The tiny stickers found on fresh produce, carrying Price Look-Up (PLU) codes, are a ubiquitous part of modern grocery shopping. As consumers divert organic waste from landfills, the question of whether these small labels can be tossed into a compost bin has become common. The simple answer is that the vast majority of these stickers are not compostable, though this is beginning to change. Understanding the materials and the strict definitions of compostability is necessary to grasp why they pose a problem for composting facilities.
What Standard Produce Stickers Are Made Of
The primary purpose of a standard PLU sticker is durability and adherence throughout the supply chain, often involving moisture and temperature changes. These functional requirements dictate the materials used in their construction. A typical sticker is composed of three layers: the face stock, the adhesive, and the backing liner, though only the first two remain on the produce.
The face stock, the visible top layer carrying the printed code, is most often a synthetic film. Common materials include various forms of plastic like vinyl, polyethylene (PE), or polypropylene (PP). These petroleum-based films are chosen because they are water-resistant and flexible enough to conform to the curved surfaces of fruits and vegetables. This ensures the sticker remains intact from the farm to the checkout counter, but it means the face stock is non-compostable plastic.
The second layer, the adhesive, is also a synthetic material, typically a rubber or acrylic-based pressure-sensitive glue. This adhesive needs to be strong enough to stick to the produce through washing and handling. Standard adhesives are designed for performance and longevity, not for biological breakdown, meaning they will persist in a composting environment. The combination of a plastic film and a synthetic glue prevents most produce stickers from breaking down alongside organic waste.
What Defines a Compostable Product
The terms “biodegradable” and “compostable” are often confused, but they have distinct, regulated definitions in the context of commercial waste processing. A product labeled “biodegradable” simply means it will eventually decompose into natural elements. However, this process can take years and has no defined timeline or required environmental conditions.
In contrast, a product must meet stringent criteria to be certified as “compostable.” This means the material must break down completely into carbon dioxide, water, inorganic compounds, and biomass within a specific timeframe, typically 12 weeks or 90 days. The process must leave no toxic residue, and the resulting material must be able to support plant life.
In the United States, the primary specification for commercial compostability is the American Society for Testing and Materials (ASTM) D6400. This standard requires that the product disintegrate into small pieces, with less than 10% visible residue remaining after 12 weeks. Furthermore, 90% of the organic carbon must convert into CO2 within 180 days. These conditions mimic the high heat and controlled environment of industrial composting facilities, where temperatures can reach 131°F to 158°F (55°C to 70°C).
Environmental Impact of Non-Compostable Stickers
When standard, non-certified produce stickers enter the organic waste stream, they become a source of contamination that degrades the quality of the final compost. Consumers often toss the stickers along with the fruit peelings into food waste bins, where they are collected and sent to commercial composting facilities. Because the stickers are made of plastic film and synthetic adhesive, they fail to break down under the high heat and microbial action of the composting process.
Their small size is a major contributor to the problem, as it allows them to easily slip through the screens and sorting equipment designed to filter out larger contaminants. The plastic film fragments into smaller pieces that remain in the finished compost. These tiny plastic remnants are a form of microplastic pollution that is then spread onto agricultural land when the compost is used as a soil amendment.
The presence of non-compostable stickers creates significant operational challenges and financial burdens for composting facilities. High contamination levels can lead to batches of food waste being rejected entirely and diverted to a landfill. Even processed waste is visually and chemically contaminated, making it difficult to sell or use, and increasing overall processing costs.
How to Identify Certified Compostable Alternatives
A growing number of growers and retailers are transitioning to truly compostable produce stickers to address the contamination issue. These certified alternatives are constructed from materials specifically designed to meet industrial composting standards.
Materials Used in Alternatives
The face stock of certified stickers is often made from renewable resources like cellulose, plant-based starches, or specialized papers. The adhesive is typically a natural, compostable rubber or polymer. These materials are specifically designed to meet industrial composting standards.
Certification Marks
Consumers should look for specific certification logos from recognized third-party organizations. The most common certifications include:
- The Biodegradable Products Institute (BPI) certification mark, which indicates compliance with the ASTM D6400 standard for industrial composting in North America.
- TÜV AUSTRIA OK compost INDUSTRIAL marks.
- TÜV AUSTRIA OK compost HOME marks.
These marks denote compliance with recognized composting standards.
Consumer Responsibility
If a sticker does not carry one of these clear certification logos, consumers should assume it is a standard non-compostable plastic and adhesive combination. The most responsible action is to peel the sticker off the produce and dispose of it in the regular trash before composting the scraps. Consistent effort by consumers to separate these non-compostable materials prevents large-scale microplastic contamination of the compost stream.