The relationship between occupational exposure to lead and manifestation of cardiovascular complications in persons with arterial hypertension

Association Between Blood Lead Levels and Hypertension in a South Indian Population: A Case-Control Study

Background

Exposure to lead and its accumulation in the body can lead to progressive adverse effects, including increased blood pressure which is associated with the onset of cardiovascular diseases. In this study, we aimed to determine the relationship between blood lead levels and blood pressure. In addition, we compared blood lead levels between hypertensives and normotensives to determine relationships, if any, between lead exposure and high blood pressure.

Methodology

This was a hospital-based, case-control study. In total, 102 individuals (hypertensives = 51, normotensives = 51) were included in this study. Hypertensive patients (defined as systolic blood pressure (SBP) of ≥140 mmHg, diastolic blood pressure (DBP) of ≥90 mmHg, or taking antihypertensive medication for regulating blood pressure) were considered to be study cases and normotensive individuals were considered to be study controls. Blood lead levels were compared between the two groups, and the effects of blood lead levels on SBP and DBP were estimated. The blood lead levels were measured using optical emission spectrometry.

Results

The mean blood lead level among hypertensive individuals (5.5743 ± 1.77 µg/dL) was significantly higher compared to normotensive individuals (4.5029 ± 1.3213 µg/dL, P = 0.001). A positive correlation was detected between blood lead levels and SBP (r = 0.304, P = 0.002). However, no significant correlation was found between blood lead levels and DBP.

Conclusions

Blood lead levels were significantly higher in hypertensive patients compared to normotensive individuals. A significant positive correlation was observed between blood lead levels and SBP.

Relations of blood lead levels to echocardiographic left ventricular structure and function in preschool children

Lead (Pb) has been proved to exert adverse effect on human cardiovascular system. However, the cardiotoxicity of Pb on children is still unclear. The aim of this study was to evaluate left ventricular (LV) structure and function, by using echocardiographic indices, in order to elucidate the effect of Pb on low-grade inflammation related to left ventricle in healthy preschool children. We recruited a total of 486 preschool children, 310 from Guiyu (e-waste-exposed area) and 176 from Haojiang (reference area). Blood Pb levels, complete blood counts, and LV parameters were evaluated. Associations between blood Pb levels and LV parameters and peripheral leukocyte counts were analyzed using linear regression models. The median blood level of Pb and the counts of white blood cells (WBCs), monocytes, and neutrophils were higher in exposed group. In addition, the exposed group showed smaller left ventricle (including interventricular septum, LV posterior wall, and LV mass index) and impaired LV systolic function (including LV fractional shortening and LV ejection fraction) regardless gender. After adjustment for confounding factors, elevated blood Pb levels were significantly associated with higher counts of WBCs and neutrophils, and lower levels of LV parameters. Furthermore, counts of WBCs, monocytes, and neutrophils were negatively correlated with LV parameters. Taken together, smaller left ventricle and impaired systolic function were found in e-waste-exposed children and associated with chronic low-grade inflammation and elevated blood Pb levels. It indicates that the heart health of e-waste-exposed children is at risk due to the long-term environmental chemical insults.

Use of an Exposome Approach to Understand the Effects of Exposures From the Natural, Built, and Social Environments on Cardio-Vascular Disease Onset, Progression, and Outcomes

Obesity, diabetes, and hypertension have increased by epidemic proportions in recent years among African Americans in comparison to Whites resulting in significant adverse cardiovascular disease (CVD) disparities. Today, African Americans are 30% more likely to die of heart disease than Whites and twice as likely to have a stroke. The causes of these disparities are not yet well-understood. Improved methods for identifying underlying risk factors is a critical first step toward reducing Black:White CVD disparities. This article will focus on environmental exposures in the external environment and how they can lead to changes at the cellular, molecular, and organ level to increase the personal risk for CVD and lead to population level CVD racial disparities. The external environment is defined in three broad domains: natural (air, water, land), built (places you live, work, and play) and social (social, demographic, economic, and political). We will describe how environmental exposures in the natural, built, and social environments "get under the skin" to affect gene expression though epigenetic, pan-omics, and related mechanisms that lead to increased risk for adverse CVD health outcomes and population level disparities. We also will examine the important role of metabolomics, proteomics, transcriptomics, genomics, and epigenomics in understanding how exposures in the natural, built, and social environments lead to CVD disparities with implications for clinical, public health, and policy interventions. In this review, we apply an exposome approach to Black:White CVD racial disparities. The exposome is a measure of all the exposures of an individual across the life course and the relationship of those exposures to health effects. The exposome represents the totality of exogenous (external) and endogenous (internal) exposures from conception onwards, simultaneously distinguishing, characterizing, and quantifying etiologic, mediating, moderating, and co-occurring risk and protective factors and their relationship to disease. Specifically, it assesses the biological mechanisms and underlying pathways through which chemical and non-chemical environmental exposures are associated with CVD onset, progression and outcomes. The exposome is a promising approach for understanding the complex relationships among environment, behavior, biology, genetics, and disease phenotypes that underlie population level, Black: White CVD disparities.

The Relationship between Exposure to Lead-Containing Welding Fumes and the Levels of Reproductive Hormones

Background

Inhalation of lead oxide fumes may cause lead poisoning. Lead has been proven to have harmful effects on different organs. This study aimed to investigate the relationship between the concentration of lead fumes and the levels of reproductive hormones among exposed welders.

Methods

A total number of 165 individuals of a construction industry of water pipelines, including 85 welders as the exposure group and 80 administrative staff as the non-exposure group were selected for study. The National Institute for Occupational Safety and Health (NIOSH) 7300 method was used for the purpose of sampling and analysis of lead fumes. Likewise, the NIOSH 8003 method was employed to determine the blood lead level. The level of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone were measured by Chemiluminescence immunoassay(CLIA) test. Data analyses were done by SPSS ver.21 using descriptive statistics, Student›s t-test and Spearman›s correlation test.

Results

The average concentration of lead fumes in the breathing zone and blood were 0.57 ± 0.12 mg/m³ and 460.28 ± 93.65 μg/L, correspondingly, which both were significantly higher than threshold limit values (TLV) and biological exposure index (BEI) recommended by American Conference of Governmental Industrial Hygienists (ACGIH)(P < 0.05). The mean levels of LH and FSH were higher in the exposed group than those in the control group (P < 0.05), however, the mean levels of testosterone were lower in the exposed group compared to non-exposed ones (P < 0.05). A strong correlation was found between the concentration of lead fumes and the blood lead levels (r = 0.82; P = 0.003). Blood lead levels were inversely related to the testosterone levels and directly related to LH (r = 0.72; P = 0.004) and FSH (r = 0.78; P = 0.001) levels.

Conclusions

Occupational exposure to metal fumes containing lead among welders may alter the level of sexual hormones and potentially harm the reproductive system.

Association between blood lead level and blood pressure: An occupational population-based study in Jiangsu province, China

Studies about the association between lead exposure and the elevation of blood pressure and risk of hypertension are varied, while available data on blood lead levels (BLL) in workers with lead-exposure are scarce. This research aimed to evaluate associations between BLL and blood pressure in an occupational population-based study in Jiangsu province, China. We enrolled 21,688 workers in this study. Information on socioeconomic and occupational background was obtained with face-to-face interviews. BLL, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured, and hypertension status was confirmed. We found that workers in mini-factories had the highest average BLL (20.3 μg/dL; 95% CI, 19.0-21.6 μg/dL) for overall participants. The employees in private factories had higher BLL (9.6 μg/dL; 95% CI, 9.5-9.8 μg/dL). However, BLL was much lower (4.0 μg/dL; 95%CI, 3.7-4.2 μg/dL) in state-owned factories. Participants working in the electrical machinery and equipment manufacturing industry had higher BLL (9.1 μg/dL; 95% CI, 9.0-9.3μg/dL). Compared to those workers with ≤ 4.6 μg/dL BLL, workers with > 17.5 μg/dL BLL presented 1.34 mmHg and 0.70 mmHg average difference in SBP and DBP, respectively. The adjusted OR for hypertension was 1.11 (95%CI, 1.08-1.15) compared to the workers with > 17.5 μg/dL BLL and to those with ≤ 4.6 μg/dL BLL. In summary, we found that BLL was positively associated with SBP and DBP and with the morbidity of hypertension in occupational populations with a high concentration of lead exposure. It is important to formulate new standards of blood lead levels to screen for elevated lead exposure. In addition, a series of new systems of risk assessment should be established to further reduce and prevent lead exposure.

Genetic variability in the system of natriuretic B peptide and principal toxicological parameters in workers exposed to lead

The study was aimed at evaluating the influence of selected polymorphisms of natriuretic peptide B precursor (NPPB) and natriuretic peptide receptor C (NPR3) genes on blood lead concentration (Pb-B) and blood zinc protoporphyrin concentration (ZnPP) in persons occupationally exposed to lead. Investigations were conducted on 360 persons (mean age: 44.49±9.62years), workers exposed to lead compounds. The analysis examined four polymorphisms of BNP gene, i.e.,: rs198388, rs198389, rs632793, and rs6676300; as well as one polymorphism of receptor C for natriuretic peptides, i.e., rs1421811. Heterozygosity in locus rs632793 of NPPB gene may result in higher concentrations of Pb-B, while allele A in locus rs632793 of NPPB gene seems to determine higher concentrations of ZnPP in persons occupationally exposed to lead. Workers exposed to lead and carrying allele C in locus rs198388 of NPPB gene, particularly in the heterozygotic setup, seem to be predisposed to present higher concentrations of ZnPP. Carriership of A allele in locus rs198389 of NPPB gene probably determines higher concentrations of ZnPP in study group. In summary, among persons occupationally exposed to lead, certain relationships were demonstrated between rs632793, rs198388 and rs198389 polymorphisms of NPPB gene and principal toxicological parameters characterizing exposure to lead.

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.

Elevated circulating levels of copper and nickel are found in elderly subjects with left ventricular hypertrophy

Identified risk factors for left ventricular hypertrophy (LVH) are hypertension, diabetes and obesity. However, since these risk factors only explain a part of the variation in left ventricular mass, we investigated if trace and heavy metals might also play a role in LVH. In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, left ventricular mass index (LVMI) and relative wall thickness (RWT) were determined by echocardiography together with eleven different trace and heavy metals in 993 subjects aged 70 years. Only copper levels were significantly related to LVMI following adjustment for sex, blood pressure, antihypertensive treatment, diabetes and body mass index (BMI) (p<0.0001). However, both copper (Cu) and nickel (Ni) were related to RWT following adjustment (p<0.0001). When divided into four geometric groups, both Cu and Ni were elevated in subjects with concentric remodelling and concentric LVH, but not in those with eccentric hypertrophy, when compared to subjects with a normal left ventricle. No relationships were found for zinc, aluminium, manganese, molybdenum, mercury, lead, cadmium, cobalt or chromium. Elevated levels of copper and nickel are found in elderly subjects with LVH, especially of the concentric type, following adjustment for known risk factors for LVH.

Environmental and occupational exposure to lead as a potential risk factor for cardiovascular disease

We have evaluated current knowledge on relations between environmental and occupational exposure to lead with a strong emphasis on cardiovascular disease risk factors, such as the influence of lead compounds on lipid disturbances and arterial blood pressure. In addition, "novel" biochemical and vascular risk factors for cardiovascular diseases were discussed, as well as the combination of lead exposure and genetic predisposition to cardiovascular diseases. Occupationally and educationally, awareness of the unfavourable effects of lead on cardiovascular diseases risk factors should be emphasised. Indeed, accurate identification of the various mechanisms that might account for the effects of lead on the cardiovascular system should be of the highest priority in this field of research.