If asked what the deadliest drug or substance is, you might be able to manage the correct answer after a few guesses. As for the most dangerous one? That's a lot harder to figure out without some serious number crunching and the result isn't anywhere near as exciting or mysterious as you might think.
For the definitive answer, AsapSCIENCE has condensed the discussion into a tight, four-minute video that clarifies the difference between "deadly" and "dangerous". As previously mentioned, most deadly isn't hard to find out.
The median lethal dose (LD50) of botox is 0.00000007g, enough to kill a 70kg person. By comparison, you'd need 13g of caffeine to achieve the same effect... in this case, death.
Most dangerous, on the other hand, requires deeper exploration, as the video explains:
However, "most dangerous" doesn't always mean "most lethal". In the UK, a group of experts decided to look at how much "harm" the most common recreational drugs cause using 16 parameters, including types of physical, psychological and social harm.
This study concluded that heroin was the most dangerous, given its fast absorption, multiple methods of ingestion, highly addictive qualities and of course, excruciating withdrawal symptoms. Even with these powerful qualities, it still pales in comparison to another drug -- alcohol.
In many ways, it's not much of a surprise, but how researchers came to this conclusion is rather interesting and explained well in the video above (or below, if you like clicking).