Mohawk’s Corn-Based Carpets

September 21, 2010, by Debra Lynn Dadd

Question from Gary

Anyone know if these carpets off-gas less or more healthily than petroleum based carpets?

Debra's Answer

These carpets are made from propanediol, or Bio-PDO, a corn-based polymer. It is made from corn sugar, a by-product of making ethanol, generated at a nearby plant. An E. coli bacteria --genetically-modified by DuPont scientists--breaks down the corn sugar through a fermentation process that is much like making beer.

Mohawk is now selling a carpet made from this fiber called SmartStrand.

The SmartStrand website tells all the environmental savings that comes from using Bio-PDO, but also says that only 37% of the carpet is Bio-PDO. So I called Mohawk and found out that the other 63% is polyester. And it contains no stain resistant treatments because the polymer is "naturally" stain resistant. Hmmmm, I've never heard of a natural fiber being inherently stain resistant.

While this is anecdotal, several readers have commented that it has a strong odor that does not dissipate quickly. Odor is not reliable for determining if chemicals are off-gassing but it is an indicator.

Updated 2019: Here is another related question:

Question from Donna

We are replacing the carpet in all of our bedrooms, which adds up to over 1200 sq. ft.  We've priced out wool carpet and padding, and it is very expensive.  (I don't want hardwood flooring upstairs in the bedrooms for several reasons.)  A vendor is recommending Air.O carpet by Mohawk, which is supposed to be VOC and odor free and is carpet and padding in one.  It's also supposed to be hypoallergenic and made of 100% PET.  They have stated there are no flame retardants in the backing.  Have you heard of this carpet and what would you think of it as a more economical option?  Thank you!

Lisa’s Answer

This is a great example of a product with a second-party certification, which means it is certified by an industry association affiliated with the products it tests.  In this case, the The Carpet and Rug Institute, a  carpet industry association has come up with its own certification called the Green Label Plus Indoor Air Quality Standard.  Keep in minded, it has a vested interest in certifying as many rugs and carpets as possible to earn revenue and sell more products.  On its website it actually states that, "the carpet industry has a long history of creating products that provide numerous benefits, especially for indoor air quality."  In fact, carpets are a know source of VOC emissions.

It is difficult to understand the criteria for certification based on the information provided on the website, however, it does comply with California's Collaborative for High Performance Schools (CHPS) low-emitting materials criteria, which are fairly rigorous.  The claim that it is VOC free most likely means that it has VOC emission, but the levels fall below a certain standardl.

Without more specific information, I would assume that this is a better choice than other synthetic wall-to-wall carpets but not as safe as one made of natural materials.  Understanding cost is an issue, I would ask the company these additional questions.

What is the level ( in parts per million) of formaldehyde emissions?

Is the entire product free of flame retardants or just the backing?

Are chromium dyes used in the carpeting?