Conditions Leading to Ketene Formation in Vaping Devices and Implications for Public Health

Area of Science:

• Environmental Chemistry
• Toxicology
• Analytical Chemistry

Background:

• The 2019 e-cigarette or vaping use-associated lung injury (EVALI) outbreak caused thousands of hospitalizations and deaths.
• Vitamin E acetate (VEA), an additive in illicit tetrahydrocannabinol (THC) products, is strongly implicated in EVALI.
• A suspected mechanism involves ketene, a toxic gas, produced from VEA thermal decomposition during vaping.

Purpose of the Study:

• To develop and apply a novel method for detecting ketene production from VEA vaping under realistic conditions.
• To investigate the relationship between vaping parameters (temperature, device power) and ketene formation.

Main Methods:

• A novel approach was used to evaluate ketene production from VEA vaping in real-world devices at controlled temperatures (200-500 °C).
• Ketene in generated aerosols was captured using two chemical agents.
• Analysis was performed using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography with tandem mass spectrometry (LC-MS/MS), with LC-MS/MS showing higher suitability for large sample batches.

Main Results:

• The study confirmed ketene formation when VEA was vaped.
• Ketene production increased with repeated puffs and correlated with vaping temperatures.
• Device battery power significantly influenced heating temperature and subsequent ketene formation. Duroquinone was also identified as a VEA thermal degradation product.

Conclusions:

• Vaping vitamin E acetate (VEA) generates toxic ketene gas, providing a plausible mechanism for EVALI.
• Ketene formation is dependent on vaping temperature and device power.
• The acetate group in VEA is crucial for ketene generation, as ketene was not detected when vaping vitamin E alone.