Sharks in the Bahamas test for caffeine, pain relievers and even cocaine, research finds

Sharks in the Bahamas are consuming substances including caffeine, painkillers and cocaine, according to a new study by marine scientists who say it can affect the animals’ health and behavior.

The research team, made up of marine biologists and scientists from various international programs, analyzed blood samples from 85 sharks of five different species. The sharks are caught about four kilometers off the coast of a remote island and their blood levels are tested for 24 legal and illegal drugs.

Twenty-eight sharks had detectable levels of caffeine, two common anti-inflammatory painkillers, or, in one case, cocaine in their blood, according to the study. Some have tested positive for more than one substance.

Pharmaceuticals, illegal drugs and other substances are “increasingly identified as pollutants of emerging concern” in oceans and other waters, the researchers said. They noted that areas of “rapid urbanization and tourism-driven development” are at high risk. This is the first study to look at the effect of this pollution on sharks in the Bahamas, the researchers said.

“While the discovery of cocaine – an illegal substance – often attracts immediate attention, the prevalence of caffeine and drugs in the blood of many of the sharks analyzed is equally alarming,” said lead author Natascha Wosnick, a zoologist and associate professor at the Federal University of Parana in Brazil, in an email to CBS News. “These are legitimate, frequently used and often overlooked objects, yet their environmental footprint is clearly visible. This underscores the need to reexamine even our most common practices.”

The data showed that sharks with contaminated blood had changes in metabolic markers, including those linked to stress and metabolism. The researchers say it’s unclear whether the changes are harmful, but it’s possible they could lead to behavioral changes.

“What worries us the most is not the increase in violence against people, but rather the impact it may have on the health and stability of sharks,” said Wosnick. “Chronic exposure to these anthropogenic compounds, many of which have no natural analogue in marine systems, may lead to adverse effects that are still poorly understood.”

The researchers say the data highlights “the urgent need to address ocean pollution in habitats that are often perceived as clean.”

Tracy Fanara, a marine biologist who worked on a Discovery TV program called “Cocaine Sharks” that explored how sharks might be affected by the drug, he told CBS News in 2023 about experiments simulating cocaine exposure. He said it led to “unusual behavior” that required further research. During the show, he is heard commenting that a hammerhead shark seems to be after a lot of fake cocaine.

“My goal with this experiment was to shed light on the real chemical problem in our water and how it affects our aquatic life and ultimately affects us,” said Fanara in 2023. “But the purpose of the study was basically to see if this is a research question worth exploring further. And I would say, yes, it is.”

In a separate 2024 study, scientists reported that sharks in Brazilian waters tested positive for cocaine and benzoylecgonine, the main molecule of cocaine. Those researchers looked at the levels of substances in the shark’s liver and muscles. Each of the 13 sharks tested for the study tested positive for cocaine. CBS News reported at the time. The research team said more data will be needed to see how cocaine and other substances affect sharks and other wildlife.