Sharks off Brazil’s coast have tested positive for cocaine, a first-time detection in free-ranging sharks. Scientists from the Oswaldo Cruz Foundation found cocaine in liver and muscle tissue of all 13 Brazilian sharpnose sharks. The species was chosen due to its small size and exposure to contaminants.
Cocaine levels were three times higher in muscle tissue than liver tissue, with female sharks having higher concentrations. The drug pollutes the sea through sewage discharges from humans who use cocaine and illegal laboratories that produce it.
Increased consumption of cocaine worldwide has led to higher levels in the sea due to poor sewage treatment infrastructure. While previous research suggested dumped cocaine was responsible for contamination, this study found no evidence of trafficking dumping at sea.
The impact on shark health is unknown, but previous research has shown cocaine harms other animals like fish and mussels. Exposure may have negative physiological effects, and it’s likely that crustaceans, fish, and other prey are also contaminated.
Cocaine has entered the food chain as sharks are eaten by humans in Brazil and globally. The study plans to analyze more species of sharks and rays, as well as migratory fish like mullet.
Source: https://edition.cnn.com/2024/07/23/science/cocaine-sharks-brazil-scli-intl-scn/index.html