Antifouling agents are commonly used in protective coatings for recreational craft hulls. They act as a pesticide and prevent the growth of algae, small shells and crustaceans on boats. These coatings must usually be renewed every one to two years since the active ingredients are flushed out over time. A particularly high amount of active ingredients end up in docks when freshly coated boats are launched into the water. Antifouling agents can also accumulate outside of sports marinas and do direct damage to aquatic flora and fauna. The likelihood that this occurs is high in Germany because nearly 80 per cent of the country's inland marinas are either connected to, or actually part of, the adjacent bodies of water.
The UBA therefore commissioned a random sampling of all the currently common active agents in antifouling products at 50 sports marinas located between Flensburg in the north to Lake Constance in the south. The targeted substance was Cybutryn, which is known by the brand name Irgarol and is frequently used in antifouling paints. Irgarol is a biocide which can also inhibit photosynthesis in plants. Since Irgarol is very persistent in the environment its impact is long-lived in bodies of water.
The single measurements in summer 2013 revealed concentrations of Irgarol at 35 of the 50 sports marinas which were above the environmental quality standard established for this chemical in the EU Water Framework Directive. The Directive prescribes that the annual average may not exceed the established value of .0025 micrograms per litre. The values measured at five sites were even above the maximum allowable concentration for Irgarol which the environmental quality standard has defined. That maximum concentration is .016 micrograms per litre and may never be exceeded. Furthermore, one fifth of the investigated sites had elevated concentrations of copper and zinc.
The results confirm other investigations which have traced the substance in relevant concentrations in both coastal and inland waters. UBA's own investigations have demonstrated that some of the measured concentrations in the environment may have negative effects on aquatic organisms.
The UBA advises against the use of antifouling coatings by private individuals. Boat hulls can be kept in good condition without antifouling substances, particularly at many freshwater sites. If one nevertheless chooses to use these coatings one should opt for products whose active substances are quickly degraded in the environment.
Several European countries have already implemented restrictions on the use of or even bans on boat paints which contain Irgarol, or a general ban on the use of antifouling paints with biocides in inland waters. These countries include Denmark, Sweden and Great Britain. In Germany there are only a few isolated instances of regional bans on the use of these coatings, for example in Ratzeburger See in Schleswig-Holstein.
The Federal Environment used aerial photos to assess the numbers of recreational craft nationwide, arriving at a figure of about 206,000 berths in 3,091 sports marinas. This figure does not include small marinas with fewer than six boats. The number of this latter type of marina is estimated to be up to 20,000.
European authorisation of antifouling active agents:
The authorisation of underwater coatings that contain biocidal antifouling agents is governed by the Biocides Regulation (EU) 528/2012. Prior to marketing such products, producer or importers must successfully complete a two-stage authorisation procedure: firstly, the active agent in the biocidal product must be authorised for use within the EU for the intended application; secondly, the biocidal product must either be authorised in a Member State or at EU level before it may be placed on the market and used. A detailed dossier must be submitted in the first stage which documents the substance's properties, its behaviour in the environment and impact on man and organisms. A given EU Member State uses this dossier as the basis of its risk assessment of the active agent. The EU Commission applies this assessment to reach a decision on whether to authorise the substance.
A key part of the procedure with regard to the environment includes a comparison of expected environmental concentration in water (e.g. in sports marinas) with action levels in organisms (e.g. algae, daphnia or fish) derived from ecotoxicological tests. If overall risk to man and the environment is classified as low and if the substance is effective for its intended purpose, it may in principle be used in antifouling products which must then be authorised at national level in the second stage of the procedure. No antifouling product has been authorised to date. All of the antifouling products currently on the market are untested and present due to transitional arrangements.