Children absorb less secondhand nicotine through vapor vs. smoke

Key takeaways:

• Most parents who smoke now avoid it indoors around their children.
• Nicotine absorption was around 83% lower in children exposed to secondhand vapor vs. smoke.

Children absorb significantly less nicotine when they are exposed to secondhand vapor from an e-cigarette compared with secondhand smoke, according to a study published in JAMA Network Open.

Tobacco exposure has been linked to elevated blood pressure in children, and exposure to secondhand smoke has been linked to increased blood pressure in children and elevated odds of heart failure in adults, among other damaging health effects.

According to one of the authors of the new study, there has been “remarkable progress in reducing children’s exposure to secondhand smoke since the turn of the millennia.” As evidence, Harry Tattan-Birch, PhD, a research fellow in the department of behavioral science and health at University College London, cited a study published in The Lancet Regional Health – Europe that found the majority of parents who smoke now avoid it indoors around their children.

“In a previous study, we noticed that adults have a strong preference for vaping over smoking indoors: While only half of smokers smoke inside, nine in 10 vapers vape inside,” Tattan-Birch told Healio. “It is important to examine the extent to which this exposes children to harmful substances.”

Tattan-Birch and colleagues studied 2017 to 2020 data from the annual National Health and Nutrition Examination Survey, conducted in the United States. They specifically looked at blood tests in children that measured levels of cotinine, “a chemical that nicotine breaks down into in the body, which tells us how much nicotine they have absorbed over the past few days,” Tattan-Birch said.

“Our aim was to compare nicotine absorption in children with indoor exposure only to secondhand vapor, only to secondhand smoke or to nothing,” Tattan-Birch said.

Among 1,777 children aged 3 to 11 years, 270 were exposed to only smoke, 43 were exposed to only vapor, and 1,464 controls were exposed to neither.

The researchers found that nicotine absorption was 83.6% lower (95% CI, 71.5%-90.5%) among children exposed to only secondhand vapor (0.081 µg/L; 95% CI, 0.048-0.137) compared with children who were exposed to only secondhand smoke (0.494 µg/L; 95% CI, 0.386-0.633).

However, secondhand absorption was even lower among children with no reported secondhand exposure (0.016 µg/L; 95% CI, 0.013-0.021) — 96.7% (95% CI, 95.6%-97.6%) lower than the secondhand smoking group.

The findings revealed that “children absorb much less nicotine from indoor exposure to secondhand e-cigarette vapor compared to secondhand tobacco smoke,” Tattan-Birch said.

“These were the sort of reductions in exposure we would expect from studies in tightly controlled laboratory settings comparing vapes to cigarettes, but it provides confidence that the findings will be replicated in the real world,” Tattan-Birch said.

Because the data are from a period before the “rapid growth in disposable vape use among young people in the U.S. and U.K.,” Tattan-Birch said it would be interesting to replicate the study in the current vaping market.

“It is wise to avoid vaping indoors around children, as they will absorb some nicotine from this exposure,” Tattan-Birch said. “However, it is important to emphasize that smoking indoors is much worse. It exposes children to higher levels of nicotine and far higher levels of other harmful chemicals.”

He said vaping indoors is “preferable” to smoking indoors but still best avoided.

“Importantly, exposure to other noxious substances will likely be much lower still, given that e-cigarettes deliver similar amounts of nicotine to cigarettes but only a fraction of the toxicants and carcinogens,” Tattan-Birch said. “But both products raise nicotine absorption relative to no exposure, so it is best for adults to avoid vaping indoors around their children.”

References:

Tattan-Birch H, et al. JAMA Netw Open. 2024;doi:10.1001/jamanetworkopen.2024.21246.

Tattan-Birch H, et al. Lancet Reg Health Eur. 2022;doi:10.1016/j.lanepe.2022.100315.