Hello Ask Historians!

Yesterday, on the thread about the Navajo Code Talkers, I got into the conversation about the Atomic Bomb and comparing it to the fire bombings of Japan and which weapon was more devastating.

I made the remark that no one knew the long term radioactive effects of the bomb in terms cancer and radiation sickness when it was first dropped, and that initially the idea of a Single bomb being that devastating was a bigger deterrent than the radioactive component of the bomb long term. A couple of people questioned that remark, and rather than arguing, I wanted to find out the answer here.

My understanding is that had the US known the radiation component of the bomb, they would have protected their scientists at Los Alamos better. (I have heard that most died of cancer some years later)

So... My question is... did the US know of the Radiation ramifications of the Atomic Bomb prior to using it on the Japanese, and was that knowledge known by Japan and other nations as well when the bomb was dropped?

Thank you!