Contamination lead

Materials World magazine
,
1 Jul 2018

Research has shown that black plastic components made from recycled electrical equipment introduce lead into food-contact items. Ines Nastali reports.

According to research by the University of Plymouth, UK, chemicals such as bromine, antimony, and lead have been mixed into black plastic material produced from recycled content.

‘A combination of the growing demand for black plastic and the inefficient sorting of end-of-life electrical equipment is causing contaminated material to be introduced into the recyclate,’ it is stated in a university press release. 

The researchers used XRF spectrometry to assess the levels of a range of elements in more than 600 black plastic products such as food-contact items, storage, clothing, toys, jewellery, office items and new and old electronic and electrical equipment. ‘The team found that cocktail stirrers, coathangers, plastic jewellery, garden hosing, Christmas decorations, and tool handles were contaminated with bromium, antimony, cadmium, chromium, mercury, and lead.’

Lack of sorting

Brominated compounds are used in electrical plastic casings to make them flame retardant. Lead in electrical plastic is found to be a contaminant. Study lead author Dr Andrew Turner, a Reader in Environmental Science at the University of Plymouth, blames a lack of efficient sorting and separation equipment for black plastic recycling waste and harmful additives needed to produce electrical equipment and food packaging for the contamination. Black pigments have a very low sensitivity to near infrared radiation, which is used in recycling facilities to sort waste. 

Turner hasn’t received specific feedback from industry or recyclers yet, but he will continue his research. He told Materials World, ‘The next step of the research would be to evaluate the migration of the contaminants – i.e. how much actually comes out under simulated gastric or food-contact conditions.‘

Enamelled danger

Previous research by Turner has shown that the surface of enamelled drinking glasses and toys also contain lead and cadmium, 1,000 times above the legal limit, which could sometimes lead to ingestion when paint comes away from the product. 70% of the analysed glassware was contaminated. ‘Given that safer alternatives are available to the industry, the overall results of this study are both surprising and concerning,’ Turner said. He calls for change. ‘I believe consumers should be made aware of this, while retailers and the glass industry have the responsibility to eliminate toxic metals from decorated products.’

Back in the Balkans

Traces of metal pollution go back far longer than our modern times. Researchers from Northumbria University, UK, have found that ‘metal-related pollution began in the Balkans more than 500 years before it appeared in western Europe, and persisted throughout the Dark Ages and Medieval Period, meaning the region played a far bigger role in mineral exploitation than previously believed,’ they stated in a press release. They found lead-originating pollution dating back to 3600 BC.

From geochemical surveys of the sediment of the Creveni Potok, Serbia, peat bog and historical mining site, the scientists were able to determine environmental impacts, for example caused by metal-contaminated wastewater or chemical particles that have settled from the atmosphere to the ground.

‘What is most interesting is that after the Roman Empire fell in the third and fourth centuries AD, lead pollution continued and even increased, indicating that the strong mining and smelting culture developed by the Romans was carried on by the local population,’ lead author Jack Longman said. ‘This goes against the long-held view of barbaric hordes with little technological know-how ousting the Romans leading to the Dark Ages – as we term the 1,000 years following the Roman period.’

Read the full study, Black plastics: Linear and circular economies, hazardous additives and marine pollution, published in Environment International here: bit.ly/2y4IyVu

Read High levels of migratable lead and cadmium on decorated drinking glassware published in Science Direct here: bit.ly/2HKI1r8

The paper Exceptionally high levels of lead pollution in the Balkans from the Early Bronze Age to the Industrial Revolution is available via the journal PNAS:
bit.ly/2t1B7IJ