Polylactic acid (PLA) is a biopolymer and a repeating chain of lactic acid, which undergoes a 2-step degradation process. 1. DISINTEGRATION : The moisture and heat in the compost pile split the polymer chains apart, creating smaller polymers, and finally, lactic acid. 2. BIODEGRADATION : Microorganisms in compost and soil consume the smaller polymer fragments and lactic acid as nutrients. Since lactic acid is widely found in nature, a large number of organisms metabolize lactic acid. The end result of composting is carbon dioxide, water and humus, a soil nutrient. This degradation process is temperature and humidity dependent.