Multiple exposure pathways and urinary chromium in residents exposed to chromium

Long-term exposure to ambient PM2.5 and its components associated with hyperuricemia: Evidence from a rural cohort study

BACKGROUND

Current research lacks the association of PM2.5 and its components exposure with hyperuricemia (HUA). This study aimed to explore the association of PM2.5 and its components with HUA and to identify harmful components as well as susceptible populations.

METHODS

A total of 22,765 participants were derived from the Henan rural cohort. PM2.5 and its components data were obtained from the Tracking Air Pollution (TAP) dataset in China. Generalized linear models (GLM) were utilized to evaluate the association between PM2.5 and its components with HUA. Restricted cubic splines were employed to explore the dose-response relationship. Additionally, the weighted quantile sum (WQS) method was used to assess the joint effect of PM2.5 components and their relative contribution to HUA.

RESULTS

After adjusting for confounders, the odds ratios (OR) and 95 % confidence interval (CI) for per standard deviation (SD) increase in PM2.5, black carbon (BC), nitrate (NO3-), sulfate (SO42-), ammonium (NH4+), and organic matter (OM) were 1.81 (1.43, 2.30), 1.69 (1.38, 2.07), 1.70 (1.39, 2.08), 1.73 (1.40, 2.14), 1.67 (1.38, 2.04), and 1.58 (1.30, 1.92), respectively. Joint exposure to the five major chemical components also showed a positive association with the risk of HUA [1.09 (1.04, 1.15)], with NO3- contributing most significantly to the combined effect of the pollutant mixture. Additionally, exposure to PM2.5 and its components showed a nonlinear dose-response relationship with HUA (P nonlinear < 0.05). Stratified analysis indicated that men may be more susceptible to the effects of environmental PM2.5 and BC.

CONCLUSION

PM2.5 and its components increased the risk of HUA, with NO3- being the primary contributor, and men were more susceptible to the effects of PM2.5 and BC. The findings suggests that reducing PM2.5 levels could bring significant public health benefits.

Deciphering the impact of heavy metal mixed exposure on lipid metabolism using three statistical models

Lipid metabolism disorders pose a significant threat to human health. However, the relationship between heavy metal mixed exposure and lipid metabolism remains poorly understood. This study recruited 1717 residents living near a chromium factory in northeast China. The concentrations of blood Cr, Mn, Cd, Pb, V, and serum CHOL, TG, LDL and HDL levels were measured. Generalized linear model (GLM), quantile g-computation (Qg-comp), and Bayesian kernel machine regression (BKMR) were simultaneously employed to investigate the associations between heavy metal mixed exposure and lipid markers levels. GLM analysis revealed significant associations between blood Cr concentration and HDL (β =  -0.07; 95%CI:  -0.09,  -0.05), LDL (β =  -0.06; 95%CI:  -0.11,  -0.02), and CHOL (β = 0.07; 95%CI: 0.01, 0.12) levels. V concentration was positively associated with HDL (β = 0.12; 95%CI: 0.06, 0.18) and LDL (β = 0.17; 95%CI: 0.04, 0.30) levels. Qg-comp analysis indicated a negative association between heavy metal mixed exposure and HDL (β =  -0.040; 95%CI:  -0.073,  -0.006) level. BKMR model further confirmed the negative relationship between heavy metal mixed exposure and HDL, with the interaction between blood Cr (> 1.05 μg/L) and blood V (> 5.16 μg/L) contributing to decreased HDL levels. Our findings suggested that heavy metal mixed exposure had impacts on HDL and CHOL levels, and the Cr and V may mutually play a predominant role in the observed abnormal HDL levels.

Associations of mixed metal exposure with chronic kidney disease from NHANES 2011-2018

Metals have been proved to be one of risk factors for chronic kidney disease (CKD) and diabetes, but the effect of mixed metal co-exposure and potential interaction between metals are still unclear. We assessed the urine and whole blood levels of cadmium (Cd), manganese (Mn), lead (Pb), mercury (Hg), and renal function in 3080 adults from National Health and Nutrition Survey (NHANES) (2011-2018) to explore the effect of mixed metal exposure on CKD especially in people with type 2 diabetes mellitus (T2DM). Weighted quantile sum regression model and Bayesian Kernel Machine Regression model were used to evaluate the overall exposure impact of metal mixture and potential interaction between metals. The results showed that the exposure to mixed metals was significantly associated with an increased risk of CKD in blood glucose stratification, with the risk of CKD being 1.58 (1.26,1.99) times in urine and 1.67 (1.19,2.34) times in whole blood higher in individuals exposed to high concentrations of the metal mixture compared to those exposed to low concentrations. The effect of urine metal mixture was elevated magnitude in stratified analysis. There were interactions between urine Pb and Cd, Pb and Mn, Pb and Hg, Cd and Mn, Cd and Hg, and blood Pb and Hg, Mn and Cd, Mn and Pb, Mn and Hg on the risk of CKD in patients with T2DM and no significant interaction between metals was observed in non-diabetics. In summary, mixed metal exposure increased the risk of CKD in patients with T2DM, and there were complex interactions between metals. More in-depth studies are needed to explore the mechanism and demonstrate the causal relationship.

Associations of metals and metal mixtures with glucose homeostasis: A combined bibliometric and epidemiological study

This study employs a combination of bibliometric and epidemiological methodologies to investigate the relationship between metal exposure and glucose homeostasis. The bibliometric analysis quantitatively assessed this field, focusing on study design, predominant metals, analytical techniques, and citation trends. Furthermore, we analyzed cross-sectional data from Beijing, examining the associations between 14 blood metals and 6 glucose homeostasis markers using generalized linear models (GLM). Key metals were identified using LASSO-PIPs criteria, and Bayesian kernel machine regression (BKMR) was applied to assess metal mixtures, introducing an "Overall Positive/Negative Effect" concept for deeper analysis. Our findings reveal an increasing research interest, particularly in selenium, zinc, cadmium, lead, and manganese. Urine (27.6%), serum (19.0%), and whole blood (19.0%) were the primary sample types, with cross-sectional studies (49.5%) as the dominant design. Epidemiologically, significant associations were found between 9 metals-cobalt, copper, lithium, manganese, nickel, lead, selenium, vanadium, zinc-and glucose homeostasis. Notably, positive-metal mixtures exhibited a significant overall positive effect on insulin levels, and notable interactions involving nickel were identified. These finding not only map the knowledge landscape of research in this domain but also introduces a novel perspective on the analysis strategies for metal mixtures.

Associations between inhalation of typical volatile and semi-volatile organic compounds in e-waste dismantling workers with liver function damage

Studies in cell culture and animal models suggest hepatotoxicity of some volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), however, their effects in human populations under real exposure conditions have never been clarified. In this cross-sectional study, 224 participants, 38 e-waste dismantling workers and 186 subjects residing near to the dismantling sites in southern China, were evaluated for personal inhalational exposure to 72 VOCs and 91 SVOCs according to site-specific atmospheric chemical concentrations and personal exposure time. Additionally, their serum samples were subjected to liver function tests (LFTs), including total protein (TP), albumin (ALB), globulin (GLB), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), and bilirubin. Linear regression analysis of the VOC/SVOC levels against the LFTs results indicated that VOC exposure was negatively associated with the TP, ALB, GLB levels (indicating liver-specific protein synthesis functions), while positively associated with AST, ALT, GGT activities (marking liver damage). Somehow, SVOC exposure appeared to be positively associated with not only AST and ALT but also TP and ALB. These findings were supported by the quantile g-computation analysis and confirmed in the Bayesian kernel machine regression model. This study indicates that simultaneous inhalation of VOCs and SVOCs may impair human liver functions.

Threshold effect of urinary chromium on kidney function biomarkers: Evidence from a repeated-measures study

Chronic kidney disease (CKD) is a public health concern worldwide, and chromium exposure may be a risk factor due to its potential nephrotoxicity. However, research on the association between chromium exposure and kidney function especially the potential threshold effect of chromium exposure is limited. A repeated-measures study involving 183 adults (641 observations) was conducted from 2017 to 2021 in Jinzhou, China. Urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) were measured as kidney function biomarkers. Generalized mixed models and two-piecewise linear spline mixed models were used to assess the dose-response relationship and potential threshold effect of chromium on kidney function, respectively. Temporal analysis was conducted by the latent process mixed model to depict the longitudinal change of kidney function over age. Urinary chromium was associated with CKD (odds ratio [OR] = 1.29; 95 % confidence interval [CI], 6.41, 14.06) and UACR (Percent change = 10.16 %; 95 % CI, 6.41 %, 14.06 %), and we did not find significant association between urinary chromium and eGFR (Percent change = 0.06 %; 95 % CI, -0.80 %, 0.95 %). The threshold analyses suggested the existence of threshold effects of urinary chromium, with inflection points at 2.74 μg/L for UACR and 3.95 μg/L for eGFR. Furthermore, we found that chromium exposure exhibited stronger kidney damage over age. Our study provided evidence for the threshold effects of chromium exposure on kidney function biomarkers and the heightened nephrotoxicity of chromium in older adults. More attention should be paid to the supervision of chromium exposure concentrations for preventing kidney damage, especially in older adults.

Skin aging associated with chromium among rural housewives in northern China

Previous studies have found associations between chromium exposure and skin damage. However, few studies have focused on both chromium and skin aging. This study aimed to assess the degree of skin aging symptoms and estimate the relationship between hair chromium and skin aging among rural housewives. We recruited 405 subjects in Shanxi Province of northern China and analyzed 397 eligible hair samples with inductively coupled plasma-mass spectrometry (ICP-MS). The subjects' skin aging symptoms were assessed with SCINEXA™ (SCore of INtrinsic and EXtrinsic skin Aging). After adjusting for age and other important covariates, the regression results showed more severe skin aging symptoms in women with a higher level of hair chromium and presented an increasing linear trend. Vegetables, fruits, and beans might be a source of chromium exposure. We concluded that skin aging might be positively associated with hair chromium. It is necessary to take measures to reduce chromium exposure to prevent skin aging.

Effect of nanobiochar (nBC) on morpho-physio-biochemical responses of black cumin (Nigella sativa L.) in Cr-spiked soil

Chromium is a highly toxic heavy metal. High concentrations of Cr (III) can affect metabolic processes in plants, resulting in different morphological, physiological, and biochemical defects. Agricultural practices such as sewage irrigation, over-fertilization, and sewage sludge application contribute significantly to Cr contamination. It can reduce the growth of plants by affecting the activity of antioxidant enzymes. The materials in nano form play an important role in nano-remediation and heavy metals absorption due to their high surface area and micropores. This research was conducted to study the potential of foliar application of nanobiochar/nBC (100 mg/L^-1 and 150 mg/L^-1) for mitigation of Cr (III) stress (200 mg/kg and 300 mg/kg) in black cumin (Nigella sativa) plants. The results showed that increased Cr stress (300 mg/kg) decreased the plant growth parameters, chlorophyll content, total soluble sugars, and proteins. However, increased the level of hydrogen peroxide (H₂O₂) and malondialdehyde acetate (MDA) as a result of the activity of antioxidant enzymes (Catalase, Superoxide dismutase, peroxidase dismutase, and ascorbic peroxidase) increased in Nigella sativa seedlings. Foliar application of the nBC (100 mg/L^-1) increased plant growth parameters, chlorophyll content, and osmoprotectants, while decreasing the levels of oxidative stress markers (H₂O₂ and MDA). Furthermore, with the application of nBC, the antioxidant enzyme activity considerably improved. Improved antioxidant activity shows that nBC helped to decrease oxidative stress, which in return improved the growth of Nigella sativa seedlings. Overall, present study findings concluded that foliar application of nBC in Nigella sativa seedlings improved growth, chlorophyll, and antioxidant enzymes. The nBC treatment of 100 mg/L^-1 showed better results compared to 150 mg/L^-1 under chromium stress.

Physiological and transcriptomic evidence of antioxidative system and ion transport in chromium detoxification in germinating seedlings of soybean

Chromium (Cr) toxicity impairs the productivity of crops and is a major threat to food security worldwide. However, the effect of Cr toxicity on seed germination and transcriptome of germinating seedlings of soybean crop has not been fully explored. In this study, two Cr-tolerant lines (J82, S125) and two Cr-sensitive ones (LD1, RL) were screened out of twenty-one soybean (Glycine max L.) genotypes based on seed germination rate, seed germinative energy, seed germination index, and growth of germinating seedlings under 50 mg L^-1 Cr treatment. We found that Cr stress inhibits the growth of soybean seed germinating seedlings due to the Cr-induced overaccumulation of reactive oxygen species (ROS). Significantly different levels of element contents, antioxidant enzyme activities, malondialdehyde content were observed in the four soybean genotypes with contrasting Cr tolerance. Further, a total of 13,777 differentially expressed genes (DEGs) were identified in transcriptomic sequencing and 1298 DEGs in six gene modules were found highly correlated with the physiological traits by weighted correlation network analysis (WGCNA) analysis. The DEGs encoding antioxidant enzymes, transcription factors, and ion transporters are proposed to confer Cr tolerance in soybean germinating seedlings by reducing the uptake and translocation of Cr, decreasing the level of ROS, and keeping the osmotic balance in soybean germinating seedings. In conclusion, our study provided a molecular regulation network on soybean Cr tolerance at seed germinating stage and identified candidate genes for molecular breeding of low Cr accumulation soybean cultivars.

Adverse Human Health Effects of Chromium by Exposure Route: A Comprehensive Review Based on Toxicogenomic Approach

Heavy metals are defined as metals with relatively high density and atomic weight, and their various applications have raised serious concerns about the environmental impacts and potential human health effects. Chromium is an important heavy metal that is involved in biological metabolism, but Cr exposure can induce a severe impact on occupational workers or public health. In this study, we explore the toxic effects of Cr exposure through three exposure routes: dermal contact, inhalation, and ingestion. We propose the underlying toxicity mechanisms of Cr exposure based on transcriptomic data and various bioinformatic tools. Our study provides a comprehensive understanding of the toxicity mechanisms of different Cr exposure routes by diverse bioinformatics analyses.

Trace elements and Alzheimer dementia in population-based studies: A bibliometric and meta-analysis

Alterations in the concentrations of trace elements may play a vital role in Alzheimer dementia progression. However, previous research results are inconsistent, and there is still a lack of review on the relationship between all the studied-trace elements and AD from various perspectives of population-based studies. In this study, we systematically reviewed previous population-based studies and identified the altered trace elements in AD patients. We searched the Web of Science Core Collection, PubMed, and Scopus database, and ultimately included 73 articles. A bibliometric analysis was conducted to explore the evolution of the field from an epidemiological perspective. Bibliometric data such as trace elements, biological materials, detection methods, cognitive tests, co-occurrence and co-citation statistics are all analyzed and presented in a quantitative manner. The 73 included studies analyzed 39 trace elements in total. In a further meta-analysis, standardized mean differences (SMDs) of 13 elements were calculated to evaluate their altered in AD patients, including copper, iron, zinc, selenium, manganese, lead, aluminum, cadmium, chromium, arsenic, mercury, cobalt, and manganese. We identified four trace elements-copper (serum), iron (plasma), zinc (hair), and selenium (plasma)-altered in AD patients, with SMDs of 0.37 (95% confidence interval [CI]: 0.10, 0.65), -0.68 (95% CI: -1.34, -0.02), -0.35 (95% CI: -0.62, -0.08), and -0.61 (95% CI: -0.97, -0.25), respectively. Finally, we formed a database of various trace element levels in AD patients and healthy controls. Our study can help future researchers gain a comprehensive understanding of the advancements in the field, and our results provide comprehensive population-based data for future research.

Independent, combine and interactive effects of heavy metal exposure on dyslipidemia biomarkers: A cross-sectional study in northeastern China

Dyslipidemia is a common disease in the older population and represents a considerable disease burden worldwide. Epidemiological and experimental studies have indicated associations between heavy metal exposure and dyslipidemia; few studies have investigated the effects of heavy metal mixture and interactions between metals on dyslipidemia. We recruited 1121 participants living in heavy metal-contaminated and control areas in northeast China from a cross-sectional survey (2017-2019). Urinary metals including chromium (Cr), cadmium (Cd), lead (Pb), and manganese (Mn) and dyslipidemia biomarkers, namely triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels, were measured. The generalized linear model (GLM) was used to explore the association of a single metal with dyslipidemia biomarkers. Bayesian kernel machine regression (BKMR) and multivariable linear regression were performed to explore the overall effect of metal mixture and the interaction between metals on dyslipidemia. Heavy metal mixture was positively associated with LDL-C, TC, and TG and negatively with HDL-C. In multivariable linear regression, Pb and Cd exhibited a synergistic association with LDL-C in the participants without hyperlipemia. Mn-Cd and Pb-Cr also showed a synergistic association with increasing the level of LDL-C in subjects without hyperlipemia. Cd-Cr showed an antagonistic association with HDL-C, respectively. Cr-Mn exhibited an antagonistic association with decreased HDL-C and TG levels. No significant interaction was noted among the three metals. Our study indicated that exposure to heavy metals is associated with dyslipidemia biomarkers and the presence of potential synergistic or antagonistic interactions between the heavy metals.

Association of environmental exposure to chromium with differential DNA methylation: An epigenome-wide study

Introduction: Previous studies have reported that chromium (Cr)-induced epigenetic alterations and DNA methylation play a vital role in the pathogenesis of diseases induced by chromium exposure. Epigenomic analyses have been limited and mainly focused on occupational chromium exposure; their findings are not generalizable to populations with environmental Cr exposure. Methods: We identified the differential methylation of genes and regions to elucidate the mechanisms of toxicity related to environmental chromium exposure. DNA methylation was measured in blood samples collected from individuals in Cr-contaminated (n = 10) and unexposed areas (n = 10) by using the Illumina Infinium HumanMethylation850K array. To evaluate the relationship between chromium levels in urine and CpG methylation at 850 thousand sites, we investigated differentially methylated positions (DMPs) and differentially methylated regions (DMRs) by using linear models and DMRcate method, respectively. The model was adjusted for biologically relevant variables and estimated cell-type compositions. Results: At the epigenome-wide level, we identified five CpGs [cg20690919 (p _{FDR =}0.006), cg00704664 (p _{FDR =}0.024), cg10809143 (p _{FDR =}0.043), cg27057652 (p _{FDR =}0.047), cg05390480 (p _{FDR =}0.024)] and one DMR (chr17: 19,648,718-19,648,972), annotated to ALDH3A1 genes (p < 0.05) as being significantly associated with log₂ transformed urinary chromium levels. Discussion: Environmental chromium exposure is associated with DNA methylation, and the significant DMPs and DMR being annotated to cause DNA damage and genomic instability were found in this work. Research involving larger samples is required to further explore the epigenetic effect of environmental chromium exposure on health outcomes through DNA methylation.

Do urinary metals associate with the homeostasis of inflammatory mediators? Results from the perspective of inflammatory signaling in middle-aged and older adults

OBJECTIVE

We aimed to investigate whether urinary metal mixtures are associated with the homeostasis of inflammatory mediators in middle-aged and older adults.

METHODS

A four-visit repeated-measures study was conducted with 98 middle-aged and older adults from five communities in Beijing, China. Only one person was lost to follow-up at the third visit. Ultimately, 391 observations were included in the analysis. The urinary concentrations of 10 metals were measured at each visit using inductively coupled plasma mass spectrometry (ICP-MS) with a limit of detection (LOD) ranging from 0.002 to 0.173 µg/L, and the detection rates were all above 84%. Similarly, 14 serum inflammatory mediators were measured using a Beckman Coulter analyzer and the Bio-Plex MAGPIX system. A linear mixed model (LMM), LMM with least absolute shrinkage and selection operator regularization (LMMLASSO), and Bayesian kernel machine regression (BKMR) were adopted to explore the effects of urinary metal mixtures on inflammatory mediators.

RESULTS

In LMM, a two-fold increase in urinary cesium (Cs) and chromium (Cr) was statistically associated with -35.22% (95% confidence interval [CI]: -53.17, -10.40) changes in interleukin 6 (IL-6) and -11.13% (95 %CI: -20.67, -0.44) in IL-8. Urinary copper (Cu) and selenium (Se) was statistically associated with IL-6 (88.10%, 95%CI: 34.92, 162.24) and tumor necrosis factor-alpha (TNF-α) (22.32%, 95%CI: 3.28, 44.12), respectively. Similar results were observed for the LMMLASSO and BKMR. Furthermore, Cr, Cs, Cu, and Se were significantly associated with other inflammatory regulatory network mediators. For example, urinary Cs was statistically associated with endothelin-1, and Cr was statistically associated with endothelin-1 and intercellular adhesion molecule 1 (ICAM-1). Finally, the interaction effects of Cu with various metals on inflammatory mediators were observed.

CONCLUSION

Our findings suggest that Cr, Cs, Cu, and Se may disrupt the homeostasis of inflammatory mediators, providing insight into the potential pathophysiological mechanisms of metal mixtures and chronic diseases.

Source apportionment and health risk assessment for potentially toxic elements in size-fractionated road dust in Busan Metropolitan City, Korea

Potentially toxic elements' (PTEs; V, Cr, Co, Ni, Cu, Zn, As, Cd, Sb, Pb, and Hg) pollution level was investigated in size-fractionated road dust in Busan Metropolitan City. Health risks to humans (adult and children) were also evaluated in fine particle fraction (< 63 μm) of road dust. PTE concentrations in the fine particles (< 63 μm) were ranked as follows (unit: mg/kg): Zn (2511) > Cu (559) > Cr (531) > Pb (385) > Ni (139) > V (83.8) > Sb (31.6) > Co (21.6) > As (17.2) > Cd (4.1) > Hg (0.38). The PTE concentrations in fine particles (< 63 μm) were significantly higher than those in coarse particles except for V, Co, and As. The mean PTE loadings of fine particle fraction (< 63 μm; 233 mg/m2) in road dust were up to 4.5 times higher than other particle fractions. Igeo values of Sb were higher than 5 except for > 1000-μm fraction, indicating extremely polluted status. PCA results and elemental ratios indicated that most of the PTEs in road dust were derived from non-exhaust traffic-related sources such as brake pads and tires. Cr, Pb, and Sb had higher HI values than other metals for both adults and children. Sampling sites of heavy traffic and industrial areas showed that the carcinogenic risk exceeded the maximum threshold level (10 - 4). Especially in children, the mean carcinogenic risk (ingestion pathway) of As (6.8 × 10 - 4) Cd (2.0 × 10 - 4), and Ni (4.1 × 10 - 4) exceeded the maximum threshold level, indicating that continuous exposure to road dust may pose a high cancer risk to children. Therefore, continuous monitoring and management of these metals are needed to protect human health and the urban environment.

Determinants of carbon load in airway macrophages in pregnant women

The airway macrophages carbon loading (AMCL) has been suggested to be a biomarker of the long-term exposure to air pollution; however, to date no study has characterized AMCL for the pregnancy period. Therefore, this study aimed to assess the determinants of AMCL during pregnancy in Iran, a middle-income country. This study was based on a sample of 234 pregnant women with term and normal vaginal delivery who were residing in Sabzevar, Iran (2019). We characterized 35 potential determinants of personal exposure to air pollution for each participant, including six personal, nine indoor, and 20 home-outdoor factors. We applied Deletion/Substitution/Addition algorithm to identify the most relevant determinants that could predict AMCL levels. The median (IQR) of AMCL level was 0.12 (0.30) μm² with a successful sputum induction in 82.9% (194) of participants. Ambient residential PM_2.5 levels were positively associated with higher AMCL levels. On the other hand, increased residential distance to the traffic lights, squares and ring-roads, the duration of opening window per day, and opening window during cooking were inversely associated with AMCL levels. Our findings provide novel insights on the different personal, indoor, and outdoor determinants of personal exposure to air pollution during pregnancy in a middle-income country.

Analysis of Threshold Effect of Urinary Heavy Metal Elements on the High Prevalence of Nephrolithiasis in Men

Exposure to heavy metals in the environment exerts serious effects on kidney health. However, the effects of joint exposure on the kidneys have been rarely studied, particularly in non-occupational exposure high-risk populations. This study provided a reference threshold range of heavy metals in urine and explored the effect of joint exposure on nephrolithiasis in men. The data were obtained from the China Multi-Ethnic Cohort database, and 1502 men were included in the study. A two-piece-wise regression model was used to assess the dose-response relationship between heavy metal exposure and nephrolithiasis. The least absolute shrinkage and selection operator regression model was used to calculate the score of joint exposure to heavy metals. The threshold effect analysis revealed a linear relationship between the concentration of arsenic (As) in the urine and the prevalence of nephrolithiasis, whereas a nonlinear relationship was observed with cadmium (Cd), chromium (Cr), mercury (Hg), and lead (Pb). In addition, As, Cd, Cr, Hg, and Pb may significantly affect the joint exposure effect. Moreover, the final risk of nephrolithiasis increased by 123% (P for trend < 0.001). This study found a threshold relationship between heavy metals (Cd, Cr, Hg, Pb) in male urine and the occurrence of nephrolithiasis. Joint exposure to heavy metals in urine caused a high-risk effect on nephrolithiasis. The study provided a reference threshold value of related studies and indicated that environmental pollution caused by heavy metals should be reduced.

Chromium biogeochemical behaviour in soil-plant systems and remediation strategies: A critical review

Chromium (Cr) is a toxic heavy metal that is heavily discharged into the soil environment due to its widespread use and mining. High Cr levels may pose toxic hazards to plants, animals and humans, and thus have attracted global attention. Recently, much progress has been made in elucidating the mechanisms of Cr uptake, transport and accumulation in soil-plant systems, aiming to reduce the toxicity and ecological risk of Cr in soil; however, these topics have not been critically reviewed and summarised to date. Accordingly, based on available data-especially from the last five years (2017-2021)-this review traces a plausible link among Cr sources, levels, chemical forms, and phytoavailability in soil; Cr accumulation and translocation in plants; and Cr phytotoxicity and detoxification in plants. Additionally, given the toxicity and hazard posed by Cr(VI) in soils and the application of reductant materials to reduce Cr(VI) to Cr(III) for the remediation of Cr(VI)-contaminated soils, the reduction and immobilisation mechanisms by organic and inorganic reductants are summarised. Finally, some priority research challenges concerning the biogeochemical behaviour of Cr in soil-plant systems are highlighted, as well as the environmental impacts resulting from the application of reductive materials and potential research prospects.

Negatively interactive effect of chromium and cadmium on obesity: Evidence from adults living near ferrochromium factory

BACKGROUND

Researchers have reported that chromium (Cr) exposure may be associated with metabolism of glucose and lipids in residents living in a long-term Cr polluted area. Previous statistical analysis is mainly focused on individual chromium exposure. Furtherly, we aim to investigated the independent, combined, and interaction effects of the co-exposure of urine Cr (UCr) with cadmium (UCd), lead (UPb) and manganese (UMn) on body mass index (BMI), waist circumference, and the risk of overweight and abdominal obesity.

METHOD

We enrolled 1187 participants from annual surveys between 2017 and 2019. Heavy metal concentrations in urine were standardized using covariate-adjusted urine creatinine levels. Multiple linear/logistic regression models were applied to measure the single effect of urine heavy metal concentration on the outcomes. The quantile-based g-computation (g-comp) model was used to evaluate the combined effect of metal mixture on the outcomes and to compare the contribution of each metal. Both additive and multiplicative interactions were measured for UCr with UCd, UPb, UMn on the outcomes. Analysis was performed on the overall population and stratified by smoking habit.

RESULTS

For the overall study population, UCr was positively associated with BMI (p trend = 0.023) and waist circumference (p trend = 0.018). For smoking participants, the g-comp model demonstrated that the metal mixture was negatively associated with BMI, with UCr and UCd contributing the most in the positive and negative direction. A negative additive interaction was observed between UCr and UCd on BMI and abdominal obesity. We did not observe a significant interaction effect of UCr with UPb or UMn.

CONCLUSION

Our study indicated that Cr and Cd exposure may be associated with BMI and waist circumference, with combined and interaction effects of the heavy metals noted. Further epidemiological and experimental researches could simultaneously consider single and complex mixed exposure to verify the findings and biological mechanisms.

Association between urine metals and liver function biomarkers in Northeast China: A cross-sectional study

BACKGROUND

After heavy metals enter the body, they affect a variety of organs, particularly the main metabolic organ, the liver. Moreover, people are more likely to be exposed to multiple metals than to a single metal. We explored the associations between exposure to a heavy metal mixture and liver function biomarkers.

METHODS

This study involved 1171 residents living in areas with or without heavy metal exposure in northeast China. Urine concentrations of chromium (Cr), cadmium (Cd), lead (Pb), and manganese (Mn) were measured. Total protein (TP), albumin (ALB), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were used as biomarkers of liver function. A generalized linear model (GLM), quantile g-computation, and Bayesian kernel machine regression (BKMR) were used to explore the associations between the four metals and liver function.

RESULTS

GLM analysis revealed that Cr level was negatively associated with TP (β = - 0.57; 95% CI: - 0.89, - 0.26) and ALB (β = - 0.27; 95% CI: - 0.47, - 0.07) levels, and Cd level was positively associated with AST (β = 1.04; 95% CI: 0.43, 1.65) and ALT (β = 0.94; 95% CI: 0.08, 1.79) levels. ALB (β = 0.26; 95% CI: 0.10, 0.41) and ALT (β = 0.52; 95% CI: 0.02, 1.02) levels were positively associated with urine Mn concentration. The quantile g-computation indicated that exposure to a mixture of the four metals was significantly associated with TP (β = - 0.56; 95% CI: - 0.94, - 0.18) and ALT (β = 0.84; 95% CI: 0.04, 1.63) levels. Among the metals, Cr had the strongest effect on TP and Cd had that on AST. The BKMR model indicated that mixed metal exposure was negatively associated with TP and ALB levels and positively associated with ALT and AST levels.

CONCLUSION

Exposure to mixtures of heavy metals may influence liver function. Cr and Cd may be the largest contributors.

Fe3O4–SiO2–graphene oxide–amino acid ionic liquid magnetic solid-phase extraction combined with inductively coupled plasma optical emission spectrometry for speciation of Cr(iii) and Cr(vi) in environmental water

This developed method, based on the combination of functionalized Fe3O4–SiO2–GO–AAIL and ICP-OES, is capable of remarkable selectivity towards Cr(iii).

Health Risk Assessment of Metals via Multi-Source Oral Exposure for Children Living in Areas with Intense Electronic Manufacturing Activities

Oral ingestion is the predominant pathway of metal(loid)s exposure. In this study, the health risks of typical metal(loid)s (including Mn, As, Cr, Cd, and Pb) via multi-source, oral pathways for children aged 3-12 years, living in an area of China dominated by the electronic manufacturing industry, were studied based on the field sampling of duplicated diet, soil, and drinking water. Child-specific ingestion parameters were measured (except the soil ingestion rates, which were from a previous study of the same population), and a Monte Carlo method was applied to determine the uncertainty of the risk assessment. It was observed that children living in such environments were at risk of metal(loid)s exposure, with the accumulative carcinogenic risk exceeding the maximum acceptable level. Food intake was identified to be the primary exposure pathway. Moreover, Pb and Cr were the major risk elements to local children's health. Compared with primary school students, kindergarten children experienced a higher risk. This study highlights that high attention should be paid to children living in suburban areas dominated by the electronic manufacturing industry, and that priority should be given to studies on metal(loid)s exposure deriving from different types of food and their corresponding bioavailability, in order to further discern the precise risk sources to protect children's health.

Effective Removal of Cr(VI) from Wastewater Using Biochar Derived from Walnut Shell

Heavy metals are the major concern of the modern age. Among the heavy metals, chromium (Cr(VI)) is regarded as a highly toxic heavy metal released largely from leather tanning operations. To remove such high concentrations of Cr(VI), an advanced method is required urgently. Thus, biosorption using biochar, which is an organic material produced from various sources such as walnut shell, can be applied successfully for Cr(VI) abatement. The major objectives of this experiment were the remediation of the Cr(VI) heavy metal using walnut shell biochar and checking of the effect of pH, biochar dosage, Cr level, and shaking time. Remediation of Cr(VI) using walnut shell biochar was proved to be effective and removed the maximum concentration of Cr(VI) up to 93% at pH 5.5, 2 h agitation time, and the biochar amount of 1.1 g L⁻¹ from an aqueous solution. Equilibrium modeling demonstrated that the chemisorption process was involved in adsorption of Cr(VI). The surface of the biochar was porous and provided numerous sites for Cr(VI) attachment, which was also confirmed by the presence of Cr(VI) onto the biochar after adsorption. Hence, the use of walnut shell biochar was highly effective as a sorbent, which could conveniently be applied to small-scale as well as large-scale levels.

Systematic review of biomonitoring data on occupational exposure to hexavalent chromium

Occupational exposure to hexavalent chromium (Cr(VI)) can cause serious adverse health effects such as lung cancer and irritation of the skin and airways. Although assessment of chromium (Cr) in urine is not specific for Cr(VI) exposure, the total amount of Cr in urine is the most used marker of exposure for biomonitoring of Cr(VI). The purpose of this systematic review was fourfold: (1) to assess current and recent biomonitoring levels in subjects occupationally exposed to Cr(VI), with a focus on urinary Cr levels at the end of a working week, (2) to identify variables influencing these biomonitoring levels, (3) to identify how urinary Cr levels correlate with other Cr(VI) exposure markers and (4) to identify gaps in the current research. To address these purposes, unpublished and published biomonitoring data were consulted: (i) unpublished biomonitoring data comprised urinary Cr levels (n = 3799) of workers from different industries in Belgium collected during 1998-2018, in combination with expert scores indicating jobs with Cr exposure and (ii) published biomonitoring data was extracted by conducting a systematic literature review. A linear mixed effect model was applied on the unpublished biomonitoring data, showing a decreasing time trend of 30% in urinary Cr levels. Considering the observed decreasing time trend, only articles published between January 1, 2010 and September 30, 2020 were included in the systematic literature search to assess current and recent biomonitoring levels. Twenty-five studies focusing on human biomonitoring of exposure to Cr(VI) in occupational settings were included. Overall, the results showed a decreasing time trend in urinary Cr levels and the need for more specific Cr(VI) biomarkers. Furthermore, this review indicated the importance of improved working conditions, efficient use of personal protective equipment, better exposure control and increased risk awareness to reduce Cr levels in biological matrices. Further investigation of the contribution of the different exposure routes is needed, so that better guidance on the use of control measures can be provided. In addition, this review support the call for more harmonization of human biomonitoring.

One-minute highly selective Cr(VI) determination at ultra-trace levels: An ICP-MS method based on the on-line trapping of Cr(III)

An analytical method derived from the coupling of frontal chromatography (FC) with Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) is proposed for the fast determination of Cr(VI) ultra-traces. The insertion of a short, homemade column filled with a strong cationic exchange resin in the flow-path of a commercial ICP-MS allows on-line trapping of cationic Cr(III) and elution of anionic Cr(VI). As a result, only the Cr(VI) front reaches the detector. This separation mechanism enables the highly selective quantification of Cr(VI) ultra-traces (LOD = 0.026 µg/kg - defined as 3 s of 10 replicated measurements of a 0.050 µg/kg solution) over a wide linearity range (tested up to 1024 µg/kg), even in the presence of Cr(III) concentration as high as 50 mg/kg. Key advantages of the proposed method are the extremely short analysis time (one minute), together with the simplicity and cost-effectiveness of the modifications applied over a commercial ICP-MS instrumental configuration. No time- or chemical-consuming pretreatments are needed: it is only necessary to acidify the sample prior Cr(VI) determination, as normally performed for common ICP-MS analysis. The applicability of the method was demonstrated over mineral water samples and toy migration solutions.

Migration and fate of characteristic pollutants migration from an abandoned tannery in soil and groundwater by experiment and numerical simulation

The tannery industry is an integral part of economic development in many developing countries, and the environmental pollution caused by the tannery industry cannot be ignored. In this study, soil and groundwater samples at different depths were collected from an abandoned tannery to investigate the temporal and spatial distribution of characteristic pollutants produced by tanning. The concentrations of Cr, Cl, F and NH₄⁺-N in the soil from the sludge temporary storage area were higher than those from the liming and unhairing workshop, chrome tanning workshop, wastewater outlet, and around wastewater pond. The concentration of Cr(VI) in all sampling sites was below the detection limit. The main species of Cr in the groundwater were Cr(NH₃)₆Cl²⁺ and CrO₄^2- based on the simulation of Visual MINTEQ. The saturation index was negative and changed with time indicating that Cr existed in the dissolved phase. The proportion of Cr(VI) to total Cr was negatively correlated with the saturation index in village 1 and village 3. The simulation results from Visual MODFLOW and MT3DMS showed that the migration of Cr, NH₄⁺-N, Cl^- and F^- mainly occurred in the Quaternary system. The coverage of the pollution plume of pollutants in villages 1 and 3 was as follows: Cr > NH₄⁺-N > Cl^- > F^-. Two decay rate calculation methods of pollutants with migration time and distance were put forward to provide a basis for the actual investigation of the pollution migration scope and time determination.

The link between deacetylation and hepatotoxicity induced by exposure to hexavalent chromium

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Cr(VI) can induce inflammatory, oxidative stress, and apoptosis in rat liver.

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Cr(VI) induces inflammatory response in the liver by inhibiting deacetylation.

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Oxidative stress caused by Cr(VI) is related to the inhibition of deacetylation.

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Cr(VI) aggravates hepatocyte apoptosis by inhibiting deacetylation in rats.

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Cr(VI) induces liver injury via inhibition of the deacetylation of Sirt1.

Introduction

Hexavalent chromium (Cr(VI)), one of the toxic heavy metals, poses a serious threat to human and animal health. Protein acetylation regulates the structure and function of most proteins in a variety of ways. However, the hepatotoxicity of Cr(VI) and whether it is related to deacetylation remains largely unknown.

Objectives

We aimed to explore the link between the deacetylation of silent information regulator two ortholog 1 (Sirt1) and hepatotoxicity induced by Cr(VI) exposure, and to better clarify the biological mechanism of liver injury induced by Cr(VI).

Methods

We established a model of liver injury of K₂Cr₂O₇ by injecting rats intraperitoneally for 35 days continuously and adding resveratrol (Res) to further explore the link between deacetylation and hepatotoxicity.

Results

The results revealed that Cr(VI) induced inflammatory response and apoptosis in hepatocytes. Furthermore, Cr(VI) reduced Sirt1 expression and inhibited the deacetylation of Sirt1 to downstream key transcription factors, including nuclear factor erythroid 2-related factor 2 (Nrf2), Forkhead box O3 (FOXO3), and nuclear factor-kappa B (NF-κB). Conversely, when Res was administered as an activator of Sirt1, the deacetylation of Sirt1 was enhanced, and inflammatory response and apoptosis were significantly alleviated.

Conclusion

In summary, this work firstly demonstrates that Cr(VI) induces liver injury in rat by inhibiting the deacetylation of Sirt1, which is of positive significance for protecting the natural environment and animal health from chronic Cr poisoning.

Accumulated ambient air pollution and colon cancer incidence in Thailand

This research examined the relationship between colon cancer risks and pollution in various areas of Thailand, using satellites to gather quantities of aerosols in the atmosphere. Bayesian hierarchical spatio-temporal model and the Poisson log-linear model were used to examine the incidence rates of colon cancer standardized by national references; from the database of the National Health Security Office, Ministry of Public Health of Thailand and NASA's database from aerosol diagnostics model. Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) was used to explore disease-gender-specific spatio-temporal patterns of colon cancer incidences and accumulated air pollution-related cancers in Thailand between 2010 and 2016. A total of 59,605 patients were selected for the study. Due to concerns regarding statistical reliability between aerosol diagnostics model and colon cancer incidences, the posterior probabilities of risk appeared the most in dust PM_2.5. It could be interpreted as relative risk in every increase of 10 μg/m³ in black carbon, organic carbon, and dust-PM_2.5 levels were associated respectively with an increase of 4%, 4%, and 15% in the risks of colon cancer. A significant increase in the incidence of colon cancer with accumulated ambient air quality raised concerns regarding the prevention of air pollution. This study utilized data based on the incidences of colon cancer; the country's database and linked cancer data to pollution. According to the database from NASA's technology, this research has never been conducted in Thailand.