In This Issue:
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Colorado Issues Draft Indoor Air
Guidance |
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San Diego County adds Naphthalene to
Vapor Risk 2000 |
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Colorado Finalizes New TCE Action Levels |
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Oregon Screening Model for Heating Oil
Sites |
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Information Source on Household Products |
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EPA Issues Final Report on the
Neurotoxicity of PCE |
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The Importance of Background Evaluations |
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Featured Links:
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Colorado Issues Draft Indoor Air Guidance
The Colorado Department of Public Health and
Environment (CDPHE) has issues draft Indoor
Air Guidance for public comment. The draft
guidance is intended to result in more
consistent approaches to vapor intrusion
evaluations and is based on CDPHE experience
at a number of vapor intrusion sites. While
the guidance emphasizes flexibility and line
of evidence approaches, it states a
preference for indoor air sampling. Unlike
the EPA vapor intrusion guidance, CDPHE's
draft guidance includes procedures for
evaluating the extent of impacts and
mitigation. CDPHE generally defers to OSHA
PELs in occupational settings where workers
have "voluntarily accepted the known risks
associated with exposure". CDPHE will
consider comments received between November
15 and December 31, 2004.
San Diego County adds Naphthalene to Vapor
Risk 2000
San Diego County has revised its Vapor Risk
2000 model to include the new California
slope factor for Naphthalene (August 2004).
Because "naphthalene is present in all
petroleum fuels", San Diego County is now
requiring analysis for naphthalene at fuel
release sites. The following website
provides links to the San Diego County Vapor
Risk 2000 model, the California Office of
Environmental Health Hazard Assessment (OEHHA)
cancer slope factor for naphthalene, and
other websites with information on
naphthalene.
Colorado Finalizes New TCE Action Levels
On August 20, 2004 the Colorado Department
of Public Health and the Environment (CDPHE)
announced its adoption of an interim policy
regarding TCE in indoor air. This policy
requires mitigation if indoor air
concentrations of TCE exceed 1.6 ug/m3,
based on a 10-4 excess cancer risk level and
EPA's provisional TCE slope factor. The
policy also requires further study when a
concentration between 1.6 and 0.8 ug/m3 is
measured in indoor air. Mitigation is not
required if a lines of evidence evaluation
demonstrates that the TCE is due to
background sources. Although mitigation and
monitoring are not typically required at TCE
concentrations below 0.8 ug/m3, a no further
action approval requires a demonstration
that TCE concentrations are below 0.016 ug/m3
or background, if higher (go to
www.envirogroup.com/publications.htm for two
papers presenting background TCE data). The
new TCE policy, including CDPHE's general
policy on use of toxicity values, can be
found at the link below. CDPHE's response to
public comments on the proposed TCE action
levels is also provided at the same site.
Oregon Screening Model for Heating Oil Sites
The Oregon DEQ Heating Oil Tank program has
developed a spreadsheet model that estimates
site-specific screening levels for
volatilization from soil to indoor air at
heating oil tank sites. The model is
"offered for public use without guarantees
or support by the Department." DEQ also
states that it "may decide to use risk-based
screening levels other than those generated
by this spreadsheet."
Information Source on Household Products
The National Library of Medicine has a
database with information on common
household products. The database includes
material safety data sheets, which sometimes
identify the principal ingredients in the
products. The database may be useful in
investigating background sources of indoor
air contaminants.
EPA Issues Final Report on the Neurotoxicity
of PCE
In July EPA released the final report
“Summary Report of the Peer Review Workshop
on the Neurotoxicity of Tetrachloroethylene
Discussion Report”. This report can be found
at:
The Importance of Background Evaluations
EPA's provisional slope factors for TCE can
result in very low indoor air target levels,
as found in the Region 3 RBC tables (0.016
ug/m3), the draft EPA subsurface vapor
intrusion guidance (0.022 ug/m3), and in
many state programs. Unfortunately, recent
studies (go to link below) have shown that
background levels of TCE in residential
homes are much higher than these target
levels, with median or mean values of about
0.15 ug/m3 and 95 percentile concentrations
of 0.7 ug/m3. We have measured values in the
thousands of ug/m3 range in some homes
(e.g., due to gun cleaner use). Therefore,
it is critical that agencies and responsible
parties recognize the existance of
background sources and provide processes
that allow background to be considered when
setting action levels and mitigation
performance standards. Two papers providing
recent data on background levels of TCE and
other solvents in residential settings are
available on the link below.
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