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November 13, 2009
It's a Gas
A search of EnviroReporter.com for the toxic solvent trichloroethylene (TCE) will yield no less than 31 pages and posts. There’s a reason for that: TCE is one of the most pervasive toxins plaguing California and over a dozen other states.

But a breath of fresh air may be in store. On November 3, the U.S. Environmental Protection Agency released the External Review Draft of its Toxicological Review of Trichloroethylene for public review and comment.

The agency has taken the extraordinary step of recommending that levels of TCE permeating indoor air should be cut by over four times its current goal. The action, which has vast implications especially in Southern California, is in response to the challenge this contaminant poses to public and environment, according to the agency’s website:

The draft Toxicological Review of Trichloroethylene (TCE) provides scientific support and rationale for the hazard and dose-response assessment pertaining to chronic exposure to TCE. TCE is a chlorinated solvent that has been widely used as a metal degreaser, as a chemical intermediate and extractant, and as a component of some consumer products. TCE is designated as a Hazardous Air Pollutant, is a common groundwater contaminant, and has been found at more than 1,500 hazardous waste sites. TCE enters the atmosphere from vapor degreasing operations or volatilization from contaminated soils, surface waters via direct discharges, and groundwater through leaching from disposal operations and hazardous waste sites. In addition, TCE can be released to indoor air from the use of TCE-containing consumer products, volatilization from water supplies, and vapor intrusion through walls and floors from contaminated soil and groundwater.

That means gunk in the groundwater can rise through the soil in gaseous form and collect in above-ground structures like homes, schools and churches. If you’re living over a TCE plume, like inhabitants in Scottsdale Arizona who don’t have specialized ventilation systems, it might be a good idea to keep the windows open.

Drinking small amounts of TCE for long periods may cause impaired immune system function, liver and kidney damage and impair fetal development in pregnant women. Larger drinking doses may cause liver damage, nausea, impaired heart function, unconsciousness or death. Breathing small amounts may cause dizziness, lung irritation, headaches, difficulty concentrating and poor coordination. Inhaling large amounts of TCE may cause unconsciousness, impaired heart function and death.

The TCE exposure level associated with a one-in-a-million excess lifetime cancer risk, in a round-the-clock residential scenario is being lowered to .25 micrograms per cubic meter, or ug/m3. It may be even lower adjusting for childhood kidney cancer, just .20 ug/m3. Currently, EPA Region 9, based in San Francisco, uses 1.0 ug/m3 based upon state EPA research but California uses the higher level of 1.2 ug/m3.

If the new rule is finalized, it will become the “indoor air action level” for vapor intrusion response in many areas for environmental agencies. The .25 ug/m3 level is close to the amount of TCE in the air of America’s metropolitan areas, called the ambient outdoor air concentration. Where the one-in-a-million public health goal is in effect, mitigation would be required anywhere TCE levels are above background in homes and schools.

“If adopted, the proposed new toxicity value for TCE should drive the re-opening of site environmental decisions wherever indoor air contamination levels have been found to be barely acceptable,” Lenny Siegel tells EnviroReporter.com.

Siegel is the director of the Mountain View, California-based Center for Public Environmental Oversight, or CPEO. The group encourages public participation in decisions related to Superfund and Brownfield sites across the nation and has been ringing the alarm bell about TCE for years.

“In fact, mitigation (substructure depressurization) should be built into any structure where indoor TCE levels exceed outdoor levels, or any site which has serious TCE contamination remaining in shallow groundwater,” says Siegel.

In November, Siegel published a nine-page, 2.1 megabyte document entitled “A Stakeholder’s Guide to Vapor Intrusion” that he describes this way:

Vapor intrusion refers to the migration of toxic vapors from the subsurface – that is, soil or groundwater – into homes, schools, and other overlying buildings. Though many substances, such as petroleum hydrocarbons and even elemental mercury, can intrude into buildings, sites that require a response usually contain chlorinated solvents – that is, volatile organic compounds (VOCs) such as trichloroethylene (TCE) and tetracholoroethylene (also known as perchloroethylene or PCE). TCE was widely used as a solvent in industries such as aerospace and electronics, but in recent years a relatively small number of businesses, primarily in metals processing, continue to use it. It is still found in consumer products such as gun cleaner and plastic cement. PCE is still widely used in dry-cleaning and automotive servicing. Toxic compounds found in petroleum products, such as benzene, toluene, ethylbenzene, and xylene (BTEX), may also pose a vapor intrusion risk, but they tend to pose less of a risk because they normally degrade near the ground surface as they come into contact with atmospheric oxygen.

While individual scientists and some states, such as Massachusetts and Colorado, have been addressing vapor intrusion since the since the 1990s, vapor intrusion started to become a standard part of contaminated-site response in 2001, when U.S. EPA’s Resource Conservation and Recovery Act program stipulated such an assessment for all Environmental Indicator human health decisions. In early 2002, the Denver Post brought national attention to the problem with a landmark series on vapor intrusion. Since then environmental regulatory agencies across the country – U.S. EPA and most states – have developed technical and policy guidance for investigating and mitigating toxic gas vapors. Thousands of officials and consultants attend frequent conferences and workshops on the subject. Vapor intrusion responses are often major local news stories. But many Americans who are potentially exposed via the vapor intrusion pathway do not know about it, and many who know about it do not understand the many complexities involved in assessing and responding to vapor intrusion.

The former Rocketdyne lab in the Simi Hills has 800,000 gallons of the goo in its spreading groundwater which, if currently-configured remediation systems were turned on, would take 80,000 years to suck up and clean.

An eastern chunk of the San Fernando Valley is a Superfund site in part because of TCE, a plume courtesy of the old Lockheed plant in Burbank that is spreading towards the Los Angeles River which is about to have $2 billion dropped on it to be “greened” by the city of LA.

Revelations of trichlorethylene’s increasing toxicity, and its fouling of the Santa Susana Field Laboratory’s groundwater, helped stop the development of Ahmanson Ranch in 2003. Our piece “Air Apparent” broke that story in the Ventura County Reporter. The 17-year-old project collapsed later that year.

The ranch was sold to the state in 2003 for open space by former banking giant Washington Mutual for $150 million, a pittance for a project worth $2 billion. In 2008, “WaMu” collapsed in the largest bank failure in U.S. history.

Even local history aside, developers, including municipal ones, shouldn’t take the threat of TCE lightly. The solvent, along with its by-product tetrachloroethylene (PCE), present a very real threat to structures already standing in Southern California.

In an upcoming investigative series EnviroReporter.com will expose just how extensive this pervasive problem already is in the most unlikely of places in the San Fernando Valley. Stay tuned and we’ll leave the window open for you.

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