Chronic Lead Exposure, Women and Hypertension
Mitch Kennedy, ND
It is common knowledge that bone turnover accelerates as women enter perimenopause and menopausal years. What is not commonly known is that this turnover also accelerates the release of heavy metals, particularly lead, stored in the bones. As lead is one of the predominant metals stored in bone, and a known causative agent for hypertension, clinicians may need to consider this as an etiology.
A 2002 study evaluated risk factors for elevated blood and bone lead levels in 264 women in Boston, Mass. Participants were 46-74 years and had mean lead levels of 3 micro g/dl (blood; standard deviation 2), 13 micro g/g (tibia, SD 9) and 17 micro g/g (patella, SD 11). In multivariate linear regression models, use of postmenopausal estrogen (inverse) and alcohol intake (positive) were significantly associated with blood lead levels. Both bone lead measures were significantly and positively associated with blood lead, but only among postmenopausal women not using estrogen. Older age and lower parity were associated with higher tibia lead; only age was associated with patella lead (Korrick et al., 2002).
A cross-sectional analysis of 2001-2002 data was performed from a community-based cohort in Baltimore, Md., of 964 men and women aged 50-70 years (40% African American, 55% White, 5% other race/ethnicity). Blood lead was a strong and consistent predictor of both systolic and diastolic blood pressure in models adjusted and not adjusted for race/ethnicity and socioeconomic status. Tibia lead was associated with hypertension status before adjustment for race/ethnicity and socioeconomic status (p = 0.01); after such adjustment, the association was borderline significant (p = 0.09). The data suggest that lead has an acute effect on blood pressure via recent dose and a chronic effect on hypertension risk via cumulative dose (Martin, 2006).
The relationship of hypertension, lead exposure and menopause is detailed in a second study by Korrick. This case-control study assessed the relationship of blood and bone lead concentrations to hypertension in women in a group of 284 cases and 405 controls, with a mean age of 58 years. The researchers found a direct correlation between increase in incidence of hypertension and increases in patella lead levels, and lead levels and age. The authors conclude there is a significant role for low-level lead exposure as a risk factor for hypertension among non-occupationally exposed women (Korrick, 1999).
Korrick SA et al: Correlates of bone and blood lead levels among middle-aged and elderly women, Am J Epidemiol Aug 15;156(4):335-43, 2002.
Martin D et al: Association of blood lead and tibia lead with blood pressure and hypertension in a community sample of older adults, Am J Epidemiol Mar 1;163(5):467-78, 2006.
Korrick SA et al: Lead and hypertension in a sample of middle-aged women, Am J Public Health Mar;89(3):330-5, 1999.
Mitch Kennedy, ND has a family practice in Avon, CT, and is the first ND with clinical privileges at the University of Connecticut, a teaching hospital. Before graduation from Southwest College, Kennedy earned an international reputation as a leader in pollution prevention, showing industries around the world how preventing pollution saves money.