[CPEO-BIF] Vapor Intrusion Testimony

[Lenny Siegel <lsiegel@cpeo.org>]

[This is my prepared testimony for today's (November 15, 2004) New York 
State Assembly hearing on Vapor Intrusion. For a formatted version, go 
to http://www.cpeo.org/pubs/NYTCETestimony.doc. - LS.]

VAPOR INTRUSION: A COMPLETED PATHWAY THAT DESERVES A PRECAUTIONARY APPROACH

Lenny Siegel
November, 2004


The surfacing of toxic vapor into our communities is one of the nation's 
most significant emerging environmental health issues. The New York 
State Department of Environmental Conservation and the New York State 
Department of Health should be praised for their pioneering efforts in 
this area. However, because vapor intrusion, where it occurs, is a 
completed pathway, there is a need to establish a more rigorous, 
comprehensive, precautionary response.

My name is Lenny Siegel. As Executive Director of the Center for Public 
Environmental Oversight, I work with community groups across the nation 
on vapor intrusion and other environmental health threats. As a resident 
of Mountain View, California, site of at least four ongoing vapor 
intrusion investigations, I have taken a crash course on the issue over 
the past two years.

Here is some of what I have learned.

Don't treat people like guinea pigs.

People who live and work above soil and water contaminated with 
trichloroethylene (TCE), perchloroethylene (PCE), and other hazardous 
volatile chemicals are continuously exposed. It appears, at most of 
these sites, that the exposures have been occurring for decades. While 
it is usually possible to replace contaminated drinking water with water 
from alternate sources, it's much harder to replace the air we breathe.

TCE, once the universal solvent, is found in at least 852 of U.S. EPA's 
nearly 1,500 "Superfund" National Priorities List sites and thousands of 
other properties. Liquid TCE sinks and spreads within ground and surface 
water, yet the chemical also vaporizes and rises to the surface. Many 
TCE plumes in groundwater are several miles long. Though not found in 
nature, "background" levels of TCE are detectable in many urban airsheds.

In August 2001, EPA released a draft toxicity assessment for TCE. In 
summary, it found that children were more susceptible to TCE exposure 
than adults, and that TCE was five to sixty-five times more toxic than 
previously believed. EPA's Science Advisory Board peer review praised 
the "groundbreaking" assessment, finding:

The Board advises the Agency to move ahead to revise and complete this 
important assessment. The assessment addresses a chemical, 
trichloroethylene (TCE), significant for being a nearly ubiquitous 
environmental contaminant in both air and water, being a common 
contaminant at Superfund sites, and because it is "listed" in many 
Federal statutes and regulations. The draft assessment is also important 
because it sets new precedents for risk assessment at EPA. We believe 
the draft assessment is a good starting point for completing the risk 
assessment of TCE. The Panel commends the Agency for its effort and 
advises it to proceed to revise and finalize the draft assessment as 
quickly as it can address the advice provided in this report. (See 
http://www.epa.gov/sab/pdf/ehc03002.pdf)

Based upon the draft assessment, most EPA regions have adopted a new 
"provisional" air screening level for residential or unrestricted 
exposure scenarios, corresponding to one excess lifetime (30-year) 
cancer among a million people, of .017 micrograms per cubic meter. This 
is known in EPA's Region 9 as the provisional preliminary remediation 
goal for residential or unrestricted scenarios. Though this low number 
cannot currently be used as the basis for enforcement orders, it still 
guides investigations in my California community.

However, responsible parties -  the original polluters or their 
corporate descendants - are challenging EPA's draft toxicity assessment 
and the resulting lower health standards. In particular, the Defense 
Departments, which may face additional cleanup costs of hundreds of 
millions or even billions of dollars if the new risk findings hold, has 
elevated the question within the executive branch. The question of 
whether published studies really show that TCE is more harmful to 
children and other sensitive populations has been sent to the National 
Academy of Sciences for re-review, and U.S. EPA will not promulgate a 
new standard for years, if ever.

To my knowledge, while aggressively responding to high levels of TCE in 
indoor air - above 5 micrograms per cubic meter - New York has no clear 
plan for when and how to respond at lower concentrations. It has not 
made a clear case for an action level well above what we're using in 
Region 9.

I am not a toxicologist, and I recognize that reputable toxicologists 
argue about the level of risk that TCE poses to people who are exposed. 
However, I think it is important that policy-makers take a protective, 
or precautionary approach. That is, those people from TCE-impacted 
communities should not be treated as lab animals while we all await the 
results of the scientific debate. The Region 9 provisional standard was 
not pulled our of the air. It's based upon sound, peer-reviewed science, 
and that should be good enough to guide vapor intrusion investigations 
at this time.

Consider all sources, pathways, and receptors.

Vapor intrusion is usually viewed as the spread of toxic fumes from 
underlying groundwater or soil directly into people's homes or other 
structures. That is often the most acute problem, but the risks are much 
broader. There may be chemicals in the air from other sources. Even 
though those pollutants may be subject to the authority of other 
agencies, the public should be made aware of those risks, and those 
agencies should be brought into the investigations.

More important, contamination from major groundwater plumes may escape 
over a large area, elevating ambient concentrations above the screening 
level. In my community, TCE was found in outdoor air at a local 
elementary school - sampled originally as a reference location. Some 
responsible parties call this a "background" level, as if TCE were a 
naturally occurring substance. I believe, however, that 
neighborhood-wide toxic clouds, which vary with atmospheric conditions, 
are still the responsibility of the polluters. The contamination levels 
outdoors are generally lower than indoor contamination where there is a 
direct pathway, but larger numbers of people may be exposed.

To properly assess the human health risk, therefore, investigations 
should be based upon conceptual site models that consider all sources, 
pathways, and receptors. This means sampling to identify outdoor toxic 
clouds, and correlating those measurements with meteorological data. It 
means that venting and unscrubbed air-stripping, both of which simply 
move contamination into the air, should not necessarily be viewed as 
long-term solutions.

Furthermore, in deciding which areas to investigate - such as at which 
homes to sample indoor air or soil gas - it's important again to take a 
precautionary approach. The science for  estimating indoor air pollution 
is still immature. I doesn't account for preferential pathways. It 
doesn't account for uncertainty in the horizontal extent in 
contamination. In Mountain View, both factors have emerged.

Remediate. Don't just mitigate.

The presence of toxic vapors in people's homes, other structures, and 
the outdoor air is both a problem in itself and a sign of broader 
challenges. It makes sense, as New York has done, to act quickly to 
reduce the worst exposures. But it's also essential to deal with the 
long-term problem as well, for at least three reasons:

First, it is difficult to ensure that mitigation measures will remain 
effective in the long run.

Second, without the accelerated remediation of shallow groundwater or 
soil, there is no timely way to reduce outdoor exposures.

And third, it is difficult to redevelop or otherwise reuse 
vapor-impacted properties, and in most local economies current, innocent 
owners of such property may experience lowered property values. The 
cause isn't publicity or even the identification of the sites by 
regulatory agencies; it's the contamination itself.

Groundwater extraction systems - known as pump-and-treat - may have been 
the only remediation game in town five years ago, but now there are 
numerous alternatives that can protect more quickly against vapor 
intrusion, restore groundwater resources, and actually reduce the 
life-cycle costs of remediation.

New York State officials have told me that they agree that additional or 
more rapid cleanup is the logical response to vapor intrusion. Since, in 
promoting this approach, they may be going up against powerful economic 
and political forces, they need all the political help they can get.

I propose the following.

1.  That environmental regulators use .017 micrograms per cubic meter - 
as a screening level in their investigations. Laboratory analysis should 
strive for this detection limit. Exposures at this level should be 
measured. Sources of such exposures should be identified. Additional or 
accelerated remediation should be evaluated wherever ambient - that is, 
outdoor-sampling finds repeated readings above the screening level.

2.  Soil and groundwater cleanup goals should consider more than the 
ingestion pathway - that is, drinking water and eating soil. They should 
also be strong enough to protect the air.

3.  Mitigation - such as sub-slab depressurization systems - should be 
considered wherever sampling shows TCE exposures above .17 micrograms 
per cubic meter, ten times the screening level.

4.  Development proposals at potential vapor intrusion sites should be 
denied wherever soil gas studies suggest that indoor air concentrations, 
after construction, may exceed the screening level. Housing and other 
sensitive uses should only be approved where A) it does not interfere 
with accelerated remediation, B) construction measures, such as 
impermeable slabs, are used to prevent vapor intrusion, C) lasting 
institutional controls can be imposed to ensure long-term monitoring as 
well as the implementation of contingency plans should engineering 
controls fail, and D) prospective buyers, renters, and other users of 
the property are warned of potential risks in time to make informed 
decisions.

5.  The cleanup remedy decision should be reopened - that is, 
reconsidered - at any site where vapor intrusion is recognized after the 
remedy selection process has been completed. At many sites, such as the 
sites in my community, the remedies are generally protective of our 
drinking water resources. But when those plans were adopted, there was 
no recognition of the vapor intrusion pathway.

Across the United States, environmental and health agencies, as well as 
scientists from government, academia, and industry, are working hard to 
understand both the mechanisms of vapor intrusion and the toxicity of 
the most common contaminants. Each new vapor intrusion site isn't just a 
mitigation or cleanup project. It's a research site. That's OK in 
itself, as long as policy-makers make it clear that protecting public 
health, with a clear margin of safety, is the primary goal. New York, as 
one of the first states to take on the vapor intrusion challenge, has 
the opportunity to set a positive, protective precedent.

--
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
http://www.cpeo.org



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