Arsenic is a ubiquitous element with metalloid properties. Its chemistry is complex and there are many different compounds of both organic and inorganic arsenic. In nature, it is widely distributed in rocks, soil and sediments. In water, arsenic occurs in both inorganic and organic forms. The main organic arsenics, methylarsenic acid and dimethylarsenic. In air, particulate matters have been shown to contain both inorganic and organic arsenic compounds. Plants grown on soil, marine algae and seaweed usually also contain considerable amount of arsenic. In industries arsenic compounds are mainly used in agriculture and forestry. Much smaller amount is used in the glass and chemical industries as feet, additive and drugs. Arsenic can be a source of environmental pollution, near sites of coal burning and smelting of metals.