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Arsenic occurs naturally in groundwater and is found in rocks, vegetables and the human body. It can enter drinking water supplies in communities where groundwater makes up a large part of the total water supply, like Tucson. Some people who drink water over many years could experience skin damage or problems with their circulatory system, and may have an increased risk of getting cancer.

The EPA recently lowered the amount of arsenic allowed in our nation’s drinking water from 0.050 milligrams per liter (mg/L) to 0.010 mg/L, effective January 2006. A milligram per liter is the same as 1 teaspoon in 1,320 gallons. Tucson Water will not have difficulty meeting the new standard because most of our wells currently contain arsenic below 0.010 mg/L except for two wells in our main distribution system which in 2003 had a level of 0.014 mg/L and 0.010 mg/L respectively. These wells will be closed or the water will be blended with other wells so that the arsenic is diluted to a safe level. One isolated water system is served solely by a single well where the arsenic level is greater than 0.010 mg/L. At this site Tucson Water and the American Water Works Research Foundation project have been evaluating the use of specialized treatment filters designed to remove arsenic from water and the
possibility of drilling a new well.


Arsenic water droplet

For more information:

EPA’s Safe Drinking Water Hotline

United States Environmental Protection Agency (USEPA) http://www.epa.gov/safewater/arsenic.html

Ajo, Ariz. Arsenic Information
(under construction!)


Arsenic Resources - explore this section to find more information available on the Internet on arsenic and how it could affect your health.

At the University of Arizona, Drs. Walter Klimecki and Jay Gandolfi both study how our genes play a role in our ability to metabolize the cancer causing agent Arsenic. Ultimately their research could produce a set of predictors that could help identify who might be more affected by arsenic exposure. Read the interview Dr. Klimecki below...


Where can I get more information?

The following agencies have information about arsenic exposure, testing and treatment.

  • Arizona Department of Environmental Quality, Drinking Water Section Phoenix  (602) 771-4648

  • Pima County Environmental Services Department 
    (520) 740-3340

  • Tucson Water Quality Management Division  
    (520) 791-5252

  • USEPA’s Safe Drinking Water Hotline 1-800-426-4791


What is Arsenic?

Arsenic (As) is an element found in the earth’s crust. It has no smell or taste but can be silver-gray or yellow in color. Arsenic is a solid and can dissolve in water. It also has two chemical forms, organic and inorganic. Organic arsenic is relatively non-toxic and occurs in ocean fish and seafood. Inorganic arsenic is toxic and can be found in water, bedrock, sand and gravel.

How can I be exposed to arsenic?

Most people are exposed to some amount of arsenic since it is a natural part of our environment. However, too much of it will result in harmful side effects. A person can be exposed to arsenic through:

  • Drinking Water
  • Food
  • Smoke from burning oil, gasoline, wood, coal, tobacco products
  • Air
  • Natural activities such as volcanoes, erosion of rock, forest fires
  • Dust from industry
  • Wood preservatives, paints, dyes, metals, medicines, soaps and semi-conductors
  • Mining and smelting
  • Agricultural activities

How does arsenic get into the drinking water supply?

  • Some communities, get their drinking water largely from groundwater. This is the water that supplies the wells and springs that bring water to your home or business.
  • Arsenic dissolves into the groundwater and is then drawn into the wells that provide your drinking water

How can I find out if my drinking water is safe to drink?

The only way to know if your drinking water contains arsenic is to have it tested.

If you are a customer of a community water system you can contact your local office to find out what the arsenic level is in your drinking water. The water is tested at least every three years.

If you have a private well you can take a water sample to a state certified laboratory. The best time to take a sample is during the time that reflects when you typically use water.

By Federal law public water systems must test the drinking water they deliver and provide an annual water quality report to their customers known as a Consumer Confidence Report (CCR). This CCR is a general overview of the water quality of that system and will show which regulated contaminants such as arsenic were found in the drinking water and in what quantities for the previous year.

How can arsenic affect my health?

There are several factors that will determine your health risk:

  • Dose: How much arsenic you are exposed to
  • Duration: How long you are exposed to arsenic
  • Type of arsenic: inorganic or organic
  • General health, what you eat, age and lifestyle

People might have health problems if they are exposed to high concentrations of arsenic over many years. The development of health problems depends on how arsenic got into their bodies and how much was absorbed.

  • Arsenic gets into human bodies easily by drinking water that has arsenic in it. It is difficult to take in arsenic from the air.
  • The way arsenic affects our bodies is not fully understood. Some health problems have been shown from drinking water that has large amounts of arsenic in it.
  • There may be some risk for cancer connected to drinking water with low amounts of arsenic in it. No one knows exactly what is a “safe” level of arsenic in drinking water.

Cancer Risk from Low / Moderate Level Exposure:

  • Skin Cancer
  • Internal cancers – bladder, prostate, lung

Symptoms of High Level Exposure:

  • Thick, rough skin on hands and feet
  • Unusual skin coloring – dark brown or white splotches
  • Numbness in the hands and feet
  • Circulatory disorders
  • Tremors
  • Stomach pain, nausea, diarrhea
  • Possibly diabetes – this effect has not been confirmed
  • Many of the same symptoms that can occur with high exposure to arsenic are also seen with common illnesses. It may be difficult for a doctor to recognize arsenic related health problems. You should talk to your doctor if you are concerned about health problems that may be related to arsenic in your drinking water. Your doctor will want to evaluate your health concerns and may want to check the level of arsenic in your body by analyzing a urine sample.
  • You should also consider testing your well water if you are not using your local drinking water company or community water supply.
  • In most cases it is safe to use water that contains arsenic for bathing, laundering, showering and washing dishes because arsenic does not easily get into your skin. It is not safe to use drinking water that has high levels of arsenic for drinking and cooking

How do I lower my exposure to arsenic in drinking water?

If the arsenic level is above 0.01 mg/L it is recommended to stop using your water for drinking and cooking. If the arsenic level is below 0.01 mg/L in your drinking water it is safe to drink.

  • Bottled water can serve as an alternative source of drinking water.
  • If you have a private well connecting to a community water supply. This may be the most cost-effective solution. Other options include modifying the well drilling a new well or utilizing a water treatment system.
  • Water treatment systems that use water softeners, carbon filters and sediment filters cannot adequately remove arsenic from drinking water.
  • A point-of-use treatment system that treats the faucet used for drinking and cooking can be used.
  • Another option is a point-of-entry treatment system that treats the drinking water for the entire household system.
  • It is recommended that any treatment system be certified by the NSF International, and be installed by a licensed plumber. You will need to follow the manufacturer’s instructions to make sure the treatment system operates correctly to continue removing arsenic effectively.

How do I interpret the water sample results?

On October 31, 2001 the USEPA lowered the level of arsenic in drinking water from 0.05 milligrams per liter (mg/L)* to 0.01 mg/L. Most community water systems must meet this new primary drinking water standard by January 26, 2006.

*One milligram per liter is a very small amount and is the same as 1 teaspoon in 1,320 gallons.

Spotlight Mechanisms of Environmental Chemical Toxicity

Dr. Walter Klimecki
Dr. A. Jay Gandolfi

Dr. Walt Klimecki is a Research Assistant Professor of Medicine at the Arizona Respiratory Center (College of Medicine).

Dr. A. Jay Gandolfi is a Professor of Pharmacology and Toxicology (College of Pharmacy). He is also the Director of the Super Fund Program, and the Assistant Dean of the College of Pharmacy.

Arsenic does not follow the book. It is an environmental toxicant, but often unrelated to industrial sources. It is a metal, but its metabolism involves organic modifications. It is an indisputable human carcinogen, but is largely negative in typical animal models of chemical carcinogenesis and its carcinogenic mechanism of action is a topic of great scientific debate. Oh, and by the way, arsenic is an excellent, anti-cancer pharmacological agent.

“Because of its mechanistic complexity that includes ambiguous results in animal models, any comprehensive effort to study arsenic toxicology must include human studies in exposed populations”, says SWEHSC researcher Walt Klimecki, DVM, Ph.D.

In an effort that was initiated by a SWEHSC Pilot Project award, Dr. Klimecki’s group has produced catalogs of all commonly occurring genetic polymorphisms of importance to Hispanic populations in the genes currently identified as potentially involved in human arsenic metabolism. Klimecki adds, “Because we know that different arsenic chemical species produced by human metabolism have dramatically differing toxic potency, we felt that studying the human genetics of arsenic metabolism was the logical place to start.”

The human polymorphism catalogs of three genes, GST-Omega, NP, and Cyt19, have produced exciting results that are, in turn, becoming the basis for further research. GST-Omega, for example, was sequenced in 24 human DNA samples from several indigenous American groups from Central and South America, as well as in 22 European ancestry samples.

The level of genetic diversity in the two populations was dramatically different. The indigenous American population was much less genetically diverse than the European population. Initial analysis of the resequencing data indicates that the genomic region that contains GST-Omega was subject to selective pressure that altered the distribution of genetic variation in some populations, a line of research that has sparked a collaboration with Matt Saunders, a graduate student in Michael Nachman’s laboratory in the U of A Ecology and Evolutionary Biology department.

Resequencing of Cyt19 revealed that a significant portion of the first exon is missing in many humans. Follow-up sequencing work in the chimpanzee produced a surprising finding, in contrast to the typically close DNA sequence homology between chimp and human; in Cyt19 the chimp has a very different first exon structure and sequence than the human.

“Because the arsenic literature suggests that the chimp is not capable of organically modifying arsenic, we have been sequencing the chimp for all the human arsenic-metabolizing genes, to look for potential inter-species DNA sequence differences that might explain the inter-species metabolism differences. The Cyt19, exon 1 data is an exciting lead that needs to be pursued in this context”, says Klimecki.

An additional arm of Dr. Klimecki’s work involves testing a subset of the discovered polymorphisms in these three candidate genes for association with phenotypes related to arsenic metabolism.

In a collaborative project with SWEHSC researcher Jay Gandolfi, a population of approximately 150 arsenic-exposed subjects that Gandolfi’s group has been studying was tested at 23 polymorphic DNA positions from the three genes. Gandolfi’s group has measured the urinary concentration of the major arsenic metabolites in these subjects.

By comparing the subjects’ DNA sequence against their profile of arsenic metabolites, the collaboration will look for evidence that particular genes and particular polymorphisms are important in arsenic metabolism in these populations. Currently underway, this work has the ultimate objective of translating these genetic studies into a set of predictors that could someday identify individuals who may be at particular risk from arsenic exposure.


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Southwest Environmental Health Sciences Center
University of Arizona College of Pharmacy, Room 244
PO Box 210207, Tucson, AZ, USA 85721-0207

What is Arsenic? | How can I be exposed to arsenic?| How does arsenic get into the drinking water supply? | How can arsenic affect my health? | How can I find out if my drinking water is safe to drink? | How do I interpret the water sample results? | How do I lower my exposure to arsenic in drinking water? | Where can I get more information? | Arsenic & Cancer Information by Dr. Clark Lantz | Dr. Walter Klimecki's interview |Arsenic Resources |Ajo, Ariz. Arsenic Information|

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Last update: September 18, 2008
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