What Is the Truth About the Toxicity of nPB?

The brominated molecule known as nPB (also called n-Propyl Bromide, 1-Bromopropane or CAS # 106-94-6) is a nonflammable fluid. It is a powerful cleaner with a low global warming potential. It is used as an alternative to CFC-113, methyl chloroform, hydrochlorofluorocarbons (HCFCs) and perfluorocarbons (PFCs) in many critical cleaning, drying, carrier fluid and other high-value specialty uses where reliability is paramount.

Based upon toxicological research, the ACGIH set the Acceptable Exposure Limit (AEL) is 0.1 parts per million (ppm), using the 8-hour time weighted average (TWA) methodology. This means ANY nPB product cannot be safely used in an uncontrolled environment, such as an aerosol dispenser. nPB used in vapor degreasing is also under scrutiny by many governmental agencies. 

The Hazards Associated with nPB

In simple terms, the hazards associated with n-propyl bromide can be viewed with regards to short and long term exposure. Early on, the U.S. National Toxicology Program recommended a No Observable Adverse Effect Level (NOAEL) for nPB of 100 ppm, which, with a sensible ten-fold safety factor, led to a  10 ppm (parts per million) exposure limit recommendation.

But more recent research suggests there are significant toxicity worries. From a long-term viewpoint, tests in animals have shown long-term overexposure to nPB may lead to multiple adverse affects in the body likely including fertility problems for both males and females. Recent health studies have found nPB damages the nervous system, alters human DNA, impairs fertility and there is a risk of cancer.

Based on these reports, the European Chemicals Agency (ECHA) listed nPB as a ‘Substance of Very High Concern’ in December 2012 and nPB was bannedas an industrial cleaner in Europe in 2020.

The government of Ontario, Canada also has become concerned about the long-term toxicity of nPB.  In July 2017 the Ministry of Labour enacted new worker-safety rules which restrict the deployment of this widely-used chemical. Today the aceptbale exposure limit is 0.1 ppm. 

In the US, several government agencies originally recommended 10 ppm as the proper exposure limit. Separately, California adopted a 5 ppm limit and an independent safety agency, the American Conference of Governmental Industrial Hygienists (ACGIH), lowered their recommended exposure rating to just 0.1 ppm in 2014.

A Ban on nPB is Certain

Today, nPB is under scrutiny by the U.S. EPA (Environmental Protection Agency), OSHA (Occupational Health and Safety Administration). In 2018, the EPA added nPB to its TOSCA (Toxic Substance Control Act) list. In August, 2020 the EPA reported that nPB presents unreasonable risk to human health and should be restricted as a cleaner or degreaser.

This report is just a preliminary step for the EPA. It will likely lead to a complete EPA ban on nPB by 2023. nPB is already sunset or banned in Europe as of July 2020. And many other countries are likely to follow and ban the use of nPB in the near future.

MicroCare offers a variety of good substitutes for n-Propyl Bromide. These high-purity, non-flammable, sustainable vapor degreaser fluids provide superb cleaning on both polar and non-polar soils.

These fluids have low viscosity and surface tension. This allows the fluids to permeate tight crevices and wet all the surfaces of the parts. They are also are high solvency (with high Kb Values) which allows them to rigorously clean surfaces and displace tough soils, yet not damage delicate materials.

  • Tergo™ Metal Cleaning Fluid An environmentally sustainable azeotropic cleaner engineered for fast, consistent and economical cleaning in vapor degreasers
  • Opteon™ SF80 Cleaning Fluid Opteon™ SF80 combines the high solvency needs for industrial cleaning with and environmentally-friendly low GWP (Global Warming Potential)
  • Other custom formulations and pending prototype currently in development may also be available.