UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

 WASHINGTON D.C. 20460 

 

OFFICE OF THE ADMINISTRATOR 

SCIENCE ADVISORY BOARD 

November 5, 2008 

The Honorable Stephen L. Johnson 

Administrator 

U.S. Environmental Protection Agency 

1200 Pennsylvania Avenue, N.W.

Washington, D.C. 20460 

Dear Administrator Johnson: 

Thank you for your memorandum of October 20, 2008, requesting that the Science 

Advisory Board (SAB) undertake a study to provide advice on how EPA can strengthen 

scientific assessments, better communicate the results of assessments, and integrate natural 

science assessment with economic and social assessments to support EPA decision making. I 

had the opportunity to discuss the request with my colleagues this week at a public advisory 

meeting of the chartered SAB. We will undertake this effort with the goal of providing advice to

the new EPA Administrator within a year. 

At our public meeting on October 28, 2008, the chartered SAB also discussed a draft 

report from the SAB's Drinking Water Committee on EPA's Draft Third Drinking Water 

Contaminant Candidate List (CCL3). The Committee’s draft report highlighted its 

recommendation that perchlorate is one of four chemicals that "should be a high priority for 

consideration by the Agency, because there is a higher degree of certainty about their toxicity, 

occurrence, and treatability." 

The SAB is also aware that EPA published a Drinking Water: Preliminary Regulatory 

Determination on Perchlorate in the Federal Register on October 10, 2008 (73 FR 60262-60282). 

That notice provides a preliminary determination that "a national primary drinking water 

regulation (NPDWR) for perchlorate would not present 'a meaningful opportunity for health risk 

reduction for persons served by public water systems'" and provides a thirty-day public comment 

period. The notice also states that EPA plans to issue a final regulatory determination by 

December 2008. It should be noted that this preliminary determination relies on the use of a 

dosimetric model which is now undergoing letter peer review, and thus, its soundness will not be 

publicly vetted. 
Given perchlorate's wide occurrence and well-documented toxicity to humans, the SAB 

strongly believes that there must be a compelling scientific basis to support a determination not 

to regulate perchlorate as a national drinking water contaminant. The quality of the scientific 

foundation for EPA's decisions depends on peer review, which brings a variety of scientific 

perspectives to bear on critical components of EPA's decisions. Where science assessments have 

been conducted with the benefit of external scrutiny, the end products have been better able to 

support the policy making process. This view is very much aligned with the perspectives 

expressed in your memorandum to the SAB. 

As you know, the SAB operates under the requirements of the Federal Advisory 

Committee Act for advance notice of public meetings. Therefore, the SAB will not be able to 

provide you with our comments regarding the scientific basis of this determination in time to 

meet the Agency’s deadline of November 10, 2008. Accordingly, the SAB urges the Agency to 

consider extending the public comment period thereby allowing us to provide comments for the 

Agency’s consideration in making the final regulatory determination on perchlorate. Thank you 

in advance for your consideration. 

 Sincerely,

 

 /Signed/ /Signed/

Dr. Deborah L. Swackhamer, Chair Dr. Joan Rose, Chair 

 Science Advisory Board SAB Drinking Water Committee 

cc: Marcus Peacock, Deputy Administrator 

 Ben Grumbles, Assistant Administrator, Office of Water 

 Cynthia Dougherty, Office of Water 

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