I've heard this before, and it seems so odd to me...that must make the manufacturing process kind of weird.
I remember an old source (not this board) offered EQ at 1,000 mg/mL, lol. I'm not sure whether it was trustworthy, but the justification for it even being possible was that the stuff really is just liquid. I never bought it, but it seems like that'd be insane to even get through a syringe...and even if the finished product is a bit less dense than water, that leaves almost no volume for a sterilizing agent.