Forensic Science International, 52 (1991) 13- 20 13 Elsevier Scientific Publishers Ireland Ltd.

A STUDY ON HOUSE FIRE VICTIMS: AGE, CARBOXYHEMOGLOBIN, HYDROGEN CYANIDE AND HEMOLYSIS

M. YOSHIDA a, J. ADACHI b, T. WATABIKI a, Y. TATSUNO b and N. ISHIDA ~

aDepartment of Legal Medicine, Kansai Medical University, Moriguchi, 570 and bDepartment of Legal Medicine, Kobe University School of Medicine, Kobe, 650 (Japan)

(Received January 28th, 1991) (Revision received August 24th, 1991) (Accepted September 18th, 1991)

Summary

Correlation among age, concentrations of carboxyhemoglobin and hydrogen cyanide, oxygen den- sity and hemolysis were studied in 120 house fire victims. Victims aged over 60 years comprised ap- proximately 50% of the pooled subjects. Blood samples were mainly collected from the left ventricle, but sometimes from both the right and left ventricles. The concentration of carboxyhemoglobin rang- ed from 1-95%, of which 71 persons (59.7%) died with carboxyhemoglobin concentrations below 60%. Carboxyhemoglobin concentrations below 10% were found in 9 persons (7.5%). Most of these cases involved the elderly persons. In this paper, we report on the death of elderly victims as a result of low carboxyhemoglobin concentrations. A significant correlation of blood carboxyhemoglobin con- centrations existed between the right and left ventricles. The concentration of carboxyhemoglobin in the left ventricle was significantly higher than that in the right. Two out of 31 victims whose hydrogen cyanide concentrations were determined, succumbed to hydrogen cyanide poisoning, hav- ing a high concentration of hydrogen cyanide and a low concentration of carboxyhemoglobin. On analysis, oxygen density was found to be low in 13 persons. A negative correlation was shown be- tween carboxyhemoglobin concentration and hemolysis. Inasmuch as hemolysis may indicate the ex- tent of heat dissociation, hemolysis should provide an index of carbon monoxide dissociation from carboxyhemoglobin. In the present study of victims, possible causes of death i.e.,carbon monoxide gas poisoning, hydrogen cyanide poisoning, oxygen deprivation, burning, shock due to burns and others were estimated. The survival time for elderly victims was considered to be short.

Key words: House fire; Death in fire; Carboxyhemoglobin; Hydrogen cyanide; Oxygen; Hemolysis

Introduction

The causes of death in conflagration have been generally attributed to carbon monoxide poisoning and oxygen deprivation. However, with the advent of syn- thetic materials used in building constructions, one should also consider other poisonous gases (hydrogen cyanide, hydrochloric acid, ammonia, chlorine, etc.) which are released in the process. Although a few researchers have demon- strated poisoning due to these gases, their combustion products however, have not been considered to be possible contributing factors [1- 7]. Furthermore, a survey of the age range of house fire victims has not yet been investigated.

0379-0738/91/$03.50 © 1991 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland

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In the present study, we examined carboxyhemoglobin and hydrogen cyanide concentrations, oxygen density and hemolysis in postmortem blood samples ob- tained from house fire victims in the cities of Moriguchi and Kobe.

Materials and Methods

Blood samples from the right and left heart ventricles were obtained at autop- sy in Kansai Medical University and Kobe University School of Medicine within 24 h after death from 120 subjects (Age 2 - 9 0 years, male (n = 72; 61.5%), female (n = 45; 38.5%) and unknown (n = 3)) who had been victims of house fire. Carbon particles were detected within the trachea and the bronchial tubes in all cases. Each blood sample collected was stored at 4°C until further analysis.

The concentration of carboxyhemoglobin was determined for all cases by using gas chromatography [8] (until 1987) and spectrophotometry [9] (since 1987). The concentration of hydrogen cyanide in the blood was measured by flame ther- mionic detector gas chromatography [7] in 31 cases. Blood oxygen level in 18 cases was determined by the electrode method [10]. Hemoglobin concentrations in 14 cases and the ratio of hemolysis in 16 cases were determined by the cyane methemoglobin method [11].

To investigate the fatal level of hydrogen cyanide in blood, 14 mice were separately exposed to 0.5% hydrogen cyanide gas in a desiccator. After death, blood was collected from the heart and the concentration of hydrogen cyanide was determined.

Results

Age The ages of the 120 fire victims pooled for this study are presented in Fig. 1.

They ranged from 2 - 9 0 years, with a mean ± S.D. of 53.1 ± 25.2 years. The percentage of subjects belonging to the 60-year-old and above age bracket was 47.8% (n = 55).

Carboxyhemoglobin concentration The concentrations of carboxyhemoglobin are presented in Fig. 2. A large

variation in carboxyhemoglobin concentration was noted. The peak number of victims was shown in the concentration range 50 - 60%. Forty-nine cases (40.8%) had carboxyhemoglobin concentrations over 60% and 71 persons (59.2%) died with carboxyhemoglobin concentrations under 60%. On the other hand, 9 per- sons (7.5%) died with carboxyhemoglobin concentrations under 10%.

Correlation of carboxyhemoglobin concentration with other measured values The relationship between carboxyhemoglobin concentration and age is shown

in Fig. 3. No significant correlation was recognized between these two parameters. Only one victim was under 30 years of age and had a carboxy- hemoglobin concentration under 30%. This was taken to mean that younger persons were less susceptible to deaths due to low carboxyhemoglobin concentra- tions, while, it was shown that older persons were at greater risks.

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of CO-Hb ( % ) Fig. 1. Age distribution in 120 fire victims.

Fig. 2. Distribution of carboxyhemoglobin concentrat ions in 120 fire victims. hemoglobin.

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Fig. 3. (a) Relationship between carboxyhemoglobin concentrat ion and age (y = - 0.19x + 63.0, r = - 0.1746, n = 115). (b) Concentrat ion of carboxyhemoglobin in respective age groups.

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The relationship between carboxyhemoglobin and cyanide concentrations is demonstrated in Fig. 4. A low coefficient of correlation at 0.354 was noted. Two out of six persons having a hydrogen cyanide concentration of over 40 ~M were considered to have died due to cyanide poisoning, since the value of carboxy- hemoglobin concentrations in these two cases were low.

The relationship between carboxyhemoglobin and oxygen concentrations is shown in Fig. 5. Carboxyhemoglobin concentrations detected were from 1 - 95°/% whereas oxygen concentrations were below 30 mmHg, which fell within the oxygen deprivation value. When carboxyhemoglobin concentration was low enough, it was reasonable to consider oxygen deprivation as the main cause of death.

A significantly negative correlation was observed between carboxyhemoglobin concentrations and hemolysis ratio (r = - 0.712), as presented in Fig. 6.

Finally, no significant difference in each measurement value was found be- tween both sexes.

Correlation of measured value of left with right ventricle blood The relationship of blood carboxyhemoglobin concentrations between the left

and right ventricles is presented in Fig. 7. Carboxyhemoglobin concentration from the right and left ventricles was significantly correlated (r = 0.922), having a regression equation of y = 1.1x + 1.12. The value for the left ventricle was slightly higher than the value for the right ventricle.

The comparison of blood hydrogen cyanide concentrations in the right and left ventricles is displayed in Fig. 8. The coefficient of correlation (r = 0.754) was lower than that for carboxyhemoglobin concentrations (r = 0.922). The concen- tration of hydrogen cyanide in the left ventricle was also higher than that in the right one.

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Fig. 4. Relationship between carboxyhemoglobin and hydrogen cyanide concentrations (y = 0 . 3 6 x

+ 9 .8 , r = 0 . 3 3 2 , n = 32). H C N , hydrogen cyanide.

Fig. 5. Relationship between carboxyhemoglobin and oxygen concentrations (y = 0 . 0 4 3 x + 11 .9 ,

r = 0 . 1 1 5 3 , n = 19).

17

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Fig. 6. Relationship between carboxyhemoglobin concentration and hemolysis (y = - 0.71x + 67.3, r = - 0.7115 , n = 10). Hemolysis : (concentration of hemoglobin in serum / concentration of hemoglobin in blood) × 100.

Fig. 7. Relationship of blood carboxyhemoglobin concentrations between the right and left ventricles (y = 1.10x + 1.12, r = 0.9215, n = 49).

Exposure to hydrogen cyanide After exposure to hydrogen cyanide gas, the mice died in a period from

1.5-2.17 rain. The concentrations of hydrogen cyanide in the blood were 42.5 ± 11.9 t~M.

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Fig. 8. Relationship of blood hydrogen cyanide concentrations between the right and left ventricles (y = 1.56x + 12.2, r = 0.7542, n = 11).

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Discussion

Both a spectrophotometric and gas chromatographic method have been used for the quantitative determination of carboxyhemoglobin concentrations. It has been reported [12,13] that the values obtained from the spectrophotometric method are low. However, it is important to consider the fixed trend in both con- centration and binomial distributions. In addition, attention must be paid to the methemoglobin produced and the dissociation of carbon monoxide from carboxy- hemoglobin by heating. Calculation of carboxyhemoglobin concentration is based on the assumption of the standard containing 100% of the hemoglobin as carbox- yhemoglobin. This will not be the case when the other heme pigments, such as methemoglobin, are present. The existence of another form of hemoglobin will result in a higher calculated value. It has been reported that carbon monoxide dissociates from carboxyhemoglobin by heat [14-18]. In the present study, dis- sociation is estimated by the degree of burn and hemolysis. The degree of carbon monoxide dissociation is not presented in terms of numerical values. However, the degree of hemolysis displayed an extent of dissociation.

In the present study, the ratio of male to female was 6:4, in agreement with all autopsy cases performed in Kobe University School of Medicine [19]. There is a greater number of aged persons as fire victims, because the ratio of old to young victims in the present study was greater than that of the autopsy cases performed in Kobe University School of Medicine [19]. With regard to the great- er risks faced by older persons, the following factors are considered : (1) they are slower in their movement and (2) they fight a fire or protect their possessions from a fire. Teige et al. [21] reported that in carbon monoxide gas poisoning, the concentration of carboxyhemoglobin in aged victims was lower than that in younger victims. Their results were similar to the findings we have obtained from house fire victims. A likely reason is the victims' susceptibility to carbon monoxide gas.

Carboxyhemoglobin concentrations have been mainly used as an index to determine the cause of death [1,2,4,6,20-24]. A wide variation of carboxy- hemoglobin concentrations existed among the fire victims and the mean value was lower than that involving carbon monoxide gas poisoning. When the concen- tration is sufficiently high, approximately 60% and over, the cause of death is evaluated as carbon monoxide gas poisoning. If the concentration is low, the causes of death are ruled as oxygen deprivation, shock and burns. In addition, it should also be considered that combustion produces hydrogen cyanide gas [1- 7], hydrochloric acid, ammonia, chlorine, etc. It was reported that the fatal level of hydrogen cyanide poisoning in the blood was 100 uM or more, with some degree of variation. Based on the present animal experiments, the number of vic- tims having values above 40 uM was 6 out of 31. Judging from this, it can be assumed that cases of fatal hydrogen cyanide gas poisoning are rare.

The coefficient of correlation between hydrogen cyanide in the blood and car- boxyhemoglobin concentrations was low, since the ratio of carbon monoxide gas to hydrogen cyanide gas varied depending on the type of combustibles. Carbon monoxide gas is produced from the imperfect Combustion of combustibles, whereas hydrogen cyanide is produced from the combustion of chemical goods.

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In comparing blood carboxyhemogtobin concentration between the right and left ventricle, the concentration of carboxyhemoglobin from the left ventricle was 1.1 times more than from the right ventricle. This is taken to indicate that blood from the left ventricle was exposed to carbon monoxide gas until death. Hydrogen cyanide showed a similar trend.

The rationale for the negative correlation between hemolysis and carbox- yhemoglobin is due to the fact that red blood cells (RBCs) burst by heating and carboxyhemoglobin concentrations subsequently decreased by the dissociation of carbon monoxide from carboxyhemoglobin. This paper indicates that the rate of hemolysis acted as an indicator of decreased carboxyhemoglobin concentrations by heating. It is necessary therefore to investigate the hemolysis of fire victims in order to determine the dissociation of carbon monoxide.

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