[CPEO-MEF] perchlorate calculations

[Lenny Siegel <lsiegel@cpeo.org>]

Perchlorate report doesn't dispel controversy



REBECCA RENNER
Environmental Science & Technology Online News - Science News
January 19, 2005 

Perchlorate is not as hazardous as U.S. EPA scientists estimated, but it
is more harmful than many perchlorate manufacturers have suggested, says
a National Academy of Sciences (NAS) committee in a long-awaited report
released on January 10.

The safe dose recommended by the committee, 0.7 micrograms per kilogram
of a person's body weight per day (µg/kg-day), is 23 times higher than
EPA's draft reference dose but at least 7 times lower than perchlorate
industry groups? recommendations. The report, however, is unlikely to
dispel controversy about safe levels of perchlorate in drinking water
because calculating such levels involves additional information about
exposure sources as well as choices about whom to protect, according to
Alan Roberson, regulatory affairs director at the American Water Works
Association in Washington, D.C.

Possible perchlorate standards vary according to food, drink, and body weight
The U.S. National Academy of Sciences (NAS) has recommended a reference
dose of 0.7 micrograms per kilogram per day. To convert this dose into a
drinking-water standard, regulators will have to determine or estimate
how much perchlorate exposure comes from the food and water a person
consumes per day, based on their body weight. The U.S. EPA's default
assumptions are a 70-kilogram male who drinks 2 liters of water per day
and gets 80% of the dose through water, but regulators can use other
numbers. California's proposed drinking-water standard of 6 pp. assumes
that water contributes 60% of exposure.

...

For the entire article, see
http://pubs.acs.org/subscribe/journals/esthag-w/2005/jan/science/rr_perchloratereport.html


-- 


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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