Found some:
"The virtual NONTOXICITY of glycerine as an ingredient in foods and pharmaceuticals has been established through generations of safe use and by supporting data":
(U.S. Food and Drug Administration, Glycerin; AJirrnation of GRAS Status as a Direct Human Food Ingredient, Federal Register, Vol. 48, No. 27, pp. 5759-60)
Also, apparently it comprises about 3% of cigarette and cigar tobacco.
http://www.aciscience.org/docs/glycerine_-_an_overview.pdf
"The virtual NONTOXICITY of glycerine as an ingredient in foods and pharmaceuticals has been established through generations of safe use and by supporting data":
(U.S. Food and Drug Administration, Glycerin; AJirrnation of GRAS Status as a Direct Human Food Ingredient, Federal Register, Vol. 48, No. 27, pp. 5759-60)
Also, apparently it comprises about 3% of cigarette and cigar tobacco.
http://www.aciscience.org/docs/glycerine_-_an_overview.pdf