Instrumental analysis to prevent overlooking drugs in forensic autopsies of fire and drowning cases
2025 年 74 巻 1-2 号 p. 15-22
詳細
2025 年 74 巻 1-2 号 p. 15-22
This study focuses on fire and water cases that were subjected to forensic autopsies at Hiroshima University. It aimed to compare the results of rapid urinary drug screening kits with those obtained by instrumental analysis and evaluate the usefulness of instrumental analysis. This study included 102 fire and 64 water cases. False positives due to putrefactive amines were confirmed in stimulant tests in four fire cases and 18 water cases. In addition, although this did not result in a false-positive judgment for benzodiazepines, many benzodiazepines and their metabolites in the nine fire and four water cases were identified to be below the cutoff value. Moreover, prescription and over-the-counter drugs that did not show positive on rapid urinary drug screening kits were detected in fire and water cases, and drug concentrations in the blood reached toxic and lethal levels in three cases. The results of this study confirmed false positives and false negatives, and that there are many drugs that cannot be detected using rapid urinary drug screening kits. Although analytical instruments are expensive and require some specialized operators, its ability to detect a far greater variety of substances than rapid urinary drug screening kits makes it invaluable. In the future, drug testing using equipment should become more widespread in forensic science laboratories.
The examination of decedents discovered in fire or water cases presents unique challenges in forensic autopsies. One critical aspect that is often overlooked is the implementation of post-autopsy toxicological testing. The absence of such testing can substantially impede accurate determination of the cause of death. In cases where a drug overdose leads to unconsciousness followed by death due to fire or drowning, the true cause of death remains undetected without drug analysis. Moreover, failure to conduct drug tests may result in the oversight of criminal activities involving drugs, such as drug-facilitated homicide or suicide. With the continuous increase in population aging and life pressures, the annual incidence of drug overdoses and use has shown an upward trend. This issue is particularly globally prominent19). In Japan, the excessive use of hypnotic sedatives and antipsychotic medications is one of the main causes of death and hospitalization5,12). This omission not only hampers criminal investigations but also leaves potential crimes unresolved.
In many facilities, drug involvement during forensic autopsies is determined using rapid urinary drug screening kits8). However, these kits pose substantial risks of false positives and false negatives, which can lead to incorrect conclusions regarding the involvement of drugs in the cause of death. Furthermore, the number of pharmaceuticals that cannot be detected using these rapid urinary drug screening kits has recently increased. Consequently, instrumental analysis techniques, such as liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) are highly recommended14,15).
Instrumental analysis provides a high degree of accuracy and reliability in detecting and quantifying a wide array of substances, thus mitigating the risks associated with rapid screening methods. By incorporating LC-MS and GC-MS, forensic toxicologists can achieve a more comprehensive and precise identification of toxic substances2,3). This precision is crucial not only for determining the true cause of death, but also for ensuring the integrity of forensic investigations and subsequent legal proceedings. Therefore, the adoption of advanced instrumental analysis techniques is imperative for enhancing the accuracy of forensic toxicology and supporting the judicial process.
Despite the advantages of instrumental analysis mentioned above, correlations between the cause of death and carbon monoxide (CO) hemoglobin (carboxyhemoglobin: COHb) saturation or alcohol consumption are often examined in fire-related deaths4,17,21). However, few studies have explored the relationship between blood drug concentrations and the cause of death. Moreover, while several studies have identified a correlation between alcohol consumption and drowning6,13), the effects of drug intake on drowning remain unexplored. Investigating the role of drugs in fatalities recovered from fire scenes or water is crucial for determining the cause of death, yet this aspect has not been studied in detail. In this study, we performed both rapid urinary drug screening and instrumental drug analysis on bodies found at fire scenes and in water to examine potential correlations. Next, we compared the results of rapid urinary drug screening test and instrumental analysis to determine whether a correlation existed between the cause of death and drug intake, as well as to evaluate the risk of overlooking drug-related deaths. Furthermore, since numerous studies have already examined the relationship between cause of death and blood ethanol concentrations in bodies recovered from fire scenes or water4,6,7,13,18,20), ethanol was excluded from the scope of this study.
All standards were purchased from chemical reagent suppliers and gifted from various pharmaceutical companies. Only amphetamine was synthesized in our laboratory, because it cannot be purchased from chemical reagent suppliers or obtained from pharmaceutical manufacturers in Japan. Diazepam-d5 was purchased from Sigma-Aldrich (St Louis, MO, USA); LC–MS grade acetonitrile and methanol from FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan). All other chemicals were of analytical reagent grade and commercially available. Captiva EMR-Lipid and Captiva ND Lipids were purchased from Agilent Technologies (Santa Clara, CA, USA). Drug-free human whole blood and urine were purchased from BioIVT (Westbury, NY, USA).
Sample collectionBlood or urine samples were successfully collected from 102 fire and 64 water cases from January 2011 to December 2020 during forensic autopsies at Hiroshima University. This study was approved by the Ethics Committee of Hiroshima University (approval number: E2024-0194).
Urinary drug screening testTriage was performed according to the instructions provided in the user manual1). Urine (140 μL) was placed into the reaction cup using the provided pipette. The reaction mixture was held at room temperature for 10 min and then transferred to the drug detection zone. After the reaction mixture was fully absorbed, the zone was washed with three drops of the washing solution. Finally, the presence or absence of bands in the drug detection zone was determined as positive or negative, respectively.
COHb saturationThe two-wavelength procedure investigated was published by Sakai and Kojima16) and involved the transfer of 2.5 mL of 0.1% Na2CO3 to a quartz cuvette (1 cm path length) followed by 2 mg of sodium dithionite. Ten microliters of sample and 200 μL of 5 N NaOH were then added to the cuvette. The cuvette was capped and repeatedly inverted for mixing. The solution was allowed to stand for 5 min before analysis using UV–Vis spectrophotometry. The spectrophotometer was normalized to zero using distilled water prior to measuring the samples at 528 and 558 nm, using a ratio of 558:528 as the instrument signal, correlating to COHb saturation (%).
Sample preparation for instrumental analysisSamples for systematic drug screening were prepared according to the steps described below: an internal standard (diazepam-d5, 10 μg/mL, 5 μL) and 0.5 mL of acetonitrile were added to 0.1 mL of the blood or urine samples, and mixed thoroughly. The mixture was then centrifuged. The supernatant obtained was passed through a Captiva EMR-lipid cartridge (1 mL, 40 mg) (Agilent Technologies, Santa Clara, CA, USA). The eluate was concentrated to dryness under nitrogen stream. Methanol aqueous solution (30%; 0.1 mL) was added to the residue for re-dissolution and the resulting solution was used for LC-MS analysis.
Set-up for LC-MS/MSBlood and urine samples were analyzed using LC-MS/MS (Agilent Technologies 1,200 liquid chromatograph–6,420 quadrupole mass spectrometer). Separation was achieved by ZORBAX Eclipse Plus C18 (100 mm × 2.1 mm i.d., particle size of 3 μm) (Agilent Technologies). Mobile phases comprised 0.1% formic acid in water for solution “A” and 0.1% in acetonitrile for solution “B.” The column had isocratic elution in 5% B at 0.2 mL/min for 5 min, which was then developed using a linear gradient to 90% B over 40 min. This system can identify and quantify 400 drugs and their metabolites.
Comparison between the rapid urinary drug screening kit and the instrument analysisThe rapid drug test and instrument analysis were conducted using the same cutoff values for both methods. The cutoff value for the rapid urinary drug screening kit was based on the value proposed by the manufacturer.
The total number of cases discovered at the fire scene was 102, with 62 males (60.8%), 40 females (39.2%). The age groups with the highest proportions of decedents was 60–69 years (19.6%), followed by 70–79 years (18.6%). The mean age of decedents was 59.4 years. The proportion of male aged 0–79 years increased with age and peaked at 70–79 years; females had no significant differences between ages, with the highest proportion at 40–49 and 60–69 years.
Location of discoveryThe locations with the highest incidences of fires were house (78 cases, 76.5%), car (eight cases, 7.8%), and hotel (seven cases, 6.9%). In fire scenes, there was no statistically significant difference between male and female victims (Table 1).
Distribution of age and sex in fire and water cases
| Scene | Location | Average age | Sex |
|---|---|---|---|
| Fire scene | House | 61.7 | Female = 29 |
| (0.8–100) | Male = 49 | ||
| Car | 62 | Female = 3 | |
| (44–88) | Male = 5 | ||
| Hotel | 39.6 | Female = 4 | |
| (26–69) | Male = 3 | ||
| Bar | 27.3 | Female = 1 | |
| (18–36) | Male = 2 | ||
| Open area | 72 | Female = 1 | |
| (65–82) | Male = 2 | ||
| Others | 50.3 | Female = 2 | |
| (26–82) | Male = 1 | ||
| Water scene | Sea and beach | 56.2 | Female = 13 |
| (18–85) | Male = 20 | ||
| River | 57.9 | Female = 9 | |
| (23–88) | Male = 7 | ||
| Waterway | 48.8 | Female = 5 | |
| (0.7–83) | Male = 4 | ||
| Bath | 12.8 | Female = 1 | |
| (1.6–24) | Male = 1 | ||
| Others | 62.8 | Female = 3 | |
| (60–70) | Male = 1 |
Classification of the causes of death based on COHb saturation revealed that deaths due to CO poisoning (41.2%) accounted for the highest proportion (Table 2).
Cause of death in bodies found at fire and water scene
| Scene | Cause of death | N |
|---|---|---|
| Fire scene | Death from burning | 24 |
| Death from fire | 24 | |
| Carbon monoxide poisoning | 42 | |
| Others and unknown | 12 | |
| Water scene | Drowning | 42 |
| Shock | 6 | |
| Asphyxia | 2 | |
| Others and unknown | 14 |
The results are summarized in Table 3. For amphetamines, one case was positive with both the rapid urinary drug screening kit and instrumental analysis (true positives), four cases were positive with the rapid urinary drug screening kit but negative with instrumental analysis (false positives), and the remaining 97 cases were negative with both methods (true negatives). The rapid urinary drug screening kit exhibited a specificity of 0.96, an accuracy of 0.96, and a sensitivity of 1.
Summary of drug screening results
| Drug groups | TRUE Positive cases |
FALSE Negative cases |
FALSE Positive cases |
TRUE Negative cases |
Positive Predictive value |
Negative predictive value |
specificity | accuracy | sensitivity | |
|---|---|---|---|---|---|---|---|---|---|---|
| TP | FN | FP | TN | TP/(TP + FP) | TN/(TN + FN) | TN/(TN + FP) | (TN + TP)/N | TP/(TP + FN) | ||
| Benzodiazepines | Fire | 9 | 9 | 0 | 84 | 1 | 0.9 | 1 | 0.91 | 0.5 |
| Water | 6 | 4 | 0 | 54 | 1 | 0.93 | 1 | 0.94 | 0.6 | |
| Total | 15 | 13 | 0 | 138 | 1 | 0.91 | 1 | 0.92 | 0.54 | |
| Amphetamines | Fire | 1 | 0 | 4 | 97 | 0.2 | 1 | 0.96 | 0.96 | 1 |
| Water | 0 | 0 | 18 | 46 | 0 | 1 | 0.72 | 0.72 | — | |
| Total | 1 | 0 | 22 | 143 | 0.04 | 1 | 0.87 | 0.87 | 1 | |
| Barbiturates | Fire | 1 | 0 | 2 | 99 | 0.33 | 1 | 0.98 | 0.98 | 1 |
| Water | 1 | 0 | 1 | 62 | 0.5 | 1 | 0.98 | 0.98 | 1 | |
| Total | 2 | 0 | 3 | 161 | 0.4 | 1 | 0.98 | 0.98 | 1 | |
| Cocaine | Fire | 0 | 0 | 0 | 102 | — | 1 | 1 | 1 | — |
| Water | 0 | 0 | 0 | 64 | — | 1 | 1 | 1 | — | |
| total | 0 | 0 | 0 | 166 | — | 1 | 1 | 1 | — | |
| Tetrahydrocannabinol | Fire | 0 | 0 | 1 | 101 | 0 | 1 | 0.99 | 0.99 | — |
| Water | 0 | 0 | 4 | 60 | 0 | 1 | 0.94 | 0.94 | — | |
| total | 0 | 0 | 5 | 161 | 0 | 1 | 0.97 | 0.97 | — | |
| Opiates | Fire | 3 | 0 | 0 | 99 | 1 | 1 | 1 | 1 | 1 |
| Water | 0 | 0 | 0 | 64 | — | 1 | 1 | 1 | — | |
| total | 3 | 0 | 0 | 163 | 1 | 1 | 1 | 1 | 1 | |
| Phencyclidine | Fire | 0 | 0 | 0 | 102 | — | 1 | 1 | 1 | — |
| Water | 0 | 0 | 1 | 63 | 0 | 1 | 0.98 | 0.98 | — | |
| total | 0 | 0 | 1 | 165 | 0 | 1 | 0.99 | 0.99 | — | |
| Tricyclic antidepressants | Fire | 3 | 1 | 0 | 98 | 1 | 0.99 | 1 | 0.99 | 0.75 |
| Water | 1 | 0 | 2 | 61 | 0.33 | 1 | 0.97 | 0.97 | 1 | |
| total | 4 | 1 | 2 | 159 | 0.67 | 0.99 | 0.99 | 0.98 | 0.8 |
Numbers represent the case counts for each category.
N = 166 ( including 102 fire scece cases and 64 water scene cases ).
“—” indicates invalid data.
Positive predictive value, negative predictive value, specificity, accuracy, and snesitivity values are expressed as decimals.
True Positive: both urinary screening test and instrumental analysis are positive, True Ngative: both urinary screening test and instrumental
analysis are negative, False Positive: urinary screening test is positive and instrumental analysis is negative, False Negative: urinary screening kit
is negative, instrumental analysis is positive.
For benzodiazepines, nine cases were positive with both the rapid urinary drug screening kit and instrumental analysis (true positives), nine cases were negative with the rapid urinary drug screening kit but positive by instrumental analysis (false negatives), and the remaining 84 cases were negative with both methods (true negatives). The specificity, accuracy, and sensitivity of the rapid urinary drug screening kit were 1, 0.91, and 0.5, respectively.
For barbiturates, one case was positive with both the rapid urinary drug screening kit and instrumental analysis (true positives), and no case was negative with the rapid urinary drug screening kit but positive with instrumental analysis (false negatives). Two cases were positive with the rapid urinary drug screening kit but negative with instrumental analysis (false positives), and the remaining 99 cases were negative with both methods (true negatives). Specificity, accuracy, and sensitivity were 0.98, 0.98, and 1, respectively.
For tetrahydrocannabinoids, one case was positive with the rapid urinary drug screening kit but negative with instrumental analysis (false positives), and the remaining 101 cases were negative with both methods (true negatives). The specificity was 0.99 and accuracy was 0.99.
For opioids, three cases were positive with both the rapid urinary drug screening kit and instrumental analysis (true positives), and the remaining 99 cases were negative with both methods (true negatives). The sensitivity, accuracy, and specificity of the rapid urine screening kit were all 1.
For tricyclic antidepressants, three cases were positive with both the rapid urinary drug screening kit and instrumental analysis (true positives), one case was negative with the rapid urinary drug screening kit but positive with instrumental analysis (false negatives), and the remaining 98 cases were negative with both methods (true negatives). The specificity, accuracy, and sensitivity were 1, 0.99, and 0.75, respectively.
Although the results of the rapid urinary drug screening kit were negative, 14 medicines (including metabolites) and over-the-counter (OTC) drugs were detected in five cases using instrumental analysis, as shown in Table 4. The blood concentrations of citalopram and donepezil reached toxic levels, whereas the concentrations of etizolam, allylisopropylacetylurea, trazodone, amitriptyline, quetiapine, aripiprazole, 7-aminonitrazepam, and 7-aminoflunitrazepam reached therapeutic levels.
Fire incident with high concentration of drugs detected despite negative kit results by rapid urinary screening kit
| Case No. | Age | Sex | Blood concentration (ng/mL) | Urine concentration (ng/mL) | ||
|---|---|---|---|---|---|---|
| 1 | 40’s | F | Citalopram | 1,000 | Citalopram | 640 |
| 7-Aminonitrazepam | 63 | 7-Aminonitrazepam | 260 | |||
| 7-Aminoclonazepam | 66 | 7-Aminoclonazepam | 170 | |||
| 2 | 50’s | F | Etizolam | 101 | Etizolam | 84 |
| Etizolam M-III | 48 | Etizolam M-III | 394 | |||
| Etizolam M-VI | 23 | Etizolam M-VI | 776 | |||
| Zolpidem | 19 | Zolpidem | 9 | |||
| 3 | 70’s | M | Allylisopropylacetylurea | 7,000 | Allylisopropylacetylurea | 17,700 |
| Trazodone | 1,300 | Trazodone | 1,500 | |||
| Donepezil | 150 | Donepezil | 170 | |||
| 4 | 70’s | M | Amitriptyline | 454 | Amitriptyline | 2 |
| Quetiapine | 208 | Quetiapine | < LOQ* | |||
| 5 | 60’s | F | Aripiprazole | 172 | Aripiprazole | 39 |
| 7-Aminonitrazepam | 257 | 7-Aminonitrazepam | 350 | |||
| 7-Aminoflunitrazepam | 39 | 7-Aminoflunitrazepam | 93 | |||
Bold text indicates concentrations at toxic levels.
Underlined text indicates concentrations estimated to have medicinal effects.
*Values below the Limit of Quantification (LOQ = 1 ng/ml).
64 decedents were discovered in the water. The average age of the decedents was 53.9 years, with 14 decedents of unknown age. This study included 33 males and 31 females. No males were found in the age groups under 20 or over 80 years. The age group with the highest male mortality rate was 40–49 years, whereas the age group with the highest female mortality rate was 60–69 years.
Location of discoveryThe locations with the highest incidence of water were the sea and beach (33 cases, 51.6%), followed by rivers (16 cases, 25%), and waterway (nine cases, 14.1%). The locations with the fewest deaths were bathtubs and swimming pools. The male ratio was higher in the ocean on beaches, whereas the female ratio was higher in rivers. However, from a statistical perspective, there was no significant difference between the locations where males and females were found (Table 1).
Cause of deathIn water cases, the leading cause of death was drowning (65.6%), followed by shock (9.4%). The cause of death could not be determined for 12 patients (Table 2).
Comparison between the rapid urinary drug screening kit and the instrument analysisThe results are summarized in Table 3. For amphetamines, 18 of the 64 cases were positive with the rapid urinary drug screening kit but negative with instrumental analysis (false positives), while the remaining 46 cases were negative with both methods (true negatives). The rapid urinary drug screening kit exhibited a specificity of 0.72 and an accuracy of 0.72. Instrumental analysis revealed that putrefactive amines, which tested positive for stimulants using a rapid urinary drug screening kit, were detected in all 18 cases.
For benzodiazepines, six cases were positive with both the rapid urinary drug screening kit and instrumental analysis (true positives), four cases were negative with the rapid urinary drug screening kit but positive with instrumental analysis (false negatives), and the remaining 54 cases were negative with both methods (true negatives). The specificity, accuracy, and sensitivity of the rapid urine drug screening kit were 1, 0.94, and 0.6, respectively.
For barbiturates, one case was positive with both the rapid urinary drug screening kit and instrumental analysis (true positive), no case was negative with the rapid urinary drug screening kit but positive with instrumental analysis (false negative), one case was positive with the rapid urinary drug screening kit but negative with instrumental analysis (false positive), and the remaining 62 cases were negative with both methods (true negative). Specificity, accuracy, and sensitivity were 0.98, 0.98, and 1, respectively.
For tetrahydrocannabinoids, four cases were positive with the rapid urinary drug screening kit but negative with instrumental analysis (false positives), and the remaining 60 cases were negative with both methods (true negatives). The specificity was 0.94 and accuracy was 0.94.
For tricyclic antidepressants, one case was positive with both the rapid urinary drug screening kit and instrumental analysis (true positives); no case was negative with the rapid urinary drug screening kit but positive with instrumental analysis (false negatives); two cases were positive with the rapid urinary drug screening kit but negative with instrumental analysis (false positives); and the remaining 61 cases were negative with both methods (true negatives). Specificity, accuracy, and sensitivity were 0.97, 0.97, and 1, respectively.
Although the results of the rapid urinary drug screening kit were negative, nine medicines (including metabolites) and OTC drugs were detected in four patients using instrumental analysis, as shown in Table 5. The blood concentration of trazodone reached toxic levels, whereas the concentrations of etizolam, lormetazepam, zolpidem, and suvorexant reached therapeutic levels.
Water incident with high concentration of drugs detected despite negative kit results by rapid urinary screening kit
| Case No. | Age | Sex | Blood concentration (ng/mL) | Urine concentration (ng/mL) | ||
|---|---|---|---|---|---|---|
| 6 | 60’s | F | Etizolam | 12 | Etizolam | 13 |
| Etizolam M-III | 43 | Etizolam M-III | 420 | |||
| Etizolam M-VI | 11 | Etizolam M-VI | 40 | |||
| 7 | 50’s | M | Tramadol | 4,300 | Tramadol | 51,100 |
| Acetaminophen | 190 | Acetaminophen | 250 | |||
| Lormetazepam | 150 | Lormetazepam | 50 | |||
| 8 | 40’s | F | Zolpidem | 45 | Zolpidem | 28 |
| Paroxetine | 44 | Paroxetine | 112 | |||
| 9 | Unknown | F | Suvorexant | 378 | — | — |
Bold text indicates concentrations at toxic levels.
Underlined text indicates concentrations estimated to have medicinal effects.
Case NO. 9 was not subjected to urine concentration testing.
In cases of death from burning, death from fire, or CO poisoning, the detection of drugs in the decedent complicates the cause of death. COHb saturation can aid to estimate the cause of death, but if drugs are detected from the blood or urine, the decedent’s ability to escape a fire must be evaluated by the concentration of drugs in blood. The drugs may have been self-administered or administered by others; therefore, the check of prescription history is also necessary from the decedent or related persons. Forensic scientists must adopt a multifaceted approach, carefully analyzing the pharmacological effects of the detected drugs and their interactions with the primary cause of death to accurately determine the cause of death in these complex cases.
In cases where bodies are found in the water, the presence of diatoms in the lungs and the detection of drugs significantly affect the determination of the cause of death. Diatoms can indicate drowning if found in the lungs, whereas the presence of drugs requires careful assessment to determine whether they contribute to incapacitation or other factors that lead to death. Forensic scientists must analyze both biological and toxicological evidence to accurately ascertain the cause of death in these situations.
Rapid urinary drug screening kit showed false positives for amphetamines in 4 of 102 cases at fire scenes and 18 of 64 cases of water. Instrumental analysis revealed that putrefactive amines, such as phenethylamine, tyramine, and tryptamine, were detected in all cases, and it was estimated that these amines caused the positive results for amphetamines. In particular, decedents discovered from water are often in an advanced state of decomposition because of the long time that has passed since they were discovered. Putrefactive amines show positive results for amphetamines in rapid urinary drug screening kits9). Although there is a need to improve the cross-reactivity of these putrefactive amines with amphetamines, it is currently difficult to improve the selectivity of rapid urinary drug screening kits and this is the limit of rapid urinary drug screening kits.
Additionally, false-negative results for benzodiazepines were identified in nine of 102 fire scenes and four of 64 water cases. Small amounts of benzodiazepines and/or its metabolites were detected in urine in all cases using instrumental analysis. Therefore, it is speculated that the cause of false negatives was the substrate selectivity of the rapid urinary drug screening kit or the difference in detection ability between the rapid urinary drug screening kit and instrumental analysis11). Flunitrazepam is prescribed in large quantities and is one of the drugs that causes crimes and accidents. Flunitrazepam has a low effective blood concentration, and is chemically transformed into 7-aminoflunitrazepam after death or before analysis. Furthermore, 7-aminonitrazepam is difficult to detect because it has low reactivity with rapid urinary drug screening kits. Etizolam (Depas®) is one of the most commonly prescribed drugs in Japan. This drug has attracted attention as a serious problem because it tested negative in rapid urinary drug screening kits, even in cases of overdose. Etizolam was detected in this study; however, the rapid urinary drug screening kit yielded negative results. In this study, we used Triage as a rapid urinary drug screening kit, but since there are also commercially available rapid urinary drug screening kits with different substrate specificities, it is recommended to use different kits depending on the purpose10).
There is also a problem with the detection of tricyclic antidepressants as they cross-react with atypical psychotropic drugs, such as chlorpromazine and quetiapine. This reduces the specificity of the rapid urinary drug screening kit, and is a drawback in quality. However, from the perspective of screening a wide range of drugs, this can be considered advantageous.
Several drug groups that can be detected using rapid urinary drug screening kits are subject to legal restrictions. However, many prescription drugs and drugs of abuse have not shown positive results with the rapid urinary drug screening kits, making it difficult to determine whether someone has used the drugs using a rapid urinary drug screening kit. Therefore, the widespread use of simple and rapid instrumental analyses is desirable to avoid overlooking drug use. In this study, rapid urinary drug screening tests were negative in five of the 102 fire cases; however, many types of drugs and metabolites (allylisopropylacetylurea, 7-aminoflunitrazepam, 7-aminonitrazepam, amitriptyline, citalopram, donepezil, etizolam, quetiapine, and trazodone), which could not be detected by rapid urinary drug screening kits, were detected using instrumental analysis, as shown in Table 4. At the time of the fire, the blood concentrations of these sleeping pills (allylisopropylacetylurea, 7-aminoflunitrazepam, 7-aminonitrazepam, and etizolam) were at levels where medicinal effects were expected in three cases (cases 2, 3, and 5 in Table 4). Although it is unlikely that these patients had acute drug poisoning, the risk of late escape cannot be ruled out. However, acute drug poisoning involving citalopram and donepezil was suspected in two cases (cases 1 and 3 in Table 4). Furthermore, in four of the 64 water cases, simple drug tests yielded negative results; however, some drugs (acetaminophen, etizolam, lormetazepam, paroxetine, suvorexant, and zolpidem) that could not be detected by the rapid urinary drug screening kit were detected using instrumental analysis, as shown in Table 5. The blood concentrations of these sleeping pills (etizolam, lormetazepam, suvorexant, and zolpidem) at the time of death were at levels where medicinal effects were expected in all four cases (Table 5), but the risk of unsteadiness or other effects on gait could not be ruled out. In one case, acute drug poisoning (tramadol) was suspected (case 7 in Table 5). This accounted for five out of 102 fire cases and four out of 64 water cases, raising the possibility of potential underreporting of drug-related fatalities by rapid urinary drug screening kits. Therefore, these findings suggested that without confirmatory instrumental analysis, drug involvement in these deaths could have been overlooked. Consequently, our study highlights the critical need for comprehensive testing to accurately determine the cause of death.
In forensic autopsies, drug testing does not allow the estimation of drugs based on toxidrome; therefore, drug tests that assume the involvement of all drugs are required. Although it takes longer to obtain test results than with rapid urinary drug screening kits, this allows for testing with a lower chance of missing anything. For these reasons, it can be concluded that the use of instrumental analysis is useful for drug testing after forensic autopsy.
Rapid drug tests offer the advantage of being simple and providing quick results; however, false positives and false negatives are inevitable. In this study alone, nine cases were identified as potential drug-related deaths. Additionally, 17 types of drugs and metabolites were detected only through instrumental analysis. These findings highlight the high risk of missing drug-related deaths when relying solely on simple tests and emphasize the necessity of instrumental analysis. Although drug-testing equipment is expensive and requires specialized operators, its ability to detect a far greater variety of substances than rapid urinary drug screening kits makes it invaluable. In the future, drug testing using equipment should become more widespread in forensic science laboratories.
The authors would like to thank Dr. Touko Morinobu of School of Medicine, Hiroshima University for her support to this study and the staff of Department of Forensic Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University.
The authors declare no conflict of interest in relation to this work.
No funding was received to assist with this study.
