Scientists have found traces of cocaine in the bodies of sand sharks off the coast of Brazil, a discovery that highlights the dangers of the illegal cocaine trade to marine life. The Brazilian sand sharks were caught by a fishing fleet off the coast of Rio de Janeiro state in southeastern Brazil between September 2021 and August 2023. In a study published in the journal Science of the Total Environment, 13 of the sharks – three males and 10 females – tested positive for cocaine. The drug was found in their muscle tissue and liver, as well as benzoylecgonine, the main metabolite of cocaine. The researchers do not know exactly how the sharks were exposed to the drug. However, they speculate that traces of cocaine likely entered coastal waters through untreated wastewater from rivers and city canals. Another possible source could be cocaine packages floating in the water undetected by smugglers or authorities. If they are bitten by sharks, it could be dangerous. The case is reminiscent of the “Cocaine Bear” story, when a 500-pound black bear in Georgia died of an overdose of cocaine believed to have been dropped from a plane carrying drugs. The bear’s remains were found in 1985 by drug investigators, and in 2023, the story became the basis for a horror film in which the bear descends into madness (in reality, authorities believe the bear likely died quickly of an overdose). Researchers said it was the first time cocaine had been detected in sharks, and their findings “indicate the potential impact of the presence of illegal drugs in the environment.” Scientists also fear that cocaine could reenter the food chain and sharks could be poached for meat. Previous research has shown that illegal drugs and legal prescriptions are accumulating in waters around the world, including in the state of Sao Paulo, where scientists say the drug is found. Cocaine contamination poses an ecological threat to marine life, including mussels and oysters. Researchers previously found that cocaine levels in the waters around Sao Paulo, home to Brazil’s most populous city, were similar to the amount of caffeine in coffee and tea, which they called “high concentrations.” Caffeine has also been detected in the state’s drinking water. In 2019, British scientists found that the number of freshwater shrimp exposed to cocaine and other pharmaceuticals in the country’s rivers had increased dramatically in recent decades, according to the United Nations. Brazilians are among the biggest consumers of the drug in South America, the study’s authors said. The Brazilian scientists chose the dwarf shark for their study because of its small size and the fact that it lives in an area subject to significant sewage pollution, making it an “environmental sentinel.” They found that cocaine levels in muscle were three times higher than in liver, and that female sharks had higher muscle cocaine concentrations than males. The amounts of cocaine and benzoylecgonine found in the sharks were “two orders of magnitude higher than levels reported in the literature for fish and other aquatic organisms.”
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