Fatal methemoglobinemia in three suicidal sodium nitrite poisonings

Special Report from the CDC: Suicide rates, sodium nitrite-related suicides, and online content, United States

BACKGROUND

In 2022, suicide ranked as the 11th leading cause of death in the United States with 49,513 deaths. Provisional mortality data from 2022 indicate a 2.8% increase in the number of suicides compared to 2021. This paper examines overall suicide trends, sodium nitrite ingestion as an emerging suicide method, and the role that online forums play in sharing information about suicide methods (including sodium nitrite ingestion).

METHODS

Suicides were identified from CDC's National Vital Statistics System (2018-July 2023 provisional) multiple cause-of-death mortality files using International Classification of Diseases (ICD), Tenth Revision underlying cause-of-death codes U03, X60-X84, and Y87.0 and T code T50.6 (antidotes and chelating agents). Google search popularity metrics were captured from January 2019 to January 2023. Case reports of sodium nitrite related suicide and suicide attempts (through February 2024) were identified in the medical and forensic literature.

RESULTS

At least 768 suicides involving antidotes and chelating agents (including sodium nitrite) occurred between 2018 and July 2023, set in the context of 268,972 total suicides during that period. Overall, suicides involving antidotes and chelating agents (including sodium nitrite) represent <1% of all suicides, however, numbers are rising.

CONCLUSIONS

Suicide methods are known to change over time. These changes can be influenced by, among other factors, online forums and means accessibility, such as internet purchase availability. CDC remains committed to prevention through comprehensive public health strategies that protect individuals, families, and communities.

PRACTICAL APPLICATIONS

States and community partners might consider leveraging physicians, emergency responders, and other appropriate crisis response groups to disseminate information on sodium nitrite self-poisoning and its antidote, methylene blue. Efforts should be part of a comprehensive public health approach to suicide prevention.

Modern suicide trend from internet

INTRODUCTION

The most common suicide methods vary slightly from country to country, partly related to the availability of effective means. Societal development over the years and especially the advent of the Internet has enabled the sudden spread of new suicide methods. Recently, especially since 2019, intentional sodium nitrite poisoning has appeared on many social networks as an increasingly popular method of suicide.

MATERIAL AND METHODS

There was performed a retrospective-prospective study of the autopsy protocols of the Medico-Legal Departments of the Healthcare Surveillance Authority in Slovakia, in a period of 15 years (2008-2022). We performed the analysis of cases of death due to nitrite poisoning, focusing on cases of intentional self-harm. In all selected cases, we present complete information, including photo documentation from the place of death, as well as the results of the performed autopsy and the results of additional laboratory examinations.

RESULTS

We did not record any fatal cases of unintentional, accidental consumption of sodium nitrite in Slovakia, nor any fatal cases of homicidal poisoning by this substance. However, there were three cases of intentional self-harm (completed suicide) by sodium nitrite poisoning (in 2019, 2020 and 2022).

CONCLUSIONS

The correct diagnosis of the cases of sodium nitrite poisoning deaths is possible only based on evaluating all the information obtained, a thorough examination of the body and the crime scene, and the correct interpretation of the findings found during a subsequent autopsy and the results of the toxicological analysis.

Systematic Review of Fatal Sodium Nitrite Ingestion Cases: Toxicological and Forensic Implications

Documented cases of sodium nitrite toxicity are almost exclusively caused by accidental ingestion; however, self-poisoning with sodium nitrite represents an increasing trend in nitrate-related deaths. This systematic review summarizes the most crucial evidence regarding the fatal toxicity of sodium nitrite. It identifies gaps and differences in the diagnostic forensic approaches and the detection methods of sodium nitrite intoxication. A total of eleven research articles were selected for qualitative and quantitative data. Most of the studies (6/11) were case reports. Fifty-three cases of fatal intoxication with sodium nitrite were chosen for the review. More research is required to develop cost-effective techniques and uniform cutoffs for blood nitrite and nitrate levels in the event of deadly sodium nitrite poisoning. There is still a lack of critical information on other matrices and the impact of time since death on toxicological results in such situations. The available evidence provides useful recommendations for forensic pathologists and health practitioners engaged in instances of sodium nitrite poisoning or death. The data should also set off alarm bells in the public health system, in prosecutor's offices, and for policymakers so that they may undertake preventative measures to stop and restrict the unregulated market for these substances.

Impact of methemoglobin on carboxyhemoglobin saturation measurement in fatal sodium nitrate and sodium nitrite cases

An increase in suicide cases by sodium nitrate and sodium nitrite ingestion has been noted in the scientific literature. We report on the possible impact of nitrate/nitrite-caused methemoglobinemia on carboxyhemoglobin measurement by spectrophotometric methods. Elevated methemoglobin saturation may result in insufficient reducing agents to convert methemoglobin into deoxygenated hemoglobin, affecting the measured total hemoglobin and carboxyhemoglobin saturation. We highlight four cases where the cause of death was attributed to sodium nitrate or sodium nitrite ingestion. The possible impact of the nitrate/nitrite-caused methemoglobinemia on the carboxyhemoglobin saturation as measured by spectrophotometry is discussed. Further studies are needed to identify a causal relationship between nitrate/nitrite-caused methemoglobinemia and carboxyhemoglobin saturation as measured by spectrophotometric methods.

Nitrites: An Old Poison or a Current Hazard? Epidemiology of Intoxications Covering the Last 100 Years and Evaluation of Analytical Methods

In recent times, there has been a concerning and noteworthy rise in the global use of sodium nitrite for suicidal purposes. This is facilitated either through the employment of specialized "suicide kits" or by acquiring sodium nitrite through alternative means. Additionally, another occurrence contributing to nitrite poisoning is the recreational utilization of nitrites in the form of volatile aliphatic esters of nitrous acid, commonly referred to as "poppers". Based on current available papers and reports on the subject of nitrates, nitrites, and poppers intoxications, an epidemiological analysis and evaluation of analytical methods were performed. A total of 128 papers, documenting a collective count of 492 intoxication cases, were identified. Additionally, in order to complete the epidemiological profile of nitrite poisoning, the authors briefly examined six cases of nitrite intoxication that were under investigation in our laboratory. Furthermore, a review of nitrite poisoning cases over the past 100 years shows that the old poison is still in use and poses a substantial risk to society.

A fatal suicidal sodium nitrite ingestion determined six days after death

Sodium nitrite (SN) is an inorganic salt that appears as a slightly yellowish crystalline solid, odorless, and highly soluble in water at room temperature. It is highly toxic to humans at specific doses because it can oxidize hemoglobin to methemoglobin, causing severe tissue hypoxia. A 20-year-old woman was unconscious in her bedroom and died shortly after that. Two days later, following the discovery of a jar of SN and a paper in which were written instructions on how to take it (and the website from which the procedure was learned) in the same room were death occurred, the Judicial Authority ordered the execution of the autopsy on the exhumed body of the young woman. The autopsy procedure was performed ∼ 2h after exhumation. It showed greyish-purple hypostasis, labial cyanosis, stomach distension and greenish color but empty, subpleural petechiae, brownish fluid in the pleural cavities (∼300 ml), congested and edematous lungs and diffuse visceral congestion. At autopsy, foamy liquid was observed at the lung section and subsequent squeezing. In addition, the autopsy showed edema and hemorrhagic petechiae of the laryngeal, glottal, and tracheal submucosa and green-brownish foamy liquid in the tracheal lumen. The cause of death was attributed tocardiac arrest induced by anoxia resulting from acute methemoglobinemia caused by sodium nitrite poisoning, intensified by severe malnutrition. Manner of death was suicidal.

Sodium nitrite poisoning: A series of 20 fatalities in which post-mortem blood nitrite and nitrate concentrations are reported

Sodium nitrite has several industrial applications however its accidental or intentional ingestion has been associated with severe toxicity and death. We present a series of 20 cases over 2 years in which evidence of sodium nitrite ingestion was found at the scene and supported by biochemical analysis of post-mortem blood nitrite and nitrate levels. Routine toxicological screening was performed on post-mortem blood samples received at University Hospitals of Leicester (UHL) NHS Trust, including ethanol analysis by headspace gas chromatography-flame ionisation detection (HS GC-FID), drug screening by high resolution accurate mass-mass spectrometry (HRAM-MS) and confirmatory drug quantitation by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cases in which the history indicated the possibility of nitrite salts present at the scene, purchase of a suicide kit or a dusky-ash appearance of skin on post-mortem were referred to a specialist laboratory for nitrite and nitrate analysis. Analysis was based upon the gas-phase chemiluminescent reaction between nitric oxide (NO) and ozone; NO levels were determined using an NOA 280A, Sievers NO analyser. Twenty post-mortem cases in which sodium nitrite ingestion was the most probable cause of death were reported between January 2020 and February 2022; mean age was 31 years (range 14-49) with 9/20 (45%) female. 16/20 (80%) of cases had a history of depression and / or mental health issues. In half of the cases, anti-depressant / anti-psychotic drugs were prescribed; these drugs were detected in 8/20 (40%) cases. Ethanol was detected in 4/20 (20%) cases and anti-emetic drugs in 7/20 (35%) cases; anti-emetic drugs may be used to aid retention of sodium nitrite. Illicit drugs (amphetamine, cannabis and cocaine) were present in 3/20 cases (15%). Nitrite was found to be elevated in all but one case (95%), and nitrate was elevated in 17/20 (85%) cases. This paper highlights a surge in numbers of deaths across England and Wales due to sodium nitrite toxicity. Although, nitrite poisoning remains a rare cause of death, it is worthwhile considering its use in individuals with suicidal ideation given its unregulated availability online. The detection and quantitation of nitrite and nitrate requires specialised, highly reliable methodology currently only available in research laboratories. Implication of sodium nitrite ingestion also relies heavily upon circumstantial evidence combined with quantification. The provision of a quantitative nitrite / nitrate analytical service greatly assists in determining the cause of death in these cases.

A turn-on fluorescent nano-probe base on methanobactin-AuNPs for simple and efficient detection of nitrite

Nitrite ions are important markers threatening humans and environmental security. A highly selective method for rapid detection of nitrite needs to be developed. Herein, a novel and rapid fluorescence method for nitrite determination is established on the basis of diazotization-coupling reaction of methanobactin (Mb) extracted by Methylosinus trichosporium OB3b with nitrite on the fluorescence. In the presence of gold nanoparticles (AuNPs), the fluorescence of AuNPs was strongly quenched by the Mb because the sulfhydryl or amino structures on the surface of Mb could be bound to the surface of AuNPs by forming Au-S or Au-N bonds. Upon addition of nitrite, the Mb easily reacts with nitrite to form azo products in the acidic medium. Then, with the increase of nitrite concentration, the Mb-AuNPs fluorescence was gradually recovered, realizing the turn-on fluorescence sensing of nitrite. Under optimal conditions, the proposed method has a good linear relationship with nitrite concentration in the range of 0-8.0 μM and 8.0-50.0 μM, and the detection limit is 16.21 nM. In addition, satisfactory results were obtained for nitrite analysis using milk, ham sausage and leaf mustard as real samples, which demonstrated that the method as-developed would have great practical application prospects.

Sodium Nitrite Intoxication and Death: Summarizing Evidence to Facilitate Diagnosis

BACKGROUND

Over the years, forensic pathology has registered the spread of new methods of suicide, such as the ingestion of sodium nitrite. Sodium nitrite causes increased methemoglobin, resulting in systemic hypoxia, metabolic acidosis, and cyanosis. Since sodium nitrite is a preservative, the ingestion of foods containing an excessive amount of this substance can also cause acute intoxication up to death. The present review is aimed at guiding health professionals in the identification and management of sodium-nitrite-related intoxications and deaths.

METHODS

A systematic literature search was carried out on PubMed by following the PRISMA statement's criteria. A total of 35 studies with 132 cases were enrolled, and the data were cataloged in Microsoft Excel. To establish the causal correlation between sodium nitrite ingestion and death, the Naranjo Adverse Drug Reaction Probability Scale was used.

RESULTS

In addition to the small number of cases that have currently been published, the study demonstrated that there was a general methodological discrepancy in the diagnostic process. However, some interesting results have emerged, especially in post-mortem diagnostics.

CONCLUSION

Sodium-nitrite-related deaths represent a challenge for forensic pathologists; therefore, it is important to promptly recognize the essential features and perform the necessary and unrepeatable examinations for the correct diagnosis of the cause of death.

Four cases of sodium nitrite suicidal ingestion: A new trend and a relevant Forensic Pathology and Toxicology challenge

Sodium nitrite (NaNO₂) is an inorganic compound commonly used as a food additive, antifreeze admixture, and fertilizer. Its toxicity mechanism is mainly represented by the oxidation of ferrous iron to ferric iron of one of the four heme structures in haemoglobin with the onset of methaemoglobin. The mechanism of death by sodium nitrite toxicity is severe hypoxia. We present four cases of suicidal sodium nitrite ingestion that closely occurred within a two months-period. Self-poisoning with sodium nitrite actually represents an increasing trend in nitrates' related deaths. In order to reach a precise diagnosis of NaNO₂ intoxication, a complete toxicological analysis should be carried out including not only MetHb blood levels but also nitrites and nitrites in standard or alternative matrices as a routine procedure. Autopsy should be carefully performed to detect common indicators of hypoxia or more rarely evident typical by themselves-non specific signs of sodium nitrite toxicity. Suicidal manner of death should be carefully considered when circumstantial data support that ingestion of large amounts of NaNO₂ occurred as a consequence of a self-injurious behaviour. Relevant informations include victim's previous Internet or book researches about paths to follow to commit suicide with sodium nitrate, employment and past medical history, with strong regard to psychiatric diseases as well as eventual taking psycotropic drugs. Finally, an accurate integration of autoptic and toxicological results with circumstantial data is necessary to make correct diagnosis of death due to acute respiratory failure secondary to suicidal sodium nitrite ingestion.

Suicide attempt using sodium nitrite ordered on the internet: Two case reports

RATIONALE

Sodium nitrite is a potent oxidizing agent that impairs oxygen transport and delivery through methemoglobin formation. Clinical manifestations are known to induce methemoglobinemia, dysrhythmia, hypotension, and even death. While accidental intoxication of sodium nitrite by contaminated water and food has previously occurred, there has been a substantial upsurge in suicide intoxication in recent years.

PATIENT CONCERNS

We present case reports of 2 patients who attempted suicide by sodium nitrite after ordering a "suicide powder" on the internet market. They were brought to the emergency department after attempting suicide by ingesting sodium nitrite. They experienced dyspnea, cyanosis, and mild nausea.

DIAGNOSIS

Based on their history and blood tests, methemoglobinemia was initially diagnosed.

INTERVENTIONS AND OUTCOMES

The patients received methylene blue antidotal therapy in the emergency department. The patients were discharged after neuropsychiatric evaluation and treatment for mental illness, suicidal ideation, and suicide attempts. They informed us of how simple and easy it was for them to buy sodium nitrite for suicidal purposes.

LESSONS

With widely shared information on the usage of sodium nitrite for suicide and the absence of proper regulation, the incidence of acute poisoning will increase. This increases physicians' chances of encountering unexplained cyanosis and methemoglobinemia. Clinical suspicion of sodium nitrite intoxication is warranted in cases of unexplained cyanosis or methemoglobinemia. We want to highlight how simple and easy it is to buy sodium nitrite for suicidal purposes.

Increasing use of sodium nitrite in suicides-an emerging trend

Sodium nitrite (NaNO₂) is a compound with broad practical applications in food preservation, automotive maintenance, and animal control. Sodium nitrite is also potentially fatal when ingested, as it interferes with the ability of red blood cells to transport oxygen. While incidents of accidental consumption have been reported in the literature, case reports of sodium nitrite being used as a pharmacological suicide agent are becoming more frequent. Therefore, a study was undertaken to evaluate trends in sodium nitrite deaths in South Australia between 2000 and 2019. All cases of fatal sodium nitrite ingestion were identified in the Toxicology database and autopsy reports at Forensic Science SA (FSSA). Ten cases of fatal sodium nitrite ingestion were identified, with the rate of cases increasing significantly over the study period (p > .001). Of the ten deaths attributed to sodium nitrite toxicity, eight were male, and two were female. The age range of decedents was 22-74 years (mean 51.9, SD 21.1), 22-74 years for males (mean 58.4, SD 18.2) and 23-29 years for females (mean 26.0, SD 4.2). Males (80%) and those with a history of depression and/or suicidal ideation (70%) were over-represented within the study population. While autopsy findings were generally consistent with the literature, scene findings emphasized the accessibility of sodium nitrite to the general public. This study highlights both a significant increasing trend in the use of sodium nitrite in suicides and important analytical limitations in the evaluation of suspected cases.

Fatal methemoglobinemia: A case series highlighting a new trend in intentional sodium nitrite or sodium nitrate ingestion as a method of suicide

Unintentional exposure to nitrite- or nitrate-containing toxic salts is a recognized cause of acquired methemoglobinemia (MetHb). This systemic alteration of the blood can be fatal if not recognized and treated promptly. The intentional ingestion of sodium nitrite (NaNO₂) or sodium nitrate (NaNO₃), causing MetHb, is an uncommon and recently identified method of suicide, with the first reported case in the literature occurring in New Zealand in 2010. In this case series we present 28 cases of sudden death of individuals with evidence of MetHb and/or toxic salt ingestion, occurring in the Province of Ontario, Canada, between the years 1980 and 2020, inclusive. Of the 28 deaths in our case series, 25 showed evidence of intentional ingestion of sodium nitrite or sodium nitrate salts. Our year-over-year data demonstrated this is an increasingly used method of suicide in our provincial population, with the majority of cases occurring in the final two years of our study. Postmortem detection of MetHb is typically established via screening techniques such as scene evidence suggesting fatal consumption of a toxic salt in addition to the characteristic grey-purple lividity observed upon the body. The diagnosis can be established via postmortem blood testing demonstrating elevated methemoglobin saturation. Additionally, we have confirmed that postmortem MRI in cases of MetHb demonstrates a T1-bright (hyperintense) signal of the blood; both within intracardiac blood on chest MRIs and postmortem blood samples in tubes.