In a move that could put U.S. EPA Administrator Christie Todd Whitman in the hot seat again, a scientific advisory committee to the EPA voted unanimously yesterday to send on a long-delayed report to the agency that concludes that dioxin should be more tightly regulated. The committee found that dioxin is an air pollutant that causes cancer in lab animals and possibly in humans, a shift from a draft of the study leaked a year ago that said more bluntly that dioxin be classified as a human carcinogen. Still, the chemical and paper industries, which account for a significant amount of dioxin emissions, were none too happy that the study has proceeded beyond the committee stage.