Food safety hazards associated with gas powered fork lift trucks
Rubered
Well you have fumes from burning the fuel and the fuel itself. You'll need an MSDS for that as well. If there isn't good ventilation the fumes from burning the gas can change the flavor and smell of the product (that's more quality than safety)
Burning gas has a lot of things released.. I don't know them all but none of it is something you want in your product.
Generally speaking you don't usually want gas forklifts in a building, they should be battery powered. For many reasons, such as what Mr. I said above. But would also wonder about safety of personnel as well.