Scoville = The unit used in scouters to measure spicyness. 5000 scovilles is incredibly bland.
If what is informed is correct, 1.000.000 scovilles it can actually HURT your tongue, and pure capsicain itself is about 16 million.
Some poisonous plants have a capsicain-polymer-based latex which has some BILLIONS of scovilles. So, if you're unfortunate to get one of those in your mouth, you'll be too busy trying to close the actual hole it punched through your tongue (seriously) while feeling you're drinking molten lava, instead of getting some antitoxin.