An updated systematic review on the association between Cd exposure, blood pressure and hypertension.

BACKGROUND: Since the first report by Perry et al. (1955), most studies affirmed the hypertensive effects of cadmium (Cd) in humans. Nonetheless, conclusions between studies remain inconsistent. OBJECTIVE: The aim of this study was to reevaluate the evidence for a potential relationship between Cd exposure and altered blood pressure and/or hypertension, focusing on studies published between January 2010 and March 2020. METHODS: We reviewed all observational studies from database searches (PubMed and SCOPUS) on Cd exposure and blood pressure or hypertension. We extracted information from studies that provided sufficient data on population characteristics, smoking status, exposure, outcomes, and design. RESULTS: Thirty-eight studies met our inclusion criteria; of those, twenty-nine were cross sectional, three case control, five cohort and one interventional study. Blood or urinary Cd levels were the most commonly used biomarkers. CONCLUSIONS: A positive association between blood Cd levels and blood pressure and/or hypertension was identified in numerous studies at different settings. Limited number of representative population-based studies of never-smokers was observed, which may have confounded our conclusions. The association between urinary Cd and blood pressure and/or hypertension remains uncertain due to conflicting results, including inverse relationships with lack of strong mechanistic support. We point to the urgent need for additional longitudinal studies to confirm our findings.

Blood cadmium levels and sources of exposure in an adult urban population in southern Brazil.

BACKGROUND: Cadmium (Cd) is a toxic metal that is widely present in the environment due to geologic and anthropogenic sources. Exposures to high Cd levels may cause nephrotoxicity, carcinogenicity, pulmonary and cardiovascular disease, among others. The goal of this study was to investigate in an adult urban population whether an association exists between sources and levels of Cd exposure and blood Cd concentrations. METHODS: Using a census-based design, a total of 959 adults, aged 40 years or older, were randomly selected. Information on socio-demographics, dietary, and lifestyle background was obtained by household interviews. Blood Cd levels were measured by inductively coupled-plasma mass spectrometry. Geometric means (GM) (95% CI) and the 50th percentile were determined, stratified by sex, age, race, education, income class, smoking status, consumption of vegetables, red meat and milk, occupation and blood pressure. To assess the association between Cd exposure and the aforementioned variables, we estimated the geometric mean ratio (GMR) (95%CI) of blood Cd concentrations. RESULTS AND CONCLUSION: The geometric mean (95%CI) of blood Cd levels in the total population was 0.25 (0.22, 0.27) ug/dL. In a univariate analysis, significantly higher blood Cd levels were found in men (p < 0.001), current and former smokers (p < 0.001), alcohol drinkers (p < 0.001), those who never or almost never consumed milk (p < 0.001), and in subjects with higher diastolic blood pressure (p = 0.03). Significant correlations were found between the number of cigarettes consumed daily and blood Cd levels. Multivariate analysis confirmed higher blood Cd concentrations were associated with alcohol consumption (GMR 95%CI = 1.28, 1.04-1.59) and in former and current smokers (GMR 95% IC = 1.33, 1.06-1.67 and 4.23, 3.24-5.52, respectively). Our results shed novel information on variables associated with blood Cd levels in an urban Brazilian population, and should encourage additional research to prevent environmental Cd exposure, both in Brazil and globally.