Arsenic in Drinking Water
Arsenic is a naturally occurring element present in rocks and soil. Arsenic is the 20th most abundant element in the earth's crust and often forms inorganic compounds by combining with oxygen, chlorine and sulfur. As water passes through and over soil and rock formations, it dissolves many compounds and minerals including arsenic. The result is that varying amounts of soluble arsenic are present in some water sources. Arsenic chemistry is complex, because it has many forms.
Arsenic contamination of a drinking water source most often results from natural sources; however, it can result from human activities. Arsenic solutions were used to treat a variety of health disorders in the past. While the medical use of arsenic has declined, an arsenic solution received Food and Drug Administration approval for leukemia treatment in 2000. Arsenic has been used in mining and manufacturing and was a component of some pesticides used in the past. Chromated copper arsenate was used to pressure-treat wood for preservation and to prevent insect damage; this wood commonly was known as CCA-treated lumber.
Although arsenic use as described above has the potential to result in arsenic contamination of groundwater, primarily as a result of industrial activity, the arsenic in most Nebraska water supplies is naturally occurring and comes from the aquifer from which the water is pumped.
Potential Health Effects
Arsenic exposure can cause a variety of adverse health effects. The severity of the effect depends on how much arsenic is in the water, how much water is consumed, how long a person has been drinking the water, and a person's general health. Arsenic poisoning can be acute or chronic. Acute poisoning can occur when a high concentration (over 60 mg/L) of arsenic is ingested over a short time. This is more likely to occur where arsenic has been concentrated by industrial processes or at unregulated waste disposal sites. Chronic poisoning can occur when moderate or small amounts of arsenic are ingested over long periods (usually five years or longer), such as where groundwater containing arsenic is consumed daily for extended periods. Some Nebraska groundwater supplies contain arsenic in high enough concentrations to present a risk of chronic poisoning. Arsenic is a known carcinogen, and long-term ingestion may increase the risk of cancer.
Uncertainty exists in arsenic risk assessment, and more research must be done to determine the connections between level of arsenic, duration of exposure, and health effects. However, studies summarized in a recent report by the National Research Council point to a preponderance of evidence that long-term ingestion of arsenic can increase the risk of skin, bladder, lung, kidney, liver, and prostate cancer. Non-cancer effects of ingesting arsenic may include cardiovascular, pulmonary, immunological, neurological effects, and endocrine problems such as diabetes.
Symptoms of chronic arsenic poisoning are usually delayed, with years of exposure required to initiate the disease process. Factors such as genetics, age, metabolism, diet and overall health may also impact health risks associated with arsenic exposure, because they potentially affect one's ability to clear arsenic from the system. Indi
