This
http://www.nature.com/articles/srep29901
might influence decisions on future long term stays in spacey conditions.
Health seems to be in danger when leaving earth's magnetosphere. Of course, the database is thin.
From the Abstract: " The results demonstrate that space-relevant irradiation induces a sustained vascular endothelial cell dysfunction. Such impairment is known to lead to occlusive artery disease, and may be an important risk factor for CVD among astronauts exposed to deep space radiation."