Chemical suicides have figured prominently throughout history, mostly in the form of cyanide poisoning. High ranking members of the Third Reich — Joseph Goebbels, Heinrich Himmler, and Hermann Göring among them — used cyanide capsules to evade a hangman's noose. Members of the Sri Lankan Liberation Tigers of Tamil Eelam wore cyanide vials around their necks with the intent of ingesting their contents if captured by government officials.
But within recent years a cheaper and more easily effected means of chemical suicide has emerged: hydrogen sulfide (H2S).
Easily produced through the mixing of common laundry detergents, hydrogen sulfide smells like rotten eggs in low concentrations. At higher levels, the colorless and flammable gas can irritate mucous membranes and cause headaches, dizziness, and even memory loss. When concentrated at 50-400 ppm, H2S can induce coughing, breathlessness, nausea, vertigo, and vomiting. At 700 ppm, two breaths can cause immediate death.
Since 2007, Japan has experienced a statistical spike in chemical suicides using hydrogen sulfide, with some 500 people choosing to end their lives using the gas in the first six months of 2008 alone.
Domestically, there have been relatively few instances of chemical suicides. But the presence of online "how-to" manuals and growing numbers of U.S. incidents suggest that may soon change: