How to make a choice?? Since squishing my face into my mat (i.e. what I look like hovering in an attempted chaturanga... lol) happens when I practice, I would prefer if it didn't have lots of yummy toxic chemicals for my lungs to peruse. Also, eventually I will be old and brittle (and cranky!- well, unless I'll be one of those wild and who gives a f* grannies! WOOT) and my mat will have to retire. I'd prefer if it didn't hang out in the landfill to keep the plastic bags filled with plastic company.
We've covered rubber-natural rubber mats quite a bit here (check out the side-bar for links!) but I haven't really touched on the other, super eco-fraud out there "TPE".
Lululemon carries it, Gaiam carries it, Barefoot Yoga Company carries it... TPE or ThermoPLASTIC Elastomers, is used to make the latest ahem, "eco" mats that are cheap with increasing alacrity. But is it really a "green" option? Let's start with exactly what is TPE.
Thermoplastic Elastomers are made from... well it's hard to say. They are copolymers (which are two polymers, which are monomers put together... monomers are small molecules (any) that can bond together to form polymers... do you see how wonky this gets?) that are usually formed with plastic or rubber. Barefoot Yoga Company claims that it's TPE's are made from hydrogen and carbon... However, hydrocarbon (a monomer made from hydrogen and carbon) may consist of many different and not always eco-friendly (read: plastic) types. Also, Barefoot Yoga has a PER mat (polymer environmental resin). Rubber is considered an environmental resin... According to this site, PER (specifically yoga mats made from PER) is made from PVC. (WTF?) They add acetic try butyl citrate, liquid phased stabilizer, second mixture of powder like PVC, filling agent (whatever that is), light stabilizer uvasorb and fireproof agent (ummm)- baked at 170 degrees celcius and THEN becomes an environmental friendly resin. Riiiight. (http://www.appropedia.org/Polymer_Environmental-Friendly_Resin)
TPE's are PVC (Polyvinyl Chloride), latex, and (supposedly) rubber-free (when specified). Since the definition of what IS TPE is so vague, really it could be plastic+rubber=TADA! TPE. So the consumer really has to depend on the company to be upfront about what exactly their version of TPE consists of. Great, I really feel like depending on Lululemon to be upfront.
Another huge "eco-ability" these mats boast is their biodegradability. These mats do not, repeat, do not hold up well to sunlight or heat. I would know, mine started to break down after being exposed to the sunlight for about... 40 minutes. Now it flakes all over Andrew's pants. He likes purple flakes, they add to his yoga-zen. Unfortunately, as we discussed in my "bioplastic, really biodegradable?" post (see side bar for the whole post), this type of substance typically requires heat and sunlight to break down. Landfills aren't really the poster child for their beautiful sunlight views from the piles of plastic garbage bags. In fact, as opposed to "dumps" where garbage is continuously dumped (haha- clever), landfills are usually compacted and covered with soil daily. Soil isn't exactly a pristine, sunlight allowing window. I'm really not sure where the magical sunlight will penetrate the mounds of garbage bags and soil to break down the TPE yoga mat.
Now, you could also say, well why don't we just put our mats in the compost pile? Same reason, the mats will need prolonged periods of sunlight or heat to decompose, and unless you are 100% sure as to the purity of the "hydrogen and carbon" (or hydrocarbon) compounds that make up your mat, it may well be "biodegrading" into smaller pieces of it's chemical-y self. Into your soil. These mats are dyed to get their pretty colours and usually have glue (although Barefoot Yoga claims that their mats don't) to keep them together.
So my final conclusions? Thermoplastic Elastomer is a label that is a generic term and could mean pretty well anything from plastic to carbon. Overall it looks like a lot of greenwashing and still seems pretty darn synthetic. I choose natural rubber mats for their sustainability, reliability and performance. However, if you are a sensitive yogi/ni (the one who always is saying: "Do you SMELL that???") then rubber may not be for you. So far Barefoot Yoga Company is the most upfront and explanatory of the TPE crowd that I've found. :)
Hope this was helpful :)