In addition, this final rule also clarifies how compliance is demonstrated for many inorganic and organic contaminants in drinking water. When a system fails to collect the required number of samples, compliance averages will be based on the actual number of samples collected. Also, new public water systems and systems using new sources of water must demonstrate compliance within State-specified time and sampling frequencies. EPA published the proposed rule for arsenic on June 22, 2000. In most drinking water sources, the inorganic form of arsenic tends to be more predominant than organic forms.
Studies link inorganic arsenic ingestion to a number of health effects.
The contamination of a drinking water source by arsenic can result from either natural or human activities. Arsenic is an element that occurs naturally in rocks and soil, water, air, plants, and animals. Volcanic activity, the erosion of rocks and minerals, and forest fires are natural sources that can release arsenic into the environment. Although about 90 percent of the arsenic used by industry in the United States is currently used for wood preservative purposes, arsenic is also used in paints, drugs, dyes, soaps, metals and semi-conductors. Agricultural applications, mining, and smelting also contribute to arsenic releases.