By Islam El-Sakka
Scientists have discovered that human earwax, known medically as cerumen, can effectively stop insects from entering the ear canal without the use of chemicals, according to a study published in the journal Soft Matter.
Earwax Properties and Medical Advice
Earwax has a consistency between toothpaste and dough, can absorb twice its weight in water while remaining sticky, and was historically used by medieval artists as a paint binder. Medical experts advise against removing earwax, as ears are self-cleaning and cerumen lubricates the canal, fights infection, and traps debris. Cerumen impaction affects about 20% of Americans, leading to 12 million patient visits annually, often worsened by earbuds or hearing aids.
Insects as Common Ear Debris
While children often insert objects like Legos into their ears, adults frequently encounter insects such as ants, beetles, flies, or cockroaches. Physicians have long speculated that earwax evolved as a natural barrier against insects, but the physical mechanism remained unclear.
Experiments with Ants and Earwax
Researchers led by David Hu, a professor of mechanical engineering and biology at the Georgia Institute of Technology, conducted experiments using earwax collected from mammals and human volunteers. They coated the rim of a glass beaker with earwax to simulate an ant climbing into an ear canal. Ants are adept climbers, using foot spikes for rough surfaces and wet suction cups for smooth ones.
Findings and Implications
The study demonstrated that earwax physically prevents insects from climbing, offering a potential natural alternative to chemical repellents. The research focused on the physics of earwax as a soft solid rather than its chemical composition, revealing its effectiveness as a mechanical barrier.
