Autoxidation of Glycols Used in Inhalable Daily Products: Implications to the Use of Artificial Fogs and E-cigarettes

XINYANG GUO, Ya-Chun Chan, Tania Gautam, Ran Zhao, University of Alberta

     Abstract Number: 67
     Working Group: Indoor Aerosols

Abstract
With the expansion of the entertainment and vaping industries, many workers and consumers have experienced various adverse health effects from poor indoor air quality (IAQ). Inhalable glycols are common chemicals used in these industries. Although the ingestion of glycols is considered safe, inhalation risks associated with glycols are not well understood. Our previous work has highlighted a rapid accumulation of formaldehyde and glycolaldehyde in artificial fog on the stage, thus proposing the occurrence of glycol autoxidation. However, chemical processes causing carbonyl formation and their implications for consumer and occupational health remained poorly understood.

This work is aimed to monitor the autoxidation process of glycols during storage. More specifically, a systematic study on the intermediate and the product autoxidation will be performed. The effect of storage conditions and the composition of the solution will be evaluated, for instance, air exposure and water mixing ratio. Lastly, the effectiveness of antioxidants will also be explored.

Our previous results recognized that triethylene glycol (TEG) is the major source of toxic carbonyls in fog juice. Hence TEG is predominantly investigated for the fundamentals of autoxidation. Other common glycols, such as glycerol, propylene glycol, diethylene glycol, and e-juice are also involved. Carbonyls were quantified using liquid chromatography-mass spectrometry (LC-MS), and peroxides from autoxidation were monitored via iodometry and UV-Vis spectrometry. By monitoring the aging of glycols, a formation of formaldehyde and glycolaldehyde was observed in all glycols. We confirmed that air exposure is the driving force of autoxidation. The water mixing ratio of the glycol also matters as a water ratio of up to 50% is accelerating the reaction. Additionally, vitamin C has effectively minimized autoxidation despite the storage condition. Our results provided a detailed investigation of glycol autoxidation, suggesting that improper storage of inhalable glycols is significant for indoor carbonyl exposure.