Arsenic occurs naturally in the environment, and is generally combined with oxygen, chlorine and sulphur to form inorganic arsenic compounds. Organic arsenic compounds are formed when the element combines with carbon and hydrogen.

Arsenic and compounds are used in wood preservatives and pesticides. Arsenic compounds are used for hardening copper, lead and other alloys, most arsenic compounds are manufactured using arsenic trioxide as a raw material and are also used for treating sulphide ores, pesticides and plant and veterinary chemicals.