Arsenic rarely occurs free in nature. Many of the metallic sulfide ores contain arsenic and most metals combine with it to form arsenides. The poisonous action of arsenic was known as early as the middle ages. Common arsenic compound causing poison are arsenites. Nausea and vomiting may also follow.
Diarrhoea soon sets in with colicky pains.
Delirium, weak pulse, convulsions and general paralysis with death complete the picture of acute arsenical poisoning. Long term exposures lead to hyper keratposis conjunctivitis, hyperpigmentation, skin cancer and gangrene in limbs. It occurs from eating arsenic contaminated food and inhaling arsenic containing dyes. The main source of chronic poisoning now is the continued ingestion of vegetables and fruits sprayed with arsenic. In Bangladesh, the source of arsenic poisoning is the underground water.