Smoke damages the liver and brain; even THIRDHAND

Smoking and secondhand smoke exposure are known to be hazardous, but thirdhand smoke exposure, a relatively new term, may be just as dangerous. A study finds that thirdhand smoke can damage the liver and brain.

A group of scientists from the University of California, Riverside studied the health effects of thirdhand smoke on mice. For the study, they exposed mice for up to six months to a system in which their exposure to thirdhand smoke is similar to that of human exposure in the homes of smokers. They gathered brain, liver, and serum samples after one, two, four, and six months to examine the effects of thirdhand smoke exposure. Then, they examined biomarkers of damage and disease found in serum, and in liver and brain tissues. The goal of the study is to identify the minimum amount of time needed to cause physiological changes in mice when they are exposed to thirdhand smoke.

Thirdhand smoke is the residual contamination from tobacco smoke that stays in rooms even after smoking stops. It also remains on clothes even after you leave a place where someone smoked tobacco. Toxins from this exposure can be absorbed through the skin and by inhalation.

“THS [thirdhand smoke] is a stealth toxin, a serial killer,” says Manuela Martins-Green, professor and chair of the Department of Molecular, Cell and Systems Biology and leader of the study.

“We found a positive time-dependent significant correlation with increased time of THS exposure and the effects it had on all the variables we measured,” Martins-Green adds. “These biomarkers, once validated in humans, can be used as critical indicators of exposure to THS, and how long this exposure has occurred.”

The findings of the study reveals that exposure to thirdhand smoke can lead to liver damage as early as one month after the exposure. Moreover, two months of exposure to thirdhand smoke can lead to further molecular damage, while at four to six months, the damage can get worse. When the liver is damaged, it cannot function well and cannot properly detoxify the body, which causes more damage because of the toxins brought by thirdhand smoke. In addition, the mice displayed resistance to insulin after being exposed to thirdhand smoke for a long time.

As part of the study, the researchers have also analyzed the brains of the mice that were exposed to thirdhand smoke. They have discovered that there was an increase in the levels of stress hormones, such as epinephrine, one month after the exposure. The stress hormones have continued to increase over the course of the study, which eventually led to immune fatigue in the mice.

Martins-Green notes that even if their study has not been conducted on humans, people should be aware that places like hotel rooms, cars, and homes where smokers went are likely to be contaminated with thirdhand smoke. She also adds that most people are not aware that they are being exposed to thirdhand smoke, and a lot also do not believe in the adverse health effects that it can cause. Its toxins may be not be seen by the eyes, but can be smelled, stay on surfaces for years, and become resistant to strong cleaning agents. Moreover, they build up and age by reacting with the ambient air and become cancer-causing chemicals.

The people that are most at risk of thirdhand smoke exposure are children as they are always in contact with household surfaces. They often get contaminated with these toxins when they put their hands in their mouth and absorb them through skin exposure. (Related: Groundbreaking research exposes the serious health consequences of thirdhand smoke.)

The findings of the study have been published in Clinical Science. The study has been funded by the UC Tobacco-Related Disease Research Program.

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