Once you get the Sterno lit and the Sterno gets burning properly there's no health risk from the Sterno.
Sterno burns very clean and is safe to use indoors and I've used Sterno Indoors before during power outages to cook food and keep my hands warm.
I also use the Sterno when camping when I don't need my camper stove but just want to cook something really quickly.
I've also roasted marshmallows and hotdogs on Sterno before and it does a good job and is very safe.
Sterno is basically alcohol and gel mixed together and doesn't produce toxic fumes and Sterno is also not explosive like Propane is.
So Sterno is much safer than Propane is.