As this is a highly refined and puried single chemical component, you are unlikely to have biological or physical hazards associated with it. I believe that USDA FSIS does have regulatory limitations on its use, so a quick electronic search of 9 CFR ought to locate that. The MSDS will also have information concerning risks associated with various intake levels. There are probably some mongraphs on its risk, given that it has been a food component of great discussion here in the US in the past. Might just try an internet search for 'sodium benzoate & risk' (or hazards).