https://www.science.org/content/article/cocaine-sharks-found-waters-brazil
Now, scientists in Brazil report the first proof that the animals are indeed exposed to cocaine. Thirteen sharpnose sharks taken from coastal waters near Rio de Janeiro had traces of the drug in their muscles and livers, researchers report this week in Science of the Total Environment.

The findings are “very important and potentially worrying,” says Sara Novais, a marine ecotoxicologist at the Marine and Environmental Sciences Centre of the Polytechnic University of Leiria. Novais, who was not involved in the study, cautions that more research is needed to determine whether the sharks—or the humans who eat them—are harmed by the exposure.

Cocaine has been detected in sewage and rivers in many countries, including Brazil. Around Rio de Janeiro, the drug probably enters the sea directly in drainage from illegal labs where cocaine is refined. It also comes from drug users via untreated sewage. Cocaine packs lost or dumped by traffickers could also be a source.