Sharks Test Positive for Cocaine Off the Coast of Brazil

The findings are concerning, to say the least.

Scientists found the presence of cocaine in over one dozen sharks tested off the coast of Brazil, in a findings published in a study earlier this month. The exact cause is still unknown, but is raising concerns about potential widespread ocean contamination. 

Marine biologists with the Oswaldo Cruz Foundation made the first-of-its-kind discovery, after 13 Brazilian sharpnose sharks in the coastal waters near Rio de Janeiro were found to have high traces of the drug in their muscles and liver tissue. The concentration of cocaine was said to have been as much as 100 times higher than traces of the drug previously recorded data found in aquatic life.

Experts have posited a few different theories for cocaine turning up in the bodies of the sharks, which are typically found in the tropical waters of the western Atlantic Ocean.

One possible explanation is that the cocaine is directly entering waterways via drainage from illegal drug labs, where the cocaine is manufactured and refined. Another possible contributing factor is that the drug is getting into the water through the excrement of drug users in untreated sewage, as cocaine has been detected in the rivers and sewage of many countries, including Brazil.

Another less likely explanation is that cocaine may be getting into the ocean due to packs either lost or dumped by drug traffickers on boats.

In either case, marine ecotoxicologist Sara Novais, with the Marine and Environmental Sciences Centre of the Polytechnic University of Leiria, told Science magazine that the findings are "very important and potentially worrying." Novais, who was not involved in the study, warns that more research is needed to determine whether the sharks are being harmed by the exposure, much less any predators that might eat them.

All of the female sharks in the study were found to be pregnant, though any impacts on the fetuses are likewise currently unknown.