Recently, a study piblished on ACTA TABACARIA SINICA has finally draw the conclusion that the testing on Wistar rats exposed to atomized glycerol in 90 days shows no inhalation toxicity.
The ACTA is the core journal of China Tobacco Society, a national non-profit academic society founded in 1985 and made by workers in tobacco science technology and organizations of the tobacco industry.
Glycerol is a colorless, transparent, odorless and sweet viscous liquid. It has been widely used in tobacco, cosmetics, coatings, textile, food and pharmaceutical industries due to its moisturizing, plasticizing, flavoring, thickening, anti-corrosion and other effects. In traditional tobacco products, 1%~5% glycerol is usually used as a moisturizer and a surfactant for tobacco flavors. In recent years, with the rise of new tobacco products, glycerol has become an important part of tobacco raw materials, especially in vape, and as an atomizer of E-liquid, its concentration can reach more than 90%. Therefore, the research on the toxicity of glycerol has become particularly important. As a food additive, glycerol's toxicity has been reported. However, there are few studies on glycerol inhalation toxicity. So far, only Greenspan and Renne's research team have reported on glycerol toxicity.
Although Greenspan and Renne have studied the inhalation toxicity of glycerol, it’s is relatively low for the concentration of glycerol in their research (≤ 4 mg / L), which is still far from the minimum concentration of 4.45 mg / L in vape e-liquid in the market. However, there are few studies on the high concentration and high dose of glycerol.
Below is the brief abstract of the research：
[Objective] This work aims to understand the inhalation toxicity of glycerin as electronic cigarette atomizing agent.
[Methods] In this work, 120 Wistar rats were selected as research objected subjected to 90 days of inhalation toxicity test, with 28 days of recovery. The rats were randomly divided into a negative control group, a low-dose group (10 mg/kg), a medium-dose group (100 mg/kg) and a high-dose group (750 mg/kg) according to their body weight. There were 30 animals in each group, half male and half female. During the experiment, the changes in animal body weight and food consumption were detected. After the exposing period and recovery period, hematology, blood biochemistry, urine and other endpoints were detected, Broncho alveolar lavage fluid was analyzed, and histopathological evaluation of animal organs was conducted.
[Results] Compared with the negative control group, the male rats in the medium dose group exhibited significantly decreased food consumption at week 3 (P<0.05), while the female rats in the high dose group exhibited significantly decreased food consumption at week 6 and week 11 (P<0.05). The MCH (mean erythrocyte hemoglobin) level significantly increased in the male rats of medium dose group during recovery (P<0.05) and the level of PLT (platelet count) was significantly decreased (P<0.05). There was no significant difference in blood biochemistry among the treatment groups (P>0.05).
The urine specific gravity in the low dose group increased during recovery period (P<0.05). The weight of liver and kidney in female rats of the high-dose group were lower than that of the negative control group during exposing period (P<0.01). During the recovery period, lung weight in male rats of the medium dose group was lower than that of the negative control group (P<0.01). There was no significant difference in broncho alveolar lavage fluid: among the treatment groups (P>0.05). No obvious lesions were found in the organs of the negative control group and the high-dose group according to histopathological evaluation. The changes of the above indicators showed no dose-effect relationship.
[Conclusion] Therefore, no significant toxic effect was produced on rats after 90 days of inhalation of glycerin at the exposure dose of 750 mg/kg.