You’ve heard of second-hand smoke, but have you heard of third-hand smoke?
Thirdhand smoke is the smoke and chemicals that stick to indoor surfaces after cigarettes have been smoked in a room. The chemicals, including nicotine, can be re-released again into the environment–which means that nonsmokers can be exposed to harmful chemicals and carcinogens even years after smoking has been stopped in the environment.
In a randomized clinical trial published in the Journal of American Medical Association late last month, thirdhand smoke was investigated with 4 healthy nonsmoking volunteers. They were exposed to thirdhand smoke for 3 hours and samples of the skin cells lining the nasal passages were studied for changes in gene expression.
They found that even a brief exposure to thirdhand smoke had a negative effect on mitochondrial activity within the cells. The smoke caused cell survival responses and there was increase in harmful oxidation in the mitochondrial proteins. Antioxidant concentrations of glutathione was increased which suggests that the cells were reacting to high levels of reactive oxygen species (ROS, or free radicals). All of this happened within a 3-hour exposure to third-hand smoke.
One of the pathways that was involved was the Akt pathway which is the activation of serine/threonine kinase. This specific pathway for cellular survival can become active after exposure to nicotine within just minutes of exposure and researchers found the third-hand smoke also affected this pathway.
This study points out the need for longer-term studies on the effects of thirdhand smoke in humans, as the sample size and duration of the study did not address what happens when people are exposed for many years. It is a startling reminder of the changes and adaptations our bodies go through when we expose ourselves, sometimes unknowingly, to the toxins surrounding us.
Pozuelos GL, Kagda MS, Schick S, Girke T, Volz DC, Talbot P. Experimental Acute Exposure to Thirdhand Smoke and Changes in the Human Nasal Epithelial Transcriptome: A Randomized Clinical Trial. JAMA Netw Open. 2019;2(6):e196362. doi:10.1001/jamanetworkopen.2019.6362