Traces of different types of drugs have been found in the tissues of dolphins in the Gulf of Mexico, in the Atlantic Ocean, reports "Fox".

Researchers tested 89 dolphins in several areas of the Gulf and found that 30 of them had some level of drugs in their bodies, and 24 also tested positive for a painkiller that is hundreds of times stronger than morphine.

Data on the places where the concentration of cocaine was detected in the dolphins' bodies have not been published. The new paper also found the presence of fentanyl in these marine mammals. The sedative meprobamate and the muscle relaxant carisoprodol were also found in the adipose tissue of the tested animals. The researchers say they did not ingest the chemicals orally – by drinking water – but through the skin.

Marine mammal expert Dara Orbach said pharmaceuticals and drugs that end up as waste in the waters are serious micropollutants worldwide.

– Their presence has also been observed in freshwater ecosystems, rivers and oceans in many places around the world. When researching pollution, dolphins are often used as bioindicators of ecosystem health because they have lipid-rich blubber that can store the pollutants we're looking for, Orbach explained.

Hussain Abdullah, a chemistry professor at A&E University in Corpus Christi, Texas, added that these allegations raise a "red flag" for danger.

– The test results are what I would call a “red flag” – we are concerned and need to investigate further and see how big a problem this really is? Is this just the case with dolphins in the Gulf of Mexico or is it actually already common in waters around the world?, asks Prof. Abdullah.

In July of this year, scientists confirmed that sharks living in the waters off Brazil have cocaine in their tissues.