The question “Are Plastics Biodegradable” is a complex one, sparking much debate and confusion. While the promise of plastics that naturally break down seems appealing, the reality is far more nuanced. This article will delve into the heart of the matter, exploring the different types of plastics, the conditions required for biodegradation, and the true impact of biodegradable plastics on our environment.
Unpacking Biodegradability What Does it Really Mean?
The term “biodegradable” often conjures up images of plastic items disappearing harmlessly back into nature. However, true biodegradability is a specific process. It refers to the breakdown of materials by microorganisms – bacteria, fungi, and algae – into natural substances like water, carbon dioxide, and biomass. This process requires specific environmental conditions, such as temperature, humidity, and the presence of these microorganisms. Understanding the intricacies of biodegradation is crucial to correctly interpreting if plastics are biodegradable and how to best handle plastic waste.
Many conventional plastics are derived from petroleum and are not biodegradable. These plastics are made of long chains of molecules called polymers that microorganisms simply cannot break down efficiently, if at all. This resistance to degradation is what makes them so durable, but it also leads to their accumulation in landfills and natural environments. The lack of biodegradability of these conventional plastics has resulted in severe environmental problems, as their persistence in the ecosystem leads to pollution and harms wildlife.
There are a few key factors to consider when assessing if a material is truly biodegradable:
- The material’s chemical composition: Is it made of substances that microorganisms can consume?
- The environmental conditions: Are the necessary microbes, temperature, and moisture present?
- The timeframe: How long does it take for the material to completely break down?
Biodegradable Plastics A Closer Look
While conventional plastics are not biodegradable, some plastics are designed to break down under specific conditions. These “biodegradable plastics” are often made from renewable resources, such as corn starch or sugarcane, or from petroleum with additives that enhance their biodegradability. However, it’s important to note that the term “biodegradable” can be misleading. Many biodegradable plastics only break down in industrial composting facilities, where high temperatures and specific microbial conditions are carefully controlled.
There are different types of biodegradable plastics, each with its own characteristics and limitations:
- PLA (Polylactic Acid): Made from corn starch or sugarcane, PLA is commonly used in food packaging and disposable tableware. It is biodegradable under industrial composting conditions.
- PHA (Polyhydroxyalkanoates): Produced by microorganisms, PHAs are biodegradable in a wider range of environments, including soil and marine environments.
- PBS (Polybutylene Succinate): A petroleum-based plastic with added biodegradable components, PBS can degrade under certain conditions.
The following table summarizes a few common types of biodegradable plastics and their degradation requirements.
| Plastic Type | Material Source | Biodegradation Conditions |
|---|---|---|
| PLA | Corn Starch, Sugarcane | Industrial Composting |
| PHA | Microorganisms | Soil, Marine, Industrial Composting |
| PBS | Petroleum with Additives | Specific Conditions |
The Reality of Biodegradability in the Real World
Even if a plastic is labeled as “biodegradable,” it doesn’t automatically mean it will break down quickly and easily in a landfill or in your backyard compost bin. Many biodegradable plastics require the controlled conditions of industrial composting facilities, which are not widely available. If these plastics end up in landfills, where oxygen is limited, they may not degrade at all. It’s crucial to consider the entire lifecycle of a biodegradable plastic, from production to disposal, to understand its true environmental impact.
Moreover, the term biodegradable does not mean the plastic is compostable in your home compost. At home, you might not have the correct mixture of bacteria, fungi, algae, temperature, and humidity to break down the plastics. If you put a plastic item in your home compost bin, it may take years or decades to fully decompose.
In addition, some plastics claim to be “oxo-biodegradable.” These plastics are conventional plastics with additives that cause them to break down into smaller fragments. However, these fragments are still plastic and do not fully biodegrade into harmless substances. There is increasing scientific evidence that oxo-degradable plastics do not offer environmental benefit, and may contribute to microplastic pollution.
For more detailed technical information on biodegradable plastics, the Ellen MacArthur Foundation has an excellent resource that we encourage you to review.