Boat hull paints – a problem for our waters

Copper emissions from antifouling paints should be reduced

A sea harbor with many small sail and motor boats.Click to enlarge
Antifouling paints are reapplied every one to two years because the biocides are washed out.
Source: Dr. Michael Feibicke / UBA

According to current estimates, about 70 tonnes of copper in antifouling paints applied on pleasure craft are polluting Germany's surface waters every year. Paints and coatings which contain biocides are often used to protect against unwanted growth of algae or mussels. Copper is the most commonly used biocide in antifouling paints. Copper emissions from paints amount to about 19 per cent of total copper emissions to surface waters in Germany. The impact is ecotoxic for bacteria, algae, crayfish and fish. The German Environment Agency (UBA) recommends alternative hard coatings and mechanical cleaning, for example with underwater brushes, or the use of alternative coatings with no biocides. Regional differentiation and the documentation of applications, advisory services for users and official monitoring of copper can help to reduce copper pollution.

Copper is exceeding the limit of the environmental quality standards of the Surface Water Ordinance (OGewV), which describe good ecological condition of surface waters, at eleven per cent of official measuring stations. Paints which contain copper are often used on the hulls of pleasure craft. This is why it is appropriate to take measures to reduce water pollution here. A few examples from Scandinavia show how it can be done: Sweden allows only products with reduced copper content for most craft on the Baltic Sea, and all use of biocidal agents in antifouling paints is prohibited on inland waters. These regional regulations might serve as a model which Germany could follow. Only one small region in Schleswig-Holstein has banned the use of environmentally harmful, biocidal antifouling paints.

It is difficult to implement such regional differentiations when it comes to product approval under the EU Biocidal Products Regulation. Germany should therefore – as Sweden does – develop its own regulations which involve all the authorities at the federal and state levels of government, producers of antifouling paints, pleasure craft associations, marina operators and pleasure craft owners.

Biofouling on boat hulls is less intensive on inland waters, which is it is possible to do entirely without the use of biocidal products. Instead, hard coatings can be applied to boat hulls which are cleaned with underwater brushes. For the Baltic Sea coatings with low copper content and those which have lower copper emissions to water are considered sufficient. In the North Sea, however, the application of antifouling paints is a must.

Depending on the different regional requirements, producers should employ a three-tier traffic light labelling system for their paints (North Sea, Baltic Sea, inland waters) to orient users when making their choice. Users should keep a log of the intervals of their paint reapplications. Portable hand-held devices are available for the authorities to monitor the copper content on boat hulls.

A new background paper by the German Environment Agency provides comprehensive information about antifouling paints and substance emissions and gives recommendations for environmentally friendly use.  

Umweltbundesamt Hauptsitz

Wörlitzer Platz 1
06844 Dessau-Roßlau