A third chemical – cocaethylene – builds up in the liver over a number of years among those who mix the two drugs. And this is now having major health consequences

"I first took coke when I was 18 and at university. I remember two friends who did chemistry told me I should get really drunk first because it would mix into this new chemical in my blood and make me even higher," a 30-year-old woman who works in publishing told the Observer yesterday.

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