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Fungal nail infections account for up to 30% of all skin infections. They affect 5% of the general population—mostly people over the age of 70.
Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
Allergies play a major part in the health of children. The most prevalent childhood allergies are milk, egg, soy, wheat, peanuts, tree nuts, and seafood.
Though the United States has largely rejected the metric system, it is used for currency, as in 100 pennies = 1 dollar. Previously, the British currency system was used, with measurements such as 12 pence to the shilling, and 20 shillings to the pound.