[CPEO-MEF] Perchlorate exposures from food

[Lenny Siegel <lsiegel@cpeo.org>]

At the Symposium on Perchlorate Exposures from Food and the Environment
last Thursday, Ben Blount of the Centers for Disease Control presented
the results of his studies of perchlorate in the urine of a convenience
population in Atlanta, where the concentration of perchlorate in
drinking water is about .1 or .2 parts per billion (ppb). As previously
reported in the Riverside Press Enterprise (January 25, 2006), all of
the urine samples had elevated perchlorate levels.

The minimum was .66 ppb, the maximum was 21 ppb, and the geometric mean
was 3.7 ppb. The health implications, he pointed out, depend upon which
level is considered safe.

Blount also presented unpublished data comparing subjects who ate more
dairy and vegetable products than others, finding that the
dairy-vegetable group had significantly higher perchlorate levels.

This has significant implications:

1. Since people, at least in some parts of the country, appear to ingest
more perchlorate in food than drinking water, the drinking water
standard for perchlorate should be based on a high relative source
contribution. Even if one uses U.S. EPA's high guidance level of 24.5
ppb, the maximum contaminant level, if ever promulgated, could be as low
as 5 ppb.

2. Long-term efforts to protect the public from perchlorate exposure
will have to go beyond point sources and the drinking water pathway to
consider other potential pathways.

3. Much more research needs to be done to determine how perchlorate
enters the food supply. How much is from irrigation water? How much is
from agricultural chemicals, such as Chilean fertilizer? How much is
precipitated out of thin air, and how much of that is the result of
anthropogenic releases of chlorine and chlorine compounds?

Lenny

-- 


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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