From the second link-
the danger in heroin is u cant trust street heroin, but it really is almost identical to morphine, if someone had say pharmaceutical grade heroin, clean syringes, chipped with it not shot up 5 times a day. Then yes its believed to be quite safe its all a matter of the quality and the users ability to judge there tolerance. i read a very well researched article on the safety of it a while back, and it said the junkie lifestyle is really what makes it dangerous, it even mentioned that a founder of Johns Hopkins was a morphine addict for a very long time and died a natural death with nothing wrong with his organs and what not on the autopsy, and like a said above morphine and heroin are alot alike. Ive heard the only real problems come from the way it effects your brains ability to perceive pain making it more intense, and its effects on the brain are even less than that of high doses of oxycontin.
Read more:
http://www.drugs-forum.com/forum/showthread.php?t=36658#ixzz2kwEKV3n7