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March 26, 1970 SODIUM SILICATE AS AN ADDITIVE TO TOBACCO. Sodium silicate is an inexpensive, deliquescent, alkaline salt, w~th umny commercial uses, including the preservation of eggs and the fireproofing of fabric~ and paper. It was proposed as an additive to tobacco because the above mentioned properties should increase, the equilibrium moisture content of the tobacco, decrease its buz~Lng rate, and selectively alter the smoke composition, especially by reducing the delivery of HCN, and increasing the nicotine delivery. Initial trials discussed last year, in which sodium silicate solutions were injected by syringe into cigarettes, were successful in all these aspects. Studies have since been made of . cigarettes manufactured from cut flue-cured tobacco presprayed with silicate solutions. The additive did not increase the silica content of the smoke compared to that from the control cigarettes (each 0.7 ~g per cigarette). Subjectively, cigarettes containing 2.5Z silicate had a highly acceptable smoke with respect irritation, preference and quality of taste, and gave a slightly greater amount of taste than the control additive level, the smoke was not acceptable, although no unusual taste was detected. Thus, 2.5Z may be near the subjectively acceptable limit, but even at this level it offers many advantages in smoke composition. Sodium silicate did no1 affect ~he delivery of benzo(a)pyrene. Surprisingly, the 2.5Z level reduced the delivery of nicotine b~ 8.1Z. However, when yields of all other components were compare.~ to a common nicotine delivery, ~he 2.5Z level gave selective y~eld reductions of TPM (&.AZ), DPM (5.5~), HCN acrolein (11.9~), volatile acids (3.8Z), nitric oxide (I~.YZ) and carbon monoxide (2.5~). However~ it gave selective increases in deliveries of water (8.8~), phenols (I&.~Z), aliphatic aldehydes (ll.~Z) and C02 (17.5Z). The additive gave a small reduction in rate of burn of the cigarettes, and it increased the equilibrium moisture content and the degree of combustion of the tobacco, wi~h 2.5Z producing • decrease in ~he CO/C02 ratio of 16Z. Sodium silicate costs less than 12¢ per pound. In the tests the cut rag was sprayed with a solution whose total weight represented 20Z of tha~ of ~he tobacco. If the tobacco can be uniformly sprayed in the strip form with a solution whose concentration BAT Industries document for Province of British Columbia 9 November 2000 BAT INDUSTRIES 00290385

-2- is such ~hat the tobacco moisture conten~ is raised from 15Z ro not more than 19-20Z, then the use of silicate on tobacco at the 2.5Z level should not be complicated fro~ a manufacturing viewpoint and should not be costly. Sodium silicate had no noticeable effect on tobacco colour, It should have a preservative action on tobacco. Recommendations: i. Sodium sillcale should he submitted for approval to the / Additives Guidance Co--,Ittee at Millbank. 2. The effects of sodium silicate on the biologlcal activity / of smoke should be examined. 3. The effects of sodium silicate as an additive to PCL or in the treatment of stem should be studied. A comparative study should be made of other metal silicates as additives. ~AS/Ja 0 0 BAT Industries document for Province of British Columbia 9 November 2000 BAT INDUSTRIES 00290386