10 Chemicals You Really SHOULD Be Scared Of

And finally, we return to another plant poison. We don't often think of it as such, despite the fact that it's implicated in hundreds of thousands of deaths every, single year.

It is, of course, nicotine.

I might be cheating a bit with those figures, since it's not the nicotine itself that's the direct cause of death, but the smoke. However, no one would persistently set fire to a small tube of paper and suck the resulting smoke into their lungs if it wasn't addictive and, on that charge, nicotine is most definitely guilty.

Still, nicotine is a poison, and a nasty one at that. As little as half a gram of pure nicotine can kill an adult. However, even the most determined of chain smokers would struggle to kill themselves by poisoning as it would take over 500 cigarettes in a short period of time.

Nicotine likes to stick to acetylcholine receptors, and at toxic levels can cause muscle contractions (including irregular heartbeat) and respiratory paralysis. Confusingly, it can act as both a stimulant and a relaxant at the same time, thanks to the really quite astonishingly long list of chemical messengers it causes the brain to release into the body. Ultimately, in both mammals and insects, it kills by paralysis – screwing up the nervous system so much that everything simply shuts down.

People who grow and harvest tobacco need to be careful. Nicotine is readily absorbed through the skin (hence nicotine patches) and regularly handling the wet plants can cause an illness known as Green Tobacco Sickness. This causes nausea, headache, dizziness, muscle weakness and fluctuations in blood pressure and heart rate.

Nicotine poisoning has an interesting part to play in the early foundations of forensic science. In Belgium, 1850, a pair of socialites, the Comte and Countess de Bocarmé, were counting on a large inheritance when the Countess’ father died. But to their annoyance he left most of his money to his son. So the Comte and Countess invited him to dinner and doused him with pure nicotine. They believed they would get away with it as, at that time, there was no way to identify nicotine in a dead body.

The magistrate, however, was determined to get to the bottom of the crime and so took the problem to the Belgian chemist Jean Servais Stas. He patiently started work with organ tissues from Fougnies’ body and, after three months, found a method which allowed him to extract the nicotine from the tissue. The Comte de Bocarmé got his well-earned comeuppance and this technique, called the Stas-Otto method, is still used in toxicology today.

And let's not forget the frightening statistic that tobacco use is estimated to have killed 100 million people in the 20th century. That's considerably more than all deaths in World Wars I and II combined. Nicotine surely deserves its place as the number one chemical you really should be scared of.