(As, latin Arsenium)

Despite the reputation as a dangerous poison (as more than 1,000 years ago was considered the "king of poisons"), arsenic is the trace element with relatively low toxicity compared to other metals. In fact arsenic in small amounts, may be essential for the functioning of human. In experimental animal it was also proved to be essential, although added in amounts much larger than in humans.

The human body has about 10-20 milligrams of arsenic.