The rise of nicotine vaping as an alternative to traditional smoking has sparked never-ending complaints about its safety, with propylene glycol (PG), a common ingredient in e-liquids, often targeted as a health concern. Critics deceptively claim PG is harmful when inhaled, citing its use in industrial applications or conflating it with unrelated products like antifreeze.
However, scientific evidence and regulatory assessments overwhelmingly demonstrate that PG in vaping is safe for inhalation at the levels used, and these claims are largely rooted in misinformation.
Propylene glycol is a colorless, odorless liquid widely used in food, pharmaceuticals, and cosmetics. In vaping, it serves as a base for e-liquids, helping to dissolve nicotine and flavorings while producing vapor users exhale. Its safety profile is well-established: the U.S. Food and Drug Administration (FDA) classifies PG as “Generally Recognized as Safe” (GRAS) for ingestion and topical use. While inhalation is a different exposure route, studies specific to vaping show no cause for alarm.
The Antifreeze Trope
One common misconception is that PG’s use in non-vaping contexts, such as antifreeze, implies toxicity. This is misleading. PG is used in non-toxic antifreeze formulations precisely because it is safer than alternatives like ethylene glycol, which is highly toxic. The two compounds are chemically distinct, and PG’s safety in vaping hinges on its specific properties and exposure levels.
Studies Show Low Risk
Numerous studies support PG’s safety in vaping. A 2017 study published in Scientific Reports examined the inhalation effects of PG-based aerosols in animal models and found no significant toxicity or inflammation at vaping-relevant doses. Human studies, such as those reviewed in a 2018 Public Health England report, confirm that vaping PG produces minimal respiratory irritation and no long-term harm under normal use. Occupational exposure studies, where workers inhale much higher doses of PG in industrial settings, further show no adverse health effects.
Carefully evading this evidence, anti-vaping activists will sometimes pivot and claim that PG breaks down into harmful compounds when heated. While high temperatures can produce trace amounts of formaldehyde or acetaldehyde, modern vaping devices operate at controlled temperatures (typically 200-250°C), minimizing such risks. Multiple studies published over the last decade have found that harmful byproducts from PG are negligible under standard vaping conditions, unlike the combustion in cigarettes, which generates thousands of toxic chemicals.
Critics also point to anecdotal reports of PG causing allergic reactions or throat irritation. While rare individuals may be sensitive to PG, these effects are mild and not indicative of systemic harm.This is a far cry from the severe health risks of smoking, which causes over 480,000 deaths annually in the U.S. alone. Critically, most people are routinely exposed to PG through the myriad products they use every day.
Regulatory Agencies Agree
Regulatory bodies, including the FDA, have reviewed PG in vaping and found no evidence of significant risk. Public Health England’s 2015 report famously stated that vaping is at least 95% safer than smoking, a conclusion partly based on PG’s benign profile. Misinformation about PG often stems from fearmongering, conflating vaping with smoking’s dangers and ignoring the stark differences in chemistry and exposure.
The persistent hyperventilating about PG in nicotine vaping products is designed to do one thing: distract the public from the realization that vaping is significantly safer than smoking. If that truth gets out and more smokers switch to vaping, tobacco control activists will lose their reason for being—and their jobs. That, I suggest, is the real reason this and so many other baseless myths about vaping continue to circulate.
