What's In "Essiac"?

My understanding is that this crap (it is some kind of herbal concoction) was marketed for years as an anti-cancer drug. Now I see it hawked on the pages of the “Old farmer’s Alamanc”. Since they cannot claim it to be effective (as an anti-cancer drug0, on what basis can they sell this crap?
Anyway, the stuff is made in Canada-why does the Canadian government allow this stuff to be sold? :confused:

Burdock Root, Slippery Elm Inner Bark, Sheep Sorrel and Indian Rhubarb Root