Opioids, muscle relaxant, a tranquilizer: what researchers found in dolphin blubbers

In a recent study published in the journal iScience, researchers from Texas A&M University-Corpus Christi (TAMU-CC) found traces of fentanyl and other pharmaceuticals in the blubber of bottlenose dolphins in the Gulf of Mexico. The team analyzed 89 samples, including 83 from live dolphins and six from deceased specimens, revealing the presence of various drugs such as fentanyl, carisoprodol (a muscle relaxant), and meprobamate (a tranquilizer). Of the dolphins tested, 30 showed the presence of at least one drug, with fentanyl detected in 18 samples.

"Pharmaceuticals have become emerging micropollutants and are a growing global concern as their presence has been reported in freshwater ecosystems, rivers, and oceans worldwide," said mammal zoologist Dara Orbach, according to BFMTV.

Dolphins could have absorbed the chemicals through their food or skin. Orbach explained, "It's likely they're getting these pharmaceuticals in their system from eating prey. Those prey being the same fish and shrimp that we’re also eating over here, considering that the Coastal Bend is such an important fishing community," she told ABC News.

The study began in 2020 after researchers found a dead dolphin in the Gulf near Robstown County, Texas. This area is close to the site of the largest seizure of liquid fentanyl in U.S. history in 2023. The researchers decided to tow the deceased dolphin back to campus for analysis. "We could tell the dolphin had just died because its tail was still moving," Orbach said, as reported by ABC News.

Doctoral student Makayla Guinn described the analytical process: "When I started this project, we did what we call an untargeted study of the blubber, where we put it in a very fancy instrument that’s able to resolve all the compounds inside. We were looking for what we actually found," she is cited by Earth.com.

Some of the samples analyzed were collected as early as 2013, indicating a long-standing issue of pharmaceutical contamination in marine environments. "That suggests this is a long-standing problem in the marine environment," Orbach stated, according to Bild.

Dolphins serve as effective bioindicators of ecosystem health due to their lipid-rich blubber, which can store contaminants. They are considered key in monitoring pollution levels because they accumulate pollutants through the food chain.

"These drugs and pharmaceuticals are entering our water and they have cascading effects in our marine life," Guinn said, according to Earth.com.

The sources of pharmaceutical contamination could be varied, including wastewater discharges, human sewage, or the dumping of drugs by trafficking ships.

"This is something that we really need to monitor with time, so that we need to make sure that we're not seeing increases in fentanyl concentrations," toxicologist Christiana Wittmaackshe is cited by ABC News.

"When more and more factors are added, the dolphins become so vulnerable that they can no longer respond," Orbach said, as reported by ABC News.

This article was written in collaboration with generative AI company Alchemiq