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. The average annual household costs are shown categorized by system size in Table 3. The disparity in household costs between systems sizes is due to economies of scale.
Larger systems are able to spread the costs they incur over a larger customer base.
The benefit range consists of both lower and upper bound estimates. These estimates reflect the upper and lower bound of the risk range addresssed by this rule as well as different drinking water consumption distributions that were used in our analysis. Other federal funds are available through Housing and Urban Development's Community Development Block Grant Program, and the Rural Utilities Service of the U.S. Department of Agriculture. From 1997-1999, EPA conducted a number of Agency workgroup meetings on arsenic as well as five stakeholder meetings across the country. Five States also provided written comments on implementation issues during the rule development process.