Polylactic Acid (PLA) plastic is a bioplastic often associated with sustainability. Its widespread use raises questions about its safety and potential toxicity.
Understanding PLA Plastic
Polylactic acid (PLA) is a plastic derived from renewable resources like corn, sugarcane, or cassava. This distinguishes PLA from traditional fossil fuel-based plastics. Its production involves fermenting plant sugars into lactic acid, then polymerizing it into long chains. This bio-based origin means PLA does not contain harmful chemicals often found in petroleum-based plastics, such as BPA or phthalates.
Assessing PLA’s Inherent Toxicity
PLA is generally considered non-toxic and biocompatible. This safety profile is a key reason for its widespread use in sensitive applications, such as dissolvable surgical sutures, drug delivery systems, and implants. When PLA degrades, it breaks down into lactic acid, a compound naturally found in the human body. The U.S. Food and Drug Administration (FDA) recognizes PLA materials as safe for use in medical applications and food packaging.
Factors Influencing PLA’s Safety in Specific Uses
While pure PLA is largely considered safe, commercial PLA products often contain additives influencing their safety. These additives, such as plasticizers, colorants, or stabilizers, may have different toxicity characteristics than the pure polymer itself. The safety concern often lies with these additives.
Temperature also plays a role in PLA’s behavior. High temperatures, such as from microwaving or hot liquids, can accelerate degradation. This process might lead to the leaching of additives or the release of volatile organic compounds (VOCs) and ultrafine particles (UFPs), depending on the specific formulation and conditions. Though PLA generally emits fewer VOCs and UFPs compared to many other plastics, proper ventilation is still advised during processes like 3D printing where heating occurs.
For food contact applications, PLA is broadly recognized as safe and is used in packaging, disposable tableware, and other food-related products. Regulatory bodies like the FDA and the European Food Safety Authority (EFSA) have established guidelines for PLA’s use in food contact materials. When used as intended and in compliance with these regulations, PLA is considered suitable for direct food contact.
Environmental Degradation and Byproducts
PLA is biodegradable, meaning it can break down into simpler, non-toxic compounds, but it typically requires specific conditions for efficient degradation. Industrial composting facilities provide the necessary high temperatures, humidity, and microbial activity for PLA to break down effectively. Under these controlled conditions, PLA can mineralize into lactic acid, carbon dioxide, and water within a few months, usually 45-90 days.
In contrast, PLA degrades very slowly in natural environments like landfills or oceans. Its crystalline structure requires specific conditions, including temperatures above 50-70°C, to initiate rapid biodegradation. This means that while PLA is biodegradable, it can persist for long periods in uncontrolled environments, potentially contributing to plastic pollution. However, the breakdown products, even if degradation is slow, are generally considered non-toxic.