Leaching of active components from preservative-treated timber - Ongoing research: Status after approx. 4 months’ out-door exposure
The Danish Technological Institute is together with manufacturers of active ingredients and formulators of wood preservatives running a project aiming at finding realistic leaching rates from preservative treated wood in hazard class 3 (above ground). The project is focussed on developing a field trial method for investigating leaching.
According to BPD hazard assessment has to be carried out for biocide products and a part of that includes possible environmental impact of preservative treated wood. Leaching of active ingredients from treated wood has to be measured and assessed. Several organisations (CEN, OECD and others) are in progress of developing laboratory leaching test methods.
In order to give more realistic data for leaching of active ingredients it is important to study natural exposure. According to recent publications (IRG/WP 01-50171), it appears to be a significant difference between natural leaching and laboratory leaching methods and a relative comparison is, therefore, needed.
Data from close to practice applications are important in order to support products in the BPD. Furthermore, the results are needed to provide benchmarking data to allow other laboratory or accelerated leaching data to be put into perspective. The results from the project are intended to serve as part of the basic documentation for leaching of active ingredients in hazard class 3.
Panels are exposed outdoors under natural conditions at the field trial at Danish Technological Institute and the leachate is collected and monitored by chemical analysis of the active ingredients. The project is ongoing and the paper presents results from approximately 6 months of exposure. The study includes commercially available organic and in-organic fungicides using 4 different application methods: pressure-, vacuum-, flow-coat- and supercritical treated wood. Different test set-ups are investigated and the results obtained from outdoor exposure will be compared with a laboratory test method (CEN/OECD). Furthermore, the laboratory method suggested by CEN/OECD is evaluated and suggestions for improvement are stated.
Keywords: Leaching, field trial, triazole, IPBC, copper-HDO