Effects of hydrogen chloride on respiratory response and pulmonary function of the baboon

The effects of hydrogen chloride (HCI) inhalation on respiratory response during exposure and on pulmonary function during the 3 mo following exposure were studied in the baboon. Each of 4 groups of three anesthetized animals was exposed in a head-only mode for 15 min to air or one of three HCI concentrations (500, 5000, or 10,000 ppm). The acute respiratory response consisted of a concentration-related increase in frequency and minute volume, with a marked decrease in blood PaO2 at the two highest concentrations. The exposures did not cause significant alterations in any of the pulmonary function parameters measured at 3 d and 3 mo postexposure. Thus, nonhuman primates were able to survive short exposures to high concentrations of HCI without any significant effects on pulmonary function during the 3 mo after exposure. Furthermore, comparison of the response of primates and rodents suggests that the human is much less sensitive to the effects of HCI than the mouse.