Thirdhand Smoke Researcher Shows Harms to Adolescent Health

A new study by thirdhand smoke researcher Dr. Ashley Merianos shows the impact of exposure to secondhand smoke on the health of adolescents. Secondhand smoke is the precursor to thirdhand smoke, the toxic residue that remains on surfaces and in the air after smoking stops. In his editorial, Dr. Harold J. Farber, editor of CHEST, reminds us that we need to do a better job at protecting our youth from toxic tobacco smoke.

September 2020

By: Harold J. Farber, MD, MSPH, FCCP

There has already been extensive research documenting the harms of involuntary tobacco smoke exposure on health. The report by Dr. Merianos and her colleagues in this issue of CHEST adds to this evidence base by documenting how many of our children are exposed, describing disparities in exposure rates, and providing additional evidence documenting its significant impact on their health.

The study used data from the 2007-2012 National Health and Nutrition Examination Survey (NHANES). They examined data on adolescents who did not report an asthma diagnosis, who were not current smokers, and who had serum cotinine levels ≤ 15 ng/mL to exclude active smokers. Disparities in exposure levels were found, with the highest rates of exposure among those in a family with income < 130% of the poverty level. This exposure does impact their lung function—with higher cotinine levels associated with lower FEV1 assessed as either a percentage of the predicted value or as a z score. This raises concern about their risk for developing obstructive lung disease as they get older. Although reasons for hospitalization were not documented, adolescents with evidence of tobacco smoke exposure had a higher number of hospital stays than those with no evidence of tobacco smoke exposure, and those with the highest cotinine levels had the highest risk for hospitalization.

The researchers also found that 39% of these non-asthmatic, nonsmoking adolescents had serologic evidence of tobacco smoke exposure, although only 10.9% reported in-home exposure. It is likely that the rates of in-home exposure are an underestimate. NHANES assesses tobacco smoke exposure as “Does anyone who lives here smoke cigarettes, cigars, or pipes anywhere inside this home?” Smokers who live in the home but consider themselves as smoking outside of the home would likely answer no to this question, although they could still be a source of exposure to the adolescent. The National Health Interview survey reports that the rate of smoking among adults, 25 to 44 years, was 24% in 2011.This would suggest that a substantial portion of the nonsmoking adolescents’ tobacco smoke exposure could be from family or household members who smoke but “not inside the home.” If we assume that the rate of smoking among young adults is the rate of homes with one or more smokers, that still leaves about 15% of their sample whose source of exposure was most likely from sources outside of the home and close family members. It might have been at friends’ homes, sporting events, places of leisure, at their jobs, and/or at school.

As a large, nationally representative sample of the US noninstitutionalized population, NHANES has excellent generalizability; however, the data sets used are 7 to 12 years old. A lot can change in that time. Their data largely precede the e-cigarette epidemic, which has substantially changed the landscape of tobacco product use and exposure among young people. That has both pluses and minuses. It gives confidence that their findings reflect the impact of involuntary tobacco smoke exposure from combustible tobacco products. However, the e-cigarette epidemic is now threatening the health of our young people. Rates of current e-cigarette use among high school students have skyrocketed from 1.5% in 2011 and 2.8% in 2012 to 27.5% in 2019 (National Youth Tobacco Survey data). Anecdotal reports are that you cannot walk into a high school bathroom without being exposed to e-cigarette emissions. The e-cigarette industry has developed and is promoting devices specifically designed for use where its use is prohibited (stealth vaping). Adolescents who do not use e-cigarettes are likely to have a difficult time avoiding involuntary exposure to their emissions.

The research base on the impact of involuntary exposure to e-cigarette emissions is just starting to develop. There is substantial reason to be concerned that involuntary exposure to e-cigarette emissions has substantial deleterious health effects. The emissions do contain carcinogenic and toxic substances. Heating and aerosolization of the e-liquid can produce toxic and carcinogenic aldehydes—including formaldehyde and acetaldehyde, polyaromatic hydrocarbons, and metallic nanoparticles. Laboratory studies of e-cigarette emissions demonstrate risk for endothelial damage, DNA damage, and oxidative stress from e-cigarettes. The liquids used in e-cigarettes have been demonstrated to reduce cell viability in a dose-dependent manner. Adverse effects of involuntary exposure to e-cigarette emissions as reported to the Food and Drug Administration include asthma exacerbations, bronchitis, cough, difficulty breathing, and pneumonia.

The findings reported by Dr. Merianos and her colleagues bring our attention back to just how important tobacco control measures are to protect the health of our next generations. It is particularly concerning given just how many adolescents are exposed and how that exposure impacts their health. Unfortunately, these are not surprising findings.

These findings show that we are not doing a good enough job in protecting our youth from tobacco smoke exposure. There is a substantial evidence base for tobacco control measures that work. In December 2019, the United States raised the age for sale of tobacco products to 21 years. This is an important accomplishment; however, much more is needed. Forty-six states in the United States received a grade of F by the American Lung Association for tobacco prevention and cessation funding. Twenty-two states still lack comprehensive smoke-free air laws. Do we have the political fortitude to go the distance? The next generations are depending on us.


Note: Content was edited for style and length

Click here to read the research study.

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