Acute exposure can elevate biomarkers associated with contact dermatitis and psoriasis.
A new study, led by a team of researchers at the University of California, Riverside found that human skin exposed to thirdhand smoke (THS) can initiate mechanisms of inflammatory skin disease.1 Skin is the largest organ to absorb THS and receives the most exposure. The study, published in the journal eBioMedicineis the first to be performed on humans exposed dermally to THS.
The clinical investigation involved 10 healthy, non-smoking adults. For 3 hours, each participant wore clothing saturated with THS and walked or ran on a treadmill for at least 15 minutes each hour, to sweat and increase uptake of THS through the skin. Investigators took blood and urine samples at regular intervals (0,3, 8, 24 hours after exposure) to identify protein changes and markers of oxidative stress induced by the smoke. Control exposure participants wore clean clothing.
The THS 22-h proteomics pathways revealed inflammation of organ (p=3.09 × 10−8), keratinization of the epidermis (p=4.0 × 10−7), plaque psoriasis (p=5.31 × 10−7), and dermatitis (p=6.0 × 10−7). Two activated canonical pathways were production of nitric oxide and reactive oxygen in macrophages (z-score=2.646), and interleukin (IL)-8 signaling (z-score=2.0).
Thirdhand smoke consists of the tobacco residue from cigarettes, cigars, and other tobacco products that is left behind after smoking and builds up on surfaces and furnishings. Tobacco smoke is composed of numerous types of gases and particulate matter, including carcinogens and heavy metals, like arsenic, lead, and cyanide. Sticky, highly toxic particulates, like nicotine, can cling to walls and ceilings. Gases can be absorbed into dust in a room, carpets, draperies, and other fabrics or upholsteries.2
Study author and research scientist at Kite Pharma in California, Shane Sakamaki-Ching, said he found THS exposure caused elevated biomarkers of oxidative damage to DNA, lipids, and proteins; the biomarkers remained high when exposure ceased. Those biomarkers are associated with early-stage activation of contact dermatitis, psoriasis, and other skin conditions. He hopes the study will help physicians diagnose patients exposed to THS and help develop regulatory policies dealing with remediation of indoor environments that are contaminated by THS.
More studies on the effects of THS are planned. The researchers say they will next evaluate residues left by electronic cigarettes, that encounter human skin. For those studies, they say they will evaluate larger populations, and expose them to longer periods of dermal THS.
The study was supported by grants to Talbot and Schick from the Tobacco-Related Disease Research Program of California.
1. Sakamaki-Ching S, Schick S, Grigorean G, Li J, Talbot P. Dermal thirdhand smoke exposure induces oxidative damage, initiates skin inflammatory markers, and adversely alters the human plasma proteome. EBioMedicine. 2022 Oct;84:104256. doi:10.1016/j.ebiom.2022.104256
2. Northrup TF, Jacob P 3rd, Benowitz NL, et al. Thirdhand Smoke: State of the Science and a Call for Policy Expansion. Public Health Rep. 2016;131(2):233-238. doi:10.1177/003335491613100206