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Lead, blood pressure, and cardiovascular disease in men and women
1U.S. Environmental Protection Agency, Office of Policy Analysis, Washington, DC 20460.
Insights
This study confirms lead exposure is linked to higher blood pressure in men and women. Reducing lead levels could significantly decrease heart attacks and cardiovascular disease incidence.
Area of Science:
- Environmental Health
- Cardiovascular Disease Epidemiology
- Toxicology
Background:
- Lead exposure is a known risk factor for elevated blood pressure, particularly in males.
- Previous studies and the Framingham study suggest a link between increased blood pressure and cardiovascular disease (CVD) risk.
- The NHANES II survey provides data for investigating environmental toxin impacts on public health.
Purpose of the Study:
- To confirm the association between lead exposure and elevated blood pressure in adult males and females.
- To investigate the relationship between lead exposure and left ventricular hypertrophy (LVH).
- To estimate the potential reduction in cardiovascular events if population lead levels are decreased.
Main Methods:
- Analysis of data from the National Health and Nutrition Examination Survey II (NHANES II).
- Statistical analysis of blood pressure and electrocardiogram (ECG) data in relation to blood lead levels.
- Utilizing logistic risk coefficients from the Framingham study to model CVD outcomes.
Main Results:
- Confirmed a significant association between lead exposure and elevated blood pressure in males (aged 20-74) and a weaker association in females.
- Demonstrated a statistically significant association between lead exposure and left ventricular hypertrophy (p < 0.01).
- Projected that halving population mean blood lead levels could prevent ~24,000 myocardial infarctions and >100,000 total cardiovascular disease events annually.
Conclusions:
- Lead exposure is independently associated with hypertension and left ventricular hypertrophy, contributing to cardiovascular disease risk.
- Reducing environmental lead exposure presents a viable public health strategy for mitigating cardiovascular disease burden.
- While the attributable risk is small relative to overall CVD incidence, it is substantial compared to other environmental toxins.
Abstract:
Lead has been shown to be associated with elevated blood pressure in males in the NHANES II survey and in numerous other studies. This study confirms the association in males aged 20 to 74 and documents a significant, although weaker, association in females as well. Prospective cardiovascular disease studies such as the Framingham study indicate that increases in blood pressure should be associated with increased risk of cardiovascular disease. Using electrocardiogram data from NHANES II, this study confirms the expected association of lead with left ventricular hypertrophy (p less than 0.01). Such an association with permanent cardiovascular changes adds weight to the blood pressure findings. The logistic risk coefficients from the Framingham study can be combined with the study's association between lead and blood pressure to examine its implication for more serious outcomes. The results suggest that a halving of the population mean blood lead level would reduce myocardial infarctions by approximately 24,000 events per year and incidence of all cardiovascular disease by over 100,000. These numbers suggest a small attributable risk compared to the vast incidence of cardiovascular disease in the U.S., but a large attributable risk compared to most environmental toxins. Several biological mechanisms have been identified, with different implications for the use of bone lead as an exposure measure.