The toenails may be a good indicator of the risk of lung cancer.
According to a new study, nicotine levels in the nails can fairly accurately predict the risk that has a smoker and a non-smoker exposed to passive smoke, "to develop the disease in the future.
The study, conducted at the University of California, San Diego, found that the toenails, which grow very slowly, provide a barometer of chronic exposure to tobacco snuff that has had an individual.
The research, published in American Journal of Epidemiology (American Journal of Epidemiology), found that men with higher levels of nicotine in their toenails showed 3, 5 times more likely to develop lung cancer than those with lower levels.
Scientists say levels of nicotine in the toenails are relatively stable compared with the urine or saliva.
This is because the nails grow very slowly, almost an inch a year.
Experts believe that this finding could lead to new tests to detect lung tumors.
"Whether you are a smoker or a nonsmoker exposed to passive smoke snuff, we can now measure to better exposure to smoke and to predict their risk," says Professor Wael Al-Delaimy, who led the study.
"The toenails can be stored at room temperature for many years. And may represent exposure to nicotine during the past year," says the scientist.
The scientists took samples of toenails of 850 men in 1987 when the experiment began.
We knew that the snuff was bad, but now we are learning that it is far more dangerous than we had previously established
Prof. Wael Al-DelaimyLas nails were analyzed to measure the levels of nicotine and scientists followed the participants for 12 years to see who developed lung cancer.
The results showed that those who developed the disease had, at baseline, an average nicotine level of about 0, 95 nanograms per milligram.
But those who did not develop the tumor had only 0, 25 ng per mg.
In addition, over 10% of men with higher levels of nicotine had never smoked.
This analysis reveals that some samples are also "hidden risks" that are passive smokers.
As the authors note, these results show that future studies to examine the risk of lung cancer should not rely solely on the smoking histories of the participants.
Should take into account other indicators such as levels of nicotine in the toenails, they add.
"We knew that the snuff was bad, but now we are learning that it is far more dangerous than we had previously established," says Professor Al-Delaimy. "And we are getting a better indicator of the true risk of the effects of snuff on the lung" agrega.El Lung cancer is the most common cancer in the world are diagnosed each year 1, 61 million new cases of the disease.
Most of these tumors are caused by the consumption of snuff.