DCHAS-L Archives, May 9, 2023 - Re: [DCHAS-L] EPA ban of methylene chloride

Thanks for bringing this up! Someone really needs to address this issue and bring some balance into what appears to be a(nother) knee-jerk set of regulations. I will jump in and volunteer to join further discussions.

Several thoughts:

I am surprised that industry has not reacted more to this (but perhaps they have, I just don't know it).

Chlorinated solvents play an important role: deuterated chloroform is the go-to solvent for nmr, and how many times have researchers encountered samples that are only soluble in chlorinated solvents? I have material right now that is insoluble in water, hexane, methanol.... yet chlorinated solvents work just fine.

And yet, carbon tet is effectively banned, and rules for chloroform get ever stricter. As an example from undergraduate lab education, I taught a course for many years that had a peptide synthesis: the driving force for coupling was simple: water was removed by azeotropic distillation with carbon tet. H&S simply said "replace." So I tried to substitute toluene, which also forms an azeotrope with water BUT it didn't work because the amino acid components didn't dissolve. After many further failures, in the end I replaced the lab with a "modern" peptide synthesis BUT note that it used DCC, with all the issues of sensitivity, etc. that this alternative creates. Moral is that we need to be careful about making things worse with overly simplistic thinking.

Some years back, I was outside my academic office, and close to the elevator. I watched as a student exited the elevator with a case of four 4 Litre bottles of DCM, caught one castor in the elevator door track, and all 4 bottles fell off the cart, smashed and 16 Litres washed across the floor. Evaporation was of course fast, and the vapour was overwhelming for a while, HOWEVER, no-one fainted or suffered any further problems. This is not to suggest that this was an event that could be ignored, nor to belittle the unfortunate stories where DCM caused injury or death. Only to point out that rules that work in some industries may not work in all, and that many safety regulations seem to fit poorly into the academic setting.

I worry that the present proposal for DCM will only be another example of an overly simplistic approach to banning a compound that clearly is essential at least in academia and which can be used without hazard. I would rather consider banning the application, not the chemical itself.

I look forward to an interesting discussion!

Best wishes,

Paul Harrison, B.A. Hons. (Oxon), Ph.D.

Associate Professor

Chemistry & Chemical Biology

Dept. of Chemistry & Chemical Biology
ABB-156
McMaster University
1280 Main St. West.
Hamilton, ON L8S 4M1

location: ABB-418

phone: (905) 525-9140 x 27290

email: pharriso**At_Symbol_Here**mcmaster.ca

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> on behalf of Jennifer Mattler Guzman <jmattler**At_Symbol_Here**STANFORD.EDU>
Sent: Thursday, May 4, 2023 12:00 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Subject: Re: [DCHAS-L] EPA ban of methylene chloride

Hi,

I’m interested in talking to members here about the proposed regulation, its impact to universities, and commenting on behalf of DCHAS (we may need approval from ACS, can the board members comment?). If others are interested, reply here and we can try to organize a sidebar conversation on zoom.

Admittedly I haven’t read the Risk Evaluation that this regulation is based on, but I do question the necessity of requiring SCBAs when exposures exceed 2 ppm as an 8-hour TWA. I suspect they added that stringent of PPE to effectively ban DCM at exempt employers because frankly, an SCBA is a non-starter. I sincerely hope our fume hoods control below that level, but am not 100% sure all the time.

Jennifer

Jennifer Mattler Guzman, CIH, M.S., M.S. (she/her)
Industrial Hygienist/Chemical Hygiene Officer
Environmental Health and Safety
Stanford University
650.723.0183

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of Christine Rogers
Sent: Wednesday, May 3, 2023 8:07 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: [DCHAS-L] EPA ban of methylene chloride

Just alerting folks to the publication in the Federal Register of a proposed rule to ban the manufacture and use of methylene chloride (dichloromethane). Here is the link https://www.govinfo.gov/content/pkg/FR-2023-05-03/pdf/2023-09184.pdf?utm_source=federalregister.gov&utm_medium=email&utm_campaign=subscription+mailing+list

It seems that research at universities might fall into the category of “Industrial and Commercial Use as a Laboratory Chemical” which would require a “Workplace Chemical Protection Program” (WCPP) with exposure monitoring. However, this is not explicitly clear.

Comments should be submitted before June 2, 2023. Has DCHAS discussed submitting a response? Should we?

Chris

Christine Rogers, PhD, CIH

Director of Research Safety

Environmental Health & Safety

Cornell University

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