According to a study conducted by Brazilian researchers from the Oswaldo Cruz Institute, wild sharks off the coast of Brazil have tested positive for cocaine. The study, published in the journal Science of The Total Environment, involved the examination of 13 Brazilian sharpnose sharks (Rhoprionodon lalandii) caught in fishermen’s nets near a beach in Rio de Janeiro.
Remarkably, all 13 sharks tested positive for cocaine, with the concentration being 100 times greater than that observed in other marine species. The drug, along with benzoylecgonine (the major metabolite of cocaine), was found in their muscle tissue and livers.
Researchers suspect that traces of cocaine were probably discharged into the coastal region, through raw sewage in rivers and urban canals. Another potential source of exposure is cocaine packs drifting in water and not discovered by drug smugglers or authorities, which pose a risk if sharks bite into them.
The study also found that cocaine levels were three times higher in the muscle than in the liver, and that female sharks had higher cocaine concentrations in muscle tissue compared with males. The amount of cocaine and benzoylecgonine found in the sharks “exceeded levels reported in the literature for fish and other aquatic organisms, by up to two orders of magnitude.”
This marks the first time cocaine has been detected in wild sharks worldwide, and the findings “point to the potential impacts of the presence of illicit drugs in environments.” Researchers also worry about cocaine re-entering the food chain, as the sharks are fished for their meat.
The impact of the drug trade on marine life is significant and multifaceted, primarily due to pollution from drug disposal. Illicit drugs, such as cocaine, and their byproducts often enter marine environments through improper disposal and wastewater discharge. These substances are resistant to conventional water treatment processes, allowing them to persist and accumulate in aquatic ecosystems.
This leads to bioaccumulation, where marine organisms, such as the Brazilian sharpnose sharks, absorb and retain high concentrations of these drugs in their tissues. Such contamination can cause severe physiological and behavioral changes in marine species, affecting their feeding, breeding, and social interactions. For instance, exposure to certain pharmaceuticals has been shown to disrupt endocrine systems and alter the natural behavior of fish.
Furthermore, this contamination can have cascading effects throughout the ecosystem, as drugs accumulate in the food chain, potentially impacting predators and other species reliant on contaminated organisms for food. Overall, the drug trade’s pollution poses a severe threat to marine biodiversity and ecosystem health, highlighting the need for better waste management and drug disposal practices to protect marine life.
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