Arsenic Fact Sheet
Reference: NSF/ANSI Standards 53 and 58 - 2002
Arsenic (As), a contaminant found naturally occurring in ground waters and generally occurs in two forms (valences or oxidation states): trivalent arsenic (also known as As(III), As(+3), or arsenite) and pentavalent arsenic (also known as As(V), As(+5), or arsenate). In ground water, arsenic may exist as a combination of both, or solely as pentavalent arsenic, or trivalent arsenic. Trivalent arsenic is considered more harmful than pentavalent arsenic, although both forms of arsenic are potentially harmful to human health.
Information about arsenic toxicity can be found at U.S. Environmental Protection Agency website.
The presence of an effective oxidant such as free chlorine converts trivalent arsenic to pentavalent arsenic. Treatment with chloramine (combined chlorine) is not sufficient to ensure complete conversion of trivalent arsenic to pentavalent arsenic. Arsenic in water containing detectable free chlorine (or treated with another effective oxidant) will be in the pentavalent arsenic form (1). Trivalent arsenic is generally more difficult to remove from drinking water than pentavalent arsenic.
Consumers should contact their public water utility to verify that free chlorine treatment chemicals are being used. Waters that do not have detectable free chlorine residuals and private water supplies should be analyzed to determine the type(s) of arsenic present and the potential need for oxidation of trivalent arsenic to pentavalent arsenic.
Arsenic generally does not impart taste, smell, or color to water, detected only by a chemical analytical test. Public water utilities are required to monitor their treated water for total arsenic (pentavalent arsenic plus trivalent arsenic) making test results available. Consumers with private water sources should have their water tested by a certified laboratory for (speciate) the two forms of arsenic present. Local environmental protection agencies and health departments can provide a list of certified laboratories.
Water treatment systems are tested under laboratory conditions and found to reduce either 0.30 mg/L or 0.050 mg/L (refer to the product listing for influent tested levels) in the test water to less than 0.010 mg/L, but may vary dependent on the specific water quality conditions at the consumer's installation. The treated water should be tested regularly to assure that the system is functioning properly and to verify that arsenic reduction is being achieved.
The pentavalent arsenic removal component of this system must be maintained and replaced periodically. Replacement components can be purchased from a retailer or distributor or directly from the manufacturer. Refer to the installation and operation manual to obtain replacement frequency and ordering information.
(1) - Source: Laboratory Study on the Oxidation of Arsenic III to Arsenic V, EPA/600/R-01/021, March 2001
The MultiPure Aquaperform MP880 Models are designed to remove only pentavalent arsenic and will not convert trivalent arsenic to pentavalent arsenic. The Aquaperform may remove some trivalent arsenic but has not been evaluated for this ability. Under lab conditions, the system reduced 0.050 mg/L (ppm) pentavalent arsenic to 0.010 mg/L (ppm) (the U.S. EPA standard for drinking water) or less, as defined in ANSI/NSF Standard 53.
Q: Several months ago, my feet and the front of my legs became numb. My doctor sent me to a neurologist, who put me through some tests: blood work, chest X-ray, mammogram, an MRI, and electric needles along my feet, legs and arms. He found I had insignificant carpal tunnel, but everything else came back negative, except that I had arsenic poisoning. Can you tell me how long I could have had it in my system and how it might have gotten there? Meanwhile, my feet and legs are still numb. Where should I go next, or whom should I see?
A: One of the most common causes of chronic arsenic poisoning is inhaling dust and chemical debris that are released into the atmosphere by coal-burning electric-generation plants. Arsenic may occasionally be present in contaminated drinking water. Further, arsenic is found in many pesticides and herbicides. Your local state health department should be able to identify the source of your poisoning, which is treated by chelation with penicillamine. Your doctor can assist you in solving this challenging problem.
Source: Dr. Peter Gott