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Occupational & Environmental Epidemiology


Arsenic is a naturally occurring element that is found throughout the environment. Pure inorganic arsenic is a gray-colored metal, but inorganic arsenic is usually found combined with other elements such as oxygen, chlorine and sulfur. Arsenic in animals and plants combines with carbon and hydrogen to form organic arsenic compounds. Arsenic is toxic, and inorganic arsenic is known to cause cancer.

Inorganic arsenic is released into the air by volcanoes, into air and water by the weathering of natural arsenic-containing minerals and ores, and into the environment by commercial or industrial processes such as smelting and some types of manufacturing. Organic arsenic compounds are used as pesticides, primarily on cotton fields and orchards, where they can contaminate soil and water.

Sources of Exposure

For most people, food or water is the major source of exposure to arsenic, with lower amounts coming from drinking water (including well water) and air. Some homeopathic and folk remedies also contain arsenic. Elevated levels of inorganic arsenic may be present in soil, either from natural mineral deposits or contamination from human activities, which may lead to skin or oral exposure. Arsenic has been identified at some hazardous waste sites in North Carolina.

Another source of exposure is wood that has been pressure-treated with chromated copper arsenate, or CCA, to preserve it for outdoor use in decks, boardwalks, picnic tables and wooden play structures. Arsenic leaches from the wood over time and is easily transferred to people's hands and skin, and thereby into their mouths, especially in the case of children. Burning treated wood also releases arsenic. Although the use of CCA-treated wood has not been allowed since 2003 for such residential applications, people will be exposed to the existing structures for years to come.

Arsenic in North Carolina private well water from 1998 to 2010, for the most part, averaged less than the EPA maximum contaminant level of 10 µg/L. (See Facts & Figures: Arsenic in Private Well Water 1998-2010.) Because concentrations of pollutants and groundwater flow are subject to change, private well owners should regularly test their well water for heavy metals (includingarsenic) and other contaminants. See N.C. DPH water testing recommendations for North Carolina private well owners.

  • Protect Yourself from Arsenic in Well Water (English / Spanish) (PDF)

Health Effects

Arsenic can cause health problems if it is absorbed through the skin or mucous membranes, ingested or inhaled. Health effects vary based on the type of compound and the amount of exposure. They can range from skin and lung irritation to gastrointestinal illness, nervous system involvement, cancer and death.

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