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It may seem like science fiction, but researchers have discovered real “cocaine sharks” off the coast of Brazil.
Thirteen Brazilian wild sharks (Rhizoprionodon lalandii) caught near Rio de Janeiro have tested positive for the drug, according to a study published last week in the journal Science of the Total Environment. The team is still reading the implications of this finding, but they don’t yet say it adds to the growing framework of evidence that human use of illegal drugs affects the environment.
Previous studies have detected cocaine in wastewater and rivers. Last year, English researchers discovered a chemical produced through the liver after ingesting cocaine in seawater. Studies have also found the drug in other sea creatures, such as shrimp, mussels and eels.
But the researchers were curious whether cocaine could have effects on sharp-nosed sharks that spend their entire lives in coastal waters near Brazil, which is the main exporter of the drug to Europe. In addition, in Brazil and elsewhere, people occasionally eat sharks, raising questions about possible contamination further up the food chain.
For example, the team purchased thirteen sharpnose sharks from small fishing boats between September 2021 and August 2023. All of the sharks were juveniles or small adults, about 20 inches long and weighing less than two pounds. Three were men and ten women; Five of the female sharks were pregnant.
They dissected the creatures in the lab and then analyzed their liver and muscle tissue. All tissue samples tested positive for cocaine and its metabolites, with concentrations up to a hundred times higher than those found in the past in other marine animals. When the team saw the results, they were “really stunned,” study co-author Rachel Ann Hauser-Davis, a biologist at the Oswaldo Cruz Foundation, affiliated with Brazil’s Ministry of Health, told Sarah Hurtes of the New York Times. Formation
“We were very excited, but this is an unprecedented report,” he added. “This is the first time this knowledge has been discovered for a more sensitive predator. “
Many questions remain unanswered. How did sharp-nosed sharks get exposed to cocaine to begin with?Researchers aren’t sure, but they have some theories. It is possible that they ate packages of cocaine abandoned by traffickers. The cocaine would also have likely made its way into coastal waters as runoff from illegal refining labs. It is very likely that untreated sewage entering the ecosystem may also have contained cocaine in the waste of drug users. From there, the sharks ingested it directly through their gills or acquired it by eating smaller, infected fish. .
“Regardless of the origin of the drug, which is not yet imaginable to determine, the effects show that cocaine is widely advertised and transported in Brazil,” said study co-author Enrico Mendes Saggioro, a biologist at the Oswaldo Cruz Institute. Tiago Rogero del Guardian. Cocaine has a low half-life in the environment, so if we find it in an animal like this, it means that many drugs are entering the biota.
It is also unclear if and how cocaine might have affected the sharks’ habit or fitness, or whether it affected the pregnant women’s fetuses. Previous studies have suggested that cocaine may be poisonous or cause fitness disorders in aquatic creatures. The researchers note Although the amount of cocaine found in the sharks was quite low, the women had higher levels of cocaine than the men.
The International Union for Conservation of Nature classifies Brazil’s sharp-nosed sharks as “vulnerable,” largely due to overfishing.
Another important issue is whether humans can be harmed simply by eating “cocaine sharks. “This could simply prompt long-term studies as well as tests on other species of sharks, estuary-dwelling rays and migratory fish, Mendes Saggioro told CNN’s Jack Guy.
In addition, the outside researchers note that the duration of the study pattern was small and that the team did not collect water patterns from the domain where the fish were caught. These limitations increase the need for more research.
Despite cocaine’s mysterious origins and its effects still difficult to comprehend in humans and animals, these findings serve as a wake-up call about “the growing danger of cocaine contamination,” says Anna Capaldo, an endocrinologist at the Federico II University of Naples. in Italy. who are not interested in research, to Erik Stokstad of Science.
And although the presence of cocaine may be shocking and striking, it is far from the only destructive man-made substance that contaminates the planet’s waters.
“People are interested in cocaine,” Tracy Fanara, an environmental engineer from Florida who worked on the 2023 documentary “Cocaine Sharks,” told the New York Times. “But we have antibiotics, antidepressants, pharmaceuticals, sunscreens, insecticides, fertilizers. All of them enter our ecosystem.
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