Nicotine absorption lower in children exposed to secondhand vapor compared to second hand smoke: JAMA

A new study published in the Journal of American Medical Association suggests that vaping inside instead of smoking may significantly lower the secondhand exposure to nicotine and other harmful compounds in children, despite both smoke and vapor increase absorption compared to no exposure. Children absorb far more nicotine from secondhand smoke than from secondhand vapor.

Over the last several decades, children's exposure to secondhand tobacco smoke has drastically dropped in many countries, notably in the US and England. Thus, there was a fall in parental cigarette smoking and an increasing number of the individuals who still smoke but not inside. There is another possible source of secondhand exposure to harmful compounds in indoor air due to the widespread use of nicotine e-cigarettes during the 2010s. Therefore, Harry Tattan-Birch and team wanted to evaluate the differences in nicotine absorption between children who are exposed to either secondhand tobacco smoke or secondhand vapor compared to those who are exposed to neither.

This study drew data from a nationally representative sample of US homes from the period of 2017 to 2020. The children who were of 3 to 11 years old with serum levels of cotinine below 15 μg/L were included in this study. The participants were questioned at home before visiting a mobile examination facility a few days later to give biological specimens and the final analysis was carried out on January 9, 2024. The exposure to secondhand smoke or vapor inside within the last seven days were assessed. The covariates included gender, age, household income, ethnicity, weight, and height. The main outcome was serum cotinine levels, which is an objective index of nicotine absorption.

They key findings of this study were:

The average (SD) age of the total 1777 children questioned was 7.4 (2.6) years, with 882 (49.6%) being female and 531 (29.9%) having household incomes below the poverty line.

The nicotine absorption measured by blood cotinine levels was highest among children exposed exclusively to secondhand smoke, followed by those who were subjected only to secondhand vapor, resulting in 83.6% decreased nicotine absorption.

Children with no documented secondhand exposure had a geometric mean cotinine level of 0.016 μg/L, which was 96.7% lower than those who were exposed to secondhand smoking. Overall, switching from smoking to vaping indoors can significantly reduce the children's secondhand exposure to nicotine and other toxic compounds, but not eliminate it completely.

Reference:

Tattan-Birch, H., Brown, J., Jackson, S. E., Jarvis, M. J., & Shahab, L. (2024). Secondhand Nicotine Absorption From E-Cigarette Vapor vs Tobacco Smoke in Children. In JAMA Network Open (Vol. 7, Issue 7, p. e2421246). American Medical Association (AMA). https://doi.org/10.1001/jamanetworkopen.2024.21246