It has come to my attention that some statements have been made in public which suggest that uranium sticks to DNA and thus is more dangerous than a radioactive metal which does not stick to DNA. This statement has been recently repeated by Paul Langley who is an antinuclear blogger.
I would like to point out something, that while uranium(VI) does bind to DNA it also binds to carbonate. As the concentration of carbonate in the human body is so much higher than that of DNA, the carbonate will by competing with the DNA (and all the other molecules which can bind uranium) for the uranium. As a result the amount of uranium which will bind to the DNA may be much lower than would be predicted if only the binding of uranium to DNA was considered. A paper on this subject can be seen here. I think that those who like to talk of uranium binding to DNA in living cells should repeat their calculations after having taken into account the effect of carbonate anions.
If you want to see what a uranium carbonate complex looks like then please see here.
I would also like to point out that an alpha emitter does not need to bind to DNA in order to have a baneful effect. I think that the uranium binding to DNA is a bit of a red herring, one which will confuse the general public.
The length of an alpha track in water is sufficiently long (at least 50 micrometers) that the alpha particle can travel some distance through a cell. You can see a graph of alpha range as a function of energy here. I will warn you that the example of the range (in meters) of the beta particles of Sr-90 used on this latter page is misleading as the Y-90 daughter has a much higher beta energy.