13 Sharks Test Positive for Cocaine Near Brazil

Scientists have detected cocaine in multiple sharks off the coasts of Brazil, according to a new study.

In the study, which was published in the journal Science of the Total Environment, researchers set out to analyze the levels of cocaine as well as benzoylecgonine, a metabolite of cocaine, in Brazilian sharpnose sharks (Rhizoprionodon lalandii).

The scientists biopsied 13 of the sharpnose sharks, which had been caught in fishing nets, The Guardian reported. They found cocaine in all 13 sharks, and 12 of the 13 sharks tested positive for benzoylecgonine.

The study noted that cocaine can make its way to aquatic environments via poor sewage treatment and waste management, drug refining operations and unrecovered drifting cocaine packs.

^{A graphical abstract of the study. Science of The Total Environment}

“Regardless of where the drug came from — which is still not possible to determine — the results show that cocaine is being widely traded and moved in Brazil,” Enrico Mendes Saggioro, coordinator of the study and an ecotoxicologist at the Oswaldo Cruz Institute, told The Guardian. “Cocaine has a low half-life in the environment… so, for us to find it in an animal like this, it means a lot of drugs are entering the biota. In other studies, I had already found cocaine in rivers flowing into the sea off Rio, but it was a surprise to find it in sharks — and at such a high level.”

Drugs can bioaccumulate in aquatic life, leading to issues such as behavioral changes, reproductive impacts, and even physical alterations that affect the creatures. 

In April 2024, a separate study revealed that cocaine was bioaccumulating in brown mussels in the Bay of Santos, a popular destination in Brazil, Newsweek reported. Researchers have warned that the presence of cocaine and other drugs in marine life can also pose threats to the humans that consume seafood from contaminated areas.

“It is worth remembering that sharks are often sold irregularly under the popular name of dogfish. We have already found several toxic metals in dogfish and rays, which are also sold and consumed,” explained Rachel Ann Hauser-Davis, a co-author of the study and biologist at the Oswaldo Cruz Institute. “Now, we detect cocaine in sharks. Pollution and contamination of the environment directly affect animals and nature, but they also impact, in one way or another, human life. One person’s health is linked to the other’s health.”

Illicit and pharmaceutical drugs are continuously threatening aquatic life, according to recent findings. In June, researchers published a paper expressing the need for greener medications to prevent environmental damage. In another study published in June, scientists found high levels of pharmaceutical and recreational drugs in waters around southern England that could have detrimental impacts on aquatic life. Yet another study published in March of this year revealed the presence of prescription drugs in waterways around Florida.

The researchers who discovered cocaine present in Brazilian sharpnose sharks have plans to continue their research, collecting and analyzing samples from other species as well as waters around Brazil.