2013 CPEO Brownfields List Archive

From: Lenny Siegel <lsiegel@cpeo.org>
Date: Fri, 4 Oct 2013 11:36:03 -0700 (PDT)
Reply: cpeo-brownfields
Subject: [CPEO-BIF] New York lowers PCE air guideline
 
In September 2013 the New York State Department of Health (NYS DOH) finally lowered its inhalation guideline for tetracholoroethene (PCE or perc), but the level is not as low as some of us had hoped. See www.health.ny.gov/environmental/chemicals/tetrachloroethene/index.htm for the official fact sheet.

The new guideline is 30 micrograms per cubic meter (ug/m3) or 4.4 parts per billion by volume (ppbv), replacing the 100 ug/m3 value established in 1997. The new value is not as low as the number (4 ug/ m3) that New York says EPA gives for a one-in-a-million excess cancer risk (based upon continuous lifetime exposure), and it is far from California's .41 ug/m3 threshold.

The "ambient air" guideline is not a bright line. "NYSDOH recommends that reasonable and practical actions should be taken to reduce PERC exposure whenever air levels are above background." Furthermore, NYSDOH's action matrix for PCE vapor intrusion takes into account soil gas levels as well as indoor air levels. Still, the new guideline appears to be based on residential (continuous) exposures, so the guideline for workplaces or schools impacted by subsurface PCE sources could be five times higher.

The PCE air guideline is particularly important for New York City, where only one groundwater area supplies drinking water. The city is dotted with "rogue" PCE plumes from current and former dry-cleaning establishments. The plumes present a risk of vapor intrusion, but with the guideline remaining so high it's not clear how many of them will be addressed with mitigation (such as substructure depressurization) or cleanup.

--

Lenny Siegel
Executive Director, Center for Public Environmental Oversight
a project of the Pacific Studies Center
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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