U235 will never be safe for humans, it is a toxic heavy metal. It can cause damage to the brain, nervous system, kidneys, and other body organs if taken internally. If you mean from radiation. It is not an external radiation exposure hazard. It decays by alpha emission. Alpha radiation can’t even penetrate the dead layers of your skin.

A sheet of paper would also shield it. It could be an internal radiation hazard, but the uranium is more toxic to the body than the radiation if it gets inside of the body.

This is a handful of new unused enriched U235 fuel pellets for use in a nuclear reactor. It’s not a good idea to hold them in your bare hand but you don’t really want to handle lead with your bare hands either. Lead is also a toxic heavy metal. Sorry to all the fisherman out there, and those old enough to remember leaded gas, or when they put lead in paint.

Uranium does eventually decay to lead. For that matter everything with an atomic number higher than 118 (bismuth) eventually decays to one of the 3 stable isotopes of lead, Pb206, Pb207, or Pb208.