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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Nearly 31 million adults in America have a total cholesterol level that is more than 240 mg per dL.
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.
Certain chemicals, after ingestion, can be converted by the body into cyanide. Most of these chemicals have been removed from the market, but some old nail polish remover, solvents, and plastics manufacturing solutions can contain these substances.
In 1844, Charles Goodyear obtained the first patent for a rubber condom.