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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


Étude de l'impact d'un xénobiotique sur le milieu aquatique: Approche méthodologique
1990 - IRG/WP 3586
L'action de xénobiotiques sur les communautés vivantes des écosystèmes lénitiques a été abordée à des échelles spatiotemporelles différentes. Dépassant le niveau des tests monospécifiques, nous avons effectué des essais en laboratoire sur des microcosmes contenant des végétaux ( Lemna minor ) et des bactéries et également sur des bassins de quelque m³ contenant une grande variété d'organismes. Les essais ont porté jusqu'à présent sur le Pentachlorophénol; ils seront poursuivis prochainement sur d'autres composés. Les résultats obtenus au laboratoire se sont avérés être transposables aux effets obtenus dans les bassins: le développement de souches bactériennes résistantes au PCP et l'inhibition de l'activité photosynthétique des différents groupes de végétaux constituent les principaux résultats de la contamination par le fongicide. Ces effets reposent sur les caractéristiques de dispersion et d'accumulation du produit étudiées par ailleurs. Il s'avère que l'approche méthodologique multidimensionnelle utilisé içi est très efficace et elle sera utilisée pour vérifier les effets d'autres xénobiotiques sur la structure et le fonctionnement des écosystème aquatiques.
G Blake, G Merlin


The effect of certain wood extractives on the growth of marine micro-organisms
1977 - IRG/WP 438
S E J Furtado, E B G Jones, J D Bultman


Improvements of monitoring the effects of soil organisms on wood in fungal cellar tests
1996 - IRG/WP 96-20093
Accelerated testing the durability of preservative treated timber in a so called "fungal cellar" or "soil-bed" to evaluate its performance in ground contact is widespread practice. In order to obtain a more accurate and reproducible estimate of preservative performance, several institutes, among them the BAM in Berlin, have routinely carried out static bending tests in addition to visual examination. These tests were usually performed with a defined maximum load or deflection path regardless of the remaining degree of elasticity of the test specimens. Recent studies at the BAM revealed that by modifying the method, i.e. by restricting the applied load to the non-destructive interval for each individual test specimen, the calculated modulus of elasticity (MOE) reflect the changing strength properties caused by biological deterioration and allow within a relatively short time valuable predictions on the service life of the treated timber in soil contact.
I Stephan, S Göller, D Rudolph


IRG - wood preservation - annual report 1999; wood preservation in Slovak Republic
2000 - IRG/WP 00-40192
This report gives basic information about wood preservation in Slovak Republic, related to the wood preservation research and education, to the most important wood-destroying organisms, to the wood preserving industry, and also to the problems of standards, market and environment.
L Reinprecht


Vertical distribution of fouling and wood-boring organisms in the Trondheimsfjord (Western Norway)
1981 - IRG/WP 467
Results of a detailed study on the vertical distribution of fouling and wood-boring organisms of Trondheimsfjord at an interval of 3 m from intertidal level to a depth of 30 m, has been presented, based on data collected from two series of panels, exposed from 15 March 1977 to 15 July 1977 (Series I) and from 22 July 1977 to 13 March 1978 (Series II). The intensity of fouling generally decreased with increasing depth. Quantitatively, fouling was heavy on panels of Series I more than on Series II, although species-wise it was more heterogenous on panels of Series II. The bulk of the fouling was constituted by Balanus crenatus, Laomedia sp., Mytilus sp., Modiolus sp. and Hiatella arctica. Incidence of borers and the resultant destruction of timber were heavier on panels of Series II than on those of Series I. The influence of the period of exposure on the above pattern of infestation by foulers and borers has been discussed. Psiloteredo megotara concentrated at the upper levels up to a depth of 15 m, with more settlement between 3 m to 9 m depth. Although Xylophaga dorsalis was present on panels from 3 m to 30 m depth, their intensity abruptly changed from 9 m onwards and continued to increase with increasing depth, with a maximum number near the mud level at 30 m. Attack of Limnoria lignorum also was heavy at the mud level. On the same panel, while Psiloteredo megotara preferred to settle in more numbers on the lower surface, Xylophaga dorsalis did so on the upper silted surface. The importance of such selective vertical incidence of different borers and their co-operation in the destructive activity have been stressed from the point of wood destruction in the Tronheimsfjord. The rate of growth of Balanus crenatus, Laomedia sp., Psiloteredo megotara, Xylophaga dorsalis, and Xylophaga praestans in relation to depth has been presented. For Balanus crenatus rate of growth decreased with increasing depth, while for Laomedia the same increas with depth up to 12 m and declined thereafter. In accordance with its depth preference, Psiloteredo megotara registered faster growth between 3 to 15 m depth. In the case of Xylophaga dorsalis, the size of the shell valve and burrow increased with increasing depth up to 24 to 27 m and then showed a slight decline at 30 m. Factors influencing the growth-rate at different levels have been discussed. The results on the vertical zonation and rate of growth of the wood-infesting organisms encountered, have been compared with relevant literature published earlier.
L N Santhakumaran


Wood-attacking organisms in Brazil
1982 - IRG/WP 1168
Lists of the main wood-attacking beetles, termites, fungi and marine borers in Brazil are presented with the respective wood species from which they were collected.
M S Cavalcante


Utility, deterioration and preservation of marine timbers in India
2005 - IRG/WP 05-40314
Timber is extensively used in India in the marine environment for various purposes due to its several advantages over modern materials. Infact, its use is increasing in recent years, finding wider and wider applications and this scenario is not going to change in the near future. Though, the bio-deterioration problem is found very severe in tropical waters, still indigenous methods are widely employed for the protection of fishing craft and the present level of chemical treatment is well below 5% of total timber used. This is due to socio economic problems of the potential timber user groups, unavailability of treatment plants in the coastal areas, lack of awareness in user groups, etc. In this paper, types of fishing craft used in the country, timber uses in the marine environment, bio-deterioration losses, research conducted on bio-deterioration aspects at various places and methods applied for the protection of wooden structures are presented.
B Tarakanadha, M V Rao, M Balaji, P K Aggarwal, K S Rao


Effects of timber surface properties and dipping conditions on uptake of antisapstain actives from two aqueous suspensions, and ultimate effects on efficacy against mould and staining organisms
1995 - IRG/WP 95-30073
Green-off-saw rough sawn Pinus elliottii (slash pine) boards were dipped in aqueous suspensions of two antisapstain formulations, and the resultant surface retentions of active ingredients MTC (methylene bisthiocyanate), CTL (chlorothalonil) or TCMTB (2(thiocyanomethylthio)benzothiazole) were monitored by chemical analysis. Surface retentions increased with suspension concentration and surface roughness, and decreased with initial timber moisture content. Dipping time beyond 20 seconds, timber basic density and earlywood content had little effect. Relatively low surface retentions, produced by dipping smoother boards with higher initial moisture contents, provided lower protection against mould and stain during seasoning than higher retentions. Equations describing the effect of surface retention on efficacy were developed for both formulations, and retentions providing complete protection under the conditions of the test were determined.
M J Kennedy, T L Woods


Creosote movement from treated wood immersed in fresh water: Initial PAH migration
2003 - IRG/WP 03-50201
Creosote has a long history of successful use as a wood preservative, but polycyclic aromatic hydrocarbons (PAHs) in this preservative have raised environmental concerns, particularly when creosote-treated wood is used in aquatic environments. A number of models have been developed to predict the risk of creosote use in aquatic environments, but one limitation of these models is a lack of data on the initial rates of creosote migration from treated wood. We examined the effect of flow rates on creosote migration from freshly treated wood immersed in fresh water. Creosote component levels declined to a steady state within 7 days, suggesting that creosote migration decreased sharply after an initial spike. The data will be used to enhance existing predictive models.
Sung-Mo Kang, J J Morrell, J Simonsen, S T Lebow


Effects of some essential oils on wood destroying organisms
1993 - IRG/WP 93-10047
Three wood destroying fungi: Botryodiplodia theobromae Pat. (stain), Gloeophyllum sepiarium (brown rot), and Pycnoporus sanguineus (white rot) were exposed to six plant essential oils: the peppermint, kaffir lime or leech lime, lavender, tarragon, holy basil, and the eucalyptus. The peppermint oil showed most effective to inhibit fungal growth, while eucalypus oil was the least effective. The other oils inhibition rate varied according to the species of fungi. In the experiment of the powder post beetles Heterobostrychus aequalis Waterh., the insects were killed within three days in the oil of tarragon, eucalyptus and holy basil, while in lavender oil they could live to ten days the same as controls. But on the contrary in the oil of peppermint and kaffir lime, some of them could even lived longer than the controls.
K Atisongkroh, C Anantachoke, P Lekuthai, S Pensook, T Kittirattrakarn


Bacteria as possible organisms for biological control of blue stain
1988 - IRG/WP 1339
The article discusses the possibilities of biological control of blue stain. Besides using some antagonistic fungi, the possibility of using antagonistic bacteria, which offer still greater possibilities, should not be overlooked. Tests performed have shown that some bacteria from the genera Streptomyces and Pseudomonas have a strong antagonistic effect of blue stain.
R Benko


Practical testing of wood preservatives to prevent weathering damage and infection by micro-organisms on spruce and pine
1989 - IRG/WP 3530
Brush application, is generally used to prevent wooden window frames from decay caused by influence of weathering and fungi. Accordingly 10 boards of pine (Pinus sylvestris) and spruce (Picea abies) were treated with 10 commercially used wood preservatives. The efficiency of fungicides by using chiptest and blue stain test (EN 152), the effectiveness against weathering as well as the course of colonization of microfungi were measured on boards, that had been hurted by sawing. Results after one year's exposure showed that neither the normally required amount of 250 ml/m² nor the effective depth of penetration of the fungizidal equipment had been realized by using brush application. The smaller the permeability of the coating system, the more likely ideal conditions for the growth of fungi (e.g. basidiomycetes) are provided, answering hurtings of the coating and moisture contents of more than 30%. The variety of fungi (on pine 32 and on spruce 17 species) can be a result of anatomical differences and distinguished compounds of the wood species. After 24, respectively 36 weeks of exposure the frequent occurrance of basidiomycetous yeasts (Cryptococcus albidus, Rhodotorula mucilaginosa), blue stain fungi (Aureobasidium pullulans, Hormonema dematioides), Epicoccum nigrum, Alternaria alternata and Phoma species was noted.
R Gründlinger, O Janotta, H Melzer, K Messner


Effect of leaching temperature and water acidity on the loss of metal elements from CCA treated timber in aquatic conditions. Part 2: Semi-industrial investigation
1995 - IRG/WP 95-50040-13
In continuation of previous leaching research on the quantification and modelling of metal elements released from CCA treated timber, a series of experiments has been carried out dealing with the influence of temperature and pH of the relative aquatic environment. The leaching method used is the Dutch prestandard for building materials, a long term static leaching test simulating practical bank-shoring situations. Parameters of study are type of fixation, wood species and specimen profiles. With decreasing water temperature, significantly less leaching of copper, chromium and arsenic is observed. An outdoors/indoors temperature ratio of 0.7 could be established. Increasing acidity of the leaching water mainly enhances the release of copper, whereas chromium and arsenic show a minimum leaching tendency at neutral pH. Both conditioning chamber fixation and steam fixation prove to be effective in fixing the metal elements in the wood substrate. With steam fixed timber, however, a higher loss of copper is observed during the early leaching cycles, due to the presence of copper salts on the wood surface. With regard to specimen profiles, boards in comparison with posts demonstrate a remarkable resistance to leaching of active ingredients, presumably due to the different heartwood/sapwood distribution and the specimen dimensions. In conclusion, the observations made confirm the results obtained from previous leaching studies. Converting the emission data into leaching fluxes, a highly correlated double logarithmic flux formula is regarded the best tool for curve fitting, however, for a limited time span. Other models which are more suitable for extrapolation of emitted quantities over a longer period of time are still under investigation. Likewise, proprotional metal ratios versus retention levels highlight the relativity of experimental data obtained with standard emission tests.
G M F Van Eetvelde, W J Homan, H Militz, M Stevens


Laboratory simulation of leaching from creosote treated wood in aquatic exposures
2000 - IRG/WP 00-50157
Creosote has a long history of use as a preservative particularly in industrial wood products, but its use has come under increasing scrutiny as a result of concerns about its potential effects on aquatic and terrestrial non-target organisms. Despite its long use, there is relatively little data on the rates of creosote loss in many exposures. In this report, we describe small scale leaching tank procedures for evaluating migration from creosote-treated Douglas-fir lumber exposed at 35°C under 0 flow rate conditions. Creosote component concentrations in the water column were quantified using solid phase microextraction and gas chromatography. As expected, migration rates were higher for lower boiling point fractions. Leaching in the first eight hours followed a linear relationship for acenaphthene, dibenzofuran, fluorene, phenanthrene and fluoranthene. Chemical concentrations arrived at a steady state after 24 hrs of leaching. Concentrations of all creosote components tested tended to be lower than their reported water solubilities, suggesting that other factors were influencing migration. Further analyses of the leaching system are planned. The results will be used to expand a model that simulates creosote loss from treated wood in flowing fresh water.
Ying Xiao, J Simonsen, J J Morrell


The attack of naturally durable and creosote treated timbers by Limnoria tripunctata Menzies
1995 - IRG/WP 95-10132
Limnoria tripunctata was found tunnelling in creosote treated Douglas fir (Pseudotsuga menziesii) pilings and naturally durable greenheart (Ocotea rodiaei) gate seals at two sites on the south coast of the United Kingdom. Examination of thc creosote-treated wood showed that Limnoria tunnels were concentrated at a depth of 2-3 cm from the timber surface, where creosote loading was lower. Fewer tunnels occured in the heavily creosoted outer zone. Sections through Limnoria tunnels in wood fixed on site were examined using the scanning electron microscope (SEM). These studies showed that S2 layers of wood cell walls adjacent to Limnoria tunnels were decayed by tunnelling bacteria in many cases. Examination of greenheart seals showed that Limnoria tunnelled to a depth of 1.5 cm, in the soft-rot decay zone. The heads of the Limnoria tunnels also penetrated "sound" wood to a depth of 2 cm. Examination of sections through Limnoria tunnels showed that wood cells adjacent to tunnels were decayed by both soft-rot fungi and tunnelling bacteria. In addition, a range of prokaryotes and protoctists were attached to tunnel walls in this instance. The size of bitemarks along the tunnel walls suggested Limnoria would ingest a range of these micro-organisms along with the wood substrate. Gut contents of Limnoria fixed at both sites were screened for microorganisms using the SEM. This study failed to show micro-organisms on the surface of wood particles during gut transit, which suggested that ingested microbes were digested by Limnoria.
A J Pitman, G S Sawyer, G F Daniel


Studies on the destruction by marine wood boring organisms of fishing boats in the Eastern Black Sea of Turkey
1977 - IRG/WP 427
The present paper concerns the problem of fishing boats which are attacked by wood boring organisms in the Black Sea of Turkey. The aims of this study are: 1) to identify the marine wood boring organisms attacking fishing boats in the Northern Black Sea of Turkey; 2) to identify the wood species that are used in boat building construction and assess their durability; 3) to assess the degree of attack of the marine wood boring organisms and to evaluate the protection methods and chemicals currently applied to the fishing boats.
R Ilhan, O A Sekendiz


Co-operative work on the performance of treated timber in ground contact
1975 - IRG/WP 344
At the 6th meeting of The International Research Group on Wood Preservation in Vienna, it was decided to approach all interested parties in order to: collate available information, set up collaborative work and to stimulate research on the performance of treated timber, especially hardwoods, in ground contact. In recent years, considerable concern has been expressed about the performance of preservative treated hardwoods in ground contact. Unexpected failures of seemingly well treated hardwoods to soft rot has stimulated work at several research centres. Ideas and theories are beginning to be put forward and the IRG consider that a major effort is required in this area. It has been decided to direct this effort into 2 main areas: a) In the collation of all existing data held around the world concerning the performance of treated timber in ground contact; and b) In the establishment of a co-operative field experiment to study the performance of treated hardwoods. It is hoped that this field experiment will also stimulate related research which can be related to the field results.
D J Dickinson, J F Levy


Wood preservation in Kenya
2000 - IRG/WP 00-40190
Focussing an Wood Preservation in Kenya, the Report discusses and elaborates on Education and Training, Research, Wood deteriorating organisms, Treatment Plants and Processes, Preserving Chemicals, Specifications, Markets, Health and Safety and Environmental issues. Education and Research is limited to one Institution only, other Institutions involved with the properties and utilization of wood hardly touches Preservation. Publications and results of Research Projects over the years have emanated from that Institution. Conferences have not been held for a long time in the country. Fungi, insects, including termites, and Marine borers, are all present in the country. The amount of untreated or poorly treated wood lost through the activities of these organisms is substantial. Treatment is usually of a general nature, assuming that Schedules used will protect timber against all agents of decay. The Kenyan Wood Preservation Industry, now 50 years old and with some 27 Plants around the country, has not explored other Wood Preserving Chemicals or Treatment methods. The four Preservatives used are still CCA, Creosote, BFCA and PCP. The Bethel Process is used by all pressure Plants (CCA and Creosote), with only one immersion Plant (BFCA and PCP). Eucalyptus, Acacia,Cypress and some are the species commonly treated, mainly for the local market with some exports. Schedules have not been properly worked out for different end uses. Transmission, Telegraph poles and Fencing posts comprise the bulk of timber treated, with smaller amounts of Construction timber and Horticultural poles. The four Chemicals used are of foreign origin, imported by Treatment Plants. Apart from a few Standards formulated by the Kenya Bureau of Standards (KBS), there are no other Standards or Codes of Practice to guide the Industry and Users of treated timbers. Specifications have not been fully worked out. The KBS is the only Authority responsible for Quality Control and Certification. Health and Safety of Plant operatives is not of major concern. Problems associated with Toxic Preserving Chemicals in the environment has not been fully addressed yet.
R Venkatasamy


Description of a trial with wood preservatives against marine wood boring organisms
1975 - IRG/WP 412
Wood situated in sea water along the Atlantic coasts of the Nordic countries is attacked by marine wood boring organisms. Timber constructions in these waters therefore must be preservative treated. In order to evaluate the effect of various preservatives against marine wood borers, the Nordic Wood Preservation Council (NWPC) organized a rather extensive trial in 1972. In the absence of and while awaiting international standard methods for testing preservatives it was felt that there was a need for a Nordic standard method. The 1972 trial was consequently planned and performed in close cooperation with the standardisation work. The complete standard method was published by NWPC in 1973 (NWPC Standard No. 1.4.2.2/73).
E Norman, B Henningsson


Vertical distribution of fouling and wood-boring organisms in the Trondheimsfjord (Western Norway)
1981 - IRG/WP 476
Results of a detailed study on the vertical distribution of fouling and wood-boring organisme of Trondheimefjord at an interval of 3 m from intertidal level to a depth of 30 m, has been presented, based on data collected from two series of panels, exposed from 15-3-1977 to 15-7-1977 (Series I) and from 22-7-1977 to 13-3-1978 (Series II). The intensity of fouling generally decreased with increasing depth. Quantitatively fouling was heavy on panels of Series I than on Series II, although species-wise it was more heterogeneous on panels of Series II. The bulk of the fouling was constituted by Balanus crenatus, Laomedia sp., Mytilus edulis, Modiolus sp. and Hiatella arctica. Incidence of borers and the resultant destruction of timber were heavy on panels of Series II than on those of Series I. The influence of the period of exposure on the above pattern of infestation by foulers and borers has been discussed. Psiloteredo megotara concentrated at the upper levels upto a depth of 15 m, with more settlement between 3 m to 9 m depth. Although Xylophaga dorsalis was present on panels from 3 m to 30 m depth, their intensity abruptly changed from 9 m onwards and continued to increase with increasing depth, with maximum number near the mud level at 30 m. Attack of Limnoria lignorum also was heavy at mud level. On the same panel, while Psiloteredo megotara preferred to settle in more numbers on the lower surface, Xylophaga dorsalis did so on the upper silted surface. The importance of such selective vertical incidence of different borers and their cooperation in the destructive activity have been stressed from the point of wood destruction in the Trondheimsfjord.
L N Santhakumaran


On the effectiveness of fumigants against wood-destroying insects and fungi in wooden cultural property
1993 - IRG/WP 93-10030
Based on a survey of the history of the use of fumigants the actual agents are mentioned in relation to their biogenic effect on wood-destroying insects and fungi as well as their corrosive behavior on cultural property. Furthermore the conditions for the use of reactive fumigants in buildings are discussed. Trials to control wood-destroying insects and fungi by nitrogen and bromomethane are the main aspect. The extermination of larvae of wood-infesting insects depends on the time of diffusion of nitrogen through wood. The mycelium of the tested Basidiomycetes is eradicated by a dose of 25 mg/l bromomethane, but the dose for the tested Ascomycetes has to be more than 50 mg/l bromomethane.
W Unger, A Unger


Protection of southern pine using N,N-Napthaloylhydroxylamine: Field tests, soft-rot cellars and aquatic bioassay leach testing
1999 - IRG/WP 99-30204
Recent environmental restrictions are limiting the use of broad-spectrum biocides for wood preservation. There is an urgent need for new, sharply targeted, environmentally benign wood preservatives. N'N-Napthaloylhydroxylamine (NHA), a water-soluble calcium-precipitating agent, has been shown to inhibit decay by brown-rot and white-rot fungi in soil-block tests and prevent damage by Eastem subterranean termites under lab conditions. In order to further evaluate the capacity of NHA to prevent decay and termite damage, SYP stakes were pressure treated with three concentrations of NHA (0.1, 0.5 and 1.0%) and CCA (1.0%) and placed in-ground at the Harrison Experimental Forest, Gulfport, Mississippi, in June, 1997. Similarly, treated sticks were placed in soft-rot fungal cellars at FPL. One percent NHA-treated stakes were also leached for 72 hours in water and the leachates tested by an acute, five dilution bioassay using Ceriodaphnia dubia in EPA Protocol 600/4-90/27F. Results to date: 1) NHA stakes (0.5 and 1.0%) are as durable as CCA; 2) NHA does not inhibit soft-rot fungi and, 3) NHA is a relatively benign molecule with LD50 130-fold less than copper for C. dubia.
D M Crawford, F Green III


Qualifying ecotoxicity research on tropical hardwood leachates
1997 - IRG/WP 97-50096
Almost as a rule, quantification and identification of various types of environmental contamination is grounded on chemical evaluation principles. Yet for monitoring surface water pollution, aquatic bio-assays may provide a more direct way to assess the potential hazard of environmental samples. A battery of such tests is experienced onto leachates of tropical hardwoods used in ground and water contact. Four of seven wood species tested exhibited no acute toxic profile, whilst afzelia, afrormosia and mainly merbau revealed a considerable toxicity response for all organisms tested. These results, although at screening level, demonstrate the natural toxicity of particular tropical hardwood extractives towards the aquatic compartment. Hence, a welcome source of information is obtained, so as to weigh the ecotoxicity results previously gathered on preservative treated wood.
G M F Van Eetvelde, P Marchal, M Stevens


Aspects of leaching
1976 - IRG/WP 267
With respect to Document No: IRG/WP/246, and the recommendation that an economic leaching test can be based on a non-changing volume of water (500 ml/block), I would like to relate our experiences with this suggestion. Following 14 days of continuous immersion in de-ionized water it was found that blocks treated with moderate and above concentrations of a preservative gave no problems, but those blocks either having low chemical treatments or none (controls) produced a very healthy growth of slimy fungi and bacteria. Obviously these micro-organisms could be affecting the wood structure, should you wish to subsequently decay the blocks for biological toxicity evaluation. Also the micro-organisms could be degrading or otherwise modifying the preservative under evaluation. Under the old methods of "beaker leaching", with the water being changed daily, the growth of micro-organisms does not appear to be a problem. Any sugars leaching out into the water are removed within 24 hours and therefore the environment does not support their growth. The proposed method may be acceptable for leaching blocks containing a high retention of preservative (as reported in the paper), but as a method generally applicable to a concentration range of retentions, it does not seem to be acceptable. Obviously toxic agents could be added to the leaching water to prevent the growth of such micro-organisms, but this would have unpredictable effects on the wood-preservative-fungus complex under examination. I feel that this situation should be brought to the attention of the members of the IRG Working Group, since a non-biologist might not be aware of what has happened to his test and therefore present erroneous results.
R S Smith


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