Hydrogen cyanide and carbon monoxide in blood of convicted dead in a polyurethane combustion: a proposition for the data analysis

Carbon monoxide is a well-known toxic component in fire atmospheres. Howeve r, the importance of hydrogen cyanide as a toxic agent in fire causalities is under discussion. A tragic polyurethane mattress fire provoked death of 35 convicts in a prison (Unit I, Olmos, Penitenciary Service of Buenos Aire s Province, Argentina), in 1990. There is no report of any investigation ca rried out with such a large amount of victims in Argentina. Carboxihemoglob in (COHb) and hydrogen cyanide (HCN) were quantified in victims blood to el ucidate the cause of the death. Saturation of COHb ranged between 4 and 18% , and HCN 2.0-7.2 mg/l. These latter values were higher than the lethal lev els reported in literature. Other toxic components routinely measured (etha nol, methanol, aldehydes and other volatile Compounds) gave negative result s on the 35 cases. Neither drugs of abuse nor psychotropics were detected. Statistical chi (2) analysis was applied to find differences between HCN an d COHb concentrations. Saturation of COHb and HCN in blood were not indepen dent variables (chi (2) = 8.25). Moreover, the ratio COHb/HCN was constant (0.47 +/- 0.04). In order to evaluate the contribution of each toxic to the diagnosis, a lethal index was defined for each toxic (LICO and LIHCN). The most probable cause of death could be inferred by a suitable plot of both indexes. The results indicated that death in the 35 fire victims was probab ly caused by HCN, generated during the extensive polyurethane decomposition provoked by a rapid increase of temperature. (C) 2001 Elsevier Science Ire land Ltd. All rights reserved.