I don’t think the science is sketchy - I’ve linked 4 or 5 studies so far which seem to indicate that nicotine has cancer promoting effects and seem to be in mostly decent journals. (I’m not an oncologist ofc, if you’d like to make some arguments about the impact factors of those journals, that’s usually the last refuge of “the science clearly shows something I don’t like.”) Here’s another:

E-cigarette use has been reported to affect cell viability, induce DNA damage, and modulate an inflammatory response resulting in negative health consequences. Most studies focus on oral and lung disease associated with e-cigarette use. However, tissue damage can be found in the cardio-vascular system and even the bladder. While the levels of carcinogenic compounds found in e-cigarette aerosols are lower than those in conventional cigarette smoke, the toxicants generated by the heat of the vaping device may include probable human carcinogens. Furthermore, nicotine, although not a carcinogen, can be metabolized to nitrosamines. Nitrosamines are known carcinogens and have been shown to be present in the saliva of e-cig users, demonstrating the health risk of e-cigarette vaping. E-cig vape can induce DNA adducts, promoting oxidative stress and DNA damage and NF-kB-driven inflammation. Together, these processes increase the transcription of pro-inflammatory cytokines. This creates a microenvironment thought to play a key role in tumorigenesis, although it is too early to know the long-term effects of vaping. This review considers different aspects of e-cigarette-induced cellular changes, including the generation of reactive oxygen species, DNA damage, DNA repair, inflammation, and the possible tumorigenic effects.

And yes - we are surrounded by carcinogens. The harm of nicotine is that it facilitates those carcinogenic effects. If you’ll read that article, or the others I’ve linked - that’s what the problem is. Carcinogen + nicotine = increased risk of cancer.

if you want funding, find vapes to be harmful. If you want your career destroyed, tell the truth.

What is more financially incentivized here? Let’s “qui bono” our conspiracy theory.

Do you think that Juul or Phillip Morris or whatever wouldn’t fund studies that said vape is harmless? When we think, who has the money for funding, who makes money from the conception of vape as harmless…

Why exactly do scientists and the government have a “party line” against vapes? Do you not realize that the same arguments you are making now were made about cigarettes?

Edit: diving into that study more:

In some cases, cellular damage from e-cigs was found to be more extensive [my emphasis] than the damage imposed by traditional cigarettes [56]. Comparing the exposure of different bronchial epithelial cell isolates from COPD patients with vaporized JUUL and a reference standard cigarette showed augmented cell cytotoxicity, especially in response to flavored e-cig aerosols and LDH secretion as previously reported [57]. A 2019 study on the airway smooth muscle cells (ASMCs) of COPD patients showed increased secretion of IL8 following e-cigarette exposure, supporting other reports that e-cigarettes lead to increased neutrophilic inflammation in pulmonary tissues [55]. The findings in this study suggest the progression of COPD may be accelerated by e-cigarette use [55]. The pathogenesis of COPD is highly associated with increased inflammation, particularly from macrophages and neutrophils [55]. Of note, as previously mentioned, even the carrier liquid component propylene glycol can negatively affect the airways: Using bronchial epithelial cells and an in vivo sheep model, it was demonstrated that exposure to e-cig aerosol of 100% propylene glycol resulted in increased mucus concentration as relevant to lung disease and COPD [58], Figure 1. The exposure of human airway epithelial cells to e-cig aerosols can increase the secretion of inflammatory cytokines, such as IL6 and IL8. Furthermore, human lung fibroblasts show stress responses and morphological changes upon e-cig exposure, such as an increased secretion of IL8 or even cell death, especially after treatment with cinnamon-flavored e-liquid [59].