Methylene Chloride/Dichloromethane Under TSCA

The Environmental Protection Agency (EPA) published a final ruling for use of DCM effective July 8, 2024. Under the Toxic Substances Control Act (TSCA), the ruling addresses any unreasonable risk of injury to health and life presented by the use of methylene chloride to any potentially exposed persons including researchers, visitors, and any other person entering the space of use. The EPA ruling for DCM impacts The University of Alabama campus including, but not limited to, laboratories, research, and research-related spaces.

Any work conducted within a laboratory or research-related space is considered commercial use by the ruling and therefore subject to the inhalation exposure concentration limits and exposure monitoring outlined in the ruling.

DCM has been deemed to pose a cancer health risk. As part of the ruling, the EPA mandates certain requirements be established to mitigate unreasonable risk caused by uncontrolled exposure to DCM.

Prohibition of commercial use of DCM will occur on May 8, 2029 (at the latest). Anyone who anticipates continued use of the chemical until this deadline will need to adhere to strict requirements such as:

Establishment of a Workplace Chemical Protection Program (WCPP) which includes the establishment of regulated areas for use
Exposure monitoring
Use of air-supplied full face respirators
Skin (dermal) protection
Recordkeeping
Training
Development of an exposure control plan

Final Compliance Dates and Working Timeframes from Publication of Final Rule

WCPP Compliance Phase	General Industry	Federal Agencies and Federal Contractors
Initial Monitoring	May 5, 2025 / 12 months	November 9, 2026 / 30 months
ECEL/EPA STEL	August 1, 2025 / 15 months	February 8, 2027 / 33 months
PPE/Respirators	August 1, 2025 / 15 months	February 8, 2027 / 33 months
Establish Regulated Area	August 1, 2025 / 15 months	February 8, 2027 / 33 months
Exposure Control Plan	October 30, 2025 / 18 months	May 8, 2027 / 36.5 months

The ruling specifically outlines the following limits*:

De minumus thresholds of 0.1% for products containing DCM
Existing Chemical Exposure Limit (ECEL) of 2ppm as an 8-hr TWA
Action level of Existing Chemical Exposure Limit (ECEL) of 1ppm as an 8-hr TWA
Short Term Exposure Limit (STEL) of 16ppm as a 15-min TWA

*It should be noted that use of a fume hood does not automatically lead to exposure limits below the ECEL. Several studies conducted have indicated that occupational exposure to DCM can be elevated past the ECEL based on the scenario. Therefore, any continued use of DCM will require further review by EHS and supporting evidence by the PI to justify the continued use of DCM.

Source	Worker Activity	Methylene Chloride Concentration (PPM)
Mccammon (1990)	Sample concentrating	2.7
	Sample concentrating	3.9 – 4.5
	Washing separatory funnels in a sink near extraction	110
	Sample concentrating	4.2 – 30
	Transferring 100 mL methylene chloride into soil samples	9.8
	Collecting waste and dumping into chemical storage	1,000
Defense Occ. and Env. Health Readiness System	Miscellaneous Lab Operations	3.1
Industrial Hygiene (DOEHRS-IH) (2018)	Sample extraction and analysis	34.7
	Gas chromatography extraction	0.7
	Lab activities	3.3 – 16.6

Notification:

EHS encourages elimination or, where elimination is not possible, substitution, of all uses of DCM. All uses or need of DCM in processes or research should be evaluated, and a response submitted to EHS by November 1, 2024, as any continued use of DCM will require the establishment of a Workplace Chemical Protection Program (WCPP) and all related components. Lab Safety must receive a response with a course of action to discuss a path forward either with elimination, substitution, or continued use of DCM.

Requirements for Continued Use of DCM:

If continued use of DCM is deemed necessary, a timeline for initial monitoring must be outlined ASAP as this monitoring must be completed for existing facilities throughout campus prior to May 5, 2025. This initial monitoring is used to establish a baseline of exposure for potentially exposed individuals, with periodic monitoring to assure continued compliance and protection from methylene chloride over time.

Additionally, a WCPP must be established if any use of DCM is to continue for any duration of time. Any persons with the potential for exposure must be provided protection, including respiratory and dermal protection. Any spaces with DCM above the established exposure limits will become regulated areas. An exposure control plan must be developed and implemented. Monitoring records must be provided to any person monitored as part of the exposure control plan. The exposure control plan must be in place by October 30, 2025. Periodic monitoring will occur as outlined based upon initial monitoring results:

Periodic Monitoring Requirements Based on Initial Exposure Monitoring Results

Air concentration condition observed during initial exposure monitoring	Periodic monitoring requirement
If the initial exposure monitoring concentration is below the ECEL action level and at or below the EPA STEL.	ECEL and EPA STEL periodic monitoring at least once in every 5 years.
If the initial exposure monitoring concentration is below the ECEL action level and above the EPA STEL.	ECEL periodic required at least once every 5 years, EPA STEL periodic monitoring every 6 months.
If the initial exposure monitoring concentration is at or above the ECEL action level and at or below the ECEL and at or below the EPA STEL.	ECEL periodic monitoring every 6 months.
If the initial exposure monitoring concentration is at or above the ECEL action level and at or below the ECEL and above the EPA STEL.	ECEL periodic monitoring every 6 months and EPA STEL periodic monitoring every 3 months.
If the initial exposure monitoring concentration is at or above the ECEL action level and below, at, or above the EPA STEL.	ECEL periodic monitoring every 3 months and EPA STEL periodic monitoring every 3 months.
If 2 consecutive monitoring events have taken place at least 7 days apart that indicate that potential exposure has decreased from above the ECEL to at or below the ECEL, but at or above the ECEL action level.	Transition from ECEL periodic monitoring frequency from every 3 months to every 6 months.
If 2 consecutive monitoring events have taken place at least 7 days apart that indicate that potential exposure has decreased to below the ECEL action level and at or below the EPA STEL.	Transition from ECEL periodic monitoring frequency from every 6 months to once every 5 years. The second consecutive monitoring event will delineate the new date from which the next 5-year periodic exposure monitoring must occur.
If the owner or operator engages in any conditions of use described in paragraph (a) of this section and is required to monitor either the ECEL or EPA STEL in a 3-month interval, but does not engage in any of those uses for the entirety of the 3-month interval.	The owner or operator may forego the upcoming periodic monitoring event. However, documentation of cessation of use of methylene chloride must be maintained, and initial monitoring is required when the owner or operator resumes or starts any of the conditions of use described in paragraph (a) of this section.
Owner or operator engages in any conditions of use described in paragraph (a) of this section and is required to monitor the ECEL in a 6-month interval, but does not engage in any of those uses for the entirety of the 6-month interval.	The owner or operator may forego the upcoming periodic monitoring event. However, documentation of cessation of the condition(s) of use must be maintained until periodic monitoring resumes, and initial monitoring is required when the owner or operator resumes or starts any of the conditions of use described in paragraph (a) of this section.