ARSENIC: MOVING TOWARD A REGULATION.
Ira W. Leighton.
U.S. Environmental Protection Agency, Region 1, Boston MA 02114.

The U.S. Environmental Protection Agency (EPA) has spent much of 2001 reviewing the arsenic standard so that communities that need to reduce arsenic in drinking water can proceed with confidence that the new standard is based on sound science and accurate cost and benefit analyses. The Safe Drinking Water Act, as amended in 1996, required EPA to review current drinking-water standards for arsenic, propose a maximum contaminant level for arsenic by January 1, 2000, and issue a final regulation by January, 2001. EPA published a new standard for arsenic in drinking water on January 22, 2001 that would require public water supplies to reduce arsenic to 10 ppb by 2006. EPA withdrew the standard in March 2001 for review. Many small communities will be affected by the drinking water standard for arsenic, making it especially important to ensure that the Safe Drinking Water Act provision allowing balancing of cost, is based on accurate information. On May 22, 2001 EPA extended the previous delay of the rule's effective date to February 22, 2002 but did not change the compliance date (2006) for systems. On October 31, 2001, EPA affirmed the appropriateness of a maximum contaminant level (MCL) of 10 parts per billion for arsenic in drinking water. EPA believes setting the arsenic level at 10 parts per billion will provide additional protection to at least 13 million Americans.