Almost all "E" tablets are contaminated since pure MDMA can't be formed into a pill. It needs a filler to hold it together as a pill. Which is usually drugs like ket or amphetamine. Pure MDMA only comes in crystal form.
I'm not sure "contaminated" is the correct term for some of the additives. ProSolv might be found in a good quality E, and that's just a standard tablet binder.
Regardless, most deaths are still caused by contaminants.
