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Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Bacteria have been found alive in a lake buried one half mile under ice in Antarctica.
In the United States, an estimated 50 million unnecessary antibiotics are prescribed for viral respiratory infections.