Although it is difficult to establish a ranking of stenches, most experts agree that the most unpleasant odor in the world is that generated by mercaptan . It is a sulfur compound that generates decomposing matter, and that in its pure state emits a "stink" that can make us feel really sick. Those who have smelled it compare its stench to that of rotten eggs or well-worn socks.
However, this fetid aroma has also turned out to be useful: adding a derivative, methyl mercaptan , to natural gas ensures that this odorless fuel can be detected by human smell , warning of possible leaks. Hence, it can be said that mercaptan has also saved many lives.
Mercaptan is also added to reactor fuels and pesticides.
