California Affirms Perchlorate PHG

April 11, 2005

As expected, California environmental health hazard officials have determined that the perchlorate public health goal (PHG) of 6 micrograms/L set last year "is consistent with" the recent findings by an expert panel from the National Academy of Sciences (NAS) on the health implications of perchlorate ingestion.

Announced in early April by the state's Office of Environmental Health Hazard Assessment (OEHHA), the decision sets the stage for California drinking water officials to propose a perchlorate standard this year as required by state law. When it set the perchlorate PHG in March 2004, OEHHA committed to reviewing it against the NAS report, which was completed in January.

"The National Academy of Sciences report on perchlorate provides strong support for the approach that we took in developing our public health goal," OEHHA Director Dr. Joan E. Denton said. "The federal report, along with earlier peer reviews of our perchlorate assessment by University of California scientists, reinforces the solid scientific foundation that underlies California's efforts to safeguard drinking water from threats posed by perchlorate."

The NAS panel recommended a perchlorate reference dose of 0.7 micrograms/kg/day, which USEPA subsequently adopted and used to calculate a drinking water equivalent level (DWEL) of 24.5 micrograms/L.

Acknowledging that it used a different method than NAS "to identify general levels of perchlorate exposure that would not cause health effects," OEHHA concluded that it "did not identify any findings or recommendations in the report that conflicted with its PHG assessment."

OEHHA specifically addressed concerns raised by those who sought either a tougher or less stringent PHG, concluding that "the arguments that have been offered are essentially the same as considered earlier by OEHHA and also by the NAS committee."

Among those urging a less stringent PHG was the Council on Water Quality (CWQ), a group of perchlorate producers that includes the Perchlorate Study Group. CWQ responded to OEHHA's decision by cautioning that, "To the extent California's PHG is not based on the best available science, the resulting maximum contaminant level could be unnecessarily restrictive and costly, forcing local governments to divert resources away from more pressing needs, while still not providing corresponding health benefits."

OEHHA also issued a question and answer document that further details its review, which also included a determination not to consider recent research on perchlorate levels in breast milk because it did not address the source of perchlorate.

"OEHHA would need additional data on the sources of the perchlorate before it could review or revise its PHG calculation that account for perchlorate exposures from food and other non-drinking water sources," the agency stated, noting that state law requires PHGs to be reviewed every five years.

Source: WEF