I'm not sure I agree that advertising is the most sane course of action here - if you take tobacco as a reference then the intervention that causes the highest decrease in usage is tax (and higher price coincidentally usually leads to lower usage rates especially in younger people because they're more price sensitive). So if banning is too far to go, then a middle ground might be to have a very high tax on the product in order to 1) decrease usage and 2) put money into a fund in case all these users end up getting a new form of cancer in 20 years that we didn't see coming and that we (society/the state) have to collectively pay for