Which statement about hydrogen cyanide is true?

• A. High lethality with no antidote
• B. Not an industrial product
• C. Low to moderate lethality and some drugs mitigate effects
• D. Not produced from banned chemicals

Answer: (C)

Hydrogen cyanide is an extremely toxic chemical whose danger can be significantly reduced with prompt antidotal treatment. It blocks cellular respiration by inhibiting mitochondrial cytochrome oxidase, so even with oxygen delivered to the tissues, cells can’t use it, leading to rapid hypoxia and potential death. But there are effective antidotes and supportive care that mitigate this effect. Treatments like hydroxocobalamin, nitrites with thiosulfate, and rapid administration of oxygen bind or neutralize cyanide, allowing mitochondria to resume functioning and improving survival chances. That combination of rapid onset toxicity with proven treatments makes the statement about having low to moderate lethality when treated with some drugs the best choice. The other statements misrepresent its industrial use, the existence of antidotes, and the variability of lethality, which are all important context for understanding how exposure risk and outcomes can change with proper care.