Relato de Caso
SODIUM NITRITE SELF-POISONING: A CASE STUDY IN MATO GROSSO
Como citar: Zaghetto WDC, Both IW. Autoeliminação por nitrito de sódio: estudo de caso em Mato Grosso. Persp Med Legal Pericia Med. Vol. 11, 2026; 260101.
https://dx.doi.org/10.47005/260101
Recebido em 27/12/2025
Aceito em 12/01/2026
The authors report no conflict of interest.
SODIUM NITRITE SELF-POISONING: A CASE STUDY IN MATO GROSSO
Resumo
INTRODUÇÃO: O uso de nitrito de sódio como método de autoeliminação tem crescido no Brasil, impulsionado pelo acesso facilitado a fóruns online e mercados digitais que instruem o consumo da substância. APRESENTAÇÃO DO CASO: Relata-se caso ocorrido em Cuiabá, Mato Grosso, envolvendo vítima masculina com vestígios de aquisição online e ingestão planejada. Os exames cadavéricos revelaram livores hipostáticos intensos e cianose, enquanto a análise toxicológica identificou 28,08 mg/ml de nitrito de sódio no conteúdo gástrico e a presença de alprazolam, geralmente utilizado para reduzir efeitos colaterais da intoxicação. DISCUSSÃO: Os achados corroboram a literatura sobre metemoglobinemia e destacam a importância da integração entre a perícia de local, a necrópsia e exames laboratoriais para a elucidação do óbito, superando as dificuldades técnicas de detecção do composto diluído. CONCLUSÃO: O caso evidencia a urgência em regulamentar a venda online de compostos letais e a necessidade de aprimorar métodos de detecção forense, além de reforçar ações de prevenção ao suicídio e controle de informações que incentivam o método.
Palavras Chave: Nitrito de Sódio, Suicídio, Toxicologia Forense, Metemoglobinemia, Cenas de Crimes
Abstract
INTRODUCTION: The use of sodium nitrite as a suicide method is increasing in Brazil, facilitated by easy access to online forums and digital marketplaces. CASE PRESENTATION: This paper reports a case in Cuiabá, Mato Grosso, highlighting evidence consistent with the modus operandi described in literature, such as online acquisition, manipulation, and dilution for ingestion. Autopsy revealed intense hypostatic livor and cyanosis, while toxicological analysis identified 28.08 mg/ml of sodium nitrite in gastric content and the presence of alprazolam, used to mitigate intoxication side effects. DISCUSSION: The study underscores the vital importance of integrating crime scene investigation, post-mortem examination, and specialized laboratory analysis to overcome technical detection hurdles and confirm the diagnosis. CONCLUSION: This case highlights the urgent need to improve forensic detection methods and regulate the online sale of lethal compounds, while reinforcing the relevance of suicide prevention and information control strategies.
Keywords (MeSH): Sodium Nitrite, Suicide, Forensic Toxicology, Methemoglobinemia, Crime Scenes.
1.INTRODUCTION
Intentional self-poisoning, although statistically less frequent than traditional methods (such as hanging, firearms, or jumping from heights), has been gaining prevalence. Easy access to information has facilitated the dissemination of alternative methods of self-harm, especially via the deep web, forums, and websites containing high-risk content for vulnerable individuals. This trend primarily affects the youth population, who maintain higher engagement with information and communication technologies (1).Studies indicate an increase in recorded cases of self-elimination using sodium nitrite. In the United States, for instance, there was a 253% increase in nitrite/nitrate self-poisoning cases, with a 166% rise in fatalities between 2018 and 2021, according to official NVDRS (National Violent Death Reporting System) data. In absolute numbers, 260 suicides via nitrite/nitrate poisoning were recorded nationwide between 2018 and 2020 (2).
1.1 SODIUM NITRITE AND THE HUMAN BODY
Sodium nitrite is classified as an inorganic salt (NaNO₂), it is a white, odorless solid, and water-soluble. Readily available for purchase on online platforms, it has a wide range of applications in the textile, construction, and petroleum industries, and in medicine (as an antidote for cyanide poisoning). Its most well-known use is in food preservation, particularly for red meats, fish, and seafood, where it preserves color and extends shelf life (3).Regulated by ANVISA (National Health Surveillance Agency) and listed as a food additive with usage limits defined by collegiate resolutions, sodium nitrite remains easily acquired, especially in digital environments (4).According to most literature, the human body can tolerate a relatively high dose of the compound—with reports of survival at 6 grams—but doses exceeding 1 gram can be lethal. Nitrite is considered ten times more toxic than nitrate, with a lethal dose ($LD$) for humans ranging from 33 to 250 mg/kg. In rats, the oral LD50 is 175 mg/kg (5).
For suicidal purposes, sodium nitrite has been acquired primarily through digital means, either isolated or in “suicide kits,” under the false promise of a “painless” death. These kits typically include the salt, a container, and adjuvant medications such as gastric protectors (ranitidine, omeprazole), antiemetics (ondansetron, metoclopramide), and sedatives (alprazolam, clonazepam, zolpidem) intended to minimize side effects and induce sleep (6).
Sodium nitrite poisoning causes methemoglobinemia, a condition that impairs oxygen transport to tissues. This salt oxidizes the heme iron of hemoglobin from the ferrous state (Fe²⁺) the ferric state (Fe³⁺). This alteration of the redox state of the heme group, caused by the removal of an electron from the iron within hemoglobin, forms methemoglobin (3, 7, 8, 9).This impairs oxygen delivery and exchange, as methemoglobin is incapable of binding to oxygen, leading to anemic hypoxemia. Symptoms include nausea, vomiting, lethargy, shortness of breath, abdominal pain, tachypnea, dyspnea, facial flushing, cyanosis, seizures, coma, cardiac arrest, and ultimately, death (3, 7, 8, 9).
It is important to note that pure sodium nitrite in solid form can be easily analyzed in the laboratory via colorimetric methods. However, once dissolved in water, detection becomes more difficult, requiring sophisticated methods such as ion chromatography, which are not always available in routine forensic investigations. Quantifying the compound presents further technical challenges, requiring specific methodologies. Therefore, a multidisciplinary approach integrating crime scene investigation, death scene examination (perinecroscopy), and autopsy (necroscopy) in conjunction with laboratory tests is essential for diagnosing death by sodium nitrite poisoning (3).
1.2 OBSERVED CRIME SCENE PATTERNS
In scenes associated with this type of poisoning, it is common to find product bottles—often purchased online—precision scales, measuring spoons, various medications (hypnotics, antidepressants, antacids, and antiemetics), and items related to “departure rituals,” such as suicide notes and alcoholic beverages. Medical prescriptions for anxiety and depression are also frequent. Electronic devices often reveal access to websites and forums with detailed suicide protocols, including preparation instructions, dosages, and pharmacological combinations (2, 3, 6, 9, 10, 11).
During the external examination (perinecroscopy), pronounced hypostasis (lividity) with violaceous tones is noted, along with cyanosis of the lips and nails, and facial congestion. Recent emesis (vomiting) is observed in many cases (2, 3, 6, 9, 10, 11).
2. CASE PRESENTATION
2.1 SCENE INVESTIGATIONA
Male victim, aged 55–60, was found deceased on a bed in his apartment. A smartphone was nearby. On the nightstand, investigators found a plate, a metal spoon, and three cups—two containing transparent liquid and one with white powder residue. A plastic bucket on the floor contained another cup with a substance matching the granulometric and color characteristics of sodium nitrite, immersed in a small amount of transparent liquid (Figure 1).
Figure 1: Household containers containing liquids and powder residues.
In the kitchen, an empty alprazolam blister pack, a food scale, a cardboard box with a shipping label, and a 500g bottle of ACS-grade (A.R) sodium nitrite were found. The bottle was purchased online and delivered to the victim at an affordable price without sales control (Figure 2).Various medications and prescriptions for anxiety and depression were found in the apartment. The cadaver exhibited pronounced grayish hypostasis, a cyanotic face with fluid exudation from the nostrils, and purple discoloration of the fingertips, nails, and lips (Figure 3).
Figure 2: Empty alprazolam blister pack.
Figure 3: Shipping box, food scale, and sodium nitrite bottle.
2.2 AUTOPSY FINDINGS (NECROSCOPY)
External examination at the Medical Examiner’s Office revealed facial cyanosis, intense scleral congestion with bilateral ocular and periocular petechiae (Figure 4), gray coloration of the lips and tongue, gingival dehydration and cyanosis (Figure 5), and ungual cyanosis in all extremities. Hypostasis was irregular, showing red areas mixed with grayish and purple tones (Figure 6).
Figure 4: Scleral congestion with bilateral ocular and periocular petechiae.
Figure 5: Gray tongue, gray lips, and gingiva with dehydration and cyanosis.
Figure 6: Anterior livor mortis displaying grayish and reddish-purple tones.
Internal examination was performed using the Rokitansky technique. Findings included transparent frothy fluid in the trachea (Figure 7), identical to that found in the stomach. The lungs showed marked congestion, edema, and subpleural petechiae. Compression of the lung tissue resulted in the expression of frothy fluid. The blood and myocardium exhibited a distinct dark brown (chocolate-colored) hue (Figure 8). Abdominal examination revealed generalized visceral congestion.
Figure 7: Clear, frothy liquid in the trachea.
Figure 8: Heart with dark brown discoloration.Figura 8: coração com tonalidade marrom escuro.
2.3 COMPLEMENTARY EXAMS
Blood and gastric content samples were collected for toxicological analysis. Blood samples detected mass spectra compatible with dipyrone and alprazolam.The gastric content was analyzed via Potentiometric Titration (Metrohm 848 Titrino Plus) at the ICET-UFMT Laboratory using the MET (Monotonic Equivalence Point Titration) methodology. Sodium nitrite was detected at a concentration of 28.08 mg/mL.Histopathological analysis of the brain, lungs, heart, liver, and kidneys was performed. The brain showed post-mortem hypoxic-ischemic changes. The lungs showed edema, congestion, hyperinflation, and focal intra-alveolar and interstitial hemorrhage. The liver showed sinusoidal dilation and mild macro- and microvesicular steatosis. The kidneys were congested, and the heart was within normal histological limits.
3. DISCUSSION
Suicide rates in Brazil are trending upward, with 147,698 recorded cases between 2011 and 2022, primarily among men over 25 (1). Based on the scene characteristics, autopsy findings, and toxicological analysis, death by sodium nitrite intoxication is evident. Evidence of preparatory acts was found, including the online purchase, the use of scales for dosing, and dilution for ingestion.The presence of alprazolam suggests prior knowledge of the poisoning’s side effects, such as nausea and vomiting. Regarding autopsy findings, Barranco (12) described the lividity as blue-red livor. This study also found bilateral pulmonary edema, subpleural petechiae, intense visceral congestion, and subungual cyanosis.Durão described the livor as brown-gray-blue-red and noted general signs of asphyxia and “chocolate brown” blood (6). While some authors reported a brown gelatinous substance in the stomach, this was not observed in the present case (6, 12). Most studies report facial congestion and cyanosis of the oral mucosa, though Hwang reported a dark brown face and bright red oral mucosa (13).Our findings corroborate Dean regarding the brown myocardium and Durão and Mañibo regarding the brown blood (3, 6, 14). The lack of standardized terminology among authors highlights the need for protocol normalization.In the Brazilian context, mandatory notification of exogenous poisoning is required by Law 6.259/1975 and the Code of Medical Ethics via SINAN – Notifiable Diseases Information System, using ICD-10 T65.9 (Toxic effect of unspecified substance), as sodium nitrite does not have a specific code.
4. CONCLUSION
Sodium nitrite poisoning is an emerging public health issue. Increased international and national reporting (São Paulo, Distrito Federal, and Mato Grosso) necessitates urgent scientific dissemination. Forensic recognition is vital given the technical difficulties in toxicological detection and the current low frequency of the method.Health authorities must be alerted to the ease of online acquisition. Stricter regulations, requiring proof of professional need (food or chemical industry) at the time of purchase, are recommended to restrict access for the general public. This study reinforces the need for public mental health policies and investment in specialized forensic detection methodologies for routine laboratory use.
5. ACKNOWLEDGMENTS
The authors would like to thank our colleagues at POLITEC (Official Forensic and Identification Bureau of Mato Grosso), who spared no effort to ensure the completion of this study. Special thanks to Official Experts Oliver Guilherme da Silva (Medical Examiner) and Ana Sofia Alves (Forensic Expert), who were responsible for the histopathological and toxicological examinations, respectively.
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