Ever since I was a child, salted butter was a taboo in our family. Reason being, my ancient Chinese grandma (full of hearty wisdom, I might add) once told us that you cannot put salted butter on silver, lest it become carcinogenic. Apparently, my parents value our silver butter plate more than my love of salted butter, and thus I have been living out my life, deprived of the butter I love, for a long, dark, 13 years.
Grandmas, God bless them, tend to be a fertile source of ULs. I can’t give you any specifics on the butterfat/NaCl/Ag cancer connection but there are lots of other fatty, salty foods that are served on silver that are not specifically carcinogenic.
Sometimes I wish my own mother was more vigilant about hidden kitchen hazards. It’s taken me years to make her stop thawing meat in the sink.
Rejoice! For I have come to release you from your self-imposed bonds of silver-plated-(salted)-butterlessness!
First off, may I say that butter without salt in it is almost useless. Bleh.
Now on to the issue at hand: Using a silver dish for your (salted) butter is a bad idea pretty much any time - but NOT for the reasons stated.
See, salt digs pits in silver, eats it away somehow, so salted butter will eventually damage the silver, but I’m fairly certain it won’t make your butter carcenogenic. At least I’ve never heard the medical world back this idea. (Of course, the butter probably won’t taste quite right with corroded silver bits floating around in it, but hey…) Methinks gramma was just trying to protect her purty butter dish.
Besides, just about everything can lead to cancer, so put the dang butter on silver if it pleases you. Just don’t expect the silver to like it.
StoryTyler
I am too in shape! :::muttering::: Round is a shape.
Forgot to mention - butter dishes come in all sorts of “safe” materials…! Let’s don’t get to hung up on SILVER butter dishes, shall we? 
I personally have a porous ceramic butter dish with cover - you can leave this out on the counter or table at all times (except in the hottest climates). Simply soak the dish and cover in cold water for a few minutes before adding the stick of butter. The ceramic keeps the butter cool enough so it doesn’t melt, but not so hard you need a hammer and chisel to cut it.
StoryTyler
I am too in shape! :::muttering::: Round is a shape.
This is from the Los Alamos National Laboratory’s CST Division’s Periodic Table of the Elements
Handling
While silver itself is not considered to be toxic, most of its salts are poisonous. Exposure to silver (metal and soluble compounds, as Ag) in air should not exceed 0.01 mg/m3, (8-hour time-weighted average - 40 hour week). Silver compounds can be absorbed in the circulatory system and reduced silver deposited in the various tissues of the body. A condition, known as argyria, results with a grayish pigmentation of the skin and mucous membranes. Silver has germicidal effects and kills many lower organisms effectively without harm to higher animals.
So isn’t there a chance that the NaCl in the butter and the silver could perform a little exchange and make silver chloride? Maybe not carcinogenic, but poisonous.
The Merck doesn’t give LD50s for silver chloride, nor does it say Poisonous! the way it does for silver cyanide (pretty obvious, that one) or silver nitrate.
It also says (under the entry for silver) that “Does not cause serious toxic manifestations … Many silver salts are irritating to skin, mucous membranes.”
I can personally attest to the fact that silver chloride is not particularly toxic, as I work with it on a fairly regular basis. It is highly insoluble in most everything, and therefore has limited ability to interact with you. Its most common reaction is to reduce to silver metal either under the action of a reducing agent or light.
Also, given the common use of silver iodide, a very closely related compound, as a therapeutic agent and for seeding clouds to make it rain, I would guess that the toxicity is pretty low.
It’s hard to know what warnings to take seriously as my bottle of sand keeps warning me that sand is a suspected carcinogen and may cause suffocation.
TheDude
I guess that’s all well and good, but none of you seem SURE that the said combination does not produce a carcinogen. And Tyler, I don’t think you understand: my mom is so obsessed with the silver butter platter that the only other way she would allow me to obtain my butter would be straight from the… what do you call those things butter comes in? I wonder if they sell salted butter in those little mini-packets you find in restaraunts. I suppose that would be wasteful, though. All that plastic just because little old me wants salted butter on his toast.
If silver chloride were a known or suspected carcinogen, there would be warning labels out the wazoo on it. Clearly it was not, at the time my copy of the Merck was printed, because they are quite careful to label such things.
Does that mean it can’t possibly cause cancer? No, it doesn’t. If you’re looking for guarantees, you’re looking in the wrong place.