A nine-year chronic toxicity study of cadmium in monkeys. II. Effects of dietary cadmium on circulatory function, plasma cholesterol and triglyceride.

The effects of long-term (9 y) po administration of daily low doses of cadmium on blood pressure, heart rate, electrocardiogram and plasma cholesterol and triglyceride concentrations were examined in rhesus monkeys. Thirty-five male rhesus monkeys were divided into 5 groups and fed pelleted food containing cadmium chloride at dosages of 0, 3, 10, 30 or 100 micrograms cadmium/g food (= ppm). The 100 ppm group had increased blood pressure during the initial 1 1/2 y. Thereafter, the expected increase in blood pressure that occurred due to aging in the control and 3 ppm groups was not evident in the 100 ppm group. No changes attributable to cadmium were detected in pulse rates or in electrocardiograms. Plasma cholesterol in the 2 highest dosage groups and triglyceride in the 100 ppm group were slightly lower than in controls after 2 1/2 y. Long-term exposure to cadmium contributed to the development of elevated blood pressure during the first and second years and then inhibited the hypertension expected due to aging.