Nephropathy in cadmium workers: assessment of risk from airborne occupational exposure to cadmium

Risk Factors of Incident Kidney Stones in Indian Adults: A Hospital-Based Cross-Sectional Study

Background The diverse manifestations of urolithiasis provide very interesting epidemiological data. This has prompted various studies to look into the etiopathogenesis of renal stones, which is believed to be multifactorial, both exogenous and endogenous. VDR Fok1 is a risk factor for renal stone formation and could cause the formation of renal stones through the mechanism of crystal induction and crystallization in the urine. While a few recent studies have shown the role of heavy metals like cadmium and lead in the formation of renal stones, the current knowledge is still insufficient. Methods This case-control prospective study was conducted in Guru Teg Bahadur (GTB) Hospital, a tertiary care facility in Delhi with 30 cases and 30 controls. Patients visiting the department of surgery between November 2011 and April 2013 were enrolled in the study. Cases were defined as patients with renal stones diagnosed on the basis of history and radiological investigations. Controls were selected from the patients admitted to the department of surgery for reasons other than renal stones. The study protocol was approved by the Institutional Ethical Committee of the University College of Medical Sciences, GTB Hospital, Delhi. Written informed consent was obtained from all patients. A structured questionnaire was used to collect data. Metal levels were analyzed by an atomic absorption spectrophotometer (Shimadzu Flame AA-680, Shimadzu Corp., Kyoto, Japan) at Delhi University. The vitamin D receptor gene was measured using genomic DNA. Horizontal agarose gel electrophoresis was used for the quantification of the genomic DNA. Results There were 30 cases and 30 controls in the study. Stress was more prevalent among cases (63%) compared to controls (36%). Nearly 83% of cases had the ff allele of the Vitamin D receptor gene compared to 46% of controls. The median arsenic and lead levels were higher among cases compared to controls. In the unadjusted model of logistic regression, we found stressed patients had three times higher odds of developing renal stones compared to non-stressed patients (OR (95% CI): 2.98 (1.04-8.52); p=0.04). Similarly, patients with higher blood concentrations of arsenic and lead had higher odds of developing renal stones compared to those with lower concentrations.  Conclusions There was a definitive role of heavy metals, including lead, cadmium, and arsenic, seen with renal stones. A significant association was seen between the ff allele of VDR polymorphism (Fok1 enzymes) and patients with renal stones. Other parameters, including male and stress factors, seem to have an important role in renal stone formation.

Association of Blood Pressure with Blood Lead and Cadmium Levels in Korean Adolescents: Analysis of Data from the 2010-2016 Korean National Health and Nutrition Examination Survey

BACKGROUND

We evaluated the association of blood pressure (BP) with blood levels of cadmium, lead, and cadmium and lead together (cadmium + lead) in a representative sample of adolescents from Korea.

METHODS

We used 2010-2016 data from the Korean National Health and Nutrition Examination Survey. This cross-sectional study enrolled adolescents aged at 10-18 years-old who completed a health examination survey and had blood measurements of lead and cadmium. The association of adjusted mean differences in diastolic and systolic BP with doubling of blood lead and cadmium were estimated by regression of BP against log₂-transformed blood metals and their quartiles after covariate adjustment. Adjusted odds ratio for prehypertension were calculated for log₂-transformed blood levels of lead and cadmium and their quartiles.

RESULTS

Our analysis of adolescents in Korea indicated that blood levels of lead and cadmium were not significantly associated with increased BP or risk of prehypertension. However, the cadmium + lead level was associated with prehypertension. Previous studies showed that blood levels of lead and cadmium were associated with increased BP and risk of hypertension in adult populations. We found no such association in Korean adolescents.

CONCLUSION

We found that the cadmium + lead level was associated with prehypertension. The differences between adults and adolescents are because adolescents generally have lower levels of these blood metals or because adolescents only rarely have hypertension.

Environmental and occupational exposure to cadmium in Iran: a systematic review

INTRODUCTION

Cadmium (Cd) is one of the heavy metals that have negative effects on human health. In Iran, there is no policy to regularly measure Cd in the general population. However, some studies have been performed on special groups and in different cities of Iran. This paper has reviewed these studies and human contamination levels in Iran.

METHOD AND MATERIALS

All accessible electronic information resources such as Scientific Information Database (SID), Magiran, IranMedex, PubMed, Web of Knowledge, Google Scholar and Science Direct were searched, with relevant phrases and their Persian translations. The search included all studies conducted in Iran and listed in the databases until March 15, 2016.

RESULTS

Eventually, 18 articles were selected from 25 retrieved articles. Cd was higher among industrial workers exposed to Cd. In the general population, Cd was higher among smokers and in people with environmental exposure from living in industrial areas.

CONCLUSION

Considering the high Cd contamination in the workers of industries, it seems to be necessary to do surveillance in this group through periodic regular check-ups and avoiding unnecessary exposure to Cd as much as possible. Also due to the high concentration of Cd in smokers, there should be more awareness of the damaging effects of smoking, especially among pregnant women, and more attention to local industries, especially those dealing with Cd, is necessary. These industries should be kept at a safe distance from residential areas.

Is Urinary Cadmium a Biomarker of Long-term Exposure in Humans? A Review

Cadmium is a naturally-occurring element, and humans are exposed from cigarettes, food, and industrial sources. Following exposure, cadmium accumulates in the kidney and is slowly released into the urine, usually proportionally to the levels found in the kidneys. Cadmium levels in a single spot urine sample have been considered indicative of long-term exposure to cadmium; however, such a potentially exceptional biomarker requires careful scrutiny. In this review, we report good to excellent temporal stability of urinary cadmium (intraclass correlation coefficient 0.66-0.81) regardless of spot urine or first morning void sampling. Factors such as changes in smoking habits and diseases characterized by increased excretion of proteins may produce short-term changes in urinary cadmium levels. We recommend that epidemiologists use this powerful biomarker in prospective studies stratified by smoking status, along with thoughtful consideration of additional factors that can influence renal physiology and cadmium excretion.

Benchmark dose for cadmium exposure and elevated N-acetyl-β-D-glucosaminidase: a meta-analysis

Cadmium (Cd) is a well-known nephrotoxic contaminant, and N-acetyl-β-D-glucosaminidase (NAG) is considered to be an early and sensitive marker of tubular dysfunction. The link between Cd exposure and NAG level enables us to derive the benchmark dose (BMD) of Cd. Although several reports have already documented urinary Cd (UCd)-NAG relationships and BMD estimations, high heterogeneities arise due to the sub-populations (age, gender, and ethnicity) and BMD methodologies being employed. To clarify the influences that these variables exert, firstly, a random effect meta-analysis was performed in this study to correlate the UCd and NAG based on 92 datasets collected from 30 publications. Later, this established correlation (Ln(NAG) = 0.51 × Ln(UCd) + 0.83) was applied to derive the UCd BMD₅ of 1.76 μg/g creatinine and 95 % lower confidence limit of BMD₅ (BMDL₅) of 1.67 μg/g creatinine. While the regressions for different age groups and genders differed slightly, it is age and not gender that significantly affects BMD estimations. Ethnic differences may require further investigation given that limited data is currently available. Based on a comprehensive and systematic literature review, this study is a new attempt to quantify the UCd-NAG link and estimate BMD.

Reporting of occupational and environmental research: use and misuse of statistical and epidemiological methods

OBJECTIVES

To report some of the most serious omissions and errors which may occur in papers submitted to Occupational and Environmental Medicine, and to give guidelines on the essential components that should be included in papers reporting results from studies of occupational and environmental health.

METHODS

Since 1994 Occupational and Environmental Medicine has used a panel of medical statisticians to review submitted papers which have a substantial statistical content. Although some studies may have genuine errors in their design, execution, and analysis, many of the problems identified during the reviewing process are due to inadequate and incomplete reporting of essential aspects of a study. This paper outlines some of the most important errors and omissions that may occur. Observational studies are often the preferred choice of design in occupational and environmental medicine. Some of the issues relating to design, execution, and analysis which should be considered when reporting three of the most common observational study designs, cross sectional, case-control, and cohort are described. An illustration of good reporting practice is given for each. Various mathematical modelling techniques are often used in the analysis of these studies, the reporting of which causes a major problem to some authors. Suggestions for the presentation of results from modelling are made.

CONCLUSIONS

There is increasing interest in the development and application of formal "good epidemiology practices". These not only consider issues of data quality, study design, and study conduct, but through their structured approach to the documentation of the study procedures, provide the potential for more rigorous reporting of the results in the scientific literature.

T cells reactive to an inducible heat shock protein induce disease in toxin-induced interstitial nephritis

T cells reactive against immunodominant regions of inducible heat shock proteins (HSPs) have been identified in the chronic inflammatory lesions of several experimental autoimmune diseases. Since HSPs are known to be induced by a number of renal tubular epithelial cell toxins associated with chronic interstitial nephritis, we investigated the relevance of HSP expression and T cell reactivity to HSP70 in a model of progressive inflammatory interstitial nephritis. Chronic administration of cadmium chloride (CdCl2) to SJL/J mice induces HSP70 expression in renal tubular cells 4-5 wk before the development of interstitial mononuclear cell infiltrates. CdCl2 also induces HSP70 expression in cultured tubular epithelial cells from SJL/J mice. CD4+, TCR-alpha/beta+ T cell lines specific for an immunodominant HSP peptide are cytotoxic to heat stressed or CdCl2-treated renal tubular cells. Such HSP-reactive T cells mediate an inflammatory interstitial nephritis after adoptive transfer to CdCl2-treated mice at a time when immunoreactive HSP70 is detectable in the kidneys, but before the development of interstitial mononuclear cell infiltrates. T cells isolated from the nephritic kidneys of mice treated with CdCl2 for 13 wk are also cytotoxic to heat shocked or cadmium-treated tubular cells. These kidney-derived T cells additionally induced interstitial nephritis after passive transfer, indicating their pathogenic significance. Our studies strongly support a role for HSP-reactive T cells in CdCl2-induced interstitial nephritis and suggest that the induction of HSPs in the kidney by a multitude of "non-immune" events may initiate or facilitate inflammatory damage by HSP-reactive lymphocytes.

The mortality of lead smelter workers: an update

OBJECTIVES

Mortality studies of lead workers have shown excesses of nonmalignant renal disease and cerebrovascular disease. Animal studies and one human study have shown excess kidney cancer. We have updated a mortality study of male lead smelter workers (n = 1990).

METHODS

An analysis was conducted using standard life table techniques. The updated analysis added 11 years of follow-up and 363 new deaths.

RESULTS

The original study had found elevated but nonsignificant risks for kidney cancer, stroke, and nonmalignant renal disease, probably attributable to lead exposure. Deaths from accidents and nonmalignant respiratory disease were significantly elevated, but probably not as a result of lead exposure. In the updated study, no new deaths from nonmalignant renal disease occurred (9 observed, standardized mortality ratio = 1.21). Three more deaths from kidney cancer were observed, yielding a standardized mortality ratio of 1.93 (9 observed, 95% CI = 0.88, 3.67), which increased for those who had worked in areas with the highest lead exposure (8 observed, standardized mortality ratio = 2.39, 95% CI = 1.03, 4.71). Cerebrovascular disease remained elevated for those with more than 20 years of exposure (26 observed, standardized mortality ratio = 1.41, 95% CI = 0.92, 2.07).

CONCLUSIONS

This cohort with high lead exposure showed a diminishing excess of death from nonmalignant renal disease, a continued excess from kidney cancer, and an excess of cerebrovascular disease only in those with longest exposure to lead.

Urinary cadmium and N-acetyl-beta-D-glucosaminidase excretion of inhabitants living in a cadmium-polluted area

Urinary cadmium (Cd), N-acetyl-beta-D-glucosaminidase (NAG), and creatinine levels were determined for 400 inhabitants living in Cd-polluted districts of Annaka City in Gunma Prefecture, Japan. The Cd pollution was mainly due to falling dust from a zinc smelter factory according to seasonal winds. The Cd-polluted areas were divided into five administrative districts around the factory. The geometric mean of the urinary Cd level of the inhabitants in the five districts, Nodono, Iwai, Ooya, Nakajyuku, and Itahana, were 2.95, 2.66, 2.45, 1.97, and 1.67 micrograms/g creatinine, respectively. The geometric means for Nodono and Iwai are statistically larger than that for Itahana (P less than 0.01). These results were well explained by the wind direction and proximity to the factory. In addition, a two-way analysis of variance on the urinary Cd level was made using place of residence and smoking habits. The effect was mainly due to the place of residence, and no interactions were found. There were statistically significant differences in NAG excretion among the five groups, but no difference could be found between two groups using a multiple comparison. Pearson's correlation coefficient between the logarithm of urinary Cd content and that of NAG was 0.203, but statistically significant (r = 0.462 without creatinine correction; P less than 0.01). The present results indicate the association of urinary Cd and NAG levels in a Cd-exposed population whose geometric mean of urinary Cd content is about 2 micrograms/g creatinine. We recommend a continuous survey of the minimum health effects of the Cd pollution using urinary levels of Cd and protein including NAG.

Urinary cadmium and blood pressure: results from the NHANES II survey

Relationships between urinary cadmium levels and blood pressure were examined in a sample of 951 adult men and women who participated in the Second National Health and Nutritional Examination Survey (NHANES II). Among all participants, positive relationships were seen between urinary cadmium levels and both systolic and diastolic blood pressure (p less than 0.05 and p less than 0.01, respectively), after adjusting for age, sex, race, relative body weight, smoking status, and hypertensive medication use. However, analyses for subgroups determined by sex and smoking status were inconsistent. Among current smokers, urinary cadmium levels were significantly positively associated with both systolic and diastolic blood pressure for women, and with diastolic blood pressure for men. Yet among former smokers and lifelong nonsmokers of both sexes, urinary cadmium was not significantly associated with either systolic or diastolic blood pressure. Evidence that some hypertensive medications increase urinary cadmium excretion suggests that the positive associations seen among current smokers may reflect high urinary cadmium levels among hypertensives induced by hypertensive treatment. After treated hypertensives were removed from the analysis, regression coefficients relating blood pressure to cadmium dropped by a factor of two and lost statistical significance. We conclude that the present data provide little support for a causal association between systemic cadmium and hypertension at nonoccupational exposure levels. Further, conflicting results of previous studies may reflect failure to control adequately for age, smoking status, and hypertensive treatment.