Unfortunately, I think I read somewhere that the Polypropylene “green bags” aren’t really that green. Because the manufacturing process (done in china) isn’t really that clean to make these. At one point in time, we did some research on this and even had a supplier lined up china to mass produce these as promotional items. I suppose the idea is that these last longer than normal plastic bag, so that you won’t go through them as quickly. But they also fall apart pretty quickly. If you take a iron or for that matter moderate heat to one of those bags, it will melt and disintegrate into a hard crusty plastic.. (Tried to do a heat press on the bags..Didn’t work)
Using natural material like cotton/polyester, though is a different category.