Cadmium, environmental exposure, and health outcomes

Copper, Iron, Cadmium, and Arsenic, All Generated in the Universe: Elucidating Their Environmental Impact Risk on Human Health Including Clinical Liver Injury

Humans are continuously exposed to various heavy metals including copper, iron, cadmium, and arsenic, which were specifically selected for the current analysis because they are among the most frequently encountered environmental mankind and industrial pollutants potentially causing human health hazards and liver injury. So far, these issues were poorly assessed and remained a matter of debate, also due to inconsistent results. The aim of the actual report is to thoroughly analyze the positive as well as negative effects of these four heavy metals on human health. Copper and iron are correctly viewed as pollutant elements essential for maintaining human health because they are part of important enzymes and metabolic pathways. Healthy individuals are prepared through various genetically based mechanisms to maintain cellular copper and iron homeostasis, thereby circumventing or reducing hazardous liver and organ injury due to excessive amounts of these metals continuously entering the human body. In a few humans with gene aberration, however, liver and organ injury may develop because excessively accumulated copper can lead to Wilson disease and substantial iron deposition to hemochromatosis. At the molecular level, toxicities of some heavy metals are traced back to the Haber Weiss and Fenton reactions involving reactive oxygen species formed in the course of oxidative stress. On the other hand, cellular homeostasis for cadmium and arsenic cannot be provided, causing their life-long excessive deposition in the liver and other organs. Consequently, cadmium and arsenic represent health hazards leading to higher disability-adjusted life years and increased mortality rates due to cancer and non-cancer diseases. For unknown reasons, however, liver injury in humans exposed to cadmium and arsenic is rarely observed. In sum, copper and iron are good for the human health of most individuals except for those with Wilson disease or hemochromatosis at risk of liver injury through radical formation, while cadmium and arsenic lack any beneficial effects but rather are potentially hazardous to human health with a focus on increased disability potential and risk for cancer. Primary efforts should focus on reducing the industrial emission of hazardous heavy metals.

HSF1 protects cells from cadmium toxicity by governing proteome integrity

BACKGROUND

Cadmium toxicity has been associated with disruption of protein homeostasis by interfering with protein folding processes. Heat shock factor 1 (HSF1) coordinates the rapid and extensive cellular response to maintain proteomic balance facing the challenges from many environmental stressors. Thus, we suspect that HSF1 may shield cells from cadmium toxicity by conserving proteome integrity.

RESULTS

Here, we demonstrate that cadmium, a highly poisonous metal, induces aggregation of cytosolic proteins in human cells, which disrupts protein homeostasis and activates HSF1. Cadmium exposure increases HSF1's phosphorylation, nuclear translocation and DNA bindings. Aside from this, HSF1 goes through liquid-liquid phase separation to form small nuclear condensates upon cadmium exposure. A specific regulatory domain of HSF1 is critical for HSF1's phase separation capability. Most importantly, human cells with impaired HSF1 are sensitized to cadmium, however, cells with overexpressed HSF1 are protected from cadmium toxicity. Overexpression of HSF1 in human cells reduces protein aggregates, amyloid fibrils and DNA damages to antagonize cadmium toxicity.

CONCLUSIONS

HSF1 protects cells from cadmium toxicity by governing the integrity of both proteome and genome. Similar mechanisms may enable HSF1 to alleviate cellular toxicity caused by other heavy metals. HSF1's role in cadmium exposure may provide important insights into the toxic effects of heavy metals on human cells and body organs, allowing us to better manage heavy metal poisoning.

A pair of cadmium-exposed zebrafish affect social behavior of the un-exposed majority

To account for global contamination events, we must identify direct and indirect pollutant effects. Although pollutants can have direct effects on individuals, it is unknown how a few contaminated individuals affect groups, a widespread social organization. We show environmentally relevant levels of cadmium (Cd) can have indirect social effects revealed in the social context of a larger group. Cd-contaminated individuals had poor vision and more aggressive responses, but no other behavioral effects. The presence of experienced Cd-exposed pairs in the groups had an indirect effect on the un-exposed individual's social interactions leading to the shoal becoming bolder and moving closer to a novel object than control groups. Because a few directly affected individuals could indirectly affect social behavior of the un-exposed majority, we believe that such acute but potentially important heavy metal toxicity could inform reliable predictions about the consequences of their use in a changing world.

Chain modeling for the biogeochemical nexus of cadmium in soil-rice-human health system

This paper presents a novel chain model named soil-food-human (SFH) for clarifying the biogeochemical cascades among the triple challenges of cadmium contamination, food safety, and related public health effect. The model was developed based on the integration of spatial distribution pattern of soil environment and the biogeochemical process of cadmium in soil-rice-human health, and it was validated through a case study. In soil environment terms, SFH predicted the spatial distribution of soil properties with an average prediction accuracy of 82.28%. In food production terms, the SFH can identify the safe production zones for planting rice and unsafe area for adjusting croppingsystems with a relative error of 39.41%. In food consumption terms, SFH mapped the high-resolution map of cadmium exposure dose, which gives a new solution to assess the food safety risks for self-sufficient populations. For the health effect of rice cadmium exposure, SFH simulated the spatiotemporal pattern of urinary cadmium based on toxicokinetic which revealed the health effect of rice cadmium exposure. The chain model provides a new insight in understanding the biogeochemical cascades between food production, food safety, and public health, making it possible to develop a comprehensive strategy to tackle cadmium pollution in soil-rice-human health system.

The burden of coronary heart disease and stroke attributable to dietary cadmium exposure in Chinese adults, 2017

Cadmium (Cd) is a metal with a long biological half-life that could cause health issues, such as coronary heart disease (CHD), stroke, and other cardiovascular diseases (CVD). Recent studies showed an ascending trend in the dietary Cd intake in the Chinese population. The contribution of dietary Cd intake to CHD and stroke burden, on the other hand, remains to be established. To calculate the disease burden for CHD and stroke attributable to dietary Cd, we estimated dietary Cd intake by associating the Cd concentration in food with consumption frequency. The toxicokinetic (TK) model and dietary Cd consumption were used to simulate urinary cadmium (U-Cd) concentrations. The population attributable fraction (PAF) can be derived for the computation of the attributable disease burden expressed as Disability-Adjusted Life Years (DALYs) in provinces, genders, and age groups by combining the relative risk (RR) with the population distribution of U-Cd. The mean of dietary Cd consumption and the geometric mean of U-Cd in the Chinese adult population are 0.684 μg/kg bw/day and 0.88 μg/g creatinine. The CHD burden attributable to dietary Cd was 3.26 million DALYs, with a 9.69% proportion of the total CHD burden. The DALYs for stroke attributable to Cd in food was approximately 3.64 million, accounting for 8.22% of the overall stroke burden. Furthermore, the attributable disease burden of CHD and stroke are higher in the south, women, and middle-aged and older adults. Our study suggested that foodborne Cd exposure contributes a considerable proportion of the CHD and stroke burden. More attention is needed to control Cd in food in order to reduce the burden of CHD and stroke in the Chinese population.

An exploratory identification of biological markers of chronic musculoskeletal pain in the low back, neck, and shoulders

Objectives

This study was an in-depth exploration of unique data from a nationally representative sample of adults living in the United States to identify biomarkers associated with musculoskeletal pain.

Methods

We performed secondary analyses of 2003–2004 NHANES data. After a first screening of 187 markers, analyses of 31 biomarkers were conducted on participants aged ≥20 years identified in all counties using the 2000 Census Bureau data (n = 4,742). To assess the association of each biomarker with each pain outcome (acute, subacute and chronic low back, neck, and shoulder pain), analyses were carried out using multivariable logistic regression with adjustments for sex, age and body mass index. Biomarkers were considered as continuous variables and categorized at the median of their distributions.

Results

Pain at any site for ≥24 hours during the past month was reported by 1,214 participants. Of these, 779 mentioned that the pain had lasted for ≥3 months (“chronic pain”). α-carotene, ascorbic acid, β-carotene, mercury and total protein had a statistically significant, inverse association with ≥2 chronic pain sites. Acrylamide, alkaline phosphatase, cadmium, cotinine, glycidamide, homocysteine, retinol, triglycerides and white blood cell count were positively associated with ≥2 chronic pain sites. Few biological markers were associated with acute and subacute pain.

Conclusions

This study identified some biomarkers that were strongly and consistently associated with musculoskeletal pain. These results raise new hypotheses and could have tremendous implications for advancing knowledge in the field. Research on musculoskeletal pain needs to put more effort on the biological dimension of the biopsychosocial model of pain.

Heavy Metal Accumulation, Tissue Injury, Oxidative Stress, and Inflammation in Dromedary Camels Living near Petroleum Industry Sites in Saudi Arabia

The petroleum industry can impact the environment and human health. Heavy metals (HMs), including lead (Pb), cadmium (Cd), nickel (Ni), and vanadium (V), are toxic pollutants found in petroleum that can cause several severe diseases. This study investigated the impact of the oil industry on the Arabian camel (Camelus dromedarius) in the eastern region of Saudi Arabia, pointing to HMs accumulation, tissue injury, redox imbalance, inflammation, and apoptosis. Soil and camel samples (milk, blood, muscle, liver, and kidney) were collected from a site near an oil industry field and another two sites to analyze HMs. Pb, Cd, Ni, and V were increased in the soil and in the camel’s milk, blood, muscle, liver, and kidney at the polluted site. Serum aminotransferases, urea, and creatinine were elevated, and histopathological alterations were observed in the liver and kidney of camels at the oil industry site. Hepatic and renal lipid peroxidation, pro-inflammatory cytokines, Bax, and caspase-3 were increased, whereas cellular antioxidants and Bcl-2 declined in camels at the oil extraction site. In conclusion, the oil industry caused soil and tissue accumulation of HMs, liver and kidney injury, oxidative stress, and apoptosis in camels living close to the oil extraction site. These findings pinpoint the negative impact of the oil industry on the environment, animal, and human health.

Low Level of Serum Cadmium in Relation to Blood Pressures Among Japanese General Population

Hypertension (HT) is an important risk factor for mortality and morbidity. Previous studies showed that cadmium (Cd) was associated with increased blood pressures and the prevalence of HT. This study hypothesized that Cd, regardless of its level, may increase blood pressures/HT. The objective of this study was to examine the associations between a low level of serum Cd concentration and blood pressures/HT among a general population in the Iwaki area, Japan. This was a cross-sectional study, conducted in the Aomori prefecture with 1144 volunteers aged over 19 years old, who were participants of the Iwaki health check-up in 2014. The study assessed questionnaire survey, body composition, and serum Cd concentrations. Median serum Cd concentration was 0.06 ng/mL (interquartile range 0.05-0.08 ng/mL) among our study population. Compared to the lowest quintile of serum Cd concentration group, the highest quintile of serum Cd concentration group had 4.9 mmHg higher systolic blood pressure (SBP) (95% confidence interval [CI] 1.53-8.31, p < 0.01) and 2.4 mmHg higher diastolic blood pressure (DBP) (95% CI 0.36-4.34, p < 0.05), compared to the lowest quintile group. Similarly, the highest quintile of serum Cd concentration group had 1.7 times higher prevalence of HT (95% CI 1.10-2.51, p < 0.05) than the lowest quintile group. This study identified that higher serum Cd concentration was significantly, positively, associated with SBP and DBP and HT prevalence. This study provided evidence for the associations between environmental exposure to Cd and blood pressures/HT which should be considered for future preventive measures.

Metabolomics reveals the mechanism of Antarctic yeast Rhodotorula mucliaginosa AN5 to cope with cadmium stress

Heavy metal pollution in Antarctica has far exceeded expectations. Antarctic yeast is widely present in polar marine environment. The mechanisms of metabolomics effect of heavy metal on polar yeast have not been reported previously. In this study, gas chromatography-mass spectrometry (GC-MS) wascarried out to performed the metabolite profiling analysis of Antarctic sea-ice yeast Rhodotorula mucilaginosa AN5 exposed to different cadmium (Cd) stresses of 5 mM (HM5), 10 mM (HM10) and 20 mM (HM20), respectively. Metabolic profile analysis showed that the composition and contents of cellular metabolites have been altered by cadmium. 93 different metabolites were identified altogether, among which 23, 58 and 81 different metabolites were found in HM5, HM10 and HM20 group respectively. MetaboAnalyst analysis showed that in HM5, HM10 and HM20 groups, 12, 24 and 31 metabolic pathways were involved in the stress of cadmium to R. mucilaginosa, respectively. By contrasting with Kyoto Encyclopedia of Genes and Genomes database, we discovered that exposure of yeast AN5 to Cd stress resulted in profound biochemical changes including amino acids, organic acids and saccharides. These results will supply a nonnegligible basis of studying the adaptive resistance mechanism of Antarctic yeast Rhodotorula mucilaginosa to heavy metal.

Immunomodulation by heavy metals as a contributing factor to inflammatory diseases and autoimmune reactions: Cadmium as an example

Cadmium (Cd) represents a unique hazard because of the long biological half-life in humans (20-30 years). This metal accumulates in organs causing a continuum of responses, with organ disease/failure as extreme outcome. Some of the cellular and molecular alterations in target tissues can be related to immune-modulating potential of Cd. This metal may cause adverse responses in which components of the immune system function as both mediators and effectors of Cd tissue toxicity, which, in combination with Cd-induced alterations in homeostatic reparative activities may contribute to tissue dysfunction. In this work, current knowledge concerning inflammatory/autoimmune disease manifestations found to be related with cadmium exposure are summarized. Along with epidemiological evidence, animal and in vitro data are presented, with focus on cellular and molecular immune mechanisms potentially relevant for the disease susceptibility, disease promotion, or facilitating development of pre-existing pathologies.

Association Between Serum Cadmium and Arsenic Levels with Bladder Cancer: A Case-control Study

Background: Bladder cancer is the second most common cancer of the genitourinary system and the eighth cause of cancer death. In addition to known risk factors such as smoking and urinary stones, trace elements are also effective in causing bladder cancer and other cancers. Objectives: This study was conducted to determine the association between bladder cancer and the carcinogens cadmium and arsenic. Methods: This case-control study was conducted on 40 patients with bladder cancer admitted to Shahid Bahonar Hospital and a control group of 40 healthy individuals in Kerman, Iran, in 2018. The serum levels of arsenic and cadmium were measured by atomic absorptiometry. The paired t-test and chi-square tests were employed to assess the difference between cases and controls groups. An unadjusted and 2 multivariable conditional regression models were separately adjusted on sex, family cancer history, residence, occupation, and smoking and were used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) to assess the association between arsenic and cadmium levels and bladder cancer. The statistical software SPSS version 26 and R software version 3.6.3 were used to perform the statistical analyses. Results: The mean cadmium level was 2.99 ± 1.45 and 2.59 ± 0.46 in the case and control groups, respectively, with no statistically significant difference between the groups (P = 0.100). The mean arsenic level was 2.12 ± 1.04 and 1.43 ± 0.73 in the case and control groups, respectively, demonstrating a statistically significant difference between the groups (P = 0.001). Unadjusted and adjusted conditional logistic regression models indicated significant association between arsenic levels and bladder cancer (unadjusted: odds ratio (OR) (95% CI): 0.66 (0.46 - 0.94), P-value = 0.022; adjusted: OR (95% CI): 0.64 (0.44 - 0.92), P-value = 0.018). Conclusions: Overall, cadmium and arsenic levels are higher in patients with bladder cancer, with a statistically significant difference for arsenic. However, these elements are not interrelated and are not related to other factors.

Cadmium disrupts mitochondrial distribution and activates excessive mitochondrial fission by elevating cytosolic calcium independent of MCU-mediated mitochondrial calcium uptake in its neurotoxicity

Cadmium (Cd) is a ubiquitous environmental and occupational pollutant that is considered as a high-risk factor for neurodegenerative diseases. However, the mechanism underlying Cd-induced neurotoxicity has not been fully elucidated. Abnormal mitochondrial distribution and excessive mitochondrial fission are increasingly implicated in various neurological pathologies. Herein, by exposing primary cortical neurons to Cd (10 and 100 μM) for various times (0, 6, 12, and 24 h), we observed that the rapid motility of the mitochondria in neurons progressively slowed. Many more mitochondria were transported and distributed to the somas of Cd-treated neurons. Coupled with abnormal mitochondrial distribution, Cd exposure triggered excessive mitochondrial fragmentation, followed by mitochondrial membrane potential loss and neuronal damage. However, BAPTA-AM, a chelator of cytosolic calcium ([Ca²⁺]_c), significantly attenuated Cd-induced abnormal mitochondrial distribution and excessive mitochondrial fission, which protected against Cd-induced mitochondrial damage and neuronal toxicity. In contrast to the increase in [Ca²⁺]_c, Cd exposure had no effect on the level of mitochondrial calcium ([Ca²⁺]_m). Inhibiting [Ca²⁺]_m uptake, either by ruthenium 360 (Ru360) or by knock-out of mitochondrial calcium uniporter (MCU), failed to alleviate Cd-induced mitochondrial damage and neuronal toxicity. Additionally, in MCU knock-out neurons, BAPTA-AM effectively prevented Cd-induced abnormal mitochondrial distribution and excessive mitochondrial fission. Taken together, Cd exposure disrupts mitochondrial distribution and activates excessive mitochondrial fission by elevating [Ca²⁺]_c independent of MCU-mediated mitochondrial calcium uptake, thereby leading to neurotoxicity. Chelating overloaded [Ca²⁺]_c is a promising strategy to prevent the neurotoxicity of Cd.

Environmental Toxins Are a Major Cause of Bone Loss

The environmental metals cadmium, lead, and mercury, and chemicals such as pesticides, phthalates, and bisphenols, disrupt bone metabolism in many ways. Body levels of these toxins directly correlate, in a dose-dependent manner, with risk of fracture and osteoporosis. This editorial provides a brief summary of key research showing mechanisms of damage, sources, and key strategies to decrease body load.

Cadmium exacerbates dextran sulfate sodium-induced chronic colitis and impairs intestinal barrier

The potential health risk of environmental pollutant, cadmium, has become a public concern due to its widespread existence and long biological half-life. High-dose cadmium can induce various adverse outcomes, however, the chronic biological influences of cadmium at an environmental dosage and its mechanism remain largely unclear. Here, we investigated the effect of long-term exposure of cadmium at the environmental-relevant concentration on intestinal function. A chronic colitis mouse model was established through multiple cycles of dextran sulfate sodium (DSS) challenge and recovery. 200 nM cadmium in drinking water intensified colonic inflammation induced by DSS (histological score, DSS vs. DSS + Cd: 7.4 ± 1.21 vs. 10.67 ± 0.67, P < 0.05), including fecal occult bleeding and fecal consistency loss. Multiple inflammatory cytokines were significantly up-regulated by cadmium both in colon and plasma (P < 0.05). In addition, intestinal integrity was compromised by cadmium. Goblet cells were markedly reduced (ctrl vs. Cd: 48.33 ± 3.07 vs. 37.5 ± 2.14, P < 0.05) and plasma D-lactate (ctrl vs. Cd: 1.88 ± 0.20 vs. 2.80 ± 0.15, P < 0.01) and diamine oxidase (ctrl vs. Cd: 5.00 ± 0.87 vs. 11.21 ± 2.17, P < 0.05) were increased in cadmium-treated mice, indicating an elevated intestinal permeability. In vitro results showed that long-term exposure of cadmium down-regulated the expression and membrane localization of adherent and tight junction proteins in a time-dependent manner. In conclusion, long-term exposure of environmental dose of cadmium aggravated DSS-induced chronic colitis and disrupted intestinal barrier and impaired the adherent and tight junction proteins. These findings provide a better understanding about the health risk of cadmium in the environment.

Cadmium Uptake in Native Cacao Trees in Agricultural Lands of Bagua, Peru

Cadmium (Cd) contamination threatens cocoa farming in the province of Bagua in Amazonas, Peru. This study reports our assessment of Cd concentrations in cocoa farm soils, and in cocoa roots, leaves, testa, and cotyledon, thus evaluating the magnitude of the problem caused by Cd exposure. For our analysis, we sampled agricultural soil, cocoa roots, leaves and pods at 29 farms in the province of Bagua. Concentrations of Cd in each of the samples were measured and correlated with selected variables at each sampling site. Within our collection of samples, Cd levels showed great variability. In soil, Cd concentrations ranged between 1.02 and 3.54 mg kg−1. Concentrations of this metal within cocoa trees measured from roots, leaves, testa, and cotyledon, Cd ranged from 0.49 mg kg−1 to 2.53 mg kg−1. The cocoa trees exhibited variable degrees of allocation Cd from the soil to their tissues and thus considerable variation among themselves. We found that Cd amounts in roots were up to five times more concentrated than Cd levels in the soils and 2.85 times [Cd] the amounts found in cotyledon. Soil pH is a key variable enabling the uptake of this metal. Most importantly, our evaluation determined that measurements from the majority of farms exceeded the maximum permissible limits established by Peruvian and European legislation.

Heavy Metals in Wastewater and Sewage Sludge from Selected Municipal Treatment Plants in Eastern Cape Province, South Africa

This study assessed the distribution of five heavy metals (Cd, Pb, Cu, Zn, and Fe) across the various stages of treatment in three selected sewage treatment facilities and their receiving waterbodies in the Eastern Cape Province, South Africa. Aqueous and solid (sludge) samples were collected monthly from September 2015 to February 2016. Quantitation was achieved by atomic absorption spectrometry after necessary sample preparations. Concentrations of heavy metal cations in the sludge generally varied from <DL (below detection limit) to 1.17 mg kg−1, <DL to 0.14 mg kg−1, 27.588 to 69.789 mg kg−1, and <DL to 0.099 mg kg−1 for Cu, Cd, Fe and Pb; while Zn was below detection all through. Similarly, the levels of Cu, Cd, and Fe in the influents, effluents, upstream and downstream across the three plants ranged from <DL–6.588 mg L−1, <DL–0.636 mg L−1, <DL–0.878 mg L−1 and <DL–0.711 mg L−1, respectively; Zn and Pb were less than DL in all the matrices and study locations. All the contaminants were below hazardous levels in all the sludge and aqueous samples except Cd which was higher in effluents and surface waters across the board. Wastewater Treatment Plant (WWTP)-A exhibited better removal capacity for Fe (86.6%), compared to WWTP-B (34.7%) and WWTP-C (56.9%). However, the removal of Cu and Zn was very poor in all the treatment facilities studied. Carcinogenic and non-carcinogenic risks evaluated were sufficiently low. This suggests that the levels of contamination, even with respect to Cd, was minimal. Nevertheless, efforts should be made to keep the concentrations of these contaminants at levels safe for humans and aquatic organisms. Furthermore, the use of the effluents from these facilities for irrigation should be discouraged to prevent unnecessary build-up of metals in the soil and plants grown with such, as well as subsequent bioaccumulation and biomagnification in the food chain.

Micro-RNAs: Crossroads between the Exposure to Environmental Particulate Pollution and the Obstructive Pulmonary Disease

Environmental pollution has reached a global echo and represents a serious problem for human health. Air pollution encompasses a set of hazardous substances, such as particulate matter and heavy metals (e.g., cadmium, lead, and arsenic), and has a strong impact on the environment by affecting groundwater, soil, and air. An adaptive response to environmental cues is essential for human survival, which is associated with the induction of adaptive phenotypes. The epigenetic mechanisms regulating the expression patterns of several genes are promising candidates to provide mechanistic and prognostic insights into this. Micro-RNAs (miRNAs) fulfil these features given their ability to respond to environmental factors and their critical role in determining phenotypes. These molecules are present in extracellular fluids, and their expression patterns are organ-, tissue-, or cell-specific. Moreover, the experimental settings for their quantitative and qualitative analysis are robust, standardized, and inexpensive. In this review, we provide an update on the role of miRNAs as suitable tools for understanding the mechanisms behind the physiopathological response to toxicants and the prognostic value of their expression pattern associable with specific exposures. We look at the mechanistic evidence associable to the role of miRNAs in the processes leading to environmental-induced pulmonary disease (i.e., chronic obstructive pulmonary disease).

Biochemical and genetic basis of cadmium biosorption by Enterobacter ludwigii LY6, isolated from industrial contaminated soil

In this study, a cadmium-tolerant bacterium, Enterobacter ludwigii LY6, was isolated from cadmium-contaminated soil in Shifang, Sichuan province, China. The cadmium chloride removal rate of the strain LY6 with a treatment of 100 mg/L cadmium chloride reached 56.0%. Scanning electron microscopy showed that exopolysaccharides (EPS) might be the main means of cadmium adsorption by the strain. X-ray powder diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) analyses indicated that cadmium sulfide nanoparticles formed on the surface of bacteria cultured in a medium containing 100 mg/L cadmium chloride. In addition, the expression of several genes increased with the increase of the cadmium concentration in the medium, including the multiple antibiotic resistance proteins marA and marR, and the cold shock protein CspA. GO functions, such as the redox activity, respiratory chain and transport functions, and KEGG pathways involved in "bacterial chemotaxis" and "terpenoid backbone biosynthesis" were found to be closely related to bacterial cadmium tolerance and biosorption. This is the first report that E. ludwigii can reduce sulfate to form cadmium sulfide nanoparticles under high concentration cadmium exposure. The genes related to cadmium tolerance identified in this study lay a foundation for the genetic breeding of cadmium-tolerant strains.

Cocoa-laden cadmium threatens human health and cacao economy: A critical view

In the recent decades, Cd burden in cocoa-based products threatened global food safety, human health and the future of chocolateries. Increased Cd bioavailability is an acute problem in cacao-based horticulture. Poverty, poor maintenance, unjustified traditional farming, and paucity of knowledge on Cd-binding propensity in cacao discourage the application of risk-mitigation measures. Progressive accumulation of Cd, with a half-life of 10-30 years, in the human body even at ultra-trace levels may lead to serious health complications. If Cd accumulates in the food chain through cocoa products, consequences in children, who are the primary consumers of chocolates, include morbidity and mortality that may result in a significant demographic transition by the year 2050. Developing cacao clones with an innate capability of taking up low Cd levels from soils, and site-specific Cd-cacao research might contribute to limiting the trophic transfer of Cd. This review highlights the possible routes for Cd uptake in cacao plants and discusses the measures to rescue the chocolateries from Cd pollution to promote "healthy" cacao farming. The potential human health risks of chocolate-laden Cd and mitigation strategies to minimize Cd burden in the human body are also presented. The challenges and prospects in Cd-cacao research are discussed as well.

Monitoring and mitigation of toxic heavy metals and arsenic accumulation in food crops: A case study of an urban community garden

Urban community gardens have increased in prevalence as a means to generate fresh fruits and vegetables, including in areas lacking access to healthy food options. However, urban soils may have high levels of toxic heavy metals, including lead and cadmium and the metalloid arsenic, which can lead to severe health risks. In this study, fruit and vegetable samples grown at an urban community garden in southeastern San Diego, the Ocean View Growing Grounds, were sampled repeatedly over a four-year time period in order to measure potential contamination of toxic heavy metals and metalloids and to develop solutions for this problem. Metal nutrient, heavy metal, and metalloid concentrations were monitored in the leaf and fruit tissues of fruit trees over the sampling period. Several of the fruit trees showed uptake of lead in the leaf samples, with Black Mission fig measuring 0.843-1.531 mg/kg dry weight and Mexican Lime measuring 1.103-1.522 mg/kg dry weight over the sampling period. Vegetables that were grown directly in the ground at this community garden and surrounding areas showed arsenic, 0.80 + 0.073 mg/kg dry weight for Swiss chard, and lead, 0.84 ± 0.404 mg/kg dry weight for strawberries, in their edible tissues. The subsequent introduction of raised beds with uncontaminated soil is described, which eliminated any detectable heavy metal or metalloid contamination in these crops during the monitoring period. Recommendations for facilitating the monitoring of edible tissues and for reducing risk are discussed, including introduction of raised beds and collaborations with local universities and research groups.

Inhibition of Mitochondrial Fatty Acid Oxidation Contributes to Development of Nonalcoholic Fatty Liver Disease Induced by Environmental Cadmium Exposure

Cadmium (Cd) is one of the most prevalent toxic metal pollutants widely distributed in water and soil environments. Epidemiological studies have shown that exposure to Cd is implicated in the prevalence of nonalcoholic fatty liver disease (NAFLD) in middle-aged human population, but biological evidence is lacking and its toxicological mechanism remains unclear for the disease predisposition from environmental Cd exposure. In this study, we established a chronic Cd-exposure mouse model mimicking the liver Cd deposition in middle-aged human population to determine whether the environmental Cd exposure can induce NAFLD. Results showed that hepatic Cd burden at levels of 0.95 and 6.04 μg/g wet weight resulting from 20-week Cd exposure at different doses induced NAFLD and nonalcoholic steatohepatitis-like phenotypes in mice, respectively. The Cd exposure caused marked hepatic mitochondrial dysfunction and fatty acid oxidation deficiency, along with significant suppression of sirtuin 1 (SIRT1) signaling pathway in the liver. In vitro study confirmed that Cd evidently inhibited the mitochondrial fatty acid oxidation in hepatocytes and that SIRT1 signaling was potentially involved in the process. Our findings suggest that exposure to environmental Cd is a tangible risk factor for NAFLD, and the induced public health risks deserve greater attention.

Allam A, A. El-Serehy H, N. Maodaa S, M. Mahmoud A. Use of Spilopelia senegalensis as a Biomonitor of Heavy Metal Contamination from Mining Activities in Riyadh (Saudi Arabia)

Simple Summary

Bioindicators and biomonitors are living organisms utilized to appraise the health of the environment or natural ecosystem. Mining, which refers to extraction of valuable materials from the earth, represents a source of heavy metals that can impact the environment, biodiversity, and human health. We investigated the value of the laughing dove (Spilopelia senegalensis) as a biomonitor of environmental contamination with heavy metals from mining practices. Our results revealed the accumulation of heavy metals in the liver, kidneys, and lungs of the laughing dove collected from the mining site. The doves exhibited tissue dysfunction and injury, and decreased antioxidants. These results show the value of the laughing dove as a biomonitor of environmental pollution with heavy metals.

Abstract

Environmental pollution with heavy metals (HMs) is of serious ecological and public health concern worldwide. Mining is one of the main sources of HMs and can impact the environment, species diversity, and human health. This study assessed the value of Spilopelia senegalensis as a biomonitor of environmental contamination with metal(loid)s caused by mining activities. S. senegalensis was collected from a gold mining site and a reference site, and metal(loid)s and biochemical parameters were determined. Lead, cadmium, mercury, vanadium, arsenic, copper, zinc, and iron were significantly increased in the liver, kidney, and lung of S. senegalensis from the mining site. Serum transaminases, alkaline phosphatase, creatinine, and urea were significantly elevated in S. senegalensis from the mining site. Lipid peroxidation and nitric oxide were increased, whereas glutathione and antioxidant enzymes were diminished in the liver and kidney of S. senegalensis from the mining site. In addition, multiple histological alterations were observed in the liver, kidney, and lung of S. senegalensis. In conclusion, mining activities provoke the accumulation of metal(loid)s, oxidative stress, and tissue injury in S. senegalensis. Therefore, S. senegalensis is a valuable biomonitor of environmental pollution caused by mining activities and could be utilized in epidemiological avian studies of human health.

Effects of simulated Cd deposition on soil Cd availability, microbial response, and crop Cd uptake in the passivation-remediation process of Cd-contaminated purple soil

Atmospheric deposition of heavy metals such as Cd is a threat to ecosystems and food safety. Our knowledge is still limited about the effectiveness of remediation process for Cd-contaminated agro-soils under atmospheric Cd deposition. In this study, eight soil amendments were used in a Cd-contaminated purple soil to investigate their impacts on soil Cd availability, microbial response, and Cd uptake by mustard and corn plants via simulating the atmospheric Cd deposition under laboratory incubation and greenhouse conditions. Results showed that the simulated atmospheric Cd deposition increased the soil high-risk Cd (HR, exchangeable and carbonate Cd) and decreased soil medium-risk Cd fraction (MR, bound to Fe/Mn oxide and organic Cd), and the largest direct effects on crop Cd uptakes were 0.94 and 0.66 for mustard and corn based on the path-coefficient analysis, respectively. Generally, Cd deposition led to decreasing soil microbial biomass carbon, populations of bacteria, fungi and actinomycetes, and enzyme activities of urease, catalase, sucrase, and acid phosphatase whereas increasing soil microbial biomass nitrogen. Compared with control and lime treatments, an organic-inorganic combined preparation (OCP) appeared to be effective for remediation of the Cd-contaminated purple soil due to its potential to increase the HR-Cd and reduce both MR-Cd and crop Cd uptake, as accompanied by its neutral effects on soil bacterial alpha diversity and community structure. Results also indicated that application of nitrogen fertilizers should be considered for remediation of the Cd-contaminated soils as nitrogen inputs were demonstrated to promote soil health under elevated Cd condition.

Effects of Mining Activities on Gerbillus nanus in Saudi Arabia: A Biochemical and Histological Study

Mining can impact the environment, biodiversity, and human health through direct and indirect practices. This study investigated the effects of gold mining on Gerbillus nanus, in relation to organ dysfunction and redox imbalance. Soil samples, Lycium shawii, and G. nanus were collected from a site near a mining plant, and a control site. Soil and L. shawii samples from the mining site showed significantly higher cadmium (Cd), copper (Cu), mercury (Hg), arsenic (As), zinc (Zn), lead (Pb), and vanadium (V) levels. Hepatic, renal, and pulmonary Cd, Pb, Hg, Zn, Cu, Fe, As, and V concentrations were significantly higher in G. nanus from the mining site. Markers of liver and kidney function were elevated in serum, and several histological manifestations were observed in the liver, kidney, and lung of G. nanus from the mining site. Malondialdehyde and nitric oxide levels increased, and glutathione and antioxidant enzymes decreased in the liver and kidney of G. nanus. In conclusion, mining practices trigger tissue damage and oxidative stress in G. nanus that live close to the mining site. These findings can represent a scientific basis for evaluating the environmental and health impacts of mining on nearby communities.

Is There Any Relevance Between Serum Heavy Metal Concentration and BBB Leakage in Multiple Sclerosis Patients?

Sharp increase in multiple sclerosis (MS) incidence rate has been observed in Iranian people. In addition, it has been suggested that increased S100B level may be useful as an indicative factor of blood-brain barrier disruption. The propose of this study was to measuring blood arsenic, lead, and cadmium concentration and serum S100B concentration in a group of healthy and multiple sclerosis patients in Tehran as the most polluted city in Iran. All subjects were interviewed regarding age, medical history, possible chemical exposure, acute or chronic diseases, smoking, and dietary habits. Blood heavy metal level was measured by an atomic absorption spectrometer (Varian model 220-Z) conjugated with a graphite furnace atomizer (GTA-110). Also, a serum S100B protein concentration was determined using a commercial ELISA kit. It was observed that all male subjects had higher blood metal level in comparison with healthy controls. Also, MS patients had higher arsenic and cadmium blood concentration in comparison with healthy individuals. Regarding the S100B concentration, it was observed that it had a significant relationship with smoking habit (P value = 0.0001). In addition, arsenic had a greater correlation (63%) with increased serum S100B biomarker level among other elements. BBB leakage was higher in multiple sclerosis than in healthy subjects due to increased S100B release. In addition with regard to the heavy metal exposure especially arsenic and cadmium, these are associated with an increased BBB disruption and it is possible to play a crucial role as a developing agent of multiple sclerosis.

Metal(loid)s in Cucurbita pepo in a Uranium Mining Impacted Area in Northwestern New Mexico, USA

More than 500 unreclaimed mines and associated waste sites exist on the Navajo Nation reservation as a result of uranium (U) mining from the 1940s through the 1980s. For this study, the impact of U-mine waste on a common, locally grown crop food was examined. The goal of this site-specific study was to determine metal(loid) concentration levels of arsenic (As), cadmium (Cd), cesium (Cs), molybdenum (Mo), lead (Pb), thorium (Th), U, vanadium (V) and selenium (Se) in Cucurbita pepo Linnaeus (squash), irrigation water, and soil using inductively coupled plasma-mass spectrometry. The concentrations of metal(loid)s were greatest in roots > leaves > edible fruit (p < 0.05), respectively. There were significant differences between metal(loid)s in squash crop plot usage (<5 years versus >30 years) for V (p = 0.001), As (p < 0.001), U (p = 0.002), Cs (p = 0.012), Th (p = 0.040), Mo (p = 0.047), and Cd (p = 0.042). Lead and Cd crop irrigation water concentrations exceeded the United States Environmental Protection Agency (USEPA) Maximum Contaminant Levels for drinking water for those metals. Edible squash concentration levels were 0.116 mg/kg of As, 0.248 mg/kg of Pb, 0.020 mg/kg of Cd, and 0.006 mg/kg of U. Calculated human ingestion of edible squash did not exceed Provisional Tolerable Weekly Intake or Tolerable Upper Limit levels from intake based solely on squash consumption. There does not appear to be a food-ingestion risk from metal(loid)s solely from consumption of squash. Safer access and emphasis on consuming regulated water was highlighted. Food intake recommendations were provided. Continued monitoring, surveillance, and further research are recommended.

Identification and expression analysis of the GDSL esterase/lipase family genes, and the characterization of SaGLIP8 in Sedum alfredii Hance under cadmium stress

Background

The herb Sedum alfredii (S. alfredii) Hance is a hyperaccumulator of heavy metals (cadmium (Cd), zinc (Zn) and lead (Pb)); therefore, it could be a candidate plant for efficient phytoremediation. The GDSL esterase/lipase protein (GELP) family plays important roles in plant defense and growth. Although the GELP family members in a variety of plants have been cloned and analyzed, there are limited studies on the family's responses to heavy metal-stress conditions.

Methods

Multiple sequence alignments and phylogenetic analyses were performed according to the criteria described. A WGCNA was used to construct co-expression regulatory networks. The roots of S. alfredii seedlings were treated with 100 µM CdCl₂ for qRT-PCR to analyze expression levels in different tissues. SaGLIP8 was transformed into the Cd sensitive mutant strain yeast Δycf1 to investigate its role in resistance and accumulation to Cd.

Results

We analyzed GELP family members from genomic data of S. alfredii. A phylogenetic tree divided the 80 identified family members into three clades. The promoters of the 80 genes contained certain elements related to abiotic stress, such as TC-rich repeats (defense and stress responsiveness), heat shock elements (heat stress) and MYB-binding sites (drought-inducibility). In addition, 66 members had tissue-specific expression patterns and significant responses to Cd stress. In total, 13 hub genes were obtained, based on an existing S. alfredii transcriptome database, that control 459 edge genes, which were classified into five classes of functions in a co-expression subnetwork: cell wall and defense function, lipid and esterase, stress and tolerance, transport and transcription factor activity. Among the hub genes, Sa13F.102 (SaGLIP8), with a high expression level in all tissues, could increase Cd tolerance and accumulation in yeast when overexpressed.

Conclusion

Based on genomic data of S. alfredii, we conducted phylogenetic analyses, as well as conserved domain, motif and expression profiling of the GELP family under Cd-stress conditions. SaGLIP8 could increase Cd tolerance and accumulation in yeast. These results indicated the roles of GELPs in plant responses to heavy metal exposure and provides a theoretical basis for further studies of the SaGELP family's functions.

Effects of soil amendments applied on cadmium availability, soil enzyme activity, and plant uptake in contaminated purple soil

Soil Cd pollution resulting from human activities has become a serious food safety concern. This study was to investigate the impacts of eight soil amendments including a humic acid material (XZ), three organic-inorganic combined materials (FY, PX and PLY) and four inorganic materials (FS, LIME, PLL and PL) on soil Cd availability, enzyme activity, and the uptake by vegetables under incubation, greenhouse and field conditions. Results showed that soil exchangeable Cd (EX-Cd) concentrations under four amendments (FY, XZ, PX, FS) significantly decreased by 12.10-13.59% after 20d treatments, and both PX and PLY resulted in reduced soil EX-Cd fraction while increased fractions of Fe-Mn oxides (OX-Cd), organic matter (OM-Cd) and residual (Res-Cd) in the Cd-contaminated purple soil. PX significantly reduced soil EX-Cd and carbonate-bound (CB-Cd) fractions by 4.4% and 11.4%, and decreased vegetable Cd uptake by 38.8% and 49.1% in greenhouse and field experiments, respectively. Moreover, PX elevated the activities of soil catalase, urease and saccharase by 15.7%, 53.6% and 48.2% in pot soil, which were ~4, ~5 and ~14 times higher those in field soil, respectively. This research demonstrated that PX could be an effective soil amendment to reduce the Cd health and ecological riskthe 1s in the Cd-contaminated purple soil.

Evidences for involvement of estrogen receptor induced ERK1/2 activation in ovarian cancer cell proliferation by Cadmium Chloride

Cadmium (Cd) as a human carcinogen and one of the most toxic industrial and environmental pollutant mimics the estrogenic effects in cell proliferation. So, it might have a role in the incidence and etiology of hormone-related cancers such as ovarian cancer as the most lethal gynecologic malignancy. This study aimed to evaluate the estrogenic effect and underlying mechanism of Cd in ovarian cancer cell line proliferation. OVCAR3 and SKOV3 cell lines were treated with different concentrations of CdCl₂ (0- 50 μM). Cell proliferation was analyzed using MTT and BrdU assay. To evaluate the estrogenic effect of Cd, the cells were pre-incubated with estrogen receptor (ER) antagonist ICI 182,780. The expression of ER was determined using western blotting method. Real-time RT-PCR method was used to assess c-fos, c-jun and FOXO3a mRNA level. The results showed that Cd has an estrogenic proliferative effect at nM concentration range and ICI 182,780 significantly reversed the CdCl₂-induced cell proliferation. Cd also increased the expression of ERs. Cd exposure induced activation of p-ERK1/2 in these cells. Cd also intensified c-jun, c-fos, and FOXO3a mRNA expression. Taken together, the current work suggests that Cd induces ovarian cancer cell proliferation in an ER-dependent mechanism induced ERK1/2 activation pathway. Understanding of downstream targets by which Cd deregulates cell proliferation can be noteworthy to define its underlying carcinogenesis mechanism.

Role of Phytoremediation in Reducing Cadmium Toxicity in Soil and Water

Heavy metals are a noxious form of pollutants present in soil and water. A new plant-based solar energy driven technology, phytoremediation, emerges as eco-friendly and cost-effective approach to remove heavy metal from various media with the help of hyperaccumulating plant species. This review paper aims to provide information on phytoremediation and its mechanisms for heavy metal removal especially to focus on Cadmium (Cd) metal and highlights the role of various hyperaccumulating plants for Cd metal remediation in soil and water. It complies various field case studies which play the important role in understanding the Cd removal through various plants. Additionally, it pinpoints several sources and the effects of Cd and other technologies used for Cd remediation. This paper provides the recent development in mechanisms of Cd hyperaccumulation by different plants, in order to motivate further research in this field.

Blood concentrations of lead, cadmium, mercury and their association with biomarkers of DNA oxidative damage in preschool children living in an e-waste recycling area

Reactive oxygen species (ROS)-induced DNA damage occurs in heavy metal exposure, but the simultaneous effect on DNA repair is unknown. We investigated the influence of co-exposure of lead (Pb), cadmium (Cd), and mercury (Hg) on 8-hydroxydeoxyguanosine (8-OHdG) and human repair enzyme 8-oxoguanine DNA glycosylase (hOGG1) mRNA levels in exposed children to evaluate the imbalance of DNA damage and repair. Children within the age range of 3-6 years from a primitive electronic waste (e-waste) recycling town were chosen as participants to represent a heavy metal-exposed population. 8-OHdG in the children's urine was assessed for heavy metal-induced oxidative effects, and the hOGG1 mRNA level in their blood represented the DNA repair ability of the children. Among the children surveyed, 88.14% (104/118) had a blood Pb level >5 μg/dL, 22.03% (26/118) had a blood Cd level >1 μg/dL, and 62.11% (59/95) had a blood Hg level >10 μg/dL. Having an e-waste workshop near the house was a risk factor contributing to high blood Pb (r _s  = 0.273, p < 0.01), while Cd and Hg exposure could have come from other contaminant sources. Preschool children of fathers who had a college or university education had significantly lower 8-OHdG levels (median 242.76 ng/g creatinine, range 154.62-407.79 ng/g creatinine) than did children of fathers who had less education (p = 0.035). However, we did not observe a significant difference in the mRNA expression levels of hOGG1 between the different variables. Compared with children having low lead exposure (quartile 1), the children with high Pb exposure (quartiles 2, 3, and 4) had significantly higher 8-OHdG levels (β _Q2 = 0.362, 95% CI 0.111-0.542; β _Q3 = 0.347, 95% CI 0.103-0.531; β _Q4 = 0.314, 95% CI 0.087-0.557). Associations between blood Hg levels and 8-OHdG were less apparent. Compared with low levels of blood Hg (quartile 1), elevated blood Hg levels (quartile 2) were associated with higher 8-OHdG levels (β _Q2 = 0.236, 95% CI 0.039-0.406). Compared with children having low lead exposure (quartile 1), the children with high Pb exposure (quartiles 2, 3, and 4) had significantly higher 8-OHdG levels.

Mustafa H, Abdulraouf Saleh H, M.O. El-Fark2 M. Zingiber Officinale Alleviates Maternal and Fetal Hepatorenal Toxicity Induced by Prenatal Cadmium

This study was designed to address the protective effects of Zingiber officinale on the toxic outcomes of prenatal Cadmium administration on pregnancy outcome. Pregnant female Sprague-Dawley rats were randomly divided into four groups (eight rats/each), control group received distilled water, 2nd group treated with 8.8 mg of CdCl2/kg b. wt, 3rd group treated with 250 mg of Zingiber officinale/kg b. wt, and 4th group treated with 250 mg of Zingiber officinale/kg b. wt, followed by 8.8 mg of CdCl2/kg b.wt. Daily body weight of pregnant was recorded from GD1-GD20, and then pregnant rats were sacrificed at GD20. Samples of maternal and fetal livers and kidneys were processed for histological examination. Administration of Cd to pregnant rats showed adverse effects on pregnant mothers and their fetuses; reduced maternal weight gain, reduced absolute organ weights, reduced fetal growth parameters and placental weights together with altered histological appearance of the maternal and fetal livers and kidneys. While co-administration of Zingiber officinale showed an improvement of these toxic alterations. Zingiber officinale through its antioxidant activity could be beneficial against toxic outcomes of Cd exposure during pregnancy.

LncRNA MT1DP Aggravates Cadmium-Induced Oxidative Stress by Repressing the Function of Nrf2 and is Dependent on Interaction with miR-365

Although cadmium (Cd)-induced hepatoxicity is well established, pronounced knowledge gaps remain existed regarding the inherent cellular signaling that dictates Cd toxicity. Specifically, the molecular basis for determining the equilibrium between prosurvival and proapoptotic signaling remains poorly understood. Thus, it is recently revealed that long non-coding RNA (lncRNA) MT1DP, a pseudogene in the metallothionein (MT) family, promoted Cd-induced cell death through activating the RhoC-CCN1/2-AKT pathway and modulating MT1H induction. Here, first the dependency of MT1DP induction on MTF1, an important transcriptional factor in driving the mRNA expression of MT1 members is defined. Additionally, a bridge molecule between MT1DP and nuclear factor erythroid 2-related factor 2 (Nrf2) is established: miR-365. Mechanistically, MT1DP induction under Cd stress decreases the nuclear factor erythroid 2-related factor 2 (Nrf2) level to evoke oxidative stress through the elevation of miR-365, which acted to repress the Nrf2 level via direct binding to its 3'UTR. In contrast to the competing endogenous RNA (ceRNA) mechanism, a new mechanism is proposed: MT1DP elevated the miR-365 level though stabilizing its RNA via direct binding. Collectively, the combined data demonstrate a crucial role of MT1DP in reducing the Nrf2-mediated protection of cells, and this is dependent on the interplay with miR-365. Hence, the study further expands the knowledge of inducible endogenous lncRNA in modulating oxidative stress.

The effect of cadmium exposure on diversity of intestinal microbial community of Rana chensinensis tadpoles

Cadmium is a natural and widely distributed toxicant, and can be commonly found in environment. Intestinal microbiota plays a very important role in maintaining its host's health. The effects of cadmium on the intestinal microbiota composition and stability of amphibians are little known. We exposed Rana chensinensis (R. chensinensis) embryos to different concentrations of cadmium (0, 112 and 448 μg Cd L^-1) until they reached Gosner stage 38, and analyzed their microbial communities using 16S rRNA amplicon sequencing. By measures of both alpha and beta diversity, intestinal microbial communities were significantly differentiated in 448 μg Cd L^-1 exposure groups. Cadmium exposure significantly altered the intestinal microflora diversity and composition of R. chensinensis. At the phylum level, it is worth noting that Fusobacteria and Spirochaetae were not detected in 448 μg Cd L^-1 exposure groups. Firmicutes rapidly decreased in 448 μg Cd L^-1 exposure group. At the genus level, Succinispira (Firmicutes), Desulfovibrio (Proteobacteria) and Fusobacterium (Fusobacteria) vanished in 448 μg Cd L^-1 exposure groups. Our results demonstrate that cadmium exposure changed the composition and decreased the community diversity of intestinal microbiota of R. chensinensis tadpoles. Our study may provide a new framework based on intestinal microbiota to evaluate the response of amphibians to environmental chemicals pollution.

Elevated heavy metals levels in cognitively impaired patients from Pakistan

The deficit in the visuospatial skills, thinking, learning and memory is termed as cognitive impairment. Human exposure to heavy metals is a potential risk factor for developing cognitive impairment. This study aimed to investigate the possible association between the concentration of heavy metals and the extent of cognitive impairment. Blood samples were subjected to microwave assisted acid digestion and evaluated for metals levels using atomic absorption spectrophotometry. We measured the levels of Cu, Pb, Al, Zn, Cd and Mn in 183 patients diagnosed with cognitive impairment; mild (n = 72), moderate (n = 86) and severe (n = 25) and compared them to age-matched healthy controls (n = 90). Results showed that all the aforementioned elements were significantly higher in cognitively impaired patients and increasing concentration was strongly correlated with increase in severity of the disease. The correlation study has shown that among the studied metals, Al and Cu are strongly associated with the cognitive impairment. This suggests the need for decrease in metal exposure to humans from environment, food and industries.

The effect of simulated acid rain on the stabilization of cadmium in contaminated agricultural soils treated with stabilizing agents

Stabilization technology is one of widely used remediation technologies for cadmium (Cd)-contaminated agricultural soils, but stabilized Cd in soil may be activated again when external conditions such as acid rain occurred. Therefore, it is necessary to study the effect of acid rain on the performance of different stabilizing agents on Cd-polluted agriculture soils. In this study, Cd-contaminated soils were treated with mono-calcium phosphate (MCP), mono-ammonium phosphate (MAP), and artificial zeolite (AZ) respectively and incubated 3 months. These treatments were followed by two types of simulated acid rain (sulfuric acid rain and mixed acid rain) with three levels of acidity (pH = 3.0, 4.0, and 5.6). The chemical forms of Cd in the soils were determined by Tessier's sequential extraction procedure, and the leaching toxicities of Cd in the soils were assessed by toxicity characteristic leaching procedure (TCLP). The results show that the three stabilizing agents could decrease the mobility of Cd in soil to some degree with or without simulated acid rain (SAR) treatment. The stabilization performances followed the order of AZ < MAP < MCP. Acid rain soaking promoted the activation of Cd in stabilized soil, and both anion composition and pH of acid rain were two important factors that influenced the stabilization effect of Cd.

Effects of long-term cadmium exposure on urinary metabolite profiles in mice

Cadmium (Cd) is a common environmental pollutant with known toxic effects on the kidney. Urinary metabolomics is a promising approach to study mechanism by which Cd-induced nephrotoxicity. The aim of this study was to elucidate the mechanism of Cd toxicity and to develop specific biomarkers by identifying urinary metabolic changes after a long-term of Cd exposure and with the critical concentration of Cd in the kidney. Urine samples were collected from wild-type 129/Sv mice after 67 weeks of 300 ppm Cd exposure and analyzed by ultra performance liquid chromatography connected with quadrupole time of flight mass spectrometer (UPLC-QTOF-MS) based metabolomics approach. A total of 40 most differentiated metabolites (9 down-regulated and 31 up-regulated) between the control and Cd-exposed group were identified. The majority of the regulated metabolites are amino acids (glutamine, L-aspartic acid, phenylalanine, tryptophan, and D-proline) indicating that amino acid metabolism pathways are affected by long-term exposure of Cd. However, there are also some nucleotides (guanosine, guanosine monophosphate, cyclic AMP, uridine), amino acid derivatives (homoserine, N-acetyl-L-aspartate, N-acetylglutamine, acetyl-phenylalanine, carboxymethyllysine), and peptides. Results of pathway analysis showed that the arginine and proline metabolism, purine metabolism, alanine, aspartate and glutamate metabolism, and aminoacyl-tRNA biosynthesis were affected compared to the control. This study demonstrates that metabolomics is useful to elucidate the metabolic responses and biological effects induced by Cd-exposure.

Relation between cadmium exposure and gestational diabetes mellitus

BACKGROUND

Cadmium (Cd) has been associated with type 2 diabetes in general population. However, the role of Cd in the occurrence of Gestational diabetes mellitus (GDM) remains unclear.

OBJECTIVES

Our study was aimed at investigating whether Cd exposure during pregnancy was associated with increased risk of GDM.

METHODS

Cd concentrations were measured in urine samples from 6837 pregnant women in Wuhan, China, from 2012 to 2014. A "modified Poisson" model with a robust error variance was used to examine the association of GDM with continuous natural logarithm (ln) transformed urinary Cd or quartiles of urinary Cd levels.

RESULTS

For about 3-fold increase in Cd concentrations, there were 16% [relative risk (RR) =1.16; 95% confidence interval (CI): 1.03, 1.33] increase in risk of GDM. Compared with women in the lowest quartile of urinary Cd levels, women in the highest quartile had 1.30 higher risk of GDM [95% CI: 1.05, 1.61; p-trend <0.05]. Further analyses indicated overweight/obese women with higher urinary Cd levels had significantly higher risk of GDM, compared with women in the reference category of lowest quartile of Cd and normal pre-pregnancy body mass index [RR =2.71; 95% CI: 1.81, 4.07].

CONCLUSIONS

Our study presented a significantly positive association between urinary Cd levels and risk of GDM, supporting the hypothesis that environmental exposure to Cd may contribute to the development of GDM.

Gut as a target for cadmium toxicity

The primary objective of the present study was to review the impact of Cd exposure on gut microbiota and intestinal physiology, as well as to estimate whether gut may be considered as the target for Cd toxicity. The review is based on literature search in available databases. The existing data demonstrate that the impact of Cd on gut physiology is two-sided. First, Cd exposure induces a significant alteration of bacterial populations and their relative abundance in gut (increased Bacteroidetes-to-Firmicutes ratio), accompanied by increased lipopolysaccharide (LPS) production, reflecting changed metabolic activity of the intestinal microbiome. Second, in intestinal wall Cd exposure induces inflammatory response and cell damage including disruption of tight junctions, ultimately leading to increased gut permeability. Together with increased LPS production, impaired barrier function causes endotoxinemia and systemic inflammation. Hypothetically, Cd-induced increase gut permeability may also result in increased bacterial translocation. On the one hand, bacteriolysis may be associated with aggravation of endotoxemia. At the same time, together with Cd-induced impairment of macrophage inflammatory response, increased bacterial translocation may result in increased susceptibility to infections. Such a supposition is generally in agreement with the finding of higher susceptibility of Cd-exposed mice to infections. The changed microbiome metabolic activity and LPS-induced systemic inflammation may have a significant impact on target organs. The efficiency of probiotics in at least partial prevention of the local (intestinal) and systemic toxic effects of cadmium confirms the role of altered gut physiology in Cd toxicity. Therefore, probiotic treatment may be considered as the one of the strategies for prevention of Cd toxicity in parallel with chelation, antioxidant, and anti-inflammatory therapy.

Environmental cadmium exposure is associated with elevated risk of chronic otitis media in adults

Objectives

Chronic otitis media (COM) is caused by an infection of the middle ear, although it may also be associated with environmental pollutants. Recent reports found that cadmium exposure could be toxic to middle ear cell lines, but the role of cadmium in the development of COM in humans has not been examined to date. We hypothesised that environmental cadmium exposure was associated with an increased risk of COM in the general population.

Methods

We analysed cross-sectional data for 5331 adults of 20 years of age or above, obtained from the Korea National Health and Nutrition Examination Survey 2010–2012. We examined the association between blood cadmium levels and COM diagnosed by an otolaryngologist.

Results

The highest quartile group of cadmium blood concentration was associated with an OR of 3.33 (95% CI 1.78 to 7.53) for COM, after adjusting for potential confounding factors. Doubling blood cadmium concentration resulted in an OR of 1.58 (95% CI 1.19 to 2.08) for COM. These associations were robust on sensitivity analyses after excluding current smokers and former smokers and after excluding subjects with a potential history of occupational exposure to cadmium.

Conclusions

The results of our study suggest that environmental cadmium exposure is associated with increased risk of COM, and further studies are warranted to understand the pathogenetic mechanism by which COM is caused by cadmium exposure.

Involvement of PKA/DARPP-32/PP1α and β- arrestin/Akt/GSK-3β Signaling in Cadmium-Induced DA-D2 Receptor-Mediated Motor Dysfunctions: Protective Role of Quercetin

Given increasing risk of cadmium-induced neurotoxicity, the study was conducted to delineate the molecular mechanisms associated with cadmium-induced motor dysfunctions and identify targets that govern dopaminergic signaling in the brain involving in vivo, in vitro, and in silico approaches. Selective decrease in dopamine (DA)-D2 receptors on cadmium exposure was evident which affected the post-synaptic PKA/DARPP-32/PP1α and β-arrestin/Akt/GSK-3β signaling concurrently in rat corpus striatum and PC12 cells. Pharmacological inhibition of PKA and Akt in vitro demonstrates that both pathways are independently modulated by DA-D2 receptors and associated with cadmium-induced motor deficits. Ultrastructural changes in the corpus striatum demonstrated neuronal degeneration and loss of synapse on cadmium exposure. Further, molecular docking provided interesting evidence that decrease in DA-D2 receptors may be due to direct binding of cadmium at the competitive site of dopamine on DA-D2 receptors. Treatment with quercetin resulted in the alleviation of cadmium-induced behavioral and neurochemical alterations. This is the first report demonstrating that cadmium-induced motor deficits are associated with alteration in postsynaptic dopaminergic signaling due to a decrease in DA-D2 receptors in the corpus striatum. The results further demonstrate that quercetin has the potential to alleviate cadmium-induced dopaminergic dysfunctions.

Sedum alfredii SaNramp6 Metal Transporter Contributes to Cadmium Accumulation in Transgenic Arabidopsis thaliana

The plant natural resistance-associated macrophage protein (Nramp) family plays an important role in tolerance to heavy metal stress. However, few Nramps have been functionally characterized in the heavy metal-accumulating plant Sedum alfredii. Here, Nramp6 was cloned and identified from S. alfredii and its function analyzed in transgenic Arabidopsis thaliana. SaNramp6 cDNA contains an open reading frame of 1, 638 bp encoding 545 amino acids. SaNramp6's expression can be induced by cadmium (Cd) stress, and, after treatment, it peaked at one week and 12 h in the roots and leaves, respectively. SaNramp6 localized to the plasma membrane in protoplasts isolated from A. thaliana, Nicotiana benthamiana lower leaf and onion (Allium cepa) epidermal cells. The heterologous expression of SaNramp6 in the Δycf1 yeast mutant increased the Cd content in yeast cells. SaNramp6 also rescued the low Cd accumulation of the A. thaliana nramp1 mutant. Transgenic A. thaliana expressing SaNramp6 exhibited high Cd accumulation levels, as determined by a statistical analysis of the Cd concentration, translocation factors and net Cd²⁺ fluxes under Cd stress. Thus, SaNramp6 may play a significant role in improving Cd accumulation, and the gene may be useful for the biotechnological development of transgenic plants for phytoremediation.

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.

Neuro- and nephrotoxicity of subchronic cadmium chloride exposure and the potential chemoprotective effects of selenium nanoparticles

Cadmium (Cd) exposure leads to production of reactive oxygen species (ROS), which are associated with Cd-induced neurotoxicity and nephrotoxicity. Selenium nanoparticles (Se-NPs) have high bioavailability and antioxidant activities so it attracted wide spread attention. The present study examined the possible ameliorative effect of Se-NPs with diameters of 3-5 nm and 10-20 nm against cadmium chloride (CdCl₂)-induced neuro- and nephrotoxicity in rats. Rats were treated with Se-NPs (0 or 0.5 mg/kg BW, s.c.) one hour prior to the CdCl₂ (0 or 5 mg/kg BW, p.o.). Pretreatment with Se-NPs significantly decreased CdCl₂-induced elevation of serum kidney and brain damage biomarkers; lipid peroxidation; the percent of DNA fragmentation and nearly normalized the activity of acetylcholinesterase (AchE) and significantly increased the activity and expression of antioxidant biomarkers in the RNA and protein levels. Se-NPs also attenuated CdCl₂-induced upregulation of kidney and brain pro-apoptotic B-cell CLL/lymphoma 2 associated X (Bax) RNA and protein levels with preventing the increased body burden of Cd and the altered Fe and Cu homeostasis. Histopathological analysis confirmed the biochemical and molecular outcomes. Our data stated that Se-NPs appear to be effective in ameliorating the adverse neurological and nephrotoxic effects induced by CdCl₂ partially through the scavenging of free radicals, metal ion chelation, averting apoptosis and altering the cell-protective pathways. The results indicated that Se-NPs could potentially included as an additive to Cd-based industries to control Cd-induced brain and renal injury.