Third-hand smoke may harm my children

Nicotine that accumulates on indoor surfaces long after a person has put out their cigarette is converted into cancer-causing chemicals, according to US scientists.

Researchers at the Lawrence Berkeley National Laboratory discovered that the nicotine in so-called third-hand smoke reacts with a common indoor air pollutant, called nitrous acid, to form dangerous chemicals.

Lab tests using cellulose surfaces to mimic indoor materials exposed to smoke, revealed that levels of carcinogenic tobacco-specific nitrosamines (TSNAs) increased by 10 times after three hours of exposure to nitrous acid, which is mainly emitted by un-vented gas appliances. These included cancer-causing chemicals such as NNA, NNN and NNK.

Tests on surfaces inside the truck of a heavy smoker confirmed there were high levels of TSNAs here as well, as a result of nicotine reacting with nitrous oxide from the vehicle's engine.

Ed Yong, Cancer Research UK's head of health information, commented: "This is an interesting piece of research that adds the possibility of an extra level of harm from tobacco smoke. However, this study doesn't tell us what threat, if any, third-hand smoke could pose to our health.

"There is clear evidence about the harmful effects of secondhand smoke to children, especially in homes and cars. The most important step parents can take to protect their families from the dangers of cigarette smoke is to make their homes and cars smokefree."

Hugo Destaillats, a chemist at Berkeley Lab's Indoor Environment Department, explained that burning tobacco releases nicotine vapour which clings to surfaces such as walls, floors, carpets and furniture – sometimes for months at a time.

"Our study shows that when this residual nicotine reacts with ambient nitrous acid it forms carcinogenic tobacco-specific nitrosamines or TSNAs," he confirmed.

The scientist added that TSNAs are "among the most broadly acting and potent carcinogens present in unburned tobacco and tobacco smoke".

Author Mohamad Sleiman revealed that TSNAs form rapidly and warned that third-hand smoke "represents an unappreciated health hazard through dermal exposure, dust inhalation and ingestion".

The study authors, whose findings are published in the Proceedings of the National Academy of Sciences, believe that the risk may be highest for infants and toddlers, as these are most likely to inhale dust or touch contaminated carpet or clothes.

Paul Charlson, GP from Brough

I think there comes a point when people should stopping worrying – and this is it.

Your children are unlikely to come to harm in this situation. There are some fears about third-hand smoke but there is little in the way of reliable research on the subject and whether it is harmful.

It is established that smokers do contaminate the environment and that children are at higher risk of exposure from residual third-hand smoke than adults because of the way they interact with the world. However, the risk to health has not been quantified.

I suspect there are far greater risks to your children's health such as going in your car to visit your mother-in-law or crossing the road, so I think you need to put it in perspective alongside life in general.

I would suggest that you do not mention it to your mother-in-law as it may not be received well and there is no point in starting a war over very little.

Elaine Douglas, A chartered psychologist who specialises in family and child relationships

Third-hand smoking is something that has come to the fore quite recently but I also think that this is one of those issues that needs further investigation, and I don't think that you should jump to immediate conclusions or panic until you have looked into this properly.

As far as I am aware, the notion of third- hand smoking comes from one piece of research in the US. A cross-section of people (both smokers and non-smokers) were asked whether they felt that there could be a danger from residual toxins on upholstery, carpets, the interior of cars, etc. The results seemed to suggest that a majority of people felt that this could be the case.

I think that the key issue here is "they felt" that it could be harmful.

It is something that I feel you shouldn't bring up with your mother-in-law. It would seem that she is very conscious of protecting her grandchildren, and, at the moment, because this research is in its infancy, you could create problems between you if you bring up the subject.

Cary Cooper, Professor of Organisational Psychology and Health at Lancaster University

I am not an expert on passive or third-hand smoking and the direct implications for health, but I would have thought the biggest risk is if she smoked when the children were around and in an enclosed space.

I don't know the research about smoke residue on inanimate objects and their associated risks, but I am sure you could find this out by contacting the British Heart and Lung Foundation or some other credible source, or maybe even on the web, where health data abounds from relevant health authorities.

Obviously, it is better getting the information first and then somehow, in a socially skilled way, communicate with your mother-in-law if the evidence indicates there may be a risk you are not prepared to take.

But rushing in with this will only undermine your relationship with your mother-in-law, particularly when she deliberately doesn't smoke when they are around.

Dr Carol Burniston, Consultant Clinical Child Psychologist

While your children's health is your priority, I presume that you also wish the best of health for your mother-in-law.

She is, of course, an adult and may have very fixed ideas about her own smoking habits. However, you could emphasise how you would like her to be around in yours and your children's lives for a long time and that this is more likely if she decides to give up smoking.

The message you and your husband decide to convey may be better coming from him as he is more closely related to his mother and may know how to communicate with her without causing an argument.

You do need to consider the possibility of upsetting your mother-in-law; is it more important to have her support in child care or to have her stop smoking?

You have made a choice to be at work rather than care for them full-time. You cannot have absolute control when you are not present, and this issue is one of the tensions working mothers have to deal with.