Sebaceous gland Sebaceous gland Sebaceous glands are microscopic exocrine glands in the skin that secrete an oily or waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals. In humans, they occur in the greatest number on the face and scalp, but also on all parts of the skin except the palms of the hands and soles of the feet. The type of secretion of the sebaceous glands is referred to as holocrine. In the eyelids, meibomian glands, also called tarsal glands, are a type of sebaceous gland that secrete a special type of sebum into tears. Fordyce
Oily fish potential dangers of ingesting polychlorinated biphenyls and dioxins. It reiterated the 1994 guideline of two portions of fish per week including one portion of oily fish, but advised eating no more than four portions per week, and no more than two portions for people who are pregnant, may become pregnant or who are breastfeeding. The United States Environmental Protection Agency's (EPA) Exposure Reference Dose (RfI) for methylmercury (MeHg) is 0.1 micrograms per kg body weight per day. The corresponding limit of blood mercury is 5.8 micrograms per liter. The restrictions apply to certain oily fish – "marlin, swordfish, shark and,