The science and health industry’s perception of cannabis or use in 1967 was quite different than it is today. Let us not forget that cannabis fueled 1967’s “summer of love” in San Francisco and then it was called "marijuana" and a joint was called a "reefer cigarette" by parents, teachers and clergy. Also remember that CBD soap had not been invested yet.
50 years ago, it seems that scientists could only conceive of THC consumption and ingestion through smoking. They used terminology for the single hit from a marijuana joint or pipe as a “single dose” as opposed to a single “hit” or “rip” or “tug” or… whatever.
Check out this excerpt from Science News 50 years ago.
Confusion over effects
“No one knows whether chronic marijuana smoking causes emotional troubles or is a symptom of them.... This dearth of evidence has a number of explanations: serious lingering reactions, if they exist, occur after prolonged use, rarely after a single dose; marijuana has no known medical use, unlike LSD, so scientists have had little reason to study the drug…. Also, marijuana has been under strict legal sanctions … for more than 30 years.” – Science News, October 7, 1967
Please note the irony of the use of the word “chronic”. At least they got something right… sort of. Global warming?