That I don’t have a concrete answer on. There’s very little studies on it and if I ask questions to some people it raises suspicion. In the real world if the purity is below somewhere around 98% the batch is just rejected. But it all depends on what we’re talking about; food, oral meds, injectable, concrete testing, corrosion control, etc. I have some standards at work for 90% on a product and we accept the batch, other tests come back at 99.94% and rejected without question.
In the steroid world I’ve seen tests comeback as low as 96% for injectables and we don’t a ugl brewing. Orals the resident source had 92% for one and I’m sure they used it. As far as what is in the other x% I have no clue because I don’t know anyone that’s tested the fillers. The most logical answer is ingredients in the manufacture process that didn’t convert from whatever into the hormone they’re making. I’d be interested in seeing a source have the impurities tested for the hell of it.