Anwendungen von Bioziden in Materialien für Außenanwendungen sind mögliche Quellen für Biozide in Umweltkompartimenten infolge von witterungsbedingten Auswaschprozessen. Im Bericht werden Leachingprozesse und -parameter als auch Methoden zu deren Untersuchung unter Labor- und Freilandversuchsbedingungen beschrieben. Vorteile und Grenzen der verschiedenen Herangehensweisen zur Untersuchung von Leachingprozessen werden diskutiert. Standardisierte Auswaschtests sowie in der Fachliteratur publizierte Auswaschexperimente werden zusammenfassend dargestellt. Es wird beschrieben, wie Leachingdaten gemäß Technischem Leitfaden zur Biozidprodukten-Richtlinie 98/8/EG für eine Risikobewertung genutzt werden. Ein alternativer Ansatz zur mathematischen Modellierung von Leachingtest-Daten wurde erprobt und wird im Bericht erläutert. Potentiell lassen sich mit dem vorgeschlagenen Ansatz bestimmte gegenwärtig auftretende Schwierigkeiten bei der Risikobewertung umgehen.
Applications of biocides in outdoor materials are potential sources of biocides in environmental compartments due to leaching processes under weathering conditions. Leaching processes and parameters as well as methods to investigate leaching processes under laboratory and semi-field conditons are described in the report. Benefits and limitations of different test approaches are discussed. Standardised leaching tests as well as leaching experiments reported in scientific literature are listed. The application of leaching data for risk assessments according to the Technical Guidance Documents for the Biocidal Products Directive (98/8/EC) is described. An alternative approach for mathematical modelling of leaching data was tested and is Explained in the report. Certain difficulties that currently appear during risk assessments may be circumvented by the proposed approach.
Background: Biocidal products can be sources of active substances in surface waters caused by weathering of treated articles. Marketing and use of biocidal products can be limited according to the European Biocidal Products Regulation if unacceptable risks to the environment are expected. Leaching of active substances from treated articles was observed in field experiments to obtain information on leaching processes and investigate the suitability of a proposed test method.
Results: Leaching under weathering conditions proceeds discontinuously and tends to decrease with duration of exposure. It mainly depends on the availability of water, but is also controlled by transport processes within the materials and stability of the observed substances. Runoff amount proved to be a suitable basis to compare results from different experiments. Concentrations of substances are higher in runoff collected from vertical surfaces compared to horizontal ones, whereas the leached amounts per surface area are higher from horizontal surfaces. Gaps in mass balances indicate that additional processes such as degradation and evaporation may be relevant to the fate of active substances in treated articles. Leached amounts of substances were considerably higher when the materials were exposed to intermittent water contact under laboratory conditions as compared to weathering of vertically exposed surfaces.
Conclusions: Experiences from the field experiments were used to define parameters of a procedure that is now provided to fulfil requirements of the Biocidal Products Regulation. The experiments confirmed that the amount of water which is in contact with exposed surfaces is the crucial parameter determining leaching of substances.