In November 2019, I interviewed Canadian senior scientist Dr. Ernest Small regarding his pinnacle—and paramountly influential—1971 book The Species Problem with Cannabis. It was this book that established the North American standard of 0.3% tetrahydrocannabinol (THC) to separate hemp and cannabis. The European Union has adopted an even more strict limit of 0.2% THC or lower to qualify as hemp in that region of the world.
