A pregnant woman exposed to cigarette smoke can pass on the harmful smoke constituents to the foetus
AS THE link between cigarette smoking and cancer and heart disease is more firmly established, scientists are increasingly looking at the impact a parent's smoking has on both the unborn and the growing offspring.
Two recent studies reveal that not only does a mother's active smoking expose her young children to the harmful effects of tobacco, but even if she is a passive smoker during her pregnancy, she can pass on cigarette smoke constituents to her unborn baby.
The first study examined the impact of passive smoking on 5 to 7 year olds in England and Wales (British Medical Journal, Vol 308, No 6925). Derek G Cook, a senior lecturer in epidemiology at the St George's Hospital Medical School in London and his colleagues there and in other hospitals in London analysed 4,043 children using cotinine -- a product formed when nicotine, a toxin present in tobacco, is broken down in the body. The doctors found it in their saliva as an indicator to quantify exposure to passive smoking.
They found that although cotinine concentrations were about 100 times lower in children exposed to cigarette smoke than that in adult smokers, even such concentrations could weaken the lungs and make children more prone to respiratory infections. In the long term, such low levels of exposure may lead to lung cancer, they say.
They found that parental smoking was by far the most important cause of exposure in these children. They discovered that it was the mother's smoking, and not the father's, that was more harmful, probably because mothers spend more time with their children.
The study revealed that exposure to cigarette smoke outside the home also had an impact on the children.
In another study, Canadian doctors measured the amount of nicotine and cotinine in the hair of the newborn, and in the hair of their passive smoking mothers (The Journal of the American Medical Association, Vol 271, No 8). They based their work on earlier studies that had shown that individuals exposed to passive smoking over a period of time accumulate nicotine and cotinine in their hair.
Chrisoula Eliopoulos of the Hospital for Sick Children in Toronto and her team say their study revealed that mothers with passive smoking exposure had 3 times more cotinine in their hair than mothers who were not exposed; further, the infants of the former also had similarly higher levels of cotinine than those of the latter.
The Canadian scientists claim that their study "is the first biochemical evidence that infants of passive smokers are at risk of measurable exposure to cigarette smoke".
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