On Jul 23, 2025, at 10:01 AM, Jonathan Dannatt <jdannatt**At_Symbol_Here**udallas.edu> wrote:

Hey Jessica, 

Thank you. Your comments here are really helpful. I'm curious about what you've seen regarding solvent removal of DCM, for example, after a reaction it is pretty common to rotovap the reaction mixture to remove the solvent. 

Warmest regards, 

Jonathan 

On Wed, Jul 23, 2025 at 8:22 AM Jessica Martin <jmartin54321**At_Symbol_Here**gmail.com> wrote:

I’ll add to what James said here. As we have been doing monitoring at my institution, a few things have come up regarding handling that it is good to make sure you are watching for. 

While we did have researchers who were “using DCM in the hood”, they were also doing things like (i) filling a smaller container from a larger container of DCM outside of hoods, (ii) even if the filling was happening inside of a hood, the researcher would then walk the open beaker over to a different hood (hence outside of the hood), (iii) we would have researchers walk DCM over to a waste container that wasn’t in a hood.

While none of these practices in isolation gave us problematic reads, added together they start to look like you are getting close to limits of exposure - or tipping just over. So as you are working through best practices with researchers, just be mindful of these smaller things that some folks may not think of when they think about “working with DCM in the hood.” With some minor adjustments to some of the practices above, we were able to get DCM monitoring results well under the limits.

Jessica A. Martin, Ph.D.

323-327-3974

jmartin54321**At_Symbol_Here**gmail.com

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On Jul 22, 2025, at 4:28 PM, James Saccardo <James.Saccardo**At_Symbol_Here**CSI.CUNY.EDU> wrote:

John,

Waste is the least of your worries. You CHP should state no procurement without prior approval. Your CHP can also refer to MeCl  (workplace chemical protection plan) WCPP if you have one.

Anyone using methylene chloride must perform initial monitoring to determine employee exposure levels. If you do not exceed the 2ppm level 8 hr TWA, you don’t need to have a WCPP, but is prudent to have one that lays out periodic monitoring requirements, storage and use locations.

If using in a laboratory fume hood correctly, I can’t imagine exceeding the limits of the TSCA rule

 

There are a few other caveats, like demarking the work areas, restricted access when in use, but anyone possessing and using MeCl must follow the EPA TSCA 2024 final rule.

 

As for your initial question, you should check with your TSDF end facility and see what their requirements are for waste containing MeCl. Anyone handing waste may also need to be monitored for exposure levels.

 

Finally, some have been using 1,2-dichloroethne as an alternative solvent but are not as pleased with the performance in their work ups as with MeCl. This may be good for commerce, but it hurts basic research. Please let the list know if you have any good MeCl monitoring techniques, vendors, or alternatives to MeCl.

Best,

James

 

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of Jonathan Dannatt
Sent: Monday, July 21, 2025 10:43 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: [DCHAS-L] How should DCM be handled in a chemical hygiene plan?

 

* This email originates from a sender outside of CUNY. Verify the sender before replying or clicking on links and attachments. *

Hey all,  

 

We are updating our chemical hygiene plan and were wondering if you all could provide some guidance on how DCM should be written in the plan. We have a category for halogenated wastes, but with the new rules do we need to separate halogenated waste from DCM? Do we need to include more language about measuring exposure, etc? 

 

Thank you for any help you can provide. 

 

Warmest regards, 

Jonathan

 

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Jonathan Dannatt, Ph.D.

Associate Professor

Department of Chemistry

University of Dallas

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