Even as they cheer U.S. EPA’s first steps toward a drinking water standard for perchlorate, environmental and public health groups are warily predicting Pentagon and industry resistance to proposed limits on the rocket fuel chemical during a behind-the-scenes federal review process.

EPA sent an initial determination on perchlorate to reviewers at the White House budget office last Wednesday, more than a year after first seeking input on revisiting the George W. Bush administration’s refusal to regulate its presence in drinking water. The agency’s move was widely acknowledged as a reversal of that 2008 decision, setting the stage for new curbs on a contaminant that can impede thyroid functioning at high doses — particularly among children and pregnant women.

But EPA’s initial foray toward using its Safe Drinking Water Act authority against perchlorate is only the first step in a lengthy process that begins at the White House Office of Information and Regulatory Affairs (OIRA), an arm of the Office of Management and Budget where federal agencies and private-sector interests weigh in on the economic impact of potential new rules.