Effect of exposure to heat, hypoxia, cold, acceleration, and vibration stress on the total blood sulfhydryl groups in human subjects.

The percent utilization of total blood sulfhydryl (bl-SH) group was assessed in 100 healthy, unacclimated male Indian Air Force Personnel who participated in various stress trials which included heat, cold pressor test, hypoxia, 70 degrees head-up tilt, acceleration, and vibration. Exposure to a hot and dry environment (Tdb = 57 degrees C, rh = 25%, Oxford Index = 38.7 degrees C) for a period of 50 min showed a 49.7% fall in the total bl-SH group (p less than 0.001), while exposure to a hot and wet environment (Tdb = 50 degrees C, rh = 50%, Oxford Index = 40.7 degrees C) for a similar period showed a greater fall of 61%. Hand immersion for 2 min in water at 4 degrees C showed a 42.7% fall in the total bl-SH group (p less than 0.001). Exposure to 4572 m for 45 min showed a 36.7% fall in the same variable (p less than 0.001). Exposure to 70 degrees head-up tilt for 20 min did not produce any significant change in the bl-SH groups, whereas acceleration stress showed a highly significant fall (p less than 0.001), and low-frequency sinusoidal vibration produced a 42.7% rise.