Impact of antifouling paint regulation on copper and zinc loads from leisure boats in Swedish waters

The Baltic Sea, designated as a Particularly Sensitive Sea Area, hosts an extensive recreational boating sector, with Sweden contributing a substantial share due to its long coastline and high number of leisure boats. Antifouling coatings used on these vessels are sources of copper and zinc pollution, making it essential to identify where emissions occur and how biocide regulations affect environmental loads. To this end, this study mapped all boat berths along the Swedish coast to determine the number and spatial distribution of recreational vessels. Combined with release rate data for commercially available coatings, current inputs of copper and zinc to Swedish coastal waters from the nearly quarter-million leisure boats were estimated at 22.1 and 17.1 tons/yr, respectively. Copper load distributions varied geographically depending on boat density, permitted paint types and water salinity, with the more saline west coast accounting for the largest share (83%). Comparison with other coastal copper sources revealed antifouling coatings on leisure boats and ships to account for a significant proportion (32%) of the total yearly input. Scenario analysis further revealed that copper loads from current leisure boat products exceed nearly three-fold the maximum permissible level of the environmental risk assessment (8.8 tons/yr) that granted these products market approval (Scenario 1). However, enforcement of the updated European Union environmental risk assessment procedure (Scenario 2) could reduce copper loads substantially (to 8.0 tons/yr), if implemented correctly.