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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.
Liver spots have nothing whatsoever to do with the liver. They are a type of freckles commonly seen in older adults who have been out in the sun without sufficient sunscreen.
Before a vaccine is licensed in the USA, the Food and Drug Administration (FDA) reviews it for safety and effectiveness. The CDC then reviews all studies again, as well as the American Academy of Pediatrics and the American Academy of Family Physicians. Every lot of vaccine is tested before administration to the public, and the FDA regularly inspects vaccine manufacturers' facilities.
A headache when you wake up in the morning is indicative of sinusitis. Other symptoms of sinusitis can include fever, weakness, tiredness, a cough that may be more severe at night, and a runny nose or nasal congestion.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).