Arsenic is an element that is naturally occurring and found in a number of sources. It can come in both organic and inorganic forms with the inorganic form being toxic and the organic nontoxic. Inorganic arsenic is present in rocks and soil. It can find its way into drinking water sources when wells are drawn from groundwater that flows through bedrock that contains arsenic. It may be present in soil either occurring naturally or as a result of the soil being treated with arsenic-containing pesticides or fertilizers.

Long-term exposure to arsenic in populations where the water and food sources are very high in arsenic has been associated with cancers of the skin, lung, and bladder. It can contribute to skin changes, cardiovascular diseases, and diabetes. In the US, exposure levels to arsenic through water and food sources are much lower than in other parts of the world, but some studies have found that there may be health effects in certain populations at lower levels.  Read more about what the latest research is finding about Arsenic in food and water.