Keyword search "Marijuana". There are over 25,000 scientific journal articles that cite the plant.

"Tylenol" - 20,550 citations
"ibuprofen" - 12,491 citations
"Ritalin" - 8,192 citations
"hydrocodone" - 948 citations
"Adderall" - 201 citations

Other drugs have far less literature and are prescribed to our kids every day.

Surprising Facts about Cannabis Research (video)
http://www.youtube.com/watch?v=728VTpb8xJQ