Wednesday, May 23, 2007

The dangers of secondhand smoke (2)

It happens all the time. A smoker nearby lights up. I guess that you say nothing and just move away if possible. That's what most non-smoking people do (me included) in most of such situations. Only five or six in a hundred Australians would ask the person to stop smoking, according to a representative telephone survey in more than four thousand non-smokers. And Australians have a reputation of being outspoken. The survey also shows that nearly half of the persons would agree to be exposed to secondhand smoke if a smoker would ask them this question. It seems that a considerable part of the population is very unlikely to protect itself from the dangers of secondhand smoke. Therefore, smoke-free policies and laws are required as the study authors point out. I strongly support this opinion. - (Picture by Lottery Monkey @ Flickr)

Growing evidence for dangers

This week I have found a number of studies that add new evidence and insight. One of these is a Taiwanese study about the effect of secondhand smoke on four hundred children. It is most interesting because the danger of passive smoking could not be detected at first sight but clearly showed up at a closer look. In a first analysis, secondhand smoke seemed not to increase wheezing in exposed children. Only a second look at the genes revealed the previously hidden effect.

Details, in brief: In one gene that is responsible for a certain enzyme two variants have been detected. Children carrying the ile-variant are more susceptible to asthma even if not exposed to secondhand smoke. Exposure does not further increase this risk. On the other hand, children carrying the val-variant have a low ashma risk when not exposed, and exposure to secondhand smoke does significantly increase this risk.

Early exposure, late effects

Exposure to secondhand smoke before birth, because a pregnant woman smokes, has effects that can be detected twenty years later: The risk of hyper-sensitive airways that may cause asthma is six to seven times higher than in children of non-smoking mothers. If they grow up in a smoking home they are also seven times more likely to smoke themselves twenty years later. This is an indirect but very important effect of secondhand smoke.

While a mother-to-be should not smoke, she is also well-advised to stay away from secondhand smoke. A study in more than eightteen thousand UK babies has shown that passive smoking mothers give birth to babies lower in weight. On statistical average, the difference is only about one percent of birth weight. But it may be an important percent. After all, every mother wants to give her newborn the very best start.

Read more
The dangers of secondhand smoke (1)
Passive smoking (Wikipedia)

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