Facts on Arsenic Levels in Water

Unregulated concentrations of arsenic in water impair human health, but maintaining low levels of arsenic in water expends great quantities of capital, time and manpower. In developed countries such as the United States, water contaminated with significant amounts of arsenic is almost nonexistent. The U.S. Environmental Protection Agency governs the allowable quantity of arsenic in water, routinely mandating testing and removal of the element. On the other hand, underdeveloped countries found in Asia, South America and Africa have difficulties keeping their water supplies from contamination by toxic concentrations of arsenic. These nations generally cannot fund water-purifying measures, so their people have no choice but to use polluted rivers and underground wells sourced by contaminated groundwater.

Sources of Arsenic

• Volcanic eruptions provide a natural source of arsenic.

  Arsenic is present in trace amounts throughout nature, in the air, soil, water and bodies of organisms. Certain manufacturing industries such as pesticide production also require the presence of arsenic. Natural phenomena such as volcanic eruptions and fires also provide significant sources of arsenic. Any of these sources may result in arsenic leaching into the water supply, especially pooling into groundwater sources.

Regulation

• The EPA regulates arsenic levels in water. In 1975, the EPA set the arsenic standard of 50 ppb, which denotes a limit of 50 parts of arsenic per billion parts of water. Because of numerous studies detailing the adverse health effects stemming from consumption of arsenic, the National Academy of Sciences issued a report in 1999 warning that the existing standard was still too toxic for humans. As a consequence of this recommendation, the EPA lowered the limit in 2001 to a mere 10 ppb.

Detection

• Local governments systematically test for levels of arsenic in drinking water and other water sources, but the techniques lie within expensive laboratories and complicated methods such as atomic absorption spectrometry. Several inexpensive kits exist for purchase by the consumer should you feel the need to determine arsenic levels in water sources on your property. The kits use test strips to recognize a chemical reaction that identifies the amount of arsenic in water samples within half an hour.

Health Effects

• Intake of arsenic, even at low levels, has detrimental effects on the human body. Arsenic is a known carcinogen, a cancer-causing agent. In 1968, W.P. Tseng studied villages in Taiwan, China, showing a correlation between increased incidences of skin cancer in the villagers and concentrations of arsenic in the drinking water. A 1998 study lead by C. Hopenhayn-Rich noted that consumption of arsenic-contaminated drinking water directly corresponded to increased cases of internal cancers, such as those of the kidneys, liver, lungs and stomach.

  Arsenic also causes non-cancerous conditions, mainly skin related. Those exposed to arsenic developed pigmentation problems where certain light or dark spots appeared on the skin. Keratosis, a medical condition in which the skin toughens and develops into protuberances, appeared on the hands and feet of sufferers. Tseng also found a high incidence of blackfoot disease, or peripheral vascular disease, among Taiwanese villagers. Blackfoot disease causes the tissues of the hands and feet to die, leaving blackened stumps. Arsenic may lead to diabetes, high blood pressure, heart disease, liver abnormalities and lung dysfunction.

Treatment

• The treatment of public water supplies contaminated with arsenic employs one of several expensive and highly-technical processes. In chemical precipitation, certain substances added to the water combine with arsenic to yield crystals that are easy to remove. Adsorption allows arsenic to bind to the surface of a sticky, aluminum-containing substance called alumina. Ion exchange removes arsenic from water by using a chemical with a negative charge to attract the positively-charged arsenic particles. Finally, reverse osmosis forces arsenic-laden water through a membrane, a thin barrier that prevents the passage of substances other than water molecules. These substances, including arsenic, are removed. Of the four processes described, only chemical precipitation proves too inefficient for private use.