MIAMI.- Researchers in Brazil discovered that the sharpnose sharks that inhabit the country’s coastal waters are exposed to significant levels of cocaine. This finding, recently published in the scientific journal Science Directhighlights a worrying phenomenon that could have devastating consequences for these marine predators.
He studyled by Enrico Mendes Saggioro, an ecotoxicologist at the Oswaldo Cruz Institute in Rio de Janeiro, examined 13 sharpnose sharks caught on commercial whaling boats. Using advanced techniques, the team analyzed the sharks’ muscle and liver tissue, revealing cocaine concentrations up to 100 times higher than expected.
For the study, reported CNN reported that the species was chosen because of its small size and the fact that it lives in a small area of coastal waters, where it is exposed to significant discharges of pollutants throughout its life cycle, according to research.
Cocaine, sewage and the sea
“Cocaine pollutes the sea because of wastewater discharged by people who consume the drug, as well as illegal laboratories that produce it,” study co-author Enrico Mendes Saggioro told CNN.
“This discovery is alarming because it shows that sharks are absorbing cocaine in significant quantities,” Mendes told Science Direct. He also noted that females showed even higher levels of the drug compared to males, suggesting differences in how they metabolize the substance.
According to him studycocaine levels were approximately three times higher in muscle tissue than in the liver, while females had higher cocaine concentrations in muscle tissue compared to males.
Furthermore, the research highlights that cocaine use has increased massively worldwide in recent decades. The article added that around 22% of users live in South America, with Brazil being the second largest consumer market in the region. Increased consumption and poor wastewater treatment infrastructure have contributed to rising levels of cocaine in the sea, according to the researchers.
They explained that it is also difficult to establish the potential effects on human health, although “cocaine has already entered the food chain, as sharks are routinely consumed by humans in Brazil and many other countries.”
Vulnerable sharks
Los sharpnose sharksknown for their slender bodies, large eyes and long snout, are common along Brazilian coasts, especially in shallow waters near the beach. According to the Smithsonian Institution, they reach approximately 79 centimeters in length and are common at depths of up to 3 meters.
The research team suspects that the sharks’ proximity to the coast makes them particularly vulnerable to cocaine contamination, which could come from drains connected to clandestine laboratories where the drug is manufactured in Rio de Janeiro.
Although the exact effects of cocaine on sharks are still not entirely clear, Mendes warns that the presence of this psychoactive substance in the liver could interfere with the reproduction of females, potentially affecting the reproductive health of the species. In addition, there is concern about the possible impacts on the marine ecosystem in general, given that cocaine has also been shown to be harmful to other species such as crustaceans and molluscs, as well as to the development of fish.
Mendes Saggioro and study co-author Rachel Ann Hauser Davis, a biologist at the foundation, said previous research has shown that the drug affects other animals such as fish and mussels. Hauser Davis said it is “very likely” that crustaceans, fish and other animals that sharks prey on are also contaminated with cocaine.
Furthermore, due to a lack of research, it is not possible to prove any effect on shark behaviour, but “cocaine affects the brain and hyperactive and erratic behaviour has been observed in other animals,” they explained.
Mendes’ call for further research to better understand these effects and identify sources of pollution is crucial. It’s not just about protecting the environment, sharkswhich are an important source of food in Brazil, but also to assess the potential risks to human health resulting from the consumption of these contaminated animals.
This study underscores the urgent need for stricter policies and preventive actions to preserve the health of the oceans and the species that depend on them. Pollution by cocaine represents a growing challenge that requires a coordinated scientific and environmental response to mitigate its long-term effects.
Source: “Cocaine Shark”: First report on cocaine and benzoylecgonine detection in sharks, Science of The Total Environment, 2024, 174798, ISSN 0048-9697,