The pH is not 3...that is for sure! GBL is neutral pH. As the other guy said, lactone is a solvent and that is why it can dissolve certain types of plastic (if recycle you know the different type HDPE, HDPP etc.)
Why do I say that lactone is shit to use by itself? Because I used it for several months all the time (like you are not suppose to do) when I stopped using the stuff, I went through some SERIOUS withdrawls! Thought I was going to die.
I have also used GHB the same way....daily and for months on end. The withdrawls are not near as bad! There is something different that your body does when it process Lactone vs. GHB. They all enter into glycolysis but at different places in the pathway....there is a possible by-product that results from this...(not sure...this is just my guess)
So to answer your question, I base my info off of first hand knowledge. I have been using it for YEARS and I can tell you that Lactone has BAD side effects....you might not notice them at low amounts but still...there is something different about it.