Sharks in the Bahamas have been found to carry traces of cocaine, caffeine, and common painkillers, according to a recent study examining marine pollution in the area.
The research, led by biologist Natascha Wosnick from the Federal University of Paraná, was published on February 20, 2026, in the journal Environmental Pollution. Scientists analyzed blood samples from 85 sharks near Eleuthera Island and discovered that nearly one-third contained residues of human-related drugs.
These results add to growing concerns that ocean ecosystems are increasingly affected by contaminants linked to human activity, including wastewater discharge and drug trafficking.
Researchers identified substances such as caffeine, acetaminophen, diclofenac, and even cocaine in the sharks. The affected species included Caribbean reef sharks, nurse sharks, and lemon sharks. Caffeine was the most frequently detected compound and was recorded in sharks for the first time globally, while acetaminophen was also identified in sharks for the first time. Cocaine and diclofenac had not previously been documented in sharks in the Bahamas.
Scientists believe these substances enter the ocean through sewage systems, wastewater runoff, and human activity in high-tourism areas. Cocaine may also reach marine environments through lost or discarded drug shipments.
Some sharks showed metabolic changes linked to stress, including shifts in triglycerides, urea, and lactate levels. While behavioral effects have not been confirmed, studies on other fish suggest stimulants like caffeine could influence energy levels and risk behavior.
Earlier research by the same team in 2024 found even higher levels of cocaine in sharks off Rio de Janeiro, where all tested sharks were positive. That raised concerns about long-term exposure and possible effects on marine life and seafood safety.
Researchers say further studies are needed, but the findings highlight how deeply human pollution is reaching even top predators in the ocean.