Well, the question is where is the tritium. If it comes in the form of heavy water, then the biological half life is indeed short. But tritium can substitute es

Well, the question is where is the tritium. If it comes in the form of heavy water, then the biological half life is indeed short. But tritium can substitute essentially any hydrogen, and so it can also come in the form of amino acids, which have a good chance to end up in the nucleus of a cell. So especially for tritium, it can essentially end up in anything where organic chemistry is involved, which is to say everywhere. However, the general problem I have with articles about the dangers of radioactivity is, that they almost never contain enough information to actually judge how dangerous it is. It is usually easy to get a factor of 100 or more variation in the dangers of radioactivity, based on the exact contamination scenario, the precise isotope abundances etc. So even Pu is not always very bad, since PuO is almost insoluble in water, which can be used for nice party tricks [1]: [...] to eat as much plutonium as any prominent nuclear critic will eat or drink caffeine. My offers were such as to give me a risk equivalent to that faced by an American soldier in World War II, according to my calculations of plutonium toxicity which followed all generally accepted procedures. [1] http://www.phyast.pitt.edu/~blc/book/chapter13.html http://www.phyast.pitt.edu/~blc/book/chapter13.html