I totally believe that there have been instances where governmental actors have intentionally poisoned drug supplies, but I don't think that's the majority of c

I totally believe that there have been instances where governmental actors have intentionally poisoned drug supplies, but I don't think that's the majority of cases. Watching Vice documentaries about clandestine manufacturing and the conditions they work in, it is not hard for me to believe that the most frequent cause is just lack of will and chemistry talent in order to purify a substance. Cleaning inert cutting agents out of drugs is fairly easy because the molecules are often dissimilar. But when manufacturing drugs, there are often steps that have probabilistic products that are very similar. Hypothetical example: you end up with 99% MDMA but 1% something that is very structurally similar but has no recreational value and is cardiotoxic. These molecules are so similar that the only way to separate them are challenging and expensive: such as multiple rounds of recrystalization and chromatography. Only a tiny portion drug buyers will notice the 1% cardiotoxic byproduct (access to GCMS testing?), so there is no economic incentive to do these final expensive cleaning steps.