Physiology, pathophysiology, and anthropology/epidemiology of human earcanal secretions

Two types of glands are found in the outer third of the human earcanal: sebaceous glands that produce sebum and modified apocrine glands that produce apocrine sweat. Together, these substances make up cerumen, which serves to clean, lubricate, and, to some extent, protect the earcanal from bacteria and fungus. Excessive/impacted cerumen can cause tinnitus, vertigo, itching, pain, external otitis, and hearing loss. Two populations are known to have a high incidence of excessive/impacted cerumen: individuals with mental retardation and the elderly. Anthropologists have used cerumen type to tract human migratory patterns and epidemiologists have related cerumen type to breast cancer.