PLA is classified as a “thermoplastic”. Thermoplastic materials become liquid at their melting point (150-160 degrees Celsius in the case of PLA) which allows them to be easily injection molded (lids/cups/cutlery) or sprayed (container lining). In its solid form, PLA is not toxic. As PLA is biodegradable, it is often used in food handling and medical implants that biodegrade within the body over time.
Using PLA eliminates the need to use non-renewable and unsustainable petroleum resources. Like most plastics, during the manufacturing process it has the potential to be toxic if inhaled and/or absorbed into the skin or eyes as a vapor or liquid. PLA is fairly unsuitable for very high temperature applications (such as reheating in a microwave). It has been approved for use in manufacture of disposable products as the temperatures of any hot drinks or food have to be safe for humans, to avoid scalding.