Non-occupational Lead and Cadmium Exposure and Blood Pressure in Thai Men

The association between environmental cadmium exposure, blood pressure, and hypertension: a systematic review and meta-analysis

We performed a systematic and meta-analysis study to find the association between cadmium (Cd) exposure and blood pressure (BP)/hypertension (HTN) in exposed general populations. We searched main databases for literature published between year 2000 and April 15, 2021. Quality assessment was performed with the Joanna Briggs Institute (JBI) critical appraisal tools. Heterogeneity between studies was determined by I-squared (I²) statistic. The random effects model was used to determine the association between blood and urine Cd levels with hypertension. The overall standard differences in mean for Cd level in hypertensive and control groups were 3.34, 1.79, and 8.09 based on samples from blood, urine, and hair, respectively. The overall standard differences in mean for Cd level in the low and high exposure groups were - 0.795 and - 1.036 based on blood and urinary samples, respectively. Our findings indicate a positive relationship between blood and hair Cd levels and hypertension. We also found that hair is the optimal biological sample to find the relationship between Cd exposure and hypertension for both genders. However, more studies are needed to confirm these findings.

Family History of Hypertension and Cobalt Exposure Synergistically Promote the Prevalence of Hypertension

It has been previously reported that family history of hypertension (FHH) and exposure to metals are each independent risk factor for hypertension, but the interaction between the two in relation to hypertension risk has been poorly studied. The object of this study is Dong ethnic group in Guizhou, China. The impacts of exposure to metals and FHH on hypertension incidence were examined by using the restrictive cubic spline (RCS) model as well as the multivariate logistic regression model. As a result, FHH, together with cobalt and lead exposure, was identified to show independent significant correlation with hypertension incidence (P < 0.05). The risk of hypertension increased with the increase in lead and cobalt exposure quartiles. Typically, the RCS model revealed such dose-response relation. To further confirm the association of cobalt, lead, and FHH with the risk of hypertension, multiplication and addition models were used to analyze the influence of the interactions between these variables on the risk of hypertension. The results showed that there was a multiplying interaction between the influence of the FHH and cobalt on the risk of hypertension. As for the additive interaction between cobalt and FHH, the relative excess risk due to interaction (RERI) was determined to be 0.596 (95% Cl: 0.001-1.191), the attributable proportion due to interaction (AP) was calculated as 0.256 (95% Cl: 0.075-0.437), whereas the synergy index (S) was identified to be 1.814 (95% Cl: 1.080-3.047). Our study provides some limited evidence that a FHH and cobalt exposure synergistically promote the prevalence of hypertension.

A review of human biomonitoring in selected Southeast Asian countries

Rapid development and industrialization in Southeast (SE) Asia has led to environmental pollution, potentially exposing the general population to environmental contaminants. Human biomonitoring (HBM), measurement of chemical and/or their metabolites in human tissues and fluids, is an important tool for assessing cumulative exposure to complex mixtures of chemicals and for monitoring chemical exposures in the general population. While there are national HBM programs in several developed countries, there are no such national programs in most of the SE Asian countries. However, in recent years there has been progress in the field of HBM in many of the SE Asian countries. In this review, we present recent HBM studies in five selected SE Asian countries: Bangladesh, Indonesia, Malaysia, Myanmar and Thailand. While there is extensive HBM research in several SE Asian countries, such as Thailand, in other countries HBM studies are limited and focus on traditional environmental pollutants (such as lead, arsenic and mercury). Further development of this field in SE Asia would be benefited by establishment of laboratory capacity, improving quality control and assurance, collaboration with international experts and consortiums, and sharing of protocols and training both for pre-analytical and analytical phases. This review highlights the impressive progress in HBM research in selected SE Asian countries and provides recommendations for development of this field.

Hypothesis: cadmium explains, in part, why smoking increases the risk of cardiovascular disease

INTRODUCTION

Cigarette smoking is a major risk factor for cardiovascular disease via acute and chronic mechanisms, some of which remain unclear. One plausible but untested hypothesis concerns cadmium (Cd), a component of cigarette smoke, which is injurious to vascular endothelial cells and is independently associated with cardiovascular disease. To contribute to the formulation of this hypothesis, we performed a meta-analysis of the available data that consisted of cross-sectional studies useful to formulate but not test hypotheses.

METHODS

PubMed and Google Scholar were searched by combining the terms smoking, Cd, correlation, blood, human, and tobacco. Following abstract review, 10 cross-sectional studies were identified. We compared serum Cd levels between smokers and nonsmokers using standardized mean differences (SMDs) as well as correlation coefficients between smoking and Cd.

RESULTS

The estimated overall random effects SMD in Cd between smokers and nonsmokers was 1.13 (95% confidence interval [CI], .70-1.56) with significant heterogeneity (Q = 8.6, P < .001). The estimated overall random effects correlation coefficient between smoking and Cd was .54 (95% CI, .30-.72) with significant heterogeneity (Q = 71.3, P < .01).

CONCLUSIONS

Despite major inherent limitations of meta-analyses of cross-sectional studies, we believe that the data contribute to the formulation of the hypothesis that Cd explains, in part, why smokers have an increased risk of cardiovascular disease. Further research, including analytic studies designed a priori are necessary to test the hypothesis.

Heart function in magnetic resonance imaging and the mesenteric artery reactivity in rats receiving lead-contaminated drinking water

The aim of this study was to evaluate the effect of lead (Pb)-contaminated drinking water on magnetic resonance imaging (MRI)-estimated cardiac function, vascular reactivity, and serum lipids in rats. For 3 months, male Wistar rats, aged 4–6 weeks, were given drinking water with the addition of lead acetate at a concentration of 100 ppm Pb (10 rats) or water free from Pb (8 control rats). The cardiac MRI was performed at rest and under β-adrenergic stimulation on a 4.7 T scanner using electrocardiogram-triggered gradient echo (FLASH) cine sequence. After 1–2 weeks of the MRI test, experiments were performed ex vivo. After stabilization of perfusion pressure (PP), norepinephrine at doses from 0.01 to 5.0 μg was dissolved in Krebs solution, injected in a volume of 100 μl, and next infused at a concentration of 0.5 μg/ml into the isolated mesenteric artery. In this manner, preconstricted mesenteric bed was used to determine PP changes induced by acetylcholine, given at doses from 0.05 to 5.0 μg, before and during the infusion of nitric oxide synthase inhibitor (1.0 μg/ml). At the end, dobutamine (5 mg), followed by potassium chloride (10.5 mg), was injected. Lipid levels were determined enzymatically, blood Pb level was measured by the atomic absorption spectrophotometer. This study showed that Pb impairs the left ventricular systolic and diastolic function. Pb-induced changes in response to resistance of vessels to vasoactive agents may be secondary to the reduced left ventricular ejection fraction. The high-density lipoprotein subfraction 2 (HDL2) is involved in the cardiovascular effect of Pb.

Geospatial patterns of hospitalization rates for stroke with comorbid hypertension in relation to environmental sources of persistent organic pollutants: results from a 12-year population-based study

PURPOSE

Recent evidence indicates that exposure to persistent organic pollutants (POPs) is emerging as an important risk factor for atherosclerosis-related diseases, including stroke. Hypertension (HTN) is a major risk factor for stroke, and some studies suggest that exposure to POPs is also a risk factor for HTN. We hypothesized that POPs increase the environmental burden of stroke with comorbid HTN.

METHODS

A population-based study of hospitalization rates for stroke with comorbid HTN in populations presumably exposed to POPs, based on the zip code of residence, was conducted. Data on hospitalizations for stroke with comorbid HTN were obtained from the New York Statewide Planning and Research Cooperative System for 1993-2004. Relative risks, with 95% confidence intervals (RR, 95% CI), of hospitalization were estimated by multiple Poisson regression analysis.

RESULTS

RR of hospitalization for stroke with comorbid HTN was 13.4% higher in populations residing in zip codes containing or abutting environmental sources of POPs (RR = 1.134; 95% CI, 1.036-1.241; p = 0.006). Also, hospitalization rates were significantly higher in males than in females (RR = 1.397; 95% CI, 1.357-1.437; p < 0.001), in African Americans than in Caucasians (RR = 3.902; 95% CI, 3.617-4.208; p < 0.001), and in older age groups (p for trend < 0.001). These statistically significant findings of the effect of demographic factors are highly consistent with the current knowledge of stroke and serve as indirect quality indicators for our model.

CONCLUSIONS

Results of our study support the hypothesis that exposure to POPs increases the environmental burden of both stroke and HTN.

Correlations of urinary cadmium with hypertension and diabetes in persons living in cadmium-contaminated villages in northwestern Thailand: A population study

Risk for hypertension and diabetes has not been conclusively found to be a result of cadmium exposure. A population-based study was conducted in 2009 to examine the correlations of urinary cadmium, a good biomarker of long-term cadmium exposure, with hypertension and diabetes in persons aged 35 years and older who lived in the 12 cadmium-contaminated rural villages in northwestern Thailand. A total of 5273 persons were interviewed and screened for urinary cadmium, hypertension, and diabetes. The geometric mean level of urinary cadmium for women (2.4+/-2.3 microg/g creatinine) was significantly greater than that for men (2.0+/-2.2 microg/g creatinine). Hypertension was presented in 29.8% of the study population and diabetes was detected in 6.6%. The prevalence of hypertension significantly increased from 25.0% among persons in the lowest tertile of urinary cadmium to 35.0% in the highest tertile. In women, the rate of hypertension significantly increased with increasing urinary cadmium levels in both ever and never smokers, after adjusting for age, alcohol consumption, body mass index, and diabetes. In men, such association was less significantly found in never smokers. The study revealed no significant association between urinary cadmium and diabetes in either gender. Our study supports the hypothesis that environmental exposure to cadmium may increase the risk of hypertension. Risk for diabetes in relation to cadmium exposure remains uncertain in this exposed population.

Exposure to Persistent Organic Pollutants Increases Hospitalization Rates for Myocardial Infarction with Comorbid Hypertension

Studies suggest that environmental exposure to persistent organic pollutants (POPs) may be an emerging risk factor for ischemic heart disease, including acute myocardial infarction (AMI). However, some studies indicate that exposure to POPs may also be a risk factor for hypertension, a well-established risk factor for AMI. To investigate effect of POPs on the environmental burden of cardiovascular disease, a study of AMI with comorbid hypertension in populations environmentally exposed to persistent organic pollutants, based on the zip code of residence, was conducted. Data on hospital discharges for AMI with comorbid hypertension were obtained from the New York Statewide Planning and Research Cooperative System for 1993-2004. Patients residing in zip codes containing or abutting POPs contaminated sites were considered environmentally exposed. Relative risks (RR) - with corresponding 95% confidence intervals (95% CI) - of hospitalization for AMI with comorbid hypertension were estimated by Poisson regression, adjusting for known confounders. Adjusted hospitalization rates for AMI with comorbid hypertension were 12.4% higher in populations residing in proximity to a POPs site (adjusted RR = 1.124, 95% CI 1.025-1.233, p < 0.05), compared to not in proximity to a POPs site. Also, hospitalization rates for AMI with comorbid hypertension were higher in males than in females (adjusted RR = 2.157, 95% CI 2.100-2.215, p < 0.05), in African Americans than in Caucasians (adjusted RR = 1.631, 95% CI 1.483-1.794, p < 0.05), and in older age groups (p for trend <0.05). These findings are consistent with the established effects of non-modifiable risk factors and serve as indirect quality indicators for our model. In conclusion, our results support the hypothesis that environmental exposure to POPs increases the burden of cardiovascular disease in exposed populations.

Blood lead level and blood pressure of bus drivers in Bangkok, Thailand

This study aims to evaluate blood lead level (PbB) and blood pressure of bus drivers in Bangkok, Thailand, after the phasing out of lead in gasoline. The subjects comprised of 439 male bus drivers whose age ranged between 23 and 59 yr with the mean age of 42 +/- 8 yr. Average working experience was 10 +/- 7 yr. The mean of the systolic and diastolic blood pressure were 131 +/- 17 and 81 +/- 11 mmHg, respectively. PbB ranged from 2.5 to 16.2 microg/dl with the mean PbB of 6.3 microg/dl. Prevalence rate of systolic and diastolic hypertension among bus drivers were 23.0% and 18.2%, respectively. There were significant correlations between PbB and blood pressure both in systolic and diastolic blood pressure after controlling for age, BMI, alcohol consumption, smoking and physical exercise. However, the data on psycho-social factors which may affect on blood pressure of bus drivers were not available. Therefore, further study is needed to clarify the relationship between blood pressure and psycho-social stress among bus drivers in Bangkok. These findings suggested lead exposure at low PbB is related to increases in blood pressure.