[CPEO-MEF] TCE standards

[Lenny Siegel <lsiegel@cpeo.org>]

The Environmental Health Committee of U.S. Science Advisory Board (SAB)
is expected soon to put finishing touches on its peer review of the
agency's August, 2001 public review draft of its Trichloroethylene [TCE]
Health Risk Assessment. The Committee has a public teleconference
scheduled for July 18, 2002.

According to the July 2, 2002 Defense Environmental Alert (DEA), the new
risk assessment could lower the generic cleanup goal for TCE to 1 part
per billion in groundwater from the current 5 parts per billion. DEA
reports, "An Air Force scientist at the SAB meeting argued, 'there is no
cancer risk at environmental exposure levels' and that ongoing efforts
to clean up to the current goal of 5 parts per billion (ppb) have been
challenging. The Air Force estimates that if EPA were to implement
standards based on the new risk review, cleanup requirements would drop
to 1 ppb at the 1,295 groundwater and 334 soil contaminated sites
managed by the Defense Department." (Note that a site is an individual
plume or hot spot in Defense parlance, not an entire installation or
property.) According to DEA, the Defense Department may ask the White
House Office of Management and Budget to review the EPA document "to
assure that the benefits and costs of the more stringent cleanups are
fully considered."

A new cleanup standard would trigger the review of a multitude of
existent cleanup plans, not only at Defense sites but other properties.
Its impact at those sites would be uncertain, however, since the common
5 ppb level is already an unreachable goal at many locations. A more
stringent level might have more impact at locations which are not being
addressed because the maximum detected concentration is below 5 ppb.

The reported Defense position, while understandable, fails to recognize
the way that the National Contingency Plan works. While official
standards are used to set remedial action objectives, the selection of
actual remedies is based upon the balancing of a number of factors,
including cost and practicality. That's when cost should be considered.
Health-based standards should be based upon science, not the difficulty
of implementation.

And the SAB panel seems to like EPA's science in the TCE risk
assessment, according to its June 18-19 minutes, downloadable from
http://www.epa.gov/science1/tcedft061802m.pdf, it agreed:

"The Agency should be commended for its groundbreaking work in the
following areas: children's issues; susceptibility cumulative risk; use
of modeling; explicitly recognizing/acknowledging uncertainties; use of
multiple endpoints for derivation of RfD [reference dose]; examination
of multiple modes of action; multiple metabolites."

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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