In orbit there is still the significantly protecting effect of the Earth's magnetic field, which deflects much of the heavy ion radiation. This more massive radiatiom has different mechanisms of damage, and we're finding that it is likely more damaging in many contexts. So all-in-all, the space station ends up being a minor simulation of the much harsher interplanetary environment. I have several theories about how musk's team intend to solve this issue, mostly talking about surrounding the crew quarters with water. That being said, this problem is still largely unsolved and remains one of the biggest barriers to interplanetary human spaceflight.