In epidemiological studies, both positive and negative correlations have been found between cardiovascular disease and mortality and the presence of several inorganic ions in the drinking water. In an attempt to resolve this apparent disagreement, we exposed White Carneau pigeons to drinking water containing calcium (100 ppm), magnesium (30 ppm), lead (0.8 ppm), or cadmium (0.6 ppm) and used a 24-factorial design to measure the effects of these elements in atherosclerosis and hypertension. The results indicate that (i) lead and cadmium induced aortic atherosclerosis and hypertension, and (ii) calcium protects against the cardiovascular effects of cadmium. Furthermore, the effects of lead and cadmium were promoted by magnesium, and there were indications that magnesium antagonized the atherosclerotic protective effect ofcalcium. We suggest that, if these results with the pigeon can be applied to humans, the incidence of aortic atherosclerosis and hypertension should be significantly higher in areas where the drinking water contains magnesium, lead, and cadmium with a relatively low calcium concentration. Furthermore, if hard and soft water produce similar levels of lead and cadmium uptakes, the level of magnesium may be an additional factor in aortic atherosclerosis.Over the past 20 years, epidemiological and clinical evidence on the relationship between the quality of drinking water and the death rate from cardiovascular disease has been conflicting and inconclusive. Earlier studies correlated soft water with a higher cardiovascular death rate (1). Later studies showed a similar relationship but did not agree on the type of cardiovascular disease related to soft water. Various studies linked water softness to ischemic heart disease (2), to hypertension (3), to atherosclerosis (4), and to stroke (4). However, other studies do not confirm these observations (5, 6).Several specific elements in drinking water have been implicated in epidemiological studies of cardiovascular mortality.Noting that the relative concentration ofcalcium is lower in soft water than in hard water, several investigators studied the relationship between drinking-water calcium concentration and cardiovascular mortality and observed an increase in mortality when the relative concentration of calcium was lower (7). Furthermore, some studies have shown a higher incidence of cardiovascular mortality associated with consumption of soft water with relatively high concentrations of lead and cadmium (8). Again, however, other studies fail to confirm these correlations (9).The objective of the present studies was to determine the effects of calcium, magnesium, lead, and cadmium on the induction and progression of atherosclerosis and hypertension. We chose the male White Carneau pigeon (3 months ofage) for these studies because, unlike many other experimental models, it develops spontaneous atherosclerotic lesions ofboth the aorta and coronary arteries (10). METHODSMale pigeons 3 months ofage were housed indoors (in climatecontrolled, uncrowde...

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A method for extracting mercury from soil sequentially using H N 0 3 and a saturated solution of sodium sulphide (ss-Na2S) is described. Most chemical forms of mercury are soluble in HN03, with the exception of HgS. Because HgS is soluble in Na2S solution, a sequential extraction procedure was developed t o determine the distribution of HgS in soil. To determine the efficiency of this sequential extraction procedure, soil samples were spiked with either 203HgS o r 203HgCI2 and extracted sequentially with H N 0 3 and ss-Na2S. For samples spiked w i t h 203HgCI2, H N 0 3 extracted 95 and ss-Naps 1 % of the added 203HgCI2. In contrast, for soil spiked with 203HgS, H N 0 3 extracted 1 and ss-Na2S 98% of the added 203HgS. When this sequential extraction procedure was applied t o mercury-contaminated soil, the mercury concentrations in the combined H N 0 3 and ss-Na2S extracts accounted for 99% of the total mercury present. Further, of the total mercury present, 74-100% was HgS as determined b y the concentration of mercury in the ss-Na2S extract. These results suggest that the proposed sequential extraction procedure can selectively differentiate HgS from other species and compounds of mercury in soil.

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