The density of the metal greater than 4.5g/cm3 chemically known as heavy metals such as copper, lead, zinc, iron, cobalt, nickel, etc.. Certain heavy metals such as manganese, copper, zinc, iron and other trace elements needed by the activities of human life, but most of the heavy metals, such as mercury, lead, cadmium, etc., not required for life activities, and all heavy metals exceeds a certain concentration harmful. (Sand production line)
Because heavy metals can not be biodegradable, so basically into our body is not large is willing to come out.
Plant foods than animal foods for human beings is more secure, laws of ecology tells us that every increase of one trophic level, and difficult to break down pollutants will concentrate even several ten times. For example, if the concentration of certain contaminants in water is one hundred thousandth time to reach the algae will be concentrated to more than one ten thousandth; fish to eat algae for a living, it will continue to concentrate pollution; ones devour will be able to swallow a fish accumulate several months of pollutants; waterfowl eat small fish, the faster the rate of accumulation of pollution. pollutants from the environment, in animals with higher aggregation, and thus animal food contamination levels higher than the valley beans. (Zimbabwe impact crusher)
Heavy metals, it seems difficult to eat. In fact, these "toxic" heavy metals have begun to slowly invade our food.
Intake of heavy metals in three channels
First, the environmental pollution. Air pollution, water pollution and soil pollution, lead aquatic fruits and vegetables, heavy metals exceeded the most serious of which aquatic. Cigarettes even how excessive "heavy smoker" or continue to smoke, and the innocent people who inhale second-hand smoke; vehicle exhaust will allow many toxic heavy metals into the atmosphere, if the vegetable plot, Dasan at the roadside, vegetables and the tea inside the heavy metals will be exceeded. (Botswana mining equipment)
Contaminated food processing or during storage. Such as egg, as well as in food packaging, print quality, ink bags lead in "contaminated" food.
Daily necessities "eat" into heavy metal. Such as drinking water, lead, mercury pollution and the daily use of stainless steel tableware and ceramic tableware.