Hydrogen cyanide is a colorless and poisonous gas. It is made up of hydrogen, which is a common element, and cyanide, which is a toxic compound. It can harm living organisms if they breathe it in or come into contact with it. Full definition
The team observed specific microwave emission from hydrogen cyanide molecules (HCN) and formyl ions (HCO +). (sciencedaily.com)
Meanwhile, hydrogen sulfide, which would have been released in huge amounts by volcanic eruptions, would have mostly stayed in the atmosphere, as the molecule is relatively insoluble in water, and therefore would not have had regular opportunities to interact with hydrogen cyanide. (sciencedaily.com)
In the chemical toxin category, perchlorate (a naturally occurring chemical, but also a man - made contaminant stemming from production of nitrate fertilizer with certain types of ore serving as the nitrogen source) and tobacco smoke (which contains hydrogen cyanide that can be converted into thiocyanate) are well - researched examples of chemical toxins that are considered goitrogenic because they can interfere with thyroid function. (whfoods.org)