10 Chemicals You Really SHOULD Be Scared Of
3. Phosphine
In the pilot episode of Breaking Bad, down on his luck chemistry teacher Walter White makes, or at least says he's made, phosphine gas, which he uses to dispatch some rival gangsters. The chemistry may be a little bit questionable, but one thing is for sure: phosphine gas really is nasty stuff.
Phosphine is a simple molecule, made up of a single phosphorous atom attached to three hydrogen atoms. The molecule itself looks very similar to ammonia, but it's far less pleasant. The gas is denser than air and will collect in low-lying areas. Why is this a problem? Well, quite apart from its toxicity it can form explosive mixtures with air, and it can also self-ignite. Yikes.
It's used in pest control, although indirectly. As I've already suggested, phosphine itself is a gas at room temperature, with a boiling point of -88 Celsius. It is used as a fumigant, but there's that whole self-igniting thing. But there's another way to use it: there are several metal phosphide compounds which will release phosphine in contact with water. Or in contact with the contents of a rat's stomach. Zinc phosphide is one such compound, and pellets of it can easily be left in places where rodents will find it.
Rats, curiously, don't have a vomiting reflex. For this reason, zinc phosphide and similar substances are usually sold mixed with an emetic compound, making the poison safer for humans and other domestic animals (dogs and cats, for example) who might accidentally chance across it.
The list of symptoms of phosphine poisoning is really quite extensive. It causes nausea, vomiting, abdominal pain, diarrhoea, thirst, breathing difficulty, muscle pain, chills, stupor and fluid on the lungs. And, as if that weren't enough, it smells revolting, too. It apparently has odour of decaying fish or garlic at even the lowest levels. This might be a useful warning - except that higher concentrations cause olfactory fatigue, which means you stop smelling it after a while.
So if you smell rotting fish, but then the smell goes away - don't take any chances. Get out of there.