Sharks in waters off the coast of Brazil have tested positive for cocaine, scientists say.
Researchers have long suggested that sea life could be impacted by drugs dumped into the water by smugglers, with tonnes of cocaine found around Florida, South and Central America.
A study from the Oswaldo Cruz Foundation in Brazil has now found evidence sharks are in fact being affected by drugs polluting the ocean.
The scientists dissected 13 wild Brazilian sharpnose sharks that were bought from small fishing vessels, as the species spend their entire lives in coastal waters and were therefore most likely to be affected by pollution.
Muscle and liver tissue were then tested using a standard technique called liquid chromatography with tandem mass spectrometry – where molecules are separated in a liquid – to look for cocaine and benzoylecgonine, the main metabolite in the drug.
A juvenile Atlantic sharpnose shark. Pic: Teacher at Sea, NOAA Fisheries
All 13 sharks were positive for the drug, with a concentration as much as 100 times higher than previously reported for other aquatic creatures, the scientists found.
It marks the first study to find the presence of cocaine in free-range sharks, and found the substance was more prevalent in muscle tissue than in the shark’s livers.
However, the study said the field of research was “very limited” and the impact of cocaine or benzoylecgonine on aquatic life is not fully known.
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The research was published in the outlet Science of the Total Environment.
In June last year, the US Coast Guard seized more than 14,100 pounds (6,400 kg) of cocaine in the Caribbean Sea and Atlantic Ocean, with an estimated value of $186m (£142m).