The Plymouth scientists worked with collaborators from the University of Illinois at Urbana-Champaign to test a range of new and used consumer products, including children’s toys, office equipment, and containers for cosmetics.

They examined the levels of rare earth elements, and also levels of bromine and antimony. The latter elements are used as flame retardants in electrical equipment, rendering them a useful marker for the presence of recycled electronic plastic.

They found at least one rare earth element in 24 of the 31 products tested, including items where unregulated recycling is prohibited, such as single-use food packaging. Rare metals were most commonly observed in products containing bromide and antimony at levels insufficient to effect flame retardancy, but also appeared in plastics without these elements.

In general, rare earth elements are found in very low concentrations in the environment. Although the impact on human health of these elements is uncertain, research suggests that some have toxic properties and very high exposure can result in a wide of health problems, particularly when ingested or inhaled.

The researchers said that their findings – and evidence of rare earth elements in beached marine plastics – suggest that these elements may be ubiquitous and pervasive contaminants of consumer plastics, both contemporary and historical.

Although previous studies have found rare earth elements in a variety of environments, this study – the first to systematically examine the presence of the full suite of rare elements in a range of consumer plastics – demonstrates the broad contamination of the 'plastisphere'. This contamination does not appear to be associated with a single source or activity.

“Rare earth elements have a variety of critical applications in modern electronic equipment because of their magnetic, phosphorescent, and electrochemical properties,” said Professor Andrew Turner. “However, they are not deliberately added to plastic to serve any function. So, their presence is more likely the result of incidental contamination during the mechanical separation and processing of recoverable components.”

“The health impacts arising from chronic exposure to small quantities of these metals are unknown. But they have been found in greater levels in food and tap water and certain medicines, meaning plastics are unlikely to represent a significant vector of exposure to the general population. However, they could signify the presence of other more widely known and better-suited chemical additives and residues that are a cause for concern.”