Arsenic is a naturally occurring element widely present in the environment. All humans are exposed to low levels of arsenic on a daily basis from food, water and air.It’s important to have water tested for arsenic because it imparts no odor, taste, or discoloration to indicate it’s presence.
Arsenic can enter the drinking water from various sources. Arsenic found in well water typically is from geologic formations containing arsenic compounds. Arsenic may also enter water supplies from waste chemical disposal sites. Arsenic is a common ingredient in many pesticides and wood preservatives; it can enter the water supply due to widespread use and improper applications.
Exposure to high and low levels of arsenic can result in several different health effects. Health effects of acute arsenic poisoning include jaundice, liver abnormalities, lung congestions, and kidney failure, nerve disorders. Symptoms of acute exposure include headaches, confusions, hallucinations, seizures, loss of vision, muscle weakness and numbness in legs and arms. Chronic exposure to arsenic can result in skin and nail lesions, notable changes in pigmentation, thickening of palms and soles and hair loss. Eventually those skin disorders can lead to skin cancers.
How is arsenic regulated?
On October 3, 2001 the EPA finalized the new arsenic rule. This rules revised the old Maximum Contaminant Level from 50 parts per billion down to 10 parts per billion. According to the EPA’s Science Advisory Board, reducing the arsenic level will prevent 5-8 deaths from this cancer, 19-25 cases of lung cancer, preventing 16-22 deaths; and numerous other non-cancerous diseases such as diabetes and heart disease.
How is arsenic tested?
There are field tests available, which can indicate a presence. These tests do not meet monitoring requirements for public water supplies, but may be useful in screening or monitoring a treatment system. Since arsenic is a health-based contaminant you should have the water analyzed using a laboratory.
Laboratories analyzing drinking water samples can utilize various methods including EPA method 200.7 and 200.8 which utilize an Inductively Coupled Plasma (ICP) or the Standards Method 31138 which uses Graphite Furnace.
How is arsenic treated?
In drinking water there are two species of Arsenic: arsenite (As+3) and arenate (As+5). Arsenate is more common in surface water while arsenite is more prevalent in groundwater. The EPA has reviewed several treatment techniques and found the following meet the requirement under the Safe Drinking Water Act (SOWA) for best available technologies: Ion Exchange, Activated Alumina, Reverse Osmosis, Modified Coagulation/Filtration, Modified Lime Softening, and Electrodialysis Reversal. Aresnate is removed more efficiently than the arsenite, so pre-oxidation is recommended to convert arsenite into arsenate. Data shows chlorine, potassium permanganate and ozone are effective for converting the arsenite into arsenate. The EPA is still investigating the use of ultraviolet light technology and solid oxidizing media for the conversion.