Passive smoking may cause mutations in sperm

Studies on mice by the International Agency for Research on Cancer suggest that males exposed to passive smoke can cause mutations in the DNA of their sperm and such genetic deformities could then be passed onto their children. John Holden reports.

Smokers do not have it easy. Between price hikes, advertisement bans and unrelenting scientific research into the harmful effects of tobacco, it is hard not to feel some sympathy for those addicted to one of the difficult habits to kick known to man.

Long gone are the days when a celebrity having a puff would be seen in a positive light. The campaign to make smoking ‘un-cool’ has definitely been a success.

Now the damage being done to non smokers through second hand smoke has been highlighted once more through new research. In a study carried out for the National Academy of Sciences in the USA, Francesco Marcetti and his research team of the Lawrence Berkeley National Laboratory in California, exposed 32 mice to the amount of smoke produced by somewhere between three and 16 cigarettes, for up to 90 minutes per day for two weeks.

Such conditions were supposed to mimic the effects of various doses of direct and passive smoking as would be the case among humans. The sperm of the mice was then examined six weeks later.

Genomic mutation rates in mice that were not exposed to any kind of cigarette smoke was approximately 1.5 per cent. Mice exposed to the experiment simulating direct smoking was between four and five per cent while those exposed to the corresponding simulation for passive smoking had an average of between 2.4-4.6 per cent, depending on the doses.

According to the report, the data shows that “passive exposure to cigarette smoke can cause tandem repeat mutations in sperm under conditions that may not induce genetic damage in somatic cells…our data suggest[s] that paternal exposure to second-hand smoke may have reproductive consequences that go beyond the passive smoker."

Is any of this surprising? Not really. Decades of research have shown the links between smoking and cancer are irrefutable. With approximately 1.3 billion smokers currently worldwide, it is estimated that 5.4 million deaths a year are caused by tobacco.

While the harmful effects are well known the need to officially find evidence for and therefore recognise the damage caused by passive smoking among the population is significant. According to the Guardian Newspaper, Francesco Marcetti saw the results of the research as “compelling evidence in support of the argument that passive smoking should be regarded as a germ cell mutagen in humans."

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