Re: [CPEO-BIF] "Chemical vapors contaminate hundreds of properties across Minnesota"

["Laurent C. Levy" <LLevy@gradientcorp.com>]

A couple of errors in this article when writing the following statement:

"For instance, in Minnesota, the new long-term health limit for fumes from dry-cleaning solvents has dropped 10-fold, from 20 parts per billion to an infinitesimal 2 parts per billion, said Jim Kelly, environmental health manager at the Minnesota Department of Health. That's because long-term exposure to even very low concentrations can result in cancer, as well as fetal development problems for pregnant women."

First, a unit error.  It should be micrograms per cubic meter and not parts per billion. The ppb to ug/m3 conversion is compound specific (molar weight dependent) when contemplating indoor air or soil gas concentrations (for PCE, 1 ppb = 6.78 ug/m3; for TCE 1 ppb = 5.37 ug/m3). It is correct, however, that MN dropped the residential indoor air screening level for PCE from 20 ug/m3 to 3.4 ug/m3 (or 2 ug/m3 depending on where you look). 

Second, the fetal development relates to TCE, which unlike PCE is not a common dry-cleaning solvent. It is my understanding that the drop in the PCE screening level is due to MN deciding to follow Calif. and Mass. approach and consider the leukemia endpoint (http://www.health.state.mn.us/divs/eh/risk/guidance/air/tetrachloroethylene.html) rather than the liver cancer endpoint, which EPA and many other States use and results in a larger screening level for PCE (basically, by one order of magnitude). The next few years will tell us whether other States decide to follow suit. 

Laurent
---
Laurent C. Levy, Ph.D., P.E. | Senior Project Manager 
617-395-5566 | llevy@gradientcorp.com
http://vapor-intrusion.blogspot.com/   
 

Gradient | 20 University Road | Cambridge, MA 02138 | 617-395-5000 | www.gradientcorp.com

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-----Original Message-----
From: Brownfields [mailto:brownfields-bounces@lists.cpeo.org] On Behalf Of Lenny Siegel
Sent: Sunday, February 26, 2017 12:58 AM
To: Brownfields Internet Forum
Subject: [CPEO-BIF] "Chemical vapors contaminate hundreds of properties across Minnesota"

Silent but toxic, chemical vapors contaminate hundreds of properties across Minnesota

By Josephine Marcotty
Minneapolis Star Tribune (MN)
February 25, 2017 

You can't see it. You can't smell it.

But toxic vapor rising from soils contaminated decades ago by industrial solvents is creating new and expensive headaches for property owners across Minnesota.

Pollution officials have identified hundreds of sites across the state that are contaminated by "vapor intrusion," and this month they began rolling out a new set of rules requiring property owners to test for vapors and address them before transferring property.

Even as state officials scramble to understand the scope of the problem, business owners are facing millions of dollars in new costs to make their buildings - and their neighbors' buildings - safe from the carcinogenic fumes that collect inside from widely used solvents long since discarded.

...

For the entire article, see
http://m.startribune.com/silent-but-toxic-chemical-vapors-contaminate-hundreds-of-properties-across-minnesota/414787933/?section=local

--

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
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org

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