Here's a better reference,
the National Toxicology Program analysis on BDO. It's a very extensive study where they fed rats, mice, rabiits, etc very high levels of BDO daily and measured changes in their physiology... even feeding preagnant mice etc. as well as collecting all the literature on human usage of BDO as a prodrug for GHB. They note that any toxic effects in animal models to the liver are
very minor, only present at incredibly high daily doses, and yet still are not statistically significant. Also, when administered to humans,
BDO is instantaneously converted to GHB as judged from plasma levels, so there is no reason to believe it has any unique metabolites that effect its toxicology - BDO simply doesn't hang around at all, it really is a prodrug. And when taken orally you'd expect even
more metabolism to GHB, not less!
NTP report said:
This conversion occurs rapidly; following intravenous injection of 1,4-butanediol in humans, the plasma concentration-time profile of y-hydroxybutyric acid as a metabolite is nearly superimposable over that obtained after intravenous injection of y-hydroxybutyric acid as the parent (Vree et al., 1978).
So when I hear anecdotal reports of liver damage from polysubstance users that just happen to also use BDO of unknown pedigree (it's used in plastic synthesis... there are both purer "reagent" and less-pure "technical" grades and the specification for purity is somewhat looser for the latter) it just somehow does not provide a rigorous argument against the safety of pure BDO. For all I know these people could also be ingesting mystery stabilizers, or production impurities, or even possibly consuming BDO mixed with plasticizer or something nefarious. Or binge drinking, or whatever else. The boogeyman of "BDO causes liver damage" has just not proven to be true with my experience.
I've messed with it on a daily basis for a while some years back and have had absolutely no ill effects, nor has anyone I shared it with.