Arsenic in Drinking Water

The world has been alerted to the reality of arsenic in drinking water through the recent experience of Bangladesh. Because of the exposure of their population to high levels of arsenic, it is estimated that hundreds of thousands of people there are likely to die from arsenic poisoning. And it comes from their drinking water, from wells that have been poisoned through natural causes, that is, arsenic in the rocks and soil of the country getting into the underground water supply.

At the recent Annual Conference of the Royal Geographical Society held in August 2007, it was stated that new research has revealed that arsenic in drinking water is threatening the health of people in more than 70 countries around the world.

Question #1: What is Arsenic?

Arsenic is called a "semi-metal" in the periodic table. It is odorless and tasteless. There are two forms of arsenic that are found in water: 1) Pentavalent Arsenic which is sometimes called Arsenic 5 or Arsenate and 2) Trivalent Arsenic which is sometimes called Arsenic 3 or Arsenite.

Arsenic has many uses in agriculture and industry. It is used in paints, dyes, metals, drugs, soap and semiconductors. In agriculture it is used in fertilizers and animal feeding. It is estimated that 90% of industrial arsenic in the United States is used as a wood preservative.

Question #2: How does Arsenic get into our drinking water?

By far the largest source of arsenic in drinking water is in natural deposits in the rocks and soil of the earth's crust. When underground water levels drop, this releases arsenic from rock formations into the water which then pollutes well water. Other natural sources of arsenic include air, plants, and animals. Volcanic explosions, forest fires and the burning of coal all release arsenic into the atmosphere, which in turn can be carried by the wind and deposited elsewhere.

Added to these natural sources of arsenic in drinking water the man made sources. In the past, arsenic was used primarily in pesticides. We now use synthetic organic pesticides in its place. However, runoff water from orchards and from glass and electronic production wastes still pollute our drinking water with arsenic.

Question #3: How can arsenic in drinking water affect my health?

Dr. Allan Smith of the University of California Berkeley says of arsenic, "It is the most dangerous contaminant of drinking water in terms of long-term health risks." It is one of a relatively small number of chemicals that is known to cause cancer. It increases the risk of cancer of the bladder, lungs, skin, kidneys, liver and prostate. These are some of the long-term health effects, effects of drinking even small amounts of arsenic over a long period of time.

There are also short-term effects to high levels of arsenic. The list of possible effects is long: thickening and discoloration of the skin, stomach pain, nausea, vomiting, diarrhea, numbness in hands and feet, partial paralysis and blindness.

Question #4: How serious a problem is arsenic in our drinking water?

As I mentioned in my introduction to arsenic, it is a major health problem to the world community. Dr. Peter Ravenscroff at the above mentioned conference in London stated "that an estimated 137 million people are being unknowingly exposed to unsafe levels of arsenic in their drinking water." He goes on to say that, of these, 57 million at levels of arsenic of more than 50 ppb (The level of safety is 10 ppb.)

Besides Bangladesh, people in Taiwan, Chile and Argentina are exposed to high levels of arsenic in drinking water. In the United States, there are hot spots, but in general the levels of arsenic in drinking water are controlled by local water systems. Western States have more water systems with arsenic levels greater than the Environmental Protection Agency's level of safety (10 ppb). In parts of the Midwest and New England there are some systems with higher levels of arsenic.

If your tap water is taken from underground sources, there is a greater chance of it having higher levels of arsenic than if it is taken from surface water such as lakes, rivers and reservoirs. If you get your tap water from a private well, it is important to have your water tested for arsenic.

Question #5: How can I know if arsenic is in my drinking water?

If you get your tap water from a public water system, they are required by law to send you annually a Consumer Confidence Report (CCR). If you don't have a copy you can get one from your city hall. Look to see if there is arsenic in your water and how much. They cite the "Level Found" and the "MCL" (Maximum Contaminant Level). For arsenic, the standard set by the EPA is .010 mg/L (milligrams per liter). Any water which has more than this amount of arsenic is not safe. The water company is required to state in their CCR that arsenic is over the MCL limit and what they are doing to correct this. They are also required to inform the public through newspapers and television that the level of arsenic is over the level of safety.

If you get your tap water from a private well, it is recommended that you have it tested for arsenic and other pollutants that may make it unsafe to drink as is. You can order a water testing kit and test it yourself or hire a water testing laboratory in your area to do it for you.

The MCL (Maximum Contaminant Level) of arsenic was initially set by the Safe Drinking Water Act at 0.05mg/L and then revised down to 0.01mg/L in l993 after the World Health Organization recommended this as the level below which arsenic will do you no health damage.

Question #6: How would I go about removing arsenic from my drinking water?

There are three kinds of filters that can remove arsenic from your tap water: Distillation, Reverse Osmosis, and Filtration (granular or carbon block). However, you need to check the individual filter that you are considering to not only see if they claim to reduce arsenic, but if this has been certified by the NSF International as a filter that does indeed effectively reduce arsenic.

For further information on the best filters in the categories of Distillation, Reverse Osmosis and Filtration go to "Best Water Filters". Or for a broader discussion of the multiple considerations you need to keep in mind in selecting a filter go to "How to Choose a Water Filter".

For more information about arsenic and other toxic contaminants, go to "Arsenic in Drinking Water".

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