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Penetration behaviour of different hydrophobic carrier substances for oily wood preservatives in Beech and Scots pine sapwood
2017 - IRG/WP 17-40804
The use of creosote as a wood preservative has a long history. Current areas of application are railway sleepers, transmission poles, timber bridges and marine applications. If the approval for creosote will not be prolonged, alternative wood preservatives will be needed. As the penetration behaviour after pressure impregnation of different alternative oily products in this fields of application is so far little investigated, research has been implemented for hydrophobic carrier substances. Viscosity as one main influencing factor has been evaluated. Furthermore, the penetration behaviour in Beech (Fagus sylvatica) and Scots pine sapwood (Pinus sylvestris) after a vacuum/pressure impregnation has been analysed on macroscopic- and microscopic-level. During temperature increase, the investigated hydrophobic carrier substances showed differences in viscosity. Also differences in penetration depth after impregnation has been observed between Beech and Scots pine sapwood on macroscopic level. The microscopic analyses show the penetration pathways of the products for the tested wood species. The results will be used to optimize the impregnation processes with new oil based wood preservatives on pilot plant level as well as on industrial scale.
M Starck, A Gellerich, H Militz

Using plant oils as hydrophobic substances for wood protection
2010 - IRG/WP 10-30550
The increased interest to use oils as hydrophobic agents and the current debate about the further use of creosote emphasises the urgent need of better understanding of plant and other oils as wood protectors. The present study sheds light on the hydrophobic properties and distribution of various plant oils in the anatomical structure of Scots pine sapwood. Oil retentions from approximately 70 to 500 kg/m3 were achieved and tested. Analytical and microscopy techniques were used to reveal the distribution of oils in the wood cell wall and anatomical elements. Plant oils serve as mechanical barrier, diminishing the amount of free water in the wood structure but are not able to stop the progress of bound water. Modified plant oils showed significantly better hydrophobic properties after being associated with the main structural compounds. The anti swelling efficiency rises to 50-60%, thus being comparable with that of thermally modified wood. The new approach gives good prerequisites for modification of wood by means of plant oils.
D Panov, N Terziev, G Daniel

European Biocides Directive (98/8/EC): Programme for systematic examination of all active substances of biocidal products on the market on May 13, 2000 Article 16(2)
2001 - IRG/WP 01-50166-03
K Rasmussen, A B Payá Pérez

Termite trail-following substances in Houttuynia cordata
2001 - IRG/WP 01-10409
Termite trail-following active compounds in the plant, Houttuynia cordata Thunb., were studied by a combination of chemical analyses and bioassay using Coptotermes formosanus Shiraki as a test termite. We have found that termites were attracted to methanol extracts from H. cordata. The n-hexane(Hex) extracts, that showed a trail-following activity, were fractionated by a silica-gel column chromatography with Hex/ethyl acetate(EtOAc) successively increasing the polarity. The obtained 5%, 10%, 15% EtOAc/Hex fractions were found to be active. GC-MS analysis of the 5% EtOAc/Hex fraction showed a peak corresponding to 2-undecanone, which revealed weak activity.
W Ohmura, K Yamamoto, M Saegusa, T Ohira, A Kato

The biocides directive
1995 - IRG/WP 95-50040-25
G Wilson

Safety technique in wood preservation
1974 - IRG/WP 54
S N Gorshin, I G Krapivina, B I Telryatnikova

Developements in the EEC on the regulation of wood preservatives
1993 - IRG/WP 93-50016
There is a wide variation in the regulation of wood preservatives within the EEC, ranging from product by product authorization under persticides legislation to controls via standards, or simple compliance with basic requirements on classification packaging and labelling. During the past two years the commission of the European Communitiesn has worked on a proposal concerning the placing on the marketof biocidal procducts. This includes wood preservatives. The proposal is aimed at ensuring completion of the internal market in respect of these products and providing a high degree of protection for man and the environment. It provides for the creation at the Community level of a positiv list of active substances with authorization of individual products by member states. Provision is made for mutual authorization of products containing active substances of the positive list. Applications for authorization must be supported by data. Common principles for evaluation of applications will be developed and a programme for review of eyisting active substances will be established.
K Atkinson

The environmental chemistry of chromium: Science vs. U.S. law
1993 - IRG/WP 93-50014
The cooperation which existed among chromium chemical producers, industrial health laboratories, and governmet agencies was destroyed after 1970 by the advent of environmental activism and regulatory legislation. As prewar plants had been found to pose a serious cancer risk, this fact was the basis of EPA regulations, especially during the term of Joe Califano in HEW under Jimmy Carter. However, as health problems were identified by industry, the legal implications soon became apparent, and corporate scientists could release information only after clearance. This destroyed the free exchange of information necessary to the solution of scientific problems. Within the past few years, the closure of allied plants, the resolution of some superfund litigation, plus the release of records to the historical files at the Chemical Heritage Foundation, has clarified the scientific record. The following will be discussed: (1) The tendency of the present legal system to exaggerate risk. (2) Actual risks involved from inhalation, skin contact, and effluents. (3) the application of these principles to production, use and disposal of CCA and CCA-treated wood.
W H Hartford

Improvement of intrinsic properties of wood by chemical wood densification - Hydrophobic aspects and durability aspects
1999 - IRG/WP 99-40149
To improve the intrinsic properties of Scot pine wood ((1) hydrophobic surface and (2) durability), two ways of chemical modification have been tested. The first one is the chemical modification of hydroxyl groups by active substances like diisocyanate compounds with a copolymerization step. The second way is a densification by an impregnation of resins and a gamma polymerisation. This second way is described and discussed in this paper The measured parameters are (1) the hydrophobic properties of the surface based on permeability measurements and (2) the biological durability against wood decaying fungi and (3) the weathering behaviour. Significant results are presented and discussed to promote another way of wood preservation based on densification by resins.
G Labat, Q K Tran, I Le Bayon

Controlled envelope treatments of Pinus sapwood, achieved by modifications to impregnation process and carrier solvents
2003 - IRG/WP 03-40258
Specimens of slash pine or radiata pine were treated to a target retention of 0.02% m/m permethrin with conventional light organic solvent fluids or with oil-modified fluids (Tanalith® T). Best achievable envelopes from LOSP fluids were poorly controlled, penetrating not only the target outer 0-5 mm zone (mean 0.019%, RSD 28%), but also breaking through into the 5-10 mm zone (mean 0.013%, RSD 37%) and further into the >10 mm zone (mean 0.011%, RSD 52%). With the oil-modified fluids, the target 0-5 mm zone received a mean retention of 0.024% (RSD 30%), with 0.003% (RSD 44%) in the 5-10 mm zone and <0.002% the >10 mm zone. This tight control of toxicant distribution facilitates economical termite control.
M J Kennedy, P R S Cobham

Influence of hydrophobic agents on the leachability of boron
1995 - IRG/WP 95-30064
Besides its low mammalian toxicity and a broad range of activity towards both fungi and insects, boron shows a high diffusibility, encouraging it to treat wood species of low permeability. However, its difussibility is at the same time responsible for a high risk of leaching, known since long. Nevertheless quantitative data about this process are only rarely available. Therefore, the leaching of boron under different conditions and possible means of hydrophobising boron treated wood in order to reduce leaching were investigated by laboratory and field tests. For this purpose paraffin and a primer have been applied to protect the inner surface and alkyd-resin and a varnish as surface coat. The results demonstrate that boron diffuses even at moisture contents below 20%. Thus leaching can not be affected by hydrophobic agents placed on the inner surface of wood because diffusion still takes place within the cell-wall. Surface coatings have some protective effect but only during a distinct periode which is depending on the thickness of the coat. With time leaching increases with increasing moisture content underneath this coat. The best way to prevent leaching is the logistical protection by storing and using boron-treated wood exclusively under cover. Only for a short periode, for example during construction, a surface protection with waxes or resins will be effective.
A Peylo, H Willeitner

Preservative treatment of wood-based composites with a mixture formulation of IPBC-silafluofen using supercritical carbon dioxide as a carrier gas
2003 - IRG/WP 03-40251
Wood-based composites treated with a mixture formulation of a fungicide, 3-iodo-2-propynyl butylcarbamate (IPBC) and a termiticide, silafluofen using supercritical carbon dioxide (SC-CO2) as a carrier solvent were tested for their resistance to decay and termite attack in the laboratory. The treatment solution was prepared by mixing both biocides (IPBC 10 + silafluofen 1) with a co-solvent, ethanol to have an identical ratio of each constituent in the commercial formulation for superficial treatment of wood. SC-CO2 treatments were conducted at 35oC/7.85 MPa, 35oC/9.81 MPa and 55oC/11.77 MPa with a direct introduction of the biocidal solution into the treatment vessel where specimens (210 x 30 mm x thickness) of medium density fiberboard, hardwood plywood, softwood plywood, particleboard and oriented strand board were placed. Laboratory tests were conducted with the treated materials according to Japanese standard methods. Results of laboratory tests indicated that the current treatment conditions significantly enhanced the resistance of the treated wood-based composites against fungal and termite attacks. Comparison with the results obtained for wood-based composites treated with an individual biocide showed that treatment with a mixture would not cause any negative effect to the efficacy of each biocide, although the amount of each constituent in a mixture formulation must be carefully decided to provide wood-based composites with a satisfactory performance against any biological degradation when SC-CO2 is used as a carrier solvent.
K Tsunoda, M Muin

A novel chemical barrier system, KORDON® TMB, for the protection of buildings against subterranean termites using a synthetic matrix as carrier for the chemical
1998 - IRG/WP 98-10264
Kordon TMB is a new chemical barrier system for installation beneath concrete slab-on-ground constructions using a matrix other than soil as carrier for the termiticide. The product consists of a synthetic foraminous web (blanket) carrying the synthetic pyrethroid deltamethrin. The blanket is laminated on the upper side to a standard 0.2mm thick moisture vapour membrane of low density polyethylene (LDPE) and on the other side to a sheet of black 0.05mm UV-stabilised LDPE. Installation of the barrier follows existing building practice of setting down and sealing the vapour barrier, as required, during site preparation for building. Results of the evaluation of component materials and key features of the Kordon TMB system, which has been ongoing for the past eight years, are briefly discussed in this paper. Experiments simulated the use of treated webbing with or without LDPE under concrete slabs at sites near Griffith (New South Wales) in a semi-arid part of eastern Australia and near Darwin (Northern Territory) in the wet/dry tropics of northern Australia. In these trials timber has been protected from subterranean termite attack for more than seven to eight years at rates of 0.25 -2.50 g/m2 deltamethrin. In another series of studies, samples of wood protected by the webbing with LDPE were exposed to termites using a below-ground exposure method. To date, these trials have demonstrated successful protection of timber from termite attack for periods of six months to two years for rates from 0.01 - 1.00g/m2 deltamethrin. Laboratory studies have been conducted to simulate the Kordon TMB seals around service penetrations through the concrete slab. The first trial was conducted at incubation temperatures optimal to termite requirements, while a second series investigated the effectiveness of seals at lower temperatures more closely resembling conditions under a concrete slab. Based primarily on this work, Kordon TMB has been developed in Australia for approval by regulators.
M Lenz, P Morrow, S Runko

Quantification des émanations de substances dans l'air ambiant a partir des bois traités
1993 - IRG/WP 93-50001-27
Pesticides on wood for the purpose of its protection may evaporate. Eventual toxicity of such emanations justifies risk assessment procedures for indoor air in building. This document describes bench scale tests based on the technique of chambers developped by CTBA/BIOTEC to determine the amount of pesticides and associated substances released to the ambient air. Results obtained with various pesticides are reported. The part played by physico-chemical parameters including formulation is also described. Conclusions are that relevance of risk assessment procedures must pay atention to formulation, wood and in service conditions and that specific models might be necessary.
H Sageot, M Lamour

The influence of carrier fluid type on the efficacy of a wood preservative against cavity forming soft rot
2000 - IRG/WP 00-30244
Propiconazole was applied to Scots pine sapwood (Pinus sylvestris) and beech (Fagus sylvatica) using three different carrier systems selected on their varying ability to swell timber. The effects of microdistribution on the activity of cavity forming soft rot fungi were examined to determine the practical benefits of using swelling and non-swelling carriers with this active ingredient. Efficacy of the active ingredient delivered by different carriers against micro-fungi was assessed using EN (V) 807 (1998). After exposure, the relative mean mass loss of the timber samples was used to measure the extent of decay.
P A Hodges

The involvement of extracellular substances for the generation of hydroxyl radical during wood degradation by white-rot fungi
1997 - IRG/WP 97-10218
The activities of one-electron oxidation, hydroxyl radical generation, and phenol oxidase during the incubation of cultures of four white-rot fungi containing either glucose or wood were periodically measured. Further, their degradation activities against wood were examined during the course of cultivation. The generation of hydroxyl radical was correlated to the activity of wood degradation and it was not dependent upon the activity of oxidants such as phenol oxidase. The generation of hydroxyl radical was mostly due to the extracellular low molecular weight substances that catalyzed redox reaction between electron donors and O2 to produce H2O2 via O2 and to reduce H2O2 to HO·.The substances reduced Fe(III) to Fe(II) and strongly absorbed Fe(II).
H Tanaka, S Itakura, A Enoki

Enzyme immunoassay to detect Postia placenta in field tests: Comparison of plate ELISA with hydrophobic cloth and cotton dipstick
1991 - IRG/WP 2378
Standard indirect enzyme-linked immunosorbent assay in polystyrene 96-well plates was compared to hydrophobic polyester cloth and cotton dipstick for detection of wood-derived antigens from the brown-rot fungus Postia placenta. The ease of handling, larger surface area, and economics of the latter two adsorbents were surveyed for application as field tests for detection of early decay. At high antibody concentrations, the cloth ELISA (C-ELISA) exibited sensitivity comparable to the plate ELISA (P-ELISA), but at lower antibody concentrations signals diminished more rapidly for the C-ELISA. The dipstick assay lacked sensitivity even at high antibody concentrations, and suffered from inability to block a high nonspecific background. Nonporous polystyrene was judged superior to C-ELISA and cotton dipstick as the immobilizing phase for detecting antigen from Postia placenta by immunoassay, although at high antibody concentrations and increased incubation periods, C-ELISA matched the sensitivity of P-ELISA.
C A Clausen

Screening test methods with termites as first laboratory evaluation of new active substances for wood preservation
1995 - IRG/WP 95-10135
European test methods (EN) with termites have been compared with long-standing experience from screening test methods in the laboratory of Eberswalde. The results are discussed in terms on the possibility of using screening test methods as the first laboratory evaluation of new active substances in wood preservatives. The advantages and disadvantages of these methods are considered. Only a small amount of the active substance is necessary for a screening test and the results can be evaluated earlier, but screening tests also can provide additional information of value in the determination of preservative potential. The relationships between the determination of toxic properties for new biocides by screening test methods and the definition of the toxic value by standard laboratory methods are shown.
W Unger

Practical considerations of the Formosan subterranean termite in Louisiana: A 50-year-old problem
2000 - IRG/WP 00-10330
In an eleven-year censusing (1989 through 1999) in the French Quarter of New Orleans and surrounding areas, Coptotermes formosanus alate numbers were found to be increasing dramatically in all years but one. Moreover, in parks and neighborhoods in New Orleans and Lake Charles, LA, as well as in Sam Houston Jones State Park near Lake Charles surveyed in 1998, alarmingly high numbers of this exotic pest were observed infesting live trees. Termite baits and non-repellent termiticides have shown the most promise as practical weapons to combat the unprecedented termite problem in Louisiana. As a result of Federal and Louisiana State Government funding, termite treatments that offer population reduction are being intensively researched, improved upon and rapidly employed in large scale field tests in Louisiana. Over $20,000,000 dollars has been appropriated from 1998 to 2000, to develop new and employ existing tools to fight the Formosan subterranean termite. Fifteen public schools in Orleans, Jefferson and St. Bernard Parishes are being used in a study to evaluate the ability of two bait systems and one non-repellent termiticide to reduce termite populations. In an attempt to reduce the high labor costs associated with bait systems, a signaling device was invented by the author and J. K Paxson that indicates when termites are present in a bait. Application technology using non-repellent termiticides was also developed for treatment of infested trees. In 2000, 300,000 trees will be drilled by pest control operators and injection of a foam solution of fipronil or imidacloprid will be attempted. The Louisiana Formosan Termite Task Force Technical Committee is considering ways to implement a wood treatment program for new home construction, and quarantine measures to stop the movement of termites to new areas via the transport of infested wood, especially railroad ties and telephone poles.
G Henderson

Efficacy of Avermectin B1 dust and bait formulations in new simulated and accelerated field tests
1985 - IRG/WP 1257
Avermectin B1 on a silica carrier dust was used in dust and bait formulations whose efficacy against Reticulitermes flavipes was assessed in new simulated and accelerated field tests. A 0.5 mg avermectin/mg dust and a bait with 50 ppm avermectin in paper pulp sandwiched between pieces of corrugated boxboard caused nearly complete mortality in bioassays and suppression of foraging in field tests. These results indicate that the formulations can be developed into control effective gallery injection and/or bait treatments.
G R Esenther

Hydrophobic characteristics of pyrolysis oil
2008 - IRG/WP 08-30458
Hydrophobic behavior of pyrolysis oils obtained by pyrolysis of Scots pine wood (Pinus sylvestris L.) by using extruder type pyrolyzer at 450, 550 and 600 ºC was the objective of the study. Sapwood specimens (15×25×50 mm along the grain) were impregnated with the obtained pyrolysis oils by full- and empty cell treatment. The results indicated that wood impregnated with the studied pyrolysis oils has significantly lower water absorption values than that of the control group. Promising results were found about the anti swelling efficacy of the oils, being in the range of 60-90%. No significantly difference was found in the hydrophobic characteristic of wood samples treated by full- and empty cell process even though the oil uptake of samples treated with full cell process was significantly higher than that of the empty cell process.
A Temiz, M Hakki Alma, N Terziev

Emission Rates of Active Substances from Preserved Wood in Use Class 3
2008 - IRG/WP 08-50256
The evaluation of an active substance or a biocidal product under the Biocidal Products Directive (BPD) requires that an environmental risk assessment is carried out. The risk assessment for wood preservatives includes scenarios for preserved wood (e.g. cladding on a house), in which the predicted environmental concentration (PEC) in soil is calculated, using an emission rate for the active substance from the treated wood. The emission rate is critical to the environmental risk assessment of preserved wood and ultimately to the risk mitigation measures required for the preserved wood in storage and in service. This document reviews the published literature concerning the estimation of emission rates from preserved wood, covering laboratory leaching tests, such as EN84 and OECD Guideline tests, and emissions from board and panel tests in outdoor exposure. The results are compared with the results from a modified EN84 test which explains the ‘exponential’ profile of results in laboratory leach tests, and a ‘single board’ outdoor exposure test which shows a ‘sawtooth’ profile. The results are also compared with the emission values which have been used in the Biocidal Products Directive evaluation of active substances and published in the Evaluation Reports. Proposals are made for the use of a harmonized approach and realistic emission rates in the Product Authorisation phase of the BPD.
E F Baines

Hydrofluoroalkanes as carrier solvents for timber preservation
2009 - IRG/WP 09-40463
Hydrofluoroalkanes are a specific category of hydrofluorocarbon (HFC) commonly used in refrigeration applications. Some HFCs hold potential for use as carrier fluids for preservatives used to protect timber above ground. They do not share the most significant disadvantages of currently used carriers for these applications. At ‘conventional’ operating pressures, they are capable of rapid, full penetration of some timbers generally considered refractory, such as spruce and the heartwood of radiata pine. But they are comparatively expensive and, while they are not detrimental to the ozone layer, they would contribute significantly to the greenhouse effect if released. Impregnation process conditions can be optimised to maximise biocide solubility and impregnation speed and depth.
M J Kennedy, B Walker, C Erskine

The Effect of Water Repellent on Semi-Field Leaching of Active Substances from Metal Free Wood Preservative Formulation
2013 - IRG/WP 13-30615
The risk assessments for the use of wood preservatives proposed by the OECD and used under the Biocidal Products Directive (BPD) (98/8/EC) require the derivation of leaching rates for active substances. These rates are to be used as input data in to agreed exposure scenarios. A comparison of the leaching of active substances from wood treated with a metal free preservative formulation with and without water repellent is presented. The water repellent was selected to have good beading properties rather than conferring dimensional stability. The wood is exposed horizontally in a semi-field test based on the principles of NT Build 509. The volumes of leachates recovered after rain events are analysed to inform a discussion of the action of the water repellent. The leachate analysis data indicate that initially the leaching by natural rainfall is unaffected by the water repellent. However, after approximately 3 weeks (~ 45 mm rain) the leaching of active substances from the wood treated with water repellent is suppressed. After approximately 871mm of natural rainfall, active A shows 25% reduction in leaching and active B shows 24% reduction in leaching. The leaching of active substances from wood in service is an important consideration in environmental risk assessments. These results indicate that the environmental impact of wood preservative active substances can be reduced by the inclusion of water repellents in the formulation.
D G Cantrell

Borate Redistribution in Glulam in an Above Ground Field Test
2014 - IRG/WP 14-30652
Researchers have refocused on the use of boratesin the wood protection industry in the last two decades due to their broad spectrum effectiveness against fungi and insects, and favourable environmental characteristics. This study was designed to determine borate distribution in a limited number of samples from a large field test of composites protected by a combination of coating and borate treatment by two processes.The intended application of these products was exterior components of buildings with considerable protection by design, but the test method was designed to be a much more severe exposure. A variety of structural composites had been machined into ɣ-joint test samples, then borate-treated by two methods: a surface-applied penetrating process, and a dip treatment with borate/glycol plus insertion of copper/borate rods.After application of the coating the test samples had been installed in a long-term above-ground outdoor weathering trial at FPInnovations’ Maple Ridge, British Columbia test site. After seven years of exposure, selected glulam beams of black spruce, white spruce, and Douglas-fir samples were destructively sampled and analyzed for borate retention and penetration, with results compared to unexposed material.Results showed that borateshad migrated from the surface of exposed samples to inside the wood, as deep as 50 mm, and in many samples were present in concentrations that would be sufficient to prevent fungal decay.
P I Morris, A Temiz, J Ingram

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