Let me start with a confession. Like many of you, I believed a few things about electronic cigarettes—especially nicotine-free vapes. First, I thought the main risk came from nicotine and that, without it, vaping liquids were relatively harmless. Second, I figured that e-cigarette industry tweaks—like using more vegetable glycerin (VG) and less propylene glycol (PG)—must make these products safer. Third, I assumed that the absence of visible, immediate effects on users meant we were in the clear.
Here’s the shock: every single one of those beliefs has just been debunked. Let’s challenge and then unravel these mainstream ideas, using the latest research from mouse models and the cold, hard lens of developmental biology.
First, the claim that “no nicotine means no risk” is a dangerous oversimplification. Second, the popular shift toward VG-heavy vape liquid blends might not be the public health win we imagined. Third, just because you can’t see harm right away doesn’t mean nothing’s happening—especially to the most vulnerable, developing life.
Let’s dig into what the science actually shows, and why this matters for anyone who cares about the next generation.
The Unseen Risk: What Happens When Fetal Development Meets Vape Liquids?
If you’ve ever scrolled through FreeAstroScience, you know I care deeply about making science accessible—especially when the stakes are high. So, what exactly did this new research uncover?
A team led by James Cray at Ohio State University set out to untangle whether vape liquids, even without nicotine, could affect fetal development. They focused on the two core humectants—the “carriers” that give vape clouds their signature feel and look: propylene glycol (PG) and vegetable glycerin (VG). The idea was simple: expose pregnant mice to aerosols of these chemicals in ratios that mimic what’s actually in commercial e-cigarette liquids, but without any nicotine or flavourings, and see what happens to their pups’ skulls.
Here’s what they found: exposure to a so-called “safer” blend of 30% PG and 70% VG produced statistically significant changes in the facial structure and skull size of newborn mice. Pups exposed in utero to this blend were consistently born with narrower, shorter heads and faces—across both male and female litters. Their body weights were also lower than pups whose mothers breathed only filtered air or were exposed to a 50/50 PG/VG blend. None of these changes required nicotine to be present. In fact, the more “traditional” 50/50 blend didn’t have the same measurable impact .
Why does this matter? Because around 3% of babies are born each year with a birth defect, and craniofacial anomalies—like cleft lip or palate—are among the most common. Even small alterations in the shape and growth of the skull during development can have lifelong consequences, requiring surgery, therapy, and ongoing care. These are not minor cosmetic issues; they are deeply impactful disorders that affect breathing, feeding, speech, and self-image .
The Devil Is in the Formulation: Why “Safer” Might Be Just a Marketing Myth
Let’s pause for a moment and ask: how did we get here? Why did scientists expect the VG-centric blend (30/70 PG/VG) to be safer?
The e-cigarette industry has long argued that reducing PG (which is linked to increased nicotine uptake and the formation of certain toxic byproducts) would make vape liquids less harmful. So, as a response to public health pressure, many companies reformulated their products to favour VG—hoping to create a “cleaner” option for consumers .
But the mouse study flipped this expectation on its head. The 30/70 blend, marketed as a better alternative, actually produced more pronounced developmental changes than the 50/50 blend. The effect was consistent across multiple litters and both sexes. This is a classic case of unintended consequences: what’s marketed as safer, based purely on chemical reasoning and adult outcomes, turns out to have hidden risks for the developing fetus .
This finding is a wake-up call. It tells us that chemical carriers—not just nicotine or flavourings—can act as environmental exposures that alter development. The notion that “nicotine-free” means “risk-free” is, quite frankly, wishful thinking.
Mechanisms and Mysteries: What’s Happening Inside the Developing Skull?
So, what’s the science behind these changes? Are these effects relevant to humans, or just a weird quirk of mouse biology?
The researchers used 3D scans to measure the skulls and faces of mouse pups at two weeks old. The changes—reductions in cranial width and height, facial width, length, and nasal dimensions—were all statistically significant in the VG-heavy group. While the reductions were in the range of 2–5%, that’s enough to matter in craniofacial development .
There’s some preliminary evidence from other studies that exposure to PG/VG (even without nicotine) can disrupt genetic pathways crucial for bone and facial growth. In particular, the Wnt signalling pathway—essential for neural crest cell migration and facial formation—may be altered by these chemicals or their combustion byproducts. Disruptions in this pathway have been linked to real-world craniofacial disorders .
Now, before you panic—mice aren’t humans, and translating these results directly to people is tricky. But animal models have been essential for uncovering how teratogens (substances that cause birth defects) operate. Time and again, what’s found in the mouse lab ends up giving us critical early warnings for human health.
Regulatory Gaps and Real-World Implications: Who’s Protecting the Vulnerable?
Here’s the uncomfortable truth: electronic nicotine delivery systems (ENDS) are only lightly regulated in most countries, and companies have been aggressive in fighting back against tighter rules. The U.S. Food and Drug Administration only began regulating these devices in 2016, and it’s an ongoing legal tug-of-war .
Meanwhile, the products are wildly popular among young adults and teens—precisely the population most likely to become pregnant, sometimes before they even realise it. If fetal craniofacial development is affected by exposures early in pregnancy, as it is in mice, there’s a window where harm can be done before anyone knows to stop .
The upshot: “nicotine-free” does not mean “harmless,” especially during pregnancy. The chemicals used as carriers in vape liquids may have subtle, long-term effects on fetal growth and craniofacial development. Regulatory authorities, doctors, and users need to be aware that the absence of nicotine is not a free pass.
What Should We Do Next? Unanswered Questions and the Path Forward
Here’s my honest take, as Gerd Dani—President of FreeAstroScience, and someone who believes science should serve the public, not industry spin.
We need more research, urgently, into the health effects of e-cigarette carriers, not just nicotine or flavourings. We need better regulation, recognising that “safer” blends may have their own unexpected risks. And we need public health messaging that’s honest about what we don’t know—because science is a process, not a set of marketing slogans.
If you’re pregnant, planning to become pregnant, or know someone who is, the science right now says: avoid vaping, even nicotine-free products. The risk may be small, but it’s real, and it’s not worth gambling with the foundations of your child’s development.
Are there still open questions? Of course. Will future studies find the same effects in humans? We don’t know for sure. But when it comes to fetal development, isn’t it better to err on the side of caution?
So, next time you see a “nicotine-free” vape marketed as a safe alternative, remember: science is still catching up, and sometimes what you can’t see can hurt you—or, more heartbreakingly, your child.
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