- Author
- Levin, B. C. | Paabo, M. | Navarro, M.
- Title
- Toxic Interactions of Binary Mixtures of NO2 and CO, NO2, and HCN, NO2 and Reduced O2, and NO2 and CO2.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
- Abstract 825,
- Book or Conf
- Society of Toxicology. Annual Conference, 30th. Abstracts. Volume 11. Number 1. February 25-March 1, 1991, Dallas, TX, 222 p., 1991
- Keywords
- toxic gases | rats | exposure
- Abstract
- A model to predict the toxic interactions of the major gases produced in fires is being developed at NIST and includes six gases--CO, CO2, HCN, reduced O2, HC1, and HBr. The current objective is to add NO2 to the model. The toxicity of individual gases, CO, CO2, reduced O2, HCN, and NO2, in air as well as various two, three and four gas combinations have been examined in Fischer 344 male rats exposed for 30 min and observed for 14 days. LC50's for HC1 and HBr were obtained from the literature. Deaths from NO2 in air occurred only in the post-exposure (PE) period and its LC50 is 200 ppm (PE). Carbon dioxide has synergistic toxicological effects when combined with any of the other gases tested at NIST. The LC50 for NO2 in the presence of 5% CO2 is 90 ppm (PE). CO produces only within-exposure deaths (WE) and its 30 min LC50 is 6600 ppm. In the presence of 200 ppm of NO2, the WE toxicity of CO increased. At the new LC50 of CO, the PE toxicity of NO2 also increased. Deaths from HCN occur primarily during or within 24 hours following exposure and its LC50's are 200 ppm (WE) and 150 ppm (PE). An antagonistic effect is observed with NO2 and HCN; in the presence of 200 ppm of NO2, 2.3 to 2.5 times the HCN LC50 is needed to produce one death within-exposure. Deaths from reduced O2 occur primarily within exposure and its 30 min LC50 is 5.4%. In the presence of 200 ppm of NO2, the WE LC50 of O2 and its toxicity increased. At this new LC50 of O2, the PE toxicity of NO2 increased. Thus NO2, and PE toxic gas, increases the toxicity of the WE toxic gases (except HCN) and vice-versa.