Thirdhand Smoke Found to Increase Lung Cancer Risk in Mice
Source: Lawrence Berkeley National Laboratory
Summary: Researchers in a new study, have determined that early thirdhand smoke exposure is also associated with increased incidence and severity of lung cancer in mice.
Field studies in the U.S. and China have confirmed that the presence of thirdhand smoke (is a residual nicotine and other chemicals left on indoor surfaces by tobacco smoke) in indoor environments is widespread, and traditional cleaning methods are not effective at removing it. Because exposure to thirdhand smoke can occur via inhalation, ingestion, or uptake through the skin, young children who crawl and put objects in their mouths are more likely to come in contact with contaminated surfaces and are therefore the most vulnerable to thirdhand smoke’s harmful effects. Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory identified thirdhand smoke, the toxic residues that linger on indoor surfaces and in dust long after a cigarette has been extinguished, as a health hazard nearly 10 years ago. Now a new study has determined that early thirdhand smoke exposure is also associated with increased incidence and severity of lung cancer in mice. The study findings were published in the journal Clinical Science.
In this study, an experimental cohort of 24 A/J mice (a strain susceptible to spontaneous lung cancer development) was housed with scraps of fabric impregnated with thirdhand smoke from the age of 4 to 7 weeks. The dose the mice received was estimated to be about 77 micrograms per kilogram of body weight per day comparable to the ingestion exposure of a human toddler living in a home with smokers. Forty weeks after the last exposure, these mice were found to have an increased incidence of lung cancer (adenocarcinoma), larger tumors, and a greater number of tumors, compared to 19 control mice. Their work also sheds light on what happens on both a molecular and cellular level. If thirdhand smoke toxins damage DNA within cells and the damage is not repaired properly, it can give rise to mutations, which may lead to the cell becoming cancerous.
More Information: Bo Hang et al, “Short-term early exposure to thirdhand cigarette smoke increases lung cancer incidence in mice”, Clinical Science (2018). DOI: 10.1042/CS20171521