DNA-Reactive Mutagens: How Safe Are Recycled Plastics?

The goals of the European circular economy require the use of recycled polymers –  even in sensitive areas such as food packaging. This is precisely why plastics for food packaging are increasingly becoming the focus of scientific research. The Ofi, FH Campus Wien and Fraunhofer were in charge of the study on the “Safety assessment of recycled plastics from post-consumer waste using a combination of a miniaturized Ames test and chromatographic analysis”.

The use of recyclates in food packaging has so far only been possible to a limited extent. Strict regulations must be adhered to – and for good reason: recycled plastics can contain impurities that originate from previous use and can be potentially harmful to health. Protecting the health and safety of consumers is a top priority. This is why EU regulations restrict the use of recyclates - to ensure that no hazardous substances are transferred to food. This is technologically challenging: many packaging consists of multi-layer composites, which provide optimum protection but are difficult to recycle. There is also the risk of undesirable odors or flavors from recycled material being transferred to food.

As recyclates can contain unknown substances, the European Food Safety Authority evaluates recycling processes using the worst-case scenario: any contamination is considered a DNA-reactive mutagen or carcinogen with extremely low safety limits. In the study mentioned above, 119 samples of recycled plastic materials were tested using a miniaturized Ames test to provide scientific evidence of the presence of such substances.

Study Result: Mutagenic Effects in Recycled Plastics

The results of the study, presented in fall 2023, caused quite a stir: No DNA-reactive mutagens were found in recycled polyethylene terephthalate (PET), which is already approved for food contact. This is positive and expected news, as there are functioning recycling systems in the bottle sector and PET is a “food-safe plastic”. These do not affect the packaged food, as no substances that could be released into the food are released from the polymers. However, other recycled plastics (polyethylene, polypropylene, polystyrene), which are currently not approved for food contact, showed mutagenic effects in 51 samples.

The scientists concluded from the Ames test data and the comparison of input and output materials that the DNA-reactive impurities do not arise by chance through misuse by consumers, but systematically during the recycling process. Elisabeth Pinter will be reporting on the future of polyethylene, polypropylene and polystyrene in sensitive applications at FACHPACK. The topic is of concern to the entire packaging industry – and time is already running out until 2030.