Cocaine found in sharks caught along coast of Rio de Janeiro, Brazil, study shows

Cocaine was detected in sharks in Brazil, and no, this is not the plot of a movie .

Researchers at the Oswaldo Cruz Institute in Brazil found cocaine in 13 Brazilian Sharpnose sharks caught off the coast of Rio de Janeiro, according to the study published last week. Three of the sharks, also known as "rola-rola sharks” and “chicken sharks," were males and the other 10 were females, five of which were pregnant.

The study, conducted between September 2021 and August 2023, allowed researchers to "assess environmental health" and "focus on monitoring changes in the environment" to see how changes impact various forms of marine life, whether occurring naturally or at the hands of humans, the institute said.

“In Brazil, studies have already detected cocaine contamination in water and a few aquatic creatures, such as mussels. Our analysis is the first to find the substance in sharks,” pharmacist Enrico Mendes Saggioro, one of the researchers behind the study, said in a statement.

How did the sharks ingest cocaine?

The group found that all muscle and liver samples tested positive for cocaine, according to the institute.

"To our surprise, cocaine was found in greater concentration in the muscle, which is a tissue where it accumulates, which could indicate the abundance of the substance in the marine environment," Saggioro said. "Sharks could be becoming contaminated in several ways, either by living in the region or by feeding on other contaminated animals."

When comparing data from the study with others published on the contamination of other species, the average level of cocaine identified in sharks was higher than that detected in other animals, the institute said, citing experts.

“As the next steps, we intend to collect and analyze water samples and samples of other animals from this and other regions of the coast of Rio de Janeiro,” Rachel Ann Hauser-Davis, one of the study's authors, said in a statement.

Why did the group test sharks for cocaine?

Hauser-Davis said sharks play an important role in the marine ecosystem because as predators, they are "central figures in the food chain" and are considered "sentinel species" for locating environmental damage, including various forms of contamination.

The group of researchers chose Brazillian Sharpnose sharks due to their small size and their habitat, which is a small area of coastal waters where the species is exposed to contaminant discharges throughout its entire life, according to the study.

Based on the shark usually living close to the coast, researchers determined that the likely location of contamination was the coast of Rio de Janeiro.

“Specific studies are needed to determine the exact consequences of this contamination on the animals,” Hauser-Davis said. "It is believed that there may be an impact on the growth, maturation and, potentially, fertility of sharks, since the liver plays a role in the development of embryos."

Although the contamination can significantly affect sharks and marine life, Saggioro said "the risk to humans is minimal" because swimmers' contact with the water is minimal and people don't use seawater to eat or drink.

This article originally appeared on USA TODAY: Cocaine found in sharks caught along coast of Rio de Janeiro, Brazil, study shows