opiates are very safe drugs when used properly. they, in and of themselves, do not cause shorter lifespans, as you said yourself:
Controlled studies to date show they don't shorten lives when used properly.
Those are your words, which I agree with. users of opiates
do have shorter lifespans, true, but it's a correlation, not causation except for in the rare case of a fatal OD. that's why the bolded part of this first sentence quoted below is false:
Abuse problems are far more likely with these compounds than most clinical drugs and that leads to shortened lives BECAUSE of the compounds/drugs. Are the drugs biologically toxic? No...
and is contradicted not only by the sentence immediately following it, but by your aformentioned quote regarding controlled studies as well.
Your concern seems to be that the abuse potential for the synthetics drugs makes their use potentially unsafe. That I agree with, but that is not the same as saying the substance itself is dangerous. That's saying it's misuse is dangerous. Those are two different things. This is as good as I can articulate it.
How in the world does society fix the problem with heroin?
There are three main ways, in no particular order, to mitigate deaths/injuries associated with heroin abuse and the secondary crimes related to its procurement: education, decriminalization, and regulation. You could add a fourth about changing attitudes as a society (for example sherlock holmes and freud using cocaine was not a problem back then, but it is now....why? what changed?), which is really a pre-req to the other three things. Human civ is 10,000 years old, and we got along just fine smoking opium bascially the whole time. synthetics and needles have increased the danger for negative outcomes with opiate use, but the danger is not intrinsic to the drug, and it's really a minuscule problem when compared with the other problems we have the U.S., and the way you fight that is, primarily with education.
current policies are not just semi-effective, they actually exacerbate the problems, and that's why prohibition will continually fall out of favor. Most things, most of the time, cannot be successfully prohibited. History has really been clear on this, so to address this "problem" you need to be more creative.