Caffeine, Cocaine, and Painkillers Found in Sharks in the Bahamas — A Sign of Human Pollution Reaching Marine Predators

In waters often described as pristine, sharks are carrying traces of human drugs.

Researchers studying coastal species around Eleuthera Island in the Bahamas have detected cocaine, caffeine, and common painkillers in shark blood, showing how human-made chemicals are moving through marine ecosystems.

In a new study published in Environmental Pollution, researchers analyzed blood samples from 85 sharks and found several contaminants of emerging concern, including caffeine, acetaminophen, diclofenac, and cocaine. The findings mark the first time caffeine and acetaminophen have been detected in any shark species worldwide, and the first report of diclofenac and cocaine in sharks from the Bahamas.

More notably, sharks with these compounds in their systems also showed changes in physiological markers, highlighting how the exposure may be doing more than just passing through.

Drug Exposure in Sharks Alters Biology

The team didn’t just test for the presence of these compounds. They also measured markers tied to metabolism, stress, and organ function, including triglycerides (a type of fat in the blood), urea (a waste product linked to kidney function), and lactate (often associated with stress and low oxygen levels).

In Caribbean reef sharks, individuals with these substances in their systems had lower urea levels and higher lactate levels than those without detectable compounds, pointing to shifts in energy use and stress.

The patterns varied by species, but the overall trend was consistent. Exposure to these compounds was linked to changes inside the body. The study doesn’t show long-term health effects yet, but it offers early evidence that these substances may be affecting shark biology.

Read More: Some Sharks Bite Humans as a Form of Self-Defense

Multiple Drugs Detected in Shark Blood

To understand what sharks in this region are exposed to, researchers collected blood samples across five species, including Caribbean reef sharks, lemon sharks, Atlantic nurse sharks, blacktip sharks, and tiger sharks.

They screened the samples for a range of compounds, from antibiotics to antidepressants, but only a handful kept showing up, including caffeine, acetaminophen (a common pain reliever), diclofenac (an anti-inflammatory drug), and cocaine.

In total, 28 sharks had at least one of these substances in their systems. The detections were limited to three species, all of which spend time in nearshore environments where human influence tends to be strongest.

Caffeine was the most commonly found compound, appearing across multiple individuals and species. Cocaine appeared in only a small number of sharks. While it has been detected in sharks before, its presence here adds to growing evidence that these drugs are reaching marine predators.

Why It’s Happening in a Place That Seems Untouched

The Bahamas is generally considered a relatively undisturbed marine environment, but coastal development and tourism can still bring a steady stream of contaminants into surrounding waters.

Many of these compounds enter the ocean through wastewater, runoff, and urban discharge. Once there, they can linger in the water and be taken up by marine life, especially species that spend time in shallow habitats.

Sharks are particularly important to study because they sit near the top of the food chain and tend to live long lives. That combination makes them more likely to accumulate contaminants over time and more vulnerable to long-term effects that are not yet fully understood.

This study is one of the first to examine these exposures in sharks from the Bahamas. It also highlights a broader gap in research, as most work on pharmaceutical pollution has focused on freshwater species rather than marine predators.

Read More: Sharks Began Roaming the Oceans 400 Million Years Ago as Deep-Sea Bottom-Dwellers

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