點解會有耳油??

Ear wax (耳油)defined
Ear wax is a normal product of the ear which protects the skin of the ear from water and infection. Ear wax is formed from wax glands in the external ear canal as well as other components such as dead skin, sweat, and oil. The primary component of ear wax is keratin (derived from dead skin). Ear wax thus differs slightly from cerumen which is the secretory product of the ceruminous glands in the external auditory canal (Hawke, 2002).
Different individuals vary considerably in the amount and consistency of their ear wax. There are two types described, wet and dry, which are inherited. Dry wax is common in Asia, while wet wax is common in western Europe. Dry wax, also known as "rice-bran wax", contains by weight about 20% lipid (fat). Oddly enough, rice-bran wax is associated with a lower incidence of breast cancer (Hawke, 2002).
Wet wax consists of approximately 50% lipid (Burkhart et al, 2000). Wet wax can be either soft or hard, the hard wax being more likely to be impacted. While ear wax is generally simply felt to be a nuisance, in medieval times, ear wax was used as a component of pigment for illumination of manuscripts (Petrakis, 2000). Too little ear wax increases the risk of infection (Fairey et al, 1985). Too much wax also increases the incidence of infection and hearing loss. So, you want just enough.
While we are not aware of a study of this, some people (and some ears) are "wax producers", and others remain wax free without much maintenence.


圖片參考：http://www.tchain.com/otoneurology/images/Ear-Wax-Blockage-cd.jpg