:) what I meant was...
Hydroden sulfide is common in nature, there are caves that will kill spelunkers without protection due to the high levels of hydrogen sulfide. HS is used commonly, it is mixed with natural gas to give it a noticeable smell...
Nearly every compound used in our world has been extensively tested on rats to see what the lethal dose is, I just find it odd that this effect wasnt noticed previously, if only by accident- it makes me wonder if there were factors needed to make it work that were not mentioned in the article.