PT21 Environmental Assessment, Environmental Toxicology
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(PT298) Respiratory injury caused by brief exposure to hydrogen chloride in awake rats.

Gu, Zengfa1, Januszkiewicz, Adolph1, 1 Walter Reed Army Institute of Research, Silver Spring, MD, USA

ABSTRACT- Hydrogen chloride (HCl) gas released from burning products of polyvinyl chloride in fire environments or other explosion scenarios. The effects of HCl inhalation for short time on pulmonary function are still very unclear. This work investigated the changes of inspiratory volume (IV) resulting from exposure to different concentrations of pure HCl gas. Male Sprague-Dawley rats (250-380 grams) were randomly grouped and placed in nose-only position into restrainers connected to a polyethylene exposure chamber. At first, animals breathed with medical-grade air for five minutes. This time served as the baseline period. Subsequently, they were exposed to one of these concentrations for five minutes, afterwards, to medical-grade or ambient air. Breathing activities during the periods of baseline and exposures, and at 2- as well as 24- hr post- exposure were recorded for five minutes and analyzed using DATAQ-CODAS acquisition system. During the period of exposure to 500 ppm HCl, IV declined to 89% of its baseline. In the 1000 ppm and 2000 ppm groups, IVs dropped rapidly to 73% and 68% of their baselines respectively. At 2- hr post-exposure, IVs in all three groups recovered to close to their baselines. At 24- hr post-exposure, in 500 and 1000 ppm groups, IVs turned down to 86 and 80% of their baselines respectively. In 2000 ppm group IV dropped to 77% (p < 0.05, n=4) of its baselines. These results suggest that exposure for as short as five minutes to HCl causes immediately ventilatory disturbance and distress. A secondary respiratory injury may be induced by exposure to HCl at concentration as high as 2000 ppm.

Key words: Hydrogen Chloride, Respiratory Injury, Inspiratory Volume, Rats

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