Some cardiovascular effects of noise.

We recently reported that exposure to moderately high noise levels for 9 months produced sustained blood pressure elevations in rhesus monkeys (M. mulatta) without impairing their auditory sensitivity (Peterson et al, Science, 1981, 211, 143Off). In the present study, a continuation and elaboration of the earlier work, 4 chair-restrained monkeys (M. fascicularis) were studied concurrently. After 3 mo of low-noise conditions, 2 experimental Ss were exposed to a realistic noise sequence [Leq24: 85 db(A)], 24 hrs per day for about 6 mo. Compared to control animals who remained under low-noise conditions throughout the experiment, the noise-exposed Ss again exhibited a substantial increase in blood pressure, and also manifested orderly changes in the diurnal rhythm of heart rate, blood pressure, and "pauses" in cardiac rhythm. Our results conflict in detail with certain findings from earlier epidemiological studies, possibly because of differences in the species used, experimental design, or sampling strategies. The desirability of undertaking long-term prospective studies in this area is discussed.