Scientists have long known that the residue from cigarette smoke clings to surfaces for weeks and even months. Now there is new research indicating that the film left by burning tobacco, when exposed to a chemical often found in the air, forms a brew of potent carcinogens that can coat clothing, dust particles and even human skin.
Children, who breathe in more dust for their body weight than adults, are most vulnerable to health problems from such “third-hand smoke,” the scientists said.
“We’ve identified a new risk for tobacco smoke,” said Lara Gundel, an environmental physical chemist at California’s Lawrence Berkeley National Laboratory, who is one of the study’s authors. “That risk is that third-hand smoke residues can get more dangerous over time.”
Smokers already know that smoking is harmful, says Michael Thun, a top epidemiologist at the American Cancer Society. Still, the new study “is useful for smokers to know. … If they have little kids, the choice is to smoke outside if [they] can’t stop smoking.”
The new findings come in part from a highly unorthodox laboratory — a 1966 pickup truck.
The truck belongs to a chain smoker recruited by Gundel and her colleagues. The smoker, whose identity is protected by confidentiality rules, commutes to work in the truck, puffing an average of 10 cigarettes a day along the way.
The scientists swabbed the pickup’s dashboard and found a cocktail of compounds that cause cancer. They also found compounds — not present in fresh tobacco smoke — that cause cellular changes linked to cancer.
The researchers then did experiments in a conventional lab, wafting an airborne chemical often found in rooms and cars over a surface painted with nicotine. That created the same noxious compounds found in the pickup.
These dangerous chemicals have plenty of opportunity to develop in places where someone regularly lights up. That’s because nicotine doesn’t conveniently blow away. Instead, it hangs around for a long time on walls, bed frames, dashboards and other surfaces.
As a result, those items can harbor the carcinogens that form when nicotine mixes with air. The risk could come from inhaling carcinogen-laden dust, or from touching clothing or furniture sprinkled with carcinogens, Gundel said.
“It’ll be on people’s clothes and skin,” she said, and the most vulnerable people are “kids crawling around on the carpets.”
Other experts cautioned — and Gundel agreed — that it’s not clear how significant the risk might be.
“It’s a little preliminary to get worked up about this particular route of exposure,” said Stephen Hecht of the University of Minnesota. “If I were a betting man, I would bet the [exposure to carcinogens] would be a lot lower than from secondhand smoke.”
“The public may have a sense of, ‘Where does it end?'” says Thun. “But it’s something that parents of small kids may want to pay attention to.”