Biocide leaching during field experiments on treated articles

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Material Science

Background:

• Biocidal products can release active substances into surface waters through weathering of treated materials.
• Environmental risks associated with biocidal product use may lead to marketing restrictions under the European Biocidal Products Regulation.
• Field experiments were conducted to study leaching processes and evaluate a proposed test method.

Purpose of the Study:

• To investigate the processes of active substance leaching from treated articles under weathering conditions.
• To assess the suitability of a proposed test method for evaluating leaching.
• To inform risk assessments required by the Biocidal Products Regulation.

Main Methods:

• Field experiments simulating weathering conditions.
• Monitoring of leached active substances in runoff.
• Comparison of leaching from vertical and horizontal surfaces.
• Laboratory experiments with intermittent water contact.

Main Results:

• Leaching is discontinuous, decreases over time, and depends on water availability, material transport, and substance stability.
• Runoff amount is a suitable metric for comparing leaching experiments.
• Substance concentrations were higher from vertical surfaces, but leached amounts per area were higher from horizontal surfaces.
• Leaching was significantly higher under intermittent laboratory water contact compared to field weathering.

Conclusions:

• Field experiment data were used to refine a procedure for the Biocidal Products Regulation.
• The amount of water in contact with exposed surfaces is the primary factor controlling substance leaching.
• Additional processes like degradation and evaporation may influence the environmental fate of leached substances.