If heroin was a commonly used adulterant it would be consistently appearing on reagent tests and GC/MS testing done by the authorities. Millions of pills are consumed on a daily basis and the found reports of heroin in pills numbers less then the total amount of deaths from acute MDMA poisoning. We would have read about such an issue in Microgram by now.
I would rather talk about winning the lottery as a more likely event then ever getting heroin in my pills. More to the point the completely spastic dealer that
the_ketaman quotes got caught a long time ago thus ending such shenanigans. It would be wrong to claim that heroin is used as an adulterant in most pills being sold these days, on the basis of one dealer who did it.
For the most part the vast majority of heroin dealers I've know are far too smart (even the dumbest ones) to ever bother putting smack into pills. They are far to busy cutting their shit with glucose to maximize their profits then to bother printing out thousands of pills, by hand.
2. Regarding the glass thing
"The risks of swallowing these materials depends on their size, shape and sharpness.
Small pieces can travel right through the bowel and be passed normally without problems. The bigger the person, the larger the piece that can go through. In general, narrow objects pass through the bowel more easily and smooth ones are less likely to get caught.
Sharp objects such as glass fragments would be expected to cause damage but rarely do so because of the gentle way in which the bowel handles them. Small splinters or spikes could cause perforation but this is very unusual. A small perforation rarely leads to peritonitis and usually heals quickly with any leakage contained. Small fragments may also cause a little bleeding into the bowel which can be detected on tests in the stools but serious blood loss is very rare.
Ground glass, despite its reputation in thrillers, has no serious effect on the bowel."
http://www.digestivedisorders.org.uk/content/pdfs/18 Swallowing Glass.pdf
Consequently there are two things I think we can safely suppose.
a. The vast majority of glass claims in pills are simply people who have seen crystalline shards, be it meth or any other substances (doesn't MDMA have a HCI form?).
b. That the people who in turn to propagate these rumors are either extremely high or conversely had little sleep. I can recall many times talking to dealers who had been awake for several days shooting meth and so on going on to claim things like glass in pills, rat poison on acid and all the other urban myths.
c. that glass will in the vast majority of cases pass through the gut with little to no damage.
d. that there is (as far as I know) no official report of glass ever being in pills. Sure you get the occasional cop claiming that it
could[ be in drugs but are there any official reports of this substances being found?
So in the ultra rare instances of real glass in a pill, is there anything to be worried about, no. Apart from the rare possibility of glassware breaking and the product containing said material I would say that most chemists would remove, at the very least the larger pieces of glass (a sifter would easily do it).
If your selling several kilo's of pure MDMA to a criminal gang intent on distribution you can be sure the chemist doesn't want to be accused of contaminating the product with glass of all things. You would not be a happy chappy when said gang family/friends were injured by a large piece of glass in the product.