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A is for Arsenic                                         
By David F. Walling

The EPA is proposing to reduce the public health risks from arsenic in the nations drinking water by changing the current arsenic standard from 50 parts per billion (ppb) to a much lower level of 5 ppb.

A March 1999, report by the National Academy of Sciences concluded that the current standard does not achieve EPA's goal of protecting public health and should be lowered as soon as possible. Under the Safe Drinking Water Act Amendments of 1996, EPA is required to publicize a final rule by January 1, 2001.

Long term exposure to low concentrations of arsenic in drinking water can lead to skin, bladder, lung, and prostate cancer. Non-cancer effects of ingesting arsenic at low levels include cardiovascular disease, diabetes, and anemia, as well as reproductive and developmental, immunological, and neurological effects.

Short-term exposure to high doses of arsenic can cause other adverse health effects, but such exposures do not occur from U.S. public water supplies at the current standard of 50 ppb.
EPA set the current standard of 50 ppb in 1975, based on a Public Health Service standard originally established in 1942.

People at greatest risk from long-term exposure are children, pregnant and lactating women, and people with poor nutritional status and individuals with pre- existing diseases that affect specific organs.

For community water systems that require corrective action to meet a standard of 5 ppb, the EPA estimates that annual household costs will average $28 for Americans served by large systems and $85 for those served by small systems (those serving fewer than 10,000 people). Over 98 percent of the cost to a water utility will come from adding treatment equipment, chemicals, and management of the new treatment.

Since 1996, EPA's state revolving fund program has made available $3.6 billion to assist drinking water systems with projects to improve their infrastructure. EPA has funded over 1000 loans for projects around the country.

Arsenic occurs naturally in rocks and soil, water, air, and plants. It can be further released into the environment through natural activities such as volcanic action, erosion of rocks, and forest fires, or through human actions. Approximately 90 percent of industrial arsenic in the U.S. is used as a wood preservative, but arsenic is also used in paints, dyes, metals, drugs, soaps, and semi-conductors. Burning fossil fuels, paper production, cement manufacturing, and mining can also release arsenic into the environment.

While many community water systems may have no detected arsenic in their drinking water above 5 ppb, there may be "hot spots" with higher than the predicted levels of arsenic for that area. Water systems in western states that depend on underground sources of drinking water have naturally occurring levels of arsenic at levels greater than 10 ppb. Parts of the Midwest and New England have some systems whose current arsenic levels range from 2-10 ppb.

The EPA is also proposing a public health goal of zero for arsenic. The health goal is the level below which no known or anticipated health effects would occur. EPA sets public health goals at zero for all known carcinogens for which there is no dose considered safe.

EPA has issued drinking water standards, or Maximum Contaminant Levels (MCLs) for more than 80 contaminants. The standards limit the amount of each substance allowed to be present in drinking water. Currently, the nations approximately 55,000 Community Water Systems (CWSs) must test for these contaminants that may or may not be present in the water. In 1996, 4,151 systems, or 7 percent, reported one or more MCL violations, and 681 systems (less than 2 percent) reported violations of treatment technique standards.

A process called risk assessment is used to set drinking water quality standards. When assessing the cancer and non-cancer risks from exposure to a chemical in drinking water, the first step is to measure how much of the chemical could be in the water. Next, scientists estimate how much of the chemical the average person is likely to drink. This amount is called the exposure

In developing drinking water standards, EPA assumes that the average adult drinks 2 liters of water each day throughout a 70-year life span.

Risks are estimated separately for cancer and non-cancer effects. For cancer effects, a risk assessment estimates a measure of the chances that someone may get cancer because they have been exposed to a drinking water contaminant. EPA generally sets maximum contaminant levels MCLs at levels that will limit individuals risk of cancer from that contaminant to between 1 in 10,000 and 1 in 1,000,000 over a lifetime. For non-cancer effects, the risk assessment estimates an exposure level below which no adverse effects are expected to occur.

The EPA has considered Point of Entry (POE) and Point of Use (POU) as a viable treatment technology for small communities with less than 1000 people but will only allow them to be used by a treatment utility NOT by the individual homeowner. This will make certain that there is accountability for the service of the equipment. The EPA has also required pre-oxidation in single house or single treatment situations. This means that if you have your own well system and you plan on using reverse osmosis or any other of the above technologies you must first use chlorine to oxidize your well water. This will convert any As-III species of arsenic to As-V so that it is more readily removed by your treatment options.

Community water systems that serve large populations of people that will be over the new standard of 5 ppb will need to start being retrofited with the necessary equipment to keep the system within the new 5 ppm standard.

Treatment for arsenic is readily available to community water treatment systems. The treatment technologies that have been considered by the EPA as viable methods of treatment for bringing arsenic levels to below the new 5 ppb standard are as follows

In no particular order of effectiveness
Coagulation/Filtration (C/F)
Activated Alumina (AA)
Ion Exchange (IX)
Ultrafiltration (UF)
Nanofiltration (NF)
Reverse Osmosis (RO)
Greensand Filtration (GF)
Lime Softening (LS)

As development in our modern society increases, there are a growing number of threats that could contaminate our drinking water. Suburban sprawl has encroached upon once-pristine watersheds, bringing with it all of the by-products of our modern life style. Actual events of serious drinking water contamination occur seldom in this country, although in the country Bangladesh high levels of Arsenic in numerous shallow and deep wells in various parts of the country has raised serious health concerns. Recent investigations, though incomplete, confirm that the occurrence of Arsenic in groundwater is more widespread than assumed at first and that it already affects a large number of people. The latest statistics available on arsenic contamination in the groundwater indicates that 59 districts around 85% of the total area of Bangladesh and about 75 million people are at risk. It is estimated that at least 1.2 million people are exposed to Arsenic poisoning and 24 million potentially exposed. With the threats of such events increasing, we cannot take drinking water safety for granted. Greater vigilance by you, your water supplier, and your government is vital to ensure that such events do not occur in your water supply.

For more information, please contact R/O CONN at (602) 432-5402 or fax (602) 942-1451. Or you can E-mail us at

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