Plastic is not a source of nutrition for us, however, each week each of us ingests polymer particles the weight of a credit card, that is, 5 grams of microplastics, according to the World Wildlife Fund.
That finding comes from a study conducted last year for the environmental group by researchers at Newcastle University in Australia, who found that we each consume about 2,000 small pieces of plastic each week, or 21 grams per month and 250 grams per week. year.
Pollution from microplastics, most of which are invisible to the naked eye, has reached endemic proportions and tiny polymer particles from plastic waste have made their way into the food chain of the planet's oceans. According to a new study, for which scientists examined five popular types of shellfish - oysters, prawns, squid, crabs and sardines - that they had purchased from Australian food markets, each item contained microplastic particles to varying degrees.
New study on microplastics in shellfish
Specifically, researchers from the University of Exeter in the United Kingdom and the University of Queensland in Australia analyzed raw shellfish (five wild blue crabs, 10 farmed tiger prawns, 10 farmed oysters, 10 wild squid and 10 wild sardines) with a new development. Method that helped them identify and measure five different types of plastic at the same time.
They found plastic levels of 0.04 milligrams per gram of tissue in squid, 0.07 mg in prawns, 0.1 mg in oysters, 0.3 mg in crabs, and 2.9 mg in sardines.
“Considering an average portion, a seafood consumer could be exposed to approximately 0.7 milligrams of plastic when eating an average portion of oysters or squid, and up to 30 mg of plastic when eating sardines, respectively,” observes Francisca Ribeiro, lead author of the study investigating dietary exposure to plastics at the University of Queensland.
"For comparison, 30 mg is the average weight of a grain of rice," he explains. “Our findings show that the amount of plastics present varies greatly between species and differs between individuals of the same species. Of the shellfish species tested, sardines had the highest plastic content, which was a surprising result. "
The plastic particles that end up in the fabric of the marine creatures that we consume come largely from plastic packaging and synthetic textiles: polystyrene, polyethylene, polyvinyl chloride, polypropylene and polymethyl methacrylate. In other words, as plastic waste disintegrates in the oceans, it continues to pollute by entering marine organisms and lodging in their tissues.
That happens because large numbers of creatures, large and small, from plankton to whales, unknowingly ingest microplastics with potentially dire consequences for their health and that of their ecosystem.
It's not just shellfish that threaten us either. Previous studies have found that microplastics have contaminated even bottled water and table salt. A group of scientists who tested 17 types of commercially available salt in eight countries, for example, found heavy plastic contamination in the salts that people use in their kitchens.
"Of the 72 particles extracted, 41.6% were plastic polymers, 23.6% were pigments, 5.50% were amorphous carbon and 29.1% remained unidentified," they write in a study. “The particle size (mean ± SD) was 515 ± 171 µm. The most common plastic polymers were polypropylene (40.0%) and polyethylene (33.3%). The fragments were the main form of MP (63.8%) followed by filaments (25.6%) and films (10.6%) ".