toothpaste tube can be powerful and potentially deadly. this bomb in a toothpaste container blew off a car door, sent parts of it across the quarry in southwestern england where cnn commissioned this test with the help of sidney alford, a man who helps people understand explosives. >> i wouldn't like to be in an airplane in which that's exploded, not even a big one. >> reporter: for this test, alford used an explosive called rdx, a white crystalline powder. he mixed it with another ingredient to create a paste. he filled three-quarters with his explosive concoction, the rest with toothpaste. >> it smells and tastes like toothpaste. i have presented this in such a way that somebody giving it a casual inspection would probably pass it. >> reporter: the size of container alford used is the kind you have to place in checked baggage, but alford says two smaller containers this size, which you can carry on,