SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Two cases of occupational allergic contact dermatitis in plywood mill workers are presented. Although both patients thought they were allergic to sawdust, they were in fact allergic to a phenol-formaldehyde resin used to bond the plywood sheets together. Both patients only developed their dermatitis when they came into contact with uncured glue.
The long-term viability of a forest industry in the Amazon region of Brazil depends on the maintenance of adequate timber volume and growth in healthy forests. Using extensive high-resolution satellite analyses, we studied the forest damage caused by recent logging operations and the likelihood that logged forests would be cleared within 4 years after timber harvest. Across 2,030,637 km2 of the Brazilian Amazon from 1999 to 2004, at least 76% of all harvest practices resulted in high levels of canopy damage sufficient to leave forests susceptible to drought and fire. We found that 16+/-1% of selectively logged areas were deforested within 1 year of logging, with a subsequent annual deforestation rate of 5.4% for 4 years after timber harvests. Nearly all logging occurred within 25 km of main roads, and within that area, the probability of deforestation for a logged forest was up to four times greater than for unlogged forests. In combination, our results show that logging in the Brazilian Amazon is dominated by highly damaging operations, often followed rapidly by deforestation decades before forests can recover sufficiently to produce timber for a second harvest. Under the management regimes in effect at the time of our study in the Brazilian Amazon, selective logging would not be sustained.
Explore the source record for details and available documents.
Governing natural resources sustainably is a continuing struggle. Major debates occur over what types of policy "interventions" best protect forests, with choices of property and land tenure systems being central issues. Herein, we provide an overview of findings from a long-term interdisciplinary, multiscale, international research program that analyzes the institutional factors affecting forests managed under a variety of tenure arrangements. This program analyzes satellite images, conducts social-ecological measurements on the ground, and tests the impact of structural variables on human decisions in experimental laboratories. Satellite images track the landscape dimensions of forest-cover change within different management regimes over time. On-the-ground social-ecological studies examine relationships between forest conditions and types of institutions. Behavioral studies under controlled laboratory conditions enhance our understanding of explicit changes in structure that affect relevant human decisions. Evidence from all three research methods challenges the presumption that a single governance arrangement will control overharvesting in all settings. When users are genuinely engaged in decisions regarding rules affecting their use, the likelihood of them following the rules and monitoring others is much greater than when an authority simply imposes rules. Our results support a frontier of research on the most effective institutional and tenure arrangements for protecting forests. They move the debate beyond the boundaries of protected areas into larger landscapes where government, community, and comanaged protected areas are embedded and help us understand when and why deforestation and regrowth occur in specific regions within these larger landscapes.
Amid widespread reports of deforestation, some nations have nevertheless experienced transitions from deforestation to reforestation. In a causal relationship, the Forest Identity relates the carbon sequestered in forests to the changing variables of national or regional forest area, growing stock density per area, biomass per growing stock volume, and carbon concentration in the biomass. It quantifies the sources of change of a nation's forests. The Identity also logically relates the quantitative impact on forest expanse of shifting timber harvest to regions and plantations where density grows faster. Among 50 nations with extensive forests reported in the Food and Agriculture Organization's comprehensive Global Forest Resources Assessment 2005, no nation where annual per capita gross domestic product exceeded 4,600 dollars had a negative rate of growing stock change. Using the Forest Identity and national data from the Assessment report, a single synoptic chart arrays the 50 nations with coordinates of the rates of change of basic variables, reveals both clusters of nations and outliers, and suggests trends in returning forests and their attributes. The Forest Identity also could serve as a tool for setting forest goals and illuminating how national policies accelerate or retard the forest transitions that are diffusing among nations.
Explore the source record for details and available documents.
Sustainability requires living within the regenerative capacity of the biosphere. In an attempt to measure the extent to which humanity satisfies this requirement, we use existing data to translate human demand on the environment into the area required for the production of food and other goods, together with the absorption of wastes. Our accounts indicate that human demand may well have exceeded the biosphere's regenerative capacity since the 1980s. According to this preliminary and exploratory assessment, humanity's load corresponded to 70% of the capacity of the global biosphere in 1961, and grew to 120% in 1999.
Air contamination in sawmills can cause respiratory health problems. The authors measured respirable dust, bacteria, endotoxins, and molds collected from 17 sawmills in eastern Canada. A total of 1,205 sawmill workers answered a respiratory-health questionnaire, and they all participated in lung-function measurements, skin-prick tests, and venous blood sampling for specific immunoglobulins against molds found in the sawmills. Workers had normal lung functions, and most respiratory symptoms could be explained by smoking histories. Workers in pine sawmills had a greater prevalence of positive skin-prick test to pine than did workers in sawmills where other woods were used. High levels of specific antibodies were seen in some workers. The presence of a positive skin-prick test and/or specific antibodies had no impact on lung function(s). These Quebec sawmill workers did not experience significant respiratory illnesses; however, some of these workers may be at a higher risk of developing asthma and hypersensitivity pneumonitis than nonworkers.
The influence of machine function (tree felling and processing, and machine movement over the terrain) on operator exposure to whole-body vibration in a cut-to-length (CTL) timber harvester was evaluated. Vibrations were measured on the seat and the cabin chassis in three orthogonal (x, y, z) axes for the tree felling and processing, and during motion on a test track. It was found that the level of vibration transmitted to the operator during felling and processing was mainly affected by the tree size (diameter). For tree diameter at breast height (dbh) range of 0.25-0.35 m that was investigated, the vertical (z-axis) vibration component during processing increased by up to 300%, and increased by 50% during felling. However, the associated vibration levels were not sufficient to pose any serious health risks to the operator for an exposure limit of 8 h. Vibration at the operator seat and cabin chassis was predominant in the lateral (y-axis) and vertical (z-axis) respectively, during vehicle motion over the standard test track. Vibration peaks of approximately 0.20 and 0.17 ms(-2) occurred at 5 and 3.2 Hz respectively.
Physical workload, output of cut wood, and perceived exertion were studied among 15 younger (mean age 29 years) and 16 older (mean age 59 years) lumberjacks, using a chainsaw and paid on a piece-rate basis. Oxygen consumption was measured with portable equipment, while heart rate was measured telemetrically. The oxygen consumption for all working phases was 1.8 +/- 0.2 l/min (means +/- SD) (younger) and 1.5 +/- 0.2 l/min (older), which corresponded to 49 +/- 4% and 53 +/- 7% of maximal oxygen consumption estimated in ergometer bicycle exercise test. A negative relationship was found between relative oxygen consumption at work and maximal oxygen consumption (ml/kg/min). Mean heart rates for all working phases were 138 +/- 10 beats/min (younger) and 126 +/- 17 (older). The heart rate differed between the working phases, and was significantly higher for both groups during bunching than during the other operations. The output of cut wood did not differ significantly between the groups. Slight but significantly relationships were found between output of cut wood and maximal oxygen consumption (ml/kg/min) and oxygen consumption (ml/kg/min) during work. Rating of perceived exertion (RPE) and simultaneous heart rate recordings during cycle tests and field studies showed significant correlations between heart rate and RPE values during cycling in both groups. RPE values and heart rate in the field showed a slight correlation (younger) and not at all (older).
The vibration from chain saws can cause vibration-induced white finger disease (VWFD). Measurements of vibration levels on the front and rear handles of different chain saw-types, and on the operator's middle finger were collected at three logging camps on Vancouver Island. Factors effecting the vibration levels on the finger and handles were investigated. The acceleration at the firing frequency was found to be the dominant factor effecting handle and finger vibration. Other factors which were investigated were: grip force; the presence of handle covers; and chain sharpening procedure. Weighted acceleration levels are calculated and this information is used to assess the latency period for fallers to develop VWF disease.
The implement movement in today's mobile, heavy machinery does not correspond in a one-to-one proportion with hand control movement. This lack of correspondence places high perceptual and psychomotor demands on the operator. The objective of this study was to evaluate the human factors of two different machine control systems on a log loader in a controlled field setting. The traditional joint control system was compared with a co-ordinated control system. The two machines were tested on ten novice and six experienced operators. Operator performance was based on the time required to complete a task sequence, as well as reaction time. The results show that the novice operators performed significantly better in co-ordinated mode than they did in joint mode, whereas the experienced operators performed better in joint mode than they did in co-ordinated mode. Results indicate, however, that it would not take long for experienced operators to transfer their skills from joint control to co-ordinated control.
Cardiovascular and muscle strain were determined in 16 British Columbia reforestation workers during a period of tree planting (75 days). Serial data collected from each worker included pre- and post-work blood chemistry on the first day of the work shift; working heart rate (HR), a PWC170 fitness test, and a daily diary of an individual's work-rest schedule. Repeated blood samples from each planter were analysed for the elevated serum enzyme activities (ESEA) of creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate transaminase (AST), and for the blood haematology parameters (BH) of haematocrit (Hct), red blood cell count (RBC), and haemoglobin (Hgb). HR and BH were used as an index of cardiovascular strain and ESEA was used as an index for musculoskeletal strain. A group mean working heart rate of 116.5 +/- 9 b.min-1 (range 100.0-139.1) was sustained throughout the period of an 8.0 hour day representing 39.2% of the delta Heart Rate ratio (ratio of elevated working Hr above resting to maximum HR). Grouped data were analysed by sample day for a subset of planters (n = 10) participating in six sample dates during the first 32 days of planting. Pre- and post-work ESEA were significantly higher throughout the entire planting period when compared with a pre-season resting control group (n = 9, p < or = 0.01). The post-work rise in CK and AST from pre-work values decreased during successive weeks of work as some adaptation to the work rate occurred. LDH continued to rise and was significantly elevated on day 32 compared with day 1. No significance was found in the BH variables between sample dates, yet a decreasing trend was observed. However, pooled data from all subjects for all sample dates showed a highly significant difference (p < or = 0.01) between pre- and post-work samples for both ESEA and BH. ESEA increased and BH decreased. These data present evidence that the work rate and rest time of a tree planter are not well ordered within the daily and seasonal working routine, and may compromise worker well-being in the silviculture industry.
Tree planters in British Columbia have reported symptoms that are congruent with musculoskeletal stress and organophosphate or carbamate pesticide intoxication. The purpose of this research was to determine the existence of any physiological or biochemical correlate supporting the existence of these potential hazards in tree planting. Worker's health complaints were assessed from regularly distributed questionnaires. Blood samples were obtained from 14 male and three female Canadian subjects before and after tree planting work on 10 occasions throughout a tree planting season. The strenuous physical challenge of tree planting was confirmed by a significant elevation of serum enzyme activity (ESEA) at the beginning of the season, which did not return to a normal level during the remainder of the season. Significant (p < or = 0.05) inhibition of erythrocyte acetylcholinesterase activity (AChE) postwork was observed in 15.9% of individuals, and a significant group mean prework-postwork difference of AChE or plasma pseudocholinesterase (PChE) was observed on two days of testing, indicating a potential toxicological hazard from pesticide absorption. No correlation was found between the degree of ESEA or cholinesterase inhibition and the number of health complaints.
The highlights of a descriptive study on the ergonomics and occupational health and safety aspects of tree-planting in Québec are presented. The study was planned to consider the most representative geographical sites, planting technologies, and planting organizations. Semi-directed interviews were made with a mixed group of 48 male and female tree-planters and physiological measurements were made on four male planters. Tools and other equipment were also examined. An analysis of the work identified the main elements of the planting cycle, and the high cardiac rate in the working planters was related more to his manual transportation of seedlings and travel on rough paths than to planting per se. A tree-planter will typically travel 2.4 km carrying 16.8 kg of material and equipment in order to plant an average of 1245 seedlings daily. One out of two interviewed planters reported having a work-related accident or incident during his or her lifetime planting career. The body parts reported most frequently injured were the lower extremities (knee, foot, ankle), the skin, the eyes, and the wrist. Recommendations on the development of appropriate tools and footwear for tree-planters and for further research on repetitive strain injury induced by tree-planting have been made.
New Zealand loggers commonly use chainsaws weighing up to 10 kg. Chainsaw work is both physically arduous and potentially dangerous. A contributing factor to the high injury rate of loggers could be the high physiological and biomechanical load of chainsaw work. This study investigated the comparative cardiovascular strain imposed on 11 chainsaw operators when delimbing (cutting branches) with chainsaws of small, medium and large capacity under controlled conditions. Chainsaw operator cardiovascular strain increased with greater chainsaw weight and was associated with two chainsaw operator anthropometric dimensions (arm length and bent elbow height).
Two hundred and fifty-three farmers and forest workers and 249 clerks from south-west Sweden were recruited to a cross-sectional seroprevalence study to find out if individuals working outdoors are more prone to acquire Borrelia burgdorferi infection than indoor workers and to find undiagnosed cases of Lyme borreliosis. The participants answered a questionnaire and blood specimens were collected to estimate the prevalence of antibodies to B. burgdorferi in each group. Sera were analysed with an enzyme-linked immunoassay technique to determine IgG antibodies to B. burgdorferi flagellum. The prevalence of B. burgdorferi antibodies was 7.6% in the farmers and forest workers vs. 5.3% in the clerks (adjusted odds ratio [age, sex] = 1.2 [95% confidence interval = 0.5-2.8]). One case of Lyme borreliosis was diagnosed. The positive predictive value of the antibody test was estimated to be 3% in the studied populations. B. burgdorferi infection is of low endemicity in south-west Sweden and is probably not an occupational risk among outdoor workers. Undiagnosed cases of Lyme borreliosis are uncommon. The test used is not acceptable for screening purposes.
Paper is one of the basic needs of modern life. With the consumption of paper likely to grow to 320 million MT by the year 2001, the the worldwide pulp and paper industry is gradually realizing that there is a shortage of the traditional raw material of cellulosic fiber. Bagasse--a byproduct of the sugar industry, presents a potential source of fiber for the paper industry without further compromising the environmental concern. It is cheap, perennially replenishible, presently does not have an alternative economically attractive value added usage, and has adequate chemical and mechanical properties for paper making. However, for it to be available to the paper industry throughout the year, it needs to be stored and preserved for a period of 6 to 8 months. With inherent problems associated with bagasse morphology, intricacies reflected as a result of its physicochemical characteristics, army of microbial infestants, cost-effective quality expectations of the paper industry, and the ecofriendly approach demanded by the society/pollution control boards/environmentalists, there does not seem to be any viable alternative except to use biotechnology approaches for bagasse preservation. It envisages the preservation of maximally depithed bagasse in the piles/heaps, using one-time fine misting of a preservative formulation comprised of biodegradable and nondegradable chemicals inhibiting the microbial population at selected enzyme levels. Its efficacy is improved by open, dry, windy, and moderate sunlit sites for storage. The method is simple, sustainable, and superior to the prevalent methods that are cost, capital, and energy intensive, non-eco-friendly and have adverse cost:benefit ratios. The biotechnology approach has an inherent scope for further optimization, automation, and economization.