Sharks off the coast of Brazil have tested positive for cocaine, according to scientists.
Marine biologists examined 13 Brazilian sharpnose sharks near Rio de Janeiro and discovered high levels of cocaine in their muscles and livers.
The detected concentrations were up to 100 times higher than those previously reported in other aquatic species. Conducted by the Oswaldo Cruz Foundation, this study is the first to identify cocaine presence in sharks.
Experts suggest that cocaine might be entering the waters through illegal drug manufacturing labs or the excrement of drug users.
Although less likely, lost or discarded cocaine packages by traffickers could also contribute.
Sara Novais, a marine eco-toxicologist at the Marine and Environmental Sciences Centre of the Polytechnic University of Leiria, told Science magazine that the findings are “very important and potentially worrying.”
All female sharks in the study were pregnant, but the effects of cocaine exposure on their fetuses remain unknown.
Further research is needed to determine if cocaine is altering the sharks’ behavior. Previous studies have indicated that drugs can have similar effects on animals as they do on humans.
Last year, seawater samples off the south coast of England also revealed chemical compounds, including benzoylecgonine, which is produced by the liver after cocaine use.