Methylenediphenyl diisocyanate (MDI) substances

Learn about methylenediphenyl diisocyanate (MDI) substances.

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About MDI substances

MDI substances don’t occur naturally in the environment. They’re industrial substances used to make polyurethanes and polyurethane products available to both industry and consumers.

Polyurethane and polyurethane products can be used to make items such as:

  • sealants
  • packaging wraps
  • paints and coatings
  • insulating products
  • foam slabs used in furniture
  • adhesives, including those used to make engineered wood products like wood panels

Some sealants available to consumers are known as spray polyurethane foam application products and have 2 separate chambers of chemicals in a kit. The chemicals in each chamber mix together to create the spray polyurethane foam, which is used to seal small cracks.

Safety of MDI substances

We assessed the potential health and environmental risks of 5 MDI substances through a chemical risk assessment. The assessment shows that use of MDI-based (for example, polyurethane) foam products with 2 chambers may pose a risk to your health. They may cause breathing problems and skin sensitivities.

What we’re doing

Canada is implementing a code of practice in partnership with industry and retailers to reduce exposures to MDIs.

The code sets out recommendations for actions that industry and retailers should take to inform Canadians about the safe use of these spray polyurethane foam application products.

What you can do

You can take action to minimize your exposure to MDI substances by:

  • following product instructions and safety warnings
  • having a work area with proper ventilation by:
    • working outside if possible
    • opening nearby windows
  • wearing clothing that covers skin to avoid getting the product on your skin
  • using proper safety equipment, such as a respirator designed to protect from MDI exposure, to avoid inhaling the substance

You may also choose to hire a professional contractor. Follow the contractor’s instructions on:

  • when to leave the area when it is not safe
  • when to re-enter the area when it is safe
  • how to keep the area well-ventilated and for how long

If you work with industrial substances, you may be exposed to MDIs. If this is a risk, you should consult with your employer and occupational health and safety (OHS) representatives about:

For more information

For industry and professionals

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