I'm pretty sure they're around the bottom of the plastics chain and I've never seen any literature on recycling them.
I repurpose them for other things once they get runs or holes in them. They make good ties for staked plants in the garden. Put spools/shanks of yarn and rope in hose to keep them tidy and virtually knotless. Put a tube of wrapping paper in a knee-high instead of using a rubber band or piece of tape. Make your own no-sew satchets with potpourri or cotton balls soaked in essential oils/perfume. Use them as compost-tea bags. Use them as strainers for pools and water features. Stretch them over gutters in the fall to keep the leaves out. Use them to keep small craft items like buttons, beads and marbles tidy. Fill them with a little planting mix and use them as a hanging planter for seedlings or small plants. Get creative