Exposure to cadmium and conventional and ambulatory blood pressures in a prospective population study

This prospective population study investigated in a random sample of 692 subjects (age 20–83 years) how changing environmental exposure to cadmium influenced blood pressure (BP) and the incidence of hypertension. At baseline (1985 to 1989; participation rate, 78%) and follow-up (1991 to 1995; re-examination rate, 81%), blood pressure was measured by conventional sphygmomanometry (CBP; 15 readings in total) and, at follow-up, also by 24-h ambulatory blood pressure monitoring (ABP). Systolic/diastolic CBP at baseline averaged 128.4/77.3 mm Hg. At baseline, blood cadmium concentration (B-Cd) and urinary cadmium excretion (U-Cd) averaged (geometric means) 11.1 nmol/L and 10.2 nmol/24 h. Over 5.2 years (median follow-up), B-Cd fell by 29.6% and U-Cd by 15.2%. B-Cd fell less in subjects living closer to three zinc smelters and in premenopausal women. During follow-up, systolic CBP decreased by 2.2 mm Hg in men and remained unchanged in women, and diastolic CBP increased by 1.8 mm Hg in both sexes. No relationship could be demonstrated between the secular trends in CBP and B-Cd or U-Cd or between B-Cd or U-Cd at baseline and the incidence of hypertension. In addition, in cross-sectional analyses involving the average of all available CBP measurements in each participant or 24-h ABP at follow-up (mean, 119.1/71.4 mm Hg), blood pressure was not correlated with B-Cd or U-Cd. In conclusion, environmental exposure to cadmium was not associated with higher CBP or 24-h ABP or with increased risk for hypertension. The lesser fall in B-Cd in the residents living closer to the zinc smelters or in premenopausal women underscores the necessity to sanitize cadmium-polluted areas and to systematically reinforce the preventive measures to be adopted by exposed communities to reduce cadmium uptake.