PG, PEG, and MCT are commonly used filler oils in vape cartridges as they are cost-effective cutting agents. When ingested, these compounds cause no known harm to humans. However, when vaporized, these oils pose potential health risks. When heated, PEG has been known to produce high levels of acetaldehyde and formaldehyde (cited by the National Institute of Health). Screening for these compounds in vape cartridges will ensure the safety of patients and consumers.