I Googled "polymeric sand" and found this article:Polymeric Sand; What It Is and How To Use It
If you scroll down you'll find this paragraph:
Organic or Synthetic Binder for the Joint Sand?
The key ingredient in any binding paver joint sand is that ingredient that holds the sand together and in place in the joint. Some brands offer an organic binder in their joint sand while others manufacture a chemical binder to stabilize the sand. Installation is the same no matter which type you use, but the performance of the joint sand will differ depending on the binder used, so be sure you use the right sand for the right type of installation.
Organically-bound sands are made using the ground up bits of certain plants. It's that organic matter that acts as the glue for the sand, holding the sand particles together and holding them to the pavers, too. One of the major selling points to organic binder joint sands is also the source of it's greatest weakness; each time water is re-introduced to these sands they re-soften, "self-healing" in any locations where pavers may have shifted or settled and broken the bond with adjoining pavers. But in re-softening to the extent organically-bound joint sands do, they become far less able to resist the germination and growth of weed seeds. Further, the key ingredient in this type of sand, because it is organic, will break down over a period of time, requiring removal and re-application of fresh poly sand.
Those polymeric sands that use synthetic, chemical polymers look and feel virtually identical to their organic counterparts, but their properties differ in a few important ways. Where organic sands have the "self-healing" ability mentioned earlier, sands with man-made chemical binders do not (to any significant degree). The flip side of that is they are much better at resisting weed seed germination and growth, because they don't re-soften as organically-bound poly sands do. Because the chemical binder used is man-made, it does not break down in time like the organic paver sands do. Over time, this means better interlock for pavers, bluestone or even flagstone when chemical polymeric sands are utilized in segmental paver projects.
It looks like there is a chemical component to look into in the standard modern paver sands, and you should find out what those "parts of plants" are that are used in the eco version of the sand and choose from there.