Forensic Science International 43 (198919- 14 Elsevier Scientific Publishers Ireland Ltd.

THE ROLE OF HYDROGEN CYANIDE AND CARBON MONOXIDE IN FIRE CASUALTIES: A PROSPECTIVE STUDY

PER LUNDQUIST’, LENNART RAMMERb and BO SORB@

Deportments of Win&xl Chemistry and bForensic Medicine, Faculty of Health Sciences, Univer- sity of Link@ing, S-581 85 Linkiiping (Sweden)

(Received March 28th, 19881 (Revision received November 28th. 19881 (Accepted December 22ndJ9881

Determinations of blood cyanide and carboxyhemoglobin concentrations were performed in 18 victims found dead in buildings after fires during a 2-year period. The results indicated that 59% of the victims had been exposed to toxic levels of hydrogen cyanide and 99% to toxic levels of carbon monoxide. Lethal concentrations of carbon monoxide were found in 83% of the victims. In one case a lethal blood cyanide but a non-toxic blood carboxyhemoglobin value was found. It is concluded that carbon monoxide appears to be more important than hydrogen cyanide as a toxic agent in the fire atmosphere, but cyanide poisoning without carbon monoxide poisoning may, under certain circumstances, be the cause of death in fire victims.

Key words: Hydrogen cyanide; Carbon monoxide; Fire deaths; Autopsy

Introduction

Fire fatalities may be due to burn injuries, smoke inhalation or a combination of both [1,2]. A well-known toxic component in the fire atmosphere is carbon monoxide but hydrogen cyanide has also attracted attention in this respect [3,4]. The occurrence of cyanide in the blood of fire casualties as first reported by Wetherell[5] and a number of other reports have confirmed these findings. Hydrogen cyanide is produced in fires by pyrolysis of nitrogen-containing organic material such as wool or certain plastics [6,7]. The importance of hydro- gen cyanide as a toxic agent in fire casualties is however under debate. Some authors thus report that cyanide poisoning may be an important cause of fire deaths [8-151. Others, however, consider carbon monoxide to be the major toxic agent in fires and consider hydrogen cyanide to be of little or no importance in this respect [16-181. These opinions are mainly based on the results of determinations of carboxyhemoglobin and cyanide in the postmortem blood from fire victims. As no such studies have up till now been reported from Scandinavia, the present paper presents such a study.

0379-0738189/$03.50 0 1989 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland

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Materials and Methods

Initially this study comprised 20 consecutive victims found dead after fire in buildings during the 2-year period January 1985 to January 1987 and subjected to postmortem examination at the State Institute of Forensic Medicine in Linkiiping, Sweden. Two cases had later to be excluded, however, due to technical errors in the analysis of cyanide, leaving 18 cases. Burns were graded as + = partial, + + = total body area with second and third degree burns, + + + = severe charring. During autopsy femoral venous blood was collected in an acid silver sulfate solution for determination of cyanide according to Lundquist et al. [19]. As the reference values reported by these authors were, obtained from healthy living subjects, blood cyanide was also determined in ten control autopsy cases giving as a result 0.24 f 0.21 pmol/l (mean r S.Dl and an upper reference limit of 0.66 pmol/l (1 pmol/l = 0.026 mg/l). Femoral venous blood was also used for determination of carboxyhemoglobin [20] and ethanol [21].

TABLE 1

POSTMORTEM FINDINGS IN FIRE VICTIMS 1985- 1986

Case Age no. /years/

Sex BU77hS Tracheal B-Ethanol B-Cyanide soot Wool lwwU

B-COHb 1%)

1 71 M 2 61 M 3 74 M 4 57 M 5 40 M 6 61 M 7 65 F 3 50 M 9 56 M

10 34 F 11 76 F 12 77 M 13 14 F 14 32 M 15 60 F

16 55 M 17 84 F 18 49 M

+ +++ +++

+ +

+++ +++ +++ +++

++ +++ +++ +++ +++

++ +++

+ + + + + +

+ + +

+ + + + + + +

0 3.4 65 2.4 1.2 70 2.6 37.1 59 3.2 57.5 70 4.2 42.0 70 1.4 53.0 53 2.6 101.0 5 2.4 15.1 70 1.7 28.9 70 2.1 56.8 60 0 50.0 54 0 19.1 28 ND 42.8 70 0 0.6 3 0 1.0 50 0 55.0 63 0 11.5 70 3.4 53.0 70

ND = Not determined. B-Ethanol %IO = g/l.

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Results

As shown in Table 1, ten of the 17 victims investigated with respect to blood ethanol had detectable levels of this compound, often in fairly high concentra- tions. This is in confirmation of the well-known fact that ethanol intoxication is an important predisposing factor in fire deaths [22]. Only one of the victims (case 14) had a blood cyanide concentration lower than the upper reference limit of the control autopsy material. The carboxyhemoglobin concentration in this subject was also normal, suggesting little or no inhalation of the fire atmosphere although a presence of tracheal soot was noted at autopsy. Among the 18 cases investigated nine had blood cyanide concentrations above 40 pmol/ 1, which is considered as a possibly toxic concentration [4]. One of these victims (case 7) had a blood cyanide value of 101 pmol/l, which is a probably lethal concentration [4,9,12,15,16]. This case was a female alcoholic found dead in her bed, the fire probably being caused by smoking. Her blood carboxyhemoglobin was only 5%, which is a non-toxic concentration. Cyanide in the gastric content was not demonstrated and no tracheal soot was found. The cyanide in blood may have been caused by slow pyrolysis of the plastic mattress before formation of carboxyhemoglobin occurred. Sixteen of 18 victims had blood car- boxyhemoglobin above 200/b which is a level where toxic symptoms appear [23], and 15 of these had carboxyhemoglobin above 50%, which is the accepted fatal concentration [2,22]. There was no correlation between carboxyhemoglobin and cyanide in the blood from the victims (Fig. 1).

Discussion

The results of the present investigation demonstrate that fire victims are often exposed to hydrogen cyanide in the fire atmosphere as raised levels of

loo- ??

Ot- 0

_ ._ 7

50 100 B-COHb (%I

Fig. 1. Correlation between B-Cyanide and B-COHb concentrations.

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TABLE 2

CYANIDE AND CARBOXYHEMOGLOBIN IN BLOOD FROM FIRE VICTIMS, % CASES WITH TOXIC AND LETHAL CONCENTRATIONS

Area studied. Cyanide Garboxyhemoglobin

>40 pmoUP > 100 pnol/P > 2.0%” > 50%’

Glasgow [9] 32 6 81 51 Glasgow [12,24] 39 12 78 53 Newark, N.Y. [22] 19 0 95 64 Linkiipingd 56 6 89 83

‘References given within brackets. Toxic concentration (4,231. ‘Fatal concentration [2,4,15,22]. *Present study.

blood cyanide were detected in 17 of 18 cases. Only nine of these cases (50°~l however, had blood cyanide levels considered to be toxic and eight of these victims had fatal carboxyhemoglobin levels. Thus carbon monoxide poisoning appears to be a more important cause of fire deaths than cyanide poisoning.

As is evident from Table 2, the results of the present study with respect to blood cyanide level are similar to those obtained by Anderson et al. from the Glasgow area [9,12] but higher than those reported by Barillo et al. from New- ark [22]. The different results with respect to blood cyanide may be due to the fact, as pointed out by Barillo et al. [22], that the majority of victims from the Newark area came from fires in old buildings constructed before the use of plas- tic became more widespread. In Glasgow and Linkoping, however, more casualties may have occurred in modern buildings, where the fire atmosphere contained high concentrations of hydrogen cyanide from pyrolsis of nitrogen-containing plastics [6,7]. The composition of the material in the burned buildings was not possible to determine in our study.

In the Glasgow studies [9,12,24] 51 and 53% of the cases had a carboxyhemoglobin concentration below 50%, compared to 17% in our study. This may be explained by the higher age and the more common occurrence of heart disease in the Glasgow material.

It may be noted in this connection that one of the victims in the present study had a fatal blood cyanide concentration but a very low carboxyhemo- globin value, suggesting that her death was due to cyanide poisoning. The possible exposure of fire victims to cyanide should thus not be neglected. This is especially important in surviving victims, where carboxyhemoglobin and cyanide additively may interfere with the oxygen transport, and where treat- ment with oxygen and cyanide antidotes therefore may be life saving [10,25.26]. However, as cyanide antidotes are endowed with risks [26] and the symptoms of cyanide poisoning in fire casualties are vague [2,26], the detection of cyanide

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exposure by laboratory methods is of importance. Determination of carboxyhemoglobin, which is more easily performed than determination of cyanide, has been suggested for this purpose [27]. The validity of this approach requires, however, a high correlation between carboxyhemoglobin and cyanide in the blood from fire casualties, but reports on this topic are controversial. A high correlation was thus found by some investigators [4,9,16,27], whereas oth- ers report little or no correlation [13,14,18]. In the present study no correlation was found. Consequently, more rapid and convenient methods than those now available for the determination of blood cyanide should be developed.

Determination of cyanide in postmortem blood is also of diagnostic value as an indicator of intravital burning as elevated cyanide levels were found in 17 out of the 18 cases. In certain cases cyanide intoxication might also significantly contribute to the fatal outcome and in isolated cases possibly be the single cause of death.

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