Adverse health effects of chronic exposure to low-level cadmium in foodstuffs and cigarette smoke

Systematic review and meta-analysis links autism and toxic metals and highlights the impact of country development status: Higher blood and erythrocyte levels for mercury and lead, and higher hair antimony, cadmium, lead, and mercury

BACKGROUND

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder that affects cognitive and higher cognitive functions. Increasing prevalence of ASD and high rates of related comorbidities has caused serious health loss and placed an onerous burden on the supporting families, caregivers, and health care services. Heavy metals are among environmental factors that may contribute to ASD. However, due to inconsistencies across studies, it is still hard to explain the association between ASD and toxic metals. Therefore the objective of this study was to investigate the difference in heavy metal measures between patients with ASD and control subjects.

METHODS

We included observational studies that measured levels of toxic metals (antimony, arsenic, cadmium, lead, manganese, mercury, nickel, silver, and thallium) in different specimens (whole blood, plasma, serum, red cells, hair and urine) for patients with ASD and for controls. The main electronic medical database (PubMed and Scopus) were searched from inception through October 2016.

RESULTS

52 studies were eligible to be included in the present systematic review, of which 48 studies were included in the meta-analyses. The hair concentrations of antimony (standardized mean difference (SMD)=0.24; 95% confidence interval (CI): 0.03 to 0.45) and lead (SMD=0.60; 95% confidence interval (CI): 0.17 to 1.03) in ASD patients were significantly higher than those of control subjects. ASD patients had higher erythrocyte levels of lead (SMD=1.55, CI: 0.2 to 2.89) and mercury (SMD=1.56, CI: 0.42 to 2.70). There were significantly higher blood lead levels in ASD patients (SMD=0.43, CI: 0.02 to 0.85). Sensitivity analyses showed that ASD patients in developed but not in developing countries have lower hair concentrations of cadmium (SMD=-0.29, CI: -0.46 to -0.12). Also, such analyses indicated that ASD patients in developing but not in developed lands have higher hair concentrations of lead (SMD=1.58, CI: 0.80 to 2.36) and mercury (SMD=0.77, CI: 0.31 to 1.23). These findings were confirmed by meta-regression analyses indicating that development status of countries significantly influences the overall effect size of mean difference for hair arsenic, cadmium, lead, and mercury between patients with ASD and controls.

CONCLUSION

The findings help highlighting the role of toxic metals as environmental factors in the etiology of ASD, especially in developing lands. While there are environmental factors other than toxic metals that greatly contribute to the etiology of ASD in developed lands. It would be, thus, expected that classification of ASD includes etiological entities of ASD on the basis of implication of industrial pollutants (developed vs. developing ASD).

A protective role of Heme-regulated eIF2α kinase in cadmium-induced liver and kidney injuries

A number of studies have reported that cadmium (Cd) can incur liver and kidney injuries. The recruitment and activation of leukocytes have been demonstrated to be involved in Cd-induced biological effects. Ironically, activated leukocytes and secreted cytokines are also reported to be required for the later recovery of the damaged tissues. Yet, the mechanisms driving the production of leukocytes have not been fully elucidated. Heme-regulated eIF2α kinase (HRI) is essential for translational regulation and stressed erythropoiesis in iron deficiency. Meanwhile, HRI is important in the maturation and function of macrophages, indicating that HRI might be indispensable for the development and function of other myeloid lineages. Apart from macrophages, whether HRI regulates the production of leukocytes and further affects Cd-induced tissue injuries is still elusive. In this study, we aimed to elucidate the role of HRI in liver and kidney injuries and the associated mechanisms upon Cd exposure. We found that Cd-exposed mice showed impaired production of leukocytes and developed morphological disorders in liver and kidney. Furthermore, Hri null mice exhibited a reduced number of monocytes and neutrophils and compromised cytokine production, relative to wild-type mice. Absence of Hri also exacerbated the impairments of liver and kidney upon Cd treatment. Together, these results highlighted a crucial role of HRI in protecting liver and kidney against Cd-induced injuries through inducing the development of monocytes and neutrophils. Our results further extended the understanding of HRI on the regulation of non-erythroid lineages and might provide new aspects for preventing and treating Cd-induced detrimental effects.

Cadmium Exposure and Osteoporosis: A Population-Based Study and Benchmark Dose Estimation in Southern China

This study aimed to assess the association between osteoporosis and long-term environmental Cd exposure through diet in southern China. A total of 1116 subjects from a Cd-polluted area and a non-Cd-polluted area were investigated. All subjects met the criteria of having been living in the investigated area for more than 15 years and lived on a subsistence diet of rice and vegetables grown in that area. Besides bone mineral density, the levels of urinary markers of early renal impairment, such as urinary N-acetyl-β-D-glucosaminidase (NAG), α₁ -microglobulin, β₂ -microglobulin, and urinary albumin, were also determined. Urinary Cd concentrations of all studied subjects ranged from 0.21 to 87.31 µg/g creatinine, with a median of 3.97 µg/g creatinine. Multivariate linear regression models indicated a significant negative association of urinary Cd concentrations with bone mineral density. In logistic regression models, both categorical and continuous urinary Cd concentrations were positively associated with osteoporosis. Subjects in the second, third, and fourth quartiles of urinary Cd concentration had greater odds of osteoporosis compared with subjects in the first quartile (odds ratio [OR] = 3.07, 95% confidence interval [CI], 1.77 to 5.33; OR = 4.63, 95% CI, 2.68 to 7.98; OR = 9.15, 95% CI, 5.26 to 15.94, respectively). Additional adjustment for levels of urinary markers did not attenuate the associations. No evidence existed of an interaction between urinary Cd concentration and renal function using levels of urinary markers, and estimated glomerular filtration rate (eGFR). In all subjects, the benchmark dose and benchmark dose lower bound were 1.14 (0.61) and 2.73 (1.83) µg/g creatinine, with benchmark response set at 5% and 10%, respectively. The benchmark dose of urinary Cd was lower in women than in men. This study demonstrated an inverse association between the body burden of Cd and osteoporosis. The toxic effect of Cd on bone may occur in parallel to nephrotoxicity. © 2017 American Society for Bone and Mineral Research.

Maternal exposure to selenium and cadmium, fetal growth, and placental expression of steroidogenic and apoptotic genes

BACKGROUND

Cadmium (Cd) and selenium (Se) antagonistically influence redox balance and apoptotic signaling, with Cd potentially promoting and Se inhibiting oxidative stress and apoptosis. Alterations to placental redox and apoptotic functions by maternal exposure to Cd and Se during pregnancy may explain some of the Cd and Se associations with fetal development.

OBJECTIVES

Investigate associations between Cd and Se concentrations in maternal toenails with placental expression patterns of tumor necrosis factor (TNF) and steroidogenic genes involved in redox reactions and test associations with fetal growth.

METHODS

In a sub-sample from the Rhode Island Child Health Study (n = 173), we investigated the relationships between: (1) maternal toenail Cd and Se concentrations and fetal growth using logistic regression, (2) Cd and Se interactions with factor scores from placental TNF and steroidogenic expression patterns (RNAseq) using linear models, and (3) TNF and steroidogenic expression factors with fetal growth via analysis of covariance.

RESULTS

Se was associated with decreased odds of intrauterine growth restriction (IUGR) (OR = 0.27, p-value = 0.045). Cd was associated with increased odds of IUGR (OR = 1.95, p-value = 0.13) and small for gestational age (SGA) births (OR = 1.46, p-value = 0.11), though not statistically significant. Cd and Se concentrations were antagonistically associated with placental TNF and steroidogenic expression patterns, which also differed by birth size.

CONCLUSIONS

Se may act as an antagonist to Cd and as a modifiable protective factor in fetal growth restriction, and these data suggest these effects may be due to associated variations in the regulation of genes involved in placental redox balance and/or apoptotic signaling.

The longitudinal effects of early developmental cadmium exposure on conditioned place preference and cardiovascular physiology in zebrafish

Cadmium (Cd) is a naturally occurring trace metal that is widely considered to be highly toxic to aquatic organisms and a significant health hazard to humans (Amzal et al., 2009; Bernhoft 2013; Burger, 2008; Satarug et al., 2009). The zebrafish (Danio rerio) has been used as a model organism for toxicological studies with Cd (Banni et al., 2011; Blechinger et al., 2007; Chow et al., 2009; Chow et al., 2008; Favorito et al., 2011; Kusch et al., 2007; Matz et al., 2007; Wang and Gallagher, 2013). We asked what the lasting longitudinal effects would be from short early developmental Cd exposure (between 24 and 96h post-fertilization) in a range that larvae might experience living atop typical Cd-containing surface sediments (0, 0.01, 0.1, 1.0 and 10μM CdCl2: 1.124, 11.24, 112.4 and 1124μg Cd/L). The goal of this exposure window was to specifically target secondary neurogenesis, monoaminergic differentiation and cardiovascular development, without affecting earlier patterning processes. Developmental abnormalities in body size and CNS morphology increased with concentration, but were statistically significant only at the highest concentration used (10μM). Heart rate for Cd-treated larvae increased with concentration, and was significant even at the lowest concentration used (0.01μM). Longitudinal survival was significantly lower for fish developmentally exposed to the highest concentration. Except for brain weight, overall morphology was not affected by developmental Cd exposure. However, developmental exposure to lower concentrations of Cd (0.01, 0.1, and 1.0μM) progressively lowered cocaine-induced conditioned place preference (CPP), used to measure function of the reward pathways in the brain. Baseline heart rate was significantly lower in longitudinal fish developmentally exposed to 1.0μM Cd. Cardiovascular response to isoproterenol, a potent ß-adrenergic agonist, in longitudinal adults was also significantly affected by developmental exposure to Cd at low doses (0.01, 0.1 and 1.0μM). Surviving longitudinal adult fish exposed to the highest concentration of Cd showed normal CPP and cardiovascular physiology. The data imply that even lower exposure concentrations can potentially result in fitness-affecting parameters without affecting survival in a laboratory setting.

Metabolomics study of cadmium-induced diabetic nephropathy and protective effect of caffeic acid phenethyl ester using UPLC-Q-TOF-MS combined with pattern recognition

Diabetic nephropathy (DN) is the most severe complication of diabetes and multiple factors are involved in the pathogenesis of DN. Among them, cadmium (Cd) acts as a risk factor inducing the occurrence of DN. The present study focused on investigating the protective role of caffeic acid phenethyl ester (CAPE), an active component of propolis from honeybee hives, against Cd-induced DN in mice based on ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS)and pattern recognition. Serum and urine biochemical indexes were detected and histopathological observation has been done to evaluate the damage of Cd on animals. Moreover, the global serum profiles of different groups were distinguished by UPLC-Q-TOF-MS and principal component analysis (PCA) were applied for group differentiation and marker selection. Moreover, the influence of Cd on the oxidative status in DN mice were also evaluated by assessing the parameters of oxidative stress, proinflammatory cytokines and antioxidant competence. As shown in the scores plots, the distinct clustering among controls, DN and CAPE groups were observed, significant changes in serum levels of LysoPC(18:1(11Z)), 2,3-dinor-8-iso-PGF2a, PS(18:1(9Z)/18:1(9Z)), DG(17:0/22:4 (7Z,10Z, 13Z, 16Z)/0:0) and Arachidonic acid(AA) were noted and identified as potential biomarkers, the effect of CAPE reverted them back to near normalcy. Further, It was observed a significant improvement in lipid peroxides (LPO) and protein carbonyls (PCO) levels in Cd-induced DN kidneys along with a significant decline in superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) levels, however, CAPE relieved these changes. In conclusion, the study suggested that the pathogenesis of DN caused by Cd probably owes to the perturbations of lipid metabolism and AA metabolism; CAPE seems to be effective agent and may be related to its potent antioxidant, anti-inflammatory properties and action as an Nrf2 activator.

Prenatal cadmium exposure and preterm low birth weight in China

Early studies have investigated the effect of prenatal cadmium (Cd) exposure on birth outcomes, such as preterm birth and low birth weight, although the results of these studies are inconsistent. The aim of the present study was to investigate the association between prenatal exposure to Cd and the risk of preterm low birth weight (PLBW). A total of 408 mother-infant pairs (102 PLBW cases and 306 pair matched controls) were selected from the participants enrolled in the Healthy Baby Cohort (HBC) study between 2012 and 2014 in Hubei province, China. Concentrations of Cd in maternal urine collected before delivery were measured by inductively coupled plasma mass spectrometry and adjusted by creatinine. A significant association was observed between higher maternal urinary Cd levels and risk of PLBW (adjusted odds ratio (OR)=1.75 for the medium tertile, 95% confidence interval (CI): 0.88, 3.47; adjusted OR=2.51 for the highest tertile, 95% CI: 1.24, 5.07; P trend=0.03). The association was more pronounced among female infants than male infants. Our study suggested that prenatal exposure to Cd at the current level encountered in China may potentially increase the risk of delivering PLBW infants, particularly for female infants.

Relation of rice intake and biomarkers of cadmium for general population in Korea

Environmental exposure to cadmium can cause renal damage. Foods containing cadmium are generally regarded as the main environmental sources of human exposure to cadmium. In this study, foods that are ingested in large amounts, including rice and other types of food with a high concentration of cadmium, were investigated to determine the correlation between the foods' cadmium content and biomarkers. The datasets required for this study, including blood cadmium concentration, biomarker concentration, and data on the amount of consumption by food item, were obtained from KNHNES. Furthermore, data on food groups with high daily exposure to hazardous amounts of cadmium were obtained by monitoring raw food sources from 2010 to 2012. The investigation was then followed by correlation analysis, which was performed to assess the relationship between the amount of rice consumption and cadmium concentration. The Pearson coefficient analysis on the relationship between the amount of food consumption and the biomarker showed that the correlation between foods' cadmium content and blood cadmium and that of between foods' cadmium content and other biomarkers were confirmed as statistically significant in the case of the cadmium content of white rice, while, in the case of brown rice, it was confirmed by a few biomarkers.

Selenium protects against cadmium-induced kidney apoptosis in chickens by activating the PI3K/AKT/Bcl-2 signaling pathway

Cadmium (Cd) is a toxic heavy metal that can induce apoptosis. Selenium (Se) is a necessary trace element and can antagonize the toxicity of many heavy metals, including Cd. PI3K/AKT/Bcl-2 is a key survival signaling pathway that regulates cellular defense system against oxidative injury as well as cell proliferation, survival, and apoptosis. The antagonistic effects of Se on Cd-induced toxicity have been reported. However, little is known about the effect of Se on Cd-induced apoptosis in chicken kidneys via the PI3K/AKT/Bcl-2 signaling pathway. In the present study, we fed chickens with Se, Cd, or both Se and Cd supplements, and after 90 days of treatment, we detected the related index. The results showed that the activity of inducible nitric oxide synthase (iNOS) and concentration of nitric oxide (NO) were increased; activities of the mitochondrial respiratory chain complexes (complexes I, II, and V) and ATPases (the Na⁺-K⁺-ATPase, the Mg²⁺-ATPase, and the Ca²⁺-ATPase) were decreased; expression of PI3K, AKT, and Bcl-2 were decreased; and expression of Bax, Bak, P53, Caspase-3, Caspase-9, and cytochrome c (Cyt c) were increased. Additionally, the results of the TUNEL assay showed that the number of apoptotic cells was increased in the Cd group. By contrast, there was a significant improvement of the correlation indicators and occurrence of apoptosis in the Se + Cd group compared to the Cd group. In conclusion, our results confirmed that Se had a positive effect on ameliorating Cd-induced apoptosis in chicken kidney tissue by activating the PI3K/AKT/Bcl-2 signaling pathway.

Serum levels of lead, mercury and cadmium in relation to coronary artery disease in the elderly: A cross-sectional study

BACKGROUND

There is a continuing attempt to identify novel factors that can predict the risk of cardiovascular disease beyond the established coronary risk factors. It has been suggested that serum levels of lead, mercury and cadmium are associated with the risk of coronary artery disease (CAD). In the present study, we aimed to evaluate serum concentrations of lead (s-Pb), mercury (s-Hg) and cadmium (s-Cd) in patients with CAD in comparison with those of healthy individuals. The correlation between serum levels of these heavy metals and lipid profile parameters was also investigated.

METHODS

In this case-control study, we included 65 patients (35 females) aged 50-70 years with angiographically-documented CAD and 65 healthy controls (43 female) matched for sex, age and place of residence. Serum concentrations of heavy metals were determined using graphite furnace atomic absorption (GFAA). Serum lipids were measured using routine enzymatic methods.

RESULTS

It was observed that the mean concentration of s-Pb (12.54 ± 8.41 vs. 5.89 ± 4.44 μg/L, p < 0.05) and s-Cd (0.938 ± 0.72 vs. 0.448 ± 0.30, p < 0.05; CI: 95%) and s-Hg (10.14 ± 5.06 vs. 6.11 ± 5.66, p < 0.05) were significantly higher in CAD patients compared with control subjects. The same result was also obtained after adjustment for cardiovascular risk factors including age, dyslipidemia, diabetes mellitus and hypertension (p < 0.05). The mean concentration of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and TC:HDL-C ratio were significantly higher in CAD patients (p < 0.05). There was no significant association between serum metal concentrations with TC, HDL-C and TC:HDL-C ratio (p > 0.05).

CONCLUSIONS

The present results showed that serum levels of heavy metals are associated with the presence of CAD. Long-term exposure to trace levels of Pb, Cd and Hg may play a role in the development of coronary atherosclerotic plaques.

Cadmium, lead and mercury concentrations in pathologically altered human kidneys

Heavy metals, including cadmium (Cd), lead (Pb) and mercury (Hg) act as nephrotoxic agents, particularly in the renal cortex. The aim of the study was to determine the concentrations of Cd, Pb and Hg in kidneys removed from patients due to lesions of various etiologies and from patients after the rejection of transplanted kidneys. Additionally, we determined the influence of selected biological and environmental factors on the concentrations of toxic metals. The study material consisted of kidneys with tumor lesions (n = 27), without tumors (n = 7) and its extracted grafts (n = 10) obtained from patients belongs to the north-western areas of Poland. The determined metal concentrations in the renal cortex and medulla may be arranged in the following descending order: Cd > Pb > Hg. The highest concentrations of Cd and Hg were found in the cortex, while the maximum content Pb was observed in the medulla. Significant correlations were found in the concentrations of the same metals between cortex and medulla and between Pb and Hg in the renal medulla. Pb content was higher in the renal medulla of men than in the cortex of the elderly (above 60 years of age). The highest concentrations of Pb and Hg were found in the cortex and medulla, of the kidneys had not neoplastic changes, and lower content of these metals were found in the extracted kidney grafts. In summary, renal grafts accumulate less heavy metals than cancerous kidneys, what could have been caused by immunosuppressors taken by the graft recipients. Moreover, sex, age and smoking are key factors responsible for xenobiotics concentrations.

Effect of quercetin on cadmium chloride-induced impairments in sexual behaviour and steroidogenesis in male Wistar rats

Cadmium chloride (CdCl₂ ) has been reported to cause reproductive toxicity in male rats, mainly through oxidative stress. This study examined its effect on sexual behaviour, as one of the mechanisms of reproductive dysfunction, as well as the possible ameliorative effect of quercetin (QE) on same. Thirty male Wistar rats (10 weeks old), weighing 270-300 g, were used for this study. They were either orally administered 2% DMSO, CdCl₂ (5 mg/kg b.w.), QE (20 mg/kg b.w.) or CdCl₂ +QE, once daily for 4 weeks, before sexual behavioural studies. The 5th group received CdCl₂ for 4 weeks and allowed 4-week recovery period, before sexual behavioural test. Rats were sacrificed after sexual behavioural studies. The blood, testis and penis were collected for biochemical assays. Cadmium increased mount, intromission and ejaculatory latencies, but reduced their frequencies, compared to control. Serum nitric oxide increased, while penile cyclic guanosine monophosphate reduced in the CdCl₂ -exposed rats, compared to control. CdCl₂ increased testicular cholesterol, but reduced 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-HSD activities, and testosterone concentration. QE better attenuated these negative changes compared to withdrawal of CdCl₂ treatment. In conclusion, CdCl₂ suppressed steroidogenesis, penile erection and sexual behaviour, with poor reversal following withdrawal, while QE attenuated these effects.

Xenobiotic transporters and kidney injury

Renal proximal tubules are targets for toxicity due in part to the expression of transporters that mediate the secretion and reabsorption of xenobiotics. Alterations in transporter expression and/or function can enhance the accumulation of toxicants and sensitize the kidneys to injury. This can be observed when xenobiotic uptake by carrier proteins is increased or efflux of toxicants and their metabolites is reduced. Nephrotoxic chemicals include environmental contaminants (halogenated hydrocarbon solvents, the herbicide paraquat, the fungal toxin ochratoxin, and heavy metals) as well as pharmaceuticals (certain beta-lactam antibiotics, antiviral drugs, and chemotherapeutic drugs). This review explores the mechanisms by which transporters mediate the entry and exit of toxicants from renal tubule cells and influence the degree of kidney injury. Delineating how transport proteins regulate the renal accumulation of toxicants is critical for understanding the likelihood of nephrotoxicity resulting from competition for excretion or genetic polymorphisms that affect transporter function.

Determination of Trace Metal Levels in the General Population of Korea

The purpose of this study was to determine the levels of trace metals in the blood of the general Korean population. A total of 258 healthy individuals, according to their regular medical check-ups, (119 males and 139 females, age ranging from 12 to 78 years old) were enrolled from December 2014 to December 2016. Levels of 10 trace elements were determined using inductively coupled plasma mass spectrometry (ICP-MS). The geometric mean (GM) levels for lead, arsenic, cesium, mercury, aluminum, cadmium, copper, manganese, selenium, and zinc were 15.97 μg/L, 7.19 μg/L, 2.39 μg/L, 3.41 μg/L, 10.57 μg/L, 0.78 μg/L, 979.8 μg/L, 11.06 μg/L, 111.37 μg/L, and 872.7 μg/L, respectively. There were significant gender-related differences in the levels of several metals; male individuals had higher Pb, As, Cs, Hg, and Se than females, while females had higher Cd, Cu, and Mn than males. We noticed remarkably high blood levels of Hg, As and Al in the Korean population. The element concentrations reported represent a new contribution to the knowledge of the blood chemistry for the Korea population. The data can be used to assess the clinical health of this population.

Recombinant heat shock protein 27 (HSP27/HSPB1) protects against cadmium-induced oxidative stress and toxicity in human cervical cancer cells

Cadmium (Cd) is a carcinogen with several well-described toxicological effects in humans, but its molecular mechanisms are still not fully understood. Overexpression of heat shock protein 27 (HSP27/HSPB1)-a multifunctional protein chaperone-has been shown to protect cells from oxidative damage and apoptosis triggered by Cd exposure. The aims of this work were to investigate the potential use of extracellular recombinant HSP27 to prevent/counteract Cd-induced cellular toxicity and to evaluate if peroxynitrite was involved in the development of Cd-induced toxicity. Here, we report that the harmful effects of Cd correlated with changes in oxidative stress markers: upregulation of reactive oxygen species, reduction in nitric oxide (NO) bioavailability, increment in lipid peroxidation, peroxynitrite (PN), and protein nitration; intracellular HSP27 was reduced. Treatments with Cd (100 μM) for 24 h or with the peroxynitrite donor, SIN-1, decreased HSP27 levels (~50%), suggesting that PN formation is responsible for the reduction of HSP27. Pre-treatments of the cells either with Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) (a pharmacological inhibitor of NO synthase) or with recombinant HSP27 (rHSP27) attenuated the disruption of the cellular metabolism induced by Cd, increasing in a 55 and 52%, respectively, the cell viability measured by CCK-8. Cd induced necrotic cell death pathways, although apoptosis was also activated; pre-treatment with L-NAME or rHSP27 mitigated cell death. Our findings show for the first time a direct relationship between Cd-induced toxicity and PN production and a role for rHSP27 as a potential therapeutic agent that may counteract Cd toxicity.

Maternal blood cadmium, lead and arsenic levels, nutrient combinations, and offspring birthweight

Background

Cadmium (Cd), lead (Pb) and arsenic (As) are common environmental contaminants that have been associated with lower birthweight. Although some essential metals may mitigate exposure, data are inconsistent. This study sought to evaluate the relationship between toxic metals, nutrient combinations and birthweight among 275 mother-child pairs.

Methods

Non-essential metals, Cd, Pb, As, and essential metals, iron (Fe), zinc (Zn), selenium (Se), copper (Cu), calcium (Ca), magnesium (Mg), and manganese (Mn) were measured in maternal whole blood obtained during the first trimester using inductively coupled plasma mass spectrometry. Folate concentrations were measured by microbial assay. Birthweight was obtained from medical records. We used quantile regression to evaluate the association between toxic metals and nutrients due to their underlying wedge-shaped relationship. Ordinary linear regression was used to evaluate associations between birth weight and toxic metals.

Results

After multivariate adjustment, the negative association between Pb or Cd and a combination of Fe, Se, Ca and folate was robust, persistent and dose-dependent (p < 0.05). However, a combination of Zn, Cu, Mn and Mg was positively associated with Pb and Cd levels. While prenatal blood Cd and Pb were also associated with lower birthweight. Fe, Se, Ca and folate did not modify these associations.

Conclusion

Small sample size and cross-sectional design notwithstanding, the robust and persistent negative associations between some, but not all, nutrient combinations with these ubiquitous environmental contaminants suggest that only some recommended nutrient combinations may mitigate toxic metal exposure in chronically exposed populations. Larger longitudinal studies are required to confirm these findings.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-017-4225-8) contains supplementary material, which is available to authorized users.

Blood cadmium concentrations and environmental exposure sources in newcomer South and East Asian women in the Greater Toronto Area, Canada

BACKGROUND

Immigrant women are often identified as being particularly vulnerable to environmental exposures and health effects. The availability of biomonitoring data on newcomers is limited, thus, presenting a challenge to public health practitioners in the identification of priorities for intervention.

OBJECTIVES

In fulfillment of data needs, the purpose of this study was to characterize blood concentrations of cadmium (Cd) among newcomer women of reproductive age (19-45 years of age) living in the Greater Toronto Area (GTA), Canada and to assess potential sources of environmental exposures.

METHODS

A community-based model, engaging peer researchers from the communities of interest, was used for recruitment and follow-up purposes. Blood samples were taken from a total of 211 newcomer women from South and East Asia, representing primary, regional origins of immigrants to the GTA, and environmental exposure sources were assessed via telephone survey. Metal concentrations were measured in blood samples (diluted with 0.5% (v/v) ammonium hydroxide and 0.1% (v/v) octylphenol ethoxylate) using a quadrupole ICP-MS. Survey questions addressed a wide range of environmental exposure sources, including dietary and smoking patterns and use of nutritional supplements, herbal products and cosmetics.

RESULTS

A geometric mean (GM) blood Cd concentration of 0.39µg/L (SD:±2.07µg/L) was determined for study participants (min/max: <0.045µg/L (LOD)/2.36µg/L). Several variables including low educational attainment (Relative Ratio (RR) (adjusted)=1.50; 95% CI 1.17-1.91), milk consumption (RR (adjusted)=0.86; 95% CI 0.76-0.97), and use of zinc supplements (RR (adjusted)=0.76; 95% CI 0.64-0.95) were observed to be significantly associated with blood Cd concentrations in the adjusted regression model. The variable domains socioeconomic status (R²_adj=0.11) and country of origin (R²_adj=0.236) were the strongest predictors of blood Cd.

CONCLUSION

Blood Cd concentrations fell below those generally considered to be of human health concern. However, negative health effects cannot be entirely excluded, especially for those that fall in the upper percentile range of the distribution, given the mounting evidence for negative health outcomes at low environmental exposure concentrations.

Serum Folate, Vitamin B-12, Vitamin A, γ-Tocopherol, α-Tocopherol, and Carotenoids Do Not Modify Associations between Cadmium Exposure and Leukocyte Telomere Length in the General US Adult Population

Background: Leukocyte telomere length (LTL) is a biomarker of the aging process and is associated with the risk of chronic disease. Higher exposure to cadmium may be associated with shorter LTL, and adequate nutrient concentrations may be associated with longer LTL; however, the potential interaction between metals and nutrients on LTL has yet to be examined.Objectives: The objective of this study was to evaluate whether serum concentrations of vitamins and carotenoids were associated with LTL, and whether they modified the association between blood cadmium and LTL in the US NHANES (1999-2002).Methods: We evaluated cross-sectional associations between LTL and serum concentrations of vitamin A, γ-tocopherol, α-tocopherol, folate, and vitamin B-12 (1999-2002; n = 7458) and α-carotene, β-carotene, β-cryptoxanthin, lutein + zeaxanthin, and lycopene (2001-2002; n = 4018) in a nationally representative sample of US adults (≥20 y of age) with the use of multivariable linear regression. We further investigated whether vitamin and carotenoid concentrations modified associations between blood cadmium and LTL with models stratified by serum nutrient concentrations and the inclusion of an interaction term.Results: Blood cadmium was inversely associated with LTL (percentage of LTL difference per 1 μg/L = -3.74; 95% CI: -5.35, -2.10). Serum vitamin A was positively associated (percentage of LTL difference per 1 μg/L = 4.01; 95% CI: 0.26, 7.90) and γ-tocopherol was inversely associated (percentage of LTL difference per 1 μg/dL = -2.49; 95% CI: -4.21, -0.73) with LTL. Serum folate (P-trend = 0.06) and α-tocopherol (P-trend = 0.10) were marginally positively associated with LTL, whereas vitamin B-12 (P-trend = 0.78) was not associated with LTL. Serum carotenoids were generally positively associated with LTL. Serum vitamin and carotenoid concentrations did not modify blood cadmium and LTL associations (P-interaction > 0.10).Conclusions: Results from this cross-sectional study suggest that exposure to cadmium and certain nutrients may be associated with LTL in US adults, but the serum concentrations of the vitamins and carotenoids evaluated did not modify cross-sectional associations between cadmium exposure and LTL.

Urinary cadmium levels predict mortality of patients with acute heart failure

BACKGROUND

Acute heart failure (AHF) is a serious condition that is associated with increased mortality in critically ill patients. Previous studies indicated that environmental exposure to cadmium increases mortality of general populations. However, the relationship of cadmium exposure and mortality is unclear for AHF patients.

MATERIALS AND METHODS

A total of 153 patients with AHF in intensive care units (ICUs) met the inclusion criteria and were followed up for 6 months. Demographic data, AHF etiology, hematological and biochemical data, and hospital mortality were recorded. The scores of two predictive systems (Sequential Organ Failure Assessment [SOFA], Acute Physiology and Chronic Health Evaluation II [APACHE II]) for mortality in critically ill patients were calculated, and urinary cadmium levels were recorded.

RESULTS

At the end of the follow-up period, the mortality rate was 24.8%. The survivors (n=115) had higher urinary cadmium levels on day 1 (D1UCd) of ICU admission than non-survivors (n=38). A multiple linear regression analysis revealed a positive correlation between D1UCd and acute kidney injury, but a negative correlation between D1UCd and the level of serum albumin. A multivariate Cox analysis indicated that D1UCd was an independent predictor of mortality in AHF patients. For each increment of 1 μg of D1UCd, the hazard ratio for ICU mortality was 1.20 (95% confidence interval [CI]: 1.09-1.32, P<0.001). The area under the receiver operating characteristic curve for D1UCd was 0.84 (95% CI: 0.78-0.91), better than the values for the SOFA and APACHE II systems.

CONCLUSION

The D1UCd may serve as a single predictor of hospital mortality for AHF patients in the ICU. Because of the high mortality and smaller sample size, more investigations are required to confirm these observations and elucidate the underlying mechanisms.

Functional components of the bacterial CzcCBA efflux system reduce cadmium uptake and accumulation in transgenic tobacco plants

Cadmium (Cd) is a toxic trace element released into the environment by industrial and agricultural practices, threatening the health of plants and contaminating the food/feed chain. Biotechnology can be used to develop plant varieties with a higher capacity for Cd accumulation (for use in phytoremediation programs) or a lower capacity for Cd accumulation (to reduce Cd levels in food and feed). Here we generated transgenic tobacco plants expressing components of the Pseudomonas putida CzcCBA efflux system. Plants were transformed with combinations of the CzcC, CzcB and CzcA genes, and the impact on Cd mobilization was analysed. Plants expressing PpCzcC showed no differences in Cd accumulation, whereas those expressing PpCzcB or PpCzcA accumulated less Cd in the shoots, but more Cd in the roots. Plants expressing both PpCzcB and PpCzcA accumulated less Cd in the shoots and roots compared to controls, whereas plants expressing all three genes showed a significant reduction in Cd levels only in shoots. These results show that components of the CzcCBA system can be expressed in plants and may be useful for developing plants with a reduced capacity to accumulate Cd in the shoots, potentially reducing the toxicity of food/feed crops cultivated in Cd-contaminated soils.

Geographic distribution of cadmium and its interaction with the microbial community in the Longjiang River: risk evaluation after a shocking pollution accident

A shocking Longjiang River cadmium pollution accident occurred in 2012, the effects of which on microbial communities remain unclear. Alkaline precipitation technology was applied for remediation, but concerns rose about the stability of this technology. To understand the geographic distribution of cadmium and its correlation with microbes, in this study, 39 water samples and 39 sludge samples from this river and 2 soil samples from the nearby farmland were collected for chemical and microbial analyses. The Cd concentrations of all water samples were lower than 0.005 mg/L and reached the quality standards for Chinese surface water. A ranking of sludge samples based on Cd contents showed sewage outfall > dosing sites > farmland, all of which were higher than the quality standard for soil. Alkaline precipitation technology was effective for Cd precipitation. Cd was unstable; it was constantly dissolving and being released from the sludge. The Cd content of each phase was mainly influenced by the total Cd content. Over 40,000 effective sequences were detected in each sample, and a total of 59,833 OTUs and 1,273 genera were found using Illumina MiSeq sequencing. Two phyla and 39 genera were notably positively correlated with the Cd distribution, while the cases of 10 phyla and 6 genera were the opposite.

Cadmium chloride treatment of rats significantly impairs membrane integrity of mesenchymal stem cells via electrolyte imbalance and lipid peroxidation, a possible explanation of Cd related osteoporosis

OBJECTIVES

Bone marrow mesenchymal stem cells (MSCs) play an important role in bone health. Cadmium causes osteoporosis, but the exact mechanisms of its effect on MSCs are not known.

MATERIALS AND METHODS

Rats were treated with cadmium chloride (40 mg/l) in drinking water for six weeks, and then the biochemical and morphological studies on MSCs were carried out as a cellular backup for osteoblasts. Viability and proliferation properties of the cells were evaluated using MTT assay, trypan blue, population doubling number, and colony forming assay. Morphology of the cells and biochemical parameters including activity of metabolic (ALP, AST, and ALT) and antioxidant enzymes (SOD, CAT, and POX) as well as the MDA level (as an indication of lipid peroxidation) were investigated. In addition, intracellular calcium, potassium, and sodium content were estimated. Data was analyzed statistically and P<0.05 was taken as the level of significance.

RESULTS

The results showed a significant reduction in viability and proliferation ability of extracted cells when compared to the controls. In addition, it was revealed that the cadmium treatment of rats caused a significant reduction in nuclear diameter and cytoplasm area. Also, there was significant increase in (ALT) and (AST) activity and intracellular calcium and potassium content but no change was observed with sodium content and ALP activity. The results showed [a] significant reduction in the antioxidant enzyme activity and increases in the MDA level.

CONCLUSION

Based on the present study, reduction of viability and proliferation ability of MSCs might be a causative factor of osteoporosis in industrial areas.

Impact of Environmental Pollutant Cadmium on the Establishment of a Cancer Stem Cell Population in Breast and Hepatic Cancer

Cadmium, a heavy metal pollutant, causes cancer. The existence of cancer stem cells (CSCs) in tumors is widely considered to be the reason for the recurrence and treatment failure of cancer. Increasing evidence has confirmed that under certain conditions non-CSCs could be converted into CSCs. The impact of cadmium on the development of CSC lineage in the bulk tumor cell population is not yet studied. The aim of this study was to evaluate the effect of cadmium on the conversion of non-CSCs to CSCs and the identification of CSCs based on the concurrent monitoring of multiple CSC markers. High-content monitoring of molecular markers was performed using quantum dot (QD) nanoprobes and an acousto-optical tunable filter (AOTF)-based imaging device. Cadmium treatment significantly increased the CSC population in MCF-7 and HepG2 cell lines. The cadmium-induced CSCs were identified by a concurrent analysis of stem-cell markers, namely, CD44, CD24, CD133, and ALDH1. Moreover, increased m-RNA expression of CD44, ALDH1, and CD133 and protein expression of p-Ras, p-Raf-1, p-MEK-1, and p-ERK-1 were observed in the cadmium-treated MCF-7 and HepG2 cells. This study demonstrates that cadmium induces the gene expression of CSC markers in the breast and liver cancer cell lineage and promotes the conversion of non-CSCs to CSCs.

Quercetin exerts preventive, ameliorative and prophylactic effects on cadmium chloride - induced oxidative stress in the uterus and ovaries of female Wistar rats

This study examined the possible protective effect of quercetin(QE) on cadmium chloride (CdCl₂) - induced reproductive toxicity in female rats. Cadmium (Cd) accumulated in the uterus and ovaries of rats, decreased antioxidants [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione (GSH)], and raised the concentrations of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in the uterus and ovaries of rats. Serum concentrations of estradiol, progesterone, follicle stimulating hormone and luteinizing hormone decreased significantly after CdCl₂ administration. Caspase-3 activity significantly increased in the ovaries, with an increase in Bax and a decrease in Bcl-2 protein expressions after CdCl₂ treatment. Histopathology of the ovaries revealed significant decrease in follicle number, while the uterus showed cyst-like endometrial glands. All three models of QE treatment [pre-treatment (QE + CdCl₂), post-treatment (CdCl₂+QE), simultaneous treatment (CdCl₂/QE)] decreased Cd accumulation, MDA, H₂O₂, and increased SOD, CAT and GPx activities in the uterus and ovaries, decreased apoptosis of follicular cells, and increased serum reproductive hormones. However, the QE pre-treated model offered better protection against CdCl₂ relative to the other two models. These results suggest that, QE exerts multi-mechanistic protective effects against cadmium toxicity attributable to its antioxidant and anti-apoptotic actions.

Liver and kidney toxicity induced by Afzal smokeless tobacco product in Oman

Afzal, the common smokeless tobacco product (STP) in Oman, is believed to contain toxins that may impair the function of some organs such as liver and kidney. An aqueous extract from Afzal was added to drinking water to be administrated orally to Wistar albino rats (n=72) young and adult from both genders weighing between 60-80g and 150-240g respectively for 8 weeks. Animals were divided into three groups: control (distilled water instead of Afzal extract), low-dose (3mgnicotine/kgbodyweight/day) and high-dose (6mgnicotine/kgbodyweight/day). The animals were euthanized and their blood, liver and kidney were collected for biochemical and histopathological investigations. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were assayed for the liver function, while blood urea nitrogen (BUN) and creatinine (CRT) were assayed for the kidney function. The results showed a significant increase in the ALT, AST, BUN and CRT levels (P<0.05) in both Afzal-treated groups (low and high doses) compared with the control. Histopathological findings revealed the initial but seem to be serious degenerative alterations of periportal fibrosis in liver and edematous and calcified changes in renal glomerulus among Afzal-treated groups. Additionally, the weight gain of the Afzal-treated groups was lower than the control group. Our findings show that the exposure of Wistar rats to the Afzal extract has the potentials of causing decreased weight gain and dose-dependent functional and structural damage to the biochemical and histological profiles of liver and kidney as well as serious biochemical effects.

Metal exposures from aluminum cookware: An unrecognized public health risk in developing countries

Removing lead from gasoline has resulted in decreases in blood lead levels in most of the world, but blood lead levels remain elevated in low and middle-income countries compared to more developed countries. Several reasons for this difference have been investigated, but few studies have examined the potential contribution from locally-made aluminum cookware. In a previous study of cookware from a single African country, Cameroon, artisanal aluminum cookware that is made from scrap metal released significant quantities of lead. In this study, 42 intact aluminum cookware items from ten developing countries were tested for their potential to release lead and other metals during cooking. Fifteen items released ≥1 microgram of lead per serving (250mL) when tested by boiling with dilute acetic acid for 2h. One pot, from Viet Nam, released 33, 1126 and 1426 micrograms per serving in successive tests. Ten samples released >1 microgram of cadmium per serving, and fifteen items released >1 microgram of arsenic per serving. The mean exposure estimate for aluminum was 125mg per serving, more than six times the World Health Organization's Provisional Tolerable Weekly Intake of 20mg/day for a 70kg adult, and 40 of 42 items tested exceeded this level. We conducted preliminary assessments of three potential methods to reduce metal leaching from this cookware. Coating the cookware reduced aluminum exposure per serving by >98%, and similar reductions were seen for other metals as well. Potential exposure to metals by corrosion during cooking may pose a significant and largely unrecognized public health risk which deserves urgent attention.

Intracellular detection of hazardous Cd2+ through a fluorescence imaging technique by using a nontoxic coumarin based sensor

A new coumarin based turn on fluorescent sensor (R1) was reported for the detection of highly hazardous Cd²⁺ with excellent selectivity and sensitivity without any interference of other metal ions.

Efficacy of indigenous probiotic Lactobacillus strains to reduce cadmium bioaccessibility - An in vitro digestion model

The toxic heavy metal cadmium (Cd) appears as one of the major global threats to human and animal health. Human being and aquatic life are exposed to Cd by breathing, eating, or drinking when industrial effluents released into environment. The study was aimed to identify cadmium-binding Lactobacillus strain to reduce its bioaccessibility in in vitro digestion model. In this context, forty-eight lactobacilli strains isolated and characterized from fermented dairy products and human origin were screened for their Cd biosorption potential using Flame Atomic Absorption Spectroscopy (FAAS). The present study revealed that Cd biosorption potential of 48 lactobacilli strains ranged from 1.0832 ± 0.012 to 3.562 ± 0.03 mg Cd g^-1 of cells from initial 10 mg L^-1 cadmium chloride (CdCl₂) aqueous solution. Lactobacillus plantarum strain HD 48 demonstrated highest biosorption of 3.562 ± 0.03 mg Cd g^-1 of cells. Lactobacilli-Cd complex stability indicated its strong stability as even after three washes with Milli-Q water metal desorption was nonsignificant (p < 0.05) and further studies to delineate the influence of Cd (100 mg L^-1 CdCl₂) on their growth. Moreover, these strains were able to reduce Cd bioaccessibility in the in vitro digestion model in the range of 24.71 to 41.62 %. Transmission electron microscopy (TEM) investigations on Cd bioadsorption also revealed its surface associated bioadsorption phenomenon. These findings depicted that probiotic strain L. plantarum HD 48 was found to be endowed with remarkable Cd biosorption ability as well as reduction in its bioaccessibility. These results suggest that probiotic strain L. plantarum HD 48 has immense potential to sequester Cd from aqueous solution which could be further explored as a potent source to diminish body Cd burden.

Possible antioxidant effect of Lycium barbarum polysaccharides on hepatic cadmium-induced oxidative stress in rats

The aim of this study was to investigate the potential protective effect of Lycium barbarum polysaccharides (LBP) pretreatment against cadmium (Cd)-induced hepatotoxicity in rats. Wistar rats were divided into control group, LBP group (300 mg/kg orally, once a day, for 30 days), Cd group (CdCl₂ 4 mg/kg i.p. once), and LBP + Cd group (LBP 300 mg/kg orally, once a day, for 30 days + CdCl₂ 4 mg/kg i.p. 24 h after the last treatment). Cd liver injury was examined by morphological/histological changes, transaminases, total protein concentration, and oxidative stress evaluated by MDA, 3NT, GSH, SOD, and TEAC activities. Cd intoxication caused gross morphological changes with hyperemia of the parenchyma, increased volume, and disappearance of the anatomical limits of the lobes associated with an increase of ALT, GSH, and TEAC in plasma and a decrease of MDA, GSH, and TEAC in liver, SOD, and total proteins in plasma. LBP pretreatment caused a slight improvement in the histological architecture and in the 3NT amount together with a significant improvement of hematic parameters. On the basis of the obtained results, we can affirm that LBP pretreatment can ameliorate liver conditions, but further studies are needed to better evaluate the protective antioxidant effects of LBP against Cd-induced toxicity.

Effects of Cd-based Quantum Dot Exposure on the Reproduction and Offspring of Kunming Mice over Multiple Generations

The potential health risks associated with heavy-metal containing quantum dots (QDs) are a major concern accompanying their increased application in both research and industry. In this contribution, we investigate the effects of QDs on reproductive outcomes in Kunming mice across three generations. Rather than being exposed to QDs during pregnancy, mice were intravenously injected with phospholipid micelle encapsulated CdSe/CdS/ZnS QDs at a dosage of 0.81 mg Cd/kg two weeks before mating. Four treatment groups were studied: non-injected control, female injected, male injected and both parents injected with QDs. Although QDs accumulated in the major organs of treated mice, we did not detect any pregnancy complications or adverse effects. No significant difference in pregnancy outcomes could be identified between the QD treated groups and the control group. More importantly, through behavior monitoring, blood tests and histological evaluations, two generations of the offspring were observed to be in normal and healthy condition. Our results show that QD exposure with a short buffering period before conception does not cause obvious pregnancy complications or significant toxicity effects in treated mice or their offspring. This indicates that a short buffering period after QD exposure may reduce potential risk of QDs to reproductive health.

A coumarin–chalcone hybrid used as a selective and sensitive colorimetric and turn-on fluorometric sensor for Cd2+ detection

A chalcone-based naked-eye colorimetric chemical sensor, (E)-4-hydroxy-3-(3-(4-methoxyphenyl)acryloyl)-2H-chromen-2-one 1a, was developed for selective and sensitive recognition of Cd²⁺ in mixed aqueous–organic media.

Possible antioxidant effect of Lycium barbarum polysaccharides on hepatic cadmium-induced oxidative stress in rats

The aim of this study was to investigate the potential protective effect of Lycium barbarum polysaccharides (LBP) pretreatment against cadmium (Cd)-induced hepatotoxicity in rats. Wistar rats were divided into control group, LBP group (300 mg/kg orally, once a day, for 30 days), Cd group (CdCl₂ 4 mg/kg i.p. once), and LBP + Cd group (LBP 300 mg/kg orally, once a day, for 30 days + CdCl₂ 4 mg/kg i.p. 24 h after the last treatment). Cd liver injury was examined by morphological/histological changes, transaminases, total protein concentration, and oxidative stress evaluated by MDA, 3NT, GSH, SOD, and TEAC activities. Cd intoxication caused gross morphological changes with hyperemia of the parenchyma, increased volume, and disappearance of the anatomical limits of the lobes associated with an increase of ALT, GSH, and TEAC in plasma and a decrease of MDA, GSH, and TEAC in liver, SOD, and total proteins in plasma. LBP pretreatment caused a slight improvement in the histological architecture and in the 3NT amount together with a significant improvement of hematic parameters. On the basis of the obtained results, we can affirm that LBP pretreatment can ameliorate liver conditions, but further studies are needed to better evaluate the protective antioxidant effects of LBP against Cd-induced toxicity.

Cadmium induces oxidative stress and apoptosis in lung epithelial cells

Cadmium (Cd) is one of the well-known highly toxic environmental and industrial pollutants. Cd first accumulates in the nucleus and later interacts with zinc finger proteins of antiapoptotic genes and inhibit the binding of transcriptional factors and transcription. However, the role of Cd in oxidative stress and apoptosis is less understood. Hence, the present study was undertaken to unveil the mechanism of action. A549 cells were treated with or without Cd and cell viability was measured by MTT assay. Treatment of cells with Cd shows reduced viability in a dose-dependent manner with IC₅₀ of 45 μM concentration. Cd significantly induces the reactive oxygen species (ROS), lipid peroxidation followed by membrane damage with the leakage of lactate dehydrogenase (LDH). Cells with continuous exposure of Cd deplete the antioxidant super oxide dismutase (SOD) and glutathione peroxidase (GSH-Px) enzymes. Further, analysis of the expression of genes involved in apoptosis show that both the extrinsic and intrinsic apoptotic pathways were involved. Death receptor marker tumor necrosis factor-α (TNF-α), executor caspase-8 and pro-apoptotic gene (Bax) were induced, while antiapoptotic gene (Bcl-2) was decreased in Cd-treated cells. Fluorescence-activated cell sorting (FACS) analysis further confirms the induction of apoptosis in Cd-treated A549 cells.

Association of Blood Pressure with Exposure to Lead and Cadmium: Analysis of Data from the 2008-2013 Korean National Health and Nutrition Examination Survey

We examined the association of blood pressure with blood levels of cadmium, lead, and their combination in a representative sample of adults from South Korea (Korean National Health and Nutrition Examination Survey, 2008-2013). This cross-sectional study enrolled subjects who were at least 19 years-old, completed a health examination survey, and had blood measurements of lead and cadmium. We estimated the adjusted mean differences in diastolic and systolic blood pressure associated with doubling of blood lead and cadmium by regression of blood pressure against log₂-transformed blood metals and their tertiles after covariate adjustment. Adjusted odds ratios for hypertension and prehypertension were calculated for log₂-transformed blood levels of lead and cadmium and their tertiles. In the general population of Korea, blood lead level was associated with increased BP and risk of hypertension. Blood cadmium levels had a stronger association with elevated blood pressure and risk of hypertension than blood lead levels, and these associations remained significant after statistical adjustment for blood lead. The combination of blood lead and cadmium was more strongly associated with elevated blood pressure than exposure to each individual metal. In females, there was a stronger relationship between blood pressure and blood levels of these metals by analyzing interaction model. After adjustment for confounding factors, there were significant associations of blood pressure with the level of blood lead, cadmium, and their combination in adults from South Korea.

Cadmium and lead exposure and risk of cataract surgery in U.S. adults

Cataract is a major cause of visual dysfunction and the leading cause of blindness. Elevated levels of cadmium and lead have been found in the lenses of cataract patients, suggesting these metals may play a role in cataract risk. This study aimed to examine the associations of blood lead, blood cadmium and urinary cadmium with cataract risk. We identified 9763 individuals aged 50 years and older with blood lead and cadmium levels, and a randomly selected subgroup of 3175 individuals with available urinary cadmium levels, from the National Health and Nutrition Examination Surveys (NHANES) from 1999 to 2008 (mean age=63years). Participants were considered to have cataract if they self-reported prior cataract surgery in NHANES's vision examination. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed using survey logistic regression models. We identified 1737 cataract surgery cases (the weighted prevalence=14.1%). With adjustment for age, race/ethnicity, gender, education, diabetes mellitus, body mass index, cigarette smoking (serum cotinine and pack-years) and urine hydration, every 2-fold increase in urinary cadmium was associated with a 23% higher risk of cataract surgery (OR=1.23, 95% CI: 1.04, 1.46, p=0.021). We found no associations of cataract surgery with blood cadmium (OR=0.97, 95% CI: 0.89, 1.07) and blood lead (OR=0.97, 95% CI: 0.88, 1.06). Mediation analysis showed that for the smoking-cadmium-cataract pathway, the ratio of smoking's indirect effect to the total effect through cadmium was more than 50%. These results suggest that cumulative cadmium exposure may be an important under-recognized risk factor for cataract. However, these findings should be interpreted with a caution because of inconsistent results between urinary cadmium and blood cadmium.

Modulation of cytokines and chemokines expression by NAC in cadmium chloride treated human lung cells

Cadmium (Cd), is one of the most hazardous metals found in the environment. Cd exposure through inhalation has been linked to various diseases in lungs. It was shown that Cd induces proinflammatory cytokines through oxidative stress mechanism. In this report, we studied the immunomodulatory effect of a well known antioxidant, N-acetylcysteine (NAC) on cadmium chloride (CdCl2 ) treated human lung A549 cells through human cytokine array 6. The lung cells were treated with 0 or 75 µM CdCl2 alone, 2.5 mM NAC alone, or co-treated with 2.5 mM NAC and 75 µM CdCl2 for 24 h. The viability of cells was measured by crystal violet dye. The array results were validated by human IL-1alpha enzyme- linked immunosorbent assay (ELISA) kit. The viability of the 75 µM CdCl2 alone treated cells was decreased to 44.5%, while the viability of the co-treated cells with 2.5 mM NAC was increased to 84.1% in comparison with untreated cells. In the cell lysate of CdCl2 alone treated cells, 19 and 8 cytokines were up and down-regulated, while in the medium 15 and 3 cytokines were up and downregulated in comparison with the untreated cells. In the co-treated cells, all these cytokines expression was modulated by the NAC treatment. The IL-1α ELISA result showed the same pattern of cytokine expression as the cytokine array. This study clearly showed the modulatory effect of NAC on cytokines and chemokines expression in CdCl2- treated cells and suggests the use of NAC as protective agent against cadmium toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1612-1619, 2016.

Predictors of cadmium and lead concentrations in the blood of residents from the metropolitan area of Athens (Greece)

The Cd and Pb blood contents of healthy adult subjects who are non-occupationally exposed and living in the metropolitan area of Athens (Greece) have not been assessed thus far. Additionally, Greeks rank first among EU27 in terms of smoking habits. To fill the existing gap, we aimed to evaluate the predictors and propose reference values (RVs) of the Cd (CdB) and Pb (PbB) blood concentrations in residents of the metropolitan area of Athens (Greece). Age, sex, smoking, alcohol drinking, educational status and nutritional habits were used as variables, with an emphasis on smoking. CdB and PbB determinations were performed directly by graphite furnace atomic absorption spectrometry (GFAAS) following the appropriate dilution of the samples with Triton-X-100. The RVs of CdB and PbB proposed for the general adult population of the Metropolitan area of Athens, Greece (upper limit of the 95% CI of the 95th percentile of the distribution of values), were 2.3 and 88μgL(-1) (P95: 1.8 and 77μgL(-1); 95% CI (P95): 1.5-2.3 and 70-88μgL(-1)), respectively. Males had a higher median CdB (0.69μgL(-1)) than females (0.55μgL(-1)). Subjects aged <40years had a lower median CdB (0.51μgL(-1)) than the elderly (≥60years; 0.60μgL(-1)). The CdB in smokers (1.2μgL(-1)) was almost threefold higher than in non-smokers (0.46μgL(-1)). The PbB levels were higher in males (31μgL(-1)) than females (20μgL(-1)). Subjects aged <40years had a lower median PbB (17μgL(-1)) than the elderly (≥60years; 32μgL(-1)). A multiple linear regression analysis demonstrated that the predictor variables for the CdB levels were the standardized beta weight, smoking, age, alcohol consumption, and intake of leafy vegetables, whereas for the PbB levels they were sex and age.

Melatonin antagonizes cadmium-induced neurotoxicity by activating the transcription factor EB-dependent autophagy-lysosome machinery in mouse neuroblastoma cells

Cadmium (Cd), a highly ubiquitous heavy metal, induces neurotoxicity. Melatonin, a major secretory product of the pineal gland, protects against Cd-induced neurotoxicity. However, the mechanism that accounts for this protection remains to be elucidated. Herein, we exposed mouse neuroblastoma cells (Neuro-2a cells) to different concentrations of cadmium chloride (CdCl2 ) (12.5, 25, and 50 μ mol L(-1) ) for 24 hours. We showed that Cd inhibits autophagosome-lysosome fusion and impairs lysosomal function, subsequently leading to nerve cell death. In addition, Cd decreases the level of transcription factor EB (TFEB) but induces the nuclear translocation of TFEB, associated with compromised lysosomal function or a compensatory effect after the impairment of the autophagic flux. Moreover, compared to the 50-μ mol L(-1) Cd group, administration of 1 μ mol L(-1) melatonin increased "TFEB-responsive genes" (P<.05) and the levels of lysosomal-associated membrane protein (0.57±0.06 vs 1.00±0.11, P<.05), preserved lysosomal protease activity (0.52±0.01 vs 0.90±0.02, P<.05), maintained the lysosomal pH level (0.50±0.01 vs 0.87±0.05, P<.01), and enhanced autophagosome-lysosome fusion (0.05±0.00 vs 0.21±0.01, P<.01). Notably, melatonin enhanced TFEB expression (0.37±0.04 vs 0.72±0.07, P<.05) and nuclear translocation (2.81±0.08 vs 3.82±0.05, P<.05). Tfeb siRNA blocked the melatonin-mediated elevation in autophagy-lysosome machinery in Cd-induced neurotoxicity (P<.01). Taken together, these results uncover a potent role for TFEB-mediated autophagy in the pathogenesis of Cd-induced neurotoxicity, suggesting that control of the autophagic pathway by melatonin might provide an important clue for exploring potential targets for novel therapeutics of Cd-induced neurotoxicity.

The risk of overestimating the risk-metal leaching to groundwater near contaminated glass waste deposits and exposure via drinking water

This study investigates metal contamination patterns and exposure to Sb, As, Ba, Cd and Pb via intake of drinking water in a region in southeastern Sweden where the production of artistic glass has resulted in a large number of contaminated sites. Despite high total concentrations of metals in soil and groundwater at the glassworks sites properties, all drinking water samples from households with private wells, located at a 30-640m distance from a glassworks site, were below drinking water criteria from the WHO for Sb, As, Ba and Cd. A few drinking water samples showed concentrations of Pb above the WHO guideline, but As was the only element found in concentrations that could result in human exposure near toxicological reference values. An efficient retention of metals in the natural soil close to the source areas, which results in a moderate impact on local drinking water, is implied. Firstly, by the lack of significant difference in metal concentrations when comparing households located upstream and downstream of the main waste deposits, and secondly, by the lack of correlation between the metal concentration in drinking water and distance to the nearest glassworks site. However, elevated Pb and Cd concentrations in drinking water around glassworks sites when compared to regional groundwater indicate that diffuse contamination of the soils found outside the glassworks properties, and not only the glass waste landfills, may have a significant impact on groundwater quality. We further demonstrate that different mobilization patterns apply to different metals. Regarding the need to use reliable data to assess drinking water contamination and human exposure, we finally show that the conservative modelling approaches that are frequently used in routine risk assessments may result in exposure estimates many times higher than those based on measured concentrations in the drinking water that is actually being used for consumption.

Systematic network assessment of the carcinogenic activities of cadmium

Cadmium has been defined as type I carcinogen for humans, but the underlying mechanisms of its carcinogenic activity and its influence on protein-protein interactions in cells are not fully elucidated. The aim of the current study was to evaluate, systematically, the carcinogenic activity of cadmium with systems biology approaches. From a literature search of 209 studies that performed with cellular models, 208 proteins influenced by cadmium exposure were identified. All of these were assessed by Western blotting and were recognized as key nodes in network analyses. The protein-protein functional interaction networks were constructed with NetBox software and visualized with Cytoscape software. These cadmium-rewired genes were used to construct a scale-free, highly connected biological protein interaction network with 850 nodes and 8770 edges. Of the network, nine key modules were identified and 60 key signaling pathways, including the estrogen, RAS, PI3K-Akt, NF-κB, HIF-1α, Jak-STAT, and TGF-β signaling pathways, were significantly enriched. With breast cancer, colorectal and prostate cancer cellular models, we validated the key node genes in the network that had been previously reported or inferred form the network by Western blotting methods, including STAT3, JNK, p38, SMAD2/3, P65, AKT1, and HIF-1α. These results suggested the established network was robust and provided a systematic view of the carcinogenic activities of cadmium in human.

Protective Role of Quercetin in Cadmium-Induced Cholinergic Dysfunctions in Rat Brain by Modulating Mitochondrial Integrity and MAP Kinase Signaling

With the increasing evidences of cadmium-induced cognitive deficits associated with brain cholinergic dysfunctions, the present study aimed to decipher molecular mechanisms involved in the neuroprotective efficacy of quercetin in rats. A decrease in the binding of cholinergic-muscarinic receptors and mRNA expression of cholinergic receptor genes (M1, M2, and M4) was observed in the frontal cortex and hippocampus on exposure of rats to cadmium (5.0 mg/kg body weight, p.o.) for 28 days compared to controls. Cadmium exposure resulted to decrease mRNA and protein expressions of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) and enhance reactive oxygen species (ROS) generation associated with mitochondrial dysfunctions, ultrastructural changes, and learning deficits. Enhanced apoptosis, as evidenced by alterations in key proteins involved in the pro- and anti-apoptotic pathway and mitogen-activated protein (MAP) kinase signaling, was evident on cadmium exposure. Simultaneous treatment with quercetin (25 mg/kg body weight, p.o.) resulted to protect cadmium-induced alterations in cholinergic-muscarinic receptors, mRNA expression of genes (M1, M2, and M4), and expression of ChAT and AChE. The protective effect on brain cholinergic targets was attributed to the antioxidant potential of quercetin, which reduced ROS generation and protected mitochondrial integrity by modulating proteins involved in apoptosis and MAP kinase signaling. The results exhibit that quercetin may modulate molecular targets involved in brain cholinergic signaling and attenuate cadmium neurotoxicity.

Low-dose oral cadmium increases airway reactivity and lung neuronal gene expression in mice

Inhalation of cadmium (Cd) is associated with lung diseases, but less is known concerning pulmonary effects of Cd found in the diet. Cd has a decades-long half-life in humans and significant bioaccumulation occurs with chronic dietary intake. We exposed mice to low-dose CdCl2 (10 mg/L in drinking water) for 20 weeks, which increased lung Cd to a level similar to that of nonoccupationally exposed adult humans. Cd-treated mice had increased airway hyperresponsiveness to methacholine challenge, and gene expression array showed that Cd altered the abundance of 443 mRNA transcripts in mouse lung. In contrast to higher doses, low-dose Cd did not elicit increased metallothionein transcripts in lung. To identify pathways most affected by Cd, gene set enrichment of transcripts was analyzed. Results showed that major inducible targets of low-dose Cd were neuronal receptors represented by enriched olfactory, glutamatergic, cholinergic, and serotonergic gene sets. Olfactory receptors regulate chemosensory function and airway hypersensitivity, and these gene sets were the most enriched. Targeted metabolomics analysis showed that Cd treatment also increased metabolites in pathways of glutamatergic (glutamate), serotonergic (tryptophan), cholinergic (choline), and catecholaminergic (tyrosine) receptors in the lung tissue. Protein abundance measurements showed that the glutamate receptor GRIN2A was increased in mouse lung tissue. Together, these results show that in mice, oral low-dose Cd increased lung Cd to levels comparable to humans, increased airway hyperresponsiveness and disrupted neuronal pathways regulating bronchial tone. Therefore, dietary Cd may promote or worsen airway hyperresponsiveness in multiple lung diseases including asthma.