Methylene Chloride (Dichloromethane)

The Environmental Protection Agency (EPA) recently published a rule to address the unreasonable risk of injury to health presented by methylene chloride (AKA dichloromethane or DCM). The EPA's final rule, among other things, serves to prevent serious illness and death associated with uncontrolled exposures to the chemical by preventing consumer access to the chemical, restricting the industrial and commercial use of the chemical, and protect workers from the unreasonable risk of methylene chloride while on the job.

The EPA rule allows for limited and controlled use for research purposes with additional prescribed workplace protections. Non-research use of DCM is prohibited by this ruling. Environmental Health & Safety will help TTU personnel adapt to this new regulation in the following ways:

• Identifying users of DCM
• Performing initial exposure monitoring to determine exposure levels and notification of additional required work protections
• Assist in removing DCM and DCM-containing products from spaces through hazardous waste pickup requests
• Assist in identifying solvent alternatives (see Resources section below)
• Provide training on safe and legal use of DCM
• Establish a DCM Exposure Control Plan
• Subsequent periodic monitoring to ensure levels remain below reported thresholds

How does this apply to me?

For the purposes of the DCM rule, the EPA emphasizes that use of DCM as a laboratory chemical applies to research, government, and academic institutions, as well as to industrial and commercial laboratories. This includes the use of DCM in a laboratory process or in specialized laboratory equipment for instrument calibration and maintenance, chemical analysis, chemical synthesis, extracting and purifying other chemicals, dissolving other substances, executing research, development, test and evaluation methods, and similar activities, such as use as a solvent, reagent, analytical standard, or other experimental use.

This rule applies to DCM or products containing DCM at >0.1%. Therefore, while certain commercial applications with this chemical are restricted or strictly prohibited, use as a laboratory chemical is approved so long as there is compliance with the EPA workplace chemical protection program (WCPP). For a detailed list of the reported conditions of use and potential DCM-containing products please see the Resources section below. 

Requested Actions

1. All TTU work areas that currently have any amount of DCM or DCM-containing products, have had DCM within approximiately the past 2 years, or who plan to obtain DCM must complete the Methylene Chloride Survey. Please be sure to check all chemical solutions, biological kits, instrument standards, etc. for DCM as some of these may contain DCM. This 5-minute survey will help EHS identify active users and can be done by the PI, lab or area manager, or lab safety captain. Only one survey per PI research group or supervisor area is required.
2. If your area(s) have DCM or DCM-containing products that are used for non-research purposes (paint stripper, paint, etc.), you will need to submit a waste collection request as soon as possible to have this removed. DCM is not permitted under this new ruling for non-research use.
3. If you have DCM but are not actively using the chemical, this ruling will still apply since storage of the chemical is also entailed. We highly recommend removal of any DCM bottles or containers that will not be used for current or future work. A waste collection request can be submitted at any time regardless of quantity of waste.
4. If there is active research in your area(s) which involves DCM and cannot be switched to a safer alternative, a detailed SOP must be written and distributed to your personnel. The SOP must cover all of the procedures specific to your research involving DCM, all important safety policies and information, and include all rooms where DCM is stored and used. 

What are the health risks of DCM?

The EPA performed a risk evaluation on DCM use and exposure in 2020. This report identified non-cancerous adverse effects from acute and chronic inhalation and dermal exposures to methylene chloride, and cancer from chronic inhalation and dermal exposures to methylene chloride. Specifically, the EPA reports that the primary health risks are neurotoxicity from short-term exposure to the chemical, and liver effects and cancer effects from long-term exposure.

From this data, the EPA determined that risk to workers, occupational non-users (workers nearby but not in direct contact with this chemical), consumers, and bystanders was “unreasonable” thus initiating the need for prohibitions and restrictions for use. The SDS for DCM can be found in the Resources section below.

What is the EPA WCPP?

The workplace chemical protection program (WCPP) is intended to protect potentially exposed persons in the workplace and who are engaged in conditions of use that are not prohibited by the 2024 EPA ruling. The WCPP includes definition of inhalation exposure limits, called existing chemical exposure limit (ECEL) and short-term exposure limit (STEL) to protect potentially exposed persons. Owners and operators have flexibility in selecting what controls are best for their facility when determining how to comply with the WCPP. Use of DCM that meets the criteria mentioned above, regardless of scale or volume, is regulated by the WCPP.

Other WCPP Required Provisions:

• Initial and periodic monitoring of DCM exposure levels
• Establishment of a designated area for use
• Development and communication of an exposure control plan
• Respirator selection criteria
• Recordkeeping
• Downstream notification

EPA Timeline

May 5th, 2025 – Completion of initial monitoring

August 1st, 2025 – Ensure DCM exposure is below reported limits (2ppm as an 8-hr Time Weighted Average (TWA) and 16 ppm as a 15-min TWA) and provide protections if applicable

October 30th, 2025 – Development and implementation of an Exposure Control Plan

How will EHS conduct exposure monitoring and create an exposure control plan?

Our chemical safety division will conduct exposure tests throughout this semester for areas that store and use DCM. Sampling will be done as needed using passive absorption badges and our EHS GasMet FTIR analyzer. For active sampling, EHS personnel will conduct these measurements in real time with minimal disruption to work. Advice for how to minimize exposure during tasks may be given by EHS.

Afterwards, your group will receive a report detailing the results of these measurements. After compiling data for all DCM areas, we will establish a TTU Exposure Control Plan according to the WCPP that contains detailed instructions for proper handling and storage of DCM, protocols for managing exposure to personnel, and requirements for recordkeeping and downstream notification. This plan will be incorporated into the Lab Safety Manual.

How can we protect ourselves?

When working with hazards, you should conduct a risk assessment and refer to the hierarchy of controls to rank and identify safeguards to protect personnel. The most effective way to control the hazards presented by DCM is to eliminate the chemical from the workplace or substitute it with a safer alternative.

When DCM must be used to properly conduct research experiments, then engineering controls should be used to isolate workers from the hazard. It is critical that DCM only be handled and manipulated in a fully certified fume hood or at least under direct ventilation (i.e., snorkel). If you suspect that your hood is not meeting minimum flow rates or was last inspected over a year ago, please submit a request for equipment testing by EHS.

The next line of defense is to implement administrative controls to dictate how the work is done and how the hazard is to be used, stored, and disposed. This includes, but is not limited to, training personnel on proper technique, posting signage to communicate DCM hazards, designating dedicated work areas or zones for DCM use, maintaining lab and lab equipment hygiene, and supervising workers to ensure competency in assigned tasks.

The last defense workers have against hazards is personal protective equipment (PPE). Standard wet lab PPE includes a lab coat, gloves, and safety goggles. Always verify compatibility of disposable gloves with the chemical(s) being used by referring to manufacturer recommendations and SDSs. Be sure to remove contaminated gloves immediately and wash hands and arms with soap and water. Refer to the Chemical Hygiene Plan or contact EHS at ehs.lab.safety@ttu.edu for additional guidance.

Resources

DCM SDS

EPA Fact Sheet

EPA Compliance Guide

EPA Compliance Guide – Conditions of Use

OSHA 1910.1052 – Methylene Chloride

EPA List of DCM-containing products

Alternative solvent recommendations and references

Green Chemistry Teaching and Learning Community – Methylene Chloride (DCM) Replacements

Sigma Aldrich – Greener Solvent Alternatives

Peptide Synthesis: 2-methyl tetrahydrofuran (2-MeTHF) or ethyl acetate

Solvent for Extractions/Chromatography or Purifications: Ethyl acetate, heptane, toluene, 2-MeTHF, methyl tert-butyl ether (MTBE)

Chromatographic Purification/Separation: Cyclopentyl methyl ether, or mixtures like dimethyl carbonate and methanol or ethyl acetate and isopropanol; can use reverse phase chromatography instead

Green Chromatography Solvent Mixtures: eluents and mixtures with heptanes, MTBE, methanol, ethanol, ethyl acetate, and isopropanol for separations involving neutral, acidic, and basic compounds

Replacements in Reactions: benzotrifluoride for Dess-Martin/Swern, Sakurai, Friedel-Crafts, and Diels-Alder reactions; 2-MeTHF for biphasic reactions such as  alkylation, nucleophilic substitution, or amidation; dimethyl carbonate for methylation and carbonylation reactions

Interactive Tool: Green Solvent Selection Tool

Video: LSI Use This Not That: Safer Substitutions for Methylene Chloride