In cancer use very short,like 8hrs.In eng use kinda 5-30yrs.btw all material can be radioactive.radiate it.its part of world i guess.its like matter and antimatter.maybe there is a lot of positive side to be study rather than just focus on the effect.who might know.

but its cool.u can kill a person with alpha partikel and leave it no trace.najibulrosmah should know this before end up with c4