"Many authorities now question the existence, or at least the clinical significance, of any inherent hypertensive effect of lead beyond that secondarily attributable to lead-associated chronic renal insufficiency." [Rosenstock, p. 583] "Acute lead intoxication is associated with hypertension, but the relationship between chronic lead exposure and hypertension remains controversial in the setting of mounting evidence." [LaDou, p. 420] "Increased blood lead levels have been associated with high blood pressure: A doubling of the lead level even within normal limits raises blood pressure 1-2 mm Hg." [APHA, p. 275] There was no consistent association between lead exposure below 30 ug/dl and increased blood pressure in the general population, giving no support for the hypothesis that "current lead exposure levels are associated with excess cardiovascular morbidity and mortality caused by hypertension." [
PMID 8622247] "In 90 to 95% of hypertensive patients, a single reversible cause of the elevated blood pressure cannot be identified, hence the term primary hypertension." Obesity and excessive consumption of salt and alcohol contribute to elevated blood pressure. Identifiable causes of hypertension include chronic kidney disease; renovascular disease, coarctation of the aorta; primary aldosteronism; Cushing's syndrome; pheochromocytoma; and obstructive sleep apnea. [Cecil, p. 375] In some groups studied but not all, individuals with higher blood levels of lead had slightly higher blood pressures. Chronic lead poisoning can cause chronic kidney disease, and chronic kidney disease can cause hypertension. See "Carbon disulfide, chronic toxic effect."