If you’re adding green to your closet by way of bamboo-fabric garments, hold up.

Although of natural, renewable origin, “bamboo textiles are essentially rayon, wood that is (chemically) liquified and extruded into a filament, then spun into thread and knit or woven into fabric,” explains Lorraine Smith, a Toronto-based sustainability consultant.

In the U.S., the Federal Trade Commission recently charged four companies for making falsely green claims regarding bamboo-fabric products, and declared that “bamboo-based textiles, actually made of rayon, are not antimicrobial, made in an environmentally friendly manner, nor biodegradable.”

In Canada, as of Sept. 1 textile dealers must label bamboo-derived fabrics as rayon, rayon from bamboo or other terms depending on the chemical process to create it. The exception is bamboo linen, which is mechanically processed in a way similar to linen made from flax.

“Knowing the difference between bamboo rayon and bamboo linen is important,” says Kelly Drennen, president of Fashion Takes Action, an industry sustainability education and resource group. “There’s a difference between knowingly ‘green washing’ and coming by it honestly. I think many bamboo-based businesses had no idea how the fabric is made, or that it really isn’t eco-friendly.”

The new labelling rules are a positive move, say both Smith and Drennen. “It’s always a good thing when people know more about where stuff comes from,” says Smith.

As to biodegradability, Smith doesn’t see it as a true measure of green. “To suggest biodegradability is an ‘eco-friendly’ attribute suggests that once the consumer is done with it they can just hang it outside on their hedge for a while and it will gently merge with the natural world,” she points out. “Of course that’s not how it works. Non-biodegradability is a more eco-friendly aspect if it means the item can be recycled more effectively.”