They're researchers. They need to know the exact amount. Simply blowing marijuana smoke into the lungs of the mice makes for a poor study.
"They then began giving half of these mice daily injections of about 250 micrograms of synthetic THC."
Probably equivalent to a human smoking 6,000 marijuana cigarettes per day. But count on the dopers to claim smoking pot cures cancer.
I think marijuana's active ingredients hold a lot of promise. Of course you're right about the amount given the mice. They do that with a lot of substances they're testing. Remember red dye #2?
Marijuana has been shown to help glaucoma, macular degeneration, and nausea caused by many things including chemotherapy. I believe that God put these substances on earth for a reason. I keep voting to legalize, the rest of us do, it passes, then the courts tell us we're stupid and invalidate our vote. I don't smoke pot.
Btw, just make brownies. That way you don't need to blow pot smoke directly into the mouse's lungs ;-)