Arsenic Overview

Arsenic, the 20th most abundant element in the earth’s crust, occurs naturally in soil and minerals and therefore it may enter the water from natural deposits, runoff or leaching. Arsenic is associated with ores mined for metals, such as copper, and may enter the environment during the mining and smelting of these ores.

Arsenic cannot be destroyed in the environment. It can only change its form, or become attached or separated, from particles

Concentration of arsenic in soil varies widely across the United States depending on the source rock type; generally it ranges from 1 to 40 milligrams per kilogram, with an average of 5 milligrams per kilogram. However soils in the vicinity of arsenic-rich geological deposits, as found in Arizona, may contain much higher levels of arsenic. The concentration of arsenic in natural surface and groundwater is generally about 1 ppb but may exceed 1,000 ppb in areas where arsenic levels in soil are high. Groundwater is far more likely to contain high levels of arsenic than surface water. Surveys of U.S. drinking water indicate that about 80% of water supplies have less than 2 ppb of arsenic, but 2% of supplies exceed 20 ppb of arsenic.

Arsenic can be ingested in either the organic or inorganic form. Exposure to arsenic in a large concentration over a very short period of time (acute health impact) to inorganic arsenic can result in gastrointestinal irritation, low blood pressure, and cardiovascular attacks and in extreme cases death. Ingestion of lower concentrations of arsenic over a longer period of time from drinking water is typically classified as a chronic exposure. Symptoms of chronic arsenic exposure include changes in skin pigmentation, skin ulcerations and can cause stomach ache, nausea, vomiting, and diarrhea. Other effects from ingesting arsenic include decreased production of red and white blood cells which may cause fatigue, abnormal heart rhythm, blood-vessel damage resulting in bruising, and impaired nerve function. Arsenic ingestion has also been linked to skin, liver, bladder, kidneys, prostate, lung and other forms of cancer.

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