Exposure to third-hand smoke, the residues left behind by smoking that settle on surfaces, can also damage your respiratory system…

It’s well known that second-hand smoke is a health hazard, but now new research has highlighted the danger of third-hand smoke (THS).

Scientists from the University of California found that exposure to third-hand smoke can damage 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 third-hand smoke. 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 third-hand smoke on gene expression in humans,” says lead researcher Prue Talbot, a professor in the Department of Molecular, Cell and Systems Biology.

What is third-hand smoke?

It’s not strictly smoke, but the residues left behind by smoking.

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It’s the result of exhaled smoke and smoke emanating from the tip of burning cigarettes when it settles on surfaces such as clothing, hair, furniture, and cars.

Third-hand smoke can be inhaled

“THS can resurface into the atmosphere and can be inhaled unwillingly by non-smokers,” says Giovanna Pozuelos, the first author of the research paper and a graduate student in Talbot’s lab. “It has not been widely studied, which may explain why no regulations are in place to protect non-smokers from it.”


What happens when non-smokers are exposed to third-hand smoke

The researchers obtained nasal scrapes from four healthy non-smokers who had been exposed to THS for three hours. They then worked to get good quality RNA from the scrapes so that they could examine gene expression changes.

They found 382 genes were significantly over-expressed and seven other genes were under-expressed. They then identified pathways affected by these genes.

THS exposure increases cancer risk

“THS inhalation for only three hours significantly altered gene expression in the nasal epithelium of healthy non-smokers,” says Pozuelos. “The inhalation altered pathways associated with oxidative stress, which can damage DNA, with cancer being a potential long-term outcome. It’s extremely unlikely a three-hour exposure to THS would cause cancer, but if someone lived in an apartment or home with THS or drove a car regularly where THS was present, there could be health consequences.”

Because gene expression in the nasal epithelium is similar to the bronchial epithelium, these findings are relevant to cells deeper in the respiratory system.

THS linked to healthy cell death

The researchers also found that brief THS exposure affected mitochondrial activity. Mitochondria are organelles that serve as the cell’s powerhouses. If left unchecked, it would lead to cell death.

“Many people do not know what THS is,” says Talbot, “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.”


Source: University of California – Riverside via www.sciencedaily.com

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