A question: How come all the bottles of mustard oil in Indian groceries have labels that say, "For Massage Use Only. Do Not Take Internally." Is this a warning I should heed? Is there something toxic about mustard oil? If so, why do none of the Indian cookbooks--which sent me to the market in search of mustard oil in the first place--warn me about it? Is it a purity issue: are there certain mustard oils not refined enough--or refined too much--for cooking? If so, are there pure mustard oils designed spcifically for cooking? I've seen some bottles labeled "mustard-flavored oil" that proclaim they're suitable for cooking, but they seem to be mostly made of soybean oil. Is this what I want? What's going on here? Should I take up massage and forget about teaching myself to cook Bengali food?