Caribbean Sharks Tested Positive for Cocaine, Caffeine, and Painkillers

Human pharmaceutical pollution has reached the sharks of the Caribbean. A study published in Environmental Pollution in early 2026 found cocaine, caffeine, and common medications in the blood of sharks near Eleuthera Island in the Bahamas, raising new concerns about the invisible chemical footprint that coastal development and tourism leave in even the most remote ocean environments.

The Numbers Behind the Headlines

Researchers led by biologist Natascha Wosnick of the Federal University of Paraná in Brazil, working with scientists from the Cape Eleuthera Institute and international partners, drew blood samples from 85 sharks near Eleuthera Island in the Bahamas. Each sample was screened for nearly two dozen legal and illegal substances across five species: Caribbean reef sharks, Atlantic nurse sharks, lemon sharks, blacktip sharks, and tiger sharks.

Four contaminants turned up in 28 of the 85 sharks, roughly one-third of the total: caffeine, cocaine, acetaminophen (the active ingredient in Tylenol), and diclofenac, a prescription anti-inflammatory. Caffeine was by far the most common, appearing across all three of the affected species. Cocaine was detected in just two sharks, one Caribbean reef shark and one lemon shark.

The study marks the first time caffeine and acetaminophen have ever been detected in any shark species anywhere in the world, and the first confirmed detection of diclofenac and cocaine in Bahamian sharks.