Measuring the nicotine content in toenail clippings can help predict a woman's heart disease risk, a US study in nurses suggests.
Analysis of toenails from more than 62,500 women showed double the level of nicotine in those with heart disease than those without the condition.
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Antibiotics 'no good' for sinus bug ... said the test may be more accurate than simply asking a person about their smoking history.
It is well established that smokers have a higher risk of heart disease.
There are existing tests for the presence of nicotine in the body, for example testing the amount of nicotine breakdown products in saliva or urine, but they only reflect recent exposure to cigarette smoke.
Study leader, Dr Wael Al-Delaimy said because toenails grow slowly - at a rate of around 1cm a year - they may offer a longer-term estimate of a person's total exposure to tobacco smoke.
And would take into account exposure to passive smoking and smoking habits such as how much smoke a person inhales with each puff.
Exposure
Over the period of the study 900 women were diagnosed with heart disease.
The women in the top fifth for toenail nicotine content were thinner, less active, heavier drinkers, and more likely to have high blood pressure or diabetes, as well as a family history of heart attack, compared to those with less nicotine in their toenails, the researchers found.
After taking other risk factors into account, they estimated that those with the top fifth levels of nicotine had almost four times the risk of heart disease than those in the bottom fifth.
The American Journal of Epidemiology study also reported the nicotine contained in toenails was a risk factor for heart disease independently of the number of cigarettes a person smoked.
Dr Al-Delaimy, a researcher at the University of California, San Diego, said: "The use of toenail nicotine is a novel way to objectively measure exposure to tobacco smoke and could become a useful test to identify high-risk individuals in the future."
Ellen Mason, a cardiac nurse at the British Heart Foundation (BHF) said the study emphasised that smokers are storing up health problems for the future.
"Men and women who smoke are around twice as likely to suffer a heart attack in their life time as those who don't, and quitting smoking is one of the most effective ways to reduce this risk.
"People using nicotine replacement therapy should not be alarmed by this study as it is the other chemicals inhaled when smoking, such as carbon monoxide that cause the risk of heart disease, not nicotine."
(BBC)
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