Bagel Libre
← Occupational toxicology & industrial hygiene

Asphyxiants — hydrogen sulfide & cyanide

Chemical asphyxiants other than carbon monoxide: hydrogen sulfide and cyanide. Hydrogen sulfide: the knockdown effect, cytochrome oxidase inhibition, carotid body stimulation and respiratory arrest, nitrite treatment, and long-term neurologic sequelae. Cyanide: cellular mechanism of toxicity, lactic acidosis and elevated venous oxygen saturation, retinal arterialization, antidotes (hydroxocobalamin, sodium thiosulfate, nitrites), fire-gas exposure, and the bitter almond odor.

Sodium thiosulfate is a long-standing antidote for cyanide poisoning. By which mechanism does it facilitate the detoxification of cyanide in the body?

A.Direct chelation of cyanide ions to form a stable cobalt-cyanide complex.
B.Acting as a sulfur donor to accelerate the rhodanese-catalyzed conversion of cyanide to thiocyanate.
C.Inducing methemoglobinemia to provide a pool of ferric iron for cyanide binding.
D.Binding to the carbonyl groups of pyruvate to form non-toxic cyanohydrins.