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More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
The B-complex vitamins and vitamin C are not stored in the body and must be replaced each day.
Everyone has one nostril that is larger than the other.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Vaccines prevent between 2.5 and 4 million deaths every year.
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