Third-Hand Smoke

Have you ever been in the house of a smoker and felt as though you were covered in an invisible film—even though no one in the house was smoking?

This film now has a name and may be the latest health threat to you and your family. The name is "third-hand smoke", and researchers are looking into the possibility that it may be dangerous.

Third-hand smoke is a term coined in a study that appeared in the 2009 journal Pediatrics. The term was defined as "residual tobacco smoke contamination that remains after the cigarette is extinguished." Essentially, third-hand smoke is any tobacco residue that adheres to dust particles, furniture, carpets, drapes, and clothes as well as skin and hair.

Stemming from the belief outlined in the World Health Organisation Guidelines on Protection from Exposure to Tobacco Smoke which states that “there is no safe level of exposure to tobacco smoke”, the Pediatrics study set out to find a correlation between the harm third-hand smoke may do to children and no-smoking policies imposed in the home. Dr Jonathan Winickoff, who headed the study, believes it could significantly impact future tobacco messages, programs and guidelines.

What prompted this study?

There is a consensus in the medical profession that second-hand smoke is harmful. In fact, research has shown that second-hand smoke is deadlier than first-hand tobacco smoke because there are three to four times more toxins per gram in the smoke emitted than in the smoke consumed.

Ventilation has proven to be ineffective in removing second-hand smoke from buildings. The American Society of Heating, Refrigeration and Air-Conditioning Engineers (a renowned world leader in ventilation standards), concluded that “comprehensive smoke-free laws are the only effective means of eliminating the risks associated with second-hand tobacco smoke”.

Although many workplaces offer either restrictions to smoking or are smoke free, researchers were concerned about tobacco exposure in multi-family dwellings.

Recently, a study on tobacco exposure on children living in apartments concluded that these children were exposed to 45 percent more tobacco smoke than their counterparts living in detached homes. Although a particular unit may be smoke free, residents are still exposed to tobacco from apartments where smokers reside.

A toxic test

Taking concerns about third-hand smoke one step further, Berkeley Lab scientists performed testing in the cab of a heavy smoker’s truck to see if the residue left by tobacco could potentially become toxic to other occupants.

Finding that nicotine was the dominant substance in the residue, the scientists decided to see if adding nitrous acid (which occurs naturally in our atmosphere) would result in the formation of a carcinogen.

The results of the study yielded three main carcinogenic, tobacco-specific nitrosamines (TSNAs). The Berkeley Lab scientists state that nicotine can persist for weeks to months on indoor surfaces which would allow enough time to react with ambient nitrous acid. Although more work needs to be done in this area, this study shows that there is a potential health risk from exposure to the residue known as third-hand smoke.

Impact on children

The biggest concern about third-hand smoke is the potential it has to harm infants and small children.

Infants and children are closer to many surfaces where you may find third-hand smoke: carpets, tables and even their toys. Infants ingest over twice as much dust on a daily basis than adults do. If you factor in their higher respiration rates and lower body weights than adults, the risk potential increases dramatically.

Adding to the growing support that there may be a health risk associated with third-hand smoke, researchers at the Hohenstein Institute in Germany took the Berkeley Lab research another step further.

They wanted to see if nicotine and other neurotoxins that were absorbed into a smoker’s clothing could be absorbed by a baby’s skin. They tested their hypothesis with the simulation of a smoker going outside for a smoke and then returning inside to pick up their baby.

To do so they created a 3-D skin model that imitated a baby’s skin in cell composition and structure. After impregnating a piece of clothing with nicotine representing the tobacco residue, they placed the clothing on the skin model. The nicotine, released by perspiration, penetrated the outer layer of the skin into its deeper layers.

The experiment was repeated with donor adult skin; results were the same. The researchers also noted that the skin cells reacted to the nicotine. Some cells deformed and others died, and nerve cells were no longer able to connect to each other properly.

Regulating safety—now and beyond

Smoke-free laws have not hurt businesses including the hospitality industry. In fact, the impact has either been neutral or has resulted in an increase in business. This was found to be true not only in Canada, but in the US, Australia, the UK and Norway (as cited by the World Health Organization).

The World Health Organization (WHO) has monitored the success of smoke-free laws in many countries and makes recommendations including ensuring smoke-free workplaces, making sure that public place regulations are legislated and not voluntary and creating legislation that is comprehensive and enforceable.

Recently, Ontario has outlined goals for renewed tobacco control, including:

• minimizing the marketing of nicotine products
• preventing youth from becoming smokers
• protecting its population from involuntary exposure to tobacco smoke
• reducing the burden on the health care system

The recent studies on third-hand smoke support what governments and health care practitioners are already pushing for—complete smoke-free public environments and restrictions on smoking in residences and vehicles.

The best prevention of harm is elimination of the primary source. But it will be interesting to see how far governments can go to protect nonsmokers from third-hand smoke.

Social Costs of Smoking in Australia

According to the Australian Institute of Health and Welfare’s 2010 report, Drugs in Australia, tobacco smoking cost Australian society an estimated $31.5 billion in 2004-05. This can be broken down into tangible costs, such as health care, fires and lost productivity, and the intangible costs of pain and suffering—which make up the majority of social costs at 62 per cent. Of the tangible costs, the government sector was responsible for 8 per cent, while households and businesses bore 50 per cent and 42 per cent respectively.

Tobacco-related health expenditure includes primary healthcare and hospital costs, and also includes expenditures such as social marketing campaigns and Quitline—campaigns designed to prevent tobacco use. In 2008-09 Australian governments spent $55.6 million on these sorts of prevention programs.

Source: AIHW Drugs in Australia 2010