EPA flip-flops on final arsenic rule

The following column was written just a few days before the newly tightened 10 ppb arsenic dr-inking water standard was scheduled to take effect on March 23. However the White House suspended the rule on March 20, pending further review. This is a rule that had been in progress since approximately 1987, and had been extensively reviewed by the National Academy of Sciences (NAS) drinking water utilities, and other stakeholders. There was a significant public outcry against this action, so on April 23 the EPA published another notice about the rule (Federal Register 66(78), 20579-20584). It delays implementation of the final rule until February 22, 2002. EPA has asked the NAS to review this rule (again!), and to incorporate any studies published since the 1999 review. According to a senior EPA scientist, a key toxicology issue is the behavior of arsenic's dose-response relationship at low doses. EPA has also asked the National Drinking Water Advisory Council to review the cost compliance estimates. There is a fair likelihood the final standard will be 20 ppb.