Medical dose? Desoxyn doses are like what, 5mg oral? 10mg oral? There is no way in hell that ANY recreational user is taking doses like that, one decent hit off the pipe (assume .1g loaded into the pipe total) is gonna be worth triple that especially considering increased bioavailability, the only possible way the blood levels would be that low is if they were indicative of prior use, and I'm pretty sure they can tell if the person was intox vs. just dirty by the metabolites.
Also I looked at those blood level charts for Fentanyl with my own dicks for eyes, and the relevant comparisons to DUI levels. Are you trying to fuck with me? I distinctly recall that Bananafloyd's levels were at minimum above average, if not in the upper third. I even made a rare pro-nigger argument that high blood levels aren't great determinants of death by overdose, because junkies can be insanely tolerant (Fentanyl specifically causes incredible snap tolerance). You're gonna have to post the relevant charts faggot, because I don't believe you.