New National Emphasis Program focuses on reducing isocyanate exposure

The Occupational Safety and Health Administration (OSHA) recently developed a National Emphasis Program (NEP) to focus on workplace health issues derived from occupational exposure to isocyanate.

Isocyanates are compounds containing the isocyanate group (-NCO); a highly reactive, low molecular weight family of chemicals. They react with compounds containing alcohol (hydroxyl) groups to produce polyurethane polymers. Isocyanates are the raw materials that make up all polyurethane products. [1]

The goal of the NEP is to reduce employee exposure to isocyanates shown to potentially cause work-related asthma, sensitization and other occupational health effects.

This goal will be accomplished by a combined effort of inspection targeting, outreach to employers, and compliance assistance. OSHA aims to raise awareness of the occurrence and severity of occupational health hazards related to or associated with isocyanates in all industry sectors. [2]

Unsure if you work with isocyanates? — Chances are you do

Since isocyanates are the base of virtually all polyurethane products, they are found in a vast majority of industries and products. A general listing of applications includes [5]:

  • Automotive – paints, glues, insulation, sealants and fiber bonding, truck bed lining
  • Casting – foundry cores
  • Building and construction – sealants, glues, insulation material, fillers
  • Electricity and electronics – cable insulation, PUR coated circuit boards
  • Mechanical engineering – insulation material
  • Paints – lacquers
  • Plastics – soft and hard plastics, plastic foam and cellular plastic
  • Printing – inks and lacquers
  • Timber and furniture – adhesives, lacquers, upholstery stuffing and fabric
  • Textile – synthetic textile fibers
  • Medical care – PUR casts
  • Mining – sealants and insulating materials
  • Food industry – packaging materials and lacquers

Reducing hazardous exposure to isocyanates is incredibly important to the health and safety of workers in these industries.

Workplace exposure limits

The most commonly used isocyanates are toluene diisocyanate (TDI) and methylene bisphenyl isocyanate (MDI). TDI is used in the production of soft synthetic rubbers. MDI is used in producing foams, hard synthetic rubbers (elastomers), and coatings. Other isocyanates include: [7]

NDI is used to produce elastomers. HDI and IPDI are both used in paints, coatings, leather finishings, and foams.

Each species of isocyanates has their own occupational exposure limits. Multiple regulating agencies have outlined these limits in the below chart.










Multiple exposure routes mean a multitude of side effects

Side effects of isocyanate exposure include irritation of skin and mucous membranes, chest tightness, and difficulty breathing.

Isocyanates include compounds classified as potential human carcinogens and known to cause cancer in animals. The main effects of hazardous exposures are occupational asthma and other lung problems, as well as irritation of the eyes, nose, throat, and skin. [3]

Some isocyanates are also allergic sensitizers. Studies indicate that dermal exposure is a significant cause of respiratory sensitization. Thus, workers with skin contact to isocyanates may develop sensitivity, resulting in asthma attacks with subsequent exposures.

Sensitization can occur at very low levels of exposure and symptoms can continue for months or years after exposure has ceased. Deaths have occurred due to both asthma and hypersensitivity pneumonitis from isocyanate exposure. [4]

An ounce of prevention is worth a pound of cure

Preventing exposure to isocyanates is a critical step in eliminating the health hazard. The Center for Disease Control (CDC) recommends the use of engineering controls such as closed systems and ventilation as the principal method for minimizing isocyanate exposure in the workplace. Other controls, such as worker isolation and personal protective clothing and equipment may also be necessary. [6]

Engineering safety controls for reducing exposure

Sentry Air Systems line of source-capture fume extractors is suitable for most applications involving isocyanates. Our chemical and solvent fume extractors come in a variety of sizes and configurations. Our ductless spray booths are ideal for applications involving touch up paint or light spray painting. All of our units are equipped with high-quality filtration media capable of capturing sub-micron sized particles.

For more information on fume extraction solutions, contact Sentry today by visiting our website, calling 800.799.4609 or emailing us at