DU is dangerous because of its Radiation. The so called Alpha Radiation does not Penetrate very well and it has not a significant reach, you can cut off Alpha Rays with a simple piece of Paper.
Problem ist when alpha radiating material gets into your body through any way, e.g. cuts in the palm. Then it does enriche at your bone marrow, depleting production of red blood cells.
Thats why it is to worry about this in cases of accidents with it (burning over 600 degees celsius effects it to spread, a chain reaction in any case is very unlikely due to missing of a moderator), beta and gamma radiation are at insatisfying [low] numbers anyway.
[edited]
Last edited by Sokol; 17th Dec 2017 at 17:16.