Provoking jeers from environmentalists, the U.S. EPA said yesterday that it would delay until next February a decision on how much arsenic should be allowed in drinking water. A rule approved by former President Clinton would have changed the current standard of 50 parts per billion of arsenic in water, first set in 1942, to 10 ppb, the same level recommended by the World Health Organization. But the Bush administration revoked the rule in March, saying it wasn’t based on “sound science.” EPA Administrator Christie Todd Whitman at first said her agency would propose a new standard by this summer, but yesterday said more time was needed to allow the National Academy of Sciences to review the latest studies on arsenic.