Thirdhand smoke can remain on indoor surfaces indefinitely, causing potentially harmful exposure to both smokers and non-smokers. Acute exposure of the human skin to thirdhand smoke elevates biomarkers associated with the initiation of skin diseases, such as contact dermatitis and psoriasis, according to a study published in the journal eBioMedicine.
Sakamaki-Ching et al. demonstrated that acute dermal exposure to thirdhand smoke mimics the harmful effects of cigarette smoking, alters the human plasma proteome, initiates mechanisms of skin inflammatory disease, and elevates urinary biomarkers of oxidative harm. Image credit: Tumisu.
Thirdhand smoke is comprised of the residual tobacco smoke pollutants that remain on surfaces and in dust after tobacco has been smoked; are re-emitted into the gas phase; or react with oxidants and other compounds in the environment to yield secondary pollutants.
Some thirdhand smoke chemicals, including nicotine, react with environmental oxidants and produce secondary pollutants, such as tobacco-specific nitrosamines, that are harmful.
Thirdhand smoke can remain on indoor surfaces indefinitely causing potentially harmful exposure to both smokers and non-smokers.
The three main routes of thirdhand smoke exposure are inhalation, ingestion, and dermal. Skin is the largest organ to contact thirdhand smoke and may receive the greatest exposure.
“We found exposure of human skin to thirdhand smoke initiates mechanisms of inflammatory skin disease, and elevates urinary biomarkers of oxidative harm, which could lead to other diseases, such as cancer, heart disease, and atherosclerosis,” said Dr. Shane Sakamaki-Ching, a research scientist at Kite Pharma.
“Alarmingly, acute dermal exposure to thirdhand smoke mimics the harmful effects of cigarette smoking.”
The study involved the participation of 10 healthy, non-smokers who were 22 to 45 years old.
For three hours, each participant wore clothing impregnated with thirdhand smoke and either walked or ran on a treadmill for at least 15 minutes each hour to induce perspiration and increase uptake of thirdhand smoke through the skin.
The participants did not know the clothing had thirdhand smoke.
Blood and urine samples were then collected from the participants at regular intervals to identify protein changes and markers of oxidative stress induced by thirdhand smoke. Control exposure participants wore clean clothing.
“We found acute thirdhand smoke exposure caused elevation of urinary biomarkers of oxidative damage to DNA, lipids, and proteins, and these biomarkers remained high after the exposure stopped,” Dr. Sakamaki-Ching said.
“Cigarette smokers show the same elevation in these biomarkers. Our findings can help physicians in diagnosing patients exposed to thirdhand smoke and help develop regulatory policies dealing with remediation of indoor environments contaminated with thirdhand smoke.”
The thirdhand smoke exposures that the 10 participants were subjected to were relatively brief and did not cause visible changes in the skin.
Nevertheless, the molecular biomarkers in blood that are associated with early-stage activation of contact dermatitis, psoriasis and other skin conditions were elevated.
“This underscores the idea that dermal exposure to thirdhand smoke could lead to molecular initiation of inflammation-induced skin diseases,” Dr. Sakamaki-Ching said.
The authors plan to evaluate residues left by electronic cigarettes that can come into contact with human skin.
They also plan to evaluate larger populations exposed to longer periods of dermal thirdhand smoke.
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Shane Sakamaki-Ching et al. 2022. Dermal thirdhand smoke exposure induces oxidative damage, initiates skin inflammatory markers, and adversely alters the human plasma proteome. eBioMedicine 84: 104256; doi: 10.1016/j.ebiom.2022.104256
