Drugs in the waters

Sharks off the coast of Rio de Janeiro are on “coke”

(Bild: Glomex/dpa)

In the Brazilian coastal metropolis of Rio de Janeiro, sharks have tested positive for cocaine. The data would indicate the large quantities of the drug that are consumed in the city and disposed of into the sea via sewage, say scientists.

Researchers from the Oswaldo Cruz Institute detected the drug in the livers and muscles of 13 sharpnose sharks, according to the study published in the journal "Science of The Total Environment". 

"In Brazil, studies have already shown the contamination of water and some aquatic organisms, such as mussels, by cocaine. Our analysis is the first to find the substance in sharks," says pharmacist Enrico Mendes Saggioro, one of the researchers responsible for the finding together with biologist Rachel Ann Hauser-Davis.

Sharks important for the ecosystem
According to the biologist, as predators, sharks play a central role in the food chain in the marine ecosystem - they can be used to detect environmental damage, including various forms of pollution.

13 sharpnose sharks were on "coke".(Bild: Glomex/dpa)

According to the latest World Drug Report, published by the United Nations Office on Drugs and Crime (UNODC) in 2024, Brazil is one of the largest consumers of cocaine in the world. According to the available studies, researchers assume that the drug enters the sea primarily through the disposal of cocaine waste in wastewater.

Impact being investigated
Specific studies are needed to determine the exact consequences of cocaine exposure for the animals. "It is suspected that it affects the growth, maturation and possibly the fertility of the sharks, as the liver is involved in the development of embryos," says biologist Hauser-Davis.