Environmental lead exposure and progression of chronic renal diseases in patients without diabetes

The impact of population ageing on the burden of chronic kidney disease

The burden of chronic kidney disease (CKD) and its risk factors are projected to rise in parallel with the rapidly ageing global population. By 2050, the prevalence of CKD category G3-G5 may exceed 10% in some regions, resulting in substantial health and economic burdens that will disproportionately affect lower-income countries. The extent to which the CKD epidemic can be mitigated depends largely on the uptake of prevention efforts to address modifiable risk factors, the implementation of cost-effective screening programmes for early detection of CKD in high-risk individuals and widespread access and affordability of new-generation kidney-protective drugs to prevent the development and delay the progression of CKD. Older patients require a multidisciplinary integrated approach to manage their multimorbidity, polypharmacy, high rates of adverse outcomes, mental health, fatigue and other age-related symptoms. In those who progress to kidney failure, comprehensive conservative management should be offered as a viable option during the shared decision-making process to collaboratively determine a treatment approach that respects the values and wishes of the patient. Interventions that maintain or improve quality of life, including pain management and palliative care services when appropriate, should also be made available.

Synergistic susceptibility to environmental lead toxicity in chronic kidney disease

PURPOSE OF REVIEW

While high levels of lead exposure, as occurs accidentally or occupationally, can cause toxicity across multiple organ systems, the hazard of commonly encountered levels of lead in the environment remains unresolved. Challenges to researching the health effects of lead include its complex interplay with renal function, rendering analyses at risk of unaccounted confounding, and the likely small effect size of environmental levels of exposure. While children are known to be disproportionately susceptible to lead toxicity, resulting in appropriately more stringent regulatory surveillance for those under 5 years old, emerging evidence suggests that those with chronic kidney disease (CKD) similarly are at a greater risk. This review summarizes the role of environmental lead toxicity as a potential cause and consequence of CKD.

RECENT FINDINGS

Whether environmental lead exposure causes CKD remains debatable, with little recent research advancing the conflicting, mostly cross-sectional, analyses from years ago. However, an emerging body of evidence suggests that CKD increases the susceptibility to lead toxicity. Higher circulating lead levels and lower urinary excretion result in greater lead accumulation in CKD, with simultaneous greater risk of clinically meaningful disease. Recent studies suggest that levels of lead found commonly in the United States drinking water supply, and currently permissible by the Environmental Protection Agency, associate with hematologic toxicity in those with advanced CKD. Whether environmental lead contamination may have additional negative health impact among this at-risk population, including cardiovascular and neurocognitive disease, warrants further study.

SUMMARY

The underlying pathophysiology of kidney disease synergizes the susceptibility to environmental lead toxicity for those with CKD. Low levels of exposure, as found commonly in the United States water supply, may have adverse health impact in CKD. Further research will be needed to determine if more stringent environmental regulations are warranted to protect the health of all.

Secular Trend in GFR Decline in Non-Dialysis CKD Based on Observational Data From Standard of Care Arms of Trials

RATIONALE & OBJECTIVE

The standard of care (SoC) group of randomized controlled trials (RCTs) is a useful setting to explore the secular trends in kidney disease progression because implementation of best clinical practices is pursued for all patients enrolled in trials. This meta-analysis evaluated the secular trend in the change of glomerular filtration rate (GFR) decline in the SoC arm of RCTs in chronic kidney disease (CKD) published in the last 30 years.

STUDY DESIGN

Systematic review and meta-analysis of the SoC arms of RCTs analyzed as an observational study.

SETTING & STUDY POPULATIONS

Adult patients with CKD enrolled in the SoC arm of RCTs.

SELECTION CRITERIA FOR STUDIES

Phase 3 RCTs evaluating GFR decline as an outcome in SoC arms.

DATA EXTRACTION

Two independent reviewers evaluated RCTs for eligibility and extracted relevant data.

ANALYTICAL APPROACH

The mean of GFR declines extracted in the SoC arm of selected RCTs were pooled by using a random effects model. Meta-regression analyses were performed to identify factors that may explain heterogeneity.

RESULTS

The SoC arms from 92 RCTs were included in the meta-analysis with a total of 32,202 patients. The overall mean GFR decline was-4.00 (95% CI, -4.55 to-3.44) mL/min/1.73m2 per year in the SoC arms with a high level of heterogeneity (I2, 98.4% [95% CI, 98.2-98.5], P<0.001). Meta-regression analysis showed an association between publication year (β estimate, 0.09 [95% CI, 0.032-0.148], P=0.003) and reduction in GFR over time. When evaluating publication decade categorically, GFR decline was-5.44 (95% CI, -7.15 to-3.73), -3.92 (95% CI, -4.82 to-3.02), and -3.20 (95% CI, -3.75 to -2.64) mL/min/1.73m2 per year during 1991-2000, 2001-2010, and 2011-2023, respectively. Using meta-regression, the heterogeneity of GFR decline was mainly explained by age and proteinuria.

LIMITATIONS

Different methods assessing GFR in selected trials and observational design of the study.

CONCLUSIONS

In the last 3 decades, GFR decline has decreased over time in patients enrolled in RCTs who received the standard of care.

TRIAL REGISTRATION

Registered at PROSPERO with record number CRD42022357704.

PLAIN-LANGUAGE SUMMARY

This study evaluated the secular trend in the change in glomerular filtration rate (GFR) decline in the placebo arms of randomized controlled trials (RCTs) that were studying approaches to protect the kidneys in the setting of chronic kidney disease. The placebo groups of RCTs are useful for examining whether the rate of progression of kidney disease has changed over time. We found an improvement in the slope of change in GFR over time. These findings suggest that adherence to standards of kidney care as implemented in clinical trials may be associated with improved clinical outcomes, and these data may inform the design of future RCTs in nephrology.

Involvement of Nrf2 Signaling in Lead-induced Toxicity

Nuclear factor erythroid 2-related factor 2 (Nrf2) is used as one of the main protective factors against various pathological processes, as it regulates cells resistant to oxidation. Several studies have extensively explored the relationship between environmental exposure to heavy metals, particularly lead (Pb), and the development of various human diseases. These metals have been reported to be able to, directly and indirectly, induce the production of reactive oxygen species (ROS) and cause oxidative stress in various organs. Since Nrf2 signaling is important in maintaining redox status, it has a dual role depending on the specific biological context. On the one hand, Nrf2 provides a protective mechanism against metal-induced toxicity; on the other hand, it can induce metalinduced carcinogenesis upon prolonged exposure and activation. Therefore, the aim of this review was to summarize the latest knowledge on the functional interrelation between toxic metals, such as Pb and Nrf2 signaling.

Identifying Sources of Lead Exposure for Children in the Republic of Georgia, with Lead Isotope Ratios

In the Republic of Georgia, a 2018 national survey estimated that more than 40% of children aged 2-7 years had a blood lead concentration (BLC) of more than 5 µg/dL. The objective of this study was to document the feasibility of employing lead isotope ratios (LIRs) to identify and rank the Pb (lead) exposure sources most relevant to children across Georgia. A cross-sectional survey between November 2019 and February 2020 of 36 children previously identified as having BLCs > 5 µg/dL from seven regions of Georgia involved the collection of blood and 528 environmental samples, a questionnaire on behaviours and potential exposures. The LIRs in blood and environmental samples were analysed in individual children and across the whole group to ascertain clustering. A fitted statistical mixed-effect model to LIR data first found that the blood samples clustered with spices, tea, and paint, then, further isotopically distinct from blood were sand, dust, and soil, and lastly, milk, toys, pens, flour, and water. Analysis of the LIRs provided an indication and ranking of the importance of Pb environmental sources as explanatory factors of BLCs across the group of children. The findings support the deployment of interventions aimed at managing the priority sources of exposure in this population.

Estimating the burden of diseases attributable to lead exposure in the North Africa and Middle East region, 1990-2019: a systematic analysis for the Global Burden of Disease study 2019

BACKGROUND

Lead exposure (LE) and its attributable deaths and disability-adjusted life years (DALYs) have declined in the recent decade; however, it remains one of the leading public health concerns, particularly in regions with low socio-demographic index (SDI) such as the North Africa and Middle East (NAME) region. Hence, we aimed to describe the attributable burden of the LE in this region.

METHODS

Data on deaths, DALYs, years of life lost (YLLs), and years lived with disability (YLDs) attributable to LE in the NAME region and its 21 countries from 1990 to 2019 were extracted from the Global Burden of Disease (GBD) 2019 study.

RESULTS

In 2019, the age-standardized death and DALY rates attributable to LE were 23.4 (95% uncertainty interval: 15.1 to 33.3) and 489.3 (320.5 to 669.6) per 100,000 in the region, respectively, both of which were higher among men than women. The overall age-standardized death and DALY rates showed 27.7% and 36.8% decreases, respectively, between 1990 and 2019. In this period, Bahrain, the United Arab Emirates, and Turkey had the highest decreases in the age-standardized death and DALY rates, while Afghanistan, Egypt, and Yemen had the lowest ones. Countries within high SDI quintile had lower attributable burden to LE compared with the low SDI quintile. Cardiovascular diseases and chronic kidney diseases accounted for the 414.2 (258.6 to 580.6) and 28.7 (17.7 to 41.7) LE attributable DALYs per 100,000 in 2019, respectively. The attributable YLDs was 46.4 (20.7 to 82.1) per 100,000 in 2019, which shows a 25.7% reduction (-30.8 to -22.5%) over 1990-2019.

CONCLUSIONS

The overall LE and its attributed burden by cause have decreased in the region from 1990-2019. Nevertheless, the application of cost-effective and long-term programs for decreasing LE and its consequences in NAME is needed.

Comparative Effects of Deferiprone and Salinomycin on Lead-Induced Disturbance in the Homeostasis of Intrarenal Essential Elements in Mice

Lead (Pb) exposure induces severe nephrotoxic effects in humans and animals. Herein, we compare the effects of two chelating agents, salinomycin and deferiprone, on Pb-induced renal alterations in mice and in the homeostasis of essential elements. Adult male mice (Institute of Cancer Research (ICR)) were randomized into four groups: control (Ctrl)—untreated mice administered distilled water for 28 days; Pb-exposed group (Pb)—mice administered orally an average daily dose of 80 mg/kg body weight (BW) lead (II) nitrate (Pb(NO₃)₂) during the first two weeks of the experimental protocol followed by the administration of distilled water for another two weeks; salinomycin-treated (Pb + Sal) group—Pb-exposed mice, administered an average daily dose of 16 mg/kg BW salinomycin for two weeks; deferiprone-treated (Pb + Def) group—Pb-exposed mice, administered an average daily dose of 20 mg/kg BW deferiprone for 14 days. The exposure of mice to Pb induced significant accumulation of the toxic metal in the kidneys and elicited inflammation with leukocyte infiltrations near the glomerulus. Biochemical analysis of the sera revealed that Pb significantly altered the renal function markers. Pb-induced renal toxicity was accompanied by a significant decrease in the endogenous renal concentrations of phosphorous (P), calcium (Ca), copper (Cu) and selenium (Se). In contrast to deferiprone, salinomycin significantly improved renal morphology in Pb-treated mice and decreased the Pb content by 13.62% compared to the Pb-exposed group. There was also a mild decrease in the renal endogenous concentration of magnesium (Mg) and elevation of the renal concentration of iron (Fe) in the salinomycin-treated group compared to controls. Overall, the results demonstrated that salinomycin is a more effective chelating agent for the treatment of Pb-induced alterations in renal morphology compared to deferiprone.

Hydrogels and Hydrogel Nanocomposites: Enhancing Healthcare through Human and Environmental Treatment

Humans are constantly exposed to exogenous chemicals throughout their life, which can lead to a multitude of negative health impacts. Advanced materials can play a key role in preventing or mitigating these impacts through a wide variety of applications. The tunable properties of hydrogels and hydrogel nanocomposites (e.g., swelling behavior, biocompatibility, stimuli responsiveness, functionality, etc.) have deemed them ideal platforms for removal of environmental contaminants, detoxification, and reduction of body burden from exogenous chemical exposures for prevention of disease initiation, and advanced treatment of chronic diseases, including cancer, diabetes, and cardiovascular disease. In this review, three main junctures where the use of hydrogel and hydrogel nanocomposite materials can intervene to positively impact human health are highlighted: 1) preventing exposures to environmental contaminants, 2) prophylactic treatments to prevent chronic disease initiation, and 3) treating chronic diseases after they have developed.

Chelation Therapy in Patients With Cardiovascular Disease: A Systematic Review

Background EDTA is an intravenous chelating agent with high affinity to divalent cations (lead, cadmium, and calcium) that may be beneficial in the treatment of cardiovascular disease (CVD). Although a large randomized clinical trial showed benefit, smaller studies were inconsistent. We conducted a systematic review of published studies to examine the effect of repeated EDTA on clinical outcomes in adults with CVD. Methods and Results We searched 3 databases (MEDLINE, Embase, and Cochrane) from database inception to October 2021 to identify all studies involving EDTA treatment in patients with CVD. Predetermined outcomes included mortality, disease severity, plasma biomarkers of disease chronicity, and quality of life. Twenty-four studies (4 randomized clinical trials, 15 prospective before/after studies, and 5 retrospective case series) assessed the use of repeated EDTA chelation treatment in patients with preexistent CVD. Of these, 17 studies (1 randomized clinical trial) found improvement in their respective outcomes following EDTA treatment. The largest improvements were observed in studies with high prevalence of participants with diabetes and/or severe occlusive arterial disease. A meta-analysis conducted with 4 studies reporting ankle-brachial index indicated an improvement of 0.08 (95% CI, 0.06-0.09) from baseline. Conclusions Overall, 17 studies suggested improved outcomes, 5 reported no statistically significant effect of treatment, and 2 reported no qualitative benefit. Repeated EDTA for CVD treatment may provide more benefit to patients with diabetes and severe peripheral arterial disease. Differences across infusion regimens, including dosage, solution components, and number of infusions, limit comparisons across studies. Additional research is necessary to confirm these findings and to evaluate the potential mediating role of metals. Registration URL: https://www.crd.york.ac.uk/; Unique identifier: CRD42020166505.

Single Nucleotide Polymorphism of TWIST2 May Be a Modifier for the Association between High-Density Lipoprotein Cholesterol and Blood Lead (Pb) Level

The association between lead (Pb) exposure and lower high-density lipoprotein cholesterol (HDL-C) was reported; however, the mechanism was unclear. Our purpose was to investigate the association of Pb, lipid profile, and to study the associated SNPs using a genome-wide association study (GWAS). A total of 511 participants were recruited to check blood Pb levels, lipid profile, and genotypes with Taiwan Biobank version 2.0 (TWB2). Our main result shows that HDL-C was significantly negatively associated with blood Pb levels, adjusted for gender, body mass index (BMI), and potential confounders. In addition, via the TWB2 GWAS, only two SNPs were found, including rs150813626 (single-nucleotide variation in the TWIST2 gene on chromosome 2), and rs1983079 (unclear SNP on chromosome 3). Compared to the rs150813626 GG carriers, the AA and AG carriers were significantly and negatively associated with HDL-C. We analyzed the interaction of rs150813626 SNP and blood Pb, and the HDL-C was consistently and negatively associated with blood Pb, male, BMI, and the rs150813626 AA and AG carriers. Moreover, the rs150813626 AA and blood Pb interaction was significantly and positively associated with HDL-C. In conclusion, the SNPs rs150813626 and rs1983079 were significantly associated with HDL-C in Pb-exposed workers. Furthermore, the interaction of rs150813626 AA and blood Pb had a positive influence on HDL-C. TWIST may inhibit osteoblast maturation, which might relate to bone Pb deposition and calcium metabolism. The mechanism needs more investigation in the future.

Trend in blood lead levels in Taiwanese adults 2005-2017

This study examined the trend of blood lead levels (BLLs) in Taiwanese adults and analyzed the variations in the BLL between Linkou (northern) and Kaohsiung (southern) hospital branches. Between 2005 and 2017, 3,804 adult participants received blood lead tests at the Linkou (n = 2,674) and Kaohsiung (n = 1,130) branches of Chang Gung Memorial Hospital. The geometric mean of BLL was 2.77 μg/dL. The adult participants from the Kaohsiung branch were not only age older (49.8±14.1 versus 39.4±14.2 years; P<0.001) and male predominant (65.8 versus 41.7%; P<0.001) but also showed a higher BLL (4.45±3.93 versus 2.82±2.42 μg/dL; P<0.001) and lower estimated glomerular filtration rate (87.62±25.94 versus 93.67±23.88; P<0.001) than those from the Linkou branch. Multivariable logistic regression analysis revealed that the Kaohsiung branch [odds ratio (OR): 7.143; 95% confident interval (CI): 5.682–8.929; P<0.001], older age (OR: 1.008; 95% CI: 1.000–1.015; P = 0.043) and reduced estimated glomerular filtration rate (OR: 1.009; 95% CI: 1.004–1.014; P = 0.001) were significant predictors for BLL > 5 μg/dL. Therefore, this study confirmed a continuous decreasing trend in the BLL in Taiwan after banning leaded petrol in 2000.

Reduction in Blood Lead Concentration in Children across the Republic of Georgia following Interventions to Address Widespread Exceedance of Reference Value in 2019

In recent years, reports of lead contamination have dramatically increased in Georgia. Given concerns about the exposure of children to lead (Pb), the National Multiple Indicator Cluster Survey (MICS-2018) included a blood sampling component. The results showed that 41% of the children that participated had blood Pb levels (BLL) ≥ 5 µg/dL and that BLL in children living in Western Georgia were higher than those in Eastern regions. In response to these findings, NCDC implemented written and verbal advice to the families of children who participated in the MICS-2018 on how to reduce Pb exposure. From August 2019 onwards, the state program of clinical follow-up was implemented. The design of this study was a longitudinal study. The intervention of interest was the public health advice and medical follow-up, and the outcome was defined as the difference in BLL between the MICS-2018 survey and the state program follow-up. We observed a significant overall reduction in median BLL between MICS-2018 and state program follow-up in both August 2019 and the latest results (until December 2019). However, we did not observe any significant further reduction between August and the most recent BLL results. In the Georgian setting, written and verbal communication targeting individual households, alongside home visits to the most exposed, effectively reduced BLL in children.

Serum catalytic iron and progression of chronic kidney disease: findings from the ICKD study

BACKGROUND

The non-transferrin bound catalytic iron moiety catalyses production of toxic reactive oxygen species and is associated with adverse outcomes. We hypothesized that serum catalytic iron (SCI) is associated with progression of chronic kidney disease (CKD).

METHODS

Baseline samples of the Indian Chronic Kidney Disease participants with at least one follow up visit were tested for total iron, iron binding capacity, transferrin saturation, SCI, ferritin and hepcidin. SCI was measured using the bleomycin-detectable iron assay that detects biologically active iron. Association with the incidence of major kidney endpoints, (MAKE, a composite of kidney death, kidney failure or > 40% loss of eGFR) was examined using Cox proportional hazards model adjusted for sex and age.

RESULTS

2002 subjects (49.9 ± 11.6 years, 68.1% males, baseline eGFR 41.01 ml/min/1.73m2) were enrolled. After a median follow up of 12.6 (12.2, 16.7) months, the composite MAKE occurred in 280 (14%). After adjusting for age and sex, increase from 25th to 75th percentile in SCI, transferrin saturation, ferritin and hepcidin were associated with 78% (43-122%), 34% (10-62%), 57% (24-100%) and 74% (35-124%) increase in hazard of MAKE, respectively. SCI was associated with MAKE and kidney failure after adjustment for occupational exposure, hypertension, diabetes, tobacco, alcohol use, history of AKI, baseline eGFR, uACR, and allowing baseline hazard to vary by centre.

CONCLUSIONS

SCI is strongly and independently associated with composite MAKE in patients with mild to moderate CKD. Confirmation in other studies will allow consideration of SCI as a risk marker and treatment target.

Blood lead, nutrient intake, and renal function among type 2 diabetic patients

Lead (Pb) exposure has been reported to have nephrotoxicity. However, such an effect has not been well investigated in type 2 diabetes (T2D) patients, especially when taking into account the nutrition status of the patients. Therefore, we explore the association between blood lead levels (BLLs), dietary intake of nutrients, and impaired renal function among patients with T2D. We measured BLLs and biochemical parameters of renal injury in 780 patients. Dietary nutrients intake was assessed by a food frequency questionnaire in 420 of 780 participants. We found high BLLs were significantly associated with certain parameters of renal injury, and dietary intake of specific nutrients (mainly micronutrients) was associated with reduced BLLs at high percentile distribution of concentration. BLLs were also found to have moderation effects on the association between specific dietary nutrients and specific renal function parameters.

Heavy Metal Toxicity in Chronic Renal Failure and Cardiovascular Disease: Possible Role for Chelation Therapy

Exposure to heavy metals is common. This exposure is related to environmental contamination of air, water and soil, occupational exposure, accumulation in food, tobacco, and other factors. Cadmium and lead are notable for their widespread contamination, long-lasting effects in the body, and renal as well as cardiovascular toxicity. Acute toxicity due to high-level exposure, as well as chronic low-level exposure are now well-established pathogenic entities. Both chronic renal failure and ischemic heart disease patients have been treated separately in recent studies with ethylenediaminetetraacetic acid (EDTA) chelation therapy. In patients with chronic kidney disease (serum creatinine: 1.5-4.0 mg/dL) and increased body lead burden, weekly low-dose chelation with calcium EDTA slowed the rate of decline in renal function in patients with diabetes and in non-diabetic patients. In patients with a history of myocardial infarction, the Trial to Assess Chelation Therapy study showed that EDTA chelation decreased the likelihood of cardiovascular events, particularly in patients with diabetes. However, heavy metal levels were not measured in this study. It is clear that more research is needed in this area. There is also a need to more frequently consider and test for the possibility of cadmium and lead toxicity in patients with increased risk, such as those with hypertension, diabetes mellitus, and chronic renal disease.

Periodontal disease as a predictor of chronic kidney disease (CKD) stage in older adults

Objective

The aim of this study was to evaluate periodontal disease as a predictor of chronic kidney disease (CKD) stage in older adults.

Methods

A total of 1159 adults aged 65 to 80 years and diagnosed with periodontal disease and CKD (stages 1, 2, and 3) were randomly selected for a cross-sectional study. Periodontal status was assessed using the Community Periodontal Index of Treatment Needs (CPITN) and CKD was staged using the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) guidelines.

Results

In patients with stage 1 CKD, the odds ratios (ORs) (95% confidence intervals [CIs]) for CPITN-1, CPITN-2, CPITN-3, and CPITN-4 were 1.13 (0.83–1.55), 1.47 (1.13–1.81), 1, and 1, respectively. In patients with stage 2 CKD, the ORs (95% CIs) for CPITN-1, CPITN-2, CPITN-3, and CPITN-4 were 1.49 (1.14–1.93), 1.37 (1.02–1.78), 3.07 (2.81–3.25), and 3.65 (3.49–3.71), respectively. In patients with stage 3 CKD, the ORs (95% CIs) for CPITN-1, CPITN-2, CPITN-3, and CPITN-4 were 1, 1, 4.61 (4.47–5.21), and 5.23 (5.14–5.47), respectively.

Conclusion

The highest CPITN values (CPITN-3 and CPITN-4) were associated with CKD stages 2 and 3. Thus, periodontal disease may be associated with progression of CKD.

Lead (Pb) exposure and heart failure risk

Lead (Pb) is a heavy metal with widespread industrial use, but it is also a widespread environmental contaminant with serious toxicological consequences to many species. Pb exposure adversely impacts the cardiovascular system in humans, leading to cardiac dysfunction, but its effects on heart failure risk remain poorly elucidated. To better understand the pathophysiological effects of Pb, we review potential mechanisms by which Pb exposure leads to cardiac dysfunction. Adverse effects of Pb exposure on cardiac function include heart failure risk, pressure overload, arrhythmia, myocardial ischemia, and cardiotoxicity. The data reviewed clearly establish that Pb exposure can play an important role in the occurrence and development of heart failure. Future epidemiological and mechanistic studies should be developed to better understand the involvement of Pb exposure in heart failure.

The Case For Cadmium and Lead Heavy Metal Screening

Exposure to cadmium and lead is widespread, and is related to environmental contamination, occupational sources, food, tobacco and other consumer products. Lower socioeconomic status increases the risk of heavy metal exposure and the diseases associated with cadmium and lead toxicity. Concurrent toxicity with both cadmium and lead is likely but has not often been assessed. There is now substantial evidence linking cadmium and lead to many diseases including hypertension, diabetes mellitus, obesity, cancer, coronary artery disease, chronic kidney disease (CKD) and lung disease. Both chronic renal failure and ischemic heart disease patients have been treated separately in recent studies with calcium disodium ethylenediaminetetraacetic acid (Ca EDTA) chelation therapy. In patients with CKD, serum creatinine 1.5-4.0 mg/dL, and increased body lead burden, weekly low dose chelation with Ca EDTA slowed the rate of decline in renal function in diabetics and non-diabetics. In patients with a history of myocardial infarction, the Trial to Assess Chelation Therapy (TACT) study showed that Ca EDTA chelation decreased the likelihood of cardiovascular events, particularly in diabetics. Ca EDTA chelation administered carefully at lower dosage (<50 mg/kg per week) is generally safe. In the past, acute renal failure associated with much higher dosage was reported. We suggest that the preponderance of the evidence favors a more activist approach towards diagnosis and possible intervention in heavy metal toxicity.

Blood lead, vitamin D status, and albuminuria in patients with type 2 diabetes

Environmental lead exposure has been linked with reduced kidney function. However, evidence about its role in diabetic kidney damage, especially when considering the nutritional status of vitamin D, is sparse. In this observational study, we investigated the association between low-level lead exposure and urinary albumin-to-creatinine ratio (UACR) and assessed potential impact of vitamin D among 4033 diabetic patients in Shanghai, China. Whole blood lead was measured by graphite furnace atomic absorption spectrometry. Serum 25-hydroxyvitamin D [25(OH)D] was tested using a chemiluminescence immunoassay. The associations of blood lead with UACR and albuminuria, defined as UACR ≥30 mg/g, according to 25(OH)D levels were analyzed using linear and Poisson regression models. A doubling of blood lead level was associated with a 10.7% higher UACR (95% CI, 6.19%-15.5%) in diabetic patients with 25(OH)D < 50 nmol/L, whereas the association was attenuated toward null (2.03%; 95% CI, -5.18% to 9.78%) in those with 25(OH)D ≥ 50 nmol/L. Similarly, the risk ratios of prevalent albuminuria per doubling of blood lead level between the two groups were 1.09 (95% CI, 1.03-1.15) and 0.99 (95% CI, 0.86-1.14), respectively. Joint analysis demonstrated that a combination of high blood lead and low 25(OH)D corresponded to significantly higher UACR. Among diabetic patients with 25(OH)D < 50 nmol/L, the increment of UACR relative to blood lead was more remarkable in those with reduced estimated glomerular filtration rate (<60 mL/min/1.73 m²). These results suggested that higher blood lead levels were associated with increased urinary albumin excretion in diabetic patients with vitamin D deficiency. Further prospective studies are needed to validate our findings and to determine whether vitamin D supplementation yields a benefit.

Mapping lead concentrations in urban topsoil using proximal and remote sensing data and hybrid statistical approaches

Due to rapid urbanization in China, lead (Pb) continues to accumulate in urban topsoil, resulting in soil degradation and increased public exposure. Mapping Pb concentrations in urban topsoil is therefore vital for the evaluation and control of this exposure risk. This study developed spatial models to map Pb concentrations in urban topsoil using proximal and remote sensing data. Proximal sensing reflectance spectra (350-2500 nm) of soils were pre-processed and used to calculate the principal components as landscape factors to represent the soil properties. Other landscape factors, including vegetation and land-use factors, were extracted from time-sequential Landsat images. Two hybrid statistical approaches, regression kriging (RK) and geographically weighted regression (GWR), were adopted to establish prediction models using the landscape factors. The results indicated that the use of landscape factors derived from combined remote and proximal sensing data improved the prediction of Pb concentrations compared with useing these data individually. GWR obtained better results than RK for predicting soil Pb concentration. Thus, joint proximal and remote sensing provides timely, easily accessible, and suitable data for extracting landscape factors.

Plasma cadmium is associated with increased risk of long-term kidney graft failure

The kidney is one of the most sensitive organs to cadmium-induced toxicity, particularly in conditions of long-term oxidative stress. We hypothesized that, in kidney transplant recipients, nephrotoxic exposure to cadmium represents an overlooked hazard for optimal graft function. To test this, we performed a prospective cohort study and included 672 outpatient kidney transplant recipients with a functioning graft of beyond one year. The median plasma cadmium was 58 ng/L. During a median 4.9 years of follow-up, 78 kidney transplant recipients developed graft failure with a significantly different distribution across tertiles of plasma cadmium (13, 26, and 39 events, respectively). Plasma cadmium was associated with an increased risk of graft failure (hazard ratio 1.96, 95% confidence interval 1.56‒2.47 per log₂ ng/L). Similarly, a dose-response relationship was observed over increasing tertiles of plasma cadmium, after adjustments for potential confounders (donor, recipient, transplant and lifestyle characteristics), robust in both competing risk and sensitivity analyses. These findings were also consistent for kidney function decline (graft failure or doubling of serum creatinine). Thus, plasma cadmium is independently associated with an increased risk of long-term kidney graft failure and decline in kidney function. Further studies are needed to investigate whether exposure to cadmium represents an otherwise overlooked modifiable risk factor for adverse long-term graft outcomes in different populations.

Lifestyle-Related Exposure to Cadmium and Lead is Associated with Diabetic Kidney Disease

BACKGROUND

Environmental factors contributing to diabetic kidney disease are incompletely understood. We investigated whether blood cadmium and lead concentrations were associated with the prevalence of diabetic kidney disease, and to what extent lifestyle-related exposures (diet and smoking) contribute to blood cadmium and lead concentrations.

MATERIAL AND METHODS

In a cross-sectional analysis in 231 patients with type 2 diabetes included in the DIAbetes and LifEstyle Cohort Twente (DIALECT-1), blood cadmium and lead concentrations were determined using inductively coupled plasma mass spectrometry. The associations between diet (derived from food frequency questionnaire), smoking and cadmium and lead were determined using multivariate linear regression. The associations between cadmium and lead and diabetic kidney disease (albumin excretion >30 mg/24 h and/or creatinine clearance <60 mL/min/1.73 m²) were determined using multivariate logistic regression.

RESULTS

Median blood concentrations were 2.94 nmol/L (interquartile range (IQR): 1.78-4.98 nmol/L) for cadmium and 0.07 µmol/L (IQR: 0.04-0.09 µmol/L) for lead, i.e., below acute toxicity values. Every doubling of lead concentration was associated with a 1.75 (95% confidence interval (CI): 1.11-2.74) times higher risk for albuminuria. In addition, both cadmium (odds ratio (OR) 1.50 95% CI: 1.02-2.21) and lead (OR 1.83 95% CI: 1.07-3.15) were associated with an increased risk for reduced creatinine clearance. Both passive smoking and active smoking were positively associated with cadmium concentration. Alcohol intake was positively associated with lead concentration. No positive associations were found between dietary intake and cadmium or lead.

CONCLUSIONS

The association between cadmium and lead and the prevalence of diabetic kidney disease suggests cadmium and lead might contribute to the development of diabetic kidney disease. Exposure to cadmium and lead could be a so far underappreciated nephrotoxic mechanism of smoking and alcohol consumption.

Effects of Vitamin D Receptor, Metallothionein 1A, and 2A Gene Polymorphisms on Toxicity of the Peripheral Nervous System in Chronically Lead-Exposed Workers

Chronic exposure to lead is neurotoxic to the human peripheral sensory system. Variant vitamin D receptor (VDR) genes and polymorphisms of metallothioneins (MTs) are associated with different outcomes following lead toxicity. However, no evidence of a relationship between lead neurotoxicity and polymorphisms has previously been presented. In this study, we investigated the relationship between the polymorphisms of VDR, MT1A, and MT2A genes and lead toxicity following chronic occupational lead exposure. We measured vibration perception thresholds (VPT) and current perception thresholds (CPT) in 181 workers annually for five years. The outcome variables were correlated to the subject's index of long-term lead exposure. Polymorphisms of VDR, MT1A, and MT2A were defined. The potential confounders, including age, sex, height, smoking, alcohol consumption, and working life span, were also collected and analyzed using linear regression. The regression coefficients of some gene polymorphisms were at least 20 times larger than regression coefficients of time-weighted index of cumulative blood lead (TWICL) measures. All regression coefficients of TWICL increased slightly. MT1A rs11640851 (AA/CC) was associated with a statistically significant difference in all neurological outcomes except hand and foot VPT. MT1A rs8052394 was associated with statistically significant differences in hand and foot CPT 2000 Hz. In MT2A rs10636, those with the C allele showed a greater effect on hand CPT than those with the G allele. Among the VDR gene polymorphisms, the Apa rs7975232 (CC/AA) single nucleotide polymorphism was associated with the greatest difference in hand CPT. MT2A rs28366003 appeared to have a neural protective effect, whereas Apa (rs7975232) of VDR and MT2A rs10636 increased the neurotoxicity as measured by CPT in the hands. MT1A rs8052394 had a protective effect on large myelinated nerves. MT1A rs11640851 was associated with susceptibility to neurotoxicity.

Model-based meta-analysis of individual International Prostate Symptom Score trajectories in patients with benign prostatic hyperplasia with moderate or severe symptoms

Aims

International Prostate Symptom Score (IPSS) is a marker of lower urinary tract symptoms (LUTS) deterioration or improvement in benign prostate hyperplasia (BPH). Whereas changes in IPSS relative to baseline have been used as endpoints in clinical trials, little attention has been given to the time course of symptoms. The current investigation aimed to develop a drug‐disease model to describe individual IPSS trajectories in moderate and severe BPH patients.

Methods

A model‐based meta‐analytical approach was used including data from 10 238 patients enrolled into Phase III and IV studies receiving placebo, tamsulosin, dutasteride or combination therapy over a period of up to 4 years. Model predictive performance was assessed using statistical and graphical criteria. Subsequently, simulations were performed to illustrate the implications of treatment with drugs showing symptomatic and disease‐modifying properties in patients with varying disease progression rates.

Results

Improvement and worsening of IPSS could be characterized by a model including a sigmoid function which disentangles drug effects from placebo and varying disease progression rates on IPSS. Mean estimate (95% confidence intervals) for the disease progression rate was 0.319 (0.271–0.411) month⁻¹. Treatment effect on IPSS (DELTA) was found to be 0.0605, 0.0139 and 0.0310 month⁻¹ for placebo, tamsulosin and combination therapy, respectively. In addition, it appears that individual trajectories can be clustered together into different phenotypes describing the underlying disease progression rate (i.e. slow, moderate and fast progressors).

Conclusions

The availability of a drug‐disease model enables the evaluation of interindividual differences in disease progression rate, deterioration of symptoms and treatment effects on LUTS/BPH.

Blood lead level: an overlooked risk of carpal tunnel syndrome in hemodialysis patients

Introduction: Carpal tunnel syndrome (CTS) is a severe complication observed in long-term maintenance hemodialysis (MHD) patients. The most common cause of CTS is dialysis-related β2-microglobulin amyloidosis, which is associated with inflammation and oxidative stress in dialysis patients. Patients on MHD have higher blood lead levels (BLLs) than the general population. Lead (Pb) exposure in chronic dialysis patients has been noted to induce oxidative stress and inflammation. Therefore, lead-related inflammation and oxidative stress might contribute to CTS. Methods: The medical records of 866 MHD patients were reviewed. Two hundred and thirty-four patients with symptoms of CTS were surveyed by senior neurologists via physical examinations and nerve conduction studies. Patients in this study were stratified into groups with low-normal (<10 μg/dL), high-normal (10 to 20 μg/dL), and abnormal (>20 μg/dL) BLLs. The associations between CTS and BLLs and the clinical data were analyzed. Results: Multivariate logistic regression analyses showed that Log BLL (OR: 54.810, 95% CI: 13.622-220.54, p < .001), high-normal BLLs (OR: 4.839, 95% CI: 2.262-10.351, p < .001) with low-normal BLL as a reference, high BLLs (OR: 12.952, 95% CI: 5.391-31.119, p < .001) with low-normal BLL as a reference, and a BLL >12.3 μg/dL (OR: 6.827, 95% CI: 3.737-12.472, p < .001) were positively associated with CTS according to three different analyses. Discussion: In conclusion, blood lead levels were positively associated with CTS in patients on MHD. Dialysis patients should pay more attention to their environmental exposure to Pb. Avoidance of environmental Pb may reduce the incidence of CTS in MHD patients. Future studies will address the role of Pb in the pathophysiology of CTS in this patient population.

Simultaneous Removal of Residual Sulfate and Heavy Metals from Spent Electrolyte of Lead-Acid Battery after Precipitation and Carbonation

Spent electrolyte from lead-acid battery contains high concentrations of sulfate acid and heavy metals; therefore without proper handling, they might cause severe environmental pollution. A relatively high concentration of sulfate ions (approximately 3000 mg/L) and heavy metals still exists in the effluent even after precipitation with slaked lime and carbonation process, which need to be further processed to lower both the concentrations of sulfate and heavy metals for direct discharge. A process that involves the reduction of sulfate to sulfide with sulfate-reducing bacteria and precipitation of the excessive sulfide with Fe(OH)2 was adopted to dispose of the effluent after precipitation and carbonation for direct discharge. Thermodynamic calculations were adopted to narrow down the optimum experimental range and understand the precipitation mechanism. In the whole process, no new impurities nor ions were introduced and 99.2% of sulfate, 99.9% of sulfide, 99.1% of Ca and more than 94.6% of Pb and 99.8% of Cd were removed and the obtained effluent was safe to discharge.

The chemical exposome of type 2 diabetes mellitus: Opportunities and challenges in the omics era

Type 2 diabetes mellitus (T2DM) is a global silent killer, with > 450 million affected adults worldwide. A diverse array of non-modifiable risk factors such as family history, age (> 45 yrs), race/ethnicity, genetics, and history of gestational diabetes and modifiable risk factors such as physical inactivity, high body fat, body weight, high blood pressure, and high cholesterol for progression of prediabetes to T2DM. Given, that the modern world human population is constantly exposed to multiple stressors in the form of physical (i.e., sound, weather etc.) and chemical environment (i.e., diet, pollutants etc.), industrialization, and modernization has led to form a basis for exposomal correlation with T2DM incidence. Over the past decade, there have been emerging reports on association of levels of persistent organic pollutants (POPs), phthalates, antibiotics, drugs, air pollution, pesticides, and heavy metals with T2DM. In this review, we discuss the well known chemical exposome that has been associated with T2DM; the tools and approaches to capture this chemical exposome, and future opportunities and challenges in this exciting area of research. We further provide a window of thoughts, whether omics technologies can help fill in the gaps to help provide high throughput exposomics datasets in an unbiased manner to help understand T2DM pathophysiology in the context of industrialization, drastic lifestyle changes, urbanization, and pollution. We also discuss and provide guidelines/call to action for future exposomics studies investigating the association of T2DM with exposomes in the context of both epidemiological and experimental approaches.

Diversity of metals and metal-interactive bacterial populations in different types of Arctic snow and frost flowers: Implications on snow freeze-melt processes in a changing climate

Arctic snow has been shown to be a reactive interface for key physical, chemical, and microbiological processes, affecting the Arctic's oxidation, biodiversity, radiation, and climate. To explore the potential links between snow-borne metal contaminants and metal-interactive bacteria, to freezing/melting processes, we performed concurrent chemical characterization, genomic, and morphological analysis of five different Arctic snowpack (accumulated, blowing, fresh falling, surface hoar, and wind pack snow) and frost flower in Utqiaġvik (Barrow), Alaska, using Montreal urban snow as reference. Several complementary analytical techniques, including triple quad ICP-MS/MS along with various chromatography techniques, thermal ionization mass spectrometer (TIMS), high-resolution transition electron microscopy with electron dispersive X-ray spectroscopy (HR-TEM/EDS), and next generation sequencing (NGS), were deployed. Distinct metal composition and bacterial distribution among samples were observed. The concentration of 27 different transition, post-transition, rare, and radioactive metals were determined in molten snow and frost flower, as well as filtered samples. The range of three highest detected metal concentrations among samples were: Hg (3.294-134.485 μg/L), Fe (0.719-34.469 μg/L), and Sr (1.676-19,297.000 μg/L). NGS analysis led to the identification of metal interacting bacteria in all types of snow and frost flowers in the Arctic (blowing snow (1239), surface hoar snow (2243), windpack (2431), frost flowers (1440)), and Montreal urban snow (5498)) with specific bacterial genera such as: Acinetobacter, Arcenicella, Azospirillum (surface hoar snow), Arthrobacter, Paenibacillus (blowing snow), and Cycloclasticus, OM182 clade (frost flower). Several types of bacteria with confirmed or associated ice nucleation activity were observed in different types of snow, and frost flower including Pseudomonas genera (e.g., Pseudomonas fluorescens), Flavobacterium, Corynebacterium, and Pseudoxanthomonas. The implications of the above findings to snow-air interactions including nanoparticles, namely during melting and freezing cycles, and to probe the impact of various natural and anthropogenic activities are herein discussed.

Association of low-level blood lead with serum uric acid in U.S. adolescents: a cross-sectional study

BACKGROUND

Uncertainty remains regarding the association between blood lead levels (BLL) and serum uric acid (SUA) with relatively low BLL exposure because of limited data in the adolescent population. We examined the association between BLL and SUA in U.S. adolescents.

METHODS

In this cross-sectional study, 8303 adolescents aged 12-19 years from NHANES 1999-2006 were analyzed. BLL was Ln-transformed for analysis for the skewed distribution. Elevated SUA was defined as ≥5.5 mg/dL. Multivariate linear and multiple logistic regression analyses were performed to evaluate the association of BLL with SUA and elevated SUA. Moreover, a generalized additive model (GAM) and a fitted smoothing curve (penalized spline method) were conducted.

RESULTS

The overall mean BLL was 1.3 μg/dL. Multivariate linear regression analyses showed that LnBLL was independently and positively correlated with SUA level (β = 0.13, 95%CI: 0.09-0.17). Multiple logistic analyses showed that LnBLL was associated with a 24% increased prevalence of elevated SUA (OR = 1.24; 95% CI, 1.11-1.38). Analyses using restricted cubic spline confirmed that the associations of LnBLL with SUA and elevated SUA were linear. Subgroup analyses showed that stronger associations between LnBLL and SUA were detected in adolescents with lower levels of education and estimated glomerular filtration rate (eGFR) (all P for interaction < 0.05).

CONCLUSIONS

BLL was independently and positively correlated with SUA level and elevated SUA among U.S. adolescents, particularly with lower levels of education and eGFR. The data suggest that there is no "safe" threshold level of exposure to lead.

Potential Ecological Risk and Health Risk Assessment of Heavy Metals and Metalloid in Soil around Xunyang Mining Areas

Xunyang is rich in various metal minerals and is one of the four major metal mining areas in Shaanxi province, China. To explore the effects of soil heavy metals and metalloid pollution on the environment and human health around the mining areas, four places—Donghecun (D), Gongguan (G), Qingtonggou (Q) and Nanshagou (N)—were selected as the sampling sites. Potential ecological risk (PER) and health risk assessment (HRA) models were used to analyze the environmental and health risks around the mining areas. The concentration of heavy metals (Cd, Cr, Pb, Zn, Ni, Cu, Hg) and metalloid (As) in cultivated land in the vicinity of Xunyang mining areas indicated that, except for Cu, the remaining elements detected exceeded the threshold values at some sites. The geo-accumulation index (IGeo) revealed that soils in G and Q could be identified as being extremely contaminated. PER indicated that there was significantly high risk at G and Q for Hg. In N, Pb recorded the highest E r i , which also demonstrates a considerable pre-existing risk. HRA indicated that the hazard index (HI) for both carcinogenic and non-carcinogenic risks was much higher among children than among adults, and the ingestion pathway contributed the greatest risk to human health, followed by the dermal pathway and inhalation. Because the HI values of the metals and metalloid in the study areas were all lower than 1, there was no significant non-carcinogenic risk. However, the carcinogenic risk for Cr is relatively higher, surpassing the tolerable values in G, Q, and N. This study analyzed the ecological risks and human health risks of heavy metals and metalloid in farmland soils near the sampling mining areas, and demonstrated the importance of environmental changes caused by land development in the mining industry.

The effect of EDTA-based chelation on patients with diabetes and peripheral artery disease in the Trial to Assess Chelation Therapy (TACT)

OBJECTIVE

Approximately 1 in 7 US adults have diabetes; and over 60% of deaths in patients with diabetes have cardiac disease as a principal or contributing cause. Both coronary and peripheral artery disease (PAD) identify high-risk cohorts among patients with diabetes. We have previously demonstrated improved cardiovascular outcomes with edetate disodium-based chelation in post-MI patients with diabetes, enrolled in the Trial to Assess Chelation Therapy (TACT). In these analyses we further studied the effect size of patients with diabetes and severe disease in 2 vascular beds; coronaries, and lower extremity arteries. We questioned whether greater atherosclerotic burden would attenuate the observed beneficial effect of edetate disodium infusions.

RESEARCH DESIGN AND METHODS

The multicenter TACT used a double blind, placebo controlled, 2 × 2 factorial design with 1708 participants, randomly assigned to receive edetate disodium-based chelation, or placebo and high dose oral vitamins or placebo. There were 162 (9.5% of 1708) post-MI patients with a diagnosis of diabetes mellitus and PAD for this post hoc analysis. Patients received up to 40 double-blind intravenous infusions of edetate disodium-based chelation, or placebo. The composite primary endpoint of TACT consisted of death from any cause, myocardial infarction, stroke, coronary revascularization and hospitalization for angina.

RESULTS

The median age was 66 years, 15% female, 5% non-Caucasian, and BMI was 31. Insulin was used by 32% of patients. Active infusions significantly reduced the primary endpoint compared with placebo infusions (HR, 0.52; 95% CI, 0.30-0.92; P = 0.0069), with a 30% absolute risk reduction in the primary endpoint. There was a marked reduction in total mortality from 24% to 11%, although of borderline significance (P = 0.052).

CONCLUSION

Atherosclerotic disease in multiple vascular beds did not attenuate the beneficial effect of edetate disodium infusions in post MI patients with diabetes. Studies now in progress will prospectively test this post hoc finding.

Chronic kidney disease in the context of toxic effects the working chemical factors (literature review)

The article analyzes the publications devoted to the problem of professional renal lesions caused by chemical factors. Classification, prevalence, peculiarities of the clinical picture, diagnosis of professional renal lesions caused by chemical factors of the production environment are reviewed. The frequency of professional renal lesions remains underestimated due to low manifestation of symptoms and the influence of environmental factors, which require further investigation of this issue.

Interstitial Nephritis Presenting as Acute Kidney Injury Following Ingestion of Alternative Medicine Containing Lead: A Case Report

Introduction:

Some studies have shown that patients consuming alternate medicine can suffer from complications like acute kidney injury (AKI) due to heavy metal poisoning. The use of traditional ayurvedic herbal remedies may be difficult to identify as a source of toxicity, especially if the treating doctor is not aware of this habit, unless a detailed history is taken. In this report, we describe a patient who had consumed ayurvedic supplements for treating fever and abdominal pain and presented to our emergency department (ED) with AKI.

Case presentation:

A 24-year-old male presented to the ED with complaints of abdominal pain, fever and loose stools. His blood tests revealed AKI and he was started on emergency hemodialysis. His renal function improved after only one cycle of dialysis and he was discharged in a stable condition.

Conclusion:

Acute lead toxicity should be suspected in patients with abdominal and neurological dysfunction who have a history of chronic ayurvedic medicine intake and thus should be promptly treated. Physicians should rule out potential toxicity from these supplements and have a heightened level of suspicion for lead toxicity in patients presenting with abdominal pain and AKI without any obvious cause.

Hyperspectral Prediction Model of Metal Content in Soil Based on the Genetic Ant Colony Algorithm

The accumulation of metals in soil harms human health through different channels. Therefore, it is very important to conduct fast and effective non-destructive prediction of metals in the soil. In this study, we investigate the characteristics of four metal contents, namely, Sb, Pb, Cr, and Co, in the soil of the Houzhai River Watershed in Guizhou Province, China, and establish the content prediction back propagation (BP) neural network and genetic-ant colony algorithm BP (GAACA-BP) neural network models based on hyperspectral data. Results reveal that the four metals in the soil have different degrees of accumulation in the study area, and the correlation between them is significant, indicating that their sources may be similar. The fitting effect and accuracy of the GAACA-BP model are greatly improved compared with those of the BP model. The R values are above 0.7, the MRE is reduced to between 6% and 15%, and the validation accuracy is increased by 12–64%. The prediction ability of the model of the four metals is Cr > Co > Sb > Pb. These results indicate the possibility of using hyperspectral techniques to predict metal content.

Protocol and baseline data for a prospective open-label explorative randomized single-center comparative study to determine the effects of various intravenous iron preparations on markers of oxidative stress and kidney injury in chronic kidney disease (IRON-CKD)

BACKGROUND

Intravenous (IV) iron is frequently used to treat iron deficiency/anemia in patients who are unable to tolerate oral iron or the oral iron is not sufficient toreplete iron requirements. However, safety concerns regarding the potential increase in oxidative stress and other adverse effects persist and it remains unclear whether all iron preparations are equivalent. Indeed, the comparative risk of adverse events with IV iron preparations has not been extensively assessed. We hypothesize that IV iron leads to changes in oxidative stress, endothelial function, and potential renal damage depending on the iron formulation (related to the generation of "free" or catalytic labile iron) and this may result in more tubular and glomerular injury manifested as increased proteinuria and raised neutrophil gelatinase-associated lipocalin (NGAL) levels in patients with chronic kidney disease (CKD).

METHODS

IRON-CKD is a prospective, open-label, explorative, randomized, single-center study designed to compare the safety and efficacy of three parenteral iron preparations: low-molecular-weight iron dextran-Cosmofer, iron sucrose-Venofer, and iron isomaltoside-Monofer. The study includes 40 adults who have established CKD stages 3-5 and serum ferritin (SF) of less than 200 μg/L or transferrin saturation (TS) of less than 20% (or both); they were randomly assigned in a 1:1:1:1 ratio to 200 mg iron dextran, 200 mg iron sucrose, 200 mg iron isomaltoside, or 1000 mg iron isomaltoside. After randomization, participants undergo baseline assessments and then an iron infusion. Each participant is followed up at 2 h, day 1, week 1, and months 1 and 3. At each follow-up visit, patients undergo clinical review, measurement of pulse wave velocity (PWV), blood tests for renal function, and collection of serum/plasma samples for oxidative stress and inflammatory markers. The primary outcomes are measures of oxidative stress, inflammatory markers, and markers of acute renal injury in comparison with baseline measures of each iron preparation and between each of the iron preparations. Secondary objectives include effects on hematinic profiles and hemoglobin concentrations, changes in arterial stiffness, incidence of significant side effects, and change in patients' quality of life.

RESULTS

Between October 2015 and April 2018, 521 individuals were identified as potential participants; 216 were contacted, 56 expressed an interest, 49 attended a screening visit, and 40 were confirmed to meet the eligibility criteria and were randomly assigned. The mean age was 58.8 (standard error of the mean 2.2) years, and 23 (58%) were male. All patients were white and English-speaking. The mean SF was 68.8 μg/L, TS was 21.4%, and haemoglobin was 122.6 g/L at randomization for the whole group. The mean estimated glomerular filtration rate was 28.2 mL/min/1.73 m2 the urinary protein/ creatinine ratio was 154.2 mg/mmol, and CRP was 7.5 mg/L.

DISCUSSION

IRON-CKD will provide important information on the short-term effects of three preparations of IV iron in CKD patients with biochemical functional or absolute iron deficiency on measures of oxidative stress, inflammation, endothelial function, and renal injury.

TRIAL REGISTRATION

European Clinical Trials Database (EudraCT) number 2010-020452-64 .

Sources of lead exposure in various countries

This review evaluates the sources of lead exposure worldwide. Studies from searches relating to sources of lead exposure in various countries within different regional zones were reviewed. Results indicated that in Nigeria, exposure sources include electronic waste, paint and batteries. In Mexico exposure sources include glazed ceramics, lead contaminated utensils and lead contaminated water, for India lead sources include cosmetics and traditional medicines. Sources of lead exposure in China include e-waste, traditional medicines and industrial emissions. In France, exposure sources included lead paint from older homes, imported ceramics and cosmetics and industrial emissions. Australia's exposure sources include paint, dust, imported toys and traditional medicines. Finally, in the United States exposure sources included paint, the industrial legacy of lead exposure and batteries. In high-income countries (HICs) the legacy of lead exposure keeps populations continuously exposed. In lower- and middle-income countries (LMICs), in addition to the legacy of lead exposure, lack of regulations or the inability to enforce regulations keeps populations exposed. In all, evidence suggests that lead exposure remains an issue of public health significance in both HIC and LMIC.

Interactive Effects between Chronic Lead Exposure and the Homeostatic Iron Regulator Transport HFE Polymorphism on the Human Red Blood Cell Mean Corpuscular Volume (MCV)

Research has shown that long-term exposure to lead harms the hematological system. The homeostatic iron regulator HFE (hemochromatosis) mutation, which has been shown to affect iron absorption and iron overload, is hypothesized to be related to lead intoxication in vulnerable individuals. The aim of our study was to investigate whether the HFE genotype modifies the blood lead levels that affect the distributions of serum iron and other red blood cell indices. Overall, 121 lead workers and 117 unexposed age-matched subjects were recruited for the study. The collected data included the blood lead levels, complete blood count, serum iron, total iron binding capacity, transferrin, and ferritin, which were measured during regular physical examinations. All subjects filled out questionnaires that included demographic information, medical history, and alcohol and tobacco consumption. HFE genotyping for C282Y and H63D was determined using polymerase chain reaction and restriction fragment length polymorphism (PCR/RFLP). The mean blood lead level in lead workers was 19.75 µg/dL and was 2.86 µg/dL in unexposed subjects. Of 238 subjects, 221 (92.9%) subjects were wild-type (CCHH) for HFE C282Y and H63D, and 17 (7.1%) subjects were heterozygous for a H63D mutation (CCHD). Multiple linear regression analysis showed that blood lead was significantly negatively associated with hemoglobin (Hb), mean corpuscular hemoglobin concentration (MCHC), and mean corpuscular volume (MCV), whereas the HFE variant was associated negatively with MCV and positively with ferritin. An interactive influence on MCV was identified between blood lead and HFE variants. Our research found a significant modifying effect of the HFE variant, which possibly affected MCV. The HFE H63D heterozygous (CCHD) variant seemed to provide a protective factor against lead toxicity. Future studies should focus on competing binding proteins between iron and lead influenced by gene variation.

Heavy Metals in Sediments of Urban Streams: Contamination and Health Risk Assessment of Influencing Factors

Sediments of two urban streams in northern Poland outflowing to the Baltic Sea were assessed to explain the spatial variation in relation to urbanization level of the catchment, the role of retention tanks (RTs) and identification of pollution level. During the 3 month period of investigation sediment samples were collected from the inflow (IN) and outflow (OUT) of six RTs located on streams for flood protection. Six heavy metals (HMs) were investigated: Cu, Pb, Zn, Cd, Ni, Cr. The assessment of four geochemical enrichment indices used to quantify contamination of HMs in the sediments at IN and OUT samples was carried out. Contamination factor (CF), pollution load index (PLI), geoaccumulation index (Igeo) and potential ecological risk (RI) were calculated and the indices usefulness was assessed. Also, the hazard quotient (HQ) was calculated to assess health risk associated with dredging works. In sediments from RTs where paved surfaces constituted more than 70% of the catchment the HMs concentrations were from one to three times higher for Ni and from two to 143 times higher for Cu in comparison to soft catchment results. The extremely high Cu concentration (1114 mg/kg d.w.) found in sediments at RT Orłowska IN was most likely associated with large area of roofs covered with copper sheet. Calculation of CF, PLI, Igeo, RI, HQ indicators allows for a complex and multi-dimensional assessment of sediment status. Among these, CF and PLI classified the analyzed sediments as most polluted. Basing on the sedimentary HMs concentrations the health risk level via dermal exposure pathway was assessed as low.

Efficiency of the Air-Pollution Control System of a Lead-Acid-Battery Recycling Industry

The air-pollution control system of a lead-acid-battery recycling industry was studied. The system comprised two streams with gravity settlers followed by filter bags for the factory indoor air and the metal-recycling furnace, respectively. Efficiency in particle removal according to mass was found to be 99.91%. Moreover, filter bags and dust from the gravity settlers were analyzed for heavy metals by Wavelength Dispersive X-Ray Fluorescence. The results showed high concentrations of Pb and Na in all cases. In the filter bag samples from the indoor atmosphere stream, Ca, Cu, Fe, and Al were found in concentrations higher than that in the filter bag samples from the furnace stream. The opposite was found for Na. Tl and K were only found in furnace stream bag filters. The elemental concentration of the dust from the furnace fumes stream contained mainly Fe, Na, Cd, Pb, Sb, and Cl, while the indoor main stream contained mainly P, Fe, Na, Pb, and Sb. In all cases, impurities of Nd, Ni, Rb, Sr, Th, Hg, and Bi were found. The high efficiency of the air-pollution control system in particle removal shows that a considerable reduction in emissions was achieved.

Prospective associations between environmental heavy metal exposure and renal outcomes in adults with chronic kidney disease

AIM

In Taiwan, Changhua County residents were exposed to high heavy metal pollution and exhibited high heavy metal levels in blood and urine. We examined associations between heavy metals in residential soil and renal outcomes of residents with chronic kidney disease (CKD).

METHOD

From 1 January 2003 to 30 June 2015, we retrospectively identified CKD patients with an estimated glomerular filtration rate of <60 mL/min per 1.73 m² at one tertiary care centre. We linked data displaying heavy metal concentrations from farm soil adjacent to the patients' residences to clinical outcomes. We included 2343 CKD patients (533 with progression to end-stage renal disease [ESRD] and 1810 without]. We followed these patients for 3.49 ± 2.27 years, until death or initiation of maintenance dialysis.

RESULTS

There were high correlations among the concentrations of the eight metals: arsenic, cadmium, chromium, mercury, copper, lead, nickel, and zinc. After factor analysis, chromium, copper, nickel, and zinc were grouped and labelled Factor 1. High Factor 1 concentration near the patients' residences was associated with diagnoses of hypertension, diabetes mellitus, and cerebral vascular accident. Patients living in areas with high Factor 1 concentrations were at higher risk of ESRD. After multivariate adjustment [adjusted hazard ratio: 1.08, 95% Confidence interval: 1.01-1.14, P = 0.02], only zinc and nickel were risk factors for progression to ESRD.

CONCLUSION

Patients with CKD, with long-term exposure to soil-based heavy metals, had rapid progression to ESRD. Groups of minerals from the same source of contamination may accumulate and lead to additional harm.

Metabolic profiling of metformin treatment for low-level Pb-induced nephrotoxicity in rat urine

Chronic kidney disease is a worldwide problem, and Pb contamination is a potential risk factor. Since current biomarkers are not sensitive for the diagnosis of Pb-induced nephrotoxicity, novel biomarkers are needed. Metformin has both hypoglycaemic effects and reno-protection ability. However, its mechanism of action is unknown. We aimed to discover the early biomarkers for the diagnosis of low-level Pb-induced nephrotoxicity and understand the mechanism of reno-protection of metformin. Male Wistar rats were randomly divided into control, Pb, Pb + ML, Pb + MH and MH groups. Pb (250 ppm) was given daily via drinking water. Metformin (50 or 100 mg/kg/d) was orally administered. Urine was analysed by nuclear magnetic resonance (NMR)-based metabolomics coupled with multivariate statistical analysis, and potential biomarkers were subsequently quantified. The results showed that Pb-induced nephrotoxicity was closely correlated with the elevation of 5-aminolevulinic acid, D-lactate and guanidinoacetic acid in urine. After co-treatment with metformin, 5-aminolevulinic acid and D-lactate were decreased. This is the first demonstration that urinary 5-aminolevulinic acid, D-lactate and guanidinoacetic acid could be early biomarkers of low-level Pb-induced nephrotoxicity in rats. The reno-protection of metformin might be attributable to the reduction of D-lactate excretion.

Is There a Relationship between Lead Exposure and Aggressive Behavior in Shooters?

Lead exposure has been associated with psycho-neurological disorders. Elevated blood lead levels have been found in shooters. This study assesses the association between the blood lead levels of shooters and their levels of aggression. An analytical cross-sectional study was conducted in Gauteng, South Africa. Participants were recruited from four randomly selected shooting ranges with three randomly selected archery ranges used as a comparison group. A total of 118 (87 shooters and 31 archers) participants were included in the analysis. Aggressiveness was measured using the Buss-Perry Aggression Questionnaire. Shooters had significantly higher blood lead levels (BLL) compared to archers with 79.8% of shooters versus 22.6% of archers found to have a BLL ≥ 5 μg/dL (p < 0.001). Aggression scores were significantly higher in shooters (p < 0.05) except for verbal aggression. In the bivariate and regression analyses, shooters with BLLs ≥ 10 μg/dL were significantly associated with the hostility sub-scale (p = 0.03, adjusted odds ratio (OR) 2.83, 95% confidence interval (CI) 1.103–7.261). Shooters have a significantly higher BLL and aggressiveness compared to archers. However, elevated blood lead levels were significantly associated with hostility only. Interventions need to be put in place to prevent continued exposure and routine screening of populations at risk should be implemented.

Chronic Toxic Metal Exposure and Cardiovascular Disease: Mechanisms of Risk and Emerging Role of Chelation Therapy

Over the last few decades, there has been a growing body of epidemiologic evidence linking chronic toxic metal exposure to cardiovascular disease-related morbidity and mortality. The recent and unexpectedly positive findings from a randomized, double-blind, multicenter trial of metal chelation for the secondary prevention of atherosclerotic cardiovascular disease (Trial to Assess Chelation Therapy (TACT)) have focused the discussion on the role of chronic exposure to toxic metals in the development and propagation of cardiovascular disease and the role of toxic metal chelation therapy in the secondary prevention of cardiovascular disease. This review summarizes the most recent evidence linking chronic toxic metal exposure to cardiovascular disease and examines the findings of TACT.

Blood lead level is a positive predictor of uremic pruritus in patients undergoing hemodialysis

Although uremic pruritus (UP) is a common and annoying symptom for end-stage renal disease patients on hemodialysis (HD) and peritoneal dialysis, its pathogenesis is poorly understood. However, systemic inflammation is one of the possible pathogenesis of UP, and blood lead level (BLL) has been noted to be associated with inflammation and nutritional status in long-term HD patients. There might be an interaction or association, therefore, between BLL and UP through systemic inflammation. We analyzed cross-sectional data among 866 participants. All of the 866 patients in this study were stratified into groups with low-normal (<10 μg/dL), high-normal (10-20 μg/dL), and abnormal BLLs (>20 μg/dL). The associations between UP and BLL and the clinical data were analyzed. Multivariate logistic regression demonstrated that HD duration, non-anuria, log ferritin, serum low-density lipoprotein, log BLL, high-normal BLL, and high BLL were associated with UP. In conclusion, BLL was positively associated with UP.