PP1320 - Effects of Electronic Nicotine Delivery Systems on Hearing Sensitivity with a Focus on the Ultra-High Frequencies (9–16K Hz)

The study aims to determine if vaping using e-juice containing propylene glycol has a negative effect on hearing thresholds, primarily focusing on the ultra-high frequencies 9 kHz – 16K Hz.

 “Ejuice,” the liquid component of the ENDS unit, is the substance of concern as it applies to the auditory system. The typical components that comprise “ejuice” are nicotine, propylene glycol, glycerin, and flavoring. Propylene glycol has been associated with ototoxic properties in animals. While it is also used as a food preservative and deemed safe in controlled quantities, little is known about its inhaling effects.

 

Summary:

Electronic Nicotine Delivery Systems (ENDS) use continues to be alarming in the United States and Europe. The CDC reported that 2.55 million U.S. middle and high school students said they currently (past 30-day) used e-cigarettes in 2022, which includes 14.1% of high school students and 3.3% of middle school students. In 2021, 4.5% of adults in the USA report vaping.

The study aims to determine the effects of ENDS use on hearing sensitivity, primarily in the ultra-high frequencies. The study focuses on ultra-high frequencies, as this is where one would expect to see the effects occurring in the form of a decrease in hearing sensitivity based on the potential ototoxic-related properties of propylene glycol. It is well documented that the effects of ototoxic substances evidence the adverse effects in the ultra-high frequencies first, as the outer hair cells of the basal end of the cochlea are damaged. ⁱⁱⁱ   If we can identify a decrease in the ultra-high frequencies, early downward spreading may be slower or prevented. While not all “ejuice” contain nicotine, many of the 7,000+ flavors do. This is alarming as nicotine is addictive. Equally troubling is that 95% of the “ejuice” has a base of propylene glycol and glycerin. Once the liquid takes on the aerosol characteristic, heavy metals are released in the vapor and consumed by the body.

Subjects recruited for the study will be between the ages of 18-40. An email questionnaire will be sent to the interested individual to determine candidacy and group assignment (vapers and non-vapers). The questionnaire will include both inclusion and exclusion criteria to ensure they report their status as current vapors meeting the inclusion criteria. Those individuals meeting the inclusion requirements will be contacted via email to set up a screening appointment. Individuals meeting the inclusion criteria and audiometric screening parameters will be entered into the study as subjects.

Subjects will be tested utilizing the GSI audiometer to establish pure tone air and bone conduction thresholds from 250-16 KHz. The GSI TympStar will be used to record the integrity of the tympanic membrane and assess the middle ear status. The Intereacoustics evoked potential unit will be used to obtain Distortion Product Otoacoustic Emission (DPOAE) on each ear.

Data is being collected and anticipated to be completed in December 2023.