Earwax is "a neglected body secretion," according to researchers at Monell Chemical Senses Center in Philadelphia, PA. A new study shows that, as well as giving different odors corresponding to ethnic group, earwax could store other other useful personal information.

A mixture of secretions from sweat glands and the fatty byproduct of sebaceous glands, earwax is usually a wet yellow-brown wax or a dry white wax.

This wax makes its way to the opening of the ear and is usually washed away when we have a shower or bath.

But earwax does have some beneficial properties.

It traps and prevents dust, bacteria and small objects from getting inside the ear and damaging it, and it can protect the delicate ear canal from irritation when water is in the canal.

Genetic link between underarm odor and earwax

The Monell Center became interested in the properties of earwax after discovering that variations in a gene known as ABCC11 are related to whether a person has wet or dry earwax. This gene is also linked with underarm odor production.

"Our previous research has shown that underarm odors can convey a great deal of information about an individual, including personal identity, gender, sexual orientation and health status," says study lead author George Preti, PhD, an organic chemist at Monell. "We think it possible that earwax may contain similar information."

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Earwax is usually a wet yellow-brown wax or a dry white wax produced by sweat and sebaceous glands.

Given that differences in underarm odor can carry this level of personal detail, Preti wanted to see if earwax odor also has characteristics specific to ethnicity.

Preti's team collected earwax from 16 men - eight of these were white and eight were of East Asian descent. The samples were placed into individual vials that were heated for 30 minutes.

Once heated, the earwax began to release airborne molecules called "volatile organic compounds" (VOCs).

The VOCs - which are odorous - were then collected from the vials using a special absorbent device. A technique called "gas chromatography-mass spectrometry" was used to analyze the chemical make-up of these molecules.

White men produce more odorous earwax than East Asian men

Although 12 different types of VOC were found across all the earwax samples, the amounts of these VOCs seemed to vary according to ethnic background. The white men in the study had greater amounts of 11 of the VOCs than the East Asian men in the study.

East Asian and Native American people were already known to have a form of the ABCC11 gene that causes the dry type of earwax and produces less underarm body order, compared with other ethnicities.

"Odors in earwax may be able to tell us what a person has eaten and where they have been," says Preti. "Earwax is a neglected body secretion whose potential as an information source has yet to be explored."

The study notes that at least two odor-producing diseases - maple syrup urine disease and alkaptonuria - can be identified in earwax before they can be detected in blood or urine analyses. Further research from the Center will examine the possibility that analysis of earwax could be useful in detecting conditions before they show up in more traditional tests.

The ABCC11 gene is also associated with breast cancer. In 2009, Japanese scientists found that underarm odor and earwax could alert doctors to women who were carrying this gene and who therefore have increased risk of breast cancer.