Indeed, we seem to have ample evidence that Tylenol seems to be strongly associated with autism[1] and weakly with ADHD[2], yet its use is not only widespread but unquestioned. The problem, of course, is that it's complicated; correlation isn't necessarily causation. So how to respond? Should all high school students be taught how to think critically of bioscience results? It's not easy to distill down to distinct usable facts. Suggesting at all that it is safe for teens to vape THC is a very dangerous proposition. I think you'd have to at least prove that it is safer than lead in gasoline, and that is not easy.
[1] https://www.ncbi.nlm.nih.gov/pubmed/18445737 [2] https://pediatrics.aappublications.org/content/early/2017/10...