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Learn what you need to know about arsenic.

Also known as: Arsen, Arsenia

What is arsenic?

Arsenic is a naturally occurring mineral found in soil, bedrock, and water. In its pure form, arsenic is a silver-gray or white brittle metal. Arsenic has no odor and is almost tasteless. Arsenic and its compounds have a variety of commercial uses. Manufacturers use arsenic to make other metals, glass, electronic components, and wood preservatives. Drugs used to treat parasite diseases have contained arsenic.

Arsenic comes in two forms, inorganic and organic arsenic. Inorganic arsenic can be found in soil, bedrock, and water and is highly toxic to human health. Organic arsenic can be found in aquatic organisms, such as fish and shellfish, and is less toxic.

Where is arsenic found?

Arsenic occurs naturally in some Wisconsin drinking water supplies. When arsenic is present in the soil, it can enter ground and surface water nearby. The Department of Natural Resources (DNR) arsenic webpage and brochure have information on homeowners can find out if water is safe to drink and what to do if levels are high. The Wisconsin Groundwater Coordinating Council’s report on arsenic has information on occurrence and steps that the Council is taking to address arsenic groundwater issues in the state.

Arsenic can also be found in aquatic organisms who have been exposed to contaminated water. Production of arsenic in the United States was ceased in 1985, however products imported from China, Chile, and Peru may still contain arsenic.

Arsenic exposure

The most common source for arsenic exposure for the general public is through food. Marine fish and seafood contain naturally high amounts of arsenic. However, the arsenic in these foods is organic, the less toxic form of arsenic. Calcium supplements made from seashells may also contain high levels of arsenic. Other common foods which may contain arsenic include rice, rice cereals, mushrooms, and poultry.

Arsenic has been found in groundwater throughout Wisconsin and is the most prevalent in the northeastern part of the state, where it can enter private wells. Homes that are near waste sites where paint, pesticides or electronic components are disposed of may also have arsenic in the drinking water. It is recommended to test for arsenic in private wells every 5 years. For more information on understanding your laboratory well test results, go to Arsenic in Private Well Water (P-45012 - English, Spanish, Hmong) Arsenic in water is not easily absorbed through intact skin, nor does it evaporate into the air.

Burning of arsenic-containing materials such as treated lumber will put arsenic fumes into the air where it can be inhaled. Burning treated wood in a wood stove or fireplace may expose people to dangerous levels of arsenic. The most common source of arsenic exposure in an occupational setting is through inhalation of arsenic fumes or dust.

What regulations and guidelines area available to protect people from arsenic?

The Wisconsin Department of Natural Resources regulates the amount of arsenic that can be released by industries into the air and water.

There is no standard for the amount of arsenic allowed in the air of homes. We use a formula to convert workplace limits to home limits. Based on the formula, we recommend levels of arsenic in the air of homes be no higher than 0.004 parts per million (ppm).

Wisconsin drinking water standards for arsenic are set at 10 parts per billion (ppb), or 10 micrograms per liter (µg/L). If your arsenic level is more than 10 ppb, we suggest you stop using your water for drinking and food preparation. The following list provides a general guide for the average person.

Arsenic level below 10 parts per billion (ppb)*
This water is safe to drink and use for food preparation.

Arsenic level between 10 ppb and 100 ppb*
Do not
drink your water or use it to prepare foods that require a lot of water (e.g., infant formula, soups, Jell-O, rice, coffee, tea) if the arsenic level is above 10 ppb. Washing foods and dishes in the water is safe, and is not a significant source of exposure.

Arsenic level above 100 ppb
Only use your water for flushing toilets. Do not use your water for other household uses (showering/bathing, washing dishes/clothes, etc.).

*Because levels can change over time, annual testing is recommended.

Health effects

Everyone's reaction is different

A person's reaction to chemicals depends on several things, including individual health, heredity, previous exposure to chemicals including medicines, and personal habits such as smoking or drinking. It’s also important to consider the length of exposure to the chemical, the amount of chemical exposure, and whether the chemical was inhaled, touched, or eaten.

Exposure to arsenic can cause several effects:

  • Arsenic has been associated with certain types of skin cancer. Some studies also show a possible link with lung, bladder, liver, colon, and kidney cancers.
  • Very high exposure to arsenic can cause noticeable changes to skin and nails, such as yellowing of the fingernails or certain pattern of skin changes that resemble warts, called "hyperkeratosis".
  • Very high exposure to arsenic can also cause confusion, hallucinations, impaired memory, and rapid changes in mood.
  • Arsenic is harmful to the nervous system. Symptoms of arsenic exposure include tremors, headaches, and numbness.
  • Other effects may include blood vessel damage, high blood pressure, anemia, stomach upsets, diabetes, and poor circulation which may lead to gangrene.

Children could be impacted

Arsenic can cross the placenta into unborn babies and can be found in low levels in breast milk. Prenatal and early childhood exposures to arsenic can increase the risk of lung cancer and respiratory disease in later life. Arsenic exposure has also been associated with lower IQ scores in school-aged children and can affect learning. The current standard is intended to protect the developing fetus and young children from these effects.

Medical tests

Urine can be tested for arsenic up to a week after the exposure. The results of arsenic urine tests may be misleading if you have eaten seafood, marine fish or ocean-derived vitamin supplements in the past five days.

If a person suspects high arsenic exposure, tests that monitor the functioning of the liver and kidneys should be done. These tests can be done by a doctor on blood samples.

Seek medical advice if you have any symptoms that you think may be related to chemical exposure.

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Last revised February 14, 2023