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Item #9

Lead Levels Linked to Hypertension

Lead at levels far below those considered safe can increase blood pressure.

That, according to the results of a study of perimenopausal women published in the March 26 issue of The Journal of the American Medical Association.

"Blood lead is among the few predictors of both systolic and diastolic blood pressures in perimenopausal US women. Per unit change, blood lead was a stronger predictor of diastolic blood pressure than age," write Denis Nash, PhD, MPH, from the University of Maryland School of Medicine in Baltimore, and colleagues. "From a public health perspective, the most important and troubling implication of these findings is that lead appears to increase blood pressure in women at very small increments above 1.0 µg/dL, well below what is considered deleterious in adults."

Dr. Nash's group conducted a household interview and physical examination of 2,165 women, aged 40 to 59 years, who participated in the Third National Health and Nutrition Examination Survey from 1988 to 1994.

After adjustments for age, race, ethnicity, alcohol intake, cigarette smoking, body mass index, and kidney function, blood lead levels were significantly associated with prevalence of systolic and diastolic hypertension. Compared with women in the lowest blood lead quartile (mean, 1.0 µg/dL), women in the highest quartile of blood lead (mean, 6.3 µg/dL) had a 3.4-fold increase in the risks of diastolic hypertension (adjusted odds ratio [OR] 3.4; 95% confidence interval [CI], 1.3 - 8.7).

The effect of lead level on risk of diastolic hypertension was even higher in postmenopausal women (OR for highest to lowest quartile, 8.1; 95% CI, 2.6 - 24.7). Blood lead levels were also linked to moderately increased risks of general and systolic hypertension.

Compared with women in the lowest quartile of blood lead levels, those in the highest quartile had a difference in mean blood pressure of 1.7 mm Hg systolic and 1.4 mm Hg diastolic. Mean blood lead level in this sample was 2.9 µg/dL. These findings suggest effects of lead at levels less than the U.S. occupational blood lead exposure limits (40 µg/dL) and even less than the current Centers for Disease Control and Prevention level for preventing lead poisoning in children (10 µg/dL).

"The findings from our study of associations of blood lead with systolic and diastolic hypertension and blood pressure among women in the general population lend support for further studies on the health effects of bone lead mobilization during the menopausal transition," the authors write. "These results provide support for continued efforts to reduce lead levels in the general population, especially women."

JAMA. 2003;289:1523-1532

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