Dichloromethane (DCM) Safety and Regulatory Compliance
Background
In May of 2024, the Environmental Protection Agency (EPS) issued a final rule under the Toxic Substances Control Act (TSCA) for Methylene Chloride, also known as Dichloromethane (DCM), and the resulting regulation went into effect in July 2024. This regulation stems from the EPA’s evaluation that the use of DCM presents an unreasonable risk of injury to health due to acute human lethality. The evaluation is based on the assessment for methylene chloride issued by the EPA in 2020 pursuant to TSCA section 6(b). The details of the EPA’ unreasonable risk determination were finalized in November 2022.
The regulation places DCM on the EPA’s regulatory list and restricts its use for many industries and applications. This rule does not ban the use and handling of DCM in research laboratories. However, laboratory use is permitted only when covered by a compliant Workplace Chemical Protection Program (WCPP). The regulation also sets a requirement for monitoring of activities in the laboratory to determine if workers are exposed to unsafe levels of DCM. Newly established levels for DCM exposure (8-hr TWA* = 2ppm, 15-minute STEL* = 16ppm, Action Level = 1ppm) are considerably lower than those previously used by OSHA and NIOSH.
*TWA = Time Weighted Average, STEL = Short Term Exposure Limit
How can your lab minimize DCM exposure?
The best ways to minimize DCM exposure and provide a safe environment for researchers are to replace it where possible, reduce quantities where possible, and to utilize appropriate engineering controls when its use is necessary.
- Replacement: Below are some possible alternatives to DCM and selected references for various applications.
| Application | DCM Alternatives | Selected References |
| Extraction and chromatography | Ethyl Acetate, Heptane, Toluene, 2-MeTHF, Methyl tert-butyl ether | Green Chemistry Tools Replacement Solvent for DCM in Chromatography Alternatives: Extraction and Purification UPenn Fact Sheet: Solvent Alternatives |
| Peptide synthesis | 2-MeTHF, Ethyl Acetate | Green Solid-Phase Peptide Synthesis |
| Various organic synthesis reactions | Reaction dependent | Alternatives in Organic and Medicinal Chemistry Greener Solvent Alternatives, Sigma-Aldrich |
- Reduction
- Reduce quantities of DCM used in applications where it is utilized when possible.
- Only purchase quantities of DCM that will be used in a reasonable amount of time (a few months as opposed to an entire year or more).
- If your lab has DCM that is no longer in use and will not be used, submit a hazardous waste pickup request through Lumen.
- Engineering Controls
- Lab use of DCM in chemical fume hoods and any other “closed” systems (where DCM cannot evaporate to the lab atmosphere) will protect the health and safety of our researchers and mitigate many of regulatory requirements from the EPA regulation. Move all activities using DCM to a chemical fume hood where possible.
- If instrumentation and equipment (using DCM) is not a closed system, and/or is too large to fit inside a chemical fume hood, other forms of engineering controls should be pursued (e.g., sealed tops of waste vessels, sealing leak points, snorkel hoods placed over “open to atmosphere” points, etc.) where possible.
- Store DCM in appropriate chemical storage cabinets, and collect DCM-containing waste in chemical fume hoods.
What do you need to do to ensure compliance with EPA and OSHA?
To determine if researchers are exposed to unsafe levels and to determine what actions need to be taken to mitigate these exposures, the university must conduct some initial monitoring (i.e., personal breathing zone air sampling) for those working with dichloromethane. Research Safety needs your assistance to better understand dichloromethane use at NU and in determining where we need to conduct initial monitoring.
- Please fill out the DCM use survey regarding the use of DCM in your lab by December 6, 2024. Fill out the survey even if dichloromethane is not used in your lab or if it is used minimally.
- If it is determined that monitoring needs to occur for your lab, research safety will contact you to arrange and schedule this. Initial monitoring is proposed to take place January through March 2025.
- The Office of Research Safety will work with labs and/or facilities where DCM exposure is above action levels to develop an exposure control plan to reduce researcher exposure and perform follow-up and periodic monitoring to verify the exposure control plan is effective in compliance with the new EPA regulations.