If you can smell cigarette smoke in your house, hotel room, rental car or workplace, you may be damaging your health by exposure to third-hand smoke, a new study has found. Living, working or lodging in houses, offices, hotels and vacation rentals where cigarettes have been smoked may be as dangerous to your health as being an actual smoker, according to new research led by UC Riverside’s Manuela Martins-Green, who, along with colleagues from several other universities, conducted the first animal research on the effects of third-hand smoke. “This is the first study that unequivocally shows damage to organ systems by third-hand smoke,” Martins-Green said. A professor of cell biology in the laboratory of wound healing at UC Riverside, Martins-Green and her research team studied wound-healing in rodents exposed to the residue from cigarettes that remains in the air, dust and on structures long after a cigarette is extinguished. They found that re-emission of nicotine from contaminated indoor surfaces can lead to nicotine exposure levels similar to that of smoking. Earlier studies have established that third-hand smoke, which contains strong carcinogens, lingers in dwellings long after smokers move out and the place is cleaned, and that new occupants remain exposed to it. For example, nicotine can react with nitrous acid in the environment and form tobacco specific nitrosamines, which are carcinogens. It has also been reported that children living with one or two adults who smoke in the home, where second- and third-hand smoke are abundant, are absent 40 percent more days from school due to illness than children who did not live with smokers. In discussing the new study, which was published published Jan. 29 in the journal PLOS ONE, Martins-Green said more research will be needed and clinical trials conducted to establish whether third-hand smoke can actually cause the same damage to the liver and lungs as smoking. But the potential international ramifications on the value of older buildings, residential real estate, rental cars and homes of individuals may prove enormous.
Martins-Green’s team found that third-hand smoke damaged lungs and other organs in rodents and caused inflammation potentially linked to chronic diseases such as diabetes and respiratory conditions. The toxic residue from burned nicotine and its carcinogens deposit in the air, dust, ventilation systems, furniture and even drywall. Key findings noted by UC Riverside: • In the liver, third-hand smoke was found to increase lipid levels and non-alcoholic fatty liver disease, a precursor to cirrhosis and cancer and a potential contributor to cardiovascular disease. • In the lungs, third-hand smoke was found to stimulate excess collagen production and high levels of inflammatory cytokines (small proteins involved in cell signaling), suggesting propensity for fibrosis with implications for inflammation-induced diseases such as chronic obstructive pulmonary disease and asthma. • In wounded skin, healing in mice exposed to third-hand smoke showed many characteristics of the kind of poor healing observed in human smokers who have gone through surgery. • Finally, in behavioral tests, rodents exposed to third-hand smoke showed increased activity. “The mice were behaving differently than the control mice,” Martins-Green said. “These mice displayed hyperactivity.” “The latter data, combined with emerging associated behavioral problems in children exposed to second- and third-hand smoke, suggests that with prolonged exposure, they may be at significant risk for developing more severe neurological disorders,” Martins-Green said. “We didn’t expect to see what we saw, but that’s what research is about. The most surprising is the generalized affect, not just slow healing, but how generalized the problem is, how many areas were affected.” Third-hand smoke has been a concern long before it received its present name. The seed of the idea that cigarette smoke toxins might linger on room and car surfaces well after the smoke itself was gone was planted in 1953, when it was reported that smoke condensate painted onto mice caused cancer. Even Mom’s Hair Presents a Danger Is the damage from third-hand smoke reversible? If parents reupholstered an inherited chair of a smoker, for instance, would that be enough to remove the danger? “Well, we haven’t tested that,” Martins-Green said, but what the research now tells us is that “you not only have to quit smoking, but get rid of the things with second-hand smoke. You get [the toxins] by breathing it, by absorbing it in the skin, those children crawling around, running their hands through Mom’s hair, the third-hand smoke gets on their hands. The thing with children is they are much less able, with smaller livers, to detoxify.” A number of research programs are underway examining different aspects of third-hand smoke, THS for short. The Stratford, Conn., Health Department received a 2011 Healthy Community Grant from the EPA to reduce children’s exposure to THS through a community-based campaign to “educate residents about the dangers of the poisonous chemicals that stick around long after a cigarette has been put out,” explained the advocacy group GASP (Global Advisors Smoke-Free Policy). They have developed a toolkit that community partners can use to teach parents about the issue, and are providing free smoking-cessation classes. UC Riverside’s Martins-Green said the team’s findings would propel further research. “There is the satisfaction that the scientist has when we discover something and tell the world about it,” she said, “and then [see] how it will improve health.” The research was funded by a grant from the California Tobacco Related Disease Research Program.