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On site test for indicative determination of leaching of components of preservatives from treated timber. Part 2: New data on CCA-C, CC and CCB treated timber
1994 - IRG/WP 94-50025
The 'on site test' was published at the IRG meeting in Cannes in February 1993 (IRG/WP 93-50001/12). Since this publication many on site tests were performed parallel to so-called shower tests. The correlation between the test results of the on site tests and the shower test has been established more clearly. For chromium the correlation between both tests is indistinctive of preservative formulation. For copper the correlation differs for CCA on one side and CC's and CCB's on the other side. In some cases the on site test does not correcty predict shower test results. The reasons for this phenomenon are discussed. It can be concluded that the on site test is a roughly indicative test for assessing the leaching of components of preservatives from treated timber. The correlation figures, however, are formulation dependent.
W J Homan

The influence of previous anti-blue-stain preservative treatments on the fixation of CC in spruce
1997 - IRG/WP 97-30134
Freshly cut and kiln dried spruce boards were treated with 4 different anti-blue stain preservatives (ABP). After a period of 10 days allowing the samples to dry and fixate, the samples were treated with CC (chromium, copper formulation) using a vacuum pressure cycle. After impregnation the wood was steam fixed. A submersion leaching test showed differences in the leachable quantity of copper and chromium. When related to the retention of both salts after impregnation, no differences could be found between samples previously treated with anti-blue-stain preservatives and untreated samples. However, the retention of CC diminished significantly by application of quaternary ammonium compounds.
M Van der Zee, W J Homan

Water-borne wood preservatives against marine borers. Results from NWPC marine trials started in 1972 and 1976
1990 - IRG/WP 4162
The paper presents the results from NWPC (Nordic Wood Preservation Council) marine trials started in 1972 and 1976. The trials are carried out according to the NWPC Standard No. "Marine test - a test against marine wood boring organisms in sea water". The test site is Kristineberg Marine Biology Station on the west coast of Sweden. The wood blocks used in the trials were made from sapwood of European redwood (Pinus sylvestris L.). European beech (Fagus sylvatica L.), European birch (Betula spp.) and Norway spruce (Picea abies (L.) Karst) were also used to a minor extent. In all, 19 water-borne wood preservatives were tested. The preservatives consisting of copper-chrome, copper-chrome-arsenic, copperchrome-boron, copper-chrome-phosphorus and tributyltin oxide gave best performance. The ammoniacal copper preservatives failed to protect the wood against marine borers.
Ö Bergman, C Lundberg

Moisture condition in treated wood exposed outdoors. A progress report
1989 - IRG/WP 3533
Wood treated with water-borne preservatives, mainly CCA (copper/chromium/arsenic), CCB (copper/chrome/boron) or CC (copper/chrome) is often said among users in Sweden to absorb more water than untreated wood. In laboratory tests this statement has not been confirmed but no field tests have been carried out in Sweden to study this phenomenon. In 1986 a project was started to compare water absorption during outdoor exposure between wood stakes of pine (Pinus sylvestris) and spruce (Picea abies) both untreated and treated with different preservatives. For comparison stakes of different species were included as well as painted pine stakes. Equilibrium moisture content in humid environment was tested for untreated pine-stakes and stakes treated with CCA and ammoniacal copper preservatives.
M-L Edlund, C E Sundman

Determination of fixation properties by bioassays - A proposal for the assessment of safety indexes in wood protection
1990 - IRG/WP 3566
In the determination of environmental effects of chemicals tests with fishes, daphnia and algae have proved to be practicable. With respect to wood protection such bioassays are suitable to control effects of treated timber against aquatic organisms. By using the fish-acute-toxicity-test the development of a laboratory test method is described for the checking of the fixation rate of a copper-chromium wood preservative. By this the importance of the observation of a proper fixation period is demonstrated for the use of treated wood in water contact. Estimating ecotoxicological effects of leachable compounds using sensitive bioindicators allows a differentiated determination of environmental risks of impregnated timber. The comparison with the toxic effects of the compounds of a wood preservative are a first step in the assessment of safety indexes in wood protection.
H-W Wegen

Effectiveness of copper/chromium salts as wood preservatives against Limnoria tripunctata Menzies in laboratory tests
1977 - IRG/WP 431
During the last joint meeting of IRG and COIPM a co-operative programme of tests with copper/chromium salts as wood preservatives against marine borers was discussed and agreed. In this connection the results of a laboratory test in the BAM with Limnoria tripunctata Menzies will be of interest. But as the respective paper is written in German (H. Kühne; G. Becker: Laboratoriumsversuche über die Wirkung kupferhaltiger Schutzsalzgemische auf die Holzbohrassel Limnoria tripunctata Menzies) (Material u. Organismen 5 (1970) No 4, 307-319) a comprehensive summary is given in English for IRG-COIPM members.
H Kühne

Microbial decomposition of salt treated wood
1993 - IRG/WP 93-50001-22
Specialized microorganisms which are able to convert fixed inorganic preservatives from treated wood into water soluble components are investigated. A number of brown rot fungi like Antrodia vaillantii have been isolated from cases of damage and examined under unsterile conditions with CCA-, CCB-, CCF- and CC-treated wood at retention levels of at least 50% higher than recommended for wood in ground contact. Depending on the kind of fungus, preservative retention, wood particle size, culture conditions and duration Cr and As can be almost completely leached from the treated wood. Cu reacts with oxalic acid to a compound of limited water solubility.
R-D Peek, I Stephan, H Leithoff

Biological detoxification of wood treated with salt preservatives
1992 - IRG/WP 92-3717
The use of microorganisms that are capable to convert chemically fixed inorganic preservative complexes from impregnated wood waste into watersoluble components is investigated. A number of fungi were isolated from deteriorated and initially well-treated wood. They revealed an exceptionally high production of organic acids (pH 2). The fungi were identified and used together with others of the same genus for experiments under non-sterile conditions on a laboratory scale with CCA-, CCB and CC-treated wood at retention levels of at least 50% higher than recommended for wood in ground contact. As a result Cr and As were leached to more than 90% depending on culture conditions, whereas Cu reacts with oxalic acid to a complex with limited water solubility.
I Stephan, R-D Peek

Soluble nutrient influences on toxicity and permanence of CCA preservatives in wood
1980 - IRG/WP 3144
The influence of soluble carbohydrate and nitrogenous components concentrated at evaporative surfaces of wood on the toxicity and permanence of CCA preservatives has been examined using soil-burial techniques. Nutrient concentrations in lime (Tilia vulgaris Hayne) have been shown to be associated with reduction of toxic limits of preservatives to an extent in which a 100% increase in preservative loading is required to provide adequate protection in the presence of soluble nutrient gradients. Toxic limit reduction was seen to be accompanied by nitrogen increases. The latter were attributed to microbial biomass which suggests a significant involvement of sacrificial colonisation by micro organisms. Preliminary analyses of elemental copper and chrome indicate an associated preservative instability.
B King, G M Smith, A Bruce

Comparison of Temporal Changes in Metal Leaching and Aquatic Toxicity from Wood Treated with CCA and Alternative Preservatives
2005 - IRG/WP 05-50236
This study compares the temporal variation of chemical leaching and aquatic toxicity of wood treated with chromated copper arsenate (CCA) and other copper-based wood preservatives (alkaline copper quaternary (ACQ), copper boron azole (CBA), copper citrate (CC) and copper dimethyldithiocarbamate (CDDC)). Treated wood blocks were leached for 21 days and the leachate collected was analyzed for preservative chemicals and aquatic toxicity. The measured rate of copper leaching was fit using the recently proposed diffusion model for predicting preservative leaching rates. An unpreserved wood sample was tested as a negative control. In general the predicted values for flux rate were on the same order of magnitude as calculated using the experimental data. In natural water, several physical and chemical factors may affect the bio-availability and toxicity of chemicals. Copper concentrations and resulting aquatic toxicity obtained using two natural waters as leaching solutions were found to be lower compared with data obtained using de-ionized water as the leaching fluid.
B Dubey, T G Townsend, G Bitton, H M Solo-Gabriele

Copper based water-borne preservatives: Copper adsorption in relation to performance against soft rot
1987 - IRG/WP 3452
As part of a fundamental study concerned with the performance of copper based water-borne preservatives the adsorption of copper from aqueous solutions by 4 hardwood and 1 softwood species has been studied. Experiments were conducted to determine the influence of solution pH, solution concentration and solution temperature. The results obtained were consistent with an acid form ion-exchange mechanism for copper adsorption. These properties of water-borne preservative solutions containing copper are discussed in relation to hardwood performance against soft rot decay.
P M S Rennie, S M Gray, D J Dickinson

A study of the rate of fixation of various chromium-containing preservatives
1991 - IRG/WP 3653
Denmark, and Scandinavia in general, has perhaps the widest range of approved industrial wood preservative types in the world. As an aid in setting realistic fixation periods, work was undertaken to investigate the rate of fixation of chromium in CCA salt, CCA oxide, CCP, CCB, CC and CCF formulations at summer and winter temperatures. The rate of fixation measured in terms of the concentration of unfixed chromium in liquid squeezed from the wood, was found to vary tremendously, requiring from a few days to several months, for adequate fixation.
L B Sheard

Detoxification of salt impregnated wood by organic acids in a pulping process
1993 - IRG/WP 93-50012
The paper descibes a novel method to detoxify pine wood (Pinus silvestris L.) treated with CCB-, CCF- CC-, and Cu-HDO-type salt preservatives. In the process of biological detoxification organic acids produced by strains of Antrodia vaillantii and other brown rot fungi are used for the dissolution of the previously fixed inorganic compounds. These findings are the basis for applying an acid pulping process (FORMACELL) developed by Nimz and Schone (1992) at the BFH, Hamburg, to detoxify salt impregnated wood waste with a mixture of acetic and formic acid. First results achieved with wood chips from treated poles after approximately 20 years of service life show that the obtained pulp contains less than 100 ppm of Cr and Cu. The pulp properties were neither influenced by the Cr and Cu ions nor by the age of the poles. The extracted quantities of Cr and Cu remain with the lignin whereas the acids are evaporated and recycled in the pulping process.
I Stephan, H H Nimz, R D Peek

The role of chromium in wood preservatives - The situation and new results concerning biological efficacy
2006 - IRG/WP 06-30397
A heavy discussion about the status of chromium-containing compounds in wood preservatives has ensued in the European Union since the Biocidal Product Directive 98/8/EG has come into force.The origin of this discussion is the fact that according to the Biocidal Product Directive chromium trioxide and sodium dichromate have been identified as active ingredients and therefore the placement of wood preservatives containing chromium oxide or sodium dichromate on the market is not allowed after September 1, 2006. In a scientific sense, this is only then valid if the chromium compounds are explicitly to be classified as active ingredients. Chromium compounds were previously considered to be fixatives for the biocides used in conventional chromium-containing salts, particularly for copper. Due to this discussion “active ingredient or not an active ingredient (fixative)”, the European Commission recommended that this question should be answered in a case by case decision based on the data of the products. (European Commission 2005). The verification of which function (active ingredient or not an active ingredient) an individual compound has in a wood preservative formulation is much more complex than the verification of the efficacy of the wood preservative itself. Based on the recommendations of the Commission, research projects were initiated which examined the role of chromium compounds in defined wood preservative salts using a frame-formulation
P Jüngel, H Härtner, E Melcher

The role of chromium in wood preservatives under BPD - a review and the current situation in Europe
2008 - IRG/WP 08-30468
Already during the IRG-meeting in Trømso a paper was presented to give an overview regarding the situation on chromium (JÜNGEL et al. 2006). Already in that year there was an increased attempt to achieve a science-based correct and harmonised solution in Europe regarding the chromium-question by the European Commission. Nevertheless the competent authorities (CAs) and the industry were similarly occupied with the principle question: “Is chromium an active?” and this led to a heterogeneous situation in the meantime. However a harmonisation should be of equal importance for authorities, wood preservative manufacturer, users of the salts and users of impregnated wood. It is time to give a new review regarding the background of this discussion, whereas scientific explanations clarify the complexity of the instinctively simple problem. The current situation in Europe shall be described as well.
P Jüngel, S Hellkamp

Danish wood preservatives approval system with special focus on assessment of the environmental risks associated with industrial wood preservatives
2001 - IRG/WP 01-50166-01
The following is a description of the procedure used by the Danish Environmental Protection Agency to assess the environmental risks associated with preservatives used in the pressure impregnation of wood. The risk assessment covers issues considered to be of significance for the environment and which are adequately documented so as to allow an assessment. Such issues are persistence and mobility in soils, bioaccumulation and the impact on aquatic and terrestrial organisms. Unless required in special circumstances, the assessment does not apply to birds and mammals as the normal use of preservative treated wood is not expected to involve any noteworthy exposure of these groups. Approval of wood preservatives will be based on a general assessment of the environmental risk associated with the normal use of wood treated with the preservative in a realistic worst case situation. The assessment may address other aspects such as disposal and total life cycle.
J Larsen

Finishes for outdoor timbers
1975 - IRG/WP 378

Management of the wood and additives wastes in the wood processing industries: Problematics and technical answers review
1996 - IRG/WP 96-50073
Management pathways for pure wood subproducts are well known and used; but as soon as additives like preservatives, glues, varnishes or coatings are present within the wood wastes, their disposal or valorization becomes more tricky. The different kinds of mixed wood wastes of the wood processing industries, from the sawmill to the furniture manufacture, are identified herewith and their diversity is examined. These wastes can be classified according to their danger characteristics, taking into account the type of additives, their concentration, their availability for the environment, the physical state of the waste. Different disposal pathways are then considered. Combustion, with the possibility of energetic valorization seems the best answer for a major part of these wastes. But this is only possible if good combustion conditions are defined, so that no harmful products are emitted. Moreover, these conditions must be affordable on the technical and economical point of view. Then, some wastes cannot be burned in such a simple way, and need a larger approach, which is presented in this document.
S Mouras, G Labat, G Deroubaix

Proposed method for out-of-ground contact trials of exterior joinery protection systems
1981 - IRG/WP 2157
Methods for testing the efficacy of preservative treatments for exterior joinery are described using the format of a European Standard. Commercially used treatments applied to jointed test units (L-joints) which are then protected by conventional finishes are exposed to normal outdoor hazards out of ground contact. Assessment is made a) by determining eventual failure through decay and b) by destructive examination of replicate treated and untreated units, after increasing time intervals, rating comparative performance in terms of wood permeability increase and the progress of microbial colonisation.
J K Carey, D F Purslow, J G Savory

JWPA method for testing effectiveness of surface coatings with preservatives against decay fungi
1981 - IRG/WP 2164
In 1979 JWPA established a new method for testing effectiveness of surface coatings in accordance with practical use of preservative-treated lumber. Comparing the new testing method with JIS A 9302, a few new trials - size of wood specimen, weathering procedure, and decay-test procedure - are incorporated.
K Tsunoda

Wood preservation in Poland
2004 - IRG/WP 04-30362
Dynamic growth of market demand for wooden elements and articles, generated in Poland increase of interest in industrial preservation. Today, Poland is a substantial producer and exporter of wood made products. Majority of exported wood - approximately 70% - is scotch pine (Pinus silvestris L.), which, due to its natural durability, requires preservation.
A Kundzewicz

Wood preservatives: Field tests out of ground contact. Brief survey of principles and methodology
1976 - IRG/WP 269
This paper contains the following spots: 1.: The general need for field tests. 2.: Interests and limits of field tests in ground contact. 3.: Various methods in use for out-of-ground contact field tests. 4.: Fungal cellar tests are they an alternative to above-ground decay exposure tests? 5.: Conclusions.
M Fougerousse

IRG/COIPM INTERNATIONAL MARINE TEST - to determine the effect of timber substrate on the effectiveness of water-borne salt preservatives in sea-water. Progress Report 2: Report of treatment and installation in Australia
1978 - IRG/WP 440
The purpose of this test and the procedures to be followed have been fully set out in documents distributed by the International Research Group on Wood Preservation and numbered IRG/WP/414 and IRG/WP/420. The prescriptions set out in these two documents have been closely followed.
J Beesley

Field test evaluation of preservatives and treatment methods for fence posts
1985 - IRG/WP 3347
This work presents the field test results after fifteen years exposure of Eucalyptus saligna fence posts treated with six different preservatives and five treatment methods. All the combinations with oil-borne preservatives presented the best results and among the waterborne preservatives, the fence posts treated by immersion method were with the lowest performance in the field test.
G A C Lopez, E S Lepage

Screening potential preservatives against stain and mould fungi on pine timber in Zimbabwe
1995 - IRG/WP 95-30063
The search for environmentally and toxicologically safer chemicals for use in the timber preservative industry against stain and mould fungi has been intensified during the past few years. Results of field tests with two chemicals previously evaluated in the laboratory are presented. The conventional sodium pentachlorophenate was the more efficacious chemical against stain and mould fungi, providing up 90% control at a concentration of 2.5%. A potential alternative, Stopstain a borate-based chemical, gave results only slightly better than the untreated control timber, at a concentration of 5%. Unless the environmental cost and toxicological hazards of traditional chemicals are highlighted the newer and safer chemicals will be reluctantly accepted by industry as they are regarded as being prohibitively expensive.
A J Masuka

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