A reader writes:
One that was not included in the American Scientist article you quoted was caffeine. I found references for an effective dose of 3-9 mg/kg. The average American male weighs 86.8 kg, making the effective dose 260mg - 781mg or so. Deaths have been reported due to caffeine overdose in individuals that consumed 10-20g of caffeine. This is a ratio of lethal to effective of about 100:1 or less. Say around the same ratio as Kava Kava. This is for a drug I'd guess the majority of Americans consume daily.
Can you imagine how great it would be if Starbucks went into the marijuana business? They'd make a fortune on the raspberry scones. And they wouldn't be peddling a product as addictive and toxic as caffeine.