Pinnacle West Tech Tips

WORKING WITH
POLYMERIC MDI

This tech tip focuses on the important health and safety aspects of working with Polymeric MDI. It covers the hazards associated with Polymeric MDI and ways to reduce exposure. This guide is not a substitute for the information contained in a products Safety Data Sheet (SDS).

|| WHAT IS IT?

Methylene diphenyl diisocyanate (MDI) is an aromatic diisocyanate, this isomer is also known as Pure MDI. Polymeric MDI (A-side) is a mixture of monomeric diisocyanate MDI and higher molecular weight forms of MDI that typically are reacted with a polyol (B-side) to produce polyurethane foam. Other MDI-based products also can be reacted with a polyol and/or an amine in the production of elastomers, coatings, adhesives, or sealants. Throughout this guide, the term MDI is used to address both MDI and polymeric MDI.

|| POTENTIAL HAZARDS

Overexposure to airborne MDI can occur in inadequately ventilated environments when MDI is sprayed, aerosolized, or heated. In addition, overexposure can occur when there is direct skin contact with liquid MDI.

Applicators, helpers and other personnel may be exposed to MDI during:

Handling of chemicals.
The spray application.
Jobsite cleanup.
Equipment maintenance.
Spill cleanup.

There are four possible routes of exposure:

Breathing it in.
Getting it in your eyes.
Getting it on your skin.
Swallowing it.

Here are the potential effects of overexposure and some first-aid considerations:

Inhalation: If MDI is sprayed as a mist or heated, or handled where there is poor ventilation, there is a greater chance of overexposure. Even if you cannot smell MDI, you may be in danger of overexposure.

MDI can irritate your nose and lungs. You may feel tightness in your chest and have difficulty breathing. Overexposure may cause you to become sensitized or allergic to MDI which may cause you to have asthma-like attacks if you breathe MDI vapors again. If this happens, any further exposure must be avoided. Effects may occur immediately upon exposure, and/or be delayed for several hours after exposure ends.

If you suspect someone has become overexposed, remove the person to an area with fresh air, and try to keep them calm and warm - but not hot. Seek immediate medical attention. If they are having difficulty breathing, a qualified person may provide oxygen. If they stop breathing, a qualified person may give artificial resuscitation.

Eye Contact: Getting MDI in your eyes can be painful and could cause tearing and irritation. If you get MDI in your eyes, wash them immediately with a continuous flow of low pressure water, preferably from an eyewash fountain, for at least 15 minutes. Seek medical attention at once.

Skin Contact: Getting MDI on your skin may play a role in the development of skin sensitization. In addition, animal tests have indicated that respiratory sensitization may occur from skin contact with MDI. Repeatedly getting MDI on your skin may also cause discoloration, redness, swelling, or itching. To protect skin, wear personal protective equipment (PPE) in such a manner as to protect all skin (there should be no exposed skin showing).

It is best to conduct your work to avoid skin contact, but if you get MDI on your skin, wash thoroughly with soap and flowing water (warm water if available), do not use solvents.

If your skin is irritated, seek medical attention. Properly dispose of any clothing contaminated with MDI, as well as contaminated items such as shoes, belts, and watchbands.

Ingestion: Swallowing MDI can cause irritation in your mouth, throat and stomach. If you swallow MDI, rinse the mouth with water; do not try to induce vomiting. Seek medical attention at once.

|| PROTECTING YOURSELF

Overexposure to MDI liquid, vapor or aerosol can be harmful to your health. The following sections describe the types of PPE required when working with MDI.

1: Where there is a risk of direct skin and eye contact with liquid MDI consider using at a minimum:

MDI-resistant gloves.
Chemical safety goggles and/or face shield.
MDI-resistant long-sleeve coveralls.
MDI-resistant boots.

2: For tasks that do not involve spraying (such as cleaning equipment), but where you may have contact with heated MDI add the following to items listed in section 1:

A NIOSH-approved air purifying respirator (APR) with combination Organic Vapor / P100 cartridges.

3: During spray application where there is a risk of exposure to airborne MDI, add the following to items listed in section 1:

A NIOSH-approved supplied air respirator (SAR). SARs provide a supply of breathing air from an outside source such as a compressor or a low pressure pump attached to an air-line hose.

Visit spraypolyurethane.org for additional health and safety information.

This guide is not intended to provide specific technical advice. All persons involved in handling MDI should consult the appropriate sources of safety and handling information, including product labels, technical data sheets, SDSs, and other literature.

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