From: Monona Rossol <actsnyc**At_Symbol_Here**>
Subject: Re: [DCHAS-L] Benchtop Methylene Chloride Use in Undergraduate OChem labs
Date: Tue, 18 Nov 2014 09:02:58 -0500
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: 8D1D14F7E391FE5-1310-4192A**At_Symbol_Here**
In-Reply-To <314476593.1937145.1416286464125.JavaMail.zimbra**At_Symbol_Here**>

To answer definitively, you would need to know the loss by evaporation of the methylene chloride during the class and the dilution rate for the room.  But as someone who does this kind of stuff for art, I would guess, that with a TLV of 50 ppm (and the OSHA PEL of 25), it is not likely you have a dilution rate 100% to the outside that would accommodate this solvent without noticing a breeze. 
Monona Rossol, M.S., M.F.A., Industrial Hygienist
President:  Arts, Crafts & Theater Safety, Inc.
Safety Officer: Local USA829, IATSE
181 Thompson St., #23
New York, NY 10012     212-777-0062

-----Original Message-----
From: drsamples <drsamples**At_Symbol_Here**COMCAST.NET>
Sent: Tue, Nov 18, 2014 6:26 am
Subject: Re: [DCHAS-L] Benchtop Methylene Chloride Use in Undergraduate OChem labs

Dear All,

I have a question for anyone involved in undergraduate Organic Chemistry labs.

Methylene chloride is listed as a recognized carcinogen in California, and it is a B2 probable human carcinogen. As you all know, it is a volatile liquid commonly used in undergraduate Organic Chemistry labs as the organic solvent in liquid-liquid extractions using a separatory funnel. As many OChem labs lack adequate fume hoods, many colleges do these extractions at the bench, and so are venting methylene chloride in the general laboratory. Generally, these are not microscale extractions, but are regular lab scale with a 250 or 500 mL sep funnel.

It is a volatile probable human carcinogen and thus I believe that it should be handled in the fume hood and the extraction should also be done in a fume hood. Do you agree or disagree? If you agree, have you been successful in changing how your department handles methylene chloride in undergrad labs, and if so, how did you successfully argue your case to handle it in fume hoods?


Marjorie Samples
Chemistry Professor
Los Rios Community College District

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