Compostable and bio-based plastics (PHA, PLA)
Plastics made from plants or microbes that can break down under the right conditions. Useful for food-soiled items, but only where composting exists.
PHA, made by microbes, can biodegrade in soil and sea water under some conditions; PLA generally needs industrial composting. The honest test is local: if collected compostables go to landfill, the benefit disappears. Clear labelling and compost access matter as much as the material.