OVERVIEW OF N-PROPYLBROMIDE (NPB)

UNITED STATES

Several solvents used in industrial parts cleaning operations, including cleaning processes before and after heat treatment, are regulated under the Toxic Substances Control Act (TSCA) and have undergone risk evaluation by the U.S. Environmental Protection Agency (EPA). These solvents include 1-bromopropane (1-BP or nPB), trichloroethylene (TCE), perchloroethylene (PCE), methylene chloride (DCM), and trans-dichloroethylene (t-DCE). 

While other federal and state regulations may also affect industrial cleaning applications, such as the Clean Air Act, NESHAP, the Resource Conservation and Recovery Act (RCRA), and the Clean Water Act, this overview focuses on the TSCA regulatory framework. Companies should additionally consider state-specific requirements, particularly in states such as California, where restrictions may exceed federal requirements.

Under TSCA, EPA first evaluates whether a chemical presents an unreasonable risk to human health or the environment and subsequently develops risk management measures to address those risks. In December 2022, EPA issued a revised final risk determination for 1-BP and concluded that the chemical presents an unreasonable risk to human health as a whole chemical substance, including risks to workers, occupational non-users, consumers, and bystanders. EPA identified concerns including neurotoxicity, developmental toxicity, reproductive effects, and cancer resulting from inhalation and dermal exposure. 

EPA Proposed Risk Management Rule

On August 8, 2024, EPA published a proposed risk management rule for 1-BP under TSCA. The proposal is intended to address the unreasonable risks identified during the risk evaluation process while maintaining certain industrial uses that can be managed through strict workplace controls. 

According to EPA, if finalized largely as proposed:

• Most consumer uses of 1-BP would be prohibited.
• Certain industrial and commercial uses would also be prohibited where technically and economically feasible alternatives are available.
• Selected industrial and commercial uses, including vapor degreasing and other critical applications, could continue under a Workplace Chemical Protection Program (WCPP).
• Employers using 1-BP in permitted applications would be required to implement exposure monitoring, worker protection measures, training programs, and recordkeeping requirements. 

Workplace Chemical Protection Program (WCPP)

A key element of the proposed regulation is the establishment of a Workplace Chemical Protection Program (WCPP) for uses that would remain permitted.

Under the proposed rule, EPA introduced an Existing Chemical Exposure Limit (ECEL) of 0.05 ppm as an 8-hour time-weighted average exposure limit. Facilities wishing to continue using 1-BP in allowed applications would be required to demonstrate compliance with this exposure limit through engineering controls, exposure monitoring, workplace practices, and other protective measures. 

For industrial cleaning applications, particularly vapor degreasing, the proposed ECEL is widely recognized as one of the most stringent workplace exposure limits proposed under EPA's recent TSCA risk management actions.

Current Regulatory Status

As of October 2026, EPA has not yet finalized the 1-BP risk management rule. The August 2024 proposal remains under review while EPA evaluates stakeholder comments and prepares a final rule. 

According to the Office of Information and Regulatory Affairs (OIRA) regulatory agenda, EPA is currently developing a final TSCA risk management rule for 1-BP based on the August 2024 proposal. The agency's stated objective remains to:

• Prevent consumer access to 1-BP.
• Restrict industrial and commercial uses presenting unreasonable risk.
• Provide transition periods where uses will be prohibited.
• Establish worker protection measures for uses that remain permitted. 

Implications for Vapor Degreasing Users

For companies currently using 1-BP in vapor degreasing applications, the most important takeaway is that EPA's proposed approach differs from the complete phase-out adopted for methylene chloride and largely adopted for trichloroethylene. Under the current proposal, vapor degreasing could remain permissible provided facilities can comply with the WCPP requirements and achieve the proposed exposure limit of 0.05 ppm. However, this approach will only become legally binding once EPA issues its final rule. 

Regulatory Outlook

EPA continues to view 1-BP as a chemical presenting significant health risks, and some form of federal risk management requirements are expected. While the final rule has not yet been published, companies using 1-BP should closely monitor EPA developments and begin evaluating whether workplace exposures can be reduced sufficiently to meet the proposed ECEL of 0.05 ppm. Users of 1-BP in vapor degreasing and other industrial cleaning applications should also assess potential alternative solvents and technologies as part of their long-term compliance planning. 

Further Information

• Final Risk Evaluation for 1-Bromopropane (1-BP) epa.gov
• Risk Management for 1-Bromopropane (1-BP) epa.gov
• 1-Bromopropane (1-BP); Regulation Under the Toxic Substances Control Act (TSCA) - Proposed Rule federalregister.gov, govinfo.gov