Introduction
Toluene is a colorless, transparent liquid aromatic hydrocarbon with a sweet and pungent odor similar to that of benzene. It has a low flash point, making it easily flammable, and its vapor can form explosive mixtures with air, classifying it as a highly flammable substance [1]. Toluene is widely used as a solvent and thinner for paint, resin, polish, ink, adhesive, and rubber. Exposure to toluene can cause damage to the cardiovascular system, respiratory system, liver, kidneys, skin, and nervous system [2]. In particular, it exhibits hallucinogenic and inhibitory effects when inhaled, and is regulated by the Hazardous Chemical Substances Control Act to prevent abuse for hallucinogenic purposes.
During autopsies of suspected poisoning cases, it is common to collect blood, stomach contents, and urine from the bladder for toxicological testing. In this case, due to the suspicion of poisoning, in addition to the existing sample collection methods, gas was collected from the pulmonary bullae, and we report a case in which analysis of toxic substances was successfully performed. We also report the concerns regarding industrial safety.
Case Report
The deceased was a 48-year-old man, 177 cm tall and weighing 72 kg, who was performing maintenance and cleaning work in an empty liquid oil storage tank (ISO tank) with an opening diameter of approximately 50 cm (Fig. 1). He cleaned the inside of the tank using a grinder to remove residual synthetic latex foreign material. The deceased began work at 08:30 a.m. and was found unconscious around 12:16 p.m. while working alone grinding solidified latex inside a tank. He was transported to the hospital but died on the same day at 1:00 p.m.
Fig. 1.
The tank worked on by the deceased: width 6.8 m, diameter 2.4 m, capacity 24,000 L (A). The tank entrance (approximately 50 cm in diameter) through which the deceased entered for work. A cloth soaked in toluene and a nonfunctional grinder were found at the entrance (B).
When the body was discovered, a volatile odor similar to that of paint thinner remained inside the tank. About two hours after the discovery of the deceased, an analysis of the air inside the tank at the accident site revealed an oxygen concentration of 20.8% and volatile organic compounds including acetone, toluene, and benzene, at concentrations totaling 750 ppm.
The autopsy was performed within 24 hours of death, and a postmortem computed tomography (PMCT) conducted before the autopsy revealed an unruptured multicystic pulmonary bulla approximately 2.7×6.9 cm in size in the right upper lobe (Fig. 2). External examination revealed well-circumscribed erythema and ruptured blisters on the right arm, including the wrist and dorsum of the hand, right thigh, and left iliac area, measuring approximately 50×10 cm, 22×10 cm, and 10×6 cm, respectively (Fig. 3). No other injuries that could lead to death were identified except for those resulting from previous medical treatments.
Fig. 2.
Unruptured multicystic pulmonary bullae are observed in the right lung parenchyma of the deceased on postmortem computed tomography.
Fig. 3.
Well-demarcated erythema and ruptured blisters consistent with chemical burns from liquid exposure are observed.
During the internal examination, aside from the injuries caused by medical procedures such as cardiopulmonary resuscitation, no notable internal injuries were found. However, pleural adhesions and unruptured pulmonary bullae were observed in the right upper lobe of the lungs. The weights of the right and left lungs were 978 g and 780 g, respectively, and congestion was observed in the parenchyma. Froth was observed in the trachea and bronchi. No significant findings were observed in any of the remaining organs.
Considering the circumstances before death, intoxication by toxic substances was suspected, and blood, gastric contents, swabs from the burn lesions, lung tissue, and gas from the unruptured pulmonary bullae were collected for toxicological analysis of hazardous chemicals and gases. Gas sampling was performed using a 50 mL syringe filled approximately half-full of water to extract air from the pulmonary bullae before the lungs were removed. After air sampling, the syringe needle area was sealed with parafilm, and a portion of the right lung apex containing the pulmonary bullae was removed and immediately sent to the Forensic Toxicology and Chemistry Division for toxicological analysis.
In the toxicological examination, qualitative analysis detected toluene in the gastric contents, blood, lung tissue, and air collected from the pulmonary bullae. Quantitative analysis revealed toluene concentrations of 18.87 mg/L in the peripheral blood and 40.41 mg/ L in the cardiac blood. Toluene was not detected in the swab samples from the chemically burned skin lesions, which was attributed to the evaporation of toluene from the surface after prolonged exposure to air.
Based on the results of a comprehensive postmortem examination, including autopsy and laboratory tests, acute toluene intoxication was determined to be the cause of death.
Discussion
According to the Chemical Safety Agency, the extensive use of toluene in enclosed or poorly ventilated areas can increase exposure and cause irritation, and it is advised to consider controlling exposure through mechanical ventilation before beginning work involving toluene [1]. In addition, at least two workers, including an observer, are essential for safety and health monitoring. However, examining the situation of the deceased in this case, he was using a grinder alone inside the tank to remove synthetic latex residue without using a blower, and during the work, he used a cloth soaked in toluene. Here, we emphasize the dangers of working alone in hazardous environments.
The acute toxicity of toluene typically induces an anesthetic state in the central nervous system. According to the Korea Occupational Safety and Health Agency, inhalation of 100-200 ppm is associated with headaches, abdominal pain, and temporary irritation of the upper respiratory tract; 400 ppm with typical eye irritation, tearing, and hallucinations; and 600 ppm with fatigue, hallucinations, and slight nausea. Inhalation of 800 ppm is related to a metallic taste, immediate eye and upper respiratory tract irritation, a runny nose, drowsiness, motor disturbances, and dizziness. In cases of high-concentration exposure through inhalation, it can cause cerebellar dysfunction and decreased cognitive ability, with the acute oral lethal dose in humans estimated to be 50-500 mg/kg. Moreover, numerous reports have indicated that inhalation of toluene at concentrations above 40-100 ppm can lead to abnormalities in the human central nervous system [3]. According to previous literature, the toxic blood concentration of toluene has been reported to range from 0.3 to 83.5 mg/L, while the lethal concentration ranges from 2.1 to 110 mg/L [4].
Acute toxicity-related deaths after the use of volatile solvents, including sudden sniffing death syndrome, occur through various mechanisms, with catecholamine release being the most common cause of sudden death. In particular, it commonly occurs when hydrocarbons such as gasoline, benzene, trichloroethylene, or toluene are inhaled. Catecholamine release can cause supraventricular or ventricular tachyarrhythmia. Another mechanism of sudden death is acute hypoxia, which is described as follows: (1) direct toxicity from systemic absorption of volatile solvents after inhalation, causing central nervous system effects and reduced respiration; (2) suffocation from “bagging”—blockage of air into the lungs during inhalation; (3) asphyxiation caused by high concentrations of inhaled fumes displacing oxygen in the lungs; and (4) aspiration and choking from inhalation of vomitus after inhalant use, which can cause severe brain hypoxia and death [5]. Therefore, when handling highly volatile chemicals in a confined space, even short-term exposure can pose serious risks of poisoning and asphyxiation. Thus, adequate ventilation and other safety measures are considered essential in the work environment.
Direct contact with toluene can irritate the skin and mucous membranes, and chemical burns may occur, causing extensive tissue damage due to chemicals (acids, alkalis, and organic and inorganic compounds). Most organic solvents, including toluene, can extract fats or lipids from membranes, which constitute a protein-lipid matrix. Defatting causes irritation and cell damage, potentially leading to severe skin damage [6]. Well-defined erythema and blisters observed on the right arm, right thigh, and left iliac crest of the deceased were considered to be liquid burns consistent with chemical burns.
In the case of chemical exposure, securing samples is vital for toxicological confirmation. Unlike in vivo samples, postmortem samples face challenges owing to putrefactive changes. Key samples include femoral or cardiac blood, urine, vitreous humor, gastric contents, and organs. Alternative samples such as blood clots, cavity blood, cerebrospinal fluid, brain, spleen, bile, bone, synovial fluid, bone marrow, maggots, or skeletal muscle may be collected in specific cases. Quantitative analysis typically requires plasma, serum, or blood; however, these may be unavailable or of poor quality, and blood collection sites can affect xenobiotic concentrations [7]. For suspected volatile gas poisoning, the prompt collection of biological samples such as blood, urine, vitreous humor, gastric contents, or tissues is critical to minimize the loss or degradation of volatile substances, depending on the poison and the time since exposure [8].
In this case, unruptured pulmonary bullae were identified on PMCT, and the air within the bullae was sampled for gas analysis, in addition to blood and gastric contents. The toxic substance toluene was successfully analyzed in the air within the pulmonary bullae. However, quantitative analysis using air from the bullae could not be performed because such analysis generally requires at least 100 mL of sample. Nevertheless, in cases where blood-based toxicology testing is difficult—such as due to decomposition— if pulmonary bullae are present, gas analysis of these bullae may help detect toxic substances. In the future, it will be necessary to clearly identify the forensic applicability and limitations of gas analysis of pulmonary bullae through the accumulation of similar cases and systematic verification.
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