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Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
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.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
There are 20 feet of blood vessels in each square inch of human skin.