Spanish researchers have confirmed for the first time that loggerhead sea turtles have a high concentration of plastic in their muscle tissue.
The effects of plastic waste in the oceans are widely reported, but this is the first time a science group has confirmed that pollution is affecting marine life on a chemical level.
Marine animals such as sea turtles frequently fall foul to fishing nets, waste in the oceans, and plastic that ends up in their system through consumption, often causing death.
The research, led by Doctor Ethel Ejarrat and scientists from the Spanish National Research Council (CSIC), was carried out with the involvement of the Institute of Environmental Assessment and Water Research and the University of Barcelona.
The study was recently published in the magazine Environmental Pollution thanks to the analysis of 44 loggerhead sea turtles (Caretta caretta) found dead on the Catalan coast and in the Balearic Islands between 2014 and 2017.
Doctor Ejarrat, 51, told Real Press in an exclusive interview: “There was a clear presence of those additives in the muscles of the analysed turtles.”
Regarding differences between the turtles found in Catalonia and the Balearic Islands, she said: “There were higher levels of plastic in the turtles from the Balearics and we believe turtles living along the Algerian coast have a higher presence of plastic waste than those along the Catalan coast.
“The research shows that plastic waste not only affects them on a physical level, when the turtles get stuck among the waste or it ends up in their digestive system, but also on a chemical level.”
Scientists analysed 19 chemical additives linked with plastics that are considered endocrine disruptors, neurotoxic, and even carcinogenic, especially plastics known as organophosphorus compounds (OPCs).
The research revealed the presence of plastics in all the turtles in concentrations between 6 and 100 nanograms per gram of muscle.
The levels are similar to those found in previous studies on OPCs such as polychlorinated biphenyl or Dichlorodiphenyltrichloroethane, commonly known as DDT, which, according to Ejarrat, “was banned years ago for being toxic”.
Luis Cardona, biology professor at the University of Barcelona, said in a press statement obtained by Real Press: “When eating sea waste voluntarily, they often mix it up with real food (such as jellyfish). Turtles are one of the groups of animals most exposed to contamination from plastic additives, although we do not fully understand the real impact of that yet.”
Scientists also analysed the turtles’ diet, mainly consisting of jellyfish, squids and sardines, alongside the sea waste they tend to consume such as plastic bags, bottle tops, and fragments of floating plastics, and the presence of OPCs were found in all samples.
Doctor Ejarrat told Real Press that the compounds could affect the turtles’ fertility as well as being linked to some cancer cases.
She added: “The toxic effect is not acute, but chronic toxicity. The fact they are exposed daily to these contaminants could cause problems for their whole life.”
If turtles are suffering these effects, Doctor Ejarrat said that it stands to reason that humans can also be exposed.
She said: “We are incorporating these compounds in our diet through fish as well as in the air while breathing so we are absorbing it and, depending on each one of us, our organism and metabolism can be affected sooner or later.”
The research also confirmed that, in comparison with other marine species like whales and dolphins, the levels of chemical additives linked with the plastics are higher in loggerhead sea turtles.
She said: “Turtles take in more plastics than whales or dolphins. For example, when whales filtrate water, they take in microplastics, but the levels of contaminants in the microplastics are lower than the macroplastic taken in by turtles.”
Loggerhead sea turtles are listed as ‘endangered’ on the Red List of the International Union for Conservation of Nature (IUCN).