Fact Sheet - Arsenic

Estimated Population At Risk At Identified Sites: 3.7 Million People*

Estimated Global Impact: 5 to 9 Million People*

What Is Arsenic?

Arsenic is a naturally occurring element that has properties of both a metal and a nonmetal. In its elemental state, arsenic is a solid grey material; however, arsenic is often found in the environment combined with other elements. These arsenic compounds are generally white or colorless powders that have no smell or taste, making them difficult to detect in food, water, or air.

What Is Arsenic Used For?

Today, arsenic is used in lead batteries, lead shot, and bullets as an alloying agent, among other uses. Historically, arsenic was used to pressure-treat wood, and was commonly found in pesticides, herbicides, and insecticides. Arsenic is also used in some medicines, although this use has declined as our knowledge of the element’s harmful effects has increased.

How Is Arsenic Released Into The Environment?

Arsenic is often found in rocks that contain other valuable metals, such as copper and lead. When smelters heat this ore to retrieve the other metals, the arsenic is often released into the air as dust. Arsenic is also found in coal, and can be released through coal-fired power plants or incinerators that burn arsenic-containing products.

How Does Arsenic Reach Humans?

Once arsenic is released into the environment, it attaches to other particles and can easily be spread as wind-blown dust. Once in the air, arsenic can stay airborne for many days and travel great distances. Arsenic can also dissolve in water, and thus can easily contaminate lakes, rivers, and groundwater resources. Drinking arsenic-contaminated water is a serious health risk to humans. Groundwater contamination is a particularly serious problem in India, Nepal, and Bangladesh, where naturally occurring arsenic contaminates wells used by millions of people. Arsenic’s ranking in the list of the six top toxic threats is largely due to the number of people affected by naturally occurring arsenic contamination of groundwater in South Asia.

What Health Risks Can Arsenic Cause?

Arsenic has long been recognized as a poison, and while low doses of arsenic can cause decreased production of red and white blood cells, large doses can cause death. One common characteristic of arsenic poisoning is visible changes to the skin. People exposed to arsenic often have patches of dark skin, “corns,” and “warts.” Arsenic is also a human carcinogen, and exposure can result in cancer of the liver, bladder, lungs, and skin.

*Population estimates are preliminary and based on an ongoing global assessment of polluted sites.