Sertraline It is probably the most prescribed antidepressants on the earth. Global sertraline sales are expected to proceed to grow. It will grow from US$ 1.94 billion in 2025 to about US$ 3.13 billion by 2032..
In Brazil, A national survey indicates that 10.2% of Brazilians are diagnosed with depression, and it’s estimated that 4% use antidepressants..
But what people do know is that after being metabolized by the body, a few of these pills take one other route: they’re excreted within the urine, enter the sewage system, and go straight into the ocean.
And in Rio de Janeiro, besides all the great thing about the ocean, there are also sharks.
A find that nobody expected.
gave The EcoShark Projectcoordinated by Mariana Alonso, a professor at Carlos Chagas Filho at the Institute of Biophysics UFRJhas been monitoring the health of sharks off the coast of Rio de Janeiro since 2018. Other scientists were also involved on this research, viz José Souto-Neto and Victor Alves, and is a crucial initiative on emerging pollutants. elasmobranchs.
The study, which has yet to be submitted for publication but has already been shared amongst UFRJ scientists, identified sertraline — the lively ingredient in Zoloft — and dozens of generic versions within the brain tissue of hammerhead sharks. And ), classified as a critically endangered species (IUCNIbama)
The hammerhead sharks tested were by chance caught in fishing nets on the beaches of Recreio, Barra da Tijuca, and Copacabana and sent for evaluation due to a partnership between UFRJ fishermen and researchers. As apex predators, sharks are highly liable to bioaccumulation and biomagnification of contaminants within the food chain. As the shark swims and feeds, it constantly takes in pollutants from the water and sediment, while also absorbing all of the pollutants from its prey, akin to other fish and cephalopods (squids and octopuses) that also swim and feed. And, increasingly, the contaminants in these food chains are residues from our medicines.
The path to medicine
How does a human antidepressant reach a shark’s brain? Way less surprising than that.
When an individual takes sertraline, the body metabolizes many of the drug within the liver. Sertraline will be either unchanged or metabolized, and each forms find yourself within the sewage system.
Conventional wastewater treatment plants were designed primarily to remove organic matter, nutrients, and microorganisms. And removal of pharmaceutical compounds is commonly incomplete. As a result, Traces of antidepressants and their metabolites are found in treated effluents and in the aquatic environment.
In the Brazilian state of Rio de Janeiro, only 47 percent of sewage generated is effectively treated, in line with recent Brazilian data. National Sanitation Information System.
A significant slice of the sewage is discharged into the ocean through the Ipanema and Barra da Tijuca submarines. With only preliminary treatment, these systems fail to remove pharmaceuticals, releasing molecules into the coastal environment, where they’re absorbed by fish and marine invertebrates directly from the water or through their weight loss program.
In sharks, various contaminants accumulate in specific tissues, particularly the liver. In the case of sertraline, its affinity for lipid-rich tissues and the nervous system may help explain its identification within the animal brain.
This is just not an isolated case.
Rio de Janeiro is just not alone on this map. In March 2026, one The study published in the journal It was revealed that 28 of 85 sharks sampled near Eleuthera Island within the Bahamas had detectable levels of cocaine, caffeine and painkillers of their blood.
Brazilian researchers tested the samples and located painkillers and cocaine within the shark. The finding has modified perceptions: If drugs are present in sharks on a sparsely populated Caribbean island, what can we expect from swimmers lower than 1 km (0.6 miles) off Rio’s beaches? The study also found physiological changes within the animals, suggesting that these substances may affect their biochemistry.
Why the shark brain is an issue
Sertraline, which acts on serotonin within the human brain, was present in shark brain tissue. This indicates exposure and bioaccumulation. Because this serotonin transporter could be very much like vertebrates, the drug could theoretically interact with animal proteins. But detection alone doesn’t yet allow us to conclude that the animals have undergone behavioral or physiological changes.
Science already shows that sertraline can affect other marine animals: within the laboratory, zebrafish exposed to 0.1 µg/L of sertraline – present in coastal waters – produce changes within the serotonergic system, in addition to hypokinesia and learning delays.
What’s not yet known—and that is the query EcoShark is attempting to answer—is what these compounds do to elasmobranchs. Sharks have a unique neurochemistry than bony fish, which has similarities to mammals. The answer, currently, is a matter mark weighing a whole bunch of kilos.
An issue that can not be ignored
Brazil has it. Highest death rate from shark incidents in the world. In 2021, the recorded mortality rate reached 30% – compared with 1% within the United States and 14% in Australia.
Personal archives, Provided by the writer (not reused).
No, we are usually not suggesting that antidepressants cause an attack in seas. But science has an obligation to ask one other query: If these drugs, in relevant concentrations, change the behavior of fish within the lab, what actually happens to sharks chronically exposed to them on the earth’s most polluted coastal areas?
What is at stake beyond the plain?
The discovery of sertraline within the brains of hammerhead sharks in Rio de Janeiro touches on three crises that Brazil still considers separate.
The first is the mental health crisis. In Brazil, between 2023 and 2025, the use of antidepressants among adults aged 29 to 58 years will increase by 12.4%.. This increase in itself is just not an issue. This reflects advances in diagnosis and access to treatment. But every bullet has a second destination that is just not being monitored.
The second is the sanitation crisis. Until nearly half of Rio de Janeiro’s sewage is treated — with none process able to removing pharmaceutical compounds — the ocean will proceed to function a dumping ground for our household medicine cabinets.
The third crisis is certainly one of conservation: the hammerhead shark, a critically endangered species, is crucial to ocean balance – its presence regulates and stabilizes the food chain. Changing the animal’s neurochemistry is an unintended and uncontrollable experience.
That must be modified.
The three tasks are immediate and never mutually exclusive. Brazil’s environmental monitoring protocol should include systematic tracking of pharmaceuticals in sharks, rays and cetaceans. The methodology already exists — namely the EcoShark and EcoDELFIS projects. What is missing? Continued funding and a public policy that values and recognizes pharmaceuticals as an emerging pollutant.
The country’s wastewater treatment plants should be modernized to remove pharmaceutical micropollutants.
Funding for marine ecology research must be increased. Brazil has nearly 8,000 kilometers (5,000 miles) of coastline, probably the most biodiverse regions on the planet, and now sharks have antidepressants of their brains.
Sertraline was created to alleviate human suffering. The incontrovertible fact that it has reached the nervous system of a predator just just a few kilometers off the coast of Copacabana is a transparent indication of the extent to which this species is leaving its mark.