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Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
An identified risk factor for osteoporosis is the intake of excessive amounts of vitamin A. Dietary intake of approximately double the recommended daily amount of vitamin A, by women, has been shown to reduce bone mineral density and increase the chances for hip fractures compared with women who consumed the recommended daily amount (or less) of vitamin A.
There are approximately 3 million unintended pregnancies in the United States each year.
The ratio of hydrogen atoms to oxygen in water (H2O) is 2:1.
The lipid bilayer is made of phospholipids. They are arranged in a double layer because one of their ends is attracted to water while the other is repelled by water.