Pilar Laguna Murcia


Updated Saturday, February 24, 2024-15:23

How far can the residues of the drugs we consume reach?

The preliminary results of a study by the University of Murcia show the

presence of antibiotics and anti-inflammatories

beyond the waters, in the organism of cetaceans

that stranded on the Mediterranean coast


Ibuprofen is


most detected active ingredient, followed by



Marfarisk is a pioneering study on these species that is being carried out at the Faculty of Veterinary Medicine of the University of Murcia (UMU), where they had previously analyzed the

presence of other contaminants (metals, pesticides, oil and plastics)

in a hundred marine mammals, mostly dolphins of various species.

These toxic substances are already standardized in the risk maps of the European Union, while the

presence in community waters of antibiotics

, especially


, and non-steroidal

anti-inflammatory drugs

(NSAIDs) such as ibuprofen and diclofenac, which are the most used.

Antidepressants also play their part.

Cetaceans are marine animals that are not administered antibiotics, as can happen with land mammals, especially poultry, which are integrated into the food chain.

These cetaceans are not edible in our environment

, they circulate freely in the sea and the drugs reach their bodies mainly through environmental waste.

How do drugs reach dolphins and pilot whales?

There are different routes, but the main one is wastewater


although livestock and aquaculture also play a role as sources of diffuse pollution.

"There are currently new technologies in wastewater treatment plants, but they involve a high cost in water treatment and most drugs can be persistent due to their continuous diffusion in the aquatic environment," comments the main researcher, Emma. Martínez, professor of Toxicology in the Department of Social and Health Sciences at the UMU.

And it should also be taken into account that

in the Mediterranean basin there are countries that are world leaders in the production and export of pharmaceutical products

, as well as large consumers of medicines (including Spain).

The findings would confirm in some way

how difficult it is to "put doors to the sea"


Although the EU does not allow marine crops to be treated with antibiotics, other countries such as China continue to do so.

The oceans are the drains of the planet

"The oceans constitute a global compartment that is especially susceptible to the accumulation of chemical pollution since they act as the planet's drain, so that the majority of pollutants released into the environment or their metabolites, if they have the necessary persistence, will eventually end up in the marine waters, thus becoming the reservoir of these substances," argues Emma Martínez.

Some authors had detected the

presence of these drugs in coastal marine waters

and in waste and river waters that flow into the Mediterranean Sea, in concentrations that ranged from non-detection to 3000 ng-L-1, but they themselves point out the lack of data for seawater and also to correctly assess the risk associated with pharmaceuticals.

And to the best of UMU researchers' knowledge, Marfarisk would be the first study to delve into the bodies of superpredators to detect medications.

According to this toxicologist,

cetaceans around the planet are exposed to different concentrations of different mixtures of pollutants

, which, together with other anthropogenic stressors (e.g., depletion of their prey, noise pollution) or natural stressors (e.g., epidemics, parasites), can have fatal consequences on the health of their individuals and populations.

Pilot whales.GABRIEL LÓPEZ

"Fundamentally, exposure to these contaminants will be through diet, since they are lung animals lacking gills or other types of respiratory epithelia intended for gas exchange from the aqueous environment, as occurs with fish or marine invertebrates."

This would be one of the several characteristics that give value to the toxicological information obtained from contaminants in different species of cetaceans.

And, in addition to helping the well-being of these animals, it can be used to develop measures and public policies to mitigate marine pollution and protect the food security of human populations, whose food depends on marine resources.

"From a One Health perspective, marine mammals act as the best indicators of change in the marine environment and are sentinels for public health and the health of our oceans. Since they are long-lived animals, we share neurodegenerative diseases with them and they are more similar to us than many non-marine species," says the toxicologist.

What are the environmental risk indicators?


is the acronym of the project '

Marine mammals as risk indicators for emerging environmental pollutants on the coasts of the Region of Murcia

', framed in the national initiative of Complementary Plans promoted by the Ministry of Science and Innovation and the Autonomous Communities.

In this UMU study,

some 200 samples of 60 cetaceans

have been analyzed , in collaboration with the Stranding Network of the Region of Murcia.

The majority are striped dolphins, but there are also individuals of bottlenose dolphins, common dolphins, pilot whales and gray pilot whales.

The causes of death of the majority of individuals are unknown, although in several cases trauma is evident.

The project, still ongoing until the end of the year, has focused on macrolide antibiotics, especially ciprofloxacin, azithromycin clarithromycin and erythromycin, which are compounds included on the watch list under the EU Water Framework Directive;

and, on the other hand,

in ibuprofen and diclofenac

, the NSAIDs most consumed in Spain and the most detected in our rivers.

These researchers work with internal tissues, such as those of the liver, muscle and kidney

Emma Martínez believes that if, using a series of biomarkers, they have detected the medications they were looking for, it is because they are reaching the body of these marine mammals in notable quantities, since without being such persistent contaminants as pesticides, they appear in various organs of the cetaceans.

The most detected drug and the one with the highest concentrations in all the

tissues studied (liver, muscle and kidney)



, which appears in more than half of the individuals studied.


is also detected, but in a smaller proportion and with lower concentrations


On the other hand, the initial results of macrolides in kidney and lung suggest that


is the most detected antibiotic and with higher concentrations, although always below the amounts of ibuprofen.





have not been detected in these

two biological matrices



is only quantifiable in just one kidney sample.

Martínez specifies that depending on the type of drug, detections are greater in the liver, muscle or kidney because it depends on the toxicokinetics of each compound, but the mechanisms used by these species to metabolize and eliminate them are unknown.

However, the new data offer some clues: "The fact of

detecting these drugs in top predator species

makes us think that there is a constant flow of elimination into the natural environment. And despite the existing differences, we believe that these results could be used as warnings for prevention on human health in the face of the direct and indirect effects of these environmental pollutants".

Significance of the health of cetaceans

Emma Martínez claims the role of cetaceans as an essential component of marine biodiversity.


Cetaceans are essential agents in maintaining the health

and integrity of marine ecosystems due to their position at the top of food webs as top predators and large consumers of biomass, but also due to their participation in oceanic biogeochemical cycles through capture of carbon the redistribution of nutrients and minerals, especially in the case of large whales.

And they add their indirect, incalculable economic value by being essential animals for the maintenance of marine biodiversity, including fishing resources and the good environmental state of the oceans.

From now on, the Oceanosphera group will integrate these emerging toxins (not because they are new, but because they are "lawless" waste from an environmental point of view) to the increasingly long list of pollutants in rivers and oceans.

"It is very important that we can incorporate this until now unknown information, because in the marine environment we had only worked on fish, not on super predators, and we do not know how far the residues of the medicines we consume reach in nature," concludes the researcher.