What is Arsenic?
Arsenic is a naturally occurring metalloid element, commonly found in ground water. It is the 20th most abundant element in the earth’s crust. In drinking water, it is tasteless and odorless. Arsenic is widely used as a wood preservative and as a poison for killing weeds, rats, and insects. It is toxic to humans in fairly low doses.
Arsenic in Arizona
Arsenic is present in almost all of Arizona’s ground water supply. In our Northern Arizona territory, most waters test between 5 and 50 parts per billion (ppb), although many wells test between 50 and 200 ppb. On the high side, we have seen some wells in the Paulden area testing between 2000 and 3662 ppb and some wells in the Verde between 500 and 1000 ppb. Arsenic exists in two different forms in our water: arsenate (As5-) and arsenite (As3-). In general, most of our arsenic is the less toxic As5, but we have encountered a well where the As3 accounted for 2/3 of the total arsenic, so it is not safe to assume without actually testing. As3 is easily converted to As5 by by oxidation , so it is safe to say that, if you are on a chlorinated water supply, all the arsenic will be As5.
Arsenic and the EPA
For years the federal government has had a maximum contaminate level (MCL) of 50 ppb for arsenic in public water supplies. In the last few years, researchers have concluded that the health risks from arsenic are greater than originally thought. Federal studies recommended that the MCL for arsenic should be 3-5 ppb. Because the cost of achieving this level for all public water supplies would be exorbitant, a 10 ppb MCL was adopted. Cost superseded public health. The new MCL became effective in January 2006. The rule does not apply to individuals who have their own private well or water system. Private well owners must assume responsibility for themselves in deciding whether to have their water tested for arsenic, what level of risk they are willing to take, and what form of treatment, if any, they wish to undertake.
For water with <200 ppb, the major health concern is an increased risk of cancer (such as skin, bladder, lung, kidney, or liver). Other risk associations are diabetes, keratosis, and heart disease.
Toxicity from arsenic is cumulative, especially in the doses that typically occur in our drinking water supply. The primary risk is from water and food. Dosage and duration of exposure are important factors in weighing adverse health effects. In most cases, no one will suffer any adverse health effects from drinking one glass of water or even a hundred glasses of water.
The risk from showering and bathing is less clear. While some research has indicated some skin absorption of arsenic from showering and bathing, other studies dismiss any correlation at lower levels. A number of state health departments state that there is little or no risk with showering or bathing in water with under 500 ppb of arsenic. In our opinion, more research still needs to be conducted on the risks associated with skin exposure before anything definitive can really be stated.
The National Institute of Health postulated that over a lifetime of consuming drinking water with a 50 ppb arsenic level, one additional death per hundred people could be expected. At 100 ppb, two additional deaths could be expected. Some studies predict that even at the new MCL of 10 ppb, that out of 1000 people, several people might get cancer. The National Research Council in a report for the National Academies predicted an additional four cancer deaths per 10,000 at even the low 3 ppb level. At doses over 200 ppb, more acute health effects may appear and in a shorter period of time. Many health effects resulting from low dose arsenic poisoning are seen with other common illnesses and are difficult to pinpoint to arsenic exposure. As a result, the risk studies cited above are out of necessity mathematical extrapolations taken from the best available information at the time, rather than actual data driven conclusions.
How much arsenic is too much?
The EPA has establshed an MCL of 10 ppb. The Arizona Department of Health warns of increase risk between 11 and 200 ppb and not using water above this at all for drinking, cooking brushing your teeth. The State of Massachusetts recommends that consumers stop using water over 10 ppb for drinking and either use another source or get water treatment. At over 200 ppb, they advise immediately stop using the water. Some states have decided to set their own MCL for arsenic at lower than 10 ppb. For example, New Jersey has set their MCL at 5 ppb. Many experts say that there is no safe level of the toxin. The government has decided the MCL for which it is willing to mandate and fund. You, as a private citizen, must decide what level of risk you want in your drinking water and establish your own MCL.
Arsenic Reduction for the Home
We offer several options for arsenic reduction. Because the threat from arsenic is primarily from drinking water, for most people in the under 50 ppb range, it probably makes most sense to treat only the water used for drinking and cooking. For most of those, a good reverse osmosis system is probably the best choice. People with higher levels of arsenic or those desiring more protection may wish to consider “whole house” arsenic treatment. Northern Arizona Quality Water offers multiple technologies from which to choose, including adsorption medias, whole house reverse osmosis, ion exchange, and different coagulation/filtration systems. Small changes in water chemistry can have dramatic effects on removal outcomes. Consequently, it is necessary to perform more extensive water testing than just a total arsenic test in order to determine the best and most cost effective arsenic reduction system for any situation.
Reverse Osmosis for Arsenic Reduction
For most people, a point of use reverse osmosis system is the most practical solution. We strongly recommend looking at only those systems that have been certified for arsenic reduction by NSF or WQA under their standard 58. We also strongly recommend asking for and comparing the NSF certified performance data sheets for average and minimum reduction. The Kinetico K5 Drinking Water Station has been certified to reduce the As5 an average of 99.3%. These reduction numbers are very strong. Small percentage differences in performance can be important in overall desired arsenic levels. Also, we can’t stress enough the importance of dealing with a reputable, licensed contractor for your water improvement needs.