Methylenediphenyl diisocyanate (MDI) substances

Learn about methylenediphenyl diisocyanate (MDI) substances and if they’re safe.

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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.

These products include:

  • coatings
  • insulation foams
  • packaging wraps
  • foam slabs used in furniture
  • adhesives, such as those used to make engineered wood products like wood panels

MDI substances are also used in adhesive, sealant and insulating products available to consumers.

Some spray polyurethane foam application products have 2 separate chambers of chemicals in a kit. The chemicals in each chamber mix together to create the spray polyurethane foam.

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 products with 2 chambers may pose a risk to your health. They may cause breathing problems and skin sensitivities.

Ongoing protective measures

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

This would involve setting out recommendations about the safe use of certain spray polyurethane foam application products.

Minimize your exposure to MDI substances

You can minimize your exposure to MDI substances.

If using the product yourself:

  • follow safety warnings and label directions
  • prepare the work area to obtain proper ventilation
  • wear protective clothing to avoid getting the product on your skin
  • use safety equipment, such as a respirator, to avoid inhaling the substance

If hiring 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:

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For industry and professionals

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