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Thyroid conditions may make getting pregnant impossible.
There are 20 feet of blood vessels in each square inch of human skin.
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
Asthma is the most common chronic childhood disease in the world. Most children who develop asthma have symptoms before they are 5 years old.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.
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