Cadmium exposure and cancer mortality in the Third National Health and Nutrition Examination Survey cohort

Urinary heavy metals and overall survival of advanced high-grade serous ovarian cancer: A nested case-control study in China

BACKGROUND

Environmental pollution has emerged as a significant determinant in ovarian cancer prognosis. However, limited evidence exists regarding the correlations between heavy metals and ovarian cancer prognosis.

OBJECTIVE

To elucidate the relationship between urinary heavy metals and their mixtures with overall survival (OS) of advanced high-grade serous ovarian cancer (HGSOC).

METHODS

Within the Ovarian Cancer Follow-Up Study, we conducted a nested case-control study. A sum of 159 deceased patients and an equal number of alive patients were included, matched by sample date, body mass index, and age at diagnosis. Urinary concentrations of five heavy metals were quantified: arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and lead (Pb). Conditional logistic regression models were employed to calculate odds ratios (ORs) and their 95 % confidence intervals (CIs). To elucidate joint effects, we utilized quantile g-computation and Bayesian kernel machine regression models.

RESULTS

For the multivariable adjusted conditional logistic regression model, significant associations were found between high urinary levels of As (OR=1.99, 95 %CI: 1.05-3.79), Cd (OR=2.56, 95 %CI: 1.29-5.05), Hg (OR=2.24, 95 %CI: 1.09-4.62), and Pb (OR=3.80, 95 %CI: 1.75-8.27) and worse OS of HGSOC, comparing the highest tertile to the lowest. Analysis of joint effects showed that elevated concentrations of heavy metal mixtures were related to poor OS of HGSOC. Pb exhibited the highest contribution to the overall association within the metal mixtures.

CONCLUSIONS

High urinary heavy metal concentrations were linked to worse OS of HGSOC. Future research is necessary to validate our findings.

Cadmium in biological samples and site-specific cancer risk and mortality: A systematic review of original articles and meta-analyses

BACKGROUND

Cadmium (Cd) is classified as a class 1 carcinogen by the IARC, yet uncertainty persists regarding the total burden of cancer (incidence and mortality) caused by exposure to it, due to the still limited evidence with regard to its aetiological role in cancer at several body sites.

OBJECTIVES AND METHODS

We searched PubMed and EMBASE for meta-analyses and original articles published by February 1st, 2024, that focused on the link between cadmium measured in biological samples (blood, urine, finger-/toe-nails, and hair) and site-specific cancer risk and mortality.

RESULTS

We included 9 meta-analyses and 57 original articles (of these, the design was retrospective in 38 and prospective in 19, and Cd levels were quantified in blood, n=33, urine, n=19, both blood and urine, n=2, or finger-/toenail, n=3). Current data consistently suggest a causal role of exposure to cadmium in pancreas, lung, and bladder carcinogenesis. Total cancer risk and mortality are also positively correlated with Cd levels in biological samples. The evidence is weak or inconclusive for the remaining cancer sites (including breast and prostate), mostly due to the limited number of studies available to date and/or methodological limitations.

DISCUSSION

Exposure to cadmium poses a risk for increased cancer incidence and mortality. Cadmium-related cancer burden might indeed be currently underestimated, as the amount of available evidence for most cancer sites and types is currently limited, and more research in the field is warranted. Continuing efforts to contain Cd pollution and mitigate associated health risk are also needed.

Cadmium transport by mammalian ATP-binding cassette transporters

Cellular responses to toxic metals depend on metal accessibility to intracellular targets, reaching interaction sites, and the intracellular metal concentration, which is mainly determined by uptake pathways, binding/sequestration and efflux pathways. ATP-binding cassette (ABC) transporters are ubiquitous in the human body-usually in epithelia-and are responsible for the transfer of indispensable physiological substrates (e.g. lipids and heme), protection against potentially toxic substances, maintenance of fluid composition, and excretion of metabolic waste products. Derailed regulation and gene variants of ABC transporters culminate in a wide array of pathophysiological disease states, such as oncogenic multidrug resistance or cystic fibrosis. Cadmium (Cd) has no known physiological role in mammalians and poses a health risk due to its release into the environment as a result of industrial activities, and eventually passes into the food chain. Epithelial cells, especially within the liver, lungs, gastrointestinal tract and kidneys, are particularly susceptible to the multifaceted effects of Cd because of the plethora of uptake pathways available. Pertinent to their broad substrate spectra, ABC transporters represent a major cellular efflux pathway for Cd and Cd complexes. In this review, we summarize current knowledge concerning transport of Cd and its complexes (mainly Cd bound to glutathione) by the ABC transporters ABCB1 (P-glycoprotein, MDR1), ABCB6, ABCC1 (multidrug resistance related protein 1, MRP1), ABCC7 (cystic fibrosis transmembrane regulator, CFTR), and ABCG2 (breast cancer related protein, BCRP). Potential detoxification strategies underlying ABC transporter-mediated efflux of Cd and Cd complexes are discussed.

The dynamic face of cadmium-induced Carcinogenesis: Mechanisms, emerging trends, and future directions

Cadmium (Cd) is a malleable element with odorless, tasteless characteristics that occurs naturally in the earth's crust, underground water, and soil. The most common reasons for the anthropological release of Cd to the environment include industrial metal mining, smelting, battery manufacturing, fertilizer production, and cigarette smoking. Cadmium-containing products may enter the environment as soluble salts, vapor, or particle forms that accumulate in food, soil, water, and air. Several epidemiological studies have highlighted the association between Cd exposure and adverse health outcomes, especially renal toxicity, and the impact of Cd exposure on the development and progression of carcinogenesis. Also highlighted is the evidence for early-life and even maternal exposure to Cd leading to devastating health outcomes, especially the risk of cancer development in adulthood. Several mechanisms have been proposed to explain how Cd mediates carcinogenic transformation, including epigenetic alteration, DNA methylation, histone posttranslational modification, dysregulated non-coding RNA, DNA damage in the form of DNA mutation, strand breaks, and chromosomal abnormalities with double-strand break representing the most common DNA form of damage. Cd induces an indirect genotoxic effect by reducing p53's DNA binding activity, eventually impairing DNA repair, inducing downregulation in the expression of DNA repair genes, which might result in carcinogenic transformation, enhancing lipid peroxidation or evasion of antioxidant interference such as catalase, superoxide dismutase, and glutathione. Moreover, Cd mediates apoptosis evasion, autophagy activation, and survival mechanisms. In this review, we decipher the role of Cd mediating carcinogenic transformation in different models and highlight the interaction between various mechanisms. We also discuss diagnostic markers, therapeutic interventions, and future perspectives.

Role of neighborhood context in ovarian cancer survival disparities: current research and future directions

Ovarian cancer is the fifth leading cause of cancer-associated mortality among US women with survival disparities seen across race, ethnicity, and socioeconomic status, even after accounting for histology, stage, treatment, and other clinical factors. Neighborhood context can play an important role in ovarian cancer survival, and, to the extent to which minority racial and ethnic groups and populations of lower socioeconomic status are more likely to be segregated into neighborhoods with lower quality social, built, and physical environment, these contextual factors may be a critical component of ovarian cancer survival disparities. Understanding factors associated with ovarian cancer outcome disparities will allow clinicians to identify patients at risk for worse outcomes and point to measures, such as social support programs or transportation aid, that can help to ameliorate such disparities. However, research on the impact of neighborhood contextual factors in ovarian cancer survival and in disparities in ovarian cancer survival is limited. This commentary focuses on the following neighborhood contextual domains: structural and institutional context, social context, physical context represented by environmental exposures, built environment, rurality, and healthcare access. The research conducted to date is presented and clinical implications and recommendations for future interventions and studies to address disparities in ovarian cancer outcomes are proposed.

Human placental microRNAs dysregulated by cadmium exposure predict neurobehavioral outcomes at birth

BACKGROUND

Prenatal cadmium (Cd) exposure has been implicated in both placental toxicity and adverse neurobehavioral outcomes. Placental microRNAs (miRNAs) may function to developmentally program adverse pregnancy and newborn health outcomes in response to gestational Cd exposure.

METHODS

In a subset of the Rhode Island Child Health Study (RICHS, n = 115) and the New Hampshire Birth Cohort Study (NHBCS, = 281), we used small RNA sequencing and trace metal analysis to identify Cd-associated expression of placental miRNAs using negative binomial generalized linear models. We predicted mRNAs targeted by Cd-associated miRNAs and relate them to neurobehavioral outcomes at birth through the integration of transcriptomic data and summary scores from the NICU Network Neurobehavioral Scale (NNNS).

RESULTS

Placental Cd concentrations are significantly associated with the expression level of five placental miRNAs in NHBCS, with similar effect sizes in RICHS. These miRNA target genes overrepresented in nervous system development, and their expression is correlated with NNNS metrics suggestive of atypical neurobehavioral outcomes at birth.

CONCLUSIONS

Gestational Cd exposure is associated with the expression of placental miRNAs. Predicted targets of these miRNAs are involved in nervous system development and may also regulate placental physiology, allowing their dysregulation to modify developmental programming of early life health outcomes.

IMPACT

This research aims to address the poor understanding of the molecular mechanisms governing adverse pregnancy and newborn health outcomes in response to Gestational cadmium (Cd) exposure. Our results outline a robust relationship between Cd-associated placental microRNA expression and NICU Network Neurobehavioral Scales (NNNS) at birth indicative of atypical neurobehavior. This study utilized healthy mother-infant cohorts to describe the role of Cd-associated dysregulation of placental microRNAs as a potential mechanism by which adverse neurobehavioral outcomes are developmentally programmed.

Association of Urinary Biomarkers of Smoking-Related Toxicants with Lung Cancer Incidence in Smokers: The Multiethnic Cohort Study

BACKGROUND

While cigarette smoking is the leading cause of lung cancer, the majority of smokers do not develop the disease over their lifetime. The inter-individual differences in risk among smokers may in part be due to variations in exposure to smoking-related toxicants.

METHODS

Using data from a subcohort of 2,309 current smokers at the time of urine collection from the Multiethnic Cohort Study, we prospectively evaluated the association of ten urinary biomarkers of smoking-related toxicants [total nicotine equivalents (TNE), a ratio of total trans-3'-hydroxycotinine (3-HCOT)/cotinine (a phenotypic measure of CYP2A6 enzymatic activity), 4-(methylnitrosamino)-1-3-(pyridyl)-1-butanol (NNAL), S-phenylmercapturic acid (SPMA), 3-hydroxypropyl mercapturic acid (3-HPMA), phenanthrene tetraol (PheT), 3-hydroxyphenanthrene (PheOH), the ratio of PheT/PheOH, cadmium (Cd), and (Z)-7-(1R,2R,3R,5S)-3,5-dihydroxy-2-[(E,3S)-3-hydroxyoct-1-enyl]cyclopenyl]hept-5-enoic acid (8-iso-PGF2α)] with lung cancer risk (n = 140 incident lung cancer cases over an average of 13.4 years of follow-up). Lung cancer risk was estimated using Cox proportional hazards models.

RESULTS

After adjusting for decade of birth, sex, race/ethnicity, body mass index, self-reported pack-years, creatinine, and urinary TNE (a biomarker of internal smoking dose), a one SD increase in log total 3-HCOT/cotinine (HR, 1.33; 95% CI, 1.06-1.66), 3-HPMA (HR, 1.41; 95% CI, 1.07-1.85), and Cd (HR, 1.45; 95% CI, 1.18-1.79) were each associated with increased lung cancer risk.

CONCLUSIONS

Our study demonstrates that urinary total 3-HCOT/cotinine, 3-HPMA, and Cd are positively associated with lung cancer risk. These findings warrant replication and consideration as potential biomarkers for smoking-related lung cancer risk.

IMPACT

These biomarkers may provide additional information on lung cancer risk that is not captured by self-reported smoking history or TNE. See related commentary by Etemadi et al., p. 289.

Estimation of health risks associated with dietary cadmium exposure

In much of the world, currently employed upper limits of tolerable intake and acceptable excretion of cadmium (Cd) (ECd/Ecr) are 0.83 µg/kg body weight/day and 5.24 µg/g creatinine, respectively. These figures were derived from a risk assessment model that interpreted β2-microglobulin (β2MG) excretion > 300 μg/g creatinine as a "critical" endpoint. However, current evidence suggests that Cd accumulation reduces glomerular filtration rate at values of ECd/Ecr much lower than 5.24 µg/g creatinine. Low ECd/Ecr has also been associated with increased risks of kidney disease, type 2 diabetes, osteoporosis, cancer, and other disorders. These associations have cast considerable doubt on conventional guidelines. The goals of this paper are to evaluate whether these guidelines are low enough to minimize associated health risks reliably, and indeed whether permissible intake of a cumulative toxin like Cd is a valid concept. We highlight sources and levels of Cd in the human diet and review absorption, distribution, kidney accumulation, and excretion of the metal. We present evidence for the following propositions: excreted Cd emanates from injured tubular epithelial cells of the kidney; Cd excretion is a manifestation of current tissue injury; reduction of present and future exposure to environmental Cd cannot mitigate injury in progress; and Cd excretion is optimally expressed as a function of creatinine clearance rather than creatinine excretion. We comprehensively review the adverse health effects of Cd and urine and blood Cd levels at which adverse effects have been observed. The cumulative nature of Cd toxicity and the susceptibility of multiple organs to toxicity at low body burdens raise serious doubt that guidelines concerning permissible intake of Cd can be meaningful.

Assessment of indoor air quality and their inter-association in hospitals of northern India-a cross-sectional study

This study was commenced to evaluate the indoor and outdoor air quality concentrations of PM_2.5, sub-micron particles (PM_>2.5, PM_1.0-2.5, PM_{0.50 -1.0}, PM_0.25-0.50, and PM_<0.25), heavy metals, and microbial contaminants along with their identification in three different hospitals of Lucknow City. The study was conducted from February 2022 to April 2022 in hospitals situated in the commercial, residential, and industrial belts of the city. The indoor concentration trend of particulate matter as observed during the study suggested that most of the highest concentrations belonged to the hospital situated in an industrial area. The highest obtained indoor and outdoor concentrations for PM_1.0-2.5, PM_0.50-1.0, PM_0.25-0.50, and PM_<0.25 are 40.44 µg/m³, 56.08 µg/m³, 67.20 µg/m³, 74.50 µg/m³, 61.9 µg/m³, 79.3 µg/m³, 82.0 µg/m³, and 93.9 µg/m³, respectively, which belonged to hospital C situated in the industrial belt. However, for PM_>2.5, the highest indoor concentration obtained belonged to hospital B, i.e., 30.7 µg/m³, which is situated in the residential belt of the city. Regarding PM_2.5, the highest indoor and outdoor concentrations obtained are 149.41 µg/m³ and 227.45 µg/m³, which were recorded at hospital A and hospital C, respectively. The present study also observed that a high bacterial load of 1389.21 CFU/m³ is recorded in hospital B, and the fungi load was highest in hospital C with 786.34 CFU/m³. Henceforth, the present study offers thorough information on the various air pollutants in a crucial indoor setting, which will further aid the researchers in the field to identify and mitigate the same more precisely.

The Role of Lead and Cadmium in Gynecological Malignancies

Lead and cadmium are non-essential and toxic heavy metals. Their presence and elevated levels can lead to many pathologies. They disrupt the antioxidant properties of many enzymes, consume the resources of antioxidant cells, and thus participate in the generation of oxidative stress, which may result in DNA damage. In addition, they have been found to be carcinogenic through their genotoxic properties. They have been shown to be present in various types of cancer, including cancer of the female reproductive system. Both metals have been recognized as metalloestrogens, which are important in hormone-related cancers. Participation in the oncogenesis of ovarian, endometrial and cervical cancer was analysed in detail, using the available research in this field. We emphasize their role as potential biomarkers in cancer risk and diagnosis as well as advancement of gynaecological malignancies.

Association of urinary or blood heavy metals and mortality from all causes, cardiovascular disease, and cancer in the general population: a systematic review and meta-analysis of cohort studies

Amounting epidemiological evidence has shown detrimental effects of heavy metals on a wide range of diseases. However, the effect of heavy metal exposure on mortality in the general population remains unclear. The primary objective of this study was to clarify the associations between heavy metals and mortality from all causes, cardiovascular disease (CVD), and cancer based on prospective studies. We comprehensively searched Pubmed, Embase, and Web of Science electronic databases to identify studies published from their inception until 1 March 2022. Investigators identified inclusion criteria, extracted study characteristics, and assessed the methodological quality of included studies according to standardized guidelines. Meta-analysis was conducted if the effect estimates of the same outcome were reported in at least three studies. Finally, 42 original studies were identified. The results of meta-analysis showed that cadmium and lead exposure was significantly associated with mortality from all causes, CVD, and cancer in the general population. Moderate evidence suggested there was a link between arsenic exposure and mortality. The adverse effects of mercury and other heavy metals on mortality were inconclusive. Epidemiological evidence for the joint effect of heavy metal exposure on mortality was still indeterminate. In summary, our study provided compelling evidence that exposure to cadmium, lead, and arsenic were associated with mortality from all causes, CVD, and cancer, while the evidence on other heavy metals, for example mercury, was insignificant or indeterminate. Nevertheless, further prospective studies are warranted to explore the joint effects of multiple metal exposure on mortality.

Cadmium (Cd) and Lead (Pb) topsoil levels and incidence of childhood leukemias

There are few well-established risk factors for childhood leukemias. While the frequency of childhood leukemias might be partially attributable to some diseases (accounting for a small fraction of cases) or ionizing radiation, the role of heavy metals has not been assessed. The objective of our study was to assess the potential association between levels of cadmium (Cd) and lead (PB) in soil and childhood leukemias incidence. We conducted a population-based case-control study of childhood leukaemia in Spain, covering 2897 incident cases gathered from the Spanish Registry of Childhood Tumours and including 14 Spanish Regions with a total population of 5,307,433 children (period 1996-2015). Cd and Pb bioavailable levels at every children's home address were estimated using data from the Geochemical Atlas of Spain. We used logistic regression to estimate odds ratios (ORs) and their 95% confidence intervals (95%CIs); we included as covariates: sex, rurality, employment rate and socioeconomic status. Metal levels were analysed according to two definitions: as continuous variable assuming linearity and as categorical variables to explore a potentially nonlinear association (quantiles). Increases in both Cd and Pb topsoil levels were associated with increased probability of childhood leukemias incidence. The results for the models with the continuous variables showed that a unit increase on the topsoil level was associated with an OR of 1.11 for Cd (95%CI 1.00-1.24) and an OR of 1.10 for Pb (95%CI 0.99-1.21). Our study may point towards a possible link between residential Cd and Pb topsoil levels and the probability of childhood leukemias incidence. Residing in a location with the highest concentrations of these heavy metals compared to those locations with the lowest could increase the risk around a 20%, for both Cd and Pb.

Air-polluted environmental heavy metal exposure increase lung cancer incidence and mortality: A population-based longitudinal cohort study

BACKGROUND

An increased risk of lung cancer has been observed due to exposure to certain environmental heavy metals. This study elucidated the role of air-polluted heavy metals in the development of lung cancer.

METHODS

A longitudinal cohort study involving the general population was conducted to compare heavy metal content among lung cancer patients. The urine concentrations of heavy metals were measured. Questionnaire surveys were designed to collect exposure-related demographic and lifestyle data of the study subjects.

RESULTS

Participants residing near the petrochemical industrial area with higher air Cd concentration had relatively higher urinary concentration of Cd. After adjusting for sociodemographic and behavioral factors, tobacco smoking and air pollution remained as potential sources of Cd exposure. An increased prevalence of lung cancer was observed in the highly polluted zone. The risk of lung cancer incidence increased 1.25-fold for each 1 μg/g-creatinine increase in urine Cd level. Patients with lung cancer had significantly higher urinary Cd concentrations. Lung cancer patients with higher urinary Cd level had significantly poor survival (urine Cd level ≥ 1.58 vs <1.58 μg/g-creatinine; survival, medium, 192.0 vs 342.5 days, p < 0.001). At the longitudinal follow-up, participants with higher urinary Cd level had a higher risk of lung cancer incidence (urine Cd level ≥ 1.58 vs <1.58 μg/g-creatinine: 3.91% v.s. 0.87%, hazard ratio: 4.65, p < 0.001).

CONCLUSIONS

Accumulation of Cd could be a risk of lung cancer occurrence. High exposure to Cd may result in poor prognosis in lung cancer patients.

The Influence of Interaction between Cadmium with 17β-Estradiol, 2-Methoxyestradiol and 16α-Hydroxyestrone on Viability and p-Glycoprotein in Ovarian Cancer Cell Line

Occupational and environmental exposure to xenoestrogens, a subgroup of endocrine disruptors (EDCs), can affect the endocrine system and increase the risk of cancer, primarily the hormone-dependent kind. This type of cancer includes ovarian cancer, which is the leading cause of death from gynecological tumors. The aim of this study was to assess the role of 17β-estradiol and its metabolites: 2-MeOE2, 16α-OHE1 in exposure to the metalloestrogen cadmium. The effect of interactions of cadmium with estrogens on the viability of cells in malignant ovarian cancer cells SKOV-3 was investigated, both in simultaneous action and in the pre-incubation model. There are no known interactions between estrogens and cadmium in ovarian cancer cells. Due to the frequent occurrence of multidrug resistance (MDR) in ovarian cancer, the effects of estrogens and cadmium on MDR in SKOV-3, measured as P-glycoprotein (P-gp), were assessed. An interaction study showed that E2 had an antagonistic effect on cadmium-induced cell damage, while 2-MeOE2 showed less of a protective effect in combination with CdCl₂ than E2. There were two types of interaction: toxic synergism and beneficial antagonism. E2 and cadmium increased P-gp expression in SKOV-3 cells, while 2-MeOE2 decreased P-gp expression to a potentially beneficial effect on MDR prevention. The obtained results constitute an interesting starting point for further research in the field of interactions between estrogens and xenoestrogens in ovarian cancer.

Role of Autophagy in Cadmium-Induced Hepatotoxicity and Liver Diseases

Cadmium (Cd) is a toxic pollutant that is associated with several severe human diseases. Cd can be easily absorbed in significant quantities from air contamination/industrial pollution, cigarette smoke, food, and water and primarily affects the liver, kidney, and lungs. Toxic effects of Cd include hepatotoxicity, nephrotoxicity, pulmonary toxicity, and the development of various human cancers. Cd is also involved in the development and progression of fatty liver diseases and hepatocellular carcinoma. Cd affects liver function via modulation of cell survival/proliferation, differentiation, and apoptosis. Moreover, Cd dysregulates hepatic autophagy, an endogenous catabolic process that detoxifies damaged cell organelles or dysfunctional cytosolic proteins through vacuole-mediated sequestration and lysosomal degradation. In this article, we review recent developments and findings regarding the role of Cd in the modulation of hepatotoxicity, autophagic function, and liver diseases at the molecular level.

Influence of the Levels of Arsenic, Cadmium, Mercury and Lead on Overall Survival in Lung Cancer

The effects of heavy metals on cancer risk have been widely studied in recent decades, but there is limited data on the effects of these elements on cancer survival. In this research, we examined whether blood concentrations of the heavy metals arsenic, cadmium, mercury and lead were associated with the overall survival of lung cancer patients. The study group consisted of 336 patients with lung cancer who were prospectively observed. Blood concentrations of heavy metals were measured to study the relationship between their levels and overall survival using Cox proportional hazards analysis. The hazard ratio of death from all causes was 0.99 (p = 0.94) for arsenic, 1.37 (p = 0.15) for cadmium, 1.55 (p = 0.04) for mercury, and 1.18 (p = 0.47) for lead in patients from the lowest concentration quartile, compared with those in the highest quartile. Among the patients with stage IA disease, this relationship was statistically significant (HR = 7.36; p < 0.01) for cadmium levels in the highest quartile (>1.97–7.77 µg/L) compared to quartile I (0.23–0.57 µg/L, reference). This study revealed that low blood cadmium levels <1.47 µg/L are probably associated with improved overall survival in treated patients with stage IA disease.

Environmental exposure to cadmium and risk of thyroid cancer from national industrial complex areas: A population-based cohort study

BACKGROUND

Cadmium is known to act as a thyroid disruptor and carcinogen in humans. Recent evidence suggests that cadmium may play a role as a thyroid carcinogen due to its endocrine-disrupting activity, but this characterization remains unclear.

OBJECTIVE

We investigated the association between urinary cadmium and primary thyroid cancer, and the modifying effect of diabetes on this association.

METHODS

We included 5406 participants over 19 years old with measured urinary cadmium from samples collected at eight National Industrial Complex areas from 2003 to 2011. Among 5406 participants, 68 cases were diagnosed with thyroid cancer between enrollment and the end of follow-up (December 31, 2016). Incidence rate ratios for thyroid cancer were estimated using random-effects Cox proportional hazards models with follow-up time as the time scale. In addition, we conducted a stratified analysis by diabetes status.

RESULTS

Compared with the lowest tertile, the middle and highest tertiles had higher risks of thyroid cancer, respectively (HR_{middle vs. lowest} = 1.90, 95% CI = 0.93 to 3.91; HR_{highest vs. lowest} = 2.28, 95% CI = 1.09 to 4.78), with a significant dose-response relationship (P for trend = 0.03). There was no linear association between cadmium level and risk of thyroid cancer. Higher cadmium levels increased thyroid cancer risk in participants without diabetes (HR_{middle vs. lowest} = 2.35, 95% CI = 1.05 to 5.24; HR_{highest vs. lowest} = 2.70, 95% CI = 1.18 to 6.19); although, an association between cadmium levels and thyroid cancer risk in participants with diabetes was not found.

CONCLUSION

Low-level exposure to cadmium is associated with thyroid cancer risk. Our results provide the evidence to limit exposure to cadmium for cancer prevention in the general population. Further studies are needed to investigate the consequence of diabetes and antidiabetic drugs between cadmium and thyroid cancer.

Ethnic Differences of Urinary Cadmium in Cigarette Smokers from the Multiethnic Cohort Study

The Multiethnic Cohort Study (MEC) has demonstrated racial/ethnic differences in smoking-associated lung cancer risk. As part of the ongoing effort to characterize exposure to cigarette smoke constituents and better understand risk differences, we evaluated Cd exposure as it is a known lung carcinogen. We quantified urinary cadmium (Cd) by inductively coupled plasma mass spectrometry in a subset of 1956 current smokers from MEC. Ethnic-specific geometric means (GM) were compared adjusting for age at urine collection, sex, creatinine (natural log), education, and smoking (urinary total nicotine equivalents [TNE] and smoking duration). Self-reported questionnaire data, including occupation, were also considered. Latinos and Native Hawaiians had the highest GM urinary Cd (0.871 and 0.836 ng/mL, respectively) followed by Japanese Americans and African Americans (0.811 ng/mL and 0.807, respectively) and Whites (0.736 ng/mL). Patterns in race/ethnicity were consistent by sex such that females had the highest GM urinary Cd. When further adjusting for categorical occupational Cd exposure, racial/ethnic differences of Cd remained (p = 0.009). Findings suggest differences in urinary Cd among smokers across different racial/ethnic groups exist and highlight the importance in considering environmental sources of Cd exposure beyond smoking. These finding lay ground for future studies of individual characteristics that are associated with lower risk for cancer despite higher carcinogenic exposures.

Prepubertal exposure to high dose of cadmium induces hypothalamic injury through transcriptome profiling alteration and neuronal degeneration in female rats

Cadmium (Cd) is a toxic metal, which seems to be crucial during the prepubertal period. Cd can destroy the structural integrity of the blood-brain barrier (BBB) and enters into the brain. Although the brain is susceptible to neurotoxicity induced by Cd, the effects of Cd on the brain, particularly hypothalamic transcriptome, are still relatively poorly understood. Therefore, we investigated the molecular effects of Cd exposure on the hypothalamus by profiling the transcriptomic response of the hypothalamus to high dose of Cd (25 mg/kg bw/day cadmium chloride (CdCl₂)) during the prepubertal period in Sprague-Dawley female rats. After sequencing and annotation, differential expression analysis revealed 1656 genes that were differentially expressed that 108 of them were classified into 37 transcription factor (TF) families. According to gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, these differentially expressed genes (DEGs) were involved in different biological processes and neurological disorders including Alzheimer's disease (AD), Huntington's disease (HD), and Parkinson's disease (PD), prolactin signaling pathway, PI3K/Akt signaling, and dopaminergic synapse. Five transcripts were selected for further analyses with Real-time quantitative PCR (RT-qPCR). The RT-qPCR results were mostly consistent with those from the high throughput RNA sequencing (RNA-seq). Cresyl violet staining clearly showed an increased neuronal degeneration in the dorsomedial hypothalamus (DMH) and arcuate (Arc) nuclei of the CdCl₂ group. Overall, this study demonstrates that prepubertal exposure to high doses of Cd induces hypothalamic injury through transcriptome profiling alteration in female rats, which reveals the new mechanisms of pathogenesis of Cd in the hypothalamus.

Erythrocyte levels of cadmium and lead and risk of B-cell non-Hodgkin lymphoma and multiple myeloma

Cadmium and lead are persistent environmental toxins that are known or probable carcinogens, based on evidence for causality for nonhematologic cancers. Associations of these metals with risk of non-Hodgkin lymphoma (NHL) and multiple myeloma (MM) are unknown but biologically plausible. To examine the associations of circulating levels of lead and cadmium exposure with risk of B-cell NHL (B-NHL) and multiple myeloma, we conducted a nested case-control study among 299 incident B-cell NHLs and 76 MM cases within the Cancer Prevention Study-II Nutrition Cohort (CPS-II NC). Each case was incidence-density matched to two eligible controls on age, race, sex and blood draw date. Conditional logistic regression was used to estimate relative risks (RR) and 95% confidence intervals (CI) for lymphoid malignancies overall and stratified by subtype. We observed a significant positive association between high erythrocyte lead concentration and risk of lymphoid malignancies overall (RR = 1.16, 95% CI: 1.02-1.33 per 17.6 μg/L (1 standard deviation [SD])) and follicular lymphoma in particular (RR = 1.80, 95% CI: 1.15-2.80 per SD). In contrast, there was no association between erythrocyte cadmium and risk of B-NHL (RR = 0.89, 95% CI: 0.75-1.06 per 0.37 μg/L [1 SD]), or any B-NHL subtypes; but a strong inverse association with MM risk (RR = 0.59, 95% CI: 0.38-0.89, per SD). Results from our study suggest a positive association between erythrocyte lead level and risk of lymphoid malignancies and a possible inverse association between cadmium and myeloma. Additional research is needed to confirm and further explore these findings.

Cadmium and Lead Exposure, Nephrotoxicity, and Mortality

The present review aims to provide an update on health risks associated with the low-to-moderate levels of environmental cadmium (Cd) and lead (Pb) to which most populations are exposed. Epidemiological studies examining the adverse effects of coexposure to Cd and Pb have shown that Pb may enhance the nephrotoxicity of Cd and vice versa. Herein, the existing tolerable intake levels of Cd and Pb are discussed together with the conventional urinary Cd threshold limit of 5.24 μg/g creatinine. Dietary sources of Cd and Pb and the intake levels reported for average consumers in the U.S., Spain, Korea, Germany and China are summarized. The utility of urine, whole blood, plasma/serum, and erythrocytes to quantify exposure levels of Cd and Pb are discussed. Epidemiological studies that linked one of these measurements to risks of chronic kidney disease (CKD) and mortality from common ailments are reviewed. A Cd intake level of 23.2 μg/day, which is less than half the safe intake stated by the guidelines, may increase the risk of CKD by 73%, and urinary Cd levels one-tenth of the threshold limit, defined by excessive ß₂-microglobulin excretion, were associated with increased risk of CKD, mortality from heart disease, cancer of any site and Alzheimer's disease. These findings indicate that the current tolerable intake of Cd and the conventional urinary Cd threshold limit do not provide adequate health protection. Any excessive Cd excretion is probably indicative of tubular injury. In light of the evolving realization of the interaction between Cd and Pb, actions to minimize environmental exposure to these toxic metals are imperative.

Statistical Assessment of Toxic and Essential Metals in the Serum of Female Patients with Lung Carcinoma from Pakistan

Lung cancer (LC) is the number one cancer killer of women both in the USA and around the world. Besides cigarette smoking, an important feature in the etiology of LC is its strong association with exposure of toxic metals. The primary objective of the present investigation was to assess the concentrations of toxic/essential elements (Ni, Ca, Se, Zn, Co, K, Cr, As, Cu, Na, Fe, Hg, Cd, Mg, Mn, and Pb) in the serum samples of LC female patients with female controls by atomic absorption spectrometry after wet-acid digestion procedure. Carcinoembryonic antigen (CEA) was also measured in the serum of the patients using immunoradiometric method. Comparative appraisal of the data revealed that concentrations of Cr, Mg, Cd, Pb, Hg, As, and Ni were noted to be high significantly in serum of LC female patients, while the average Fe, Co, Mn, Na, K, Zn, Ca, and Se were observed at higher levels in female controls (p < 0.05). The correlation study revealed significantly different mutual associations among the elements in the both donor groups. Markedly, variations in the elemental levels were also noted for different types (non-small cell lung cancer and small cell lung cancer) and stages (I, II, III, & IV) of LC patients. Multivariate analyses showed substantially diverse apportionment of the metals in the female patients and female controls. Hence, present findings suggest that the toxic and essential metals accumulated in the body may pose a high risk for LC progression in Pakistani females.

Lifetime Cadmium Exposure and Mortality for Renal Diseases in Residents of the Cadmium-Polluted Kakehashi River Basin in Japan

Very few studies have investigated the dose–response relationship between external cadmium (Cd) exposure and mortality. We aim to investigate the relationship between lifetime Cd intake (LCd) and mortality in the Cd-polluted Kakehashi River basin in Japan. Mortality risk ratios for a unit of increase of LCd and urinary Cd were analyzed using Cox’s proportional model. LCd was estimated based on residency and Cd in rice produced in their living areas. In men, mortality for all causes was significantly increased for a 10-μg/g Cr increase in urinary Cd, but not for a 1-g increase in LCd. In women, mortality risks for all causes and renal diseases, particularly renal failure, were significantly increased for a 10-μg/g Cr increase in urinary Cd. Similarly, mortality risks for renal diseases and renal failure were significantly increased for a 1-g increase of LCd in women. Comparing the contribution of two exposure markers to increased mortality in women, LCd was more effective for increasing mortality risks for renal diseases and renal failure, while urinary Cd contributed more to increased mortality risk for all causes. LCd may show a better dose–response relationship with mortality risk for renal diseases in women.

Evidence of selected nephrotoxic elements in Sri Lankan human autopsy bone samples of patients with CKDu and controls

Background

This article describes the analysis and interpretation of data relating to the presence of cadmium, lead, mercury and fluoride in human bone samples obtained from cadavers of patients dying of Chronic Kidney Disease of uncertain aetiology (CKDu) in a case-control study, which the authors believe to be the first in Sri Lanka.

Methods

This is a case-control study comparing selected nephrotoxins levels in autopsy samples of bones from persons confirmed to have died of CKDu, and who had lived in a CKDu hotspot and controls with no history of abnormal kidney functions who had lived in areas having a low prevalence of CKDu.

Results

The average age at death of the cases was 59.6 ± 15.1 (±SD), while that for controls was 58.0 ± 19.3 (±SD) years with no significant statistical difference. Calcium adjusted bone lead and bone fluoride levels were significantly higher among CKDu cases (n = 14) than those of controls (n = 33). Further, younger and older clusters of CKDu cases can be differentiated when the calcium adjusted lead content was considered. Younger patients reported higher lead content compared to the older group. Cadmium and mercury content did not show a remarkable difference among cases and controls.

Conclusions

Our results show a significant accumulation of lead in bone tissue in persons who have died of CKDu which indicates a higher chronic exposure of the CKDu victims, to lead. Fluoride content in the bones of cases is also significantly high. The results indicate that a gradual reduction of glomerular filtration rate (GFR) may have occurred with the chronic exposure to lead. At a certain point of the threshold of low GFR, excretion of fluoride may be impaired, since the main excretory pathway of fluoride is via the kidneys. Fluoride accumulation in blood in turn may exacerbate nephrotoxicity, triggering a synergistic cascade of events which may lead to a further deterioration in the GFR. The extremely high fluoride content detected suggests a cumulative effect in people exposed to comparatively higher fluoride levels, most probably from drinking water.

Cadmium exposure and risk of breast cancer: A dose-response meta-analysis of cohort studies

BACKGROUND

Cadmium is a toxic heavy metal that has been implicated in breast cancer etiology, albeit with inconsistent results.

OBJECTIVE

To investigate the shape of the relation between cadmium exposure and breast cancer incidence and mortality in cohort studies.

DATA SOURCES

Following a literature search through April 14, 2020, we carried out a systematic review and dose-response meta-analysis to investigate the shape of the relation between cadmium exposure (assessed either through diet or urine excretion) and disease incidence and mortality.

STUDY ELIGIBILITY CRITERIA

For inclusion, a study had to report incidence or mortality for breast cancer according to baseline cadmium exposure category; be a prospective cohort, case-cohort or nested case-control study with a minimum one-year follow-up, and reporting effect estimates for all exposure categories.

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies were evaluated using the ROBINS-E risk of bias tool. The effects in humans were assessed quantitatively using one-stage dose-response meta-analysis in a random effects meta-analytical model.

RESULTS

We identified 10 studies eligible for inclusion in the dose-response meta-analysis, six based on cadmium dietary intake, and four on urinary excretion levels. We found a marginal and imprecise positive relation between dietary cadmium intake and breast cancer, and no association when urinary cadmium excretion was used for exposure assessment. Compared to no exposure, at 20 µg/day of cadmium intake the summary risk ratio was 1.12 (95% confidence interval 0.80-1.56), while at 2 µg/g creatinine of cadmium excretion the summary risk ratio was 0.89 (95% confidence interval 0.38-2.14). Analysis restricted to post-menopausal women showed no association between either dietary or urinary cadmium and subsequent breast cancer incidence and mortality.

LIMITATIONS AND CONCLUSIONS

Overall, we found scant evidence of a positive association between cadmium and breast cancer. Available data were too limited to carry out stratified analyses according to age, smoking and hormone receptor status. Therefore, possible associations between cadmium exposure and breast cancer in selected subgroups cannot be entirely ruled out.

Urinary cadmium and timing of menarche and pubertal development in girls

BACKGROUND

Cadmium (Cd) is a developmental toxicant that is released into the environment during industrial processes. Previous animal studies suggest that Cd may impact the onset of puberty.

OBJECTIVES

To determine whether Cd exposure, measured as urinary Cd concentration, was associated with ages at menarche and pubertal development.

METHODS

A cohort of 211 girls, ages 10-13 years at baseline, was followed for up to two years. Girls completed an interview and self-assessment of Tanner stages of breast development and pubic hair growth. They were followed monthly until menarche. Urinary Cd concentrations were measured in overnight urine specimens. Multivariable Cox regression was used to evaluate the association between urinary Cd and age at menarche and cumulative logit regression was used to evaluate the associations between urinary Cd and breast development and pubic hair growth.

RESULTS

The baseline geometric mean creatinine-adjusted Cd concentration was 0.22 μg/g creatinine (geometric standard deviation = 1.6) and decreased with increasing age (p-trend = 0.04). Cd levels were higher among Asian than White girls or girls of other/mixed race/ethnicity (p = 0.04). In multivariable analyses, girls with urinary Cd ≥ 0.4 μg/L were less likely to have attained menarche than girls with urinary Cd < 0.2 μg/L (hazard ratio = 0.42; 95% confidence interval, 0.23-0.78). Urinary Cd was negatively associated with pubic hair growth (p-trend = 0.01) but not with breast development (p-trend = 0.72) at baseline.

CONCLUSIONS

These findings suggest that a higher Cd body burden may delay some aspects of pubertal development among girls.

Disparities in Trace Metal Levels in Hodgkin/Non-Hodgkin Lymphoma Patients in Comparison with Controls

Lymphoma arises from cells of the immune system and trace metals augment the immune system and their imbalance may promote immunological disorders including tumorigenesis. The primary aim of the present investigation was to evaluate the levels of essential/toxic trace metals in the nails of non-Hodgkin and Hodgkin lymphomas patients in comparison with controls. The samples collected from patients and controls were digested in the mixture of HNO₃-HClO₄ and selected trace metals were analysed using flame atomic absorption spectrometry. The results showed that mean concentrations of some elements (Pb, Ni, Cd, Cu and Cr) in nails of non-Hodgkin lymphoma patients were significantly elevated (p < 0.05) than that of the controls whereas mean contents of Pb, Cu, Cd and Cr were observed to be significantly higher in the nails of Hodgkin lymphoma patients compared with healthy donors. Additionally, correlation study pointed out significantly diverse mutual associations of the trace metals among the patients and controls. The present results revealed noticeable disparities in the metal concentrations based on gender, food habits, tobacco use and types/stages of the donor's groups. Overall, the pathogenesis of disease significantly affected the trace metal balance in both patients' groups.

Epidemiological study of kidney health in an area with high levels of soil cadmium and selenium: Does selenium protect against cadmium-induced kidney injury?

Chronic exposure to cadmium (Cd) can cause renal dysfunction. Studies of animals, cell cultures, and plants have found that selenium (Se) can effectively alleviate the hazard generated by Cd, but there has been little study of this in general human populations. This study recruited 313 subjects from China's Hubei Province, including 160 living in areas with high soil Cd and Se (exposure group) and 153 living in clean areas (control group). The levels of the following were detected: Cd and Se in blood (B-Cd and B-Se), urine (U-Cd and U-Se), and hair (H-Cd and H-Se); N-acetyl-β-D-glucosaminidase (U-NAG), β₂-microglobulin (U-β₂-MG), and albumin (U-ALB) in urine; and malondialdehyde (S-MDA), superoxide dismutase (S-SOD), and glutathione peroxidase (S-GSH-Px) in serum. In addition, the interactions between Cd and Se were assessed. The median levels of B-Cd, B-Se, U-Cd, U-Se, H-Cd, H-Se, S-MDA, and S-GSH-Px of exposure group (2.60 ng/mL, 238.90 ng/mL, 3.13 μg/g Cr, 45.43 μg/g Cr, 0.06 μg/g, 0.70 μg/g, 5.22 nmol/mL, and 308.89 U, respectively) were significantly higher than of controls (0.95 ng/mL, 130.50 ng/mL, 1.08 μg/g Cr, 30.51 μg/g Cr, 0.04 μg/g, 0.49 μg/g, 4.71 nmol/mL, and 267.54 U, respectively), but there were no significant differences in U-NAG, U-β₂-MG, U-ALB, or S-SOD between the two groups. U-NAG levels were significantly negatively associated with the interaction between Cd and Se (B: -0.511, 95% CI: -0.886, -0.136). Additionally, changes in the direction of the estimated regression coefficient in the low and high H-Se groups were observed for U-Cd and S-MDA (from 0.018 to -0.090), U-Cd and S-GSH-Px (from -0.039 to 0.101). This study found that populations living in areas with high levels of soil Cd and Se did not show greater Cd-induced renal tubular and glomerular injuries than the control population, which could attribute to the protective effects of Se. The protective effects may be related to the peculiar function of Se that Se can combine with free Cd to activate the antioxidant enzyme system.

Disparities in the Concentrations of Essential/Toxic Elements in the Blood and Scalp Hair of Lymphoma Patients and Healthy Subjects

Lymphoma is one of the fastest growing malignancies worldwide and imbalance in the concentrations of trace elements can play a significant role in the onset and progression of the disease. Selected essential and toxic elements (Fe, Zn, Cu, Mn, Ni, Cr, Cd and Pb) were analysed in the blood & scalp hair of lymphoma patients (n = 59 & 58, respectively) and controls (n = 61 & 60, respectively) by atomic absorption spectrometry. On the average, Ni, Cr, Cu and Cd revealed significantly higher contents in the blood and scalp hair of the patients than the controls (p < 0.05). The correlation study showed significantly diverse relationships among the elements in blood & scalp hair of the two donor groups. Variations in the elemental levels with different types of lymphoma (non-Hodgkin and Hodgkin) were also evaluated. Disparities in the elemental concentrations were also investigated for various types of non-Hodgkin (diffuse large B-cell lymphoma, follicular lymphoma and peripheral T-cell lymphoma) and Hodgkin lymphoma (mixed cellularity, nodular lymphocyte predominant and nodular sclerosing), as well as for different stages (I, II, III & IV) of the cancer. Multivariate statistical analysis showed considerably divergent associations of the elements in the patients and controls. The study indicated profound alteration of the elemental levels in the patients; it may be implicated in elemental-induced disorders including lymphoma.

A correlation study of BK Polyoma Virus infection and prostate Cancer among Sudanese patients - immunofluorescence and molecular based case-control study

Background

Polyomavirus hominis1, also called BK virus (BKV) is a well-known etiological agent of renal transplant nephropathy and cystitis. Recently, it got great attention from the researcher as a principal predisposing factor for different kinds of cancers including prostate cancer (PCa). Thus, this study aims to determine the correlation between BKV infection and PCa through a descriptive case-control based study.

Methods

A total of 55 paraffin-embedded tissue blocks of patients with PCa and another 55 tissue blocks from BPH patients were obtained. In parallel, respective urine samples were collected from all the cases and controls. The existence of BKV large T antigen (LTAg) was analyzed by Direct Immunofluorescence assay. Only BKV LTAg positive specimens were further analyzed for the presence of viral DNA by using a conventional PCR then subjected to viral load quantitation by using Q-PCR.

Result

BKV LTAg was identified in 30% (17/55) of cases tissue specimens and only in 7% (4/55) of the controls tissue specimens with P-value 0.002 and Odd ratio 5.7. The conventional PCR detects the BKV DNA in 16 out of 17 cases specimens while only two out of four controls specimens were identified with a viral DNA. The mean of the BKV DNA load was higher significantly among cases 6733 ± 6745 copies/ml when compared to controls 509.0 ± 792.9 copies/m with a p-value of 0.002.

Conclusion

More BKV prevalence with high viral load was observed in PCa patients tissue compared to BPH specimens. PCa Gleason scores 9 and 7 were the most cancer grades identified with the presence of BKV DNA. Our findings are thus consistent with a significant link between the BKV infection and the PCa risk. Prostate or seminal fluids should be selected as principal specimens for future studies and can, therefore, be designated as screening samples to find early virus evidence in the prostate tissue. Detection of early virus evidence may help to reduce the risk of PCa cancer due to BKV.

Environmental cadmium exposure and pancreatic cancer: Evidence from case control, animal and in vitro studies

Although profoundly studied, etiology of pancreatic cancer (PC) is still rather scarce. Some of established risk factors of PC are connected to an increased cadmium (Cd) body burden. Hence, the aim of this study was to investigate the role of this environmental pollutant in PC development by conducting human observational, experimental and in vitro studies. The case-control study included 31 patients with a histologically based diagnosis of exocrine PC subjected to radical surgical intervention as cases and 29 accidental fatalities or subjects who died of a nonmalignant illness as controls. Animal study included two treated groups of Wistar rats (15 and 30 mg Cd/kg b.w) and untreated control group, sacrificed 24 h after single oral exposure. In in vitro study pancreas hTERT-HPNE and AsPC-1 cells were exposed to different Cd concentrations corresponding to levels measured in human cancerous pancreatic tissue. Cd content in cancer tissue significantly differed from the content in healthy controls. Odds ratio levels for PC development were 2.79 (95% CI 0.91-8.50) and 3.44 (95% CI 1.19-9.95) in the third and fourth quartiles of Cd distribution, respectively. Animal study confirmed Cd deposition in pancreatic tissue. In vitro studies revealed that Cd produces disturbances in intrinsic pathway of apoptotic activity and the elevation in oxidative stress in pancreatic cells. This study presents three different lines of evidence pointing towards Cd as an agent responsible for the development of PC.

A quantitative analysis of chronic exposure of selected heavy metals in a model diet in a CKD hotspot in Sri Lanka

BACKGROUND

Evidence of chronic low levels of exposure to heavy metals in Sri Lanka has emerged in a number of studies carried out in the recent past. The source and magnitude of such exposures have to be understood in order to assess the risk of adverse health effects of this exposure and to propose suitable public health interventions.

METHODS

An assessment was carried out to quantify chronic exposure to cadmium, lead and arsenic through food in people living in an area in Sri Lanka, where prevalence of Chronic Kidney Disease of unknown origin (CKDu) is highest. First a dietary survey was carried out in the subjects to estimate the type and quantity of typical food items in order to estimate an average consumption. A model diet was formulated using this dietary consumption data; and this was thereafter used for estimation of chronic dietary exposure of selected contaminants. In parallel, the levels of contaminants of interest in the various identified food items: cadmium, lead and arsenic, were determined.

RESULTS

Assuming the major route of intake is food, and based on the quantity and type of food items consumed, a 60 kg man is exposed to average doses of 83.7 μg cadmium, 924.1 μg lead, and 180.3 μg arsenic per week. The impact of chronic lead exposure was affirmed by a mean blood lead level of 3.0 μg/dL, with a maximum level of 8.8 μg/dL being observed in some cases.

CONCLUSIONS

Chronic low dose exposure of lead from food appears to be a public health concern in the studied population. Cadmium exposure through food appears to be of concern also. However, arsenic exposure through food appears to be within safe limits. As there are numbers of possible adverse health outcomes that can be associated with such estimated exposures of heavy metals, public health interventions are warranted to limit the described harmful exposures. Advocacy on dietary patterns and agronomic practices to lower the contaminants identified are the two broad strategies suggested.

A quantitative analysis of chronic exposure of selected heavy metals in a model diet in a CKD hotspot in Sri Lanka

Background

Evidence of chronic low levels of exposure to heavy metals in Sri Lanka has emerged in a number of studies carried out in the recent past. The source and magnitude of such exposures have to be understood in order to assess the risk of adverse health effects of this exposure and to propose suitable public health interventions.

Methods

An assessment was carried out to quantify chronic exposure to cadmium, lead and arsenic through food in people living in an area in Sri Lanka, where prevalence of Chronic Kidney Disease of unknown origin (CKDu) is highest. First a dietary survey was carried out in the subjects to estimate the type and quantity of typical food items in order to estimate an average consumption. A model diet was formulated using this dietary consumption data; and this was thereafter used for estimation of chronic dietary exposure of selected contaminants. In parallel, the levels of contaminants of interest in the various identified food items: cadmium, lead and arsenic, were determined.

Results

Assuming the major route of intake is food, and based on the quantity and type of food items consumed, a 60 kg man is exposed to average doses of 83.7 μg cadmium, 924.1 μg lead, and 180.3 μg arsenic per week. The impact of chronic lead exposure was affirmed by a mean blood lead level of 3.0 μg/dL, with a maximum level of 8.8 μg/dL being observed in some cases.

Conclusions

Chronic low dose exposure of lead from food appears to be a public health concern in the studied population. Cadmium exposure through food appears to be of concern also. However, arsenic exposure through food appears to be within safe limits. As there are numbers of possible adverse health outcomes that can be associated with such estimated exposures of heavy metals, public health interventions are warranted to limit the described harmful exposures. Advocacy on dietary patterns and agronomic practices to lower the contaminants identified are the two broad strategies suggested.

Profiling of differentially expressed genes in cadmium-induced prostate carcinogenesis

The aim of the present study was to investigate the genetic signatures of cadmium-transformed prostate epithelial (CTPE) cells and to identify the potential molecular signaling involved in their malignant transformation. The dataset contained normal prostate epithelial (RWPE-1) and CTPE cells. To further examine the biological functions of the identified differentially expressed genes (DEGs), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Reactome pathway enrichment analyses were performed. In total, 2357 DEGs were identified, including 1083 upregulated genes and 1274 downregulated genes. GO, KEGG, and Reactome pathway enrichment analyses indicated that upregulated genes were significantly enriched in ECM-receptor, focal adhesion, TGFβ signaling, and syndecan interactions, while downregulated genes were mainly involved in cell cycle regulation, arachidonic acid metabolism, oxidative phosphorylation, and folate biosynthesis (p < .05). The top upregulated (SATB1 (p < .0001), EYA2 (p < .0001) and KPNA7 (p < .0027)) and downregulated (PITX2 (p < .0007), PDLIM4 (p < .0020) and FABP5 (p < .0007)) genes were further validated via qRT-PCR analysis. In conclusion, the present study profiled DEGs in RWPE-1 and CTPE cells and identified gene pathways that may be associated with malignant transformation and tumor progression.

Induction of endoplasmic reticulum stress might be responsible for defective autophagy in cadmium-induced prostate carcinogenesis

Earlier, we reported that chronic cadmium (Cd)-exposure to prostate epithelial (RWPE-1) cells causes defective autophagy, which leads to the transformation of a malignant phenotype in both in vitro and in vivo models. However, the upstream events responsible for defective autophagy are yet to be delineated. The present study suggests that chronic Cd exposure induces endoplasmic reticulum (ER) stress that triggers the phosphorylation of stress transducers [protein kinase R-like ER Kinase- (PERK), eukaryotic translation initiation factor 2-alpha- (eIF2-α) and Activating Transcription Factor 4 -(ATF-4)], resulting in defective autophagy that protects Cd-exposed RWPE-1 cells. On the other hand, inhibition of the ATF4 stress inducer by siRNA blocked the Cd-induced defective autophagy in transforming cells. While dissecting the upstream activators of ER stress, we found that increased expression of reactive oxygen species (ROS) is responsible for ER stress in Cd-exposed RWPE-1 cells. Overexpression of antioxidants (SOD1/SOD2) mitigates Cd-induced ROS that results in inhibition of ER stress and autophagy in prostate epithelial cells. These results suggest that the induction of ROS and subsequent ER stress are responsible for defective autophagy in Cd-induced transformation in prostate epithelial cells.

Oral cadmium exposure affects skin immune reactivity in rats

Skin can acquire cadmium (Cd) by oral route, but there is paucity of data concerning cutaneous effects of this metal. Cd acquired by oral route can affect skin wound healing, but the effect of Cd on other activities involved in skin homeostasis, including skin immunity, are not explored. Using the rat model of 30-day oral administration of Cd (5 ppm and 50 ppm) in drinking water, basic aspects of immune-relevant activity of epidermal cells were examined. Dose-dependent Cd deposition in the the skin was observed (0.035 ± 0.02 µg/g and 0.127 ± 0.04 µg/g at 5 ppm and 50 ppm, respectively, compared to 0.012 ± 0.009 µg/g at 0 ppm of Cd). This resulted in skin inflammation (oxidative stress at both Cd doses and dose-dependent structural changes in the skin and the presence/activation of innate immunity cells). At low Cd dose inflammatory response (nitric oxide and IL-1β) was observed. Other inflammatory cytokines (IL-6 and TNF) response occurred at 50 ppm, which was increased further following skin sensitization with contact allergen dinitro-chlorobenzene (DNCB). Epidermal cells exposed to both Cd doses enhanced concanavalin A (ConA)-stimulated lymphocyte production of IL-17. This study showed for the first time the effect of the metal which gained access to the skin via gut on immune reactivity of epidermal cells. Presented data might be relevant for the link between dietary Cd and the risk of skin pathologies.

Effects of salicylic acid, Epi-brassinolide and calcium on stress alleviation and Cd accumulation in tomato plants

Salicylic acid (SA), Epi-brassinolide (EBL) and calcium (Ca) play crucial roles in plant development and mediate plant response to biotic and abiotic stress. This study was aimed to investigate the possible mediatory role of SA, EBL, Ca or their combination in protecting tomato plants from cadmium (Cd) toxicity. According to the results, Cd stress resulted in a significant reduction of plant dry mass, photosynthetic pigment content as well as photosynthetic rate. Exogenous application of SA decreased the malondialdehyde (MDA) level by 39.27% and increased catalase (CAT) activity by 81.17%. SA and EBL treatment significantly increased chlorophyll a (Chl a), chlorophyll b (Chl b) content, photosynthetic rate (Pn) as well as water use efficiency (WUE). SA+EBL (1:1)/Ca+SA+EBL (1:1:1) treatment obviously alleviated Cd-induced growth inhibition, the dry mass of different tomato organs were significantly increased (p < 0.05). Especially in Ca+SA+EBL treated plants, the dry mass of roots, stems and leaves increased by 141.18%, 128.57% and 118.52%, respectively. Besides, SA+EBL and Ca+SA+EBL treatments reduced the MDA level, but increased photosynthetic pigment concentration and photosynthetic efficiency. CAT activity was increased by 62.92% in Ca+SA+EBL treated plants, the WUE was increased by 557.76% in SA+EBL pretreated plants. Moreover, exogenous application of SA, SA+EBL and Ca+SA+EBL significantly decreased Cd accumulation in tomato organs (p < 0.05) compared with Cd-stressed plants. Taken together, our results indicated that exogenous application of SA, EBL and Ca individually or in combination could alleviate Cd toxicity in tomato plants, although the extent varies.

Time-dependent response of A549 cells upon exposure to cadmium

Cadmium is considered one of the most harmful carcinogenic heavy metals in the human body. Although many scientists have performed research on cadmium toxicity mechanism, the toxicokinetic process of cadmium toxicity remains unclear. In the present study, the kinetic response of proteome in/and A549 cells to exposure of exogenous cadmium was profiled. A549 cells were treated with cadmium sulfate (CdSO₄ ) for different periods and expressions of proteins in cells were detected by two-dimensional gel electrophoresis. The kinetic expressions of proteins related to cadmium toxicity were further investigated by reverse transcription-polymerase chain reaction and western blotting. Intracellular cadmium accumulation and content fluctuation of several essential metals were observed after 0-24 hours of exposure by inductively coupled plasma mass spectrometry. Fifty-four protein spots showed significantly differential responses to CdSO₄ exposure at both 4.5 and 24 hours. From these proteins, four expression patterns were concluded. Their expressions always exhibited a maximum abundance ratio after CdSO₄ exposure for 24 hours. The expression of metallothionein-1 and ZIP-8, concentration of total protein, and contents of cadmium, zinc, copper, cobalt and manganese in cells also showed regular change. In synthesis, the replacement of the essential metals, the inhibition of the expression of metal storing protein and the activation of metal efflux system are involved in cadmium toxicity.

Urinary Lead Concentration Is an Independent Predictor of Cancer Mortality in the U.S. General Population

Lead is a ubiquitous pollutant that constitutes an environmental hazard worldwide. Although lead has been known as a carcinogenic factor in animal models, its role in human carcinogenesis is still a topic of debate with limited epidemiological evidence. Moreover, the association between urinary lead, as the most non-invasive and accessible way for lead measurement in human, and cancer mortality in general population has never been explored. We addressed this subject using continuous National Health and Nutrition Examination Survey 1999-2010 data and its Mortality Follow-Up Study. Of 5,316 subjects in study population, 161 participants died due to cancer. Cancer-specific mortality was associated with urinary lead levels after multivariable adjustment. Kaplan-Meier survival curve and cubic regression spline analyses indicated that high concentration of urinary lead exhibited significant association with raised death rate of cancer. Despite the marked decrease in environmental lead levels over the past three decades, lead exposure is still the significant determinant of cancer mortality in general population in U.S., and quantification of urinary lead may serve as a non-invasive approach to facilitate biomarker discovery and clinical translational research.

Cancer Mortality in Residents of the Cadmium-Polluted Jinzu River Basin in Toyama, Japan

After 26 years, we followed up 7348 participants in a 1979-1984 health screening survey in the Jinzu River basin, the heaviest cadmium-polluted area in Japan. We assessed the associations of cadmium exposure levels and mortality from cancer and renal damage, indicated by records of proteinuria and glucosuria in the original survey. Mortality risks (hazard ratios) were analyzed using the Cox proportional hazards model, stratified by sex, after adjusting for age, smoking status, and hypertension, as indicated in the original survey records. In men, the adjusted hazard ratio for mortality from lung cancer was significantly lower in individuals residing in an area of historically high cadmium exposure and in subjects with a historical record of proteinuria, glucosuria, and glucoproteinuria. The risk of mortality from prostate cancer was borderline higher in cadmium-exposed men. In women, historical cadmium exposure was not associated with an increased risk of mortality from malignant neoplasms, but the adjusted hazard ratios for death from total malignant neoplasms or from renal and uterine cancers were significantly higher in exposed subjects with a historical record of proteinuria, glucosuria, and glucoproteinuria. These findings suggest that women residing in cadmium-polluted areas who exhibit markers of renal damage may be at risk of dying of cancer.

Epithelial-mesenchymal transition in breast epithelial cells treated with cadmium and the role of Snail

Epidemiological and experimental studies have implicated cadmium (Cd) with breast cancer. In breast epithelial MCF10A and MDA-MB-231 cells, Cd has been shown to promote cell growth. The present study examined whether Cd also promotes epithelial-mesenchymal transition (EMT), a hallmark of cancer progression. Human breast epithelial cells consisting of non-cancerous MCF10A, non-metastatic HCC 1937 and HCC 38, and metastatic MDA-MB-231 were treated with 1 or 3 μM Cd for 4 weeks. The MCF10A epithelial cells switched to a more mesenchymal-like morphology, which was accompanied by a decrease in the epithelial marker E-cadherin and an increase in the mesenchymal markers N-cadherin and vimentin. In both non-metastatic HCC 1937 and HCC 38 cells, treatment with Cd decreased the epithelial marker claudin-1. In addition, E-cadherin also decreased in the HCC 1937 cells. Even the mesenchymal-like MDA-MB-231 cells exhibited an increase in the mesenchymal marker vimentin. These changes indicated that prolonged treatment with Cd resulted in EMT in both normal and cancer-derived breast epithelial cells. Furthermore, both the MCF10A and MDA-MB-231 cells labeled with Zcad, a dual sensor for tracking EMT, demonstrated a decrease in the epithelial marker E-cadherin and an increase in the mesenchymal marker ZEB-1. Treatment of cells with Cd significantly increased the level of Snail, a transcription factor involved in the regulation of EMT. However, the Cd-induced Snail expression was completely abolished by actinomycin D. Luciferase reporter assay indicated that the expression of Snail was regulated by Cd at the promotor level. Snail was essential for Cd-induced promotion of EMT in the MDA-MB-231 cells, as knockdown of Snail expression blocked Cd-induced cell migration. Together, these results indicate that Cd promotes EMT in breast epithelial cells and does so by modulating the transcription of Snail.

The protective role of melatonin in cadmium-induced proliferation of ovarian cancer cells

Cadmium (Cd), a ubiquitous environmental and occupational pollutant, acts as a metalloestrogen to induce cell proliferation. It is suggested that Cd may also contribute to the development of estrogen-related cancers like ovarian cancer which is the most lethal cancer in women. Furthermore, it was shown that melatonin has antiproliferative effect on estradiol (E2)-induced proliferation. The aim of the present study was to evaluate whether melatonin inhibits Cd-induced proliferation in ovarian cancer cell lines and also whether Cd and melatonin can modulate estrogen receptor α (ERα) expression. OVCAR3 and SKOV3 human ovarian cancer cell lines were treated with CdCl₂ (1-100 nM) and melatonin (1 μM) for 48 h. Cell proliferation evaluation was carried out by bromodeoxyuridine (BrdU) incorporation assay. ERα expression was detected by western blotting method 24 h after cell treatment. The results were demonstrated that Cd increased proliferation of ovarian cancer cell lines in a dose dependent manner. Melatonin inhibited Cd-induced proliferation of OVCAR3 and SKOV3 cell lines. Moreover, CdCl₂ significantly increased ERα expression in both OVCAR3 and SKOV3 cell lines compared to control. Melatonin significantly inhibited Cd inducing effect on ERα expression of OVCAR3 and SKOV3 cell. In conclusion, due to the proliferative effect on ovarian cancer cell lines, Cd could play an important role in the etiology of ovarian cancer by inducing cells ERα expression. Furthermore, melatonin has the protective role on Cd-induced cell proliferation by inhibition of ERα expression.

Cadmium Exposure as a Putative Risk Factor for the Development of Pancreatic Cancer: Three Different Lines of Evidence

Although profoundly studied, etiology of pancreatic cancer (PC) is still rather scant. Exposure to cadmium (Cd), a ubiquitous metal associated with well-established toxic and carcinogenic properties, has been hypothesized to one putative cause of PC. Hence, we analyzed recently published observational studies, meta-analyses, and experimental animal and in vitro studies with the aim of summarizing the evidence of Cd involvement in PC development and describing the possible mechanisms. Consolidation of epidemiological data on PC and exposure to Cd indicated a significant association with an elevated risk of PC among general population exposed to Cd. Cadmium exposure of laboratory animals was showed to cause PC supporting the findings suggested by human studies. The concordance with human and animal studies is buttressed by in vitro studies, although in vitro data interpretation is problematic. In most instances, only significant effects are reported, and the concentrations of Cd are excessive, which would skew interpretation. Previous reports suggest that oxidative stress, apoptotic changes, and DNA cross-linking and hypermethylation are involved in Cd-mediated carcinogenesis. Undoubtedly, a significant amount of work is still needed to achieve a better understanding of the Cd involvement in pancreatic cancer which could facilitate prevention, diagnosis, and therapy of this fatal disease.

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.

Planarians as models of cadmium-induced neoplasia provide measurable benchmarks for mechanistic studies

Bioassays of planarian neoplasia highlight the potential of these organisms as useful standards to assess whether environmental toxins such as cadmium promote tumorigenesis. These studies complement other investigations into the exceptional healing and regeneration of planarians - processes that are driven by a population of active stem cells, or neoblasts, which are likely transformed during planarian tumor growth. Our goal was to determine if planarian tumorigenesis assays are amenable to mechanistic studies of cadmium carcinogenesis. To that end we demonstrate, by examining both counts of cell populations by size, and instances of mitosis, that the activity of the stem cell population can be monitored. We also provide evidence that specific biomodulators can affect the potential of planarian neoplastic growth, in that an inhibitor of metalloproteinases effectively blocked the development of the lesions. From these results, we infer that neoblast activity does respond to cadmium-induced tumor growth, and that metalloproteinases are required for the progression of cancer in the planarian.

Cadmium exposure and endometrial cancer risk: A large midwestern U.S. population-based case-control study

Estrogen-mimicking chemicals, such as cadmium, may be associated with increased susceptibility to hormone-dependent cancers, though supporting data are sparse, particularly for endometrial cancer. The Health and Environmental Exposure Research (HEER) study worked with the Arkansas Central Cancer Registry, Iowa Cancer Registry and Missouri Cancer Registry to obtain names of women diagnosed with endometrial cancer who were willing to be contacted for participation in our case control study. Voter registration lists from Iowa and Missouri were used to randomly select similarly aged women as represented in the case population. Participants were interviewed by telephone to obtain information on known or suspected endometrial risk factors. Urine kits were sent to participants for home collection and returned for analysis. Our case-control study consisted of 631 incident cases of endometrial cancer diagnosed from January 2010 to October 2012 and 879 age-matched population-based controls, ages 18-81 years (mean age 65 years). We quantified cadmium amounts in urine and standardized these values through creatinine adjustment. Using data from all survey completers, we developed a multivariable model for endometrial cancer. Creatinine-adjusted cadmium concentration was added to this model. Odds ratio (OR) and 95% confidence intervals (CIs) for endometrial cancer were calculated. After multivariable adjustment, higher creatinine-adjusted cadmium exposure was associated with a statistically significant increase of endometrial cancer risk (OR: 1.22; 95% CI: 1.03-1.44). Our results provide evidence that cadmium may increase the risk of endometrial cancer, possibly through estrogenic effects.