Actually, at least in the case of MDMA, the adulterants are, in fact, the issue:

"Testing kits are needed because many pills sold on the illicit market as "ecstasy" are fake and do not actually contain MDMA. Fake pills often contain drugs more dangerous than MDMA, including dangerous drug combinations, or drugs that are especially dangerous when mixed with MDMA (as often happens if someone takes more than one pill in a night)." ----from http://www.dancesafe.org/testingkits/

"Working in such conditions requires that a person be able to check himself, evaluate his condition in relation to the crew and in relation to mission control and be able to correct himself," said Boris V. Marukov, the experiment's director and a former crew member on the International Space Station."

Translating Ice Cube lyrics from Russian is terribly complicated.