Slate.com hat einen interessanten Artikel zum ökologischen Fussabdruck verschiedener Drogen. 

Um es kurz zu machen, die grössten Verschmutzer:

1. Ecstasy / Amphetamin
2. Kokain
3. Heroin
4. Cannabis

Die interessanten Ausführungen gibts in besagtem Artikel: The greenest High: Which illegal drug is best for the environment?

"Let's say I were the type of person who would go to a party where an assortment of recreational drugs were being used. Would it matter, so far as the environment goes, which one I took?

Let's be frank: Most highs for you are kind of a downer for the planet. The conditions under which illegal drugs are produced make it impossible for the government to enforce any sort of clean manufacturing regulations, and the long-standing "War on Drugs" inflicts its own environmental damage. (Think of the RoundUp herbicide sprayed on 120,000 hectares of rural Colombia each year.) There are some ways to measure the eco-credentials of various narcotics, though. To understand how various drugs affect the environment, we need to take a close look at where each one comes from and compare the ways they're harvested or synthesized. [...]"