All raw food in the US uses USDA human grade meats..... So..... :dk: ????Hey there, I'll be interested in that additive too...!
The only one I can think of which definately applies in Australia - although I'm sure it's used world wide - are the sulphite family of preservatives. Thankfully human grade food has to have this labelled. Pet grade food doesn't, and its use is rampant. I've also heard it is obligatory in the pet food Kangaroo - the carcasses get separated into two piles (human/pet) and then the pet ones are treated - so the 'manufacturer' can actually not even be aware its in the 'food' as they didn't put it there. As far as I know, this isn't something that directly/primarily affects the brain though, (unless we call the brain the central nervous system, which obviously it forms a major part)? It will kill your cat over time as it destroys thiamine, and will destroy it in other 'clean' food sources if the 'contaminated' source has already been consumed - ie, within the animal after ingestion. Thiamine deficiency affects the central nervous system and cats (and dogs) lose ability to lift their heads and walk, and will cause death.
I'll be checking back for the name of that additive you know about