So either they think there is a level of cannabis use that is zero risk, or they have a different definition of safe consumption that they could elaborate on.
I don't think the same can be said for cannabis use
Even if we concede the cancer risk, there are other risks that may be unarticulated.
(That said as someone who abstains from both alcohol and cannabis)
The same can already be said of cannabis.
"People who use marijuana have an increased risk of heart disease and heart attack, according to a large study led by researchers at Stanford Medicine.
The study also showed that the psychoactive component of the drug, known as THC, causes inflammation in endothelial cells that line the interior of blood vessels, as well as atherosclerosis in laboratory mice." [1]
Other studies have shown the risk of heart attack goes up in the first hour after smoking cannabis.
Prohibition doesn't work. And we need loads of more studies like this so folks can be well informed in their choices.
However regulations and taxes do work. Smoking cigarettes continues to become less and less popular thanks to information, higher taxes, and other regulations.
Considering how popular cannabis is, we should be funding more research so we can make informed choices, and at tax it at a level that recovers the actual cost to society.
[1] https://med.stanford.edu/news/all-news/2022/04/marijuana-hea...
The difference between toxicity and therapeutic use is what helps define the safety of the substance. There are some, like psilocybin mushrooms, that have a relatively monstrous gulf between therapeutic doses (in the mcg) and toxic doses (presumably in the kg). They are quite safe, though not zero risk. I believe alcohol is relatively unsafe by that measure, while cannabis is pretty darn safe. But that's not the same thing as saying "zero risk". I think the poster is just imprecise with their language when they mean to say "safe" and not "zero risk".
As far as cannabis being "pretty darn safe", a recent study shows it causes heart disease. And more than one study shows it increases the risk of heart attack for up to an hour.
What we really need is an end to prohibition, and continued funding for studies on the substances that are the most popular so folks can make the most informed choices.
To apply this to your example, cannabis was linked to heart disease in daily smokers. As one would expect, the study showed a dose dependent relationship with cannabis and risk.
Just like you can find “some” people who drink daily and become centenarians, you have to be careful about the way you characterize the risk. I believe the better data show more than 4 drinks a week does increase your health risk substantially.
In both cases, it seems like moderation is key, although I maintain cannabis is far safer when you compare the ratio of therapeutic to toxic dosage. But that’s acute risk, where the study you’re talking about is chronic risk.