According to the EU's circular economy strategy, from 2030 onwards, all plastic packaging placed on the market must be recyclable or made from recycled material. The recycling of PET bottles is already well established on the market in contrast to that of polyolefins and polystyrene (PS), whose use in contact with food is considered problematic. Currently, any unknown substance is automatically classified as a concern. The aim of the SafeCycle research project is to clarify the origin of any contaminants and to initiate appropriate preventive measures. The project consortium of SafeCycle consists of three scientific partners, about 30 companies from Austria, 40 companies from Germany, and eight international companies. These are recycling companies, plastic processing companies, the food and cosmetics industry, and consulting companies.
The predecessor project PolyCycle has already provided initial findings: A significant proportion of the tested samples tested positive for genotoxic effects. These contaminations proved to be systematic, indicating that the substances originate from the recycling process. Particularly suspected are degradation products of printing inks that are formed during recycling. It is not certain that these effects are actually due to the printing inks. “It is only our most obvious suspicion. Other additives or adhesives or even post-consumer contamination could be the causes. However, we know that such genotoxic effects hardly ever occur with virgin plastics. In this respect, it must have something to do with the recycling itself,” explains Dr. Bernhard Rainer, project manager of SafeCycle from the Department of Packaging and Resource Management at the FH Campus Vienna, in response to an inquiry from FACHPACK360°.
If the suspicion is confirmed, the question arises as to how printing inks can be improved to make food packaging safer in the end. “If the printing inks are to be made safe for recycling, the degradation products that are produced during the recycling process must be examined for safety. Alternatively, compounds that can withstand the high temperatures could be chosen,” Rainer said. De-inking processes in the recycling process or specialized cleaning processes would also be an alternative, but it is questionable whether the required cleaning efficiencies can be achieved, the expert adds.
Test method for identifying carcinogenic substances
In the SafeCycle project, experts from the Sustainable and Future Oriented Packaging Solutions competence center are working with the OFI in Vienna and the IVV Fraunhofer in Freising to develop a test method for identifying potentially carcinogenic substances using liquid chromatography and high-resolution mass spectrometry in conjunction with in vitro bioassays. This will primarily identify sources of contamination in recycled plastics. “As the project progresses, these results will also be used to define measures to prevent future contamination and enable the use of recycled packaging materials in various application scenarios, such as food, cosmetics, and household products,” Rainer says. The project is geared toward investigating mono-materials, he says. Specifically, it is looking at the mechanical recycling of LDPE (low-density polyethylene), HDPE (high-density polyethylene), polypropylene, as well as polystyrene.
“If we can manage to identify material streams and recycling processes that are safe for food contact, we can make a major contribution to the circular economy,” says the scientist.
“With our SafeCycle research project, we now want to identify the causal step in the recycling process and make appropriate adjustments,” says Silvia Apprich, head of the Packaging and Resource Management Department at FH Campus Wien.
