In 1945 and 1946, there were two criticality accidents at Los Alamos National Laboratory that resulted in scientists being exposed to massive, ultimately fatal levels of radiation.
Both accidents occurred because of a disregard for safety protocols and a cavalier attitude toward hazardous materials that would be considered shocking by modern standards. However, as far as I can tell, at the time of these accidents, there had never been a severe, acute case of human radiation poisoning.
How much was known about the effects of radiation poisoning on the body in 1945? Was the lack of caution when handling plutonium a result of ignorance about its effects, or simply bravado/carelessness on the part of individual scientists?
As a further question, how did these two accidents—and the massive number of radiation victims of the atomic bomb—inform and influence treatment of radiation poisoning?
Thank you for your time!
Well, it should be noted that prior to the deaths of Daghlian and Slotin, there were many people who suffered from and died of radiation poisoning — at Hiroshima and Nagasaki. This was studied as carefully as the Japanese physicians tending to them could do (for the acutely fatal ones), and later the long-term effects were studied by the Atomic Bomb Casualty Commission. Susan Lindee's Suffering Made Real looks at this history quite closely.
But you are right that in the US, they had no prior experience with acute radiation syndrome prior to Daghlian, and they certainly studied the course of their illnesses quite closely (they are documented in excruciating detail in Louis Hempelmann, "The Acute Radiation Syndrome: A Study of Nine Cases and a Review of the Problem," Annals of Internal Medicine 36, no. 2, Feb. 1952), along with those who were in the rooms with them (who received lesser doses).
The effects of radiation on the human body had been studied previously, though. The 1910s-30s saw several cases of chronic radiation exposure with the famous "radium girls" case (watch painters who used their tongues to wet the nibs of radium paint) as well as people like Eben Byers (d. 1932), a wealthy socialite who consumed quack radiation cures to his own demise (he caused his entire lower jaw to fall off).
These cases brought attention to the deadly side of radiation, which had already gained something of a cautious reputation in professional circles (early X-ray operators famously developed very particular forms of scarring on their hands). Robely Evans at MIT became one of the first "health physicists" who studied these effects, and it was he (and others) who were working on/with the Manhattan Project to establish safety standards for exposure to radioactivity. They did this through many methods, including animal studies and some human studies (never high dosages, but they gave terminally-ill patients plutonium to see how it passed through their body — without informed consent).
But they were very aware that high doses of radiation would be deadly, and that a criticality accident would cause that. That was not a question. Daghlian and Slotin were well aware; they had been told as much many times. They didn't call such experiments "tickling the dragon's tail" for nothing. Slotin in particular had been told that if he approached criticality experiments as "cowboy" like as he did, that he would be dead at a young age.
So like many things there were areas of ignorance and areas of knowledge. The criticality experiments were not out of ignorance, though. (Expedience, bravado, a poor safety culture — these are more plausible places to look for blame.) They definitely took advantage of these "experiments of opportunity," as with the Japanese victims, to learn about these things.
I don't know off-hand about the effect on treatment regimes, but all of this became part of the basic literature on acute radiation syndrome (the Hempelmann article in particular I cited is the core article for prognostics on it — it describes how the cases progressed, what kinds of treatments helped a bit, etc.). But I don't know how treatments have evolved.
The best single source on this stuff is Barton Hacker, The Dragon's Tail: Radiation Safety in the Manhattan Project, 1942-1946 (University of California Press , 1987). On the Human Radiation Experiments briefly referenced, see Eileen Welsome, The Plutonium Files.