Tackling chemical tanker pollution: time for companies to take responsibility
Writer
The Baltic Sea is one of the busiest seas in the world: about 2,000 cargo ships sail the Baltic Sea every moment. Among these, chemical tankers play an important role in transporting raw materials and products for the chemical industry across the sea, but it comes with significant environmental challenges, specifically related to pollution. The Baltic Sea is particularly vulnerable to pollution because of its brackish and shallow water and limited water exchange, which makes harmful substances persist longer in the ecosystem. According to the latest HELCOM HOLAS report handling the ecosystem health of the Baltic Sea, hazardous substances have been identified as the second biggest threat to the sea’s health alongside eutrophication. One identified source of these hazardous substances is the maritime transport of liquid bulk cargoes – that is, chemicals.
When a chemical tanker washes its tanks, hundreds of litres of harmful and hazardous chemicals can end up in the marine ecosystem in one go along with the washing water. After unloading their cargo, chemical tankers often wash their tanks with seawater en route to the next port of loading. International regulations permit the discharge of tank washing waters into the sea under certain conditions. When a ship discharges its washing waters, it must be sailing at least 12 nautical miles (about 22 kilometres) from the nearest coastline in areas of at least 25 metres in depth. In practice, this leads to discharges being concentrated in specific sea areas, such as the heavily trafficked but shallow Gulf of Finland. Current regulations restrict the discharge of tank washing waters into the sea only for the most hazardous substances. However, the release of harmful chemicals, such as carcinogenic benzene; styrene, which is toxic to aquatic organisms; and phenol, which has been shown to have a major impact on the growth of algae and other organisms even in very low concentrations, is still allowed.
Practical solutions to minimize chemical emissions
The chemical industry’s voluntary initiatives have shown promise in reducing these emissions. In John Nurminen Foundation’s Chemical Tanker Project, done in cooperation with the Finnish Transport and Communications Agency Traficom, Coalition Clean Baltic, and the Swedish Transport Agency Transportstyrelsen, we have sought practical solutions together with the Finnish chemical industry and ports to minimize the chemical emissions. For example, for tall oil and styrene, there are already cost-effective ways to treat tank washing waters on land so that cargo residues are reused and do not end up in the sea. In 2023, all Finnish tall oil operators committed to ending tank washing discharges into the Baltic Sea. Some companies had already developed methods for handling washing waters onshore, and best practices were shared across the industry. These efforts demonstrate that voluntary actions can reduce environmental impacts while enhancing corporate responsibility and industry image.
Despite these efforts, obstacles still exist. International maritime regulations are often less stringent than national laws, allowing certain emissions at sea that would be prohibited on land. Monitoring activities on international waters is challenging, and vessels responsible for illegal discharges are rarely held accountable. The cumulative impact of various chemical discharges, “chemical cocktails”, on the sea and its organisms is not yet fully understood. At the moment, there is insufficient data on the types and quantities of harmful substances entering the sea from vessels, making maritime traffic a blind spot in environmental monitoring. But one thing is sure: different chemicals are being discharged into the Baltic Sea daily. To tackle the problem entirely, stricter international regulations are essential. These must include prohibiting tank washing water discharges, strengthening monitoring systems, and ensuring compliance through more effective enforcement.
To address these issues, the John Nurminen Foundation encourages the chemical industry to adopt a broader perspective that extends beyond factory emissions to encompass the entire transportation chain. Responsible companies should ensure that the ships and terminals they utilize do not contribute to the discharges of harmful substances into the sea. Taking proactive measures today by exceeding the legal minimum requirements not only benefits the Baltic Sea but also prepares the industry for the likely regulatory changes happening in the near future.
The blog was firs published on a discussion forum Baltic Rim Economies (BRE), 1/2025. BRE is published by Centrum Balticum and deals with the development of the Baltic Sea Region.
Project reduces discharges of harmful substances into the Baltic Sea from tank washing on chemical tankers.
