You might not think that earwax is very interesting but researchers at the Monell Center in Philadelphia would disagree. They've found that plain old earwax just may be an overlooked source of significant personal information, just like -- you know -- underarm odors.
"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," said study lead author George Preti, PhD, an organic chemist at Monell. "We think it possible that earwax may contain similar information."
Preti's interest in earwax was piqued by the finding that a small change in a gene known as ABCC11 is related both to underarm odor production and also to whether a person has wet or dry earwax.
It turns out that individuals of East Asian (e.g., Chinese, Korean and Japanese) and Native American descent have a form of the ABCC11 gene that codes both for dry-type earwax and also for reduced underarm body odor compared to other ethnic types, who typically produce a wet-type ear wax and greater body odor.
You may not have thought much about this but earwax, scientifically known as cerumen, is a mixture of secretions from specialized sweat glands with fatty materials secreted from sebaceous glands.
To explore whether earwax has a characteristic odor, the researchers collected earwax from 16 healthy men: eight Caucasian and eight of East Asian descent. Each sample was placed into a vial, which was gently heated for 30 minutes to promote release of airborne molecules known as volatile organic compounds ( VOCs), many of which are odorous.
The analysis revealed 12 VOCs were consistently present in the earwax of all the men. However, the amount of VOCs varied as a function of the subject's ethnic background, with Caucasians having greater amounts of 11 of the 12 VOCs than East Asians.
"In essence, we could obtain information about a person's ethnicity simply by looking in his ears. While the types of odorants were similar, the amounts were very different," said study lead author Katharine Prokop-Prigge, a Monell chemist.
The researchers suspect that the fatty nature of earwax makes it a likely repository for lipid-soluble odorants produced by certain diseases and the environment.
Prokop-Prigge points out that at least two odor-producing metabolic diseases (maple syrup urine disease and alkaptonuria) can be identified in earwax before they can be diagnosed using traditional techniques such as blood and urine analysis.
"Odors in earwax may be able to tell us what a person has eaten and where they have been," said Preti. "Earwax is a neglected body secretion whose potential as an information source has yet to be explored."
The study is being published in the Journal of Chromatography B.