Case reviewEffect of combined exposure to carbon monoxide and cyanides in selected forensic cases
Introduction
Toxicological tests help to identify the time span required for diagnostic procedures in forensic medical investigations of victims of fires. Toxicological examination aimed at ascertaining the dosage of carboxyhaemoglobin, cyanides and other possibly volatile products from combustion (benzene and toluene), as well as confirming its inhalation, and therefore confirming the individual's continued survival – even for a brief time – offer fundamental information in order to reconstruct the event.
This appears relevant with regard to identifying the place where the event occurred in order to exclude scenarios such as subsequent movement of the corpse, ascertaining how long the victim survived, the timeliness of help and also to the adequacy of resuscitation therapy, when administered.
Cases of death from carbon monoxide poisoning are those most frequently found both as suicides and accidental events, whilst cases of death by fire, in which hydrocyanic acid is found in the victim's blood, are rarely documented. The presence in the environment of cyanides is subordinate to the pyrolysis of organic material containing nitrogen, including synthetic polymers (polyurethane and polyacrylonitrile) and natural fiber (wool and silk), an event particularly favored in conditions of high temperature and low concentrations of oxygen.[1], [2], [3]
Blood concentrations of carboxyhaemoglobin above 50% and of cyanide above 2.7 mg/l are independently considered capable of producing a rapid lethal action.[4], [5], [6] Nonetheless it is not yet entirely clear in cases where the presence of both toxic substances has been detected, which of the two should be considered the cause of the lethal event and whether an additional, synergistic or antagonist action exists, or rather if the response induced by the two gases may be due to the sum of the effects of the single chemical components (additive effect) or if the combined effect may be greater (synergistic effect) or lesser (antagonistic effect) than that foreseen.7
Two cases are presented which are related to subjects who died as a result of exposure to fire, who were neither burned nor scalded, in which toxicological examinations provide data which helps to elucidate the kinetic action and the possible synergistic effect of the two substances (CO and HCN).
Section snippets
Case 1
A Caucasian woman, 35 years old, found dead in a composed seated position, in a train compartment, died as a result of inhaling toxic fumes which developed from a fire in the adjacent compartment. External examination revealed the presence of soot on the face and in the nostrils of the victim, with no evident signs of trauma. Internal examination revealed cherry red colouring of the organs and the presence of soot in the respiratory tracts. No anatomical abnormalities were found. The
Discussion
It is known that the toxic action of CO is in large measure due to the great affinity which it has for hemoglobin (about 200 times stronger than that for oxygen) with a consequent left-shift of the dissociation curve of the oxyhaemoglobin from which as a final result it derives an important tissue hypoxia. Some authors have moreover demonstrated, with studies carried out on both laboratory animals and subjects who died as a result of inhalation of toxic smokes from the outbreak of a fire, that
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Contribution of forensic autopsy to scene reconstruction in mass fire casualties: A case of alleged arson on a floor consisting of small compartments in a building
2015, Legal MedicineCitation Excerpt :In addition to natural, industrial and traffic disasters [1–14], there are potential dangers of mass fire disaster in densely populated areas, as well as in amusement and hotel facilities [1–11,14]. Lethal factors in indoor fires involve flames, hot gases or fumes, toxic gases including carbon monoxide (CO) and cyanide, smoke or soot, and oxygen deficiency due to combustion [14–24]. In addition, an attack of disease, or abuse of alcohol, inflammables, including thinner and gasoline, or drugs may accidentally cause a fire, and secondary traumas in a fire may be fatal [25–29].
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