Deadly Combination of Formic and Sulfuric Acid: 2 Cases of Carbon Monoxide Intoxication

Background: Carbon monoxide (CO) poisoning is associated with high morbidity and mortality rates. Although accidental inhalation is the most common cause, suicide through CO from a mixture of formic and sulfuric acids is extremely rare and poses unique risks to first responders. Case presentations: Two male individuals died in their vehicles after mixing formic and sulfuric acid to generate CO. Both cases showed characteristic cherry-red or pink livor mortis and high postmortem carboxyhemoglobin levels (73% and 85%, respectively). In both scenes, labeled acid containers and enclosed spaces were present, with 1 case noting an unusual odor. Conclusions: Chemically induced CO poisoning, although rare, requires heightened awareness among first responders because of the danger of undetected exposure. Key indicators include unusual livor mortis, enclosed or taped-off spaces, chemical smells, and the presence of acid containers. Postmortem toxicology is crucial for confirming a diagnosis and understanding the cause of death.