Introduction

Arsenic

Arsenic is a naturally occurring chemical element that is widely distributed in the Earth’s crust. Arsenic levels in the environment can vary by locality, and it is found in water, air, and soil.

Arsenic in drinking water is a widespread concern. But, arsenic levels tend to be higher in groundwater sources, such as wells, than from surface sources, such as lakes or reservoirs.

Water, air, and soil contamination from mining and fracking, coal-fired power plants, arsenic-treated lumber, and arsenic-containing pesticides also contributes to increased levels of arsenic in certain locations.

There are two general forms of arsenic:

• Organic - In this case, the term simply means the arsenic compound contains carbon. There is no relation to organic farming practices.
• Inorganic - Research indicates that toxicity levels are higher and associated health effects are more severe with inorganic arsenic.

Scientists, pediatricians, and public health professionals are concerned about subtle and long-range health effects of low-level exposures to arsenic in people. There is particular concern for infants and children exposed to arsenic in water and some foods during their development.

What are sources of arsenic?

The most common source of inorganic arsenic is contaminated drinking water. Arsenic in drinking water is a problem in many countries around the world, including Bangladesh, Chile, China, Vietnam, Taiwan, India, and the United States. ¹ The U.S. Geological Survey studies sources of arsenic to help local health officials better manage water resources.

Arsenic may be found in foods, including rice and some fish, due to its presence in soil or water. As a naturally occurring element, it is not possible to remove arsenic entirely from the environment or food supply. The U.S. Food and Drug Administration monitors and regulates levels of arsenic in certain foods. FDA prioritizes monitoring inorganic arsenic levels in foods, such as infant rice cereal, more likely to be eaten by young children.

Arsenic may be a component of air pollution. People could also touch dust containing arsenic, but this is not a significant way to be exposed.

How much arsenic can be in drinking water?

The maximum level of inorganic arsenic permitted in U.S. drinking water is 10 parts per billion (ppb). This standard was set by the U.S. Environmental Protection Agency (EPA). Some states, such as New Jersey, have more stringent drinking water standards for arsenic than 10 ppb. There are no arsenic water standards for private wells.

Because arsenic is tasteless, colorless, and odorless, testing is needed for detection. Approximately 7% of wells in the U.S. are thought to have arsenic levels above the current EPA standard of 10 ppb. ²

Arsenic levels in the U.S. tend to be higher in rural communities in the Southwest, Midwest, and Northeast. The levels of arsenic in countries like Bangladesh have been measured at over 3,000 ppb.

How can I find out whether there is arsenic in my drinking water?

If your home is not on a public water system, you can have your water tested for arsenic. Your state certification officer should be able to provide a list of laboratories in your area that will perform tests on drinking water for a fee.

How do I remove arsenic from my drinking water?

Do not try to remove arsenic by boiling it. Additionally, chlorine bleach disinfection will not remove arsenic. You may wish to consider water treatment methods such as reverse osmosis, ultra-filtration, or ion exchange. Contact your local health department for recommended procedures.

How does arsenic affect people?

Arsenic affects a broad range of organs and systems including:

• Skin
• Nervous system
• Respiratory system
• Cardiovascular system
• Liver, kidney, bladder and prostate
• Immune system
• Endocrine system
• Developmental processes

What Is NIEHS Doing?

Because of its significance as a global public health problem, studies of arsenic, arsenic metabolism, and the health effects associated with arsenic exposure are a priority for the National Institute of Environmental Health Sciences (NIEHS), the National Toxicology Program (NTP), and several other organizations involved in research, regulation, and health care.

NIEHS, particularly the Superfund Research Program through its grantees, and NTP conduct arsenic research, which includes:

Fundamental arsenic research

Researchers have learned that both short-term and long-term exposure to arsenic can cause health problems, but they are just beginning to understand how arsenic works in the body — what is referred to as its modes of action.

For example, researchers are finding that arsenic, even at low levels, can interfere with the body’s endocrine system. The endocrine system is what keeps our bodies in balance, maintaining homeostasis and guiding growth and development. In several cell culture and animal models, arsenic has been found to act as an endocrine disruptor, which may underlie many of its health effects. ³ Other mechanisms are also likely contributors to arsenic’s health effects.

Arsenic and cancer

Arsenic is a known human carcinogen associated with skin, lung, bladder, kidney, and liver cancer. ⁴ A new study from the NTP Laboratory that replicates how humans are exposed to arsenic through their whole lifetime found that mice exposed to low concentrations of arsenic in drinking water developed lung cancer. The concentrations in the drinking water given to the mice were similar to what humans, who use water from contaminated wells, might consume. ⁵

Early-life exposures to arsenic and development

Not only is arsenic a known human carcinogen, but it can predispose children to other health problems later in life.

Researchers supported by the NIEHS Superfund Research Program at the University of California, Berkeley, found increased incidence of lung and bladder cancer in adults exposed to arsenic early in life, even up to 40 years after high exposures ceased.

These findings provide rare human evidence that an early-life environmental exposure can be associated with a high risk of cancer as an adult. ⁶

Arsenic and diabetes

Several studies, including a review of the literature by NTP, have suggested an association between low-to-moderate levels of arsenic and metabolic diseases, such as diabetes. ⁷

Translational research on arsenic

At least 30 million people in Bangladesh are exposed to arsenic in their drinking water. Researchers have found that arsenic education, coupled with water testing programs, can increase knowledge in the population, and result in reduced arsenic exposures, when safe drinking water sources are made available. ⁸

Researchers also found that folic acid supplements can dramatically lower blood arsenic levels in individuals chronically exposed to arsenic-contaminated drinking water. Just 400 micrograms a day of folic acid, the U.S. Recommended Dietary Allowance, reduced total blood arsenic levels in a Bangladesh study population by 14 percent. ⁹

Further Reading

Stories from the Environmental Factor (NIEHS newsletter)

• Webinar Recognizes Early-career Scientists' Research on Lead, Arsenic (March 2022)
• Educational Tool Highlights COVID-19 and Arsenic Research (March 2022)
• E-cigarettes Expose Users to Toxic Metals Such As Arsenic, Lead (February 2022)
• Arsenic, Uranium Mix May Increase Diabetes Risk in American Indians (November 2021)
• Arsenic, Fluorescent Mice, and PFAS Among Topics at Tox Conference (October 2020)
• Linking Exposures to Later-life Disease — Webinars Draw Hundreds (July 2020)
• COVID-19 Shines Light on Navajo Water Contamination (June 2020)
• Bangladeshi Officials Learn How NIEHS Research Helps Their Country (April 2020)

Additional Resources

• Arsenic — Occupational Safety and Health Administration Safety and Health Topic
• Arsenic - Toxic Substances Portal — Agency for Toxic Substances and Disease Registry
• Arsenic Literature Collection — This curated collection of scientific articles, published in the journal Environmental Health Perspectives, reports on the prevalence of arsenic exposure, its toxicity, the complex mechanisms involved, and the implications for society and communities.
• Guidance for Industry: Action Level for Inorganic Arsenic in Rice Cereals for Infants — The Food and Drug Administration suggests how manufacturers of infant rice cereals can help protect public health by reducing inorganic arsenic, achievable by using good manufacturing practices.
• Indigenous Health Collection — Environmental Health Perspectives (EHP) present a collection of papers focusing on indigenous peoples who overall experience a disproportionate burden of several chronic diseases, compared with other racial and ethnic groups.

Related Health Topics

• Endocrine Disruptors
• Safe Water and Your Health
• Toxicology