Abstract
Laboratory leaching tests on treated wood were performed during a European robustness study in the framework of the validation of a tank leaching test procedure that has been proposed for construction products in order to determine the potential release of dangerous substances which can be transferred to soil and groundwater. The release of substances has to be determined also for materials treated with biocidal products according to the requirements of the European Biocidal Products Regulation. A similar leaching test procedure was already harmonised for treated wood for this purpose. Both test procedures were applied in parallel to wood treated with the same preservative to investigate whether the results of these tests can replace each other. Additional experiments were performed to further investigate unexpected effects of L/A ratio on leaching of copper and duration of storage of treated test specimens. Both procedures generate similar results concerning cumulative emissions of tebuconazole, copper, dissolved organic carbon and total nitrogen. The emission rates with time are in comparable ranges for both leaching protocols. Emissions of copper increased with decreasing L/A ratios. Strong correlation of copper concentrations and dissolved organic carbon as well as total nitrogen concentrations in eluates indicates that this observation is caused by co-elution of copper with organic substances. Duration of storage of treated test specimens affected emissions for the investigated wood preservative. Based on these findings, results from both test procedures can be used to describe leaching characteristics and avoid double testing of treated wood to fulfil the requirements of the European regulations for either biocides or construction products. Leaching of substances from treated wood is a complex process that depends on its chemical composition and ageing processes.
Highlights
Laboratory leaching tests on treated wood were performed during a European robustness study in the framework of the validation of a tank leaching test procedure that has been proposed for construction products in order to determine the potential release of dangerous substances which can be transferred to soil and groundwater
The replicates investigated at conditions stipulated in the current documents for both leaching tests were selected for this comparison
It has to be considered that similar emission rates in TS-2 and OECD 313 experiments mean higher concentrations of these components in the eluates from the OECD 313 experiments, since the standardised liquid volume/exposed surface area (L/A) ratios applied for the comparison were 8 and 2.5 cm3/cm2, respectively
Summary
Laboratory leaching tests on treated wood were performed during a European robustness study in the framework of the validation of a tank leaching test procedure that has been proposed for construction products in order to determine the potential release of dangerous substances which can be transferred to soil and groundwater. The EU member states require that construction works are designed and executed so as not to endanger the safety of persons, domestic animals or property nor damage the environment within the Construction Products Regulation [1]. This includes concern about possible emissions of harmful substances due to contact of construction products with water. A dynamic surface leaching test (DSLT) has been proposed for testing of monolithic materials and described in a Draft Technical Specification (FprCEN/TS 166372:2013 [4], temporarily named TS-2) This procedure is intended to apply for structural timber since it is considered a ‘monolithic product’. It was decided to use wood specimens treated with a wood preservative to assure that methods for the quantification of inorganic as well as organic substances in the eluates were available and that the experiments provide data for the evaluation of the test procedure
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