The U.S. Environmental Protection Agency (EPA) recently called for further study of a substance found in rocket fuel before regulation of the contaminant can occur. A Senate champion of environmental protections criticized the decision, which is the latest delay in a regulatory policy EPA has been developing since 1998.

On April 12, EPA stated the agency will not regulate the drinking water contaminant perchlorate, an ingredient in rocket fuel and fireworks. The National Academies of Science (NAS) found perchlorate commonly present in public drinking water supplies and found ingestion to inhibit human thyroid function. The EPA cited the need for further investigation in its decision not to regulate perchlorate.

Sen. Barbara Boxer (D-CA) issued a statement chiding EPA for its decision. Boxer is a supporter of perchlorate regulation and has introduced two bills during the current Senate. One bill (S. 150) would mandate EPA to set a standard for perchlorate exposure, and the other (S. 24) would improve drinking water testing. Boxer said, "I am outraged that EPA has yet again refused to do its duty to protect the health of our families and communities from perchlorate pollution."

Much of Boxer's displeasure stems from the amount of time EPA has spent developing perchlorate regulations. EPA first addressed the issue of perchlorate contamination in 1998 but has shown little progress in advancing regulations.

During the Clinton administration, EPA began studying perchlorate with the intent of promulgating regulations to improve public health related to exposure. In 1998, the agency released its first assessment, which was then peer reviewed. In 1999, EPA issued interim guidance on perchlorate. The interim guidance intended to provide information on exposure levels for both EPA and non-EPA researchers.

In 2002, EPA released a revised assessment of perchlorate based on the initial 1998 assessment. The White House then asked NAS to peer review that document and make recommendations. NAS issued its report in January 2005. In 2006, EPA replaced the 1999 interim guidance with new interim guidance, which adopted the recommendations of the NAS report. The new interim guidance, the current framework for assessing perchlorate, suggests a more definitive exposure level for research purposes.

However, the Natural Resources Defense Council (NRDC) found the White House and Pentagon had exerted political influence over the formation of the NAS study group, as well as the study itself. Because of the potential liability for defense contractors, political appointees urged NAS to downplay the danger of perchlorate, according to NRDC. It is unclear to what extent the political pressure altered the study's findings because, according to NRDC, "the White House, DOD and EPA have attempted to cover up their campaign to pressure NAS and to undermine efforts to address perchlorate pollution by unlawfully withholding or redacting an unprecedented number of documents."

Public skepticism over the commitment of the Bush administration to promulgate perchlorate regulations increased in December 2006 when EPA finalized a rule for monitoring drinking water contaminants. The proposed rule included perchlorate as one of the contaminants, but EPA removed it from the list in the final rule. Critics accused EPA of bowing to industry's wishes.

Now, EPA has missed yet another opportunity to begin regulating drinking water for perchlorate contamination. Under the Safe Drinking Water Act, EPA must propose candidate contaminants every five years and, after a review period, begin regulating those it deems necessary. In 2005, EPA issued a contaminant candidate list of 51 chemicals, of which perchlorate was one. However, EPA's April 12 statement proposes to exclude perchlorate, along with 12 other chemicals, from the final list of regulated contaminants.

In the statement, EPA claims perchlorate "require[s] additional investigation to ascertain total human exposure and health risks." EPA's decision will be open for public comment for 60 days following its publication in the Federal Register.