The references level of cadmium intake for renal dysfunction in a Chinese population

Estimation of urinary cadmium benchmark dose thresholds for preschool children in a cadmium-polluted area based on Bayesian model averaging

Urinary cadmium (U-Cd) values are indicators for determining chronic cadmium toxicity, and previous studies have calculated U-Cd indicators using renal injury biomarkers. However, most of these studies have been conducted in adult populations, and there is a lack of research on U-Cd thresholds in preschool children. We aimed to apply benchmark dose (BMD) analysis to estimate the U-Cd threshold level associated with renal impairment in preschool children in the cadmium-polluted area. 518 preschool children aged 3-5 years were selected by systematic sampling (275 boys, 243 girls). Urinary cadmium and three biomarkers of early renal injury (urinary N-acetyl-β-D-glucosaminidase, UNAG; urinary β2-microglobulin, Uβ2-MG; urinary retinol-binding protein, URBP) were determined. Bayesian model averaging estimated the BMD and lower confidence interval limit (BMDL) of U-Cd. The medians U-Cd levels in both boys and girls exceeded the recommended national standard threshold (5 μg/g cr) and U-Cd levels were higher in girls than in boys. Urinary N-acetyl-β-D-glucosaminidase (UNAG) was the most sensitive biomarker of renal effects in preschool children. The overall BMDL5 (BMDL at a benchmark response value of 5) was 2.76 μg/g cr. In the gender analysis, the BMDL5 values were 1.92 μg/g cr for boys and 4.12 μg/g cr for girls. This study shows that the U-Cd threshold (BMDL5) is lower than the national standard (5 μg/g cr) and boys' BMDL5 was lower than the limit set by the European Parliament and Council in 2019 (2 μg/g cr), which provides a reference point for making U-Cd thresholds for preschool children.

Spatio-temporal distribution of cadmium levels in Chinese population and its potential risk factors

Cadmium (Cd), a ubiquitous heavy metal, exists in numerous environmental matrices and has severe adverse effects on various human organs and tissues. This research evaluates blood and urine Cd levels in the Chinese population through data mining using Monte Carlo simulation (MCS). A total of 168 scientific studies (120 on urine and 48 on blood) published between January 1980 and December 2020, reflecting a population of 109,743 individuals in China, were included in the study. The results indicate that the blood and urine Cd levels in the Chinese population exhibited a peak from 1990 to 1995 and remained stable after 1995, averaging 1.21 μg/L of blood Cd (BCd) and 0.61 μg/L of urine Cd (UCd). The spatial trend of Cd levels varied significantly. Shandong, Zhejiang, Heilongjiang, and Guangdong provinces were identified as the top provinces with high Cd levels, which were related to factors such as tobacco sales, E-waste amounts, and contaminated rice. Additionally, the study highlights that BCd concentrations are highest among preschool-aged individuals, whereas school-age and adolescent groups exhibit the lowest levels. However, no significant difference existed among the different age groups. Males showed significantly higher Cd levels than females in the general population. Moreover, exposure to smoking, drinking, and staple food preferences had an impact on Cd levels. Furthermore, this comprehensive study, using biological monitoring and data mining, provides valuable information on Cd pollution levels in the Chinese population. It presents a statistical analysis that can aid decision-makers in implementing effective measures to control potential Cd pollution and improve the health of vulnerable populations.

Effects of cadmium exposure during pregnancy on genome-wide DNA methylation and the CREB/CREM pathway in the testes of male offspring rats

This experimental study explored the multigenerational and transgenerational effects of cadmium (Cd) exposure during pregnancy on the testicular tissue and spermatogenesis of male offspring rats. CdCl2 at different doses (0, 0.5, 1, 2 mg/kg/day) were dispensed to pregnant SD rats, thus producing generation F1. Adult females in F1 (PND 56) were mated with untreated fertile males so as to produce generation F2. Likewise, adult females in F2 were mated to produce generation F3. Damages to testicular tissue were observed in all the three generations, with serum testosterone (T) increased in F2 and F3. Notably, the genome-wide DNA methylation level in the testicular tissue of F1 was altered, as was the expression of F1-F3 methyltransferases. In addition, the expression of Creb/Crem pathway, a pathway critical for the metamorphosis from postmeiotic round spermatocytes to spermatozoa, was also remarkably altered in the three generations. In concludion, prenatal Cd exposure might bring multigenerational and transgenerational toxic effects to testes via genome-wide DNA methylation and the regulation of CREB/CREM pathway.

Fabrication and Arc Erosion Behavior of Ag-SnO2-ZnO Electrical Contact Materials

This study investigated the synthesis of Ag-SnO₂-ZnO by powder metallurgy methods and their subsequent electrical contact behavior. The pieces of Ag-SnO₂-ZnO were prepared by ball milling and hot pressing. The arc erosion behavior of the material was evaluated using homemade equipment. The microstructure and phase evolution of the materials were investigated through X-ray diffraction, energy-dispersive spectroscopy and scanning electron microscopy. The results showed that, although the mass loss of the Ag-SnO₂-ZnO composite (9.08 mg) during the electrical contact test was higher than that of the commercial Ag-CdO (1.42 mg), its electrical conductivity remained constant (26.9 ± 1.5% IACS). This fact would be related to the reaction of Zn₂SnO₄'s formation on the material's surface via electric arc. This reaction would play an important role in controlling the surface segregation and subsequent loss of electrical conductivity of this type of composite, thus enabling the development of a new electrical contact material to replace the non-environmentally friendly Ag-CdO composite.

A systematic review of adverse health effects associated with oral cadmium exposure

Scientific data characterizing the adverse health effects associated with dietary cadmium (Cd) exposure were identified in order to make informed decisions about the most appropriate toxicological reference value (TRV) for use in assessing dietary Cd exposure. Several TRVs are available for Cd and regulatory organizations have used epidemiologic studies to derive these reference values; however, risk of bias (RoB) evaluations were not included in the assessments. We performed a systematic review by conducting a thorough literature search (through January 4, 2020). There were 1714 references identified by the search strings and 328 studies identified in regulatory assessments. After applying the specific inclusion and exclusion criteria, 208 studies (Human: 105, Animal: 103) were considered eligible for further review and data extraction. For the epidemiologic and animal studies, the critical effects identified for oral Cd exposure from the eligible studies were a decrease in bone mineral density (BMD) and renal tubular degeneration. A RoB analysis was completed for 49 studies (30 epidemiological and 19 animal) investigating these endpoints. The studies identified through the SR that were considered high quality and low RoB (2 human and 5 animal) can be used to characterize dose-response relationships and inform the derivation of a Cd TRV.

Heavy metals exposure is associated with early liver dysfunction among rural residents aged 40-75 years in southwest China

Heavy metals exposure has been associated with liver dysfunction in recent reports, while the hepatoxicity of lead (Pb) and cadmium (Cd) has been well established. However, the combined effects of multi-metal in real-world scenario on liver dysfunction are still unclear. This cross-sectional study examined associations between 10 biomarkers of early liver injury and multiple heavy metals levels. The levels of heavy metals/metalloid (magnesium [Mg], calcium [Ca], iron [Fe], zinc [Zn], arsenic [As], Cd, copper [Cu], and Pb) were measured in blood and urinary sample collected from 725 participants in a Cd-polluted area and an unpolluted area in southwest China. The early liver dysfunction biomarkers included the liver enzymes (ALT, ALP, AST, and GGT), proteins (TP, ALB, and GLO), and bilirubin (TBIL, DBIL, and IBIL). Confounder-adjusted beta coefficients were determined using multiple linear regression model analysis for the group-classified and gender-classified samples. Our results showed that blood Fe, Cd, and Cu levels were found to be positively related to elevated ALT levels and blood Cu was positively associated with AST levels in the Cd-polluted area, while the highest blood Zn quartile in the polluted area and blood Mg quartile in the unpolluted area were associated with lower ALT levels. Our finding implies that industrial pollution results in heavy metals of Cd and Pb exposure and effects of Fe, Cd, Cu, and Pb in the Cd-polluted area may be the main contributors to increase the risk of liver dysfunction while Zn in the Cd-polluted area and Mg in the unpolluted area may be the protective factors.

Anti-BCMA CAR-T Cell Therapy in Relapsed or Refractory Multiple Myeloma Patients with Impaired Renal Function

Anti-B cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T-cell therapy is effective and well-tolerated for refractory or relapsed multiple myeloma (RRMM). The purpose of the present study was to analyze efficacy in RRMM patients with renal impairment treated by anti-BCMA CAR-T cell therapy. A total of 59 RRMM patients were selected, and divided into impaired renal function (IRF) group [baseline estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73 m² (n=18)] and normal renal function (NRF) group (baseline eGFR ≥ 90 mL/min/1.73 m², n=41). For patients with IRF, eGFR at the 6th month post-CAR-T cells infusion was significantly higher than the baseline (P<0.05). The multivariate analysis showed that light chain type and beta-2 micro-globulin (beta-2M) were associated factors with the decrease of serum creatinine. Median progression-free survival (PFS) in the NRF group and IRF group was 266 days and 181 days respectively. Overall survival (OS) in the NRF group and IRF group was 877 days and 238 days respectively. There was no significant difference in the objective response rate (ORR) between the IRF group and the NRF group. It is suggested that CAR-T cells therapy could improve the renal function during the treatment of RRMM. The renal function could be more significantly improved in RRMM patients with light chain type than with other types.

Environmental cadmium exposure induces kidney tubular and glomerular dysfunction in the Myanmar adults

Cadmium is an environmental toxic metal and its exposure has become a worldwide public health threat. We aimed to evaluate the exposure assessment of cadmium in people living in Ta Zin Yae Kyaw village of Nyaung Don Township in Ayeyarwady Division, Myanmar and adverse effects of cadmium on the kidneys. Subjects (18-40 years) residing in this village were selected as the exposed group (n = 65) and those living in Kamayut Township in Yangon Division, Myanmar as the control group (n = 65). Spot urine samples were taken for determination of urinary cadmium concentration using graphite-furnace atomic absorption spectrometry (GFAAS) method and adjusted to the concentration of creatinine in urine. To assess the kidney function, urinary β₂-microglobulin level was determined by ELISA, serum creatinine was measured by colorimetric Jaffe method and estimated glomerular filtration rate (eGFR) was calculated by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Urine cadmium concentrations were significantly higher in the exposed group (median (Interquartile range): 0.96 (0.19-1.77) μg/g Creatinine) compared to the control (p = 0.036). Urinary β₂-microglobulin levels were significantly higher (p = 0.000) and eGFR was significantly lower in the exposed group (p = 0.013) compared to the control. In addition, urine cadmium level showed significant positive correlation with urinary β₂-microglobulin in all study population (p < 0.01). Positive correlation becomes stronger (p < 0.01) in the exposed group only. For eGFR, significant negative correlation was found in all study population (p < 0.01) and exposed group (p < 0.01). Our findings suggested that environmental cadmium exposure can induce renal dysfunction in both tubular and glomerular functions in apparently healthy human adults.

Risks of consuming cadmium-contaminated shellfish under seawater acidification scenario: Estimates of PBPK and benchmark dose

We aim to assess the risks of renal dysfunction and osteoporosis that is attributed to the seawater acidification caused cadmium (Cd) level increase in human consumed shellfish. A physiology-based pharmacokinetic model was used to estimate Cd concentrations in urine and blood among shellfish-only consumers and among the general population. We used the benchmark dose (BMD) method to determine the threshold limits of Cd in urine for renal dysfunction and in blood for osteoporosis for assessing the human health risk. Our results revealed that seawater acidification could increase the Cd accumulation in shellfish by 10-13% compared to the situations under current pH levels. Under the lower seawater pH level, the daily intake of Cd could increase by 21%-67% among shellfish-only consumers, and by 13%-17% among the general population. Our findings indicated that seawater acidification would lead to a marginal increase in Cd intake among humans in shellfish-only consumers. The results of BMDs of urinary Cd showed that the threshold limits for renal dysfunction at 5% were 3.00 μg g^-1 in males and 12.35 μg g^-1 in females. For osteoporosis, the estimated BMDs of blood Cd were 7.95 μg L^-1 in males and 1.23 μg L^-1 in females. These results of the risk of Cd intake showed that the consumption of Cd-contaminated shellfish in the general population is largely unaffected by changes in seawater pH levels. Notably, the potential impact of seawater acidification on renal dysfunction for males in shellfish-only consumers face a 14% increase of risk.

Blood BTEXS and heavy metal levels are associated with liver injury and systemic inflammation in Gulf states residents

INTRODUCTION

Exposures to volatile organic compounds and metals have previously been associated with liver diseases including steatohepatitis, although more data are needed. Benzene, toluene, ethylbenzene, xylenes, styrene (BTEXS) and metals were measured in blood samples collected between May 2012-July 2013 from volunteers participating in home visits for the Gulf Long-term Follow-up (GuLF) Study. This cross-sectional analysis evaluates associations of exposure biomarkers with serum liver injury and adipocytokine biomarkers in a sample of 214 men.

METHODS

Adult nonsmoking men without a history of liver disease or heavy alcohol consumption were included. The serologic disease biomarkers evaluated were the hepatocellular injury biomarker, cytokeratin 18 [whole (CK18 M65) and caspase-cleaved fragment (CK18 M30)]; and adipocytokines. Confounder-adjusted beta coefficients were determined using linear regression models for the overall sample (primary endpoints) and for obesity-classified sub-groups (secondary endpoints). A product interaction term between the exposure of interest and a dichotomized indicator of obesity was included to determine the disease modifying effects of obesity on the biomarker associations.

RESULTS

The study sample was 57% white and 51% obese. In the overall sample, lead was positively associated with CK18 M30 (β = 21.7 ± 6.0 (SE), p = 0.0004); IL-1β (β = 32.8 ± 5.2, p < 0.0001); IL-6 (β = 72.8 ± 18.3, p = 0.0001); and IL-8 (β = 140.8 ± 42.2, p = 0.001). Cadmium exposures were associated with increased IL-1β (β = 77.8 ± 26.3, p = 0.003) and IL-8 (β = 419.5 ± 201.2, p = 0.04). There were multiple significant interactions between obesity and exposure to lead, cadmium, benzene and toluene in relation to outcome biomarkers. Among obese participants (n = 108), benzene, lead, and cadmium were each positively associated with CK18 M30, IL-1β, IL-6, and IL-8. In obese subjects, lead was also inversely associated with leptin, and toluene was positively associated with IL-1β.

CONCLUSION

For the overall sample, heavy metal exposures were associated with liver injury (lead only) and/or systemic inflammation (lead and cadmium). Obesity modified the associations between BTEXS and heavy metal exposures on several of the outcome variables. In the obesity subgroup, liver injury was positively associated with lead, cadmium and benzene exposures; systemic inflammation was increased with lead, cadmium, benzene, and toluene exposures; and leptin was inversely associated with lead exposures. The cross-sectional design of this study makes it difficult to determine causality, and all results should be interpreted cautiously. Nonetheless, the potential impact of exposures to lead, cadmium, benzene and toluene in steatohepatitis, an obesity-associated inflammatory liver disease, warrants further investigation.

The inverse association of glomerular function and urinary β2-MG excretion and its implications for cadmium health risk assessment

Urinary β2-microgroblin (β2-MG) excretion levels above 300 μg/g creatinine are used to indicate defective tubular reabsorption. Arguably, increased urinary β2-MG excretion could also reflect glomerular filtration rate decline. Thus, we investigated an association between urinary β2-MG and estimated glomerular filtration rate (eGFR). We studied 527 subjects, aged 30-87 years (mean 51.2), who lived in a rural area of Thailand polluted with cadmium (Cd). Of this cohort, 10.3% had urinary Cd levels <2 μg/g creatinine and 53.5% had urinary Cd levels ≥5 μg/g creatinine. Half (53.1%) of the participants had urinary β2-MG levels ≥ 300 μg/g creatinine, and 11.6% had low GFR, defined as eGFR <60 mL/min/1.73 m². Lower eGFR values were associated with older age (β = -0.568, P < 0.001), higher urinary β2-MG (β = -0.170, P < 0.001), higher urinary Cd (β = -0.103, P = 0.005) and diabetes (β = 0.074, P = 0.032). An inverse association between eGFR and urinary β2-MG was evident in subjects with low GFR (β = -0.332, P = 0.033), but not in those with GFR >90 mL/min/1.73 m² (β = -0.008, P = 0.896). These findings suggested Cd-induced nephron loss and reduced tubular reabsorption in low eGFR subjects. Urinary β2-MG levels <300 μg/g creatinine were associated with 4.66 (95% CI: 1.92, 11.32) fold increase in the POR for low GFR, compared with urinary β2-MG levels <100 μg/g creatinine. Findings in the present study cast doubt on a cut-off value for urinary β2-MG, while lending support to the notion that elevated urinary β2-MG excretion could indicate a fall of GFR.