Urinary cadmium levels and tobacco smoke exposure in women age 20-69 years in the United States

Association of environmental tobacco smoke (ETS) with lead and cadmium concentrations in biological samples of children and women: systematic review and meta-analysis

OBJECTIVES

Previous literature has shown that heavy metals (HMs) in cigarette smoke have been overestimated, and second-hand smoke (SHS) has recently raised public concern. This study aimed to review the effects of passive tobacco exposure on lead (Pb) and cadmium (Cd) concentrations of children and women in different biological samples.

CONTENT

In this systematic review, two independent researchers assessed different databases/search engines including PubMed, Web of Science, Scopus, and Google Scholar using Mesh terms and Text Words. Studies between January 2000 and May 2022 were included. After quality assessment, studies with sufficient data were included in the meta-analysis. A fixed or random model was used to pool the results in a meta-analysis. Heterogeneity between the studies was assessed by using I-square and Q tests. Forest plots demonstrating the point and pooled estimates were provided.

SUMMARY

A total of 976 studies were obtained from different databases and finally 17 studies meet our criteria and were included in our systematic review. Out of 17 studies, six studies had sufficient data for analysis and were included in the meta-analysis. The results of the meta-analysis showed a significant difference in blood lead concentrations (BLC) between the children with SHS exposure and the control group (Hedges' g: 2.44, 95% CI: 1.01-3.86, p<0.05). Also, there were significant differences in hair levels of Cd (Hedges' g: 0.66, 95% CI: 0.04, 1.28, p<0.05) and Pb (Hedges' g: 0.94, 95% CI: 0.05, 1.83, p<0.05) between children with SHS exposure compared to the control group.

OUTLOOK

The results of the present meta-analysis showed that passive smokers had higher Pb and Cd concentrations than those who were not exposed to cigarette smoke.

The impact of electronic and conventional cigarettes on periodontal health-a systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis examined the effects of electronic cigarettes on periodontal health compared to conventional cigarette smoke and a non-smoking population.

MATERIALS AND METHODS

MEDLINE, Embase, Web of Science, CENTRAL, and ClinicalTrials.gov were screened for literature. Eligibility criteria included clinical studies published between 2006 and 2022 that compare e-cigarettes and conventional cigarettes on periodontal health (bleeding on probing (BoP), plaque index (PI), probing depth (PD), attachment loss (AL), marginal bone loss (MBL), tooth loss, molecular inflammation markers, salivary flow rate). Meta-regression analysis was used to examine the influence of moderator variables.

RESULTS

Sixteen studies were found to be eligible for qualitative synthesis. Individual analyses showed that cigarette smokers had significantly higher PI, PD, AL, and MBL and increased concentrations of proinflammatory mediators than e-cigarette users and non-smokers. Meta-analysis revealed a 0.33-fold lower chance for BoP in e-cigarette users compared to smokers (p = 0.03), whereby meta-regression failed to detect any effects regarding the age of users and frequency of smoking. A 0.01-fold decreased chance for positive BoP in e-cigarette users compared with non-smokers was seen (p < 0.01).

CONCLUSIONS

The current findings suggest that that e-cigarette use might be considered a healthier alternative to cigarette smoking concerning periodontal health. Even so, harmful effects of electronic nicotine delivery system (ENDS) usage on periodontal health were seen as well. However, a definitive decision on this research question remains elusive due to the absence of randomized controlled trials.

CLINICAL RELEVANCE

Electronic cigarettes, marketed as a safer alternative to traditional cigarettes, are becoming increasingly popular. Evidence on the use of electronic cigarettes as a cessation aid and its beneficial impact compared to cigarette smoke remains inconclusive, so the analysis conducted in this review addresses a recent question of high clinical relevance.

Smoking and Risk of Urolithiasis: Meta-Analysis of Observational Studies

Background

Earlier studies have warned about the effects of smoking on urolithiasis. Some studies have deemed that smoking has a promoting effect on urolithiasis, whereas others have considered that no inevitable association exists between the two. Therefore, we conducted a meta-analysis to estimate whether smoking is associated with urolithiasis risk.

Methods

To identify publications from related observational studies, we performed a search on PubMed, Web of Science, Embase, and the Cochrane Library databases from inception until October 1, 2021. According to the heterogeneity, random-effect model was used to calculate the odds ratios (ORs) and corresponding 95% confidence intervals (CIs).

Results

Five articles were included in the meta-analysis, representing data for 20,402 subjects, of which 1,758 (8.62%) had urolithiasis as defined according to the criteria. Three articles are concerned with analysis between ex-smokers and non-smokers, in which a significant difference was observed (OR = 1.73, 95% CI: 1.48–2.01). Our comparison of current smokers with non-smokers in another meta-analysis of three articles revealed no significant difference between them (OR = 1.08, 95% CI: 0.94–1.23). Finally, we separated subjects into ever-smokers and never-smokers and found a significant difference between the two groups in the analysis of three articles (OR = 1.31, 95% CI: 1.17–1.47). Sensitivity analysis confirmed the stability of the current results.

Conclusion

Combined evidence from observational studies demonstrates a significant relation between smoking and urolithiasis. The trend of elevated urolithiasis risk from smoking was found in ever-smokers vs. never-smokers.

Tobacco Smoke Exposure and Urinary Cadmium in Women from Northern Mexico

Cadmium (Cd), a carcinogenic metal also related to reproductive and cardiovascular diseases, is contained in tobacco and elevated concentrations of it in humans have been consistently associated with first-hand tobacco smoke; however, there is scarce and inconclusive evidence of the relationship between Cd and secondhand smoke (SHS) exposure. Our aim was to evaluate the association between exposure to tobacco, both active and SHS, with urinary Cd concentrations in Mexican women. In a cross-sectional analysis that included 998 women living in northern Mexico, we measured the concentration of creatinine-adjusted urinary Cd (µg-cadmium/g-creatinine) using inductively coupled plasma triple quadrupole (ICP-QQQ) in tandem mass spectrometry mode (MS/MS). We gathered tobacco smoking information through an in-person interview and formed seven groups: non-smokers without SHS exposure; non-smokers with SHS exposure; ex-smokers without SHS exposure <1 year of quitting; ex-smokers without SHS exposure ≥1 year of quitting, ex-smokers with SHS exposure <1 year of quitting; ex-smokers with SHS exposure ≥1 year of quitting and current smokers. The interview also yielded sociodemographic characteristics. We used linear multivariable regression models to estimate the association between Cd concentrations and tobacco smoke exposure. Compared to non-smokers without SHS exposure, we found higher Cd concentrations in ex-smokers with SHS exposure <1 year of quitting and current smokers (adjusted geometric means 0.51 vs. 1.01 and 0.69 µg-cadmium/g-creatinine, respectively). Our results do not support a conclusion that SHS exposure is a source of Cd body burden.

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

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

Urinary cadmium concentrations and metabolic syndrome in U.S. adults: The National Health and Nutrition Examination Survey 2001-2014

BACKGROUND

Low to moderate acute cadmium exposure has been associated with increased risk of chronic diseases, such as cardiovascular and kidney disease. Little is known about the association between urinary cadmium levels-an indicator of longer-term exposure-and metabolic syndrome (MetS).

METHODS

We analysed data from 3982 participants aged 20-<80 years of the National Health and Nutrition Examination Survey 2001-2014. Urinary cadmium levels were measured and adjusted for creatinine using spot urine samples. Cadmium levels were evaluated in quintiles (Q). MetS was defined by National Cholesterol Education Program's Adult Treatment Panel III report criteria. Prevalence odds ratios (OR) and 95% confidence intervals (CI) were calculated using multivariable logistic regression accounting for complex survey design, while adjusting for potential confounders and stratifying by sex and smoking status.

RESULTS

In the overall study population, there was a marginal inverse association between urinary cadmium and MetS (adj. OR for Q5 versus Q1: 0.7; 95% CI: 0.5-1.0). Sex stratified models were similar. When examining individual components of MetS, participants with higher levels of urinary cadmium had decreased odds of abdominal obesity (adj. OR for Q5 versus Q1 0.4; 95% CI: 0.3-0.6), but increased odds for low HDL (adj. OR for Q5 versus Q1 2.1; 95% CI: 1.4-3.1). Among current smokers, higher urinary cadmium was associated with increased odds of MetS, hypertension, and low HDL even after accounting for serum cotinine-a marker of smoking intensity.

CONCLUSIONS

Higher levels of urinary cadmium, a marker of long term exposure, were not associated with an increased risk of MetS in the overall study population. However, higher urine cadmium was associated with altered MetS components. Current smokers were the most vulnerable group, with higher long-term cadmium exposure being associated with increased risk of MetS, low HDL, and hypertension.

Association Between Chronic Exposure to Tobacco Smoke and Accumulation of Toxic Metals in Hair Among Pregnant Women

Tobacco smoke contains various toxic heavy metals that individuals are exposed to when they smoke. Despite the presence of heavy metals in tobacco smoke, the relationship between smoking and the accumulation of toxic metals in pregnant women after long-term exposure remains under discussion. We examined the association between long-term exposure to tobacco smoke and the accumulation of toxic metals in the hair of female participants. Our study recruited 252 women from the Shanxi and Hebei provinces of Northern China; these participants were self-reported non-active smokers, and had previously delivered healthy babies without birth defects. Scalp hair was collected and analyzed for nicotine and cotinine and five potentially toxic metals (specifically, silver, chromium, cadmium, mercury, and lead). Our results showed significant positive correlations between cotinine and four metals, including silver (r = 0.369, p < 0.001), cadmium (r = 0.185, p < 0.01), mercury (r = 0.161, p < 0.05), and lead (r = 0.243, p < 0.001). Significant positive correlations were also found between nicotine and three metals-specifically silver (r = 0.331, p < 0.001), cadmium (r = 0.176, p < 0.01), and lead (r = 0.316, p < 0.001). A logistic regression model showed significant associations between cotinine and potentially toxic metals including mercury, silver, and lead (with or without adjusting for potential confounders). We thus conclude that long-term passive smoking could potentially increase the exposure level of toxic metals including lead, silver, and mercury in our study, which are especially harmful for pregnant women and their unborn fetus.

Biomonitoring of trace elements in urine samples of children from a coal-mining region

Biomonitoring through urine samples is important for evaluating environmental exposure, since urine is the main form of excretion for most chemical elements. Children are considered more vulnerable to adverse environmental conditions, especially children in developing countries. This study aimed to biomonitor trace elements in urine samples in children from a coal-mining region in the extreme south of Brazil. A cross-sectional study was conducted on 96 children between 6 and 11 years of age. Socioeconomic data and urine samples were collected to estimate the concentration of iron, zinc, selenium, lead, and cadmium. The prevalence of metals above the reference values was 52.0% for Se, followed by 15.6% for Zn. The data point toward a vulnerability to adverse environmental conditions in these children. Although the concentrations of the elements did not reveal intoxication cases, biomonitoring should be carried out continuously in order to assess exposure to metals and ensure the health of the population. This article provides data that help determine natural levels of metallic elements in children, specifically in South America, which have not yet been established.

Biomarkers of exposure to new and emerging tobacco delivery products

Accurate and reliable measurements of exposure to tobacco products are essential for identifying and confirming patterns of tobacco product use and for assessing their potential biological effects in both human populations and experimental systems. Due to the introduction of new tobacco-derived products and the development of novel ways to modify and use conventional tobacco products, precise and specific assessments of exposure to tobacco are now more important than ever. Biomarkers that were developed and validated to measure exposure to cigarettes are being evaluated to assess their use for measuring exposure to these new products. Here, we review current methods for measuring exposure to new and emerging tobacco products, such as electronic cigarettes, little cigars, water pipes, and cigarillos. Rigorously validated biomarkers specific to these new products have not yet been identified. Here, we discuss the strengths and limitations of current approaches, including whether they provide reliable exposure estimates for new and emerging products. We provide specific guidance for choosing practical and economical biomarkers for different study designs and experimental conditions. Our goal is to help both new and experienced investigators measure exposure to tobacco products accurately and avoid common experimental errors. With the identification of the capacity gaps in biomarker research on new and emerging tobacco products, we hope to provide researchers, policymakers, and funding agencies with a clear action plan for conducting and promoting research on the patterns of use and health effects of these products.

Temporal variability of urinary cadmium in spot urine samples and first morning voids

Cadmium is a carcinogenic heavy metal. Urinary levels of cadmium are considered to be an indicator of long-term body burden, as cadmium accumulates in the kidneys and has a half-life of at least 10 years. However, the temporal stability of the biomarker in urine samples from a non-occupationally exposed population has not been rigorously established. We used repeated measurements of urinary cadmium (U-Cd) in spot urine samples and first morning voids from two separate cohorts, to assess the temporal stability of the samples. Urine samples from two cohorts including individuals of both sexes were measured for cadmium and creatinine. The first cohort (Home Observation of Perinatal Exposure (HOPE)) consisted of 21 never-smokers, who provided four first morning urine samples 2-5 days apart, and one additional sample roughly 1 month later. The second cohort (World Trade Center-Health Program (WTC-HP)) consisted of 78 individuals, including 52 never-smokers, 22 former smokers and 4 current smokers, who provided 2 spot urine samples 6 months apart, on average. Intra-class correlation was computed for groups of replicates from each individual to assess temporal variability. The median creatinine-adjusted U-Cd level (0.19 and 0.21 μg/g in the HOPE and WTC-HP, respectively) was similar to levels recorded in the United States by the National Health and Nutrition Examination Survey. The intra-class correlation (ICC) was high (0.76 and 0.78 for HOPE and WTC-HP, respectively) and similar between cohorts, irrespective of whether samples were collected days or months apart. Both single spot or first morning urine cadmium samples show good to excellent reproducibility in low-exposure populations.

Environmental Factors Impacting Bone-Relevant Chemokines

Chemokines play an important role in normal bone physiology and the pathophysiology of many bone diseases. The recent increased focus on the individual roles of this class of proteins in the context of bone has shown that members of the two major chemokine subfamilies-CC and CXC-support or promote the formation of new bone and the remodeling of existing bone in response to a myriad of stimuli. These chemotactic molecules are crucial in orchestrating appropriate cellular homing, osteoblastogenesis, and osteoclastogenesis during normal bone repair. Bone healing is a complex cascade of carefully regulated processes, including inflammation, progenitor cell recruitment, differentiation, and remodeling. The extensive role of chemokines in these processes and the known links between environmental contaminants and chemokine expression/activity leaves ample opportunity for disruption of bone healing by environmental factors. However, despite increased clinical awareness, the potential impact of many of these environmental factors on bone-related chemokines is still ill defined. A great deal of focus has been placed on environmental exposure to various endocrine disruptors (bisphenol A, phthalate esters, etc.), volatile organic compounds, dioxins, and heavy metals, though mainly in other tissues. Awareness of the impact of other less well-studied bone toxicants, such as fluoride, mold and fungal toxins, asbestos, and chlorine, is also reviewed. In many cases, the literature on these toxins in osteogenic models is lacking. However, research focused on their effects in other tissues and cell lines provides clues for where future resources could be best utilized. This review aims to serve as a current and exhaustive resource detailing the known links between several classes of high-interest environmental pollutants and their interaction with the chemokines relevant to bone healing.

Urinary Cadmium and Risk of Invasive Breast Cancer in the Women's Health Initiative

Cadmium is a widespread heavy metal pollutant that may act as an exogenous estrogenic hormone. Environmental cadmium exposure has been associated with risk of breast cancer in retrospective studies. We prospectively assessed the relationship between cadmium exposure, evaluated by creatinine-normalized urinary cadmium concentration, and invasive breast cancer among 12,701 postmenopausal women aged ≥50 years in a Women's Health Initiative study of bone mineral density. After a median of 13.2 years of follow-up (1993-2010), 508 cases of invasive breast cancer and 1,050 comparison women were identified for a case-cohort analysis. Multivariable Cox regression was used to calculate hazard ratios and 95% confidence intervals. Risk of breast cancer was not associated with urinary cadmium parameterized either in quartiles (comparing highest quartile with lowest, hazard ratio = 0.80, 95% confidence interval: 0.56, 1.14; P for trend = 0.20) or as a log-transformed continuous variable (per 2-fold higher urinary cadmium concentration, hazard ratio = 0.94, 95% confidence interval: 0.86, 1.03). We did not observe an association between urinary cadmium and breast cancer risk in any subgroup examined, including never smokers and women with body mass index (weight (kg)/height (m)(2)) less than 25. Results were consistent in both estrogen receptor-positive and estrogen receptor-negative tumors. Our results do not support the hypothesis that environmental cadmium exposure is associated with risk of postmenopausal breast cancer.

Correlation between urinary cadmium and thyroid hormones in outdoor workers exposed to urban stressors

OBJECTIVES

The aim of this study is to evaluate whether exposure to low concentrations of cadmium (Cd) can have effects on the thyroid hormone level of outdoor workers exposed to urban pollutants.

METHODS

The study was conducted on a final sample of 277 individuals (184 males and 93 females). The environmental monitoring of Cd was evaluated through the use of portable dosimeters, while the biological monitoring was achieved through the assessment of urinary Cd and thyroid hormones. The total sample was divided according to sex and task. The Pearson's correlation coefficient among the variables was calculated after subdivision on the basis of sex and task. The multiple linear regression was performed to take into account the major confounding factors.

RESULTS

Statistical tests showed a negative correlation between urinary Cd levels and free triiodothyronine and free thyroxine and a positive correlation between urinary Cd and thyroid-stimulating hormone levels.

CONCLUSIONS

Our early results seem to point out that occupational exposure to low concentrations of Cd present in urban air affects the thyroid hormone levels in exposed workers.

Dietary Intake Estimates and Urinary Cadmium Levels in Danish Postmenopausal Women

BACKGROUND

Cadmium is a known carcinogen that can disrupt endocrine signalling. Cigarette smoking and food are the most common routes of non-occupational exposure to cadmium. Cadmium accumulates in the kidney and can be measured in urine, making urine cadmium (U-Cd) a biomarker of long-term exposure. However dietary-cadmium (D-Cd) intake estimates are often used as surrogate indicator of cadmium exposure in non-smoking subjects. It is therefore important to investigate the concordance between D-Cd estimates obtained with Food Frequency Questionnaires and U-Cd.

METHODS

U-Cd levels were compared with estimated dietary-cadmium (D-Cd) intake in 1764 post-menopausal women from the Danish Diet, Cancer and Health cohort. For each participant, a food frequency questionnaire, and measures of cadmium content in standard recipes were used to judge the daily intake of cadmium, normalized by daily caloric intake. Cadmium was measured by ICP-MS in spot urine sampled at baseline and normalized by urinary creatinine. Information on diet, socio-demographics and smoking were self-reported at baseline.

RESULTS

Linear regressions between U-Cd and D-Cd alone revealed minimal but significant positive correlation in never smokers (R2 = 0.0076, β = 1.5% increase per 1 ng Cd kcal(-1), p = 0.0085, n = 782), and negative correlation in current smokers (R2 = 0.0184, β = 7.1% decrease per 1 ng Cd kcal(-1) change, p = 0.0006, n = 584). In the full study population, most of the variability in U-Cd was explained by smoking status (R2 = 0.2450, n = 1764). A forward selection model revealed that the strongest predictors of U-Cd were age in never smokers (Δ R2 = 0.04), smoking duration in former smokers (Δ R2 = 0.06) and pack-years in current smokers (Δ R2 = 0.07). Food items that contributed to U-Cd were leafy vegetables and soy-based products, but explained very little of the variance in U-Cd.

CONCLUSIONS

Dietary-Cd intake estimated from food frequency questionnaires correlates only minimally with U-Cd biomarker, and its use as a Cd exposure indicator may be of limited utility in epidemiologic studies.

Anti-smoking legislation and its effects on urinary cotinine and cadmium levels

Anti-smoking legislation has been associated with an improvement in health indicators. Since the cadmium (Cd) body burden in the general population is markedly increased by smoke exposure, we analyzed the impact of the more restrictive legislation that came into force in Spain in 2011 by measuring Cd and cotinine in first morning urine samples from 83 adults in Madrid (Spain) before (2010) and after (2011) introduction of this law. Individual pair-wise comparisons showed a reduction of creatinine corrected Cotinine and Cd levels for non-active smokers, i. e. those which urinary cotinine levels are below 50 μg/L. After the application of the stricter law, cotinine levels in urine only decreased in non-active smokers who self-reported not to be exposed to second-hand smoke. The reduction in second hand smoke exposure was significantly higher in weekends (Friday to Sunday) than in working days (Monday to Thursday). The decrease in U-Cd was highly significant in non-active smokers and, in general, correlated with lower creatinine excretion. Therefore correction by creatinine could bias urinary Cd results, at least for cotinine levels higher than 500 μg/L. The biochemical/toxicological benefits detected herein support the stricter application of anti-smoking legislation and emphasize the need to raise the awareness of the population as regards exposure at home.

Biomarkers of tobacco smoke exposure

Diseases and death caused by exposure to tobacco smoke have become the single most serious preventable public health concern. Thus, biomarkers that can monitor tobacco exposure and health effects can play a critical role in tobacco product regulation and public health policy. Biomarkers of exposure to tobacco toxicants are well established and have been used in population studies to establish public policy regarding exposure to second-hand smoke, an example being the nicotine metabolite cotinine, which can be measured in urine. Biomarkers of biological response to tobacco smoking range from those indicative of inflammation to mRNA and microRNA patterns related to tobacco use and/or disease state. Biomarkers identifying individuals with an increased risk for a pathological response to tobacco have also been described. The challenge for any novel technology or biomarker is its translation to clinical and/or regulatory application, a process that requires first technical validation of the assay and then careful consideration of the context the biomarker assay may be used in the regulatory setting. Nonetheless, the current efforts to investigate new biomarker of tobacco smoke exposure promise to offer powerful new tools in addressing the health hazards of tobacco product use. This review will examine such biomarkers, albeit with a focus on those related to cigarette smoking.

Environmental chemical exposures and autism spectrum disorders: a review of the epidemiological evidence

In the past decade, the number of epidemiological publications addressing environmental chemical exposures and autism has grown tremendously. These studies are important because it is now understood that environmental factors play a larger role in causing autism than previously thought and because they address modifiable risk factors that may open up avenues for the primary prevention of the disability associated with autism. In this review, we covered studies of autism and estimates of exposure to tobacco, air pollutants, volatile organic compounds and solvents, metals (from air, occupation, diet, dental amalgams, and thimerosal-containing vaccines), pesticides, and organic endocrine-disrupting compounds such as flame retardants, non-stick chemicals, phthalates, and bisphenol A. We included studies that had individual-level data on autism, exposure measures pertaining to pregnancy or the 1st year of life, valid comparison groups, control for confounders, and adequate sample sizes. Despite the inherent error in the measurement of many of these environmental exposures, which is likely to attenuate observed associations, some environmental exposures showed associations with autism, especially traffic-related air pollutants, some metals, and several pesticides, with suggestive trends for some volatile organic compounds (e.g., methylene chloride, trichloroethylene, and styrene) and phthalates. Whether any of these play a causal role requires further study. Given the limited scope of these publications, other environmental chemicals cannot be ruled out, but have not yet been adequately studied. Future research that addresses these and additional environmental chemicals, including their most common routes of exposures, with accurate exposure measurement pertaining to several developmental windows, is essential to guide efforts for the prevention of the neurodevelopmental damage that manifests in autism symptoms.

Dietary cadmium exposure and risk of breast, endometrial, and ovarian cancer in the Women's Health Initiative

BACKGROUND

In vitro and animal data suggest that cadmium, a heavy metal that contaminates some foods and tobacco plants, is an estrogenic endocrine disruptor. Elevated estrogen exposure is associated with breast, endometrial, and ovarian cancer risk.

OBJECTIVES

We examined the association between dietary cadmium intake and risk of these cancers in the large, well-characterized Women's Health Initiative (WHI).

METHODS

A total of 155,069 postmenopausal women, 50-79 years of age, who were enrolled in the WHI clinical trials or observational study, participated in this study. We estimated dietary cadmium consumption by combining baseline food frequency questionnaire responses with U.S. Food and Drug Administration data on food cadmium content. Participants reported incident invasive breast, endometrial, or ovarian cancer, and WHI centrally adjudicated all cases through August 2009. We applied Cox regression to estimate adjusted hazard ratios (HRs) and 95% CIs for each cancer, comparing quintiles of energy-adjusted dietary cadmium intake.

RESULTS

Over an average of 10.5 years, 6,658 invasive breast cancers, 1,198 endometrial cancers, and 735 ovarian cancers were reported. We observed no statistically significant associations between dietary cadmium and risk of any of these cancers after adjustment for potential confounders including total dietary energy intake. Results did not differ in any subgroup of women examined.

CONCLUSIONS

We found little evidence that dietary cadmium is a risk factor for breast, endometrial, or ovarian cancers in postmenopausal women. Misclassification in dietary cadmium assessment may have attenuated observed associations.

Blood and urine levels of heavy metal pollutants in female and male patients with coronary artery disease

BACKGROUND

Heavy metal pollutants such as cadmium (Cd), lead (Pb), and mercury (Hg) are rarely the subjects of cardiovascular research although they have been suspected for decades to negatively impact the circulatory system.

METHODS

Apart from detailed anamnestic data, urinary levels of Cd and full blood levels of Pb and Hg were measured in 53 female (mean age: 68.04±7.03 years) and 111 male (mean age: 60.68±11.43 years) nonsmoking or never-smoking patients with angiographically verified and precisely quantified coronary artery disease (CAD).

RESULTS

Although Cd was quantifiable in 68.3% of subjects, only 34.1% of these patients exceeded the critical 1 μg/L Human Biomonitoring (HBM)-I level. Median Pb (20 μg/L) and Hg (0.55 μg/L) levels were lower than the HBM-I, as well as reference levels of Pb. Wine consumption was the main source for Pb, fish and wine consumption for Hg, and previous nicotine abuse for Cd. There was no correlation between Cd, Pb, or Hg and severity of CAD although severity correlated positively with atherosclerosis parameters (uric acid, creatinine, triglycerides, blood urea nitrogen, C-reactive protein) and negatively with high density lipoprotein cholesterol.

CONCLUSION

Cd levels detected in CAD patients were high compared to German and European reference levels but it could not be proven that urine levels of Cd and blood levels of Hg or Pb played a major role in the genesis of CAD, particularly when compared to well-known biomarkers such as blood pressure, glucose, and lipids.

Cadmium exposure and cancer mortality in a prospective cohort: the strong heart study

BACKGROUND

Cadmium (Cd) is a toxic metal classified as a human carcinogen by the International Agency for Research on Cancer.

OBJECTIVE

We evaluated the association of long-term Cd exposure, as measured in urine, with cancer mortality in American Indians from Arizona, Oklahoma, and North and South Dakota who participated in the Strong Heart Study during 1989-1991.

METHODS

The Strong Heart Study was a prospective cohort study of 3,792 men and women 45-74 years of age who were followed for up to 20 years. Baseline urinary Cd (U-Cd) was measured using inductively coupled plasma mass spectrometry. We assessed cancer events by annual mortality surveillance.

RESULTS

The median (interquintile range) U-Cd concentration was 0.93 (0.55, 1.63) μg/g creatinine. After adjusting for sex, age, smoking status, cigarette pack-years, and body mass index, the adjusted hazard ratios (HRs) comparing the 80th versus the 20th percentiles of U-Cd were 1.30 (95% CI: 1.09, 1.55) for total cancer, 2.27 (95% CI: 1.58, 3.27) for lung cancer, and 2.40 (95% CI: 1.39, 4.17) for pancreatic cancer mortality. For all smoking-related cancers combined, the corresponding HR was 1.56 (95% CI: 1.24, 1.96). Cd was not significantly associated with liver, esophagus and stomach, colon and rectum, breast, prostate, kidney, or lymphatic and hematopoietic cancer mortality. On the basis of mediation analysis, we estimated that the percentage of lung cancer deaths due to tobacco smoking that could be attributed to Cd exposure was 9.0% (95% CI: 2.8, 21.8).

CONCLUSIONS

Low-to-moderate Cd exposure was prospectively associated with total cancer mortality and with mortality from cancers of the lung and pancreas. The implementation of population-based preventive measures to decrease Cd exposure could contribute to reducing the burden of cancer.

Simultaneous determination of chromium, cadmium, and lead and evaluation of the correlation between chromium and cotinine in Chinese smokers

Heavy metals in tobacco caused wide public concern. To study the impact of heavy metals in smokers, 193 smokers and 58 nonsmokers were surveyed, and their urinary levels of chromium (UCr), lead (UPb), and cadmium (UCd) were assayed. In this study, UCr, UPb, and UCd in smokers (33.41 ± 14.99, 3.21 ± 1.34, 0.38 ± 0.64 μg/24 h, respectively) and nonsmokers (27.45 ± 10.49, 3.02 ± 0.88, 0.20 ± 0.16 μg/24 h, respectively) were determined by inductively coupled plasma mass spectrometry. The results showed that the content of UCr, UPb, and UCd in smokers were higher than in nonsmokers. Further analyses of correlations between the levels of urinary chromium and cotinine revealed positive relationship (correlation coefficient r = 0.51).

Urinary biomarkers of smokers' exposure to tobacco smoke constituents in tobacco products assessment: a fit for purpose approach

There are established guidelines for bioanalytical assay validation and qualification of biomarkers. In this review, they were applied to a panel of urinary biomarkers of tobacco smoke exposure as part of a "fit for purpose" approach to the assessment of smoke constituents exposure in groups of tobacco product smokers. Clinical studies have allowed the identification of a group of tobacco exposure biomarkers demonstrating a good doseresponse relationship whilst others such as dihydroxybutyl mercapturic acid and 2-carboxy-1-methylethylmercapturic acid - did not reproducibly discriminate smokers and non-smokers. Furthermore, there are currently no agreed common reference standards to measure absolute concentrations and few inter-laboratory trials have been performed to establish consensus values for interim standards. Thus, we also discuss in this review additional requirements for the generation of robust data on urinary biomarkers, including toxicant metabolism and disposition, method validation and qualification for use in tobacco products comparison studies.

Determinants and within-person variability of urinary cadmium concentrations among women in northern California

BACKGROUND

Cadmium (Cd) is a toxic metal associated with increased morbidity and mortality. Urinary Cd (U-Cd) concentration is considered a biomarker of long-term exposure.

OBJECTIVES

Our objectives were to evaluate the within-person correlation among repeat samples and to identify predictors of U-Cd concentrations.

METHODS

U-Cd concentrations (micrograms per liter) were measured in 24-hr urine samples collected from 296 women enrolled in the California Teachers Study in 2000 and a second 24-hr sample collected 3-9 months later from 141 of the participants. Lifestyle and sociodemographic characteristics were obtained via questionnaires. The Total Diet Study database was used to quantify dietary cadmium intake based on a food frequency questionnaire. We estimated environmental cadmium emissions near participants' residences using a geographic information system.

RESULTS

The geometric mean U-Cd concentration was 0.27 µg/L and the range was 0.1-3.6 µg/L. The intraclass correlation among repeat samples from an individual was 0.50. The use of a single 24-hr urine specimen to characterize Cd exposure in a case-control study would result in an observed odds ratio of 1.4 for a true odds ratio of 2.0. U-Cd concentration increased with creatinine, age, and lifetime pack-years of smoking among ever smokers or lifetime intensity-years of passive smoking among nonsmokers, whereas it decreased with greater alcohol consumption and number of previous pregnancies. These factors explained 42-44% of the variability in U-Cd concentrations.

CONCLUSION

U-Cd levels varied with several individual characteristics, and a single measurement of U-Cd in a 24-hr sample did not accurately reflect medium- to long-term body burden.

The effect of cadmium on the coagulation and fibrinolytic system in women with uterine endometrial cancer and myoma

OBJECTIVES

Cadmium (Cd) is a persistent and widespread environmental pollutant, which may constitute a potential risk factor for hormone-dependent tumors such as endometrial cancer. The vascular endothelium is an important target of cadmium toxicity, which may interfere with the coagulation cascade and fibrinolytic system. The aim of this research was to investigate whether in female patients with uterine endometrial cancer or myoma in comparison to healthy women, the concentration of cadmium in blood affects the process of coagulation and fibrinolysis.

MATERIALS AND METHODS

The study group comprised 91 women: 35 healthy (A-control), 39 with uterine myoma (B) and 17 with endometrial cancer (C), in which blood cadmium concentrations (BCd), coagulation and selected fibrinolysis parameters in plasma were assayed.

RESULTS

In the women with myoma and especially in those with endometrial cancer disturbances in coagulation and fibrinolysis were detected when compared to the healthy women. In the group of women with endometrial cancer significant changes in prothrombin index, levels of fibrinogen, fibrin D-dimer and t-PA were observed. Whereas, in the patients with myoma significant changes in prothrombin time, index of vWillebrand Factor and fibrin D-dimer level were noted. Mean BCd concentrations in subsequent groups were as follows: B - 0.91±0.81; C - 0.78±0.45 μg Cd/l and did not differ significantly in comparison with the control group (0.86±0.35 μg Cd/l). However, in each study group smokers had approximately twice as high BCd as non-smokers. Studies also showed significant associations between BCd and fibrinogen level and thrombin time among the women with myoma and endometrial cancer, as well as in healthy women. Moreover, thrombin time significantly correlated with fibrinogen level in the women studied.

CONCLUSIONS

In the patients with myoma and especially in these with endometrial cancer disturbances in coagulation and fibrinolysis parameters leading to hypercoagulability were detected. Exposure to cadmium can be one of the factors inducing these changes.

Dietary cadmium and risk of invasive postmenopausal breast cancer in the VITAL cohort

PURPOSE

The aim of the study was to estimate the association between dietary intake of cadmium, a carcinogenic heavy metal, and risk of invasive postmenopausal breast cancer.

METHODS

Study subjects were 30,543 postmenopausal women in the VITamins And Lifestyle (VITAL) cohort who completed a food frequency questionnaire (FFQ) at baseline (2000-2002). Dietary cadmium consumption was estimated by combining FFQ responses with US Food and Drug Administration data on food cadmium content. Incidence of invasive breast cancer was ascertained through linkage of the cohort to the western Washington Surveillance, Epidemiology, and End Results cancer registry through 31 December 2009. Cox regression was applied to estimate adjusted hazard ratios (aHRs) and 95 % confidence intervals (CIs) for breast cancer with increasing dietary cadmium intake, adjusted for total energy intake, smoking history, consumption of vegetables, potatoes, and whole grains, multivitamin use, education, race, body mass index, physical activity, age at first birth, postmenopausal hormone use, and mammography.

RESULTS

Vegetables and grains together contributed an average of 66 % of estimated dietary cadmium. During a mean of 7.5 years of follow-up, 1,026 invasive postmenopausal breast cancers were identified. Among 899 cases with complete covariate information, no evidence of an association between dietary cadmium intake and breast cancer risk was observed (aHR (95 % CI), highest to lowest quartile cadmium: 1.00 (0.72-1.41), p (trend) = 0.95). No evidence was found for interactions between dietary cadmium and breast cancer risk factors, smoking habits, or total intake of calcium, iron, or zinc from diet, supplements, and multivitamins.

CONCLUSIONS

This study does not support the hypothesis that dietary cadmium intake is a risk factor for breast cancer. However, non-differential measurement error in the estimate of cadmium intake is likely the most important factor that could have obscured an association.

The association between active/passive smoking and toxic metals among pregnant women in Greece

Exposure to toxic metals during pregnancy may have detrimental effects on foetal development. We assessed the role of sociodemographic characteristics and active and passive smoking on blood concentrations of metals (As, Cd, Pb, Hg, Sb, U, Mn and Mo). Venous blood drawn from 50 pregnant women, randomly selected from the mother-child birth cohort 'Rhea'. Extensive questionnaire data on active and passive smoking were collected. Urinary cotinine was measured to validate self-reported exposure and non-smoking status. Smokers had higher concentrations of Cd (1.0 µg/L) as compared with non-smokers (0.29 µg/L, P < 0.001) and a tendency for higher As and Hg. Among non-smokers, blood As and Hg concentrations were also associated with exposure to passive smoking in public venues and the family home and to overall greater secondhand smoke (SHS) exposure (As: 0.97µg/L among heavy-exposed compared with 0.20 µg/L among the low-exposed, P < 0.05; Hg: 2.1 µg/L vs. 0.9 µg/L respectively, P < 0.05). Controlling for fish and seafood intake altered the statistical significance but not the direction of the above associations. Smoking was associated with higher Cd concentrations in pregnant women, although the association between passive smoking and elevated As and Hg concentrations was indicative, however inconclusive.

Blood cadmium levels in women of childbearing age vary by race/ethnicity

The heavy metal cadmium (Cd) is long-lived in the body and low-level cumulative exposure, even among non-smokers, has been associated with changes in renal function and bone metabolism. Women are more susceptible to the adverse effects of Cd and have higher body burdens. Due to increased dietary absorption of Cd in menstruating women and the long half-life of the metal, reproductive age exposures are likely important contributors to overall body burden and disease risk. We examined blood Cd levels in women of reproductive age in the US and assessed variation by race/ethnicity. Blood Cd concentrations were compared among female NHANES participants aged 20-44, who were neither pregnant nor breastfeeding. Sample size varied primarily based on inclusion/exclusion of smokers (n=1734-3121). Mean Cd concentrations, distributions and odds ratios were calculated using SUDAAN. For logistic regression Cd was modeled as high (the upper 10% of the distribution) vs. the remainder. Overall, Mexican Americans had lower Cd levels than other groups due to a lower smoking prevalence, smoking being an important source of exposure. Among never-smokers, Mexican Americans had 1.77 (95% CI: 1.06-2.96) times the odds of high Cd as compared to non-Hispanic Whites after controlling for age and low iron (ferritin). For non-Hispanic Blacks, the odds were 2.96 (CI: 1.96-4.47) times those of non-Hispanic Whites in adjusted models. Adjustment for relevant reproductive factors or exposure to environmental tobacco smoke had no effect. In this nationally representative sample, non-smoking Mexican American and non-Hispanic Black women were more likely to have high Cd than non-Hispanic White women. Additional research is required to determine the underlying causes of these differences.

Applying tobacco carcinogen and toxicant biomarkers in product regulation and cancer prevention

Tobacco carcinogen and toxicant biomarkers are metabolites or protein or DNA adducts of specific compounds in tobacco products. Highly reliable analytical methods, based mainly on mass spectrometry, have been developed and applied in large studies of many of these biomarkers. A panel of tobacco carcinogen and toxicant biomarkers is suggested here, and typical values for smokers and nonsmokers are summarized. This panel of biomarkers has potential applications in the new and challenging area of tobacco product regulation and in the development of rational approaches to cancer prevention by establishing carcinogen and toxicant uptake and excretion in people exposed to tobacco products.

A simple method based on ICP-MS for estimation of background levels of arsenic, cadmium, copper, manganese, nickel, lead, and selenium in blood of the Brazilian population

Throughout the world, biomonitoring has become the standard for assessing exposure of individuals to toxic elements as well as for responding to serious environmental public health problems. However, extensive biomonitoring surveys require rapid and simple analytical methods. Thus, a simple and high-throughput method is proposed for the determination of arsenic (As), cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se) in blood samples by using inductively coupled plasma-mass spectrometry (ICP-MS). Prior to analysis, 200 microl of blood samples was mixed with 500 microl of 10% v/v tetramethylammonium hydroxide (TMAH) solution, incubated for 10 min, and subsequently diluted to 10 ml with a solution containing 0.05% w/v ethylenediamine tetraacetic acid (EDTA) + 0.005% v/v Triton X-100. After that, samples were directly analyzed by ICP-MS (ELAN DRC II). Rhodium was selected as an internal standard with matrix-matching calibration. Method detection limits were 0.08, 0.04, 0.5, 0.09, 0.12, 0.04, and 0.1 microg//L for As, Cd, Cu, Mn, Ni, Pb, and Se, respectively. Validation data are provided based on the analysis of blood samples from the trace elements inter-\comparison program operated by the Institut National de Sante Publique du Quebec, Canada. Additional validation was provided by the analysis of human blood samples by the proposed method and by using electrothermal atomic absorption spectrometry (ETAAS). The method was subsequently applied for the estimation of background metal blood values in the Brazilian population. In general, the mean concentrations of As, Cd, Cu, Mn, Ni, Pb, and Se in blood were 1.1, 0.4, 890, 9.6, 2.1, 65.4, and 89.3 microg/L, respectively, and are in agreement with other global populations. Influences of age, gender, smoking habits, alcohol consumption, and geographical variation on the values were also considered. Smoking habits influenced the levels of Cd in blood. The levels of Cu, Mn, and Pb were significantly correlated with gender, whereas Cu and Pb were significantly correlated with age. There were also interesting differences in Mn and Se levels in the population living in the north of Brazil compared to the south.

Assessment of heavy metal exposure via the intake of oriental medicines in Korea

Oriental medical herbs are mainly natural products that are generated by simple processes, and therefore there is the possibility of contamination with various pollutants, including heavy metals. Heavy metals produce adverse effects in humans, and the toxicities of lead (Pb) and cadmium (Cd) are well established. This study evaluated the effects of exposure to Pb and Cd via the intake of the frequent prescriptions of oriental medicines, and assessed the risk to the Korean population based on domestic data. The average daily exposures to Pb and Cd were estimated. This is the first study to evaluate exposure and risk of heavy metal intoxication through intake of oriental medicines in Korea. Despite the uncertainties and limits of the data, these results simulate realistic exposure levels.

Risk assessment of low-level cadmium and arsenic on the kidney

Cadmium (Cd) and arsenic (As) are widely distributed in the environment and are known human carcinogens. Several studies reported that chronic exposure to Cd and As produced renal injuries in humans. As one of the mechanisms, oxidative stress was suggested to play a role in the early process of Cd- and/or As-induced tubular damage in the kidney. This study was performed to evaluate the significance of urinary biomarkers, role of oxidative stress, and effect of coexposure to environmental low-level exposure to Cd and/or As in the general population. Urine samples were collected from 290 adults (86 males and 204 females). Urinary concentrations of Cd and As were measured, and kidney biomarkers of toxicity such as beta(2)-microglobulin and N-acetyl-beta-D-glucosaminidase (NAG) activity determined in urine. Urinary malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were measured as oxidative stress indices. The mean concentration of Cd was 1.21 microg/L, 0.84 microg/g creatinine, and As was 5.7 microg/L, 3.95 microg/g creatinine in urine. NAG, MDA, and 8-OHdG were positively correlated with both Cd and As in urine. Positive correlations were also observed between NAG and oxidative indices. The effects of coexposure to Cd and As on biomarkers are more pronounced than for exposure to each metal alone. These findings suggest that chronic exposure to low levels of Cd and/or As might produce tubular damage in the kidney through oxidative stress in humans.

Elevated metallothionein-bound cadmium concentrations in urine from bladder carcinoma patients, investigated by size exclusion chromatography-inductively coupled plasma mass spectrometry

Cadmium is discussed as being involved in the development of transitional cell carcinoma (TCC) of the bladder and can be observed in urine of these patients. Investigations of urinary samples from bladder cancer patients and normal controls were carried out with special emphasis on metallothionein (MT)-bound cadmium. Compounds that are constituents of urine were separated in urine samples by means of size exclusion chromatography and cadmium was monitored continuously with a hyphenated inductively coupled plasma mass spectrometry (ICP-MS) system. MT-bound cadmium was quantified by peak area integration, taking into account the intensity of the rhodium signal which was added continuously before ICP-MS detection. The obtained results show that urinary cadmium is predominantly bound to the observed MT-fraction. The median of the MT-bound cadmium concentration in the control group was found to be 0.8 microgL(-1) whereas the cancer group has a median of 1.8 microgL(-1). The variance of the data in the cancer group is much higher than in the controls. However, the urinary MT-bound cadmium is significantly elevated in the cancer group; odds-ratio test: 7.11 (95% C.I.: 1.89-26.80), taking into account the total protein content. Due to the fact that only one main cadmium-containing fraction was observed, there is no necessity to separate the MT-fraction before cadmium determination in urine samples in future studies.

Presenilin 1/gamma-secretase is associated with cadmium-induced E-cadherin cleavage and COX-2 gene expression in T47D breast cancer cells

Cadmium is a heavy metal that has multiple toxic effects on human health and has been classified as a human carcinogen. E-cadherin is a major target of cadmium; however, the roles of E-cadherin and cadmium and the mechanisms of tumor progression remain to be defined. Here, we demonstrate that cadmium increases E-cadherin processing via a gamma-secretase in the T47D breast cancer cell lines. This presenilin 1 (PS1)/gamma-secretase-dependent cleavage of E-cadherin was accompanied by changes in reactive oxygen species or calcium. E-cadherin cleavage was blocked by a PS1 dominant-negative mutant, gamma-secretase inhibitors [N-[N-(3,5-Difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester (DAPT) and L-685,486], antioxidants (N-acetylcysteine and Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride), or a calcium chelating drug 1,2-bis(o-Aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester. Immunofluorescence analysis confirmed the disappearance of E-cadherin staining at the cell surface. Those inhibitors attenuated cadmium-induced cytotoxicity. Additionally, cadmium treatment increased cell motility and invasion ability, which was abated by DAPT. Interestingly, cyclooxygenase-2 (COX-2) expression induced by cadmium was also inhibited by DAPT. The cadmium-induced cell motility and invasion ability were inhibited by a COX-2 inhibitor, NS398. Our data indicate a novel molecular mechanism that links cytotoxicity of cadmium and disrupted E-cadherin processing to adherens junctions; cadmium induces COX-2 expression via gamma-secretase, which increases cell motility and invasion ability. Understanding the downstream signaling cascades of cadmium that promote tumor progression might be a key to the development of novel therapeutic strategies.

Disulfiram promotes the conversion of carcinogenic cadmium to a proteasome inhibitor with pro-apoptotic activity in human cancer cells

The ubiquitin-proteasome system is involved in various cellular processes, including transcription, apoptosis, and cell cycle. In vitro, in vivo, and clinical studies suggest the potential use of proteasome inhibitors as anticancer drugs. Cadmium (Cd) is a widespread environmental pollutant that has been classified as a human carcinogen. Recent study in our laboratory suggested that the clinically used anti-alcoholism drug disulfiram (DSF) could form a complex with tumor cellular copper, resulting in inhibition of the proteasomal chymotrypsin-like activity and induction of cancer cell apoptosis. In the current study, we report, for the first time, that DSF is able to convert the carcinogen Cd to a proteasome-inhibitor and cancer cell apoptosis inducer. Although the DSF-Cd complex inhibited the chymotrypsin-like activity of a purified 20S proteasome with an IC(50) value of 32 micromol/L, this complex was much more potent in inhibiting the chymotrypsin-like activity of prostate cancer cellular 26S proteasome. Inhibition of cellular proteasome activity by the DSF-Cd complex resulted in the accumulation of ubiquitinated proteins and the natural proteasome substrate p27, which was followed by activation of calpain and induction of apoptosis. Importantly, human breast cancer MCF10DCIS cells were much more sensitive to the DSF-Cd treatment than immortalized but non-tumorigenic human breast MCF-10A cells, demonstrating that the DSF-Cd complex could selectively induce proteasome inhibition and apoptosis in human tumor cells. Our work suggests the potential use of DSF for treatment of cells with accumulated levels of carcinogen Cd.