oyster mushrooms grown in polyester

So about a month ago, I experimented with putting some oyster mushroom spawn in some old clothing of mine. Some of it was 100% cotton, while others were cotton/synthetic blends -- either polyester or rayon or spandex. Surprisingly, nearly all of them have fruited. So my question is, are the ones borne of synthetic blends going to be safe to eat?

As long as there are no heavy metals or radio active elements involved, my guess is the fruits are safe to eat.
The long molecule chains of the synthetics get broken apart and rebuild by enzymes into molecules need by the mushroom. If this process was not equivalent to say decomposing lignin or cellulose then the mushroom itself would be in big trouble.

Cool, thanks! I'm curious what effect this would have on the decomposition timeline of the synthetics? I know the 100% cotton stuff can be thrown right in the compost pile once its been exhausted, but I wonder about the blends

Well rayon is cellulose so should be broken down by the mushrooms like the cotton but the others I don't know what will be left. It all depends on the enzymes the mushroom produces and I read that suggests the mushroom can be trained to feed on different materials.