I remember that at my University, they had the old CSIRAC computer, which was one of the older computers in the world.
For its main memory it used to use mercury delay lines. These were large tubes of mercury, with a pulsator at one end, and a sensor at the other. Stuff to be "stored" in memory was pulsed in at one end, and the pulses would take some time to travel to the other end, where they were sensed, and if the CPU needed the information at that time, it would use it, otherwise the information got cycled back. The computer had multiples of these lines, and they would slowly leak mercury, with the operators having to come in on a morning and "mop up" small puddles of mercury from the floor.
One of our University lecturers used to work in the room where the computer was during his younger years. He was the crankiest s.o.b. you could ever hope to meet.
When Coca Cola first came out, one of its main ingredients was Cocaine, obtained from the "coca" plant, hence the "Coke" and the "Coca" derivations of its name. Santa Clause was also never really perceived as a fat man dressed in red & white before a wildly successful 1930's Coca Cola advertising campaign.
I guess what I'm saying is that people's perceptions of the dangers of various substances changes over time, and with experience. Cocaine and mercury, which were once deemed to be not so harmful, have a completely different perception nowadays.
