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PubMed2006

Occupational exposure to inhalable wood dust in the member states of the European Union.

The aim of this study was to estimate occupational exposure to inhalable wood dust by country, industry, the level of exposure and type of wood dust in 25 member states of the European Union (EU-25) for the purposes of hazard control, exposure surveillance and assessment of health risks. National labour force statistics, a country questionnaire (in 15 member states, EU-15), a company survey (in Finland, France, Germany and Spain), exposure measurements (from Denmark, Finland, France, Germany, The Netherlands and the United Kingdom) and expert judgements were used to generate preliminary estimates of exposure to different types of wood dust. The estimates were generated according to industrial class (six wood industries, four other sectors) and level of exposure (five classes). These estimates were reviewed and finalized by national experts from 15 member states. Crude estimates were generated also for 10 new member states (EU-10). The basic data and final estimates were included in the WOODEX database. In 2000-2003, about 3.6 million workers (2.0% of the employed EU-25 population) were occupationally exposed to inhalable wood dust. Of those, construction employed 1.2 million exposed workers (33%), mostly construction carpenters. The numbers of exposed workers were 700,000 (20%) in the furniture industry, 300,000 (9%) in the manufacture of builders' carpentry, 200,000 (5%) in sawmilling, 150,000 (4%) in forestry and <100,000 in other wood industries. In addition, there were 700,000 exposed workers (20%) in miscellaneous industries employing carpenters, joiners and other woodworkers. The numbers of exposed workers varied by country ranging from <3,000 in Luxembourg and Malta to 700,000 in Germany. The highest exposure levels were estimated to occur in the construction sector and furniture industry. Due to limited exposure data there was considerable uncertainty in the estimates concerning construction woodworkers. About 560,000 workers (16% of the exposed) may be exposed to a level exceeding 5 mg m(-3). Mixed exposure to more than one species of wood and dust from wooden boards was very common, but reliable data on exposure to different species of wood could not be retrieved. This kind of assessment procedure integrating measurement data, company data, country-specific data and expert judgement could also serve as one model for the assessment of other occupational exposures.

Air Pollutants, Occupational↗
PubMed2002

Age- and position-related changes in hydraulic versus mechanical dysfunction of xylem: inferring the design criteria for Douglas-fir wood structure.

We do not know why trees exhibit changes in wood characteristics as a function of cambial age. In part, the answer may lie in the existence of a tradeoff between hydraulic properties and mechanical support. In conifers, longitudinal tracheids represent 92% of the cells comprising the wood and are involved in both water transport and mechanical support. We used three hydraulic parameters to estimate hydraulic safety factors at several vertical and radial locations in the trunk and branches: vulnerability to cavitation; variation in xylem water potential (psi); and xylem relative water content. The hydraulic safety factors for 12 and 88 percent loss of conductivity (S(H12) and S(H88), representing the hydraulic safety factors for the air entry point and full embolism point, respectively) were determined. We also estimated the mechanical safety factor for maximum tree height and for buckling. We estimated the dimensionless hydraulic and mechanical safety factors for six seedlings (4 years old), six saplings (10 years old) and six mature trees (> 110 years old) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Over the natural range of psi, S(H12) decreased linearly from treetop to a minimum of 0.95 at the tree base. Young and mature trees had S(H12) values 1.4 and 1.3 times higher, respectively, at their tips (juvenile wood) than at their bases (mature wood). Modeling analyses indicated that if trees were made entirely of mature wood, S(H12) at the stem base would be only 0.7. The mechanical safety factor was 1.2 times higher for the base of the tree than for the rest of the tree. The minimum mechanical safety factor-1.6 for the critical buckling height and 2.2 for the critical buckling load-occurred at the base of the live crown. Modeling analysis indicated that if trees were made only of mature wood, these values would increase to 1.7 and 2.3, respectively. Hydraulic safety factors had values that were less than half those for mechanical safety factors, suggesting that wood structure in Douglas-fir has evolved primarily as a result of selection for hydraulic safety rather than mechanical safety. The results suggest that forest managers must consider the role of juvenile wood in tree physiology to avoid producing plantations vulnerable to drought.

Oregon↗
PubMed2006

Simulation of effects of wood microstructure on water transport.

A tracheid-level model was used to quantify the effects of differences in wood microstructure between coastal and interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii and var. glauca) wood on larger scale properties like hydraulic conductivity. The model showed that tracheid length, the ease of flow through a bordered pit and effective tracheid diameter can all limit maximum hydraulic conductivity. Among the model parameters tested, increasing bordered pit conductivity and tracheid length resulted in the greatest increase in maximum conductivity in both the inland and coastal ecotypes. A sensitivity analysis of the uncertainty between parameters governing flow through the bordered pit and air-seeding potential showed that, although decreased pit flow resistance increased maximum hydraulic conductivity, increased cavitation led to lower conductivity over time. The benefits of increasing the number of bordered pits depended on the intensity of the meteorological driving function: in drier environmental conditions, wood with fewer pits was more conductive over time than wood with more pits. Switching the bordered pit characteristics between coastal and interior wood indicated that the conductivity time course of coastal and interior wood was primarily governed by differences in the number of bordered pits and not differences in tracheid dimensions. The rate at which tracheids refilled had little effect on the conductivity time course of either coastal or interior wood during the first two summers when the wood was highly saturated, but had a marked influence in subsequent years once the cavitation profile stabilized. Our work highlights the need for more empirical work on bordered pits to determine whether variation in their number and properties is related to changing environmental conditions. In addition, a detailed simulation model of a bordered pit is needed to understand how variation in pit properties affects the relationship between ease of flow through a bordered pit and its potential for facilitating air-seeding.

Biological Transport↗
PubMed1990

Magnetic resonance imaging and computed tomographic scanning of fresh (green) wood foreign bodies in dog orbits.

Wooden foreign bodies in the orbit can extend into the intracranial cavity without diagnostic clues from the small eyelid entrance wound, from neurologic examination, and from imaging studies such as ultrasound, plain x-rays, or computed tomography (CT) scans. In cadaver magnetic resonance imaging (MRI) studies, dry wood in the orbit can be seen as a negative or hypointense image in contrast to orbital fat. We studied fresh, green wood in dogs to determine the reliability of CT and MRI scans to image hydrated wood. Wood was placed into each orbit of two dogs. After 24 h the wood was removed from one orbit, but not the other. The dogs were then scanned with CT and MRI. Radiologists were asked to determine if any wood had been left in either or both orbits. The fresh wooden foreign bodies could not be detected despite an intensive effort. MRI does not appear to reliably demonstrate fresh wood in the orbit. MRI can show dry wooden foreign bodies that have not become hydrated, but has not yet been reliable in the clinical situation to rule out the presence of wood in the orbit.

Animals↗
PubMed2006

Decaying wood is a sodium source for mountain gorillas.

Like several other non-human primates, mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda consume decaying wood, an interesting but puzzling behaviour. This wood has little obvious nutritional value; it is low in protein and sugar, and high in lignin compared to other foods. We collected pieces of wood eaten and avoided by gorillas, and other foods consumed by gorillas, and measured their sodium content. Wood was substantially higher in sodium than other dietary items, and wood pieces from stumps eaten contained more sodium than those that were avoided. Wood represented only 3.9% of the wet weight food intake of gorillas, but contributed over 95% of dietary sodium, leading us to conclude that decaying wood is an important sodium source for Bwindi gorillas. Because sodium has been leached from the weathered soils characteristic of the subhumid and humid tropics, and because terrestrial plants generally do not require sodium, tropical herbivores, including gorillas, often encounter problems locating the sodium essential for their well-being. Decaying wood is an unexpected sodium source.

Animal Nutritional Physiological Phenomena↗
PubMed2005

Identification of an obeche (Triplochiton scleroxylon) wood allergen as a class I chitinase.

BACKGROUND: Wood dust is known to cause allergic occupational asthma and obeche (Triplochiton scleroxylon) is a prominent exponent in this field. However, the knowledge about wood allergens is still limited. The aim of this study was to identify and characterize obeche wood allergens. METHODS: Obeche extracts were prepared from freshly ground in comparison to 7 years stored wood dust and investigated by Sodium dodecyl sulfate-polyacrylamid gel electrophoresis, enzyme-linked allergosorbent test and immunoglobulin (Ig)E-immunoblot. Allergens were detected by specific IgE of seven obeche allergic patients' sera and protein analysis was performed by mass spectrometry. Cross-reactivity was demonstrated by ImmunoCAP-inhibition with sera of seven obeche and four latex-allergic patients. RESULTS: Obeche extracts showed different protein pattern and IgE-binding capacities depend on the age of the wood dust. A 38 kDa protein was identified as major obeche wood allergen, detected by six of seven (85%) obeche allergic patients' sera and was entitled as Trip s 1. Trip s 1 is homologous to plant class I chitinases and exhibited enzyme activity demonstrated by chitinolysis. Co-recognition or cross-reactivity of Trip s 1 according to structural similarity was seen in sera of latex allergic patients. IgE inhibition studies with obeche as solid phase and Trip s 1 and latex hevein as inhibitor demonstrated that Trip s 1 was a more effective inhibitor in obeche as well as in latex allergic patients' sera. CONCLUSIONS: Trip s 1 is a new obeche wood allergen of the plant class I chitinase family. This finding may explain the dominant role of obeche in sensitization against wood dust.

Adult↗
PubMed2006

Activities of chitinolytic enzymes during primary and secondary colonization of wood by basidiomycetous fungi.

The nitrogen (N) content of wood is usually suboptimal for fungal colonization. During decomposition of wood, an increasing fraction of the N becomes incorporated into fungal mycelium. Between 5 and 50% of the N in wood-degrading mycelium may be incorporated into chitin. Chitinolytic enzymes render this N available for re-utilization. Here, the activities of chitinolytic enzymes produced by wood-rotting fungi during degradation of spruce (Picea abies) wood were quantified in situ using fluorogenic 4-methylumbelliferyl substrates. A new method was developed that enables spatial quantification of enzyme activities on solid surfaces. All of the three tested fungi produced endochitinases, chitobiosidases and N-acetylhexosaminidases during colonization of wood. N-acetylhexosaminidase activity, and in some cases also chitobiosidase and endochitinase activities, were higher during secondary overgrowth of another fungus than during primary colonization of noncolonized wood. The results suggest that wood-degrading fungi degrade their own cell walls as well as the hyphae of earlier colonizers. Recycling of cell wall material within single mycelia and between fungal individuals during succession may lead to retention of N within woody debris.

Basidiomycota↗
PubMed2006

Wood-inhabiting fungal communities in woody debris of Norway spruce (Picea abies (L.) Karst.), as reflected by sporocarps, mycelial isolations and T-RFLP identification.

Wood-inhabiting fungi play a key role in forest ecosystems and constitute an essential part of forest biodiversity. We therefore examined the composition and abundance of wood-inhabiting fungi by three methods: sporocarp counts, mycelial culturing and direct amplification of internal transcribed spacer terminal restriction fragment length polymorphism from wood combined with sequencing of reference rDNA. Seven-year-old slash piles left after a thinning were analyzed in a 50-year-old Norway spruce plantation. Fifty-eight fungal species were detected from the piled branches and treetops. More species were revealed by sporocarp counts and cultured mycelia than by direct amplification from wood. In principle, sporocarp monitoring may reveal all fruiting taxa, but it poorly reflects their relative abundance in the wood. In contrast, terminal restriction fragment length polymorphism will record the most frequent fungal taxa in the wood, but it may overlook uncommon taxa. Culturing mycelia from wood gives a bias towards species favoured by the cultural medium. The results demonstrate the advantage and the limitations of these methods to be considered in analyses of fungal communities in wood.

Ascomycota↗
PubMed2004

Effects of furniture polish on release of cat allergen-laden dust from wood surfaces.

UNLABELLED: The purpose of this study was to evaluate the effects of furniture polish (FP) on the release of cat allergen (Fel d 1)-laden dust from wood surfaces and decay of Fel d 1 in dust over time. About 2 g of sieved (150 microm screen) allergen-laden dust was introduced as an aerosol into an experimental chamber by a Pitt-3 generator and allowed to settle onto two finished wood surfaces pre-treated with either distilled water (DW) or FP. After 24 h, each surface was vacuumed into separate plastic cassettes loaded with 37 mm diameter, 0.4 microm pore, polycarbonate filters. The recovered dust was weighed, extracted in phosphate-buffered saline, and assayed for Fel d 1 content using a two-site monoclonal antibody ELISA. After vacuuming, the remaining dust on the wood surfaces was wiped up with a water-moistened swab. The dusts were extracted from the swabs and assayed by ELISA for Fel d 1. More Fel d 1 was recovered by vacuuming from DW-pre-treated surfaces than from FP pre-treated surfaces (100% vs. 69 +/- 66%). On the contrary, more residual Fel d 1 (>99.9%) on the vacuumed surfaces was recovered from FP than from DW pre-treated surfaces by wet swabs. The concentration of Fel d 1 in dust did not change significantly at room temperature over 80 days. In conclusion, FP on wood surfaces makes dust stick to the surface, which likely reduces the release of allergen-laden dust from the wood surface. PRACTICAL IMPLICATIONS: Re-aerosolization of cat allergen-laden dusts from wood surfaces (e.g. wood floor or furniture) significantly increases the concentration of airborne cat allergens. Our study indicates that exposure to airborne cat allergens might be reduced by surface treatment with commercially available FP because cat allergen-laden dusts stuck more tightly to the wood surface treated with FP.

Air Pollution, Indoor↗
PubMed2002

Production of new unsaturated lipids during wood decay by ligninolytic basidiomycetes.

Lipids were analyzed by gas chromatography-mass spectrometry for a 7-week in vitro decay of eucalypt wood by four ligninolytic basidiomycetes. The sound wood contained up to 75 mg of lipophilic compounds per 100 g of wood. Hydrolysis of sterol esters, which represented 38% of total wood lipids, occurred during the fungal decay. The initial increase of linoleic and other free unsaturated fatty acids paralleled the decrease of sterol esters. Moreover, new lipid compounds were found at advanced stages of wood decay that were identified from their mass spectra as unsaturated dicarboxylic acids consisting of a long aliphatic chain attached to the C-3 position of itaconic acid. These dicarboxylic acids were especially abundant in the wood treated with Ceriporiopsis subvermispora (up to 24 mg per 100 g of wood) but also were produced by Phlebia radiata, Pleurotus pulmonarius, and Bjerkandera adusta. We hypothesize that three main alkylitaconic acids (tetradecylitaconic, cis-7-hexadecenylitaconic, and hexadecylitaconic acids) are synthesized by fungi in condensation reactions involving palmitic, oleic, and stearic acids. We suggest that both wood unsaturated fatty acids (present in free form or released from esters during natural decay) and unsaturated metabolites synthesized by fungi could serve as a source for peroxidizable lipids in lignin degradation by white rot basidiomycetes.

Basidiomycota↗
PubMed2005

Isolation of wood-inhabiting fungi from Canadian hardwood logs.

Wood-inhabiting fungi include many molds, wood-staining fungi, and decay fungi. Most of these fungal species can result in economic losses to wood users. Studies on molds, staining fungi, and decay fungi are necessary to be able to control their growth on wood and wood products. In this study, wood-inhabiting fungi were isolated from logs of 3 major Canadian hardwood species: sugar maple, white birch, and yellow birch. Two media were used for isolation. From these 3 wood species, a total of 1198 fungal cultures were obtained from summer- and winter-harvested logs in dry storage and under water sprinkling. The results showed that most fungal species were not host specific and affected all of the wood species tested. Frequently isolated molds were Alternaria alternata, Trichoderma species, and Mucor/Rhizopus (Zygomycota) species, frequently isolated staining fungi were Ophiostoma piceae and Ophiostoma piliferum, a frequently isolated bark saprophyte was Nectria cinnabarina, and frequently isolated decay fungi were taxa of the phylum Basidiomycota. More fungal species were isolated from summer-harvested logs than from winter-harvested logs. Fewer fungal cultures, especially decay fungi, were isolated from logs in early storage than from logs in late storage.

Acer↗
PubMed2003

Near-infrared spectroscopic monitoring of the diffusion process of deuterium-labeled molecules in wood. Part II: hardwood.

Fourier transform near-infrared (FT-NIR) transmission spectroscopy was applied to monitor the diffusion process of deuterium-labeled molecules in hardwood (Beech). The results are compared with previous data obtained on softwood (Sitka spruce) in order to consistently understand the state of order in cellulose of wood. The saturation accessibility and diffusion rate varied characteristically with the OH groups in different states of order in the wood substance, the diffusants, and the wood species, respectively. The variation of saturation accessibility should be associated with the fundamental difference of the fine structure such as the microfibrils in the wood substance. The effect of the anatomical cellular structure on the accessibility was reflected in the variation of the diffusion rate with the wood species. The size effect of the diffusants also played an important role for the diffusion process in wood. Since the volumetric percentage of wood fibers and wood rays is relatively similar, the dichroic effects due to the anisotropy of the cellulose chains were apparently diminished. Finally, we proposed a new interpretation of the fine structure of the microfibrils in the cell wall by comparing a series of results from hardwood and softwood. Each elementary fibril in the hardwood has a more homogeneous arrangement in the microfibrils compared to that in the softwood.

1-Butanol↗
PubMed2005

Use of treated woods in roof assembly.

On February 12, 2002, the US Environmental Protection Agency (EPA) announced a voluntary decision by industry to move consumer use of treated lumber products away from a variety of pressure-treated wood that contains Arsenate (As) by December 31, 2003, in favor of new alternative wood preservatives. It is the purpose of this report to outline legislative efforts to ban the use of chromated copper arsenate (CCA)-treated wood for residential roofing in the State of Oregon. At the time that the legislation was introduced, it was coincidental that the National Roofing Contractors Association (NRCA) recommended that CCA-treated wood should not be used in residential roofing. A summary of the report is included in this review. Finally, we discuss some of the potentially harmful environmental hazards of wood preservatives on the environment. In addition to the toxicity of pressure-treated wood on our environment, we point out that wood as well as pressure-treated wood assemblies are highly flammable. Consequently, we recommend the use of residential roofing systems that have Class A fire protection for the homeowner. Because residential roof fires remain a life-threatening danger to residential homeowners in the United States, we describe a national fire prevention program for reducing residential roof fires by use of an Underwriters Laboratories Inc. (UL) and National Fire Protection Association Class A fire-rated roof system.

Arsenates↗
PubMedDate not supplied

Biological effects of wood ash application to forest and aquatic ecosystems.

The present review aims to summarize current knowledge in the topic of wood ash application to boreal forest and aquatic ecosystems, and the different effects derived from these actions. Much research has been conducted regarding the effects of wood ash application on forest growth. Present studies show that, generally speaking, forest growth can be increased on wood ash-ameliorated peatland rich in nitrogen. On mineral soils, however, no change or even decreased growth have been reported. The effects on ground vegetation are not very clear, as well as the effects on fungi, soil microbes, and soil-decomposing animals. The discrepancies between different studies are for the most part explained by abiotic factors such as variation in fertility among sites, different degrees of stabilization, and wood ash dosage used, and different time scales among different studies. The lack of knowledge in the field of aquatic ecosystems and their response to ash application is an important issue for future research. The few studies conducted have mainly considered changes in water chemistry. The biotoxic effects of ash application can roughly be divided into two categories: primary and secondary. Among the primary effects is toxicity deriving from compounds in the wood ash and cadmium is probably the worst among these. The secondary effects of wood ash are generally due to its alkaline capacity and a release of ions into the soil and soil water, and finally, watercourses and lakes. Given current knowledge, we would recommend site- and wood ash-specific application practices, rather than broad and general guidelines for wood ash application to forests.

Animals↗
PubMed2002

[A case of occupational asthma caused by Ayous wood (Triplochiton scleroxylon)].

A 58-year-old man, a carpenter, had been suffering from cough, rhinorrhea, wheezing, dyspnea and ocular itching a few minutes after each exposure to the sawdust of "Ayous" wood (Obeche, Triplochiton scleroxylon) since starting to work on this imported wood in 1998. Although his symptoms improved soon after exposure, he had a secondary response several hours later. He had no symptoms when working with any other woods. In January, 2001, he came to our hospital, and occupational asthma was suspected. Peak flow monitoring revealed immediate- and late-type responses when he was exposed to Ayous wood dust. Non-specific bronchial hyperresponsiveness to acetylcholine was positive. An immediate skin test with Ayous wood extract was positive. In the RAST inhibition test, his serum revealed specific IgE antibody to Ayous extract. Bronchoprovocation with Ayous wood extract demonstrated immediate and later type responses (dual response). Occupational asthma caused by Ayous wood dust was confirmed. This is the first case report of occupational asthma caused by Ayous wood in Japan.

Asthma↗
PubMed2004

[Ecological function of wood-inhabiting fungi in forest ecosystem].

Wood-inhabiting fungi are one of the most important parts of forest ecosystem, and play an important role in degrading the wood in forest ecosystem. The major species of these fungi include the groups of Aphyllophorales (Basidiomycota), Discomycetes (Ascomycota) and some imperfect fungi. They have the ability to degrade cellulose, hemicelluloses and lignin of wood. Three type of wood decaying have been found, i.e., white rot, brown rot and soft rot. Many other organisms of forest ecosystem have symbiosis relationship with wood-decaying fungi. Wood-inhabiting fungi could offer the nutrition for many insects and birds, and spores of many wood-rotting species are spread by some insects. The high biodiversity of wood-decaying fungi is one of the important factors for the health of forest ecosystem.

Ascomycota↗
PubMed1990

Contact urticaria caused by Obeche wood (Triplochiton scleroxylon). Report of eight patients.

A variety of plant substances may induce contact urticaria and the list of substances responsible for such reactions is increasing. We report eight patients suffering from occupational asthma caused by Obeche wood sawdust. These patients also presented with urticaria when they worked with this wood. Studies revealed immediate positive skin test reactivity to Obeche wood extracts in all patients. The presence of specific IgE antibodies against Obeche wood could also be demonstrated by a reverse ELISA method. Finally, skin provocation tests (rubbing test) on the eight patients evoked a positive reaction within 20 minutes. These findings strongly suggest an IgE-mediated immunologic mechanism as responsible for the patients' urticaria. Obeche wood should be considered a health hazard capable of causing both bronchial asthma and contact urticaria. At the present time, this timber constitutes the most frequently commercially exported African wood. Many individuals, including carpenters and hobbyists, may come into contact with this wood due to the common use of Obeche wood in the "Do it yourself" type of shops.

Adult↗
PubMed1985

Nasal hypersensitivity in wood furniture workers.

Occupational nasal allergies were studied in six wood furniture factories. The concentration of moulds, wood dust and endotoxins was registered and occasionally high values were found. Paecilomyces spec. was the most common mould. A special questionnaire showed that 16% (42/268) of the wood workers with a mean exposure time of 12 years had a history compatible with hypersensitivity in the upper airways associated to their work. Rhinomanometric investigations showed mucosal congestion in the workers with nasal discomfort and nasal clearance was pathologically slow in 54%. Histological studies revealed a high incidence of unciliated and metaplastic nasal epithelium. Skin prick tests and provocation tests with standard allergens and allergens prepared from the moulds and the wood dust in the environment showed that the wood furniture workers had an incidence of allergy to moulds in 3% and to wood dust in 2%. Most of the workers sensitive to moulds and/or woods were also skin prick sensitive to other allergens. No statistical difference concerning the presence of precipitating antibodies against mould and wood antigens could be registered between workers with discomfort and workers without symptoms.

Air Microbiology↗