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PubMed1992

Herbicides and cancer.

Herbicides are a heterogeneous class of chemicals used in agriculture, forestry, and urban settings to kill weeds, shrubs, and broad-leaved trees. The role of herbicides in the etiology of cancer is controversial. Potential studies for review were identified through a MEDLINE search and from a check of references in related review articles. This review of the literature shows reasonable evidence suggesting that occupational exposure to phenoxy herbicides results in increased risk of developing non-Hodgkin's lymphoma. Several studies have noted large increases in risk of soft-tissue sarcomas with phenoxy herbicide exposure. In contrast, others have failed to observe increased risks, and evidence of an exposure-risk relationship is lacking. Although there have been too few appropriate studies for adequate assessment of risk of cancer at other sites, some findings have linked herbicide exposure with cancers of the colon, lung, nose, prostate, and ovary as well as to leukemia and multiple myeloma. Future studies must better identify and quantify the nature of herbicide exposures. In the interim, it seems only prudent to monitor and promote safety practices among persons occupationally exposed to phenoxy herbicides, particularly farmers and professional sprayers.

Animals↗
PubMed2006

Hyperspectral remote sensing of plant pigments.

The dynamics of pigment concentrations are diagnostic of a range of plant physiological properties and processes. This paper appraises the developing technologies and analytical methods for quantifying pigments non-destructively and repeatedly across a range of spatial scales using hyperspectral remote sensing. Progress in deriving predictive relationships between various characteristics and transforms of hyperspectral reflectance data are evaluated and the roles of leaf and canopy radiative transfer models are reviewed. Requirements are identified for more extensive intercomparisons of different approaches and for further work on the strategies for interpreting canopy scale data. The paper examines the prospects for extending research to the wider range of pigments in addition to chlorophyll, testing emerging methods of hyperspectral analysis and exploring the fusion of hyperspectral and LIDAR remote sensing. In spite of these opportunities for further development and the refinement of techniques, current evidence of an expanding range of applications in the ecophysiological, environmental, agricultural, and forestry sciences highlights the growing value of hyperspectral remote sensing of plant pigments.

Biosensing Techniques↗
PubMed2001

The calculation of accident risks in fitness for work assessments: diseases that can cause sudden incapacity.

Risk equations have been developed to assist in determining fitness for work of people with diseases that may cause rapid loss of control. The four equations calculate the frequency of fatal injury to the person with the disease, the frequency of fatal injury to colleagues in the workplace, and the cost of fatal injury and property damage to the employer. It is suggested that the additional risk of fatal injury to the person with the disease should not exceed the fatal injury rate in high-risk industries such as forestry, fishing and mining. It is also suggested that the additional risk of fatal injury to each colleague should be no more than one-tenth of the fatal injury rate due to motor vehicle accidents in the community. Two hypothetical case examples are given, demonstrating the use of the equations. The equations highlight the need to examine the risks associated with individuals, their specific jobs and their workplaces. They also highlight significant uncertainties in the determination of fitness, which perhaps have been underestimated in the past. Wherever possible, redundant defences should be utilized to prevent accidents in the event of sudden incapacity.

Accident Prevention↗
PubMed2002

An analysis of the causes of mortality among seafarers in the British merchant fleet (1986-1995) and recommendations for their reduction.

This study was designed to establish the manner and causes of all fatalities among seafarers who were serving in British merchant shipping between 1 January 1986 and 31 December 1995. Other main aims were to compare mortality rates with workers in other industries and with seafarers in other merchant fleets, and to discuss recommendations for the prevention of occupational mortality. This study was based upon official mortality files with a population of 253 919 seafarer-years at risk. There was a total of 252 fatalities in British merchant shipping during the study period. One hundred and seven of the 252 deaths were due to natural causes, of which 93 (87%) were caused by cardiovascular disease. The relative risk of mortality due to accidents at work (96 fatalities) was 23.9 times higher than for all workers in Great Britain during the same time period (95% confidence interval = 14.0-40.7). The risk of a fatal accident in merchant shipping was also much higher than in other British industrial sectors, such as agriculture, forestry and fishing (relative risk = 4.5), construction (5.5), and manufacturing (22.0). Seafaring was identified as a dangerous occupation compared with shore-based employment. Many of the fatal accidents at work were caused by hazardous working practices and were often preventable, as were the many off-duty accidents and drowning that were caused by seafarers falling into docks when encountering hazardous access to their ships from the shore. Seafarers are also at special risk from acute illnesses since they lack direct access to specialist medical care.

Accidents, Occupational↗
PubMed2002

The estimated workforce served by occupational physicians in the UK.

During the past decade, an occupational disease surveillance scheme has been created in the UK, based on systematic reporting of newly diagnosed cases by six groups of clinical consultants and by specialist occupational physicians. Labour Force Survey statistics have proved a reasonably satisfactory denominator for the former, but not for the occupational physicians, who provide services for only a selected subsection of the employed population. To remedy this deficiency, approximately 700 occupational physicians who were recorded as having been a reporter at some time were invited to provide their best estimate of the number of employees for whom they were responsible. After various exclusions--mainly physicians who were not, or were no longer, responsible for any defined workforce, and others who had not reported for at least 3 years--the number of active participants for whom data, by industry, occupation and sex, were obtained or estimated was 503. The resulting total number of employees served was estimated at 3.2 million, comprising 12% of the general working population. The proportion with access to an occupational physician varied enormously, from 43% in the health and social services to 1% in agriculture, forestry and fishing, and 6% in the rest of industry. Numbers estimated for each industrial sector were fairly reliable, but by occupation less so, especially in the health and social services.

Female↗
PubMed2000

Occupational lung cancer risk for men in Germany: results from a pooled case-control study.

Occupational exposures such as crystalline silica, diesel engine exhaust, polycyclic aromatic hydrocarbons, and man-made mineral fibers are strongly suspected to increase lung cancer risk. Two case-control studies in Germany conducted between 1988 and 1996 were pooled for a joint analysis. A total of 3,498 male cases and 3,541 male population controls, frequency matched for age and region, were included in the study. The lifelong history of all jobs and industries was coded and occupational exposures were evaluated by expert rating. Odds ratios, crude and adjusted for smoking and asbestos exposure, were calculated by conditional logistic regression. Job-related evaluation showed a statistically significant increased odds ratio adjusted for smoking among farmers; forestry workers, fishermen, and livestock workers; miners and quarrymen; chemical processors; cabinet makers and related wood workers; metal producers and processors; bricklayers and carpenters; road construction workers, pipelayers and well diggers; plasterers, insulators, and upholsterers; painters and lacquerers; stationary engine and heavy equipment operators; transport workers and freight handlers; and service workers. With regard to specific occupational exposures, elevated odds ratios (OR) (95% confidence intervals (CI)) for lung cancer risk adjusted for smoking and asbestos exposure were observed for man-made mineral fibers (OR = 1.48, 95% CI 1.17, 1.88); crystalline silica (OR = 1.41, 95% CI 1.22, 1.62); diesel engine exhaust (OR = 1.43, 95% CI 1.23, 1.67); and polycyclic aromatic hydrocarbons (OR = 1.53, 95% CI 1.14, 2.04). The risk of asbestos exposure, adjusted for smoking was also increased (OR = 1.41, 95% CI 1.24, 1.60).

Case-Control Studies↗
PubMedDate not supplied

Use of the crown competition factor concept to select clones and spacings for short-rotation woody crops.

Plantation spacing and rotation age are interrelated critical factors in optimizing production of short-rotation woody crops (SRWC). Different genotypes have different spacing and rotation-age optima. I have developed a method for estimating the optimum for new Populus clones based on a modification of the crown competition factor (CCF) concept, which was originally developed for conventional forestry practices with older trees. Measurements of as few as 100 trees of a new clone over a relatively short time period could be used to predict the optimum spacing and rotation age combinations for that clone. The technique could also be used to quantify basic differences in crown architecture and yield physiology among genotypes. One set of at least 20 trees is planted at an open-grown spacing and measured annually for crown and basal stem diameters. The regression of crown diameter on stem diameter is used to calculate the land area that would be occupied per open-grown tree at various stem diameters. This allows prediction of the spacing needed to reach the minimum density for maximum stand growth at a given age or stem size. A second set of 80 measurement trees is planted in a closely spaced set of Nelder arcs to force overstocking within the first few years of growth. Productivity measurements on these trees establish the upper limit on CCF for maximum stand growth. The data are then used to calculate the best spacing and rotation age combination for a new clone. Application of this model may lead to a better understanding of the productive advantages of the sylleptic branch habit, different branch angles and seasonal growth rates, different carbon allocation strategies, and responses to competition.

Journal Article↗
PubMedDate not supplied

Seed orchards in development.

This paper reviews the role of seed orchards as output systems for genetic improvement programs. In this paper, technological changes since the 1950s are examined, with emphasis on recent developments. The need to equate the type of seed orchard to the type of forestry practiced is recognized, as is the significance of the relationship between seed orchards and other output systems for genetically improved material.

Journal Article↗
PubMedDate not supplied

Water use efficiency of short-rotation Salix viminalis at leaf, tree and stand scales.

Fluxes of water and carbon dioxide from short-rotation Salix viminalis L. were measured at leaf, tree and stand scales using porometer, chamber and micrometeorological techniques, respectively. At all three scales, instantaneous water use efficiency exhibited a similar dependence on vapor pressure deficit (deltae) with values of 21, 13 and 10 g CO(2) per kg H(2)O for deltae of 0.5, 1.0 and 1.5 kPa, respectively. The fluxes of CO(2) and H(2)O plotted against incident light above the stand differed in magnitude according to scale, with highest and lowest values being obtained for leaf- and stand-level measurements, respectively. At the tree level, the fluxes of CO(2) and H(2)O reflected the social position of the sample trees with the dominant tree having higher values than the subdominant tree. Average long-term water use efficiency, estimated from stand-level measurements, was 6.3 g dry biomass per kg of transpired water. This value is high compared with values for other tree species and may be associated with a high foliar nitrogen concentration. We conclude that water availability will be a critical factor in short-rotation willow forestry despite the relatively high water use efficiency of the species.

Journal Article↗
PubMed1996

Growth, shoot phenology and physiology of diverse seed sources of black spruce: II. 23-year-old field trees.

Four sources of 23-year-old black spruce (Picea mariana (Mill.) B.S.P.) from a provenance test at the Petawawa National Forestry Institute (46 degrees N, 77 degrees 30' W) were assessed for height growth, shoot phenology and seasonal gas exchange. The provenances were designated 7000 (Yukon, 63 degrees 34' N, 135 degrees 55' W), 6979 (Alberta 52 degrees 22' N, 115 degrees 15' W), 6908 (Ontario, 48 degrees 59' N, 80 degrees 38' W) and 6901 (Ontario, 45 degrees 10' N, 77 degrees 10' W). Trees of southern provenances (6901 and 6908) were considerably taller, and broke bud and ceased growth later than trees of northern provenances (6979 and 7000). In early spring, trees of northern provenances had higher net photosynthetic rates (P(n)) than trees of southern provenances (6908 and 6901). During midsummer, trees of Provenance 7000 generally had the highest P(n) as a result of low rates of shoot dark respiration (R(d)). Trees of northern provenances displayed an earlier autumn decline in P(n) than trees of southern provenances. Provenance differences in growth, shoot phenology and physiology agreed well with results from a greenhouse study of seedlings from the same provenances. We conclude that the poor growth performance of trees of northern provenances in Ontario was associated with: (1) a short period of shoot growth, (2) a high rate of dry matter partitioning to roots, (3) low rates of late-season P(n) in response to decreasing photoperiod, and possibly, (4) a high rate of root R(d).

Journal Article↗
PubMed2000

Process-based models for forest ecosystem management: current state of the art and challenges for practical implementation.

Recent progress toward the application of process-based models in forestmanagement includes the development of evaluation and parameter estimation methods suitable for models with causal structure, and the accumulation of data that can be used in model evaluation. The current state of the art of process modeling is discussed in the context of forest ecosystem management. We argue that the carbon balance approach is readily applicable for projecting forest yield and productivity, and review several carbon balance models for estimating stand productivity and individual tree growth and competition. We propose that to develop operational models, it is necessary to accept that all models may have both empirical and causal components at the system level. We present examples of hybrid carbon balance models and consider issues that currently require incorporation of empirical information at the system level. We review model calibration and validation methods that take account of the hybrid character of models. The operational implementation of process-based models to practical forest management is discussed. Methods of decision-making in forest management are gradually moving toward a more general, analytical approach, and it seems likely that models that include some process-oriented components will soon be used in forestry enterprises. This development is likely to run parallel with the further development of ecophysiologically based models.

Journal Article↗
PubMed2003

Reinvigoration of Pinus radiata is associated with partial recovery of juvenile-like polyamine concentrations.

Polyamine concentrations in consecutive radiata pine (Pinus radiata D. Don) grafts of 30-year-old trees on 1-year-old seedling rootstocks were analyzed by high performance liquid chromatography coupled with fluorescence detection to determine whether reinvigoration is associated with the recovery of polyamine concentrations typical of those in juvenile tissues. Reinvigoration of radiata pine was correlated with the attainment of some, but not all, polyamines characteristic of juvenile trees. In response to reinvigoration, free putrescine, the ratio of free polyamines to low molecular weight polyamine conjugates, and the relative content of putrescine versus spermidine plus spermine increased to values approaching those characteristic of juvenile tissue. In contrast, there was no noticeable change in the concentrations of low molecular weight polyamine conjugates during reinvigoration even though these conjugates increased greatly during tree maturation. We conclude that certain polyamines defined as reinvigoration markers can be used in forestry upgrading programs to assess the morphogenic ability of reinvigorated trees.

Biogenic Polyamines↗
PubMed2005

Bayesian calibration of process-based forest models: bridging the gap between models and data.

Process-based forest models generally have many parameters, multiple outputs of interest and a small underlying empirical database. These characteristics hamper parameterization. Bayesian calibration offers a solution to the calibration problem because it applies to models of any type or size. It provides parameter estimates, with measures of uncertainty and correlation among the parameters. The procedure begins by quantifying the uncertainty about parameter values in the form of a prior probability distribution. Then data on the output variables are used to update the parameter distribution by means of Bayes' Theorem. This yields a posterior calibrated distribution for the parameters, which can be summarized in the form of a mean vector and variance matrix. The predictive uncertainty of the model can be quantified by running it with different parameter settings, sampled from the posterior distribution. In a further step, one may evaluate the posterior probability of the model itself (rather than that of the parameters) and compare that against the probability of other models, to aid in model selection or improvement. Bayesian calibration of process-based models cannot be performed analytically, so the posterior parameter distribution must be approximated in the form of a representative sample of parameter values. This can be achieved by means of Markov Chain Monte Carlo simulation, which is suitable for process-based models because of its simplicity and because it does not require advance knowledge of the shape of the posterior distribution. Despite the suitability of Bayesian calibration, the technique has rarely been used in forestry research. We introduce the method, using the example of a typical forest model. Further, we show that reductions in parameter uncertainty, and thus in output uncertainty, can be effected by increasing the variety of data, increasing the accuracy of measurements and increasing the length of time series.

Algorithms↗
PubMed1989

Solar equivalent leaf area: an efficient biometrical parameter of individual leaves, trees and stands.

The solar equivalent leaf area (A(s)), a simply and easily determined biometrical parameter of leaves, trees and stands, was derived theoretically. The parameter is defined as projected leaf area weighted for the time integral of irradiance at a given location in the canopy relative to that of fully irradiated leaves at the top of the canopy. The efficiency of A(s) as a basis for estimating stand-area transpiration of a mature oak (Quercus robur L.) forest from measurements of transpiration by individual trees was compared with that of other stand and tree characteristics. Stand transpiration estimates based on A(s) were more precise and less prone to systematic error than estimates based on basal area, timber volume, projected tree crown area, projected leaf area, or leaf dry mass. Solar equivalent leaf area reflects both the amount and the physiological properties of leaves and can be used as a measure of tree size and functional capacity. It can be calculated from ordinary forest inventory data on trees and stands, adjusted according to simple phyllometric data. It appears to have wide application in ecological and forestry studies for relating the physiological characteristics of individual leaves to those of entire trees or stands.

Journal Article↗
PubMed1995

Parental occupations as risk factors for craniosynostosis in offspring.

In a population-based case-control study, we examined relations between maternal and paternal occupations and the risk of infant craniosynostosis. Cases were 212 children born to Colorado residents and diagnosed during 1986-1989 with radiographically confirmed synostosis of unknown etiology. Controls were 291 children randomly selected from state birth records and frequency matched to cases on month and year of birth. Trained staff conducted telephone interviews of mothers of case and control children. Information was obtained about each job held by either parent during the pregnancy, and any job that the father held during the 3 months before the last menstrual period before conception. Jobs were coded using 1980 Census occupation and industry codes. We found no strong associations for maternal occupations. Of paternal occupations, two groups were associated with moderately increased odds ratios after adjustment for maternal smoking and altitude: agriculture and forestry (odds ratio = 2.3; 95% confidence interval = 1.0-5.2), and mechanics and repairmen (odds ratio = 2.7; 95% confidence interval = 1.2-6.1). For both, the odds ratios were higher for males.

Adolescent↗
PubMed1995

Evaluation of vision services delivered by a mobile eye clinic in Costa Rica.

A number of private voluntary organizations provide mobile eye services to underserved populations in the developing world. This paper seeks to determine what segment of the population makes use of mobile vision clinics and whether the clinics are identifying significant eye conditions previously undetected by local eye care providers. The population studied were those attending the 1989 vision screening project conducted in rural Costa Rica by members of Volunteer Optometric Services to Humanity (VOSH). Sources of data include patient records of clinic attendees (N = 1530), patient interviews, and Costa Rican census data. Most of the clinic attendees were female (56.9%), over 35 years of age, and literate (71.1%). The three most commonly stated occupation categories were (1) housewife; (2) agriculture, forestry, or fishery worker; and (3) student. Over one-half reported having had a previous eye examination. Presbyopia and low hyperopia were the predominant refractive conditions encountered. Over one-third of patients presented with visual acuities 6/15 (20/50) or worse, and one-third of this group had never had an eye examination. Three-quarters of the patients required prescription lenses and over 20% had cataract. The dispensing of presbyopic corrections to first time patients is clearly the most valuable service provided by the clinics. Teaming up with mobile cataract camps may improve the access to surgical care for patients with cataract. It is important that mobile vision projects target future efforts toward those likely to be missed by conventional screenings.

Adolescent↗
PubMed1989

Occupational risks for brain cancer: a New Zealand Cancer Registry-based study.

Occupational risks for brain cancer were evaluated in a New Zealand Cancer Registry-based case-control study. The case subjects were 452 men aged 20 years or older registered under classifications 191 (Cancer of the brain) and 192 (Cancer of other and unspecified parts of the nervous system) of the International Classification of Disease (9th ed) from 1980 to 1984 for whom occupational information was available. The remaining 19,452 men with other cancers registered during an excess of professional and technical workers. An increased risk among workers in agriculture, forestry, and fishing was due to an excess of brain cancer in farmers, with the highest risk found for livestock farmers. Although many comparisons have been made, some of the findings support previous studies and several new hypotheses are suggested.

Adult↗
PubMed1996

Machinery-related occupational fatalities in the United States, 1980 to 1989.

The National Traumatic Occupational Fatalities surveillance system identified machinery-related incidents as the second leading cause of traumatic occupational fatalities in the United States between 1980 and 1989. These incidents resulted in 8,505 civilian worker deaths and an average annual fatality rate of .80 per 100,000 workers. Workers aged 65 years and older had 5.8 times the fatality rate of workers aged 16 to 64 years (4.06 vs. 70). The highest industry-specific rate was noted in agriculture, forestry, and fishing (7.47). Tractors and other agricultural machinery were associated with nearly 9 of every 10 fatal machinery-related incidents involving workers aged 65 or older. Although numerous studies of agricultural machinery-related fatalities are found in the literature, detailed analyses of machinery-related fatalities in the construction industry as well as analyses of work situations and risk factors associated with fatal injuries are needed.

Accidents, Occupational↗