[CPEO-MEF] California re-affirms perchlorate public health goal of 6 ppb

[Lenny Siegel <lsiegel@cpeo.org>]

[As I read this statement, California took a second look at its Public
Health Goal for perchlorate (6 parts per billion in drinking water)
after the National Academy of Science's report, and decided not to
change it. This clears the way for promulgation of an MCL (Maximum
Contaminant Level) - LS]

FOR IMMEDIATE RELEASE:
Release No. 05- 02
April 1, 2005
www.oehha.ca.gov

State's Drinking Water Goal For Perchlorate
Consistent With Findings Of Major Federal Study

SACRAMENTO - The California Environmental Protection Agency's Office of
Environmental Health Hazard Assessment (OEHHA) today announced that the
state's Public Health Goal (PHG) for perchlorate in drinking water is
consistent with the findings of a recent report on the chemical by the
National Academy of Sciences (NAS).  In light of the favorable NAS
findings, OEHHA has determined that the PHG does not need to be revised.

The PHG, which was published in March 2004, identifies 6 parts per
billion as a level of perchlorate in drinking water that does not cause
or contribute to adverse health effects.  Perchlorate is primarily
produced for use in rocket fuel, explosives, fireworks, road flares and
air-bag inflation systems, and has been detected in a number of
California drinking water sources.  

"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 report, released in January 2005, evaluated the U.S.
Environmental Protection Agency's 2002 Draft Toxicological and Risk
Characterization for Perchlorate.  In its report, the NAS examined
scientific issues that were relevant to OEHHA's PHG for perchlorate. 
When it published the PHG in 2004, OEHHA announced it would review the
NAS report upon its completion and, if necessary, revise the PHG.  OEHHA
has concluded no revision is needed because of the consistency between
the NAS findings and OEHHA's assessment of perchlorate.

The key NAS findings were:

* The health effects of perchlorate should be assessed using data from
clinical studies involving humans, rather than laboratory animals.  The
NAS specifically recommended the use of a well-regarded 2002 study in
which healthy volunteers were administered perchlorate.  OEHHA used that
same study to assess perchlorate's health effects and develop the PHG.

* The perchlorate health effect of primary concern is the reduction of
the uptake of iodide, an essential nutrient, by the thyroid gland (a
butterfly-shaped gland in the throat).  While not harmful by itself,
inadequate iodide uptake may lead to the harmful disruption of proper
thyroid function.  The NAS report said that the initial reduction of
iodide uptake "is the key event that precedes all...effects of
perchlorate exposure," and that focusing on the reduction of iodide
uptake "is the most health protective and scientifically valid
approach."  OEHHA's perchlorate assessment similarly focused on the
reduction of iodide uptake as the critical health effect.  

* The fetuses of pregnant women are "the most sensitive population" to
perchlorate's health effects, the NAS report said.  OEHHA similarly
concluded that pregnant women and fetuses were most sensitive to
perchlorate after evaluating the chemical's health effects on adults,
infants and lactating women, as well as pregnant women and fetuses.  To
ensure that a perchlorate assessment does not underestimate the
chemical's effects on pregnant women and fetuses, the NAS recommended
the same approach that OEHHA used in developing its PHG.  

OEHHA did not identify any findings or recommendations in the report
that conflicted with its PHG assessment.  OEHHA and the NAS chose
different methods for identifying general levels of perchlorate exposure
that would not cause health effects, but the NAS report did not disagree
with the method used by OEHHA.  The NAS report did not calculate a safe
level of perchlorate in drinking water, as this was outside the request
made to the NAS.  

In publishing the PHG, OEHHA used data from the 2002 study cited by NAS
to identify 6 parts per billion as a level of perchlorate in drinking
water that is protective of human health, including the health of
pregnant women and fetuses.  Impairment of thyroid function in pregnant
women may affect the fetus and result in delayed development and
decreased learning capability.  

In a parallel development, OEHHA announced that a newly released study
of perchlorate levels in human breast milk did not produce sufficient
information to justify any revisions to the PHG.  The study, published
in February 2005 and authored by three Texas Tech University
researchers, found elevated levels of perchlorate in breast milk samples
from throughout the United States, including California.  While
important, the study did not find any correlation between perchlorate
levels in the breast milk and drinking water of study participants, and
was not designed to identify the sources of the perchlorate found in
breast milk.  

OEHHA will continue to monitor new scientific developments concerning
perchlorate.  State law requires OEHHA to review and, as necessary,
update each PHG every five years. 

State law next requires the California Department of Health Services
(DHS) to set a regulatory drinking water standard for perchlorate that
is as close to the PHG as is economically and technically feasible.  A
PHG is not a regulatory requirement, and it is not a boundary between
"safe" and "dangerous" levels of a chemical in drinking water.  PHGs are
health-protective goals for drinking water contaminants that DHS uses in
establishing drinking water standards.  OEHHA develops PHGs for all
regulated drinking water contaminants.

The Office of Environmental Health Hazard Assessment is one of six
entities within the California Environmental Protection Agency.  OEHHA's
mission is to protect and enhance public health and the environment by
objective scientific evaluation of risks posed by hazardous substances.


-- 


Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org
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