Here is an entertaining article on smoke pellets from CTT.
I think any particulate that can be inhaled might cause cancer. (not that I have any training on the subject)
Things that were thought to be safe last year might be declared a cause tomorrow.
Liquid smoke puts oil vapor in the air. Is that safer?
From Dr. Lechner's article:
Is this toy train pseudo-smoke harmful to your health?
Well, a jar of pure meta-terphenyl is labeled an "irritant," meaning that chronic exposure can irritate the eyes, skin, and mucous membranes. Some chemical substances in smoke fluid can also be moderate eye irritants and slight irritants to mucous membranes.
Common sense suggests that hobbyists provide themselves with at least some ventilation in their train rooms and that they find some fresh air if they experience headaches, sore throats, eye irritation, or itching skin after standing in a cloud of toy train "smoke."
