Water poisoning is caused by too much consumption of water during a short period of time. Water in and of itself is not poisonous by any means, but rapid intake of a large quantity of water can break the careful balance of sodium(钠)in the body fluids(体液). This contributes to a swelling of the cells, often in the central nervous system, including the brain.
When the cells can no longer bear the pressure, they can begin to die. This is indicated in serious forms of water poisoning. Symptoms of this condition include vomiting, headache and unresponsiveness. When the sodium in the blood falls to dangerous levels, brain damage and possibly death may occur.
What is a fatal(致命的)amount of water can vary from person to person, depending on one's state of health, his or her physical activity at the time, the temperature and the amount of time in which the person consumes the water. For some, a one-time consumption of three liters can prove deadly. Although the person consuming the water may lose a lot of fluid during heavy labor or exercise, the electrolytes(电解质)are not replaced fast enough to avoid water poisoning.
Those particularly at risk for water poisoning are athletes engaged in long distance running like a marathon. Due to the need to replace large quantities of lost fluid, runners must drink a lot of water. This can lead to poisoning, so runners must replace their fluids with sports drinks that have added electrolytes. Other factors that contribute to water poisoning include activities that stimulate heavy sweating. The person working under extreme heat or intense humidity(湿气)must be careful when consuming water in order to maintain electrolyte balance. Mental diseases can also lead to water poisoning. Psychogenic polydipsia is a condition in which the affected person feels a need to drink a lot of water for unknown reasons.
