‘Third-hand smoke’ can cause serious health problems, U.S. study warns

We’ve all heard about the detrimental effects of smoking cigarettes and inhaling second-hand smoke, but a new U.S. study reveals that exposure to third-hand smoke — yes, it exists — can create health problems such as hyperactivity, liver and lung damage, and delay the body healing itself.
According to a study from the University of California, so-called third-hand smoke consists of second-hand smoke residue that gets left on the surfaces of objects, which then ages over time and becomes increasingly more toxic — leading to nicotine exposure levels that are, in fact, similar to what smokers are exposed to.


“We studied, on mice, the effects of third-hand smoke on several organ systems under conditions that simulated third-hand smoke exposure of humans,” said Manuela Martins-Green, who led the study, published this week in the journal PLOS One. “There is still much to learn about the specific mechanisms by which cigarette smoke residues harm non-smokers, but that there is such an effect is now clear.”
Those especially at risk of third-hand smoke include children, spouses of smokers and workers in environments where smoking has been allowed. Homes of smokers are often highly contaminated with third-hand smoke, existing on surfaces and in dust, which can even linger long after smokers have moved out. That last conclusion gives extra credence to the already established idea that smoking reduces the value of a piece of real estate.
Children who live with one or two adults who smoke in the home, says the study, are absent 40% more days from school due to illness than children who do not.
“Children in environments where smoking is, or has been allowed, are at significant risk for suffering from multiple short-term and longer health problems,” said Martins-Green, “many of which may not manifest fully until later in life.”
Among other results from the mice, third-hand smoke was found to increase lipid levels in the liver, as well as non-alcoholic fatty liver disease — a precursor to cancer and potential contributor to cardiovascular disease.
The lungs also produced excess collagen and high levels of inflammatory cytokins (small cell-signalling proteins), which presents risks such as asthma and fibrosis. Skin also healed poorly, similar to human smokers who have just gone through surgery.
The first town to order a complete ban on indoor smoking, in all public spaces from restaurants to bars, was San Luis Obispo, California, in 1990. It was the first municipality in the world to do so. In Canada, the Non-Smokers’ Rights Association Smoke-Free Laws Database includes a list of all the laws in effect across the country protecting people from second-hand and third-hand smoke.