EPA Bans Most Uses of Methylene Chloride

The U.S. Environmental Protection Agency (EPA) issued on May 8, 2024, a final rule under the Toxic Substances Control Act (TSCA) to address the unreasonable risk of injury to health presented by methylene chloride under its conditions of use (COU). To no one’s surprise, the EPA banned most uses of the chemical. However, surprisingly, the EPA also adopted a de minimis threshold to account for impurities and the unintended presence of methylene chloride. The final rule goes into effect July 8, 2024. Here is a summary.

Applicability

The final rule sets restrictions on the manufacture, including import, processing, distribution in commerce, commercial use and disposal of methylene chloride to prevent unreasonable risk of injury to health. Because the EPA determined the chemical presents an unreasonable health risk within the United States, the rule applies even if methylene chloride is manufactured, processed or distributed solely for export.

As noted, the EPA adopted a de minimis threshold of 0.1% to account for impurities and the unintended presence of methylene chloride; thus, the final rule applies only when methylene chloride is present in a formulation at 0.1% or greater. The final rule also applies only to chemical substances as defined under TSCA Section 3 and excludes from the definition chemical substance uses subject to the Federal Food, Drug and Cosmetic Act and the Federal Insecticide, Fungicide and Rodenticide Act.

Workplace Chemical Protection Program

The EPA is implementing the Workplace Chemical Protection Program (WCPP) for certain COUs, including among others, domestic manufacturing; import; processing as a reactant; processing for incorporation into a formulation, mixture or reaction product; processing in repackaging; processing in recycling; and industrial and commercial use as a laboratory chemical. 

WCPP requirements take effect on May 5, 2025, for the private sector and on Nov. 9, 2026, for federal agencies and federal contractors acting for or on behalf of the federal government, at which point entities would be required to conduct initial monitoring. 

Chemical Exposure Limits

The EPA requires each owner or operator ensure the airborne concentration of methylene chloride does not exceed the existing chemical exposure limit (ECEL) or EPA short-term exposure limit (STEL) for all potentially exposed persons no later than Aug. 1, 2025, for the private sector, or no later than Feb. 8, 2027, for federal agencies and federal contractors.

The EPA is codifying that owners or operators must ensure the airborne concentration of methylene chloride within the personal breathing zone of potentially exposed persons remains at or below 2 parts per million (ppm) as an eight-hour time-weighted average (TWA) ECEL, with an action level of 1 ppm as an eight-hour TWA. 

The EPA is promulgating as proposed that owners or operators must also ensure the airborne concentration of methylene chloride within the personal breathing zone of potentially exposed persons remains at or below a 15-minute TWA, or EPA STEL, of 16 ppm. The EPA is adopting the ECEL and EPA STEL for certain occupational COUs to ensure no person is exposed to inhalation of methylene chloride in excess of these concentrations.

The final rule requires owners or operators determine each potentially exposed person’s exposure by taking a personal breathing zone air sample or by taking personal breathing zone air samples representative of each potentially exposed person’s exposure. The latter involves taking one or more samples for at least one potentially exposed person in each job classification in a work area during every work shift, and the person sampled is expected to have the highest methylene chloride exposure; or when one or more samples are taken that indicate the highest likely 15-minute exposures during such operations for at least one potentially exposed person in each job classification in the work area during every work shift, and the person sampled is expected to have the highest methylene chloride exposure. 

Air sampling is required to measure ambient concentrations for methylene chloride without taking respiratory protections into account as sampling is being performed. The final rule also requires the owner or operator ensure, for initial and periodic monitoring, that their exposure monitoring methods are accurate to a confidence level of 95% and are within ±25% of airborne concentrations of methylene chloride above the eight-hour TWA ECEL or the 15-minute TWA EPA STEL, or within (plus or minus) 35% for airborne concentrations of methylene chloride at or above the ECEL action level but at or below the eight-hour TWA ECEL. To ensure compliance for monitoring activities, the EPA is adopting recordkeeping requirements and will require owners or operators document their choice of monitoring method.

Exposure Control Plan

The final rule requires entities implementing the WCPP use elimination and substitution, followed implementation of engineering controls, administrative controls and work practices prior to requiring the use of personal protective equipment (PPE) as a means of controlling inhalation exposures below the EPA’s ECEL or STEL. The EPA expects that, for COUs for which the EPA is requiring a WCPP, “compliance at most workplaces would be part of an established industrial hygiene program that aligns with the hierarchy of controls.”

Under the final rule, the owner or operator must demarcate any area where airborne concentrations of methylene chloride are reasonably expected to exceed the ECEL or the EPA STEL. The demarcation may be done “in any manner that adequately establishes and alerts potentially exposed persons to the boundaries of the area and minimizes the number of authorized persons exposed to methylene chloride within the regulated area.”