Berkeley National Laboratory Researchers Demonstrate Thirdhand Smoke Link to Lung Cancer Development

Thirdhand smoke researchers find that exposure to thirdhand smoke during infancy and childhood increases the risk of developing lung cancer in adulthood.

January 6, 2020
By James Owens and Lydia Greiner, DrPH
Center Coordinator, Thirdhand Smoke Resource Center

Firsthand smoke and secondhand smoke are familiar to most of us, but thirdhand smoke is less well known. Thirdhand smoke, the toxic residue that remains after tobacco smoke disappears, accumulates on indoor surfaces and can enter the body through ingestion, inhalation, and absorption through the skin. Chemicals found in thirdhand smoke are known to cause a wide range of health effects, such as trigger asthma, cause headaches, slow wound healing, and decrease ability to fight infection.

Drs. Bo Hang, Jian-Hua Mao and Antoine Snijders, all from the Lawrence Berkeley National Laboratory, led an international group of researchers in an investigation of the relationship between early life exposure to thirdhand smoke and later life development of lung cancer. Dr. Hang explained that the research focused on early-life exposure because young children are at high risk for exposure to thirdhand smoke. There are several reasons for this increased risk, he said. “First of all, young children spend more time indoors, and they spend more time on the ground where they crawl around and basically act like a dust mop, absorbing thirdhand smoke through their skin. They also put their hands, and nearly everything else, into their mouths, swallowing thirdhand smoke. Finally, they breathe faster than an adult, and their bodies are smaller, so they breathe in more thirdhand smoke than an adult, relative to their body size.”

The study, published in the journal Clinical Science in February 2018, showed that thirdhand smoke exposure can increase the likelihood of developing lung cancer in later life. To conduct the study, the researchers placed cotton material contaminated with thirdhand smoke residue into the cages of one group of mice. They placed clean cotton material into the cages of another group of mice. All mice were four weeks old. After three weeks, the researchers removed all cloth material from the cages of the mice, which were now seven weeks old. Exposing mice between four to seven weeks old to thirdhand smoke in their cages is equivalent to exposing toddlers to thirdhand smoke in their homes. The researchers observed the mice 40 weeks after the exposure and found that the mice whose cages had the contaminated cloth materials were significantly more likely to have developed lung cancer. This age in mice is equivalent to the humans during adulthood. The results suggest that heavy exposure to thirdhand smoke early in life has a significant negative health impact in adulthood.

Recently, Drs. Hang, Mao, and Snijders authored a commentary, published in Nicotine & Tobacco Research, in which they discussed factors that might influence the relationship between early life exposure and development of cancer later in life. Dr. Snijders said, “The findings of an increased risk of lung cancer in late life associated with thirdhand smoke exposure at a young age should guide future research. We suggest future research should continue to investigate the relationship between early-life exposure to thirdhand smoke and development of cancer of all types and other diseases later in life. Such research will guide public health efforts to educate about the risks associated with thirdhand smoke exposure and policy efforts to protect from exposure to thirdhand smoke.”

Click here to read the original study.

Click here to read the commentary.

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