Earwax – Current State of Knowledge

What is Earwax?

 

It has been called earwax, cerumen, gunk, cat earwax (Japan), and other names, not all complimentary.  It is technically called cerumen, and while often thought of as a hygienic nuisance, is far from this, actually representing one our body’s ingenious functional mechanisms, even though scientists are still not certain why we have earwax.

It is the intention of this review series of cerumen to show that this sticky secretion has not only clinical interest, but serves as a source of fascination as well.

What we see as earwax is a naturally-produced secretion that is reported to be a self-cleaning agent produced in the ears to protect, lubricate, and to provide antibacterial properties.  It consists of a mixture of water-soluble viscous secretions – sebum from sebaceous glands and less viscous secretions from modified apocrine sweat glands (Guest et. al, 2004), sloughed epithelial cells (dead skin) from the ear canal, hair, dust, and just about any other debris that happens to get “caught” and held together by this “sticky” fluid secreted by ceruminous and sebaceous glands near the opening of the ear canal. 

Earwax has also been reported to contain other substances, including lysozyme (an antibacterial enzyme), fatty acids, alcohols, cholesterol, and squalene, an oily liquid found in human sebum, especially in wet cerumen (Okuda, et. al., 1991).  Depending on how deeply one looks, cerumen also contains amino acids, neurostearic acid, cerotic acid, triglyceride, hexone bases, immunoglobulin, glycopeptide, copper, and other components (Chai and Chai, 1980).  Ironically, cerumen is actually not a wax at all.

According to Guest et al (2004), the primary components of earwax are shed layers of skin (60% consisting of keratin), saturated and unsaturated long-chain fatty acids, alcohol, squalene (12-20%), and cholesterol (6-9%) – Figure 1.

 

Suggested Purposes of Earwax

 

Cerumen or earwax is healthy in normal amounts and has been reported to provide beneficial properties such as:

• serving as a self-cleaning agent of the ear canal incorporating the following:
  • protection by
    • trapping and preventing objects from getting inside the ear and creating damage to the deep inner structures of the ear canal:
      • helps filter dust
      • small objects
      • protects delicate inner canal against irritation when water is in the canal
      • insects and water
• lubrication of the ear canal to prevent desiccation (drying), itching, and burning of the skin, especially because of the high lipid content of the sebum produced by the sebaceous glands.
• infection protection by slowing a range of strains of bacteria and fungi growth by incorporating some antibacterial properties to kill certain foreign organisms, whether it be wet or dry cerumen (Stone and Fulghum, 1984; Chai TJ and Chai TC, 1980). These antimicrobial properties are due principally to the presence of saturated fatty acids, lysozyme, and to the slight acidity of cerumen.  Interestingly, earlier reports as summarized by Chai and Chai (1980) had suggested that cerumen was unable to prevent infection, and even worse, that the rich nutrients of earwax actually supported luxuriant growth of bacteria and fungi.  Their research demonstrated that cerumen had antibacterial activity on each of ten strains of bacteria tested.
• self-cleaning of the ear canal by constantly and slowly moving earwax and debris out of the ear canal opening. People are mostly unaware of this cleaning process.  Cerumen is a component of the desquamation process where earwax and other debris (dead skin as an example) migrates laterally to the ear canal opening where it usually dries, flakes, and/or falls out.   This is a constant transporting action, assisted by chewing and mandibular (jaw) motion (Figure 2).
• maintains the ear canal’s acid balance, typically a pH of around 6.1 in normal individuals (Roland and Marple, 1997).

For certain, the presence of cerumen in the outer part of the ear canal, along with the turns of the ear canal, discourages small particles from reaching, and potentially damaging, the eardrum.

Earwax Types

 

Every person produces earwax, but the amount and type are believed to be genetically determined, just as are hair color and height.  The amount of earwax produced varies from person to person and has nothing to do with personal hygiene. Some people – mostly men and older people– produce a lot of earwax.

Most people have one of two types of earwax – (a) wet, sticky, and yellow-brown to dark brown or, (b) dry, crumbly/flaky and grayish-to-tan).  McDonald (2013) has reviewed a number of studies and reported that less than about 1% of the population have earwax that is intermediate or unclassifiable.  Earwax type is determined by a single gene variation.  The allele (one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome) for wet cerumen is dominant over that for dry cerumen.  Interestingly, Petrakis et al. (1986) found that the proportion of white women with dry earwax increased with age, suggesting that earwax type may not be determined solely by genetics.

 

Figure 3. Stages of wet cerumen from a light golden color on the left to increasing hardness and darker color as it ages.

Wet Cerumen – When fresh, wet cerumen is soft and yellow, but as it ages it may be brown or even black.  It may even look like dried blood (Figure 3).  Wet earwax is associated with warmer areas in Europe, Asia, and the Americas (Ohashi et al. 2011), suggesting that there seems to be something about cooler climates favoring the dry cerumen allele.  Earwax in children is usually softer and lighter in color than that produced by adults, and although they can produce quite a bit of earwax, it tapers off as they grow older to puberty.  It has been reported (Guest et al., 2004) that the consistency of wet type earwax is due to a higher concentration of lipid and pigment granules (50% lipid) in the substance than found in dry cerumen (30% lipid).

 

Figure 4. Dry cerumen (earwax), showing its crumbly/flaky, and grayish-white consistency. View into the ear canal.

Dry Cerumen – Dry cerumen is generally dry, crumbly/flaky, and grayish-white (Figure 4).  It seems to have originated by mutation in northeastern Asia about 2000 generations ago, and then spread outwards as favored by natural selection.  It is common in eastern Asia, and becomes much less common towards Europe, and is rare in Africa (McDonald, 2013).

A following post will continue this series on earwax, focusing next on earwax types.

References:

Chai TJ and Chai TC. (1980).  Bactericidal activity of cerumen, Antimicrobial Agents and Chemotherapy, Oct. pp. 638-641.

Guest JF, Greener MJ, Robinson AC, and Smith AF. (2004).  Impacted cerumen: composition, production, epidemiology and management.  Q J Med. 97-477-488.

Ohashi, J., I. Naka, and N. Tsuchiya. 2011. The impact of natural selection on an ABCC11 SNP determining earwax type. Molecular Biology and Evolution 28: 849-857.

Okuda I, Bingham B, Stoney P, and Hawke M. The organic composition of earwax.  (1991).  J. Otolaryngology, Jun:20(3):212-215.

Petrakis, N.L., S. L. Wiesenfeld, and L. Flander. 1986. Possible influence of age on the expression of the heterozygous cerumen phenotype. American Journal of Physical Anthropology 69: 437-440.

Roland PS, and Marple BF.  (1997).  Disorders of the external auditory canal.  J Am Acad Audiol. Dec;8(6):367-378.

Stone M, and Fulghum RS.  (1984).  Bactericidal activity of wet cerumen, Ann Otol Rhinol Laryngol, Mar-Apr;93(2 Pt 1):183-186.

*feature image from Wikipedia

 

Wayne Staab, PhD, is an internationally recognized authority on hearing aids. His professional career has included University teaching, hearing clinic work, hearing aid company management and sales, and extensive work with engineering in developing and bringing new technology and products to the discipline of hearing. Dr. Staab is the Founding Editor of Wayne’s World and served as the Editor-In-Chief of HHTM from 2015 to 2017.