tl;dr; version: "Walter Cronkite, a revered American journalist, told us in 1977 that Plutonium is the most dangerous substance known to man. That statement was widely believed, and widely repeated. But that statement is false. Unless you are really stupid about the critical mass, Plutonium has a quite innocuous MSDS ( https://en.wikipedia.org/wiki/Safety_data_sheet ), and is almost impossible to poison a person with."
The Real Problem: Walter Cronkite's statement was true, but in a big-picture contextual and somewhat poetic sense. The fraction of humanity with any reason to care about the MSDS safety of plutonium is ~0%. The fraction of humanity living in (in 1977, and often since) a world which seems threatened by a hellish large-scale nuclear war is ~100%. Making the "MSDS Argument" to people in the latter group is often a good way to convince them that you're an obnoxious and uncaring little jerk, eager to show off that he read a science textbook at school.
Analogy: Read a bit about the lethality of WWI battlefields in Europe, how many millions died on them, and how traumatized European society was by that war. Imagine that someone from that era claimed that the most dangerous substance known to man was the special steel alloy used to make artillery gun barrels and machine gun barrels.
Or the "WW1 technology" angle, the example that comes to mind is the invention of the Haber process for ammonia production. This allowed mass production of fertilizer (saving many from starvation) but also enabling mass production of explosives (again with many peaceful civil applications) which enabled industrial scale wars like WW1.
The Real Problem: Walter Cronkite's statement was true, but in a big-picture contextual and somewhat poetic sense. The fraction of humanity with any reason to care about the MSDS safety of plutonium is ~0%. The fraction of humanity living in (in 1977, and often since) a world which seems threatened by a hellish large-scale nuclear war is ~100%. Making the "MSDS Argument" to people in the latter group is often a good way to convince them that you're an obnoxious and uncaring little jerk, eager to show off that he read a science textbook at school.
Analogy: Read a bit about the lethality of WWI battlefields in Europe, how many millions died on them, and how traumatized European society was by that war. Imagine that someone from that era claimed that the most dangerous substance known to man was the special steel alloy used to make artillery gun barrels and machine gun barrels.