Increased risk of cancer mortality associated with cadmium exposures in older Americans with low zinc intake

The overlooked impact of cadmium on the progression of chronic hepatitis and the onset of renal failure in advanced cirrhosis

The mechanism of hepatocyte destruction in chronic hepatitis is not completely understood, while renal failure in individuals with advanced cirrhosis is a significant concern. It is well known that smokers who are chronically infected with hepatitis B and C viruses (HBV, HCV) have a poor prognosis. In the present review, we propose a novel hypothesis that environmental exposure to a nephrotoxic metal pollutant, cadmium (Cd) may contribute to hepatocyte destruction and, subsequently, affect the duration of chronic hepatitis. The metal binding protein, metallothionein (MT) sequesters cadmium as CdMT complexes, and effectively neutralize its adverse effects. Cadmium can cause the damage to hepatocytes, only when it is in an unbound form. In addition to its ability to bind cadmium, MT can act as a scavenger of reactive oxygen species (ROS). However, the cellular MT levels may decrease, when ROS is excessively produced under the pathologic chronic viral hepatitis conditions, especially while the cellular levels of zinc may also be low. Zinc is an endogenous inducer of MT, and is required for maximal MT expression. High ROS levels in the hepatocytes diminishes MT binding to metals. Consequently, the proportion of unbound Cd is increased and thus there is more hepatic damage. Hepatic damage leads to a copious release of CdMT into the circulation. This significant cadmium load, which occurs after hepatic damage, and in some cases, muscle atrophy, induces kidney damage with resultant renal failure in advanced cirrhosis.

Modulation of Adverse Health Effects of Environmental Cadmium Exposure by Zinc and Its Transporters

Zinc (Zn) is the second most abundant metal in the human body and is essential for the function of 10% of all proteins. As metals cannot be synthesized or degraded, they must be assimilated from the diet by specialized transport proteins, which unfortunately also provide an entry route for the toxic metal pollutant cadmium (Cd). The intestinal absorption of Zn depends on the composition of food that is consumed, firstly the amount of Zn itself and then the quantity of other food constituents such as phytate, protein, and calcium (Ca). In cells, Zn is involved in the regulation of intermediary metabolism, gene expression, cell growth, differentiation, apoptosis, and antioxidant defense mechanisms. The cellular influx, efflux, subcellular compartmentalization, and trafficking of Zn are coordinated by transporter proteins, solute-linked carriers 30A and 39A (SLC30A and SLC39A), known as the ZnT and Zrt/Irt-like protein (ZIP). Because of its chemical similarity with Zn and Ca, Cd disrupts the physiological functions of both. The concurrent induction of a Zn efflux transporter ZnT1 (SLC30A1) and metallothionein by Cd disrupts the homeostasis and reduces the bioavailability of Zn. The present review highlights the increased mortality and the severity of various diseases among Cd-exposed persons and the roles of Zn and other transport proteins in the manifestation of Cd cytotoxicity. Special emphasis is given to Zn intake levels that may lower the risk of vision loss and bone fracture associated with Cd exposure. The difficult challenge of determining a permissible intake level of Cd is discussed in relation to the recommended dietary Zn intake levels.

Is Chronic Kidney Disease Due to Cadmium Exposure Inevitable and Can It Be Reversed?

Cadmium (Cd) is a metal with no nutritional value or physiological role. However, it is found in the body of most people because it is a contaminant of nearly all food types and is readily absorbed. The body burden of Cd is determined principally by its intestinal absorption rate as there is no mechanism for its elimination. Most acquired Cd accumulates within the kidney tubular cells, where its levels increase through to the age of 50 years but decline thereafter due to its release into the urine as the injured tubular cells die. This is associated with progressive kidney disease, which is signified by a sustained decline in the estimated glomerular filtration rate (eGFR) and albuminuria. Generally, reductions in eGFR after Cd exposure are irreversible, and are likely to decline further towards kidney failure if exposure persists. There is no evidence that the elimination of current environmental exposure can reverse these effects and no theoretical reason to believe that such a reversal is possible. This review aims to provide an update on urinary and blood Cd levels that were found to be associated with GFR loss and albuminuria in the general populations. A special emphasis is placed on the mechanisms underlying albumin excretion in Cd-exposed persons, and for an accurate measure of the doses-response relationships between Cd exposure and eGFR, its excretion rate must be normalised to creatinine clearance. The difficult challenge of establishing realistic Cd exposure guidelines such that human health is protected, is discussed.

Assessment of potentially toxic metal(loid)s contamination in soil near the industrial landfill and impact on human health: an evaluation of risk

The generation of solid waste is increasing with each passing day due to rapid urbanization and industrialization and has become a matter of concern for the international community. Leachate leakages from landfills pollute the soil and can potentially harm the human health. In this paper, inductively coupled plasma-optical emission spectrometric studies were employed to assess and analyze the composition of metals (Ba, Cd, Pb, Hg, Cu, Cr and Mn) and metalloid (As) in soil samples. Results of Cr, Mn, Cu, As, Ba, Cd, Pb and Hg from CRM (certified reference material, SRM 2709a) of San Joaquin soil were evaluated and reported in terms of percent recoveries which were in the range of 97.6-102.9% and show outstanding extraction efficiency. Other than copper, where the permitted limit set by the EU is specified as 50-140 mg/kg in soil, the average amount of all the metals in soil was found within the permissible limits provided by WHO, the European Community (EU) and US EPA. Soil contaminated with Hg (PERI = 100) and Cd (PERI = 145.50) posed an ecological risk significantly. Pollution load index (PLI) value is greater than 1, while degree of contamination (Cdeg) value is less than 32 which indicated that the soil is polluted and considerably contaminated with metals and metalloid, respectively. In terms of the average daily dosage (ADD) of soil, children received the highest doses of all metals (ADDing = 1.315 × 10-7 - 2.470 × 10-3 and ADDderm = 9.939 × 10-7 - 5.292 × 10-11), whereas ADDing (1.409 × 10-8 - 2.646 × 10-4) was found greater in adults. For all metals except for Ba, the hazard quotient (HQ) trend in both children and adults was observed to be HQing > HQderm > HQinh of soil. Children who are at the lower edge of cancer risk had a lifetime cancer risk (LCR) of 2.039 × 10-4 for Cr from various paths of soil exposure.

Associations of micronutrients exposure with cadmium body burden among population: A systematic review

BACKGROUND

The absorption and accumulation of cadmium (Cd) within the human body can be influenced by the status of certain micronutrients, while available evidence for the association between micronutrient exposure and Cd body burden remains fragmented and inconsistent. To address this issue, this article reviews and synthesizes epidemiological studies that examine the association between micronutrient exposure and Cd burden in humans, to elucidate the potential association between micronutrient exposure and Cd body burden.

METHODS

We conducted a systematic review of epidemiologic studies reporting the association between micronutrient status and Cd body burden among the population. Relevant articles were selected based on predetermined criteria from PubMed, Web of Science, and Scopus databases published from 2000 to 2021. The exposures that were evaluated included micronutrients (zinc, selenium, iron, calcium, and vitamins) status or intakes of them. The outcome of interest was the Cd body burden as indicated by blood Cd or urinary Cd levels. The quality of included studies was assessed using The Joanna Briggs Institute critical appraisal tool. We extracted data from each article, including study design, study site, study population, micronutrient status, Cd body burden, and the correlations between micronutrient status and Cd body burden.

RESULTS

Our systematic search yielded 1660 articles. Of these, forty-four were selected for inclusion based on prespecified criteria. These selected articles evaluated the relationship between Cd body burden and seven different micronutrients, namely, selenium (Se), zinc (Zn), calcium (Ca), iron (Fe), vitamin A, vitamin B12, and vitamin D. The majority of studies (n = 41) were observational, while only three were randomized controlled trials. Among the seventeen studies assessing Zn status, ten reported a negative association between serum Zn levels or intake and urinary and blood Cd levels. Results were inconsistent among the ten studies examining the association between Se levels and Cd body burden. Six studies showed that Cd in blood and urine was negatively correlated with serum ferritin (SF), a biomarker of body Fe status. Two studies reported a negative correlation between Ca and blood Cd.

CONCLUSIONS

This synthesis of available evidence suggests that certain micronutrients, especially Zn and Fe, may play a role in reducing the Cd body burden among populations. The evidence strongly supports a negative association between Zn, Fe, and Cd body burden, whereas evidence for Se, Ca and vitamins is insufficient to draw definitive conclusions regarding their relationship with Cd body burden. In addition, observational studies limit the ability to infer a causal relationship between micronutrients and Cd body burden, highlighting the need for additional intervention studies. Our review may inform nutrient supplementation guidance, control of Cd body burden, and future research to mitigate the adverse health effects of Cd in the context of global Cd pollution.

Cadmium exposure and the risk of prostate cancer among Nigerian men: effect modification by zinc status

BACKGROUND

Prostate cancer (PCa) may result from an interplay between many factors including exposure to trace elements. This study examined the association between cadmium exposure and PCa among Nigerian men and evaluated possible modification of this effect by zinc status.

METHODS

This case-control study involved men with histologically confirmed PCa (n = 82), benign prostatic hyperplasia (BPH; n = 93) and controls (n = 98), aged between 40 and 80 years. Study participants were recruited from the main teaching hospital that draws clients from the entire Anambra State in South-Eastern Nigeria. Blood and urine samples were collected from these participants and were analyzed for trace elements using ICP-MS. Statistical models were used to assess the exposure risk for cadmium exposure as well as the mediating effect of zinc status.

RESULTS

Among men with prostatic disorders (case-case analysis), every 10-fold increase in urinary cadmium was associated with increased risk of PCa (adjusted odds ratios: 2.526; 95% CI: 1.096-5.821). Men in the highest blood zinc quartile had lower odds of PCa compared to the lowest quartile (AOR: 0.19; 95% CI, 0.06-0.54; p-for trend = 0.001). Zinc-specific effect was observed in this group: every 10-fold increase in urinary cadmium was associated with increased risk of PCa among men with creatinine-adjusted urinary zinc levels below the median value (AOR: 8.46; 95% CI: 1.97 -36.39) but not in those above the median value (AOR: 1.55; 95% CI: 0.45 - 5.39).

CONCLUSION

Higher exposure to cadmium may be associated with increased risk of PCa in Nigeria and probably other countries with high prevalence of Zn deficiency. These results point to the need to consider co-occurring trace metals in any effort to mitigate the toxicity of Cd in the environment.

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.

Associations with Blood Lead and Urinary Cadmium Concentrations in Relation to Mortality in the US Population: A Causal Survival Analysis with G-Computation

Using the parametric g-formula, we estimated the 27-year risk of all-cause and specific causes of mortality under different potential interventions for blood lead (BLLs) and urinary cadmium (UCd) levels. We used data on 14,311 adults aged ≥20 years enrolled in the NHANES-III between 1988 and 1994 and followed up through 31 Dec 31 2015. Time and cause of death were determined from the National Death Index records. We used the parametric g-formula with pooled logistic regression models to estimate the relative and absolute risk of all-cause, cardiovascular, and cancer mortality under different potential threshold interventions for BLLs and UCd concentrations. Median follow-up was 22.5 years. A total of 5167 (36%) participants died by the end of the study, including 1550 from cardiovascular diseases and 1135 from cancer. Increases in BLLs and creatinine-corrected UCd levels from the 5th to the 95th percentiles were associated with risk differences of 4.17% (1.54 to 8.77) and 6.22% (4.51 to 12.00) for all-cause mortality, 1.52% (0.09 to 3.74) and 1.06% (-0.57 to 3.50) for cardiovascular disease mortality, and 1.32% (-0.09 to 3.67) and 0.64% (-0.98 to 2.80) for cancer mortality, respectively. Interventions to reduce historical exposures to lead and cadmium may have prevented premature deaths, especially from cardiovascular disease.

The Serum Levels of the Heavy Metals Cu, Zn, Cd, and Pb and Progression of COPD-A Preliminary Study

There is evidence in previous studies that high levels of heavy metals may play a key role in the development of COPD due to the induction of chronic inflammation and oxidative stress. In this preliminary study, we used atomic absorption spectrophotometry to measure the levels of four heavy metals (Cu, Zn, Cd, and Pb) in blood serum of COPD patients and controls over 2 years. Clinical data on disease progression or absence were collected in patients living in the industrial region of Stara Zagora, Bulgaria. The mean values of Cu in the serum of patients with COPD and the control group were 374.29 ± 15.03 μg/L and 238.55 ± 175.31 μg/L, Zn—2010.435 ± 670.006 μg/L and 1672.78 ± 934.27 μg/L, Cd—0.334 ± 0.0216 μg/L and 0.395 ± 0.110 μg/L and Pb—0.0732 ± 0.009 μg/L and 0.075 ± 0.0153 μg/L. This is probably because these elements are biogenic and are used in the body for its anti-oxidant protection. In fact, it cannot be stated with certainty that elevated levels of Cu and Zn in the environment have a negative impact in COPD patients. There was a trend towards higher levels of the toxicants lead and cadmium in COPD patients compared to the control group of patients. There is a statistically unproven trend toward higher levels of lead and cadmium in COPD patients compared to controls, which to some extent supports our hypothesis that there is a relationship between environmental lead and cadmium levels and the COPD manifested. In COPD patients, a positive correlation was found between BMI and serum Cu levels (r = 0.413, p = 0.005). A higher concentration of serum Cu was found in men with BMI ≥ 30, compared to those with BMI < 30. There is also a positive correlation to a lesser extent between CRP and cadmium (r = 0.380; p = 0.019) and lead (r = 0.452; p = 0.004). The correlation of lead and cadmium with PSA also shows that these elements may also be associated with the presence of inflammatory processes. A significant negative correlation exists between Pb in the serum of patients with COPD and their blood hemoglobin (r = −356; p = 0.028). The results of our study suggest that higher doses of the trace elements Cu and Zn do not always have a negative effect in patients with COPD, while the toxicants Pb and Cd may be involved in COPD exacerbation and can be used as prognostic biomarkers for progression. Further studies are warranted to confirm these preliminary results.

Human Health Risk Assessment due to Heavy Metals in Ground and Surface Water and Association of Diseases With Drinking Water Sources: A Study From Maharashtra, India

BACKGROUND

Contamination of freshwater sources can be caused by both anthropogenic and natural processes. According to Central Pollution Control Board, Maharashtra along with 2 other states, contribute 80% of hazardous waste generated in India, including heavy metal pollution. Hence, it is important to quantify heavy metal concentrations in drinking water sources in such areas.

MATERIALS AND METHODS

Water samples were analyzed for toxic elements (F, As, Cd, Hg, Pb, Ni, Cu, Zn, Mn, and Cr) using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) Agilent 7500. Health risks due to ingestion and dermal contact was assessed. A total of 557 people were randomly selected, with consumers from all 4 types of water sources that is surface water, hand pump, wells, and municipal water. Spot urine samples were collected from 47 people after considering inclusion and exclusion criteria. Urine was collected for estimating mercury and arsenic levels in the study participants.

RESULTS

Arsenic contributes the most health risk from ingestion from water. Among surface water users, 14 people (32%) reported frequent loose stool (P-value < .05) (OR 2.5), and 11 people (23%) reported frequent abdominal pain (OR 1.9). Hand pump and well water users reported frequent abdominal pain (27%) (OR 1.4) and gastric discomfort (31%) (P-value < .05) (OR 3) respectively. The mean value of urinary Hg and As were 4.91 ± 0.280 and 42.04 ± 2.635 µg/L respectively.

CONCLUSION

Frequent loose stool, gastric discomfort, and frequent abdominal pain were associated with the various sources of drinking water. Urine Hg levels were found higher than the NHANES (USA) Survey. It is recommended that frequent monitoring of drinking water should be enforced around the industrial hub, so that appropriate actions can be taken if present in excess.

Potential benefits of joint hypothetical interventions on diet, lead, and cadmium on mortality in US adults

BACKGROUND

Previous studies reported associations between high blood lead levels (BLLs) and urinary cadmium (UCd) concentrations and all-cause and cause-specific mortality. It is hypothesized that these associations are mediated by inflammation; therefore, adherence to an anti-inflammatory diet may mitigate these effects. We sought to estimate the potential effects of joint hypothetical interventions on metals levels and adherence to an anti-inflammatory diet or fruits and vegetables (FV) intake on the expected mortality distributions.

METHODS

We used data on 14,311 adults aged ≥ 20 years enrolled in the NHANES-III between 1988 and 1994 and followed up through Dec 31, 2015. We estimated daily FV servings and adherence to the dietary inflammatory index at baseline using 24-hour dietary recalls. Mortality was determined from the National Death Index records. We used the parametric g-formula with pooled logistic regression models to estimate the absolute risk of all-cause, cardiovascular, and cancer mortality under different hypothetical interventions compared to the natural course (no intervention).

RESULTS

Overall, we observed a decreased mortality risk when intervening to lower metals levels or increasing adherence to an anti-inflammatory diet or the daily FV servings. The joint intervention to lower BLLs and UCd and increase the adherence to the anti-inflammatory diet had the strongest impact on cancer mortality risk (risk difference [RD] = -1.50% (-2.52% to -0.62%)) compared to the joint intervention only on metals levels RD= -0.97% (-1.89 to 0.70). The same pattern of associations was observed for the joint intervention to lower both metals and increased daily FV servings and cardiovascular diseases mortality risk.

CONCLUSION

Higher diet quality may constitute a complementary approach to the interventions to reduce exposures to cadmium and lead to further minimize their effects on mortality. A paradigm shift is required from a pollutant-focused only to a combination with a human-focused approach for primary prevention against these metals.

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.

Heavy Metal Accumulation in Fruits and Vegetables and Human Health Risk Assessment: Findings From Maharashtra, India

BACKGROUND

Vegetables are consumed enormously by humans all over the world. Consumption of contaminated fruits and vegetables is the most likely route of heavy metal exposure. Hence, it is important to quantify heavy metal concentration in frequently consumed fruits and vegetables.

MATERIALS AND METHODS

The main aim of our study is to investigate heavy metal (Pb, Cd, As, and Hg) contamination in 24 different kinds of vegetables and fruits grown in the industrialized city of Solapur, Maharashtra, India. Potential health risks due to the consumption of fruits and vegetables were assessed. Heavy metal concentration and quality of native soil were also determined. Vegetable and fruit samples were analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) Agilent 7500.

RESULTS

The mean concentrations of selected heavy metals in fruits and vegetables analyzed were: Lead (0.17 ± 0.38 mg/kg) > Mercury (0.06 ± 0.09 mg/kg) > Cadmium (0.02 ± 0.007 mg/kg) > Arsenic (0.002 ± 0.003 mg/kg). Among them, garlic showed the highest heavy metal accumulation followed by potato.

CONCLUSION

Overall, vegetables showed higher metal accumulations than fruits. Some vegetables showed alarming levels of human health risk indices such as the Metal Pollution Index (MPI), Health Risk Index (HRI) and Hazard Index (HI), suggesting that reducing the intake amount of these vegetables may lower the adverse health effects.

The environmental impacts of heavy metals in soil, certain plants and wastewater near industrial area of Brahmanbaria, Bangladesh

At various locations around the world, environments are now becoming greatly polluted by heavy metals, while damage is being done to soil and aquatic life with serious implications for humanity as well. Once heavy metals enter the ecosystem, they persist for a long time, and they are very difficult to eliminate. Discharging of industrial wastes enriched with heavy metals substantially pollutes the soil, water, and air. This study investigated the levels of heavy metals around the industrial area of Brahmanbaria, which is located in Chittagong Division, Bangladesh. Samples of soil, wastewater, vegetable, and grass were collected from the industrial area. The heavy metals were quantified using atomic absorption spectroscopy. The heavy metals found in soil were chromium (Cr) 8.2-18.8, lead (Pb) 3.5-18.3, copper (Cu) 4.6-10.8, zinc (Zn) 48.5-273.4, nickel (Ni) 10.06-26.9, and cadmium (Cd) 0.2 mg/kg, respectively. The metal contents in the wastewater were Cr 0.03-0.5, Pb 0.01-0.05, Cu 0.01-0.02, Zn 0.6-11.2, Ni 0.03-0.14, and Cd 0.003 mg/L, respectively. The metal contents in vegetable and grass were Cr 81.5-247.8, Pb 10.3-34.1, Cu 5.5-6.3, Zn 419.8-435.3, and Ni 8.7-15.5 mg/kg, respectively. The amount of metal in the soil, wastewater, and vegetables and grass followed the sequences: Zn > Cr > Ni > Pb > Cu > Cd, Zn > Cr > Ni > Pb > Cu > Cd, and Zn > Cr > Pb > Ni > Cu, respectively. Compared to the WHO guidelines, the soil in the study area was not polluted with Pb, Cu, and Cd but was moderately polluted with Cr, Zn, and Ni. Continual accumulation of metals in the soil, vegetables and grass could pose a serious risk to the environment as well as many life forms.

Cadmium promotes apoptosis and inflammation via the circ08409/miR-133a/TGFB2 axis in bovine mammary epithelial cells and mouse mammary gland

Cadmium is a common environmental heavy metal pollutant that can accumulate over long periods of time and cause disease. Thus, analysis of the molecular mechanisms affected by cadmium in the body could be of great significance for the prevention and treatment of cadmium-related diseases. In this study, flow cytometry, immunofluorescence, transmission electron microscopy, H&E (Hematoxylin Eosin) staining and TUNEL (TdT-mediated dUTP Nick-End Labeling) assays were used to verify that cadmium induced apoptosis and immune responses in bovine mammary epithelial cells (BMECs) and in mouse mammary gland. Isolated BMECs cultured with or without cadmium were collected to screen miRNA (microRNA) using high-throughput sequencing. There were 42 differentially-expressed miRNAs among which 27 were upregulated and 15 downregulated including bta-miR-133a, bta-miR-23b-5p, bta-miR-29e, bta-miR-365-5p, bta-miR-615, bta-miR-7, bta-miR-11975, bta-miR-127, and bta-miR-411a. Among those, miR-133a (which can specifically target TGFB2 (Recombinant Transforming Growth Factor Beta 2) was the most significantly downregulated with a fold-change of 5.27 in BMECs cultured with cadmium. Application of the double luciferase reporter system, western blotting, and qRT-PCR (Quantitative Real-time PCR) revealed that circ08409 can directly bind to miR-133a. Experiments demonstrated that circRNA-08409 could adsorb bta-miR-133a. Both circ08409 and TGFB2 significantly increased apoptosis and altered expression level of a series of inflammatory factors in BMECs. In contrast, miR-133a decreased significantly apoptosis and inflammation in the cells. Compared with cultures receiving only cadmium, the miR-133a+cadmium cultures exhibited significant reductions in the occurrence of late apoptosis. Overall, results indicated that circ08409 could relieve the inhibitory effect of miR-133a on TGFB2 expression by combining with miR-133a and subsequently modulating cell proliferation, apoptosis and inflammation. Overall, the data suggested that the circ08409/miR-133a/TGFB2 axis might play a role in mediating the effect of cadmium on BMECs. As such, data provide novel insights into controlling hazards that cadmium could induce in the mammary gland.

Toxic and heavy metals contamination assessment in soil and water to evaluate human health risk

Due to urbanization and industrialization, there has been an increase in solid waste generation and has become a global concern and leakage of leachate from landfills contaminate the soil and groundwater and hence can have a severe impact on human health. The present study aimed to determine the composition of toxic metals (Cr, Mn, Cu, As) and heavy metals (Cd, Ba, Hg, Pb) in soil and water by an inductively coupled plasma optical emission spectrometer (ICP-OES). To ensure accuracy during the analysis of Cr, Mn, Cu, As, Cd, Ba, Hg, and Pb in real samples, certified reference material (CRM, SRM 2709a) of San Joaquin soil and water (SRM 1640a) were analyzed and results were presented in terms of % recovery studies. The mean concentration of all the metals in soil and water did not exceed the limit set by the European Community (EU), WHO, and US EPA except Cu where the permissible limit defined by the EU is 50-140 mg/kg in soil. The soil is uncontaminated to moderately contaminated with respect to all metals except the Cu and Pb. Among the average daily dose (ADD) of soil, ADDing and ADDinh for children had the maximum dose for all metals than adults while ADDderm was higher in adults. Hazard quotient (HQ) trend in both adults and children was found in order HQing > HQderm > HQinh of soil for all metals except Ba which followed HQing > HQinh > HQderm. Hazard index (HI) values of soil for Cr and Pb in children were 7 and 7.5 times higher than adults respectively. Lifetime cancer risk (LCR) value for Cr by different exposure pathways of soil was 5.361 × 10-4 for children which are at the lower borderline of risk for cancer.

Zinc, Zinc Transporters, and Cadmium Cytotoxicity in a Cell Culture Model of Human Urothelium

We explored the potential role of zinc (Zn) and zinc transporters in protection against cytotoxicity of cadmium (Cd) in a cell culture model of human urothelium, named UROtsa. We used real-time qRT-PCR to quantify transcript levels of 19 Zn transporters of the Zrt-/Irt-like protein (ZIP) and ZnT gene families that were expressed in UROtsa cells and were altered by Cd exposure. Cd as low as 0.1 µM induced expression of ZnT1, known to mediate efflux of Zn and Cd. Loss of cell viability by 57% was seen 24 h after exposure to 2.5 µM Cd. Exposure to 2.5 µM Cd together with 10–50 µM Zn prevented loss of cell viability by 66%. Pretreatment of the UROtsa cells with an inhibitor of glutathione biosynthesis (buthionine sulfoximine) diminished ZnT1 induction by Cd with a resultant increase in sensitivity to Cd cytotoxicity. Conversely, pretreatment of UROtsa cells with an inhibitor of DNA methylation, 5-aza-2’-deoxycytidine (aza-dC) did not change the extent of ZnT1 induction by Cd. The induced expression of ZnT1 that remained impervious in cells treated with aza-dC coincided with resistance to Cd cytotoxicity. Therefore, expression of ZnT1 efflux transporter and Cd toxicity in UROtsa cells could be modulated, in part, by DNA methylation and glutathione biosynthesis. Induced expression of ZnT1 may be a viable mechanistic approach to mitigating cytotoxicity of Cd.

The role of autophagy in metal-induced urogenital carcinogenesis

Environmental and/or occupational exposure to metals such as Arsenic (As), Cadmium (Cd), and Chromium (Cr) have been shown to induce carcinogenesis in various organs, including the urogenital system. However, the mechanisms responsible for metal-induced carcinogenesis remain elusive. We and others have shown that metals are potent inducers of autophagy, which has been suggested to be an adaptive stress response to allow metal-exposed cells to survive in hostile environments. Albeit few, recent experimental studies have shown that As and Cd promote tumorigenesis via autophagy and that inhibition of autophagic signaling suppressed metal-induced carcinogenesis. In light of the newly emerging role of autophagic involvement in metal-induced carcinogenesis, the present review focuses explicitly on the mechanistic role of autophagy and potential signaling pathways involved in As-, Cd-, and Cr-induced urogenital carcinogenesis.

Developmental toxicity of cadmium in infants and children: a review

Several millions of people are exposed to cadmium worldwide due to natural and anthropogenic activities that led to their widespread distribution in the environment and have shown potential adverse effects on the kidneys, liver, heart and nervous system. Recently human and animal-based studies have been shown that In utero and early life exposure to cadmium can have serious health issues that are related to the risk of developmental disabilities and other outcomes in adulthood. Since, cadmium crosses the placental barrier and reaches easily to the fetus, even moderate or high-level exposure of this metal during pregnancy could be of serious health consequences which might be reflected either in the children’s early or later stages of life. Mortality from various diseases including cancer, cardiovascular, respiratory, kidney and neurological problems, correlation with In utero or early life exposure to cadmium has been found in epidemiological studies. Animal studies with strong evidence of various diseases mostly support for the human studies, as well as suggested a myriad mechanism by which cadmium can interfere with human health and development. More studies are needed to establish the mechanism of cadmium-induced toxicity with environmentally relevant doses in childhood and later life. In this review, we provide a comprehensive examination of the literature addressing potential long- term health issues with In utero and early life exposure to cadmium, as well as correlating with human and animal exposure studies.

Serum and Whole Blood Cu and Zn Status in Predicting Mortality in Lung Cancer Patients

Alterations in circulating Cu and Zn are negative predictors of survival in neoplastic patients and are known during lung cancer. However, no data on predicting mortality of lung cancer patients based on the level of these elements in the blood have been presented to date. The aims of this prospective cohort study were as follows: (i) To evaluate the disturbances in serum and whole blood Cu and Zn, (ii) to assess the relationships between serum and whole blood Cu and Zn status and clinical, sociodemographic, and nutritional data, and (iii) to investigate the association of Cu and Zn status with all-cause mortality in lung cancer. Naïve-treatment lung cancer patients (n = 167) were characterized in terms of sociodemographic, clinical, and anthropometric data and dietary intake and compared with sex-matched control subjects (n = 48). Whole blood and serum Cu and Zn status was determined by atomic absorption spectrometry. Cox proportional hazards models adjusted for multiple confounders/mediators were used to estimate the association between all-cause death and Cu and Zn status. Sex, cardiovascular disease, chronic obstructive pulmonary disease, clinical stage, and hemoglobin, platelet, and glucose concentrations significantly differentiated Cu and Zn status. All-cause mortality in lung cancer patients was positively associated with serum Cu levels, Cu:Zn ratio, and whole blood Zn levels. However, an advanced clinical stage of disease was the strongest predictor of all-cause mortality. Circulatory status of Cu and Zn might be included in routine clinical characteristics of patients with lung cancer patients as additional prognostic variables, but only after further more detail studies.

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.

Association between Urinary Cadmium to Zinc Intake Ratio with Adult Mortality in a Follow-Up Study of NHANES 1988-1994 and 1999-2004

Cadmium (Cd) is a toxic heavy metal associated with increased mortality, but the effect of zinc (Zn) intake on the association between Cd and mortality is unknown. The objective of this study was to examine the association of urinary Cd to Zn intake ratio (Cd/Zn ratio) and mortality risk. In total, 15642 US adults in NHANES 1988-1994 and 1999-2004 were followed until 2011 (15-year mean follow-up). Of the 5367 total deaths, 1194 were attributed to cancer and 1677 were attributed to CVD. After adjustment for potential confounders, positive associations were observed between urinary Cd and all-cause mortality (HR for highest vs. lowest quartile: 1.38; 95% CI: 1.14-1.68) and cancer mortality (HR: 1.54; CI: 1.05-2.27). Urinary Cd was positively associated with cancer mortality among the lowest Zn consumers, and the association diminished among the highest Zn consumers. Positive relationships were observed between the Cd/Zn ratio and all-cause mortality (HR: 1.54; CI: 1.23-1.93), cancer mortality (HR: 1.65; CI: 1.11-2.47) and CVD mortality (HR: 1.49; CI: 1.18-1.88). In conclusion, these findings indicate that Zn intake may modify the association between Cd and mortality. Furthermore, the Cd/Zn ratio, which was positively associated with mortality from all causes, cancer, and CVD, may be an important predictor of mortality.

Concentrations, Distribution, Sources and Ecological Risk Assessment of Trace Elements in Soils from Wuhan, Central China

This study aimed to determine the concentration levels, potential sources and ecological risks of eleven trace elements, namely Cr, Fe, Co, Ni, Cu, As, Sb, Cd, Zn, Hg and Pb, in the soil from Huangpi district, Wuhan, Central China. Soil samples were collected from eighteen sites at soil depths of 1–10 and 10–20 cm and analyzed using Inductively Coupled Plasma-Mass Spectrometer ICP-MS (Thermo X SERIES 2, Scientific and Innovative Technology Co. Ltd., Beijing, China). The recorded mean concentration of the elements were in a decreasing order of Fe > Co > Cr > Ni > Pb > Cu > As > Cd > Sb > Zn > Hg. The mean concentration of trace elements, soil pH and total organic carbon (TOC) were higher at a soil depth of 1–10 cm. The obtained mean concentration of Cr, Co, As, Cd, Ni, Cu, Hg and Pb were above the soil background values of Wuhan and Hubei Province. The mean concentration values of Co, Ni and Cd, exceeded the recommended FAO (Food and Agriculture Organization)/ISRIC (International Soil Reference and Information Centre) (2004) and WHO/FAO (2001) values. Pearson’s correlation analysis illustrated that there was a strong and significant correlation between trace elements, whereas, a weak positive and negative correlation between elements and soil properties (pH and TOC). The principal component analysis (PCA) and cluster analysis (CA) result indicated that the concentration of trace elements in Huangpi soil were originated from anthropogenic sources. Potential ecological risk index (RI) of this study revealed that there is a high ecological risk of trace elements in the soil. Enrichment factor (EF) and geo-accumulation index (I_geo) of trace elements for this study indicated that the study area is strongly contaminated with Cd and Co. Generally, the finding of this research showed that Huangpi soil is contaminated.

Zinc supplementation can reduce accumulation of cadmium in aged metallothionein transgenic mice

Epidemiologic studies suggest that exposure to Cd is related to a multitude of age-related diseases. There is evidence that Cd toxicity emerges from an interference with Zn metabolism as they compete for the same binding sites of ligands. The most responsive proteins to Cd exposure are the metal-binding proteins termed metallothioneins (MTs), which display a much greater affinity for Cd than for Zn. Most studies have considered the effect of Zn on the accumulation of exogenous Cd and tissue damage, whereas observational studies have addressed the association between Zn intake and Cd levels in body fluids. However, it has not been addressed whether supplemental Zn can lower Cd levels in organs of healthy aged animals without affecting Cu stores, a question more pertinent to human aging. We therefore aimed to investigate the effect of Zn supplementation on Cd levels in liver and kidney of aged MT transgenic mice (MT1-tg) overexpressing MT1 at levels more comparable to those observed in humans than non-transgenic mice. We found a >30% reduction of kidney and liver Cd levels in Zn supplemented MT1-tg mice compared to non-supplemented controls, independently of the dose of Zn, without a significant reduction of Cu. Our data support the idea of a causal and inverse relationship between Zn intake and Cd content in organs of aged MT1-tg mice as suggested by observational studies in humans. Our work provides the rationale for interventional studies to address the effects of Zn supplementation on Cd burden in elderly people.

Nutraceuticals in prostate cancer therapeutic strategies and their neo-adjuvant use in diverse populations

Prostate cancer (PCa) is the most frequently diagnosed malignancy and second leading cause of cancer mortality in American males. Notably, men of African descent in the United States and Caribbean have the highest PCa mortality rates compared to men with European ancestry. Although current therapeutics are quite potent and effective, disease resistance, progression to metastasis, therapy-associated toxicities and efficacy-related issues in diverse populations develop over time. Thus, non-toxic and efficacious therapeutic strategies are needed to address these major obstacles for the clinical treatment and management of PCa. In this regard, preclinical and population-based efficacy studies have shown the potential of natural non-toxic nutraceuticals as potent anti-PCa agents. Accordingly, the implementation of nutraceutical intervention and genetic testing in diverse populations might aid in the development and design of precision medicine strategies to reduce the burden of chemotherapy-associated toxicities, suppress disease resistance, and treat both localized and advanced PCa. Consequently, additional large-scale and inclusive clinical studies are required to fully assess efficacy and therapeutic limitations of these agents in PCa. This review discusses the most current clinical research on selected nutraceutical agents and their efficacy in the context of clinico-pathological outcomes and disease susceptibility in diverse PCa clinical and epidemiological studies.

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.

Blood mercury, lead and cadmium levels and determinants of exposure among newcomer South and East Asian women of reproductive age living in Vancouver, Canada

BACKGROUND

Biomarkers of the reproductive and neuro-developmental toxicants mercury (Hg), lead (Pb) and cadmium (Cd) have been found at higher concentrations in women born outside Canada than in Canadian-born women. We measured blood Hg, Pb and Cd in women ages 19 to 45years living in greater Vancouver (Canada) within five years of their arrival from South Asia (India) or East Asia (mainland China, Hong Kong and Taiwan) and related their biomarker concentration levels with exposures and behaviors since their coming to Canada.

METHODS

Participants were recruited through advertisements in relevant ethnic media, locations and groups. Concentrations of blood Hg, Pb and Cd were analyzed by inductively coupled plasma-mass spectrometry (ICP-Q-MS) and compared with population values. Biomarker concentrations were regressed against exposures and behaviors assessed by culturally-relevant questionnaire.

RESULTS

The study recruited 53 South and 111 East Asian women. Median (95th percentile) blood Pb in South Asians was 1.15 (2.71) μg/dL compared with 1.01 (1.81) μg/dL in East Asians. On the other hand, blood Hg at 2.5 (7.3) μg/L was higher in East Asians compared to 0.20 (0.83) μg/L in South Asians. Blood Cd was also higher in the East Asian group: East 0.53 (1.1) μg/L; South 0.27 (0.82) μg/L. Higher blood Hg was associated with seafood consumption, dental amalgams and traditional remedies; blood Pb with home renovations, sucking on metal jewelry, and cosmetics. Blood Pb and Cd concentrations were inversely associated with dairy consumption.

CONCLUSIONS

Asian women recently arrived in Vancouver had higher blood Hg, Pb and Cd concentrations than same-age Canadian women measured in a national survey. Among South Asian newcomer women of reproductive age, exposure to Cd may continue after arrival. Local exposures to Hg occur through seafood and potentially through ingestion of imported traditional remedies.

Chronic exposure to low-level cadmium induced zinc-copper dysregulation

BACKGROUND AND OBJECTIVES

Exposure to cadmium (Cd) has been associated with aberrant zinc and copper homeostasis. This study investigated if Cd exposure impairs renal reabsorption of metals.

METHODS

Renal tubular reabsorption of metals were calculated from urine to serum metal ratios and analyzed for an independent association with Cd exposure levels, using data from 100 men and 100 women, aged 16-60 years.

RESULTS

The smoking prevalence was 30% in men and 0% in women. The male and female means (SD) for urine Cd were 0.54 (0.43) and 0.62 (0.43) μg/g creatinine. The mean (SD) for fractional zinc reabsorption was 77.2 (23) % in men and 87.7 (13.3) % in women, while the copper reabsorption was 100% in both men and women. Lower zinc reabsorption levels were associated with higher Cd exposure (P<0.001), higher serum copper to zinc ratios (P=0.007) and higher tubular impairment levels (P=0.024). Reduced zinc reabsorption was particularly severe in smokers as those with high Cd exposure had 44.9% and 37.2% (P<0.001) lower zinc reabsorption than those with low and moderate exposures. The mean zinc reabsorption in male non-smokers with high Cd exposure was 25.8% (P<0.001) and 18.2% (P=0.003) lower than those with low and moderate exposures, while the corresponding figure for female non-smokers was 17% (P<0.001), and 12.8% (P=0.013), respectively.

CONCLUSIONS

This is the first report demonstrating Cd-dose dependent reduction in renal zinc reabsorption and high serum copper to zinc ratios.

Assessment of soil heavy metals for eco-environment and human health in a rapidly urbanization area of the upper Yangtze Basin

Soil pollution with heavy metals (HMs) has been attracting more and more interests, however, assessment of eco-environmental and human risks particularly in a rapidly urbanization area (the upper Yangtze) remains limited. Multiple modern indices were firstly performed for complete risk assessment of eco-environment and human health based on a high-spatial-resolution sampling. Averages of HMs were far below grade II threshold level of the Chinese Environmental Quality standards for soils, whereas Cd, As and Hg considerably exceeded the local background values. EF suggested overall moderate enrichments of Cd and Se, resulting in soils uncontaminated to moderately contaminated with them. Potential ecological risk index showed significant differences among Counties that were characterized by moderate risk. However, several sites were moderately to heavily contaminated with As, Cd and Hg by Igeo, resulting in that these sites were categorized as “considerable risk”, or “high risk”. Moreover, children were more susceptible to the potential health risk irrespective of the carcinogenic or non – carcinogenic risk. There were no significant carcinogenic and non – carcinogenic risks for adults, children however showed significant non – carcinogenic effect. Our first assessment provided important information for policy making to reduce the potential effects of soil contamination on human and eco-environment.

Environmental exposure to cadmium-a risk for health of the general population in industrialized countries and preventive strategies

Cadmium (Cd) is a heavy metal belonging to the group of the main chemical pollutants of the natural and occupational environment in economically developed countries. The forecasts indicate that contamination of the environment with this toxic metal, and thus the exposure of the general population, will increase. Food (particularly plant products) is the main source of the general population exposure to this element. Moreover, an important, and often the main, source of intoxication with Cd is habitual tobacco smoking. Recent epidemiological studies have provided numerous evidence that even low-level environmental exposure to this toxic metal, nowadays occurring in numerous economically developed countries, creates a risk for health of the general population. The low-level lifetime exposure to this metal may lead to the damage to the kidneys, liver, skeletal system, and cardiovascular system, as well as to the deterioration of the sight and hearing. Moreover, it has been suggested that environmental exposure to this xenobiotic may contribute to the development of cancer of the lung, breast, prostate, pancreas, urinary bladder, and nasopharynx. Taking the above into account, the aim of this review article is to draw more attention to Cd as an environmental risk factor for the health of the general population and the need to undertake preventive actions allowing to reduce the risk of health damage due to a lifetime exposure to this toxic metal.

Recent views of heavy metals as possible risk factors and potential preventive and therapeutic agents in prostate cancer

Prostate cancer is the most common cancer in men in many industrialized countries. A role for androgens in prostate tumor progression is well recognized, while estrogens may cooperate with androgens in prostate carcinogenesis. The incidence of prostate cancer is highly variable in the different countries, suggesting an important role of environmental factors. Heavy metals are common environmental contaminants and some of them are confirmed or suspected human carcinogens. Some metals are endowed with estrogenic and/or androgenic activities and may play a role as cancer risk factors through this mechanism. Moreover, prostate cancer may present alterations in the intracellular balance of trace metals, such as zinc and copper, which are involved in several regulatory proteins. Herein, we review the possible role of environmental heavy metals and of metal-dyshomeostasis in prostate cancer development and promotion as well as the potential use of some metals in the prevention and therapy of prostate cancer.

Mineral Dietary Supplement To Decrease Cadmium Relative Bioavailability in Rice Based on a Mouse Bioassay

To determine the effectiveness of mineral dietary supplements to modulate cadmium (Cd) exposure, an in vivo mouse bioassay was conducted to determine Cd relative bioavailability (Cd-RBA) in Cd-contaminated rice (0.80 mg Cd kg^-1) with and without Zn, Fe, or Ca supplements as nitrate or chloride salts. Without mineral supplements, Cd-RBA was 43 ± 5.3% based on average Cd accumulation in the liver plus kidneys as the end point. Among Ca(NO₃)₂, Zn(NO₃)₂, and Fe(NO₃)₂ supplements, 150-5000 mg kg^-1 Ca was the most effective in reducing rice Cd-RBA by 31-80% to 8.5-29%, while 30-200 mg kg^-1 Zn supplements was ineffective, with Cd-RBA being 33-57%. Low Fe at <40 mg kg^-1 had little impact on rice Cd-RBA (39-47%), while high Fe at 80-200 mg kg^-1 decreased Cd-RBA by 37% to 26-27%. The ineffectiveness of Zn supplements in reducing Cd-RBA was probably due to coinciding 8.3- and 3.1-fold increases in Zn accumulation in mouse kidneys and liver with Zn supplements, while Ca and Fe supplements led to much-smaller increases in Ca and Fe accumulation in mouse tissues (1.3-1.6 fold). In addition, compared to Ca(NO₃)₂ supplements, Cd-RBA values determined with CaCl₂ supplements were significantly higher (25-67% versus 8.5-29%), suggesting that chloride enhanced Cd-RBA. Results of this study have important implications for developing effective dietary strategies to reduce dietary Cd exposure and the associated health risks in humans.

Current health risk assessment practice for dietary cadmium: Data from different countries

Cadmium (Cd) is an environmental toxicant with high rates of soil-to-plant transference. This makes exposure to Cd through the food-chain contamination a public health concern. Cd accumulates in kidneys, and the most frequently reported adverse effect of long-term Cd intake is injury to kidneys. The FAO/WHO Joint Expert Committee on Food Additives established a tolerable dietary intake level and a threshold to safeguard population health. The FAO/WHO tolerable intake was set at 25 μg per kg body weight per month (58 μg per day for a 70-kg person) with urinary Cd threshold at 5.24 μg/g creatinine. Worldwide population data indicate that urinary Cd excretion reflects cumulative Cd exposure or body burden more accurately than estimated Cd intake, derived from total diet study (TDS). For the adult population, TDS estimated Cd intake of 8-25 μg/day, while urinary Cd levels suggest higher intake levels (>30 μg/day). These Cd intake estimates are below the FAO/WHO intake guideline, but they exceed the levels that are associated with distinct pathologies in many organ systems. A wide diversity of Cd toxicity targets and Cd toxicity levels argue for a more restrictive dietary Cd intake guideline and the measures that minimize Cd levels in foodstuffs.

Factors affecting the variability in the observed levels of cadmium in blood and urine among former and current smokers aged 20-64 and ≥ 65years

Data from National Health and Nutrition Examination Survey for 1999-2012 were used to evaluate factors that affect observed levels of blood cadmium (BCd) and urine cadmium (UCd) among former and current smokers aged 20-64 and ≥65 years. Adjusted levels (AGM) for BCd and UCd were higher among females as compared to males. The order of AGM for BCd by race/ethnicity for 20-64 years old was non-Hispanic white (NHW) < non-Hispanic black (NHB) and NHW > NHB for ≥65 years old. The order of AGMs for UCd for 20-64-year-old current smokers was NHW > NHB and NHW > NHB for former smokers. For 20-64-year-old current smokers, exposure to environmental tobacco smoke at home was associated with higher levels of BCd. Levels of both UCd and BCd increased with age, but the rate of increase was as much as seven times higher among ≥65 years old than 20-64 years old. For current smokers, the number of cigarettes smoked inside home was positively associated with the levels of BCd. For current smokers aged 20-64 years, the number of cigarettes smoked inside home was positively associated with the levels of UCd (p < 0.01), and the number of cigarettes smoked every day on the days they were smoked was also positively associated with the levels of UCd (p < 0.01). Among former smokers, levels of both UCd and BCd were positively associated (p < 0.1) with the number of cigarettes smoked per day at the time of quitting smoking and negatively associated with the time since smoking was quitted (p < 0.01).

Health Risk Assessment of Dietary Cadmium Intake: Do Current Guidelines Indicate How Much is Safe?

BACKGROUND

Cadmium (Cd), a food-chain contaminant, is a significant health hazard. The kidney is one of the primary sites of injury after chronic Cd exposure. Kidney-based risk assessment establishes the urinary Cd threshold at 5.24 μg/g creatinine, and tolerable dietary intake of Cd at 62 μg/day per 70-kg person. However, cohort studies show that dietary Cd intake below a threshold limit and that tolerable levels may increase the risk of death from cancer, cardiovascular disease, and Alzheimer's disease.

OBJECTIVE

We evaluated if the current tolerable dietary Cd intake guideline and urinary Cd threshold limit provide sufficient health protection.

DISCUSSION

Staple foods constitute 40-60% of total dietary Cd intake by average consumers. Diets high in shellfish, crustaceans, mollusks, spinach, and offal add to dietary Cd sources. Modeling studies predict the current tolerable dietary intake corresponding to urinary Cd of 0.70-1.85 μg/g creatinine in men and 0.95-3.07 μg/g creatinine in women. Urinary Cd levels of < 1 μg/g creatinine were associated with progressive kidney dysfunction and peripheral vascular disease. A urinary Cd of 0.37 μg/g creatinine was associated with breast cancer, whereas dietary Cd of 16-31.5 μg/day was associated with 25-94% increase in risk of estrogen receptor-positive breast cancer.

CONCLUSION

Modeling shows that dietary intake levels for Cd exceed the levels associated with kidney damage and many other adverse outcomes. Thus, the threshold level of urinary Cd should be re-evaluated. A more restrictive dietary intake guideline would afford enhanced health protection from this pervasive toxic metal. Citation: Satarug S, Vesey DA, Gobe GC. 2017. Health risk assessment of dietary cadmium intake: do current guidelines indicate how much is safe? Environ Health Perspect 125:284-288; http://dx.doi.org/10.1289/EHP108.

Zinc Intake and Risk of Prostate Cancer: Case-Control Study and Meta-Analysis

Zinc is an essential dietary element that has been implicated in the pathogenesis of prostate cancer, a cancer that disproportionately affects men of African descent. Studies assessing the association of zinc intake and prostate cancer have yielded inconsistent results. Furthermore, very little is known about the relationship between zinc intake and prostate cancer among African Americans. We examined the association between self-reported zinc intake and prostate cancer in a hospital-based case-control study of African Americans. We then compared our results with previous studies by performing a meta-analysis to summarize the evidence regarding the association between zinc and prostate cancer. Newly diagnosed African American men with histologically confirmed prostate cancer (n = 127) and controls (n = 81) were recruited from an urban academic urology clinic in Washington, DC. Controls had higher zinc intake, with a mean of 14 mg/day versus 11 mg/day for cases. We observed a non-significant, non-linear increase in prostate cancer when comparing tertiles of zinc intake (OR <6.5 vs 6.5-12.5mg/day 1.8, 95% CI: 0.6,5.6; OR <6.5 vs >12.5mg/day 1.3, 95% CI: 0.2,6.5). The pooled estimate from 17 studies (including 3 cohorts, 2 nested case-control, 11 case-control studies, and 1 randomized clinical trial, with a total of 111,199 participants and 11,689 cases of prostate cancer) was 1.07hi vs lo 95% CI: 0.98-1.16. Using a dose-response meta-analysis, we observed a non-linear trend in the relationship between zinc intake and prostate cancer (p for nonlinearity = 0.0022). This is the first study to examine the relationship between zinc intake in black men and risk of prostate cancer and systematically evaluate available epidemiologic evidence about the magnitude of the relationship between zinc intake and prostate cancer. Despite of the lower intake of zinc by prostate cancer patients, our meta-analysis indicated that there is no evidence for an association between zinc intake and prostate cancer.

Urinary cadmium and estimated dietary cadmium in the Women's Health Initiative

Cadmium, a heavy metal dispersed in the environment as a result of industrial and agricultural applications, has been implicated in several human diseases including renal disease, cancers, and compromised bone health. In the general population, the predominant sources of cadmium exposure are tobacco and diet. Urinary cadmium (uCd) reflects long-term exposure and has been frequently used to assess cadmium exposure in epidemiological studies; estimated dietary intake of cadmium (dCd) has also been used in several studies. The validity of dCd in comparison with uCd is unclear. This study aimed to compare dCd, estimated from food frequency questionnaires, to uCd measured in spot urine samples from 1,002 participants of the Women's Health Initiative. Using linear regression, we found that dCd was not statistically significantly associated with uCd (β=0.006, P-value=0.14). When stratified by smoking status, dCd was not significantly associated with uCd both in never smokers (β=0.006, P-value=0.09) and in ever smokers (β=0.003, P-value=0.67). Our results suggest that because of the lack of association between estimated dCd and measured uCd, dietary estimation of cadmium exposure should be used with caution in epidemiologic studies.

Heavy Metal Accumulation is Associated with Molecular and Pathological Perturbations in Liver of Variola louti from the Jeddah Coast of Red Sea

Large amounts of waste water are discharged daily from the Jeddah Metropolitan Area into the Red Sea. Sewage draining into the Red Sea causes widespread chemical pollution that is toxic to aquatic ecosystems. The objective of this study was to investigate the extent of pollution and assess the presence of heavy metals in fish tissue and study their association with biological and biochemical alterations. The average concentrations of heavy metals found in hepatic tissues of Variola louti fish from the polluted area, namely Cd, Cr, Cu, Fe and Zn, were 1.74, 9.69, 47.48, 4020.01 and 229.47 µg/g liver, respectively, that were significantly higher than that of samples taken from reference area (0.24, 1.98, 20.12, 721.93, 129.21 µg/g liver, respectively). The fold change of heavy metals in fish from the polluted area with respect of that of the reference area followed the order Cd > Fe > Cr > Cu > Zn. Analysis of nuclear DNA revealed that hepatic tissues of fish samples from the polluted area showed a significant increase in apoptotic cells as detected by flow cytometry and formation DNA-ladder. In addition, hepatic sections from polluted area fishes showed more fibrotic changes and collagen deposition by hematoxylin-eosin staining and Masson's trichrome staining, respectively, compared to samples taken from the reference area. Moreover, the electrophoretic patterns of proteins of liver of fishes caught at the polluted area showed different patterns of proteins from that of the reference with bands at 42, 130 and 140 kDa, which is in a good agreement with the molecular weight of collagen type III. In conclusion, there were significant changes in the tissues of fishes in the polluted area at the cellular and the molecular levels that may be associated with an accumulation of heavy metals. Assessment of fishes as a sensitive biomonitor for the pollution of surface waters that may affect general health of human and wild life is conceivable.

Association Between Cd Exposure and Risk of Prostate Cancer: A PRISMA-Compliant Systematic Review and Meta-Analysis

Several observational studies on the association between Cd exposure and risk of prostate cancer have yielded inconsistent results. To address this issue, we conducted a meta-analysis to evaluate the correlation between Cd exposure and risk of prostate cancer.Relevant studies in PubMed and Embase databases were retrieved until October 2015. We compared the highest and lowest meta-analyses to quantitatively evaluate the relationship between Cd exposure and risk of prostate cancer. Summary estimates were obtained using a random-effects model.In the general population, high Cd exposure was not associated with increased prostate cancer (OR 1.21; 95% CI 0.91-1.64), whereas the combined standardized mortality ratio of the association between Cd exposure and risk of prostate cancer was 1.66 (95% CI 1.10-2.50) in populations exposed to occupational Cd. In addition, high D-Cd intake (OR 1.07; 95% CI 0.96-1.20) and U-Cd concentration (OR 0.86; 95% CI 0.48-1.55) among the general population was not related to the increased risk of prostate cancer. In the dose analysis, the summary relative risk was 1.07 (95% CI 0.73-1.57) for each 0.5 μg/g creatinine increase in U-Cd and 1.02 (95% CI 0.99-1.06) for each 10 μg/day increase of dietary Cd intake. However, compared with nonoccupational exposure, high occupational Cd exposure may be associated with the increased risk of prostate cancer.This meta-analysis suggests high Cd exposure as a risk factor for prostate cancer in occupational rather than nonoccupational populations. However, these results should be carefully interpreted because of the significant heterogeneity among studies. Additional large-scale and high-quality prospective studies are needed to confirm the association between Cd exposure and risk of prostate cancer.

Zinc Intake Is Associated with Lower Cadmium Burden in U.S. Adults

BACKGROUND

Cadmium is a toxic transition metal whose absorption and accumulation might depend on zinc intake.

OBJECTIVE

We sought to determine whether zinc intake and serum zinc would be inversely associated with cadmium exposure.

METHODS

This study used data from NHANES 2003-2012, from which there were 6678 and 6488 participants with urinary and blood cadmium data, respectively, and 1195 participants with serum zinc data. Mean blood and urinary cadmium were reported by quintiles of zinc intake and by the dose and duration of zinc supplement use. The associations between zinc intake from diet and supplements, serum zinc, and blood and urinary cadmium were determined using multiple regression. Analyses were adjusted for age, body mass index, race/ethnicity, gender, income-to-poverty ratio, education, smoking status, and mean intakes of energy, calcium, and iron.

RESULTS

Urinary cadmium concentrations were 0.04 μg/g creatinine lower among participants in the highest compared with lowest quintile of total zinc intake (P-trend = 0.0041). Zinc supplement dose and duration were inversely associated with blood cadmium (P = 0.0372) and serum zinc (P-trend = 0.0017), respectively. In adjusted regression models, a 10% increase in total zinc intake corresponded to a predicted decrease in blood cadmium of 0.42% (95% CI: -0.79%, -0.06%; P = 0.0260) and in urinary cadmium of 0.42% (95% CI: -0.81%, -0.04%; P = 0.0340). A 10% increase in serum zinc was associated with a predicted 1.99% (95% CI: -3.17%, -0.81%; P = 0.0012) decrease in blood cadmium and a predicted 4.09% (95% CI: 2.14%, 6.04%, P = 0.0001) increase in urinary cadmium.

CONCLUSIONS

Dietary and serum zinc in US adults are associated with cadmium exposure, presumably by influencing the absorption and accumulation of cadmium. Whether the degree of reduction in cadmium exposure from greater zinc intake and status is causal or relevant from a public health perspective needs further investigation.

Cadmium exposure and risk of pancreatic cancer: a meta-analysis of prospective cohort studies and case-control studies among individuals without occupational exposure history

Pancreatic cancer is one of the most deadly types of cancer for both genders. Classified as a human carcinogen, cadmium has been related to diverse cancers. However, the association between cadmium exposure and the risk of pancreatic cancer is still unclear. We quantitatively reviewed the observational studies on the association of cadmium exposure with pancreatic cancer risk among individuals without occupational exposure history published through July 2014 in PubMed by using a fixed-effect model. Four prospective cohort studies (112,934 participants with 335 events) and two case-control studies (177 cases and 539 controls) were identified. The summarized relative risk (RR) with a 95% confidence interval (CI) was 2.05 (95% CI = 1.58-2.66), comparing the highest to the lowest category of cadmium exposure. This positive association persisted in men (RR = 1.78, 95% CI = 1.04-3.05) but not in women (RR = 1.02, 95% CI = 0.63-1.65). Further research is needed to provide more solid evidence on the association of cadmium exposure with pancreatic cancer risk and to elucidate the underlying biological mechanism of the potential gender difference.

Toxic and essential elements in Nigerian rice and estimation of dietary intake through rice consumption

In this study, levels and estimated daily intake (EDI) of two toxic elements, Cd and Pb, and eight essential elements: Ca, P, Zn, Mn, Co, Cu, Se and Mo, were determined in Nigerian rice samples. The mean levels of Cd, Pb and Co were 5.43±0.88, 38.66±5.42, 25.8±3.18 ng/g. The mean levels of Ca, P, Zn, Mn, Cu, Se and Mo were 71.5±7.31, 951±52.0, 10.2±0.63, 8.5±0.47, 3.07±0.18, 40.1±9.2 and 0.39±0.05 µg/g, respectively. The percentage contribution to the reference values for each element was 0.54, 7.71, 0.38, 9.51, 8.97, 31.3, 30.7, 5.1 and 60.7% for Cd, Pb, Ca, P, Zn, Mn, Cu, Se and Mo, respectively. The elemental nutrient levels in Nigerian rice samples are comparable to those obtained from other regions and their consumption does not pose any serious health risk to consumers.

Cadmium induces the activation of cell wall integrity pathway in budding yeast

MAP kinases are important signaling molecules regulating cell survival, proliferation and differentiation, and can be activated by cadmium stress. In this study, we demonstrate that cadmium induces phosphorylation of the yeast cell wall integrity (CWI) pathway_MAP kinase Slt2, and this cadmium-induced CWI activation is mediated by the cell surface sensor Mid2 through the GEF Rom1, the central regulator Rho1 and Bck1. Nevertheless, cadmium stress does not affect the subcellular localization of Slt2 proteins. In addition, this cadmium-induced CWI activation is independent on the calcium/calcineurin signaling and the high osmolarity glycerol (HOG) signaling pathways in yeast cells. Furthermore, we tested the cadmium sensitivity of 42 paired double-gene deletion mutants between six CWI components and seven components of the HOG pathway. Our results indicate that the CWI pathway is epistatic to the HOG pathway in cadmium sensitivity. However, gene deletion mutations for the Swi4/Swi6 transcription factor complex show synergistic effects with mutations of HOG components in cadmium sensitivity.

Association of total cancer and lung cancer with environmental exposure to cadmium: the meta-analytical evidence

BACKGROUND

Recent studies are indicative of substantial progress in understanding the dose-response relation between the incidence of total and lung cancer and environmental cadmium exposure. We conducted a meta-analysis of population studies that examined the risk of cancer in relation to lifetime exposure to cadmium.

METHODS

We searched MEDLINE, Web of Science, and relevant reviews until August 2014 for studies on the association between cancer risk and cadmium exposure. Eligible studies had to include an estimate of lifetime exposure to cadmium as reflected by the urinary cadmium concentration and adjustment of the cancer risk at least for age and smoking. We pooled relative risk across the studies estimates for cancer and lung cancer using variance-weighted random-effect models and expressed association sizes for a twofold increase in urinary cadmium, thereby respecting the continuous nature of the association.

RESULTS

The meta-analysis included 20,459 participants from three prospective population studies. The average urinary cadmium concentration across populations ranged from 0.25 to 0.93 µg/g creatinine. The relative risk of total cancer, associated with a doubling of the urinary cadmium concentration, ranged across the different studies from 1.18 to 1.31, and the pooled relative risk was 1.22 (95% CI 1.13-1.31; p < 0.0001). For lung cancer, the relative risk ranged from 1.21 to 1.70 for a doubling of the urinary cadmium concentration, while the pooled relative risk amounted to 1.68 (1.47-1.92; p < 0.0001). Excluding one study at the time did not move the pooled estimates outside the confidence interval of the overall estimate for all studies combined.

CONCLUSION

The epidemiological evidence of the last decade consistently identifies low-level environmental exposure to cadmium as a risk factor for total cancer and lung cancer.