Thirdhand Smoke Residue Impacts Children's Nicotine Exposure

Melinda Mahabee-Gittens, MD, MS

While smoking and exposure to secondhand smoke have long been known to cause health problems, investigators have found that thirdhand smoke—the residues that linger after smoke clears—exposes children to pollutants like nicotine and may be linked to respiratory issues.

All children in the study had detectable levels of nicotine on their hands, based on testing wipes used to wipe their dominant hands (geometric mean [GeoM] = 86.2 ng/wipe; range = 3.5-2190.4/wipe).

Children between 2 and 4 years of age had significantly higher levels of nicotine on their hands than children in younger and older age groups. The “increased mobility, exploratory behavior, decreased sleeping time, and increased contact with polluted surfaces,” of toddlers may account for the high levels of nicotine wrote study authors, led by Melinda Mahabee-Gittens, MD, MS, attending physician, Cincinnati Children’s Hospital Medical Center, and Ashley Merianos, PhD, assistant professor, University of Cincinnati.

Additionally, investigators found that even when caregivers reported that no cigarettes were smoked around the child in any location (28.0% of children) or in the home (40.7% of children), those children still had hand nicotine levels averaging 82.3ng/ml and 59.7ng/ml, respectively.

"It just goes to show that indoor smoking bans don't necessarily protect children from tobacco smoke exposure and related pollutants, such as thirdhand smoke," said Merianos in a statement.

Ashley Merianos, PhD

"It also shows that exposure to tobacco smoke toxicants is more widespread than previously thought because exposure in children is not limited to inhaling secondhand smoke," added Mahabee-Gittens.

The study included 104 pediatric patients, ages 0 to 17 years, who visited the Cincinnati Children's Pediatric Emergency Department between April 2016 and August 2017 with complaints potentially linked to tobacco smoke exposure. Each participant had at least one caregiver who smoked.

Caregivers were asked about their own smoking behaviors, the number of smokers who lived with the child, the number of cigarettes smoked per day by caregivers, the number of cigarettes smoked around the child in any location (such as in the home and the car) and the number of cigarettes smoked around the child inside the home.

All children had a health complaint potentially related to thirdhand smoke exposure. The most common of these were cough/congestion (n = 87, 83.7%), otalgia (n = 33, 31.7%), and wheezing or difficulty breathing (n = 31, 29.8%). The most common past medical history was asthma, which affected 19.2% of participants.

Children with coughs or congestion had significantly higher nicotine levels (GeoM = 97.7 ng/wipe) than children without coughs or congestion (GeoM = 59.0 ng/wipe, P = .01), even when controlled for age and caregivers’ cigarettes/day.

"Future work should explore the associations of hand nicotine and age to determine how children's changing interactions with their environment and behaviors contribute to increased nicotine in 2- to 4-year-olds, whether handwashing decreases the risk and whether increased levels are associated with increased [secondhand smoke-related] clinical illnesses," wrote investigators.

Merianos stressed that these findings are preliminary and that more research is necessary. “There's a paucity of literature available on the impact that thirdhand smoke has on health effects in children."

The study, “Nicotine on Children’s Hands: Limited Protection of Smoking Bans and Initial Clinical Findings,” was published in Tobacco Use Insights.