Isocyanates technical fact sheet

Isocyanates are a group of highly reactive organic compounds that can easily become volatile and enter the atmosphere as a vapour. They are common components in the production of polyurethane foams and 2-pack spray coatings used to provide a protective coating over a range of materials including cement, wood, fiberglass, steel and aluminium.

Adequate controls for the proper use, handling and storage of isocyanate containing materials reduce the risk of hazardous exposures and illness in the workplace.

The NSW Work Health and Safety (WHS) Roadmap states a target of a 50% reduction in serious injuries and illnesses by 2022, including a reduction in exposures to the priority hazardous chemicals and materials by 30%. An initial list of 100 priority chemicals was developed based on national and international sources. This list was further refined using the following criteria: toxicity rating, exposure potential, estimated quantities used and potential number of workers using these chemicals. Isocyanates ranked seventh based on these criteria.

Print this page in pdf.

Sources of exposure

Isocyanates are used in manufactured materials including polyurethane foams, synthetic rubbers, coatings (including paints and varnishes), elastomers and plastics. Exposure to isocyanates most commonly occurs through inhalation of aerosols, mists, dusts or vapours.

Occupations that are most at risk of exposure to isocyanates include:

  • spray painting/coating
  • auto industry (repair, manufacture and finishing)
  • building installations
  • manufacturing of synthetic rubbers, polyurethane foams, plastics and insulation.

Heating isocyanate containing materials is likely to release isocyanates into the atmosphere. Activities such as hot wire cutting foams, welding through polyurethane pipe lagging, high temperature bonding using polyurethane sealants and hot removal of varnishes are activities that may lead to inhalation exposure to isocyanates. Sanding isocyanate containing materials such as paints, foams and plastics may also result in inhalation exposure from dust particles.

Health effects

Isocyanates are a powerful irritant to the mucous membranes of the eyes and gastrointestinal and respiratory tracts. Acute (short-term) inhalation exposure to isocyanates can result in irritation of the nose, throat and eyes, irritation to the respiratory system including coughing, wheezing and shortness of breath, gastrointestinal distress such as nausea and vomiting, and headaches. Direct contact with the skin or eyes can result in contact conjunctivitis, blistering, swelling and irritation.

Sensitisation can occur after high acute exposure, or prolonged exposure to lower concentrations of isocyanates. Sensitised workers may suffer allergic reactions including occupational asthma, dermatitis, hives and rashes at very low, or brief exposure to isocyanates.

In addition to immune sensitisation, chronic exposure to isocyanates may cause liver and kidney disease, chronic lung damage and cancer. Isocyanates listed as suspected of causing cancer include:

  • 4,4'-methylene diphenyl diisocyanate
  • 2,2'-methylene diphenyl diisocyanate
  • o-(p-isocyanatobenzyl)phenyl isocyanate
  • methylene diphenyl diisocyanate (MDI)
  • toluene-2,4-diisocyanate
  • toluene-2,6-diisocyanate
  • toluene diisocyanate (TDI)

Labelling and safety data sheets

Manufacturers and importers of chemicals containing isocyanates need to ensure they are labelled and that safety data sheets (SDS) are prepared and provided (cl.330 and 335 Work Health and Safety WHS Regulation 2017). Suppliers of a material containing a hazardous chemical to a workplace must provide current SDS (cl.339).

Persons conducting a business or undertaking (PCBUs) must correctly label hazardous chemicals used, handled or stored at the workplace, including materials, containers and pipework (cl. 341,342,343). The PCBU must also obtain a copy of the SDS and make it readily accessible to workers involved in using, handling or storing the hazardous chemical at the workplace (cl. 344).

Workplace exposure standards and air monitoring

According to the Work Health and Safety Regulation 2017, a business must ensure that a worker is not exposed to airborne chemicals above the workplace exposure standard. Isocyanates have a workplace exposure standard of 0.02 mg/m3 averaged over eight hours and a short term exposure standard of 0.07 mg/m3 averaged over 15 minutes. Isocyanates are classified as a sensitiser and some individual isocyanates are further classified as suspected of causing cancer.

Risks to health and safety from exposures to hazardous chemicals must, so far as is reasonably practicable, be eliminated (cl. 35). Where elimination is not practicable, PCBUs must ensure that no person at the workplace is exposed to a substance above its exposure standard (cl. 49) and must reduce exposures so far as is reasonably practicable.

Where it is uncertain (on reasonable grounds) as to whether or not the exposure standard is exceeded, PCBUs must undertake exposure (air) monitoring for substances with an exposure standard (cl. 50). Adjustments to the exposure standards are made for extended work shifts, taking into account the longer daily exposure. The air monitoring results must be readily available to workers and records of results must be kept for 30 years (cl. 50).

A PCBU must review control measures (cl. 352):

  • when the workplace exposure standard for a hazardous chemical has been exceeded
  • if a health monitoring report contains advice a worker may have contracted an illness/disease, or a recommendation for remedial measures including whether a worker can continue to work with the hazardous chemical
  • the SDS for the hazardous chemical changes.

Health monitoring

Isocyanates are listed in schedule 14 of the Work Health and Safety Regulation 2017. PCBUs are required to provide health monitoring to workers if there is a significant risk to the worker’s health because of exposure to a hazardous chemical listed in schedule 14 of the Work Health and Safety Regulation 2017 (cl. 368).

In relation to health monitoring, PCBU (cl. 369 to 378) duties include:

  • informing workers of the requirements for health monitoring
  • using a registered medical practitioner with experience in occupational health monitoring
  • providing details to the medical practitioner
  • obtaining a copy of the health monitoring report
  • providing a copy of the health monitoring report to SafeWork NSW if the worker has developed a disease or injury and/or the report contains any recommendations on remedial measures at the workplace
  • keeping records of health monitoring for 30 years.

As per schedule 14, health monitoring for isocyanates consists of a respiratory work up. However, biological monitoring, with strategically timed urine analysis can be a beneficial tool to assess the effectiveness of controls in the workplace in a more timely manner.

Control measures

Where risks to health and safety cannot be eliminated the hierarchy of controls must be applied in accordance with cl. 36 of the Work Health and Safety Regulation 2017 to minimise risks. For instance:

  • Where practicable, substitute isocyanate containing or liberating products with an alternate material.
  • Ensure adequate engineering controls (e.g. local exhaust ventilation, automated processes or spray booths) are in place.
  • Use appropriate tools or personal protective equipment to avoid skin contact with isocyanate containing chemicals.
  • Use well maintained and appropriate personal protective equipment (PPE) such as full-face respirators, overalls, safety goggles and chemical-resistant gloves including a program to correctly fit, instruct on the use and ensure regular maintenance of PPE.
  • Ensure safety equipment is available (e.g. eye wash and showers).

Ensure that instructions and controls outlined in SDS and product labels are followed and that workers are provided with suitable information, training, instruction and supervision when using, storing and handling hazardous chemicals (cl. 39 and 379).

PCBUs with duties under the Work Health and Safety Regulation 2017 must review and revise control measures, as necessary, to maintain a work environment so far as is reasonably practicable, that is without risk to health or safety (cl. 38).

More information

More information is contained in:

In the event of suspected exposure, call the Poisons Information Centre on 131 126

Back to top