The Bush Administration’s Last Words on Perchlorate

After years of study and analysis on the public health implications of regulating perchlorate in drinking water, EPA has come to the conclusion that … it needs to do more study and analysis.

In fact, that is the conclusion of two different EPA offices. Within a two-week span, EPA’s Office of Water and its Office of the Inspector General each issued a report suggesting that the agency should refrain from regulating the chemical until more research clarifies various uncertainties.

On December 30, EPA’s Inspector General released a report that faulted both EPA and the National Academy of Sciences for failing to use cumulative risk assessment techniques to derive the reference dose for perchlorate. The Office of the Inspector General hired a contractor to review EPA’s and NAS’s work, and provided this summary:

Based on our scientific analysis documented in our report, perchlorate is only one of many chemicals that stress the thyroid’s ability to uptake iodide. The other NIS sodium iodide symporter stressors include thiocyanate, nitrate, and the lack of iodide. All four of these NIS stressors meet EPA’s risk assessment guidance for conducting a cumulative risk assessment using the dose addition method. Our analysis includes a cumulative risk assessment of this public health issue using all four NIS stressors. A cumulative risk assessment approach is required to better characterize the risk to the public from a low total iodide uptake (TIU) during pregnancy and lactation. Further, a cumulative risk assessment approach is required to identify potential actions that will effectively lower the risk to public health.

There are a lot of interesting things going on here. For one thing, OIG is right that cumulative risk assessment is the best way to understand the risks we confront in the “real world.” But doing a cumulative risk assessment on perchlorate would likely lead to a higher reference dose, which could prevent EPA from ever mandating a perchlorate drinking water standard. The Safe Drinking Water Act (SDWA) takes a contaminant-by-contaminant approach to regulation, saddling EPA with regulatory tools that do not mesh well with the analytical capabilities of cumulative risk assessment. So using state-of-the-art cumulative risk assessments might lead to more contentious science-policy decisions by EPA Administrators.

Another interesting thing about the OIG report is that OIG hired a private consulting firm and paid it tens of thousands of dollars to check up on scientific research that EPA did on its own and then paid NAS to peer review. NAS is comprised of the country’s top scientists and operates under statutory requirements that review committees be balanced for bias and free of conflicts of interest. It is unclear from the OIG report what safeguards were put in place to ensure that the consultants were hired under similar constraints. This is a particularly important question given that the OIG report does not clearly identify why the Inspector General undertook the task of writing this report in the first place. The only hint at a justification was a reference to two pieces of legislation from the 110th Congress that would require EPA to regulate perchlorate under the SDWA.

A week after the Office of the Inspector General released its report, EPA’s Office of Water released an “interim health advisory” on perchlorate, a move that forestalls more stringent health-protective action. So rather than taking proactive steps to regulate perchlorate under the Safe Drinking Water Act, EPA is simply advising the public about the threats of drinking water contaminated with the chemical. While the public and the local officials in charge of keeping our tap water clean wonder what to do with this information, EPA plans to go back to the National Academy of Sciences to ask for more advice.

As I pointed out last month, many observers were expecting EPA to make a final regulatory determination not to regulate perchlorate under the SDWA. EPA hasn’t done that. Realistically, punting the final decision to the Obama Administration could ultimately result in a stronger standard. Of course, it would be better for EPA to work actively on getting perchlorate out of our water supplies right away, but at least the agency hasn’t finalized a bad decision that would take years to undo.