I hope you explore Titanium more thoroughly. I have spent my life developing titanium alloys for high temperature application in gas turbine engines and have over the years devoured virtually every word in the scientific literature relating to titanium and titanium dioxide.
I am unaware of a single case where titanium dioxide was associated with harm to a human being both in the processing industry for the raw metal or in facilities that produce titanium dioxide for consumer products such as paint, toothpaste etc. It's unfortunate that people who exposed themselves to true harm
through long term smoking of
tobacco do not have valid information or do not take the opportunity to find the information that is available about the relative dangers of materials used in smoking alternatives such as
vaping.
Duane