(Rio de Janeiro) Brazilian scientists have said they have detected traces of cocaine in small sharks off the coast of Rio de Janeiro, a sign of the pollution to which they are exposed.
“We took 13 male and female specimens and we found cocaine in all of these animals,” in the muscles and in the liver, one of the people in charge of the study carried out for the Oswaldo Cruz Institute (IOC/Fiocruz) told AFP.
This is the first time this has happened anywhere in the world, according to the organization.
As top predators in the food chain, sharks are considered “sentinel” species for environmental damage.
PHOTO OSWALDO CRUZ FOUNDATION, PROVIDED BY REUTERS
A Brazilian sharpnose shark (Rhizoprionodon Lalandii) is analyzed in a laboratory in Rio de Janeiro, Brazil.
The specimens analyzed belong to the species of Brazilian needle shark (scientific name Rhizoprionodon lalandii) and were collected on the coast of the Recreio dos Bandeirantes neighborhood, in western Rio, between September 2021 and August 2023.
Benzoylecgonine, a substance produced by the metabolism of cocaine, was detected in their bodies.
“There were already several studies in the world showing the presence of cocaine in the aquatic matrix, in sea water, rivers and sewers. We wondered if in Brazil, the second largest cocaine market in the world, this drug was reaching the biota […]. And we have shown that [la flore et la faune] are actually exposed to this pollutant,” explained Enrico Mendes Saggioro.
The main hypothesis is that the pollution was caused by wastewater discharged into the sea, both by “users who eliminate the drug” by going to the toilet and “also by refining laboratories,” the scientist said. “International maritime traffic” is another hypothesis, “but this still needs to be studied,” he said.
As it is a non-migratory species, it is likely that the pollution occurred near the Carioca coast.
According to the researchers, the shark analyzed is a species consumed in Brazil and other parts of the world, but further studies are needed to determine whether people may be affected by its consumption.
Further analysis is also needed to determine the exact consequences of cocaine contamination in sharks, which could include impacts on growth or fertility, according to the scientists, who have already detected other contaminants in the animals. The research results were published in the journal Science of The Total Environment.