The Baltic Sea faces a severe ecological crisis as researchers from Sweden, Finland, Lithuania, and Latvia warn that pharmaceutical pollution is adding intense pressure to an already vulnerable semi-enclosed marine environment. Surrounded by nine countries in northeastern Europe, the Baltic Sea carries decades of legacy pollution, including chemical munitions dumped after the Second World War, microplastics, industrial chemicals, and agricultural runoff. Now, scientists are turning their attention to the life cycle of human and veterinary medicines entering the water.
Beyond Wastewater Treatment at the Shoreline
Researchers argue that the Baltic’s pharmaceutical contamination cannot be solved entirely at the shoreline through conventional infrastructure. Marmar Nekoro, a researcher at the faculty of pharmacy at Uppsala University in Sweden, explained to Euronews that addressing wastewater treatment alone is insufficient. “It’s not only about wastewater treatment,” Nekoro noted. “We have to look across the rest of the life cycle.” This lifecycle approach targets pollution points much earlier in the chain—during prescribing practices, patient usage decisions, and the return of unused medication packages to pharmacies rather than discarding them.
Proponents of this strategy emphasize that it does not mean asking patients to stop taking necessary treatments. Instead, doctors could weigh environmental impacts when choosing between medications, while health systems and patients could prevent surplus drugs from entering the ecosystem.
Pathways and Persistence of Chemical Pollutants
Pharmaceuticals enter the Baltic Sea through multiple pathways, including household and hospital wastewater, discharges from pharmaceutical manufacturing sites, agricultural runoff, and land-based sources. Companion animals also contribute when their waste is improperly disposed of. A decade-old report by UNESCO and the Baltic Marine Environment Protection Commission estimated that wastewater treatment plants release roughly 1,800 tonnes of pharmaceuticals into the Baltic annually. Most of these facilities lack a fourth treatment stage specifically engineered to remove pharmaceutical residues.
Once introduced, these substances can persist for years. Carbamazepine, a prescription medication used for epilepsy, nerve pain, and bipolar disorder, has been repeatedly detected across the Baltic. “It takes almost three and a half years for it to break down into half,” Nekoro explained, highlighting how slow breakdown rates lead to dangerous accumulation.
Impacts on Marine Wildlife and Ecosystem Health
According to Björn Wettermark, professor of pharmacoepidemiology at Uppsala University who leads the research project, the primary concern is not that people will be harmed by swimming in the water—aside from risks related to antimicrobial resistance. Rather, scientists worry about non-target organisms. Pharmaceuticals can trigger feminisation in fish and frogs, disrupting entire populations. Meanwhile, the Baltic blue mussel (Mytilus edulis), a keystone species responsible for water filtration, suffers from reduced energy for metabolism and growth when exposed to certain painkillers. These pharmaceutical pressures compound existing crises like eutrophication, where nutrient over-enrichment depletes dissolved oxygen.
Rational Prescribing as a Preventative Tool
To combat these persistent contaminants, researchers advocate for rational prescribing habits. Kristina Garuolienė, a researcher at Vilnius University, pointed out that alternative medications can sometimes be utilized without compromising patient care. “That is turning to rational prescribing; when doctors are prescribing medicine, they have to also think about which medicine is not dangerous to the environment,” she told Euronews. By shifting clinical focus upstream to prescription habits and proper disposal, scientists hope to establish a viable defense for one of the world’s most troubled inland seas.
