As I stated in another thread, wax it with carnauba car wax. That will keep the moisture from tarnishing it about the same amount of time as your car.
Not sure about the toxic part but that stuff you put on your windows to keep the rain off might work too, I think it is a carnauba type product.
Now remember though if the tarnish is still there like when you use tarnx or brasso it is still going to show in a short amount of time.
Brasso/tarnx, all it is is bleach, it takes the color out but doesn't actual take the oils off the brass, that's why it is quick, but tarnish comes back rather fast.
After you polish real well, wax it with a carnauba car wax. This will keep the moisture from the air & oils from your hands off it for aprox a year.
A good choice is Wenol & Friltz. That is what I used on silver drinking goblets