Fingernails are made of keratin, carbon, nitrogen, and sulfur.
More Info: The primary component of human fingernails is the protein keratin. Secondarily, the cutaneous tips contain carbon, nitrogen and sulfur.
A study conducted by researchers at the University of Kiel and the University of Mainz, Germany found that female fingernails contain more sulfur and less nitrogen than those of their male counterparts. In both genders, with age, the proportional amount of carbon in fingernail increases.
New Drug and Alcohol Test
The composition of human fingernails can also reveal the recent eating and drinking history of an individual. A new test called the NailState and HairState EtG analyzes nail (or hair) samples to measure the amount of ethyl glucuronide that is present. The substance is a natural byproduct the metabolic breaking down of alcohol.
The U.S. Drug Testing Laboratories (USDTL) sampled 600 students and found that the correlation between this nail-hair measurement and the actual number of drinks consumed over 90 days was extremely accurate. The test was developed to help medical practitioners make informed diagnoses about how alcohol consumption may contribute to specific ailments and conditions.
An interesting sideline of the testing was that nail sampling was more reliable, and gender-independent, that hair testing. Researchers found that the large amount of hair styling products used by women tainted their ability to make as accurate a determination from female hair samples as they were able to from women's nails.
German Court Case
In January 2010, a court in Cologne, Germany made a ruling pertaining, among other things, to fingernails. A North Rhine-Westphalia Labor Court was responding to complaints by workers with a federal airport security contractor that their employer was demanding certain personal grooming standards.
In its ruling, the court determined that it was not unreasonable for the employer to require that worker fingernails be no longer than half a centimeter. However, the judgment decreed that the company could no longer order the kind of nail polish that female employees were allowed to display on their fingers.