The Hidden Chemical Challenge Behind the Global Push for Plastic Recycling

The global push to recycle plastic is accelerating, but a new OECD report highlights an uncomfortable truth: recycled plastics may carry hidden chemical risks. Developed with contributions from research partners such as Partners for Innovation and AIMPLAS, the study reveals that plastics are far more complex than they appear.

Rather than being simple materials, plastics can contain thousands of chemicals. Scientists estimate that over 13,000 substances may be present, including additives added during manufacturing and others formed unintentionally over time. Many of these chemicals are not fully understood, and thousands are not yet regulated. This creates a major challenge for ensuring that recycled plastics are safe to use.

Recycling Boom Meets a Complex Reality

Plastic production continues to grow rapidly worldwide, driven by rising demand across industries. Yet recycling has struggled to keep up. Only a small portion of plastic waste is currently recycled, and even future projections suggest recycled materials will make up a limited share of total use.

Recycling is often seen as a key solution to plastic pollution, but the report shows that it is not as straightforward as it seems. When plastics are recycled, they do not return to their original, clean state. Instead, they carry forward chemicals from their past uses, making each recycled batch unique and unpredictable.

How Plastics Collect Chemicals Over Time

The complexity begins early in plastic's life. Manufacturers add chemicals to improve flexibility, strength, colour, and durability. But plastics continue to pick up substances during use. For example, packaging can absorb food residues, cleaning agents, or other chemicals.

Once discarded, plastics enter waste streams where different materials are mixed. This leads to cross-contamination. During recycling, heat and processing can also create new chemical compounds.

By the time plastic is recycled, it may contain a mixture of original additives, contaminants from previous use, and new substances formed during processing. This layered chemical history makes it difficult to fully understand what is inside recycled materials.

Why Testing Is So Difficult

Detecting chemicals in recycled plastics is a major scientific challenge. Laboratories use advanced tools such as chromatography and mass spectrometry to identify substances, but no single method can detect everything. Experts must combine multiple techniques, and even then, some chemicals remain undetected.

Testing is also expensive and time-consuming. It requires specialised equipment and trained professionals, making it difficult to apply across large-scale recycling operations. As a result, many recyclers focus only on known or regulated chemicals, especially for products that do not require strict safety standards.

For high-risk uses such as food packaging or medical products, testing is more thorough. However, this creates uneven safety practices across the industry, depending on the final use of the recycled material.

Gaps in Rules and Global Challenges

One of the biggest concerns raised in the report is the lack of global standards. While some regions have strict rules for certain applications, there is no unified system to check the chemical safety of recycled plastics worldwide.

Most certification systems focus on tracking recycled content rather than analysing chemical composition. This means safety is often assumed rather than proven. At the same time, plastic waste is traded across borders, making it harder to track its origin and chemical makeup.

These gaps increase the risk that harmful substances could circulate through recycling systems without being detected.

Building Safer Recycling Systems

Despite these challenges, the report does not argue against recycling. Instead, it calls for a smarter and safer approach.

One key step is improving transparency so manufacturers clearly disclose the chemicals used in plastic products. Better tracking systems can help follow materials through their lifecycle. Designing plastics with fewer and safer chemicals can also make recycling easier and reduce risks.

The report also highlights the need for stronger international standards that include proper chemical testing. Investment in research and better testing technologies will be essential, as will closer collaboration between governments, scientists, and industry.

Recycling remains a critical tool in tackling plastic waste, but the message is clear. Without addressing chemical safety, the shift to a circular economy could create new risks while solving old ones. The future of plastics will depend not just on how much we recycle, but on how safely we do it.