Sharks in Vacation Hotspot Test Positive for Odd Substances

Marine biologists in the Bahamas tested shark blood to study the animals' health and made a shocking discovery.

One shark had detectable levels of cocaine. Twenty eight had detectable levels of caffeine, two over-to-counter pain relievers. They were tested for 24 legal and illegal drugs, including:

• Acetaminophen (pain reliever)
• Benzoylecgonine (molecule in cocaine)
• Caffeine
• Carbamazepine (seizure medication and also used for bipolar syndrom
• Ciprofloxacin (antibiotic)
• Citalopram (antidepressant)
• Clindamycin (treats infections)
• Cocaine
• Diclofenac (pain reliever)
• Fipronil (insecticide for fleas)
• Fluoxetine (antidepressant)
• Nimesulide (pain reliever)
• Piroxicam (arthritis medication)
• Sertraline (antidepressant)
• Sulfamethoxazole (antibiotic)
• Triclosan (found in toothpaste and cosmetics)
• Trimethoprim (antibiotic)
• Tramadol (for severe pain)

Five Species of Sharks

The research team analyzed blood samples from 85 sharks of five different species including:

• Lemon sharks
• Atlantic Nurse sharks
• Blacktip sharks
• Caribbean Reef sharks
• Tiger sharks

The findings were published in the journal Environmental Pollution.

“While the detection of cocaine — an illicit substance — tends to draw immediate attention, the widespread presence of caffeine and pharmaceuticals in the blood of many analyzed sharks is equally alarming,” said lead author Natascha Wosnick, a zoologist and associate professor at Brazil's Federal University of Parana, in an email to CBS News. “These are legal substances, routinely consumed and often overlooked, yet their environmental footprint is clearly detectable. This underscores the need to critically reassess even our most normalized habits.”

In a previous study, sharks off the waters in Brazil tested positive for cocaine and benzoylecgonine, the molecule that makes cocaine.

What Does This Mean For Beachgoers?

The scientists do not think this should affect swimmers; they are more concerned with the overall health of the shark population.