PLA is a polyester made by fermenting corn or sugarcane sugars into lactic acid and then polymerising it. It is clear, stiff and runs on standard thermoforming and injection-moulding lines, which is why it is the most widely used bio-based, biodegradable plastic.
It replaces clear cold-drink cups and lids, clamshells, cutlery, tea bags, coffee-capsule bodies, films, fibres and 3D-printing filament, where it is the dominant desktop material. The main producers are NatureWorks (Ingeo) and TotalEnergies Corbion (Luminy).
End of life is the problem. PLA is certified for industrial composting only (EN 13432, ASTM D6400), which needs about 58 degrees C. It does not break down in home compost, soil or the sea in any useful timeframe, and University College London (UCL)'s Big Compost Experiment (902 UK households, Frontiers in Sustainability, 2022) found that 60 percent of items carrying even a home-compostable mark were still clearly visible after home composting. Clear PLA cups and containers look like PET, so they can end up in PET recycling, where they contaminate the batch. On carbon, TotalEnergies Corbion's 2025 life-cycle assessment (LCA) claims up to 85 percent lower footprint than conventional plastics. But this is the seller's own study. It covers only making the resin, not use or disposal, and it credits PLA for the carbon the crops absorbed while growing. A NatureWorks-commissioned study (HYDRA) argues PLA does not form lasting microplastics because it slowly breaks down in water.
Drawbacks: most consumers have no access to industrial composting, so PLA cups usually go to landfill where they can emit methane; it deforms above about 55 degrees C; feedstock competes with food and land, though European Bioplastics, the industry's trade body, estimates bioplastics use under 0.02 percent of agricultural land. Cost: resin at US$2.8 to 3.5 a kg against US$1.2 to 1.4 for PET, roughly two to three times.