Chronic Stress and Cardiovascular Disease among Individuals Exposed to Lead: A Pilot Study

The Association of Cytomegalovirus and Allostatic Load by Country of Birth and Length of Time in the United States

BACKGROUND

Cytomegalovirus (CMV) is a highly prevalent virus with a worldwide distribution. It typically remains dormant in most individuals until reactivation. Immunocompromised states are known to be potential causes for CMV reactivation. Current research has shown a link in the decline of immigrant health among those living in the US for an extended period, though the impact of CMV on this is not clear.

METHODS

This study investigated the association between country of birth, duration of US residency, allostatic load, and latent cytomegalovirus infection (CMV IgG) in a sample of US adults aged 20-49. The data utilized for our analysis was obtained from the National Health and Nutrition Examination Survey (NHANES) conducted between 2001 and 2004. Allostatic load, an index measuring the cumulative physiological strain on the body as it strives to regain stability in the presence of chronic stress, provided a valuable approach to assess stress within the context of CMV exposure. Logistic regression modeling was employed to estimate odds ratios and confidence intervals for the analysis. The chi-square test of association and Cramer's V statistic were used to assess the correlation among categorical variables, while Pearson's correlation coefficient was applied to evaluate the relationship between continuous variables. The results revealed that individuals born outside the US and those with less than 20 years of residency in the US exhibited significantly higher proportions of positive CMV IgG compared to individuals born in the US. Specifically, individuals born outside the US had more than triple the odds of CMV IgG when adjusting for the AL index (OR = 3.69, p-value = 0.0063). A similar trend was observed when examining AL risk based on the duration of US residency. Furthermore, age and sex were identified as significant predictors (p-value < 0.05) of AL risk, considering the individual's country of birth. In summary, the findings of this study significantly enhance our comprehension of the intricate interplay between cytomegalovirus (CMV) and allostatic load (AL). The investigation sheds light on how CMV and AL interact within specific demographic contexts, providing valuable insights into the underlying risk factors for CMV infection.

Combined Effects of Multiple Per- and Polyfluoroalkyl Substances Exposure on Allostatic Load Using Bayesian Kernel Machine Regression

This study aims to investigate the combined effects of per- and polyfluoroalkyl substances (PFAS) on allostatic load, an index of chronic stress that is linked to several chronic diseases, including cardiovascular disease and cancer. Using data from the National Health and Nutrition Examination Survey (NHANES) 2007-2014, this study examines the relationship between six PFAS variables (PFDE, PFNA, PFOS, PFUA, PFOA, and PFHS) and allostatic load using Bayesian Kernel Machine Regression (BKMR) analysis. The study also investigates the impact of individual and combined PFAS exposure on allostatic load using various exposure-response relationships, such as univariate, bivariate, or multivariate models. The analysis reveals that the combined exposure to PFDE, PFNA, and PFUA had the most significant positive trend with allostatic load when it was modeled as a binary variable, while PFDE, PFOS, and PFNA had the most significant positive trend with allostatic load when modeled as a continuous variable. These findings provide valuable insight into the consequences of cumulative exposure to multiple PFAS on allostatic load, which can help public health practitioners identify the dangers associated with potential combined exposure to select PFAS of interest. In summary, this study highlights the critical role of PFAS exposure in chronic stress-related diseases and emphasizes the need for effective strategies to minimize exposure to these chemicals to reduce the risk of chronic diseases. It underscores the importance of considering the combined effects of PFAS when assessing their impact on human health and offers valuable information for policymakers and regulators to develop strategies to protect public health.

The Association of Combined Per- and Polyfluoroalkyl Substances and Metals with Allostatic Load Using Bayesian Kernel Machine Regression

Background/Objective: This study aimed to investigate the effect of exposure to per- and polyfluoroalkyl substances (PFAS), a class of organic compounds utilized in commercial and industrial applications, on allostatic load (AL), a measure of chronic stress. PFAS, such as perfluorodecanoic acid (PFDE), perfluorononanoic acid (PFNA), perfluorooctane sulfonic acid (PFOS), perfluoroundecanoic acid (PFUA), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHS), and metals, such as mercury (Hg), barium (Ba), cadmium (Cd), cobalt (Co), cesium (Cs), molybdenum (Mo), lead (Pb), antimony (Sb), thallium (TI), tungsten (W), and uranium (U) were investigated. This research was performed to explore the effects of combined exposure to PFAS and metals on AL, which may be a disease mediator. Methods: Data from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2014 were used to conduct this study on persons aged 20 years and older. A cumulative index of 10 biomarkers from the cardiovascular, inflammatory, and metabolic systems was used to calculate AL out of 10. If the overall index was ≥ 3, an individual was considered to be chronically stressed (in a state of AL). In order to assess the dose-response connections between mixtures and outcomes and to limit the effects of multicollinearity and other potential interaction effects between exposures, Bayesian kernel machine regression (BKMR) was used. Results: The most significant positive trend between mixed PFAS and metal exposure and AL was revealed by combined exposure to cesium, molybdenum, PFHS, PFNA, and mercury (posterior inclusion probabilities, PIP = 1, 1, 0.854, 0.824, and 0.807, respectively). Conclusions: Combined exposure to metals and PFAS increases the likelihood of being in a state of AL.

The Association of Cytomegalovirus IgM and Allostatic Load

Background: Cytomegalovirus (CMV) is a deoxyribonucleic acid virus that affects a significant proportion of the worldwide population; after primary infection, it goes into a latent state and can be reactivated, primarily after a reduction in host immune defenses. Methods: This study evaluated the association of acute cytomegalovirus infection (CMV IgM) and Allostatic Load (AL) by sociodemographic factors using data from the National Health and Nutrition Examination Survey (NHANES) 2001–2004 among participants (aged 20–49 years). CMV infection was determined by the level of CMV IgM antibody in serum samples. AL was assessed as a combination of 10 biomarkers from the cardiovascular, inflammatory, and metabolic systems. The evaluation of the association between CMV infection and AL included descriptive statistics and logistic regression models, which were adjusted for demographic and behavioral covariates. Results: AL was more elevated among those who were older, male, those with lower education, those performing limited physical activity, and smokers. CMV was more elevated in females than males among those who consumed alcohol and cigarette smokers. In Pearson’s correlation analysis, there was a slight positive correlation between CMV IgM and AL, with triglycerides and Body Mass Index (BMI) the most strongly correlated with AL. Binary logistic regression showed no significant relationship between high AL and positive CMV IgM but did show a significant relationship between high AL and age (OR = 1.0592, 95% CI 1.0215–1.0983, p = 0.00715). The findings of this study provide insight into the relationship between CMV and AL and provide awareness of factors that affect their relationship.

Sources of Lead Exposure in West Africa

This commentary is an investigation of sources of lead (Pb) exposure in West Africa. Pb is generally acknowledged as one of the most widespread environmental health hazards in West Africa, and there is heightened concern over adverse health effects at various levels of exposure (at doses once considered safe) in the West African region. A literature review for the possible health implications of Pb exposure on human health showed nervous system dysfunction, anemia, and potential cognitive diseases as the major health issues among children, while adults were found to suffer more from cardiovascular dysfunction, neurological decline, and reproductive diseases. Despite a decline in blood lead levels (BLLs), lead exposure continues to be a major public health concern as no level of Pb exposure can be considered safe. Moreover, lowering BLLs entails identifying various lead sources such as gasoline emissions, leaded paint, canned foods, and beverages, as well as plausible biological pathways of lead exposure and response. However, only countries such as Nigeria and Ghana have extensive research available regarding the different sources of Pb exposure. Further, it is not apparent which country is affected the most by Pb exposure. Therefore, this commentary was aimed to explore different literature sources to describe and list the different sources of Pb exposure in 15 West African countries. The findings indicated water, food, and occupational exposure as the major sources of Pb exposure in the region. People with occupations such as e-waste and Pb acid battery recycling, auto mechanics, fuel attending, welding, electronic repairing, farming/spraying, and mining were found to be at immediate risk. Tobacco, spices and paints constituted additional potential sources of exposure. For residents living near landfills or urban area, the major sources of Pb exposure were soil, air, and dust particles. The review revealed a vast research gap on the sources and implications of Pb exposure. Exposure to Pb could further increase due to uncontrolled traffic, urban growth, inadequate urban planning, and the inadequate enforcement of regulations. Therefore, more extensive research on the changing trends of Pb exposure among West African populations is needed.

The Association between Multiple Per- and Polyfluoroalkyl Substances' Serum Levels and Allostatic Load

Background/Objective: This study aimed to explore the association between allostatic load (AL), an index of chronic stress, with nine per- and polyfluoroalkyl substances (PFASs), a group of organic compounds used in commercial and industrial applications. The PFASs explored were perfluorohexane sulfonic acid (PFHS), perfluorodecanoic acid (PFDE), perfluorobutane sulfonic acid (PFBS), perfluoroheptanoic acid (PFHP), perflurododecanoic acid (PFDO), perfluorononanoic acid (PFNA), perfluoroundecanoic acid (PFUA), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonic acid (PFOS). This study was performed to better understand the association between PFASs and AL, which may be a mediator of several diseases. Methods: This study was performed on adults aged 20 and older, using the National Health and Nutrition Examination Survey (NHANES) 2007−2014 data. AL was calculated as a cumulative index of ten biomarkers from the cardiovascular, inflammatory, and metabolic system, which was dichotomized into high risk (assigned a value of 1) or low risk (assigned a value 0) depending on if the index value was ≥3 (chronic physiological stress) or <3 (less stressed). In this study, PFASs and covariates such as age, gender, ethnicity, alcohol consumption, smoking, and physical activity were explored using descriptive statistics and logistic regression modeling. Results: The results indicated that in adults, AL was more elevated in men as compared to women, in those aged ≥60 years, and varied by ethnicity. For instance, non-Hispanic Blacks had higher AL levels (mean of 3.92) compared to other ethnicities. A significant number of the participants tested for PFBS, PFHP, PFDO were below the LOD and thus these PFASs were excluded from the analysis. Our analysis demonstrated multicollinearities between variables such as PFNA, PFOS, and PFOA with variance inflation factor (VIF) values of 6.197, 6.212, and 5.139, respectively. Thus, PFASs were analyzed individually and adjusted for age, gender, ethnicity, physical activity, smoking, and alcohol consumption. The results indicated a statistically significant positive association between AL and most of the PFASs, except PFUA which was not statistically significant with a p value of 0.531. Conclusions: The findings of this study suggest that exposure to PFDE, PFNA, PFOS, PFOA, and PFHS are associated with AL when adjusted for age, gender, ethnicity, alcohol consumption, smoking, and physical activity. Future studies looking to model the effects of these factors together must consider their relationship with each other and choose different analytical approaches.

Interaction of Per- and Polyfluoroalkyl Substances and Allostatic Load among Adults in Various Occupations

Objective: This study sought to assess the associations between occupation, serum concentrations of selected of Per- and Polyfluoroalkyl Substances (PFAS), and chronic physiological stress, as operationalized by Allostatic Load (AL), among adults aged ≥20 years. Methods: To explore the interactions of occupation with PFAS levels and AL, data from the National Health and Nutrition Examination Survey (NHANES) 2007−2014 were used. We performed Poisson regression modeling to evaluate AL’s relationships with PFAS concentrations and occupations on weighted data. Results: The results demonstrated that increased AL was positively associated with different occupation groups such as a) Public Administration and b) Arts, Entertainment, and Recreation (p-values 0.018 and 0.002, respectively), and with certain PFAS concentrations (Perfluorooctanoic acid, PFOA, p-value = 0.002). Finally, AL had a strong association with the interaction of some PFAS such as Perfluorobutane sulfonic acid (PFBS) and occupation (AL: PFBS: occupation, p-value < 0.0001), with different association measures existing across varying occupations. Conclusions: Occupation and PFOA seem to be associated with AL. This suggests the need of implementing further strategies to limit the exposure to stressors and PFAS in the work environment to promote longevity among the workforce in the U.S. Finally, policymakers must do more to clearly define standards and regulations in the work environment related to PFAS exposure.

Blood lead, nutrient intake, and renal function among type 2 diabetic patients

Lead (Pb) exposure has been reported to have nephrotoxicity. However, such an effect has not been well investigated in type 2 diabetes (T2D) patients, especially when taking into account the nutrition status of the patients. Therefore, we explore the association between blood lead levels (BLLs), dietary intake of nutrients, and impaired renal function among patients with T2D. We measured BLLs and biochemical parameters of renal injury in 780 patients. Dietary nutrients intake was assessed by a food frequency questionnaire in 420 of 780 participants. We found high BLLs were significantly associated with certain parameters of renal injury, and dietary intake of specific nutrients (mainly micronutrients) was associated with reduced BLLs at high percentile distribution of concentration. BLLs were also found to have moderation effects on the association between specific dietary nutrients and specific renal function parameters.

Interaction of Smoking and Lead Exposure among Carriers of Genetic Variants Associated with a Higher Level of Oxidative Stress Indicators

Smoking and lead (Pb) exposure increased oxidative stress in human body, and people with some gene variants may be susceptible to Pb and smoking via oxidative stress. The aim of this study is to evaluate oxidative stress by measuring thiobarbituric acid reactive substances (TBARS) and the relationship of lipid peroxidation markers in Pb workers with different gene polymorphisms (rs4673 and rs1050450) in both smokers and nonsmokers. Blood samples were collected from 267 Pb workers who received their annual health examination in the Kaohsiung Medical University Hospital. Glutathione peroxidase 1 (GPx-1) rs1050450 and cytochrome B-245 Alpha Chain (CYBA) rs4673 single-nucleotide polymorphisms (SNP) were analyzed by specific primer-probes using Real-Time PCR methods. The interaction between blood Pb and smoking increased serum levels of TBARS and the ratio of oxidative low-density lipoprotein and low-density lipoprotein (oxLDL/LDL). Analysis of workers with rs1050450 SNPs showed higher blood Pb levels in the workers with CC genotype than those with CT genotype. Smokers had significantly higher blood Pb, alanine transaminase (ALT), TBARS, and OxLDL levels than nonsmokers. TBARS increased 0.009 nmol/mL when blood Pb increased one µg/dL in smokers compared to nonsmokers. The ratio of OxLDL/LDL increased 0.223 when blood Pb increased one µg/dL in smokers compared to nonsmokers. TBARS levels and the ratio of OxLDL/LDL were positively correlated and interacted between blood Pb and smoking after the adjustment of confounders, suggesting that smoking cessation is an important issue in the Pb-exposed working environment.

Combined Effect of Lead Exposure and Allostatic Load on Cardiovascular Disease Mortality-A Preliminary Study

This study explores the combined effect of lead (Pb) exposure and an index of chronic physiological stress on cardiovascular disease mortality using data from the National Health and Nutrition Examination Survey (NHANES) 1999-2008 linked to 1999-2014 National Death Index data. Chronic physiological stress was measured using the allostatic load (AL) index, which was formed by analyzing markers from the cardiovascular, inflammatory, and metabolic systems, with Pb levels, assessed using blood lead levels (BLL). The dataset was analyzed with statistical techniques to explore (a) the relationship between Pb exposure and AL, and (b) the combined role of Pb and AL on cardiovascular disease mortality. Results indicated that AL was more elevated in those with BLLs above the 50th percentile in the US population and that those with elevated AL were more likely to have high BLL. Finally, the interaction of AL and BLL significantly increased the likelihood of cardiovascular disease mortality. These findings highlight the need for considering the totality of exposures experienced by populations to build holistic programs to prevent Pb exposure and reduce stressors to promote optimal health outcomes and reduce cardiovascular mortality risk.

Cumulative Effects of Low-Level Lead Exposure and Chronic Physiological Stress on Hepatic Dysfunction-A Preliminary Study

Chronic physiological stress and hepatic injury were explored in this cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) 2007–2010. Lead exposure was measured using Blood Lead Levels (BLL), which were divided into quartiles of exposure based on the distribution within the database. Allostatic load (AL), a variable representing chronic physiological stress, was operationalized using ten clinical markers. The geometric mean values for markers of liver injury of interest (a) Aspartate Aminotransferase (AST), (b) Alanine Aminotransferase (ALT), (c) Alkaline Phosphatase (ALP), and (d) Gamma glutamyl-transferase (GGT) were explored in quartiles of lead exposure. Associations between AL and AST, ALT, ALP, and GGT among those exposed to lead were analyzed using linear regression models. In examining lead exposure in increasing quartiles, the geometric mean of the liver injury markers showed significant elevations as lead exposure levels increased. Simple linear regression revealed AL was positively associated with several markers of hepatic injury in all degrees of lead exposure. This study demonstrates the potential dangers of social and environmental exposures to liver health.

Influence of Prenatal Exposure to Mercury, Perceived Stress, and Depression on Birth Outcomes in Suriname: Results from the MeKiTamara Study

Prenatal exposure to mercury, stress, and depression may have adverse effects on birth outcomes. Little is known on the influence of chemical and non-chemical stressors on birth outcomes in the country of Suriname. We assessed the influence of prenatal exposure to mercury, perceived stress, and depression on adverse birth outcomes in 1143 pregnant Surinamese women who participated in the Caribbean Consortium for Research in Environmental and Occupational Health-MeKiTamara prospective cohort study. Associations between mercury (≥1.1 μg/g hair, USEPA action level/top versus bottom quartile), probable depression (Edinburgh Depression Scale ≥12), high perceived stress (Cohen's Perceived Stress Scale ≥20), and adverse birth outcomes (low birthweight (<2500 g), preterm birth (<37 completed weeks of gestation), and low Apgar score (<7 at 5 min)) were assessed using bivariate and multivariate logistic regressions. Prevalence of elevated mercury levels, high perceived stress, and probable depression were 37.5%, 27.2%, and 22.4%, respectively. Mercury exposure was significantly associated with preterm birth in the overall study cohort (OR 2.47; 95% CI 1.05-5.83) and perceived stress with a low Apgar score (OR 9.73; 95% CI 2.03-46.70). Depression was not associated with any birth outcomes. These findings can inform policy- and practice-oriented solutions to improve maternal and child health in Suriname.