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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.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
The most dangerous mercury compound, dimethyl mercury, is so toxic that even a few microliters spilled on the skin can cause death. Mercury has been shown to accumulate in higher amounts in the following types of fish than other types: swordfish, shark, mackerel, tilefish, crab, and tuna.
Though the United States has largely rejected the metric system, it is used for currency, as in 100 pennies = 1 dollar. Previously, the British currency system was used, with measurements such as 12 pence to the shilling, and 20 shillings to the pound.
People with high total cholesterol have about two times the risk for heart disease as people with ideal levels.