Have you ever heard of thirdhand smoke? Thirdhand smoke (THS) is the residue leftover from when exhaled smoke and smoke from the tip of burning cigarettes settles on surfaces such as clothing, hair, furniture, and cars. A new study published recently in JAMA Network Open from researchers at the University of California, Riverside details the danger that thirdhand smoke poses to us all.
"THS can resurface into the atmosphere and can be inhaled unwillingly by nonsmokers," said first author Giovanna Pozuelos. "It has not been widely studied, which may explain why no regulations are in place to protect nonsmokers from it."
THS, say the researchers, can harm epithelial cells in the respiratory system by stressing cells and causing them to fight for survival. "Our data show that cells in humans are affected by thirdhand smoke," said lead researcher Prue Talbot, a professor in the Department of Molecular, Cell and Systems Biology. "The health effects of THS, have been studied in cultured cells and animal models, but this is the first study to show a direct effect of thirdhand smoke on gene expression in humans."
In order to conduct the study, the researchers took nasal scrapes from four healthy nonsmokers who were voluntarily exposed to THS for three hours in a laboratory. From these nasal scrapes, the researchers were able to determine that 382 genes were significantly over-expressed while seven other genes were under-expressed.
These changes in gene expression are associated with oxidative stress and the researchers say there is concern over the consequences that THS could have for those exposed to it because oxidative stress can damage DNA. Those individuals who are exposed daily could be at risk for cancer and other consequences from altered gene expression.
A big part of the problem is the lack of awareness, say the authors. "Many people do not know what THS is," said Talbot, the director of the UCR Stem Cell Center. "We hope our study raises awareness of this potential health hazard. Many smoking adults think, 'I smoke outside, so my family inside the house will not get exposed.' But smokers carry chemicals like nicotine indoors with their clothes. It's important that people understand that THS is real and potentially harmful." The researchers hope to continue their work in order to better understand the threats hat THS pose.