Why Are We Concerned About Arsenic?

Exposure to arsenic in drinking water represents a significant health problem for people around the world. In 1997, the World Health Organization recommended that arsenic in drinking water be recognized as a major public health issue that should be addressed on an emergency basis. For humans, exposure to arsenic has been linked to increased risk of lung disease, heart disease, diabetes, cancer and reproductive disorders. However, most studies linking arsenic with human disease have involved people exposed to very high levels – in the workplace, for example, or in parts of Taiwan, Pakistan and other areas of the world where levels of arsenic in drinking water are unusually elevated. In Bangladesh and India, an estimated 200 million people have been exposed to well water with arsenic from natural sources deep within the ground.

During the 1950s, U.S. cotton-growers spread a pesticide that contained arsenic to fight the boll weevil. Although it was an effective pest control, low levels of arsenic remain in the soil of the fields where it was applied because arsenic does not break down in the environment, and can enter water sources from rainfall runoff. Certain food plants — particularly rice —have the ability to draw in arsenic from the soil without harming themselves. These “hyperaccumulators” present health risks to humans who eat them on a regular basis. Recent studies suggest that food may be as important as water as a source of arsenic.

In 2001, EPA lowered the public drinking water standard for arsenic from 50 to 10 parts per billion (ppb). Soils and well water in New Hampshire have been found to contain levels of arsenic that are substantially higher than levels found in other regions of the United States.

USGS MapCurrent estimates indicate that about 46 percent of New Hampshire’s 1.3 million people drink water from private wells, which have no state or federal safety requirements for arsenic. In some parts of the state, about one in five private wells contain high levels of arsenic from naturally-occurring sources in bedrock. The USGS map to the right shows locations of bedrock aquifer wells and concentrations of arsenic in water. Larger circles indicate higher concentrations. Studies have associated long-term, low-dose ingestion of arsenic with cancers of the skin, bladder, and lung, and other chronic health issues. As a result, New Hampshire has become the focus of geological, environmental and human health research studies. Other states with unusually high arsenic levels include Maine, Michigan, California, New Mexico, Arizona, Colorado and Nevada.

By conducting studies on the ways in which arsenic affects human health at the cellular level, and by determining the effects of very low levels of arsenic (less than 10 parts per billion), our researchers are increasing the body of knowledge on the effects of arsenic exposures at levels found commonly in the United States. Learning about metals in the environment and their resulting impacts to people through water and food pathways will provide answers to questions that are important in guiding public policy on setting acceptable levels of exposure.

Our website, Arsenic and You was launched in 2017 to help people learn if they are exposed to arsenic, and provides simple steps to reduce how much arsenic they may be getting into their bodies through water, food, smoking and other sources. Access it on your phone or tablet at