Friday, May 3, 2024

The impacts of the new EPA rule on methylene chloride to laboratories in the United States

I have been making nervous noises about the EPA ban on methylene chloride, and I believe that my thoughts are confirmed (unbeknownst to me) by the American Chemical Society's comment on the (then proposed) rule (opens PDF, via ACS' Will Hartwig):

ACS appreciates the current proposed rule’s goal of protecting public health. However, ACS is concerned that the current proposal to regulate methylene chloride, also known as dichloromethane (DCM), fails to account for its use in small scale and particularly academic teaching and research laboratories.

Both the EPA (with 40 CFR 262 Subpart K) and OSHA (with 29 CFR 1910.1450) have recognized that regulations aimed at protecting workers in industry do not translate to academic laboratories. As currently structured, the rule would be extremely challenging for academic institutions to implement and would negatively impact research and teaching. The proposed rule is not appropriate for academic laboratories because exposures are low, infrequent, and well managed using existing regulations and engineering controls (e.g. chemical fume hoods)

From my analysis of the new rule, any workplace that uses methylene chloride must:

  1. determine and document who uses DCM
  2. document and monitor the exposure during usage, which
  3. means getting a monitoring device (likely a PID, is my guess, which is a $4000 instrument)*
  4. determining and documenting TWAs for each usage and user

(I've read enough comments from industry to understand that the PIDs that are available aren't particularly well suited for this usage, so that's another problem. (page 6, PDF)

I'm not a chemical safety professional, so I could be wrong. But that's my basic read of the new rule, and I think it is matched by the ACS. No professor is going to this - instead, they're going to either 1) ignore the new rule or 2) ban the use of DCM in their labs. Hard to know which one they will choose.

I'd love people's opinions.


  1. What's the replacement for DCM? Chloroform is worse in every way. Trifluorotoluene is higher boiling (both good and bad) and is likely not available on large scale (or cheap); it may also be a problem if the PFAS regs from the EU are enacted. I don't know what other alternatives are (and I have to imagine that if there was a really good alternative, paint strippers wouldn't have been using it).
    It seems like we're at the point where substances without good replacements have enough hazard to no longer be usable - what do we do? People seem to disagree about what are "necessary" applications (the people that sell products using them and people who want to get rid of them have diverging opinions of their necessity) and what we do for "unnecessary" applications. - Hap

  2. While I strive to use ethyl acetate in its place where I can as a solvent in purification, there are plainly some cases where DCM is better. Then you have all the existing literature and reactions on top of it. I see sense in regulating unventilated and larger scale environments. But for smaller scale research and academic labs with ventilated systems, I don't see a need for regulating access. It's an extremely volatile solvent that doesn't stick around long. The biggest concern I ever see with it is poor glove hygiene.

  3. Small academic laboratories are the most concerning in my opinion. The most egregious lab safety offences I have observed occured in small academic laboratories at the large university where I was a grad student. All of my subsequent industry experience has been far safer with many more safeguards in place.

  4. I complained to OSHA about them forcing us to pour the hazardous waste generated in the hood into a can OUTSIDE of the hood. The complaint was anonymous but I came forward about it. All they did was harass me over it, no class. How hypocritical, aren't they supposedly working on cures for cancer? BTW, after I quit over the harassment they made changes. PS I first made this LBQ657 nonsense when I was there, they make billions with it, only problem is there is no evidence it does anything, many doctors crying foul over it. Billions in lost Healthcare dollars and a harvard professor is behind it


looks like Blogger doesn't work with anonymous comments from Chrome browsers at the moment - works in Microsoft Edge, or from Chrome with a Blogger account - sorry! CJ 3/21/20