In a biographical article about the life of Jeon Tae-il, Wikipedia states that
As a tailor, Jeon witnessed the horrendous working conditions in the Seoul Peace Market... Such conditions included rampant tuberculosis... and the enforced injections of amphetamines to keep sleep-deprived workers awake and to work them overtime without proper compensation.
I can't easily find any other mentions of this, but I am skeptical for a few reasons:
- Amphetamine would be a extra cost for the employer, who could probably find cheaper ways of coercing employees to stay awake
- Amphetamine pills would probably be easier to administer compared to injections
- Although drug use to increase productivity is well established across many different countries throughout history, most of the other instances of it were voluntary
Note: For the purposes of my question, I'll interpret "enforced" as meaning that workers who refused the injections would lose their job. I don't think there's any implication of physical force being used against workers (although the article doesn't go into detail there).