[CPEO-MEF] NAS re-clarification on perchlorate

[Lenny Siegel <lsiegel@cpeo.org>]

On February 7, 2005, the National Academy of Sciences sent a letter to
the Environmental Working Group re-clarifying that the National Research
Council's recent report, Health Implications of Perchlorate Ingestion,
did not recommend a drinking water standard for perchlorate, and that
numerous factors should be considered in developing drinking water goals
from the committee's recommended daily reference dose.

That letter is available as a PDF file on EWG's web site,
http://www.ewg.org. Scroll down on the left. I have keyed the letter in
as text below, and I have also copied related correspondence from EWG's
web site, in reverse chronological order.

LS

***

The National Academies
Board on Environmental Studies and Toxicology
500 Fifth Street, NW
Washington, DC 20001

February 7, 2005

Mr. Ken Cook
President
Environmental Working Group
1436 U Street, NW - Suite 100
Washington, DC 20009

Dear Mr. Cook:

Thank you for your letter of January 19, 2005, in which you expressed
concern about some of the accounts that have appeared in the news media
about the National Research Council's recent report, Health Implications
of Perchlorate Ingestion.

You are correct in pointing out that the committee's report did not
recommend a drinking-water concentration standard for perchlorate, as
some news accounts have regrettably stated or implied. As your letter
correctly stated, our committee's report presented an estimated daily
reference dose (RfD) of 0.0007 milligrams of perchlorate per kilogram of
body weight. The RfD is a maximum dose of perchlorate per kilogram of
body weight that the committee judged may be safely ingested by the most
sensitive individuals on a daily bases from all sources, including food
as well as drinking water.

The committee was constituted and charged to address scientific
questions, not public policy matters. The RfD recommendation in the
committee's report is based on the available scientific data and goes as
far as science alone can take us. Establishing a drinking-water
concentration standard will additional require making policy choices and
policy-based assumptions that go beyond science on matters such as water
consumption habits, body weights, relative contributions of perchlorate
from sources other than drinking water, the cost and feasibility of
water treatment technologies, and the risk levels deemed acceptable.

The National Research Council is preparing a report brief that we expect
to distribute widely and post on our web site in the near future to help
communicate the main findings of the report. Although we believe that
the report itself and the National Academies' January 10 news release
state the above points clearly, we are interested in disseminating the
report more broadly in a readily understandable form to all interested audiences.

Sincerely,

James J. Reisa
Director

***

January 19, 2005

Dr. James J. Reisa, Director
Board on Environmental Studies and Toxicology
National Academy of Science
500 Fifth St. NW
Washington, DC 20009

Dear Dr. Reisa:

On Jan. 10, the Academy's Committee to Assess the Health Implications of
Perchlorate Ingestion released a long-awaited report. Much of the news
media reported that the committee concluded that the chemical is
dramatically safer than was previously thought, and therefore regulatory
agencies and environmentalists have been overly concerned about its
presence in the tap water of millions of homes. 

As you know, this is a misrepresentation of what the report actually
said. The committee did not recommend a drinking water standard but a
daily reference dose (RfD), representing an amount of the chemical from
all sources that may be consumed safely per kilogram of body weight. Few
journalists understood the difference between an RfD and a drinking
water standard well enough to report that if the lower body weights of
infants (the population most at risk from perchlorate) and exposure from
sources other than drinking water are applied to the committee's
recommendation, the resulting drinking water standard is not
significantly different than the 1 ppb proposed by the state of
Massachusetts, the 6 ppb proposed by the state of California, or the
hypothetical 1 ppb derived from the EPA's 2002 risk assessment. 

Under California's Public Records Act, Environmental Working Group (EWG)
has obtained a copy of a Jan. 12 e-mail sent by committee chair Dr.
Richard T. Johnston to Dr. Bob Howd, chief of water toxicology for
California's Office of Environmental Health Hazard Assessment (OEHHA).
The e-mail indicates that Dr. Johnston and other panel members
recognized that many reporters got the story wrong and tried with
limited success to set the record straight: 

"We were also struck by the fact that many reporters made the
extrapolation to ppb, in spite of the fact that we pointed out in detail
that making the step to a drinking water standard was not our charge . .
. I also tried to emphasize [Jan  10] that our recommendation dealt with
a total dose from all sources, like a dose of medicine, and that this
should be corrected for the weight of the individual. When we saw how
often the press got it wrong, we worked hard [at a followup public
meeting Jan. 11] to correct this . . ."

Dr. Johnston's position was echoed by committee member Dr. Richard
Corley, in a Jan. 12 radio discussion with Bill Walker, EWG's vice
president for the West Coast., on KPCC-FM in Pasadena., Calif. Asked if
the committee's recommendation should be adjusted for body weight and
total exposure in converting it to a drinking water standard, Dr. Corley
replied: "Absolutely correct."

On the day the committee's report was released, EWG took a different
position than some environmental groups. We saw that applying additional
factors to the recommended RfD will yield a drinking water standard
close to those regulators have already proposed, and issued a press
release commending the report. We are gratified that Dr. Johnston's and
Dr. Corley's subsequent statements are in agreement with our position.
But we remain deeply concerned that the news reports have left many
Americans, including health officials and elected representatives, with
the mistaken impression that the committee gave perchlorate a clean bill
of health. 

Therefore, we are respectfully requesting that the Academy undertake a
more formal effort to correct these misperception, perhaps in the form
of a clarifying statement. Perchlorate polluters have already begun a
public relations and lobbying campaign to persuade the public, elected
officials and regulators that the Academy decided that higher levels of
perchlorate in drinking water are safe for even infants and nursing
mothers. If the record isn't set straight, we could end up with
standards that leave millions of people at risk - surely not the
committee's intent in producing the study. We thank you for your
attention to this important matter. We look forward to your response. If
you need any more information, please let me know. 

Sincerely,

Ken Cook  
President 
Environmental Working Group

***

[January 12, 2005 e-mail reply from Dr. Richard B. Johnston, chair of
the NAS perchlorate committee, to Robert A. Howd, Chief, Water
Toxicology Unit, Office of Environmental Health Hazard Assessment, Cal/EPA]

We were also struck by the fact that many reporters made the
extrapolation to ppb, in spite of the fact that we pointed out in detail
that making the step to a drinking water standard was not our charge or
intent, and that this was a public health policy decision that should be
made with understanding of the local consumption patterns, distribution,
etc. I also tried to emphasize on the phone conference Monday that our
recommendation dealt with a dose from all sources, like a dose of
medicine, and that this should be corrected for the weight of the
individual. When we saw how often the press got it wrong, we worked hard
yesterday to correct this on the phone/web public conference .
. . 
So why the reporting of 20 ppb? I think this was an attempt to relate it
back to the oft-cited 1 ppb figure that resulted in the commissioning of
the NAS study. [Reporters] simply used the same assumptions regarding
consumption that were used originally - 70 kg body weight, 80% of perc
intake coming from water, 2L/day consumption (as I recall). We never
evaluated or discussed these assumptions and certainly didn't mention
them in public. We definitely did assume that, if the same assumptions
were applied, a safe water content would be "about 20 ppb" (the
difference in RfD is actually about 23, but we resisted being that
exact). We based this conclusion primarily on the human data as a guide
to human effects, and it avoided modeling which we felt was too
arbitrary compared to the actual data. . . . 

Please let me try to be helpful if I can; I'm sure other committee
members feel the same way.

Dick Johnston

***

[January 12, 2005 e-mail from Robert A. Howd to Dr. Richard B. Johnston]

Dr. Johnston,

Congratulations on finalizing the evaluation of the US EPA perchlorate
risk assessment! I think your committee has done a fine job, and I
commend you all for it.

As the lead for the Cal/EPA Office of Environmental Health Hazard
Assessment group which developed the California Public Health Goal, I
admit to being a bit biased in my review of your conclusions, of course.
In monitoring the press responses to the NAS report, we have been struck
by how many of them noted that a drinking water level of 20 ppb would
result from the RfD of 0.0007 mg/kg-day. Our question to you is, do you
know why this has been so widely touted? We are aware that the committee
was not charged with the duty of recommending a safe drinking water
level, and did not do so, but is this a level which you personally, or
perhaps the committee as a whole, would support? 

We are still grappling with whether our Public Health Goal of 6 ppb
should be reconsidered, and are hoping that the committee's
deliberations might have provided more perspective on an appropriate
bottom line, which you would be willing to share with us.

Thanks for any help you can provide.
Robert A. Howd, Ph.D., Chief, Water Toxicology Unit
Office of Environmental Health Hazard Assessment, Cal/EPA
1515 Clay St., 16th floor, Oakland, CA 94612


-- 


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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