If everyone thought it was harmless, why wasn't it conducted on college students, the usual specimen of choice for harmless experiments? Was it just a coincidence that the researchers decided to experiment on the most powerless and defenseless subjects they could find?
This is MIT, not Mengele's Auschwitz. Radioactive tracers are injected into the blood streams of millions of people every year for PET and CT scans, of all ages, which is far more harmful than radioactive tracers in food.
That doesn't answer the question at all. It kinda just assumes that the question isn't really interesting because of course MIT isn't like Auschwitz, even in the instance where it kinda is.