The effects of direct contact with radiation can be truly horrible. Burnt skin, radiation sickness, cancer are just a few of the things to happen if someone comes into direct contact with an irradiated element. But who among us didn’t dream of getting exposed to just a tiny bit when we were children? Because that was the easiest way we could conceive of that would give superpowers like Spider-Man and the Hulk had? You can thank Stan Lee for that.
Radiation was an element that Lee used several times in the early years at Marvel. The Fantastic Four were given their powers from being doused in cosmic rays while they were in outer space. Peter Parker was bitten by a radioactive spider. The Hulk was the victim of a gamma bomb blast. Even a street-level hero like Daredevil got his powers from being in contact with toxic waste, even as it took his eyesight. So why did these heroes have such similar origins? It all goes back to WWII and the cold war.
During the years following the second world war, tensions between the United States and Russia were getting more and more frigid. Thus, the "cold war" ran for generations before the wall dropped in the late 80s. In the 50s and 60s, everyone was afraid that there would be a nuclear bomb going off somewhere nearby, or they would get sick from radiation poisoning. Students at the time were taught to hide under their desks in case of a nuclear detonation.
Those fears infected popular media as well. Cosmic horror and sci-fi films were all about the radioactive monsters and giant insects, lizards, and even giant radioactive bunnies. Lee, being the man he was, was able to tap into this fear to get the audience to connect with the characters. After all, who would want to be near toxic waste? Even if you got superpowers from it, you'd still be blind, if it doesn't' kill you outright.
Despite the incredible powers that Lee imbued his characters with, there was always a streak of humanity that was lacking in DC Comics at the time. To paraphrase Uncle Ben, with great power comes great cost. Daredevil may have gotten four senses heightened, but it came at the cost of his fifth. Peter Parker got his powers from a spider, but it wasn’t until he indirectly caused his uncle’s death that he became a hero. And, of course, both the Hulk and the Thing are literal monsters. Stan Lee was able to tap into this national zeitgeist of fear of radiation and use it to his advantage. By irradiating his heroes, he showed that powers do not make the hero; the character’s humanity does.