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.
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.
What are the properties of arsenic?
"Arsenic is a metalloid widely distributed in the earth’s crust and present at an average concentration of 2 mg/kg. Arsenic can exist in four valency states: –3, 0, +3 and +5. Under reducing conditions, arsenite (As (III)) is the dominant form; arsenate (As (V)) is generally the stable form in oxygenated environments. Elemental arsenic is not soluble in water. Arsenic salts exhibit a wide range of solubilities depending on pH and the ionic environment.
Arsenic and its compounds occur in crystalline, powder, amorphous or vitreous forms. They usually occur in trace quantities in all rock, soil, water and air. However, concentrations may be higher in certain areas as a result of weathering and anthropogenic activities including metal mining and smelting, fossil fuel combustion and pesticide use.
There are many arsenic compounds of environmental importance. Inorganic compounds include the trivalent arsenic trioxide, arsenic trichloride, arsenic trisulphide and sodium arsenite. Pentavalent ones include arsenic pentoxide, arsenic acid and sodium arsenate. Representative organic compounds are monomethyl-, dimethyl- and trimethylarsine, and arsenobetaine".
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:
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
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 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:
Smoke from burning oil, gasoline, wood, coal, tobacco products
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
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 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.