Blood-lead and cadmium in human hypertension.

An epidemiological study amongst hypertensives and normotensives in Renfrew, Scotland, where drinking water hardness is very low (5 p.p.m.) and water-lead levels are commonly high, has shown a significant association between high blood-lead levels and high blood pressure. No association was found with indices of renal function, plasma renin or angiotensin II concentrations or serum uric acid levels. In a parallel study of blood-lead levels in Birmingham, England, where water hardness is low (20 p.p.m.) but water-lead levels are also low, high blood-lead levels were not found, no relationship was found with blood pressure and the prevalence of hypertension was lower than in Renfrew. We conclude that sub-clinic lead exposure from drinking water may be a factor in the development of hypertension. A study of blood-cadmium levels has shown no association between high blood pressure and sub-clinical cadmium exposure, but confirmed a close relation between blood-cadmium and cigarette smoking. We conclude that previous reports of a cadmium-blood pressure link may be confounded by failure to allow for the cigarette smoking habits of the subjects studied.