Arsenic is a naturally occurring, odorless, tasteless element found in soil, bedrock and water.                                         

Because it is an element, arsenic persists in the environment and does not deteriorate. 


Types of arsenic

Two species of arsenic are typically found in drinking water: Arsenic 3 and Arsenic 5.
Arsenic 3 is very difficult to remove from water, and must first be converted to arsenic 5. Chlorine is the most readily available oxidant to convert arsenic 3 to arsenic 5. For an additional cost, the laboratory can determine the species of arsenic in your water.

Commercial uses for Arsenic

Arsenic is used to manufacture other metals, glass, electronic components and wood preservatives. It is an important component of insecticides and weed killers. Mining, smelting and wood processing can also contribute to local arsenic burdens.
Health effects associated with arsenic exposure
Health effects related to arsenic are dependent on several factors
  • Dose (amount/concentration of arsenic)
  • Duration (length of exposure)
  • Type of exposure (oral, dermal)
    • Arsenic can cross the placental barrier in pregnant women, placing the fetus at risk
Most health effects are due to chronic exposure to arsenic-contaminated drinking water, to include
  • Anemia
  • High blood pressure
  • Cardiovascular damage
  • Bronchitis
  • Impaired nerve functioning (“pins and needles” in hands and feet)
  • Skin pigmentationCancer risk (skin, liver, bladder and lungs)Increased risk of Type 2 diabetes
    • Keratosis or corns on the hands and feet

Drinking water regulations

In 2001 the United States Environmental Protection Agency lowered the allowable level for arsenic in drinking water from 50 parts per billion (PPB) to 10 PPB. For conversions between PPB, PPM and the often used µg/L and mg/L units, please click here.

How to test your well water

Oregon’s Revised Statute (ORS) 448.271 states that property owners are required to test well water used for drinking and other household purposes for arsenic, nitrate and total coliform bacteria when selling real estate that includes a domestic well. Test results must be reported within 90 days to the real estate buyer and Drinking Water Services after the seller receives the test result.
To test your water, contact an accredited laboratory that performs well water testing for private property owners.
For a list of accredited laboratories in:
Oregon: Call or visit the Oregon Environmental Laboratory Accreditation Program (ORELAP)