Propylene glycol
Propylene glycol (1,2-propanedol) is generally classified as an alcohol. It is a clear, colorless viscous liquid having a slight, characteristic, sweet taste. It is practically odorless and absorbs moisture when exposed to air. It may produce eczematous skin reactions of toxic nature and more rarely of allergic nature. It may irritate the eyes or skin and repeated contact may cause allergic dermatitis. Also, propylene glycol may reduce DNA synthesis in the tetraploid cells. Propylene glycol is a good solvent which has moisture regulating, antiseptic and preservative effects. And it gives a milder smoke. Propylene glycol’s primary function is as a processing agent. As a humectant it helps minimize the generation of dust and fines. Its secondary function is to act as a solubilizing agent for other tobacco additives, such as flavorants. Also it hinders tobacco mold formation. It is used as a humectant and as a filler additive. In 1984 the major tobacco companies used approximately .8% propylene glycol as a humectant in filler except the Liggett Group that used .4% propylene glycol. Back in 1958 Pall Mall contain 1.1 propylene glycol. Evidence had been collected by Philip Morris in the 1950s that propylene glycol when added to the filler gives a milder smoke. In 1958 Philip Morris’ judges found cigarettes having propylene glycol and TEG to be milder as compared with those using glycerine. At this time Philip Morris recommended to submit propylene glycol plasticized cigarettes for consumer tests since these cigarettes have been shown to deliver fewer tars and recommended tests to be done with propylene glycol as an emollient (soother anti-irritant) in the filter and in the filler at varying levels. In 1975 Philip Morris examined alternative methods of casing to reduce PG loses or eliminate PG and recommended to eliminate PG from ES casing. In 1978 Philip Morris conducted test designed to determine if the propylene glycol could be removed from the casing with no adverse effects on the quality of the expanded tobacco and thus realize a cost savings. They concluded to reduce propylene glycol 50 to 33% in the final product. Philip Morris conducted comparison test in 1986 for the replacement of a mix of the humectants PG and glycerine versus the humectant TEG in RCB and comparing the physical performance of RL and RCB with new humectants (propylene glycol and glycerine) replacing the old humectant TEG. They concluded the test cigarettes with a mix of PG (3%) and glycerin (4%) was rated subjectively equivalent to the control with 4.5% TEG. The industry examined in 1989 the specific levels of aldehydes and ketones that were determined in mainstream smoke with varying levels of propylene glycol and glycerine. According to RJR memo dated 1990 propylene glycol had been approved by Scientific Affairs for use in cigarette products. A 1991 RJR study concluded relocating propylene glycol from the casing for cutting to the top dressing did not affect overall perception. In 1994 Brown and Williamson conducted tests of low tar cigarettes pretreated with glycerol, propylene glycol or sorbitol and stated that propylene glycol treated gave a small decrease in nose irritation. CAS number: 57-55-6Chemical class: AlcoholsIndustry claims found in: sesame seed, mushroomIndustry claims used in: confection frostings, cheese, candy, baked goods, cereals, toppings, pickles, milk products, beverages and soupsPossible physical or functional effects: Anticaking agents and free-flow agents; Antioxidants; Dough strengtheners; Emulsifiers and emulsifier salts; Flavoring agents and adjuvants; Formulation aids; Humectants; Processing aids; Solvents and vehicles; Stabilizers and thickeners; Surface-active agents; TexturizersProperties: industry claims FEMA GRAS; industry claims FDA GRAS; used in cigarettes; used in smokeless tobaccoToxicology: LD50 (oral, rat) 25 ml/kg; eye/human skin irritant; sl. toxic by ingestion, IP,IV, subcutaneous routes; human systemic effects; experimental teratogenic, reproductive effects; mutagenic data; heated to decomp., emits acrid smoke and irritating fumes