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How to Prepare Your Lab for the EPA Methylene Chloride Ban

Learn why the EPA banned methylene chloride, its risks, and new lab compliance steps

Kimi Brown, NRCC-CHO, CSP, ARM

Kimi Brown, NRCC-CHO, CSP, ARM is the product engineer at SciShield, a global leader in EHS and lab ops software, where she lends her subject matter expertise as a former...

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In April of 2024 the Environmental Protection Agency (EPA) finalized a rule banning most uses of methylene chloride (CAS RN: 75-09-2).

Read on to learn: Why they are banning this chemical? Why now? And how this will this impact laboratories, where methylene chloride is still critical to chemical research.

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What are the risks of methylene chloride?

If you have worked with methylene chloride (common synonyms: dichloromethane, DCM, MC), you likely know that it is nasty stuff. Short-term exposures can affect the central nervous system, and chronic exposures can lead to liver toxicity, liver cancer, and lung cancer. It is highly volatile and quickly penetrates standard thickness disposable gloves, which makes it challenging to protect against both inhalation and skin absorption exposures. Like many highly potent chemicals, the properties that make it so hazardous are also what make it useful for commercial, industrial, and research purposes. It has a low boiling point and is a polar aprotic solvent, making it ideal for degreasing, paint stripping, aerosols, and a variety of laboratory applications including synthesis, extraction, and purification.

The Occupational Safety and Health Administration (OSHA) has regulated methylene chloride to protect workers in general industry since 1997 (29 CFR 1910.1052). This new regulation from the EPA, however, covers a broader range of potentially exposed persons and imposes even stricter limits on the acceptable levels of exposure.

Why is the EPA banning methylene chloride now?

If this infamously hazardous material has already been regulated for decades, why is the EPA only now imposing this ban? The answer is, in short, because now they can.

In 2016, congress passed legislation to revise the EPA’s Toxic Substances Control Act (TSCA). This law gives the agency new powers and responsibilities for ensuring that “no chemical in U.S. commerce poses an unreasonable risk to human health or the environment.” Methylene chloride is among the first 10 chemicals in a list of 90 high-risk substances for which the EPA will now be conducting mandatory risk reviews to determine whether chemical bans and regulations are warranted.

The EPA’s evaluation of methylene chloride in November of 2022 determined that it does present “an unreasonable risk of injury to health.” As a result, in May of 2023, the EPA proposed the methylene chloride ban, and after a period of public comment, they finalized the rule in April of 2024. 

Does this ban apply to laboratory use?

Although the rule does not impose a complete ban on the use of methylene chloride, it does prohibit it in most industrial, commercial, and consumer uses. The EPA, however, is allowing for “limited and controlled continued use in tandem with additional work protections for several purposes [. . .].” Among the list of 13 permitted uses is “industrial and commercial use as a laboratory chemical.”

The EPA explains that “laboratory settings are expected to be more conducive to the implementation of engineering controls such as fume hoods to ventilate vapors and adequately reduce overall exposure to methylene chloride consistent with the hierarchy of controls.” Of course, the use of methylene chloride in a laboratory setting will also be necessary for the analysis of the air samples that this rule requires.

What will the requirements be for laboratories that continue to use methylene chloride?

While laboratories may continue to use methylene chloride, they will be required to have a Workplace Chemical Protection Program (WCPP) in place. The WCPP details requirements for air monitoring to make sure that the amount of methylene chloride vapor is below the allowable concentration. It also specifies record keeping requirements, and other measures such as dermal protection.

Because of the new, lower exposure thresholds set by the EPA, even organizations that are currently in compliance with the OSHA methylene chloride standard will need to perform these baseline monitoring activities. These measurements and analyses will be done either by qualified industrial hygienists from the organization’s health and safety department or, if the necessary equipment or expertise is not available in-house, by contracted safety professionals.

If any of the results from the air monitoring exceed the allowable amounts, additional periodic monitoring will be required, and each potentially exposed person must be notified of the results. The facility will also need to create an exposure control plan (ECP) to document what was done to reduce both inhalation and dermal exposures to an acceptable level.

Timeline for compliance for (non-governoment) laboratories
Required actionAmount of time after publication date of the final rule in the Federal Register
Establish initial exposure monitoring
360 days (and every 5 years thereafter)
Ensure exposure thresholds are not exceeded 450 days
If needed, sufficient respiratory protection provided to reduce exposures below thresholds9 months (or 3 months after receipt of monitoring results)
Implement and document exposure control plan540 days

What can laboratories do to prepare for the new requirements?

Do we have any methylene chloride?

You can start checking now to see if you are storing and/or using methylene chloride. If you have a trusted chemical inventory system, that could be as easy as searching the records for methylene chloride by name, CAS RN (75-09-2), and by any of the common synonyms (dichloromethane, DCM, MC).

This chemical is not flammable, so it is not always stored in the flammable liquids storage cabinet; however, it can sometimes be found in locations where other solvents are stored.

Can we just stop using methylene chloride?

There are some suggested substitutions for some use cases, but there might still be lab operations where methylene chloride will be required. In a 2008 article in Green Chemistry, the Environmental, Health and Safety (EHS) group at Pfizer Global Research and Development recommended replacing methylene chloride with Ethyl Acetate/Hexane for chromatography and with Ethyl Acetate, MTBE, Toluene, or 2-MeTHF for extractions.

Teledyne ISCO suggests a 3:1 ratio of ethyl acetate to ethanol as a starting point for creating new methods without DCM for chromatography purification.

Chromatography and extraction are good targets for substitution because they are two of the most common and high-volume laboratory tasks where methylene chloride is used.

Even if you can’t eliminate it entirely, reducing the quantity and frequency of use increase the safety of your lab and will make compliance with the regulation much easier.

How can we convince lab personnel to make these changes?

It is important that your laboratory personnel are made aware of the hazards and the new requirements as soon as possible to get their buy-in and to enable a smooth transition.

One strategy for encouraging the use of alternative solvents is to enforce limits on the total permitted amount and/or the largest permitted container size of methylene chloride. By not instituting a complete ban, you enable critical processes to continue while still promoting the use of substitutions by making it less convenient to use the more hazardous chemical.

What’s next?

The reality is, for many laboratory facilities, the use of methylene chloride cannot be fully eliminated. However, if leadership keeps a collaborative mindset and focuses on risk assessment and mitigation, they will benefit from the creativity and problem-solving skills that laboratory workers bring to the conversation.

After all, this will lay the groundwork for compliance with many similar regulations in the coming years. At the time of writing this article, the EPA is currently evaluating 33 existing chemicals under the revised Toxic Substances Control Act to determine which others present unreasonable risk of injury to health or the environment; methylene chloride is simply the first to have a final published rule. The strategies and relationships developed now will set the precedent for successful responses to these future EPA chemical bans and restrictions.

Checklist to Prepare Your Lab for the EPA Methylene Chloride Regulation

Communicate and Plan Ahead

  • Share this article with your lab members, and let them know what to expect
  • Identify where methylene chloride is stored or used in the lab
  • Contact your organization’s safety leadership to see how you can help prepare for a smooth transition

Check Equipment 

  • Confirm that local exhaust ventilation controls such as fume hoods and extractors are in service, inspected, and certified

Eliminate and Substitute Where Possible

  • Consider applications where you can eliminate or substitute methylene chloride with a safer alternative
    • Consider instituting limits on total volumes or largest-container size to encourage the use of alternatives
  • Identify where and how methylene chloride must still be permitted
    • Consider requiring a written approval (e.g., a permit) for any project or team where methylene chloride use will be allowed

Plan for Initial and Ongoing Compliance

  • Make sure you have a way to identify is methylene chloride is ordered or needed for future projects
  • Update initial and refresher training for chemical handling to highlight the health hazards of methylene chloride and any new approvals or other requirements that will be put in place