Blood Lead Levels in Relation to Menopause, Smoking, and Pregnancy History

Abstract

Postmenopausal bone loss may result in the release of lead stored in bone. This study examined Mexican-American women aged 20 years and older who participated in the Hispanic Health and Nutrition Examination Survey (1982-1984) to assess the influence of menopause, pregnancy history, and smoking on blood lead levels. After adjustment for factors likely to influence blood lead levels and for design effects, the authors confirmed associations with age, income level, education, degree of urbanization, and body mass. Blood lead concentrations were markedly higher among current smokers and postmenopausal women, with these two factors showing separate, roughly additive effects. Gravidity had little impact on blood lead level among premenopausal women. However, among postmenopausal women, never-pregnant women had higher blood lead levels than did those who had ever been pregnant. The largest increase (4.4 micrograms/dl, 95 percent confidence interval 0.95, 7.8) was observed among smokers. In a separate analysis of postmenopausal women, women with recent menopause (4 years or less) had blood lead concentrations 1.4 micrograms/dl higher (95 percent confidence interval 0.20, 2.7) than did those whose menopause occurred more than 4 years previously. This finding, along with an overall slow decline in blood lead levels with each year after menopause, suggests that lead is being mobilized at rates consistent with the patterns of bone loss, placing women with recent menopause at increased risk for higher blood lead levels.