While we know that huge amounts of plastic waste are generated each day, and that much of it is broken down into tiny fragments called microplastics, we don’t really know much about the risks they pose to animals and humans. With this in mind, scientists have developed a new method to detect trace amounts of plastic in tissues, and tried it out on a range of seafood to find plastic particles in all samples tested.
While we know that humans consume tiny amounts of plastics through things like bottled water or the seafood we eat, we really have no idea what effect this has on our wellbeing and what, if any, levels might be considered safe. The new technique is an early step toward addressing this, with an ability to identify and measure five different plastic types at the same time, with a high degree of sensitivity.
First, edible tissues are immersed in chemicals, which dissolves any plastics that might be present. The remaining solution is then analyzed through what’s known as pyrolysis-gas chromatography-mass spectrometry, which enables the scientists to see which plastic types are present, and in what quantities.
The research was carried out by scientists at the University of Exeter in the UK and the University of Queensland in Australia, who collected raw oysters, prawns, squid, crabs and sardines from a market. The analysis revealed plastics in all of the samples, at levels of 0.04 mg per gram of squid tissue, 0.07 mg in prawns, 0.1 mg in oysters, 0.3mg in crabs and 2.9 mg in sardines.
"Considering an average serving, a seafood eater could be exposed to approximately 0.7 mg of plastic when ingesting an average serving of oysters or squid, and up to 30 mg of plastic when eating sardines, respectively," says lead author Francisca Ribeiro. "For comparison, 30 mg is the average weight of a grain of rice. Our findings show that the amount of plastics present varies greatly among species, and differs between individuals of the same species. From the seafood species tested, sardines had the highest plastic content, which was a surprising result."
The plastic types found by the researchers come from everyday sources, such as packaging and synthetic textiles. These types of waste wash into the marine environment, where they are degraded and become tiny plastics that are nearly impossible to track. These types of advances can help scientists trace the path that they take through the environment, as well as better understand what impact they might be having on the animals and humans that consume it.
“We do not fully understand the risks to human health of ingesting plastic, but this new method will make it easier for us to find out,” says co-author Professor Tamara Galloway.
The research was published Environmental Science & Technology.
Source: University of Exeter
