Toenails can show the likelihood of you developing lung cancer, scientists claim.
Toenail clippings can be used to predict the possibility of people getting cancer before the disease takes hold.
A team of US scientists, who tracked the health of 850 men for up to 12 years, measured nicotine levels in toenail clippings from smokers and non-smokers.
The team found that the toenails with the highest readings were three times more likely to get cancer than those with the lowest readings.
Surprisingly, more than 10 per cent of those with the highest levels of nicotine never smoked, which proves the damaging effects of passive smoking.
Toenails are a good indicator of long-term exposure to the disease because they grow at one centimetre a year, slower than fingernails.
The report read: “Our study shows toenail nicotine levels provide a biomarker that can predict the risk of lung cancer independent of reported smoking history.”
Just under 30,0000 people in England and Wales die from lung cancer every year. Smoking is the cause of about 90 per cent of cases.