arsenic by 8.80-85.40%, while butyric acid (a key energy metabolite) rose 7.78- and 17.13-fold with erythritol or soy protein. The relative abundance of Sporanaerobacter, Stenotrophomonas, and Pseudomonas demonstrated strong positive correlations with As methylation (r = 0.917, 0.770, and 0.679, respectively, p < 0.0001). This study highlights how food components influence As metabolism to inform both personalized nutrition strategies and As exposure risk assessment.

Inadequate dietary fiber intake remains a global public health concern, and increasing fiber intake through staple foods has been proposed as a practical strategy. However, whether fiber incorporation interferes with mineral bioaccessibility remains unclear. In this study, the co-digestion of three commercial dietary fibers (wheat, oat, and soy) with 15 rice samples was systematically investigated using an in vitro gastrointestinal model, focusing on the bioaccessible concentrations of essential and toxic elements. The experimental design enabled simultaneous evaluation of interaction effects and net bioaccessible outcomes. The results revealed element-fiber specific interactions during co-digestion. Importantly, dietary fibers acted as significant mineral contributors, and their intrinsic mineral content primarily governed the net increases in bioaccessible essential elements. Bioaccessible concentrations during co-digestion closely matched the sum of individual digestions, indicating predominantly additive behavior. Co-digestion with wheat fiber increased the bioaccessible concentrations of both Ca and Mg to 2.7-fold compared to rice alone while maintaining Zn levels, whereas soy fiber resulted in the highest bioaccessible Ca (5.7-fold). Notably, none of the fibers increased the bioaccessible As or Cd. These findings suggest that the bioaccessible mineral in rice-fiber systems is largely determined by additive mineral contributions rather than generalized inhibitory interactions. This work highlights the importance of evaluating net bioaccessible intake in mixed-food systems and provides a scientific basis for improving mineral nutrition in rice-based diets through rational fiber selection.

Concerns are increasing about heavy metals in soil that harm human health and the integrity of ecosystems. Traditional treatment methods are insufficient to solve the problem. Therefore, new and sustainable methods should be investigated. Removal of heavy metals from the soil matrix through microbial and chemical treatments is a significant concern these days. Many chemical methods for soil improvement involve the use of lime, phosphate, zeolites, and chelating agents. The application of these amendments also changed the physical and chemical properties of the soil, leading to the formation of stable metal complexes or the precipitation of poorly soluble metals. Although chemical treatment is fast and effective, its long-term impact on the environment is worth considering. Alternatively, bacteria can metabolize the contaminated soil by removing the heavy metals, which is the basic concept of microbial remediation. This method of bioremediation is generally environmentally friendly because it employs natural processes and minimizes the need for external inputs. However, environmental conditions and other soil diseases can affect its performance. A combination of chemical and microbial remediation strategies can provide an integrated approach to remediating heavy metals in soil. The interaction between chemical treatments and microbial methods may offer additional solutions for effectively remediating heavy metal contamination in soil.

Ferrihydrite (Fh) as a soil active component is involved in the geochemical cycle and transformation of metal(loid) elements in microplastic (MP)-contaminated areas, posing a potential threat to human health, yet relevant information is still lacking. Herein, a 90-d microcosm incubation experiment was conducted to evaluate the effect of Fh on the geochemical fractionations and bioaccessibility of arsenic (As) and cadmium (Cd) in polyamide (PA)-contaminated soils, and PA-Fh interactions were elucidated through integrated assessment of iron (Fe) speciation extraction, spectroscopic characterization and theoretical calculation. Sequential extraction results demonstrated that PA-Fh coexistence decreased As and Cd environmental risks by converting their labile fractions into amorphous Fe/Al (oxyhydr)oxides and residual fractions, respectively. Meanwhile, soil As and Cd bioaccessibility decreased by 2.01–7.79% and 1.07–3.61% on day 90, respectively, and As(V) proportions in colon digests increased by 5.39–6.85%. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) confirmed an inhibitory effect on Fh crystallization transformation affected by PA-MPs. Bader charge analysis suggested that PA-MPs decreased the positive charge on Fh surface, as 0.043 electrons transferred to each Fe atom. Overall, the present study underscored the significance of Fe speciation and surface charge transformation in decreasing the bioaccessibility of metal(loid)s, promoting the environmentally sustainable remediation and risk management of areas co-contaminated by MPs and metal(loid)s.

Arsenic (As) contamination in paddy soils poses a serious threat to rice safety and human health. Environmentally persistent free radicals (EPFRs), as highly reactive species, have attracted increasing attention for their role in regulating As migration and transformation in soil systems. The quantitative understanding of how EPFRs influence As speciation and bioavailability in paddy soils remains limited, particularly regarding the role of EPFRs in stabilizing As within mineral and organic complexes. As a result, predicting the impacts of EPFRs on As bioavailability under specific agricultural management practices remains challenging. In this review, we systematically summarize recent advances in the characterization and formation mechanisms of EPFRs, key factors governing their generation and stability, and their effects on As speciation and bioavailability in paddy soils, emphasizing: (i) the oxidation of more mobile and toxic As(III) to less mobile As(V) via pathways such as EPFR-mediated electron transfer; (ii) the enhancement of As immobilization through iron plaque formation and mineral surface modification; (iii) the mediation of As bioavailability by influencing its speciation and partitioning. Building on this synthesis, we propose future research directions for elucidating the role of EPFRs in regulating As geochemical behavior. This review aims to advance the theoretical framework of EPFR-mediated interfacial reactions involving As in paddy soils and to provide a scientific basis for developing effective As pollution control strategies.

The gut microbiota plays a crucial role in arsenic (As) metabolism, yet the extent of As metabolism under gut dysbiosis and the gut's response to As exposure remain lacking. This study used a mouse model with gut dysbiosis induced by cefoperazone to explore As bioaccumulation, transformation, and excretion. By integrating absolute quantification methods, this study monitored the responses of gut microbiota, As biotransformation genes (ABGs), and gut metabolites in mice exposed to 1 and 10 mg/L As. Arsenic accumulation in the liver, spleen, heart, ileum, and blood was markedly decreased in gut dysbiosis mice exposed to 10 mg/L As. These mice also exhibited lower proportions of DMA(V) and As(V) in the liver compared with normal mice. A total of 17 ABGs were detected in the mouse gut, with a significant reduction in their absolute abundance in gut dysbiosis mice (e.g., arsC, arsH, and arsB genes). Consistently, gut dysbiosis mice had lower bacterial loads, particularly for Alloprevotella and Bacteroides, accompanied by the upregulation of "amino acids" and "fatty acid esters." Association analysis predicted several specific bacteria carrying ABGs, exemplified by Bacteroides carrying the arsC gene. Our findings provided further insights into As metabolism mediated by gut microbiota, for better understanding As-induced toxicity and disease risk.

Infancy is a critical window for the colonization of gut microbiome. However, xenobiotic impacts on gut microbiome development in early life remain poorly understood. Here, we recruit 146 mother-infant pairs and collect stool samples at 3, 6, and 12 months after delivery for amplicon sequencing (N = 353), metagenomics (N = 65), and metabolomics (N = 198). Trace elements in maternal hair samples (N = 119) affect diversity and composition of the infant gut microbiome. Shannon diversity in 3 month-old infants is correlated positively with selenium and negatively with copper, and relative abundance of Bifidobacterium increases under high exposure to aluminum and manganese. During the first year of life, infants and their paired mothers have distinct microbial diversity and composition, and their bacterial community structures gradually approach. here are 56 differential metabolites between the first and second visit and 515 differential metabolites between the second and third visit. The typical profile of antibiotic resistance genes (ARGs) significantly differs between infants and their mothers. High levels of copper and arsenic exposure may induce the enrichment of ARGs in the infant gut. Our findings highlight the dynamics of the gut microbiome, metabolites, and ARG profiles of mother-infant pairs after delivery, associated with prenatal exposure to trace elements.

The metals and metalloids (metal[loid]s) in the newly formed soil-slag mixing systems (SSMS), formed by the invasion of smelting slag into contaminated soils, may pose potential risks to environment and residents near the smelter sites. In this study, sequential extraction, leaching tests and in vitro bioaccessibility assays were conducted to assess the ecological and human health risk of metal(loid)s in SSMS. The results indicated that the contaminated soils and smelting slags were composed of more than 80 % silicate and oxide minerals, which served as the host phases for metal(loid)s in SSMS. Cd exhibited high mobility and availability, with its exchangeable fraction ranging from 0.15 % to 69.23 %. Leaching tests revealed high leachability and bioavailability of Cd, Mn and Zn. Moreover, metal(loid)s bioaccessibility varied amongst samples: 2.78-46.63 % of As, 11.87-95.25 % of Cd, 37.35-93.88 % of Mn, 1.97-87.84 % of Pb and 0-57.98 % of Zn. Risk assessment calculation results indicated potentially ecological risks posed by Cd, Mn, Pb, and Zn, and unfavorable carcinogenic risks associated with As and Cd, suggesting that remediation efforts were warranted. Overall, this study highlighted how the invasion of smelting slags can affect the accuracy of risk assessments, providing new guidance for risk control and environmental management at slag dumping sites.

Chromium (Cr) contamination in soil poses significant human health risks due to its toxicity and environmental persistence. In this study, the bioaccessibility of Cr from three aged agricultural soils was assessed using an in vitro (physiologically based extraction test, PBET) method. Simultaneously, single extraction methods (0.43 M HNO3 and EDTA) and in vivo (mouse model) bioassay were used to assess the health effects of Cr exposure. The results showed that Cr bioaccessibility in the gastric phase ranged from 0.7 % to 21.7 %, and was 1.3-1.8 folds higher in the small intestinal phase. Among the three soils, the weakly alkaline soil exhibited the highest bioaccessibility in both phases. Significant correlations (R2 = 0.74-0.95) were found between extractable Cr (%) and Cr bioaccessibility, particularly for 0.43 M HNO3. In vivo bioassays determined relative bioavailability (based on kidneys or liver), absolute bioavailability, and Cr concentration in tissues, revealing that Cr tended to be excreted rather than accumulated in tissues. Additionally, Cr exposure altered gut microbiota composition, notably increasing Lactobacillaceae while decreasing Muribaculaceae, Prevotellaceae and Rikenellaceae. This study highlighted that single extraction methods could predict in vitro bioaccessibility, which facilitates the rapid and accurate assessment of risks from oral intake of Cr-contaminated soils.

Brown rice and rice bran, which contain higher levels of minerals than commonly consumed milled rice, are often considered better for addressing widespread mineral deficiencies. However, their effectiveness in providing bioaccessible minerals remains unclear. This study aimed to compare the contributions of essential elements (Ca, Fe, Zn, Mg, Mn, Cu) to recommended nutrient intake (RNI) and the risk associated with As exposure via consumption of brown rice, milled rice, and rice bran, based on elements bioaccessibility. The results indicated that essential elements retention in milled rice was significantly lower compared to brown rice, with percentages ranging from 22.3 % for Mg to 77.6 % for Zn. Although rice bran contained a substantial proportion of essential elements, the extremely low bioaccessibility of essential elements in rice bran (almost < 5 % for Ca, Fe, Zn) rendered it ineffective for micronutrient supplementation. Furthermore, the intake of Ca and Fe from both brown and milled rice was also minimal (< 5 % of RNI). Notably, milled rice yielded about 2.7 times bioaccessible Zn than brown rice, making it a superior option for Zn-deficient populations, despite its contribution to the RNI of Zn remaining insufficient. By contrast, brown rice was more beneficial for Mg intake, accounting for nearly half of RNI; however, brown rice also presented 1.6 times bioaccessible As compared to milled rice. This study highlights the importance of incorporating elements bioaccessibility to systematically assess both the nutritional benefits and potential risks associated with different rice products, thereby providing valuable insights for developing rice consumption guidelines.

Food quality has gained increasing societal attention, shifting consumer demand for vegetables from quantity to quality. Organic fertilizers serve as valuable nutrient sources for improving soil fertility and crop quality, with common types including animal manure, plant residues, and kitchen waste; however, comparative studies on their effects remain limited. This study investigated nine organic fertilizer treatments from three waste sources and an inorganic control in a pot experiment with Chinese cabbage. Results demonstrated that the efficacy of organic fertilizers varied, emphasizing the importance of fertilizer ratios and types in shaping soil health and crop productivity. While most organic fertilizer treatments resulted in a lower fresh weight yield of Chinese Cabbage than inorganic fertilizers, the application of 0.1% plant residue organic fertilizer improved it by 29%. Kitchen waste organic fertilizer demonstrated good potential, enhancing vitamin C content by 54% and raising trace elements such as copper (1.3-fold). Moreover, organic fertilizers significantly altered soil microbial diversity, increasing bacterial OTUs and shifting community composition, particularly enhancing Proteobacteria and Ascomycota. Waste-derived organic fertilizers offer a promising approach for enhancing soil fertility, improving vegetable quality, and promoting microbial diversity, thereby providing a sustainable alternative to inorganic fertilizers.

Minerals control on the oral bioavailability of arsenic (As) in soil has been evidenced in human health risk assessments. However, little is known about the metabolism of soil mineral-associated As by human gut microbiota. This study evaluated the relative bioavailability (RBA) and bioaccessibility of As in As(V)-sorbed Aluminum (Al) oxides (α-Al2O3 and γ-Al2O3), affected by gut microbiota and Fe(III). The in vitro method yielded higher As bioaccessibility in the small intestinal phase of α-Al2O3 (30.3 %-54.8 %) and in the colon phase of γ-Al2O3 (29.7 %-45.6 %), respectively. In the presence of Fe, As release was decreased by14.5 %-48.1 % in the small intestine but increased by 37.5 %-86.3 % in the colon (p < 0.05). Speciation analysis revealed that gut microbiota reduced nearly half of the As(V) to As(III) in the colon digests, with up to 21.0 % of As(III) remaining in the solid phase. More than 92.0 % of Fe(III) in the colon digests was reduced to Fe(II), which would facilitate As reduction but inhibit methylation. A mouse bioassay was conducted to estimate As-RBA (21.3 %-58.8 %) in Al oxides, decreased by Fe(III) addition under high As exposure. Our findings provide new insights into the role of Al oxides in the risk assessment from inadvertent oral ingestion of As-contaminated soils.

Arsenic (As) contaminated soils have caused serious environmental threats. In this study, iron (Fe) and lanthanum (La)-loaded zeolites, with and without calcination (MZO/Fe-La and MZ/Fe-La), were developed to stabilize two As-contaminated soils. Water-soluble As, TCLP (toxicity characteristic leaching procedure) As, and available As in soils were investigated to evaluate the remediation efficiencies of the stabilizers. X-ray dispersion and infrared spectroscopy were used to interpret the mechanisms of soil As immobilization. After applying the modified-zeolite composites (1%--4%, w/w) to As-contaminated soils and incubating for 60 days, the most significant decreases in water-soluble As, TCLP As, and available As were achieved with a 4% addition for both soils: 97.0%, 96.4%, and 37.5% for soil #1, and 97.0%, 98.1%, and 30.2% for soil #2, respectively. Moreover, the amendments of MZ/Fe-La and MZO/Fe-La composites effectively convert non-specifically adsorbed As into specifically adsorbed As, amorphous oxides bound As and residual As, thus stabilizing soil As. This stabilization was attributed to the ligand exchange of hydroxyl groups (Fe-OH and La-OH loaded on zeolite after modification) with As, forming Fe/La-O-As complexes, which served as the central mechanism for soil As immobilization by the modified-zeolite composites. Collectively, this study advances green, sustainable approaches for the long-term, stable in-situ stabilization of arsenic-contaminated soils.

Exposure to arsenic (As) induces adverse effects on human health. Vitamins B1, B6, and C, as indispensable micronutrients for humans, have been proven to influence the metabolism and toxicity of ingested As. To determine the effect of vitamins on health risks associated with soil exposure, As bioaccessibility in 14 soil samples using four in vitro methods of IVG, PBET, SBRC, and UBM was measured with the addition of vitamins B1, B6, and C. With vitamins B1 and B6 addition, the gastric As bioaccessibility in 14 soil samples was reduced by 1.14-3.52 and 1.14-5.02 fold, respectively, and instead an increase in the intestinal bioaccessibility was presented in some cases. Vitamin C supplementation yielded higher As bioaccessibility in the gastric (1.13-13.02 fold) and small intestinal (1.21-33.35 fold) phases, respectively. As evidenced by the X-ray absorption near-edge spectroscopy (XANES) and Fourier transform infrared spectroscopy (FTIR) analysis, arsenic dissolution was promoted by Fe-As and hindered by the formation of Al-As fractions. Soil As dissolution in the simulated gastrointestinal tract was strongly influenced by soil minerals and ingested vitamins, due to the chelation of arsenic with vitamins and soil minerals such as Fe (hydr)oxides, and Fe(III) reductive dissolution to enhance As release by vitamin C as an iron reducer. These findings will expand the knowledge of health risks of exposure to As-contaminated soils and nutritional interventions aiming at the mitigation of As toxicity.

Soil is considered the primary source of heavy metals. Even at very low concentrations, chronic exposure to harmful heavy metal (arsenic) has a significant negative impact on human health. In this study, we evaluated the effect of nutrients including glucose, proteins, calcium and control (fasted condition) on soil arsenic (As) bioaccessibility by PBET (Physiologically Based Extraction Test) technique with SHIME (simulator of the human intestinal microbial ecosystem). As bioaccessibility of the NJY soil sample was 4.43 to 8.28%, 2.56 to 8.55% and 5.66 to 23.49% in gastric phase, intestine phase and colon phase respectively with different nutrients. CFI soil sample’s As bioaccessibility varied depending on the nutrients used, and was 5.78 to 23.86%, 2.32% to 12.54% and 1.06 to 13.85% in gastric phase, intestine phase and colon phase correspondingly. As bioaccessibility of the ZZH soil sample was 2.26 to 25.16%, 24.38% to 57.27% and 9.92 to 23.10% in gastric phase, intestine phase and colon phase with varying nutrients. The outcomes showed that, As bioaccessibility of the soil samples was greatly influenced with plant protein, animal protein, calcium and glucose in the three phases of the digestive system. Therefore, nutrients have a considerable effect on As bioaccessibility and assessment of human health risk.

Stabilization of arsenic-contaminated soils with ferrous sulfate has been reported in many studies, but there are few stabilization effects assessments simultaneously combined chemical extraction methods and in vitro methods, and further explored the corresponding alternative relationships. In this study, ferrous sulfate was added at FeAs molar ratio of 0, 5, 10 and 20 to stabilize As in 10 As spiked soils. Stabilization effects were assessed by 6 chemical extraction methods (toxicity characteristic leaching procedures (TCLP), HCl, diethylenetriamine pentaacetic acid (DTPA), CaCl2, CH3COONH4, (NH4)2SO4), and 4 in vitro methods (physiologically based extraction test (PBET), in vitro gastrointestinal method (IVG), Solubility Bioaccessibility Research Consortium (SBRC) method, and the Unified Bioaccessibility Research Group of Europe method (UBM)). The results showed that the HCl method provides the most conservative assessment results in non-calcareous soils, and in alkaline calcareous soils, (NH4)2SO4 method provides a more conservative assessment. In vitro methods provided significantly higher As concentrations than chemical extraction methods. The components of the simulated digestion solution as well as the parameters may have contributed to this result. The small intestinal phase of PBET and SBRC method produced the highest and lowest ranges of As concentrations, and in the range of 127-462 mg/kg and 68-222 mg/kg when the FeAs molar ratio was 5. So the small intestinal phase of PBET method may provide the most conservative assessment results, while the same phase of SBRC may underestimate the human health risks of As in stabilized soil by 51 %(at a FeAs molar ratio of 5). Spearman correlation analysis indicated that the small intestinal phase of PBET method correlated best with HCl method (correlation coefficient: 0.71). This study provides ideas for the assessment of stabilization efforts to ensure that stabilization meets ecological needs while also being less harmful to humans.

Arsenic (As)-contaminated soil poses great health risk to human mostly through inadvertent oral exposure. We investigated CaAl-layered double hydroxide (CaAl-LDH), a promising immobilising agent, for the remediation of As-contaminated Chinese soils. The effects on specific soil properties and As fractionation were analyzed, and changes in the health risk of soil As were accurately assessed by means of advanced in vivo mice model and in vitro PBET-SHIME model. Results showed that the application of CaAl-LDH significantly increased soil pH and concentration of Fe and Al oxides, and effectively converted active As fractions into the most stable residual fraction, guaranteeing long-term remediation stability. Based on in vivo test, As relative bioavailability was significantly reduced by 37.75%. Based on in vitro test, As bioaccessibility in small intestinal and colon phases was significantly reduced by 25.65% and 28.57%, respectively. Furthermore, As metabolism (reduction and methylation) by the gut microbiota inhabiting colon was clearly observed. After immobilisation with CaAl-LDH, the concentration of bioaccessible As(Ⅴ) in the colon fluid was significantly reduced by 61.91%, and organic As (least toxic MMA(V) and DMA(V)) became the main species, which further reduced the health risk of soil As. In summary, CaAl-LDH proved to be a feasible option for immobilisation remediation of As-contaminated soils, and considerable progress was made in relevant health risk assessment.