The Toxicity of Polyurethane

November 22, 2010, by Debra Lynn Dadd

I just happened to receive two questions this week about the toxicity of polyurethane, so I thought I would write a separate post on this chemical.

In the past, we mostly heard about polyurethane foam, which is used to make mattresses, seat cushions, and other such products. That likely contains toxic chemicals.

Now, there are new products that have a thin polyurethane film fused to fabric to make it waterproof. As best as I can tell, this is made from a different type of polyurethane, probably the type that is used to produce FDA dry and wet food grade urethanes.

Here's the chemistry lesson.

Polyurethane (or "urethane" for short) is the name given to a class of petrochemical resins that contain isocyanates.

There are three different polyurethanes:
1. Toluene Diisocyante (TDI)
2. Diphenylmethane Diisocyanate (MDI)
3. Paraphenylene Diisocyanate (PPDI)

And they are made into chemicals that fall into eight major groups:

1. MDI-Esters: produce FDA dry and wet food grade urethanes.
2. TDI-Esters
3. MDI-Ethers: Some are adaptable to FDA and USDA application for wet and dry food contact.
4. TDI-Ethers
5. PPDI-Esters
6. MDI
7. TDI: used to make polyurethane foam for mattresses, cushions etc
8. PPDI

So when you read that something is made from "polyurethane" you need to also find out what type of polyurethane it is.

It's likely that the MDI food grade polyurethane is a lot less toxic than the TDI polyurethane foam. To research the health effects of every polyurethane is beyond the scope of this blog at the moment. But I've done enough research to see that the toxicity of one "polyurethane" is different than another. It's unfortunate that the same word is used to refer to a whole class of chemicals of varying toxicity.

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