There are some but they are pretty much easy to manage. One that many people wonder about is the gas. It is not uncommon for people to confuse CO2 with CO which is carbon monoxide. CO is very dangerous but totally different than CO2. CO2 is only dangerous to breathe if you stay in a place where it replaces the oxygen we need. If you go into a closet and close the door and turn on the CO2, you might get there. But in most cases it will go down to the floor and run out like water would. But the real hazard is if you let the bottle tip over and it hits something hard enough to knock the top off. Then the compressed gas is like the torpedoes used in WWII. It can knock holes in walls. So strap it to something so it doesn't tip over and hurt itself --- or you?
The gas coming out will be like all gases which are decompressing. It will be very cold and if you stand still long enough, it can burn your flesh. Most of us are quicker than that. It may scare the pants off the first time it happens but most of us are quicker than the normal toad stool which gets us clear! Don't leave it in a hot car. It can get hot enough to vent off some gas. But if you can stand the heat, the tank probably will do fine. I put it in the trunk and strap it down. Never had one vent but it might someday?
They store the tanks outside on concrete docks here in Austin so I figure the heat issue is not a biggie! I'm thinking if I'm left on the dock in the summertime around here, I'll vent before the tank does.
Keep in mind that the same CO2 tanks are used to drive the soda machine at McDonald's so if those folks can do it safe, I'm okay.