Scientists have identified traces of sertraline, a widely used antidepressant, in the brain tissue of hammerhead sharks captured along the Rio de Janeiro coast. Global sales of the medication are forecast to rise from roughly 1.94 billion dollars in 2025 to about 3.13 billion dollars by 2032. In Brazil, surveys show that 10.2 percent of the population has received a depression diagnosis and around 4 percent have taken antidepressants.
After human use, portions of the drug pass through the body and enter wastewater systems. Many treatment plants remove only limited amounts of pharmaceutical residues, allowing the compounds to reach the sea. In Rio de Janeiro state, roughly 47 percent of sewage undergoes effective treatment, with the remainder released through ocean outfalls.
The EcoShark Project, coordinated by researchers at the Federal University of Rio de Janeiro, has examined shark health since 2018. Analysis of specimens accidentally caught near Recreio, Barra da Tijuca, and Copacabana beaches revealed sertraline in the brains of critically endangered hammerhead species. As apex predators, sharks accumulate such substances through water, sediment, and prey.
Comparable detections of medications and other compounds have occurred in sharks near the Bahamas. The presence of sertraline in neural tissue suggests exposure and possible interaction with similar biological pathways in marine vertebrates, though further study is required to determine physiological impacts.
