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

Abstract

Chronic stress and cardiovascular disease risk were explored in a predominately middle-aged adult population exposed to elevated lead levels in this cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) from the period 2007-2010. Elevated lead exposure was defined using the epidemiological threshold of a blood lead level (BLL) > 5 μg/dL as defined by the U.S. Centers for Disease Control and Prevention (CDC). Allostatic load (AL), a measure of chronic stress, was operationalized using 10 clinical markers. The geometric mean values for clinical cardiovascular disease risk markers of interest (a) Gamma glutamyl-transferase (GGT) (a marker of oxidative stress), and (b) non-HDL cholesterol (non-HDL-c) (a marker of cardiovascular disease risk) were explored among lead-exposed and less lead-exposed individuals with differential chronic stress (AL) levels. Associations between AL and GGT/non-HDL-C were analyzed using linear regression models. The likelihood of increased clinical markers in lead-exposed individuals with high compared to low AL was explored using binary logistic regression models. In analyzing lead-exposed as compared to less lead-exposed populations, the geometric mean of the variables of interest showed significant elevations among lead-exposed individuals as compared to less lead-exposed individuals. Simple linear regression revealed that AL was positively associated with the variables of interest among the lead-exposed. In binary logistic regression among the lead-exposed, those with high AL, as compared to those with low AL, had significantly higher odds of having elevated non-HDL-C. This study submits that those exposed to lead with increasing AL may experience adverse cardiovascular health outcomes.

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

“…Each individual in the study was assigned a value of 1 if they are in the high-risk category or a 0 if in the low-risk category for all markers to calculate a total AL value out of 10. Clinical and laboratory collection and analysis of markers and variables of interest have been described elsewhere [ 35 , 43 ].…”

“…Technical details of the survey, including sampling design, data collection protocols, and data availability, are freely available on their website. Data collection for NHANES makers of interest have been described elsewhere [ 35 ]. This study used de-identified secondary data; hence, the study did not require IRB approval.…”

“…Prior studies by the lead author have demonstrated potential associations between AL and cardiovascular dysfunction among those exposed to differing concentrations of Pb, but more information is needed to understand how the combination of Pb and AL contributes to cardiovascular disease mortality [ 35 ].…”

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

“…Exposure to distress can come from several sources such as occupation, family life, emotional problems, and can alter the health of various populations [ 38 , 39 , 40 ]. When combined with the exposure to lead via water, air, soil, dust, and food [ 41 , 42 , 43 ], the damage to the health of populations may suffer a combined or synergistic effect [ 16 , 26 , 44 , 45 , 46 , 47 ].…”

“…Based on prior studies [ 25 , 26 ], AL was operationalized via a cumulative index of dysfunction across multiple physiological systems such as the cardiovascular system (Systolic Blood Pressure—SBP, Diastolic Blood pressure—DBP, triglycerides, High Density Lipoprotein—HDL cholesterol, total cholesterol); the inflammatory system (C-reactive Protein—CRP for systemic inflammation); and finally the metabolic system (Albumin, Body Mass Index—BMI, hemoglobin A1C, and Creatinine Clearance). These markers were divided into quartiles based on their distribution within the database with high-risk for each biomarker considered the top quarter in the distribution for all markers apart from the markers for albumin, creatinine clearance, and for HDL cholesterol, for which the lowest quarter of the distribution was the highest risk [ 8 , 27 , 28 , 29 , 30 , 31 , 32 ].…”