Plastic Waste: Recycling ≠ Utilization

Considering the climate crisis and global plastic pollution, many people believe that recycling materials, especially plastics, is the solution to plastic pollution. Recycling can reduce resource usage, prevent waste, and decrease carbon dioxide emissions. It is an important foundation of circular economy. The recycling of some materials is relatively simple, but the recycling of plastics involves complex target conflicts.

Recycling fossil based plastics is particularly important compared to burning them (heat recovery) or dumping them into the environment after one use. In many cities in Switzerland, plastic waste, or more accurately, mixed household plastics, can be collected in plastic bags and then sorted and recycled using machines.

However, the recycling process will soon reach its limit. From an environmental perspective, mechanical recycling is most useful when recycled materials replace native materials as much as possible. This means that carbon dioxide emissions during production and incineration can be avoided, and plastics will not enter landfills or the environment. However, replacing new plastics requires high-quality recycled materials, which is precisely the problem.

Chemical substances can disrupt the recycling process

There are various types of plastics produced and used, which are composed of polymer chains made up of repeated monomer units. Depending on the application, these polymer chains also contain many additional chemicals, including stabilizers, plasticizers, and flame retardants, which give plastics the necessary characteristics. In a report written for the United Nations Environment Programme, researchers found that up to 13000 chemicals are used in plastics. Many of these substances may be harmful to human health and the environment. However, in some cases, these substances have not been adequately regulated.

A large amount of plastic and additives often reduce the quality of recycled materials and make recycling difficult or impossible in practice. Therefore, if many plastic products cannot be made from recycled materials and can only be made from new materials, collecting more and more plastic waste will not be of much help to us.

A more serious issue is that long-lasting plastic products often contain additives, which we now know are harmful to human health and the environment. If the recycling of these plastics is not carefully managed, it may lead to regulated chemicals circulating in the market for longer periods of time rather than being removed from the cycle.

The drawbacks of colorful plastics

Unlike food, plastic manufacturers rarely need to disclose their formulas and ingredients. This means that people do not know what ingredients most plastic products contain, nor do they know if they can be safely recycled. The purpose of this study is to attempt to determine what materials plastics are made of and whether they can be recycled.

For example, as part of a study published in the journal Environmental Science and Technology, researchers recently collaborated with colleagues from other universities in Switzerland to investigate plastic floor coverings made of polyvinyl chloride (PVC). Polyvinyl chloride is an important plastic in the construction industry and is often recycled (recycling rate: 16%). In this study, the research team tested 151 new PVC flooring products purchased in Switzerland for heavy metals, plasticizers, and other chemicals.

The research results are surprising. Harmful additives that have long been banned were found in 24 (16%) new floor coverings, such as lead used as a stabilizer and plasticizer DEHP (a phthalate). Due to the health hazards, the European Union and Switzerland have banned the use of lead and DEHP in new materials. Therefore, researchers believe that these substances can still be found in new flooring, possibly due to contamination of recycled

polyvinyl chloride.

Another 29% of floor coverings contain other phthalate plasticizers, which are still approved for use but still cause concern. Some phthalates are suspected to have endocrine disrupting and carcinogenic effects, and are associated with various diseases.
People have always believed that polyvinyl chloride flooring is the main source of harmful chemicals inside buildings because they release plasticizers. But in fact, people still know very little about its chemical composition.

How to solve this problem?

This example illustrates that plastics contain a wide variety of chemicals and lack transparency, which not only poses problems for the circular economy but also poses a danger to humans and the environment.
In the future, it is necessary to find sustainable ways to recycle PVC flooring materials without causing harm to human health. This requires stricter control and processes to remove harmful chemicals from recycled PVC products. Practical methods for detecting phthalate plasticizers in plastics have been developed, and these methods need to be incorporated into the recycling system.

But for other chemical substances, there is currently no fast and simple detection method. In this case, researchers believe that rapid and simple analysis of other types of plastics and chemicals is still needed, especially with adjustments to production processes.

If more new materials need to be replaced in the future, higher quality recycled materials will be needed. In practice, this mainly means reducing the amount of different plastics and chemicals used, adopting more standardized material design methods, considering recycling from the beginning, and improving the transparency of the supply