Earlier quoted context omitted.
What adverse health implications from vaping are there?
Still being studied, but the idea that it’s safe seems to be a very odd default. https://www.cdc.gov/tobacco/e-cigarettes/health-effects.html Why would your default assumption be that putting foreign (and poorly regulated) substances into your lungs is more likely than not safe? This is especially true since it’s a drug that doesn’t even have much claim to fame for positive recreational or medicinal benefits.
Also gov regulation is not the only form of regulation. Fear of getting sued by your customers into bankruptcy is an effective regulation on putting harmful substances into your vape.