DISCLAIMER: I am not an industrial hygenist or toxicologist. I've sent an email to US OSHA to ask what they think of using methanol or denatured alcohol in camping stoves.
I've done a bit more research on inhalation toxicity for alcohol fuels. My tentative conclusion is that with decent ventilation inhalation of methanol is probably not a problem when used outside (not in a tent). In a tent, it's probably not a problem unless you spill it. If you spill some inside a tent, stay out of the tent until it's thoroughly aired out (20 minutes to an hour?) Of course, carbon monoxide can be a serious problem if you cook in a tent.
OSHA = US Federal Occupational Safety and Health Agency
PEL = Permissible Exposure Limits based on an 8 hour average.
Methanol OSHA PEL†: TWA 200 ppm (260 mg/m3)
Ethanol OSHA PEL: TWA 1000 ppm (1900 mg/m3)
Carbon Monoxide:OSHA PEL†: TWA 50 ppm (55 mg/m3)
So methanol inhalation is significantly less toxic than CO by about a factor of 5, and ethanol is less toxic than methanol by a factor of 5.
Spilling 100 g of methanol in a tight tent will certainly exceed this PEL level of 260 mg/m^3. If we assume it all evaporates immediately in a tent of 3 m^3 volume:
Initial concentration will be:
33,000 mg/m^3. Assume the tent with door/windows open has 6 air changes per hour, and not really solving the differential equation, roughly:
after 10 minutes -- 16,000 mg/m^3
after 20 minutes -- 8000 mg/m^3
after 30 minutes -- 4000 mg/m^3
after 40 minutes -- 2000 mg/m^3
after 50 minutes -- 1000 mg/m^3
after 60 minutes -- 500 mg/m^3
after 70 minutes -- 250 mg/m^3
If you can mop up most of it before it evaporates, you can cut this time down considerably.