PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-25 (457545)

Clipboard (0)
None

Related Articles

1.  Space electric field concentrated effect for Zr:SiO2 RRAM devices using porous SiO2 buffer layer 
Nanoscale Research Letters  2013;8(1):523.
To improve the operation current lowing of the Zr:SiO2 RRAM devices, a space electric field concentrated effect established by the porous SiO2 buffer layer was investigated and found in this study. The resistive switching properties of the low-resistance state (LRS) and high-resistance state (HRS) in resistive random access memory (RRAM) devices for the single-layer Zr:SiO2 and bilayer Zr:SiO2/porous SiO2 thin films were analyzed and discussed. In addition, the original space charge limited current (SCLC) conduction mechanism in LRS and HRS of the RRAM devices using bilayer Zr:SiO2/porous SiO2 thin films was found. Finally, a space electric field concentrated effect in the bilayer Zr:SiO2/porous SiO2 RRAM devices was also explained and verified by the COMSOL Multiphysics simulation model.
doi:10.1186/1556-276X-8-523
PMCID: PMC3881491  PMID: 24330524
RRAM; Porous SiO2; Space charge limited current; Zr
2.  Baritosis: a benign pneumoconiosis. 
Thorax  1976;31(1):30-39.
Baritosis is one of the benign pneumoconioses in which inhaled particulate matter lies in the lungs for years without producing symptoms, abnormal physical signs, incapacity for work, interference with lung function, or liability to develop pulmonary or bronchial infections or other thoracic disease. Owing to the high radio-opacity of barium, the discrete shadows in the chest radiograph are extremely dense. Even in the most well-marked cases with extreme profusion of the opacities, massive shadows do not occur. When exposure to barium dust ceases the opacities begin slowly to disappear. Nine cases of baritosis occurring in a small factory in which barytes was crushed, graded, and milled are described. Two of the cases occurred after only 18 and 21 month's exposure, and 9 of the 10 men employed for more than one and a half years had baritosis. Five of the affected men examined at intervals since their exposure to barytes ceased in 1964 showed marked clearing of their radiological abnormalities.
Images
PMCID: PMC470358  PMID: 1257935
3.  Classification of progressive massive fibrosis of coalminers by type of radiographic appearance. 
In a pilot study the chest radiographic appearances of 112 coalminers who developed progressive massive fibrosis (PMF) over an 11 year period have been classified into six types based on the appearances of the large radiographic opacities. The most common type of PMF was one or more large shadows of homogeneous radiodensity. Less common types included markedly rounded shadows usually less than 3 cm in diameter, non-homogeneous shadows appearing to consist of conglomerations of small rounded opacities, and condensations of linear or streaky shadows. Good reproducibility by one reader between two readings were obtained. The lifetime exposures to mixed respirable coal mine dust, and to its quartz component, of these 112 men were compared with those of control subjects matched for age and starting category of simple pneumoconiosis but without PMF. Overall, the men with PMF had been exposed to more mixed dust than controls, confirming that one of the reasons some men with simple pneumoconiosis develop PMF is that they have inhaled more dust than others. Eleven of the 112 cases had large opacities that were not homogeneous and appeared to consist of conglomerations of "r" type small rounded opacities. The average quartz exposures of these men were much higher than in control subjects, suggesting that in this type of PMF quartz was an important causative factor.
Images
PMCID: PMC1069354  PMID: 6743580
4.  Bronchial disease in ulcerative colitis. 
Thorax  1980;35(8):581-585.
Ten patients with ulcerative colitis, all of whom were non-smokers, presented with a productive cough. In six, the chest radiography was normal and cough was the only symptom; three of these patients had a minor obstructive ventilatory defect on testing. Four patients complained of exertional dyspnoea and had both an abnormal chest radiograph with bilateral pulmonary shadows and a mixed obstructive and restrictive ventilatory defect. Bronchial epithelial biopsies from four patients (two with and two without pulmonary shadows) revealed basal reserve cell hyperplasia, basement membrane thickening, and submucosal inflammation, changes more usually associated with cigarette smoking. Inhaled beclomethasone diproprionate relieved cough in seven patients. The occurrence of airway epithelial disease in association with ulcerative colitis raises the possibility of a systemic mechanism affecting both bronchial and colonic epithelium. It does not seem likely that sulphasalazine was the cause of the pulmonary syndrome in these subjects.
Images
PMCID: PMC471338  PMID: 7444824
5.  Piezoelectric Driving of Vibration Conveyors: An Experimental Assessment 
Sensors (Basel, Switzerland)  2013;13(7):9174-9182.
Vibratory feeders or vibratory conveyors have been widely used for the transport and orientation of individual parts and bulk materials in many branches of industrial activity. From the designer's standpoint, the current endeavor is to conceive efficient vibratory feeders, satisfying constraints of power consumption, vibration transmission and noise emission. Moreover, the interest in the reduction of maintenance cost is always present. In this context, this paper investigates experimentally the concept of vibratory conveying based on the use of piezoelectric materials for motion generation. A small-size prototype of a linear conveyor, in which lead-zirconate-titanate (PZT) patches are bonded to the resilient elements, is described. One of the main design goals is that the prototype is intended to be fed directly from the electric network, aiming at avoiding the use of electronic equipment for driving. To comply with this feature and, at the same time, enable to adjust the transport velocity, a mechanical device has been conceived in such a way that the first natural frequency of the conveyor can be changed. It is shown that the transport velocity is determined by the proximity between the excitation frequency and the first natural frequency of the conveyor. The experimental tests performed to characterize the dynamic behavior of the prototype are described and the range of transport velocities is determined.
doi:10.3390/sl30709174
PMCID: PMC3758643  PMID: 23867743
vibratory feeder; vibratory conveyor; automation; piezoelectricity
6.  An Interdisciplinary Approach to Measurement 
This meeting had as its theme the importance of good communications between workers in different disciplines. Papers and demonstrations were presented on a range of topics as apparently unrelated as the intraocular pressure, the tension of nitrogen in blood, and the experimental production of mesothelial tumours. In his introduction Dr J C Gilson showed how these were some recent end-products of research into pneumoconiosis. The work of the Pneumoconiosis Research Unit was centred round the properties of airborne dust and the acute and long-term effects of its inhalation. Studies ranged from the immunological responses of coal workers to surveys of men in some of the world's major asbestos fields; the latter were selected on account of the exposure to dust differing from that of workers in the UK in being confined to a single type of fibre. One link between the different studies was the features of the chest radiographs. For rounded opacities these were now read using the ILO Classification which was largely developed at the Unit; Dr Gilson demonstrated a recent extension to include the irregular opacities which are associated with exposure to asbestos.
PMCID: PMC1811010  PMID: 20919069
7.  Pneumoconiosis in Cornish china clay workers. 
A radiological survey of men employed in the china clay industry in Cornwall was carried out in 1977. Each man completed a short questionnaire on respiratory symptoms and smoking habits, his occupational history was determined, and his forced expiratory volume and vital capacity were measured. The radiographs were read independently by three observers, using the 1980 ILO classification. Of the 1728 men in the study, 23 had had dust exposure elsewhere, mostly in tin mining, and were excluded. Readings of the radiographs were available for 1676 men: 77.4% were within category 0, 17.9% in category 1, and 4.7% in categories 2 and 3. In 19 men (1.1%) one or more readers recorded the presence of a large shadow and read it as complicated pneumoconiosis, but in only four men were the readers unanimous. Every job recognised as dusty contributed significantly to the amount of simple pneumoconiosis, and in two jobs the conditions were such that the average worker would reach category 2 in a working lifetime. Smoking appeared unrelated to the radiographic appearance. Vital capacity showed a significant reduction with increasing amount of pneumoconiosis, but not, when this was allowed for, on the duration of exposure in any of the job categories. In addition it depended, as would be expected, on smoking. The effect of one category increase in pneumoconiosis was equivalent to 4.1 years of age in smokers, 3.9 years of age in ex-smokers, and 5.4 years of age in non-smoker. Forced expiratory volume did not decline significantly with amount of pneumoconiosis, so that FEV% VC showed an increase, though not to a significant extent. No extent. No relationship between symptoms and past exposure was detected.
PMCID: PMC1009161  PMID: 6830708
8.  Ventilatory responses of normal subjects to flax dust inhalation: the protective effect of autoclaving the flax. 
A homogeneous batch of dew retted hackled flax was divided into two portions. One was untreated and the other was steamed for 45 minutes at 125 degrees C in three pressure/vacuum cycles in an autoclave. Dust was collected when the two flaxes were separately processed by industrial doubler and stapler machines. From untreated flax 7.2 g of dust was collected per kilogram of flax after two processing operations. From the steamed flax 4.4 g of flax was obtained per kilogram after four operations. A method was devised to disperse the dust in a room to produce dust levels similar to those encountered in a dusty mill (4.5-5.7 mg/m3). Twelve normal volunteers from the managerial staff of the linen industry of Northern Ireland inhaled the dust over six hour periods. With the untreated flax decreases were obtained in mean forced expiratory measurements of 7.6% in FEV1 and 4.5% in FVC (p less than 0.01). A double blind crossover comparison of similar levels of untreated and steamed flax dusts showed 30% less impairment of the forced expirations with steamed than with untreated flax (p less than 0.05). If these responses reflect the long term airway effects of flax dust then the steaming of flax may help in reducing byssinosis.
Images
PMCID: PMC1007450  PMID: 3970886
9.  Measuring Dust Exposure with the Thermal Precipitator in Collieries and Foundries 
The standard thermal precipitator has been modified for field surveys of airborne dust exposure so as to make it more portable. A microprojector is used when assessing the samples and for coal-mine dusts the counts are restricted to the range 0·5 to 5 microns.
In industrial environments the dust concentration appears to vary with a standard deviation of more than 50% of the mean. Part of this variability is due to errors of the thermal precipitator. The standard error of a count of a sample is about 10% to 15% in practical work and the combined effect of this and other errors is that the standard error of a single result is about 15%. However, in practice this can be neglected since the dust concentration itself is so variable. A more important source of error is the bias, due to overlapping among the particles on the cover glasses. The count may give a serious underestimate of the number of airborne particles if high sample densities are used.
The product of average concentration and duration of exposure is probably a good index of the dose of dust retained in a man's lungs. The duration of exposure is measured by a simple time study made at the same time as the concentration is measured.
Samples are taken near workers chosen at random to give unbiased estimates of the dust exposure. Ideally successive samples are taken alongside different workers. However, in a survey at a colliery it was not possible to do this and each day had to be spent with one collier. The mean dust exposure of the coal-getters was 2,860 particle-hours per shift, of those on stone work 2,250 particle-hours per shift, and the remainder had a mean dust exposure of 1,010 particle-hours per shift.
In a survey at a steel works successive samples could be taken alongside different workers. It was found that the dustiness was unrelated to the apparently dusty processes and as the dust was very fine it was suspected that it was the normal atmospheric pollution of the neighbourhood. This was confirmed by samples taken outside.
The cost of such surveys is found to lie between £1 and £2 per sample taken and consequently alternative instruments are being developed which can run unattended for long periods. In future research studies respiratory ventilation as well as dust exposure may be measured over many years, which, combined with periodic medical examinations, would enable the relation between dust exposure and its effects on the men to be determined.
Images
PMCID: PMC1037902  PMID: 13651553
10.  Shadows bordering the lung on radiographs of normal and obese persons 
Thorax  1972;27(2):232-238.
The thickness of the shadows that accompany ribs or border the lungs on the chest postero-anterior radiographs of 22 obese patients and 22 normal-weight subjects was measured, when present, at several rib levels. A similar measurement was made of accompanying rib shadows on chest postero-anterior radiographs of eight obese patients after weight reduction. Statistical analysis showed that there were significantly thicker soft tissue shadows adjacent to the ribs of obese subjects compared to normal-weight persons and of obese subjects before as compared to after weight reduction. Such shadows are more frequent and are seen at more rib levels of the obese.
In addition, the following pertinent features are discussed: the mechanism by which soft tissue projects a radiographic shadow, the factors affecting its appearance, and the significance of such shadows as a variant of the normal chest radiograph and not as a manifestation of pathology.
Images
PMCID: PMC472527  PMID: 5034601
11.  Hut lung: a domestically acquired pneumoconiosis of mixed aetiology in rural women. 
Thorax  1991;46(5):334-340.
A form of pneumoconiosis in rural African women termed "Transkei silicosis" has been thought to be due to silica particles inhaled while they are hand grinding maize between rocks. Twenty five women were studied who were considered to have this condition according to the following criteria: rural domicile, radiographic and lung biopsy evidence of pneumoconiosis, no exposure to mining or industry and no evidence of active tuberculosis. They were assessed for radiological, pathological, physiological and bronchoalveolar lavage fluid features. Potential aetiological factors were assessed by determining levels of exposure to respirable quartz and non-quartz containing dusts and smoke in rural dwellings during maize grinding and cooking. Most of the women were symptomless. Radiological findings ranged from a miliary pattern to extensive fibrosis resembling progressive massive fibrosis. Histological features included simple "anthracosis" in 12, anthracosis with macules in six, and mixed dust fibrosis in seven. Cell numbers and their proportions in lavage fluid were normal. More than 60% of macrophages were heavily laden with inorganic inclusions. Respirable quartz concentrations and calculated cumulative time weighted exposures were below those recommended for industry during grinding with sandstone (100% quartz) and they were even lower during grinding with dolerite containing no quartz despite the presence of an appreciable amount of quartz in the ground maize. Total respirable dust and smoke concentrations were greater than the recommended safe levels. Three women had no exposure to maize grinding. It is concluded that the inhalation of non-quartz containing dust and smoke from biomass fuelled fires is more important in the aetiology of this condition than exposure to quartz dust. The term "hut lung" may be more appropriate.
Images
PMCID: PMC463130  PMID: 2068688
12.  Morphological investigations of fibrogenic action of Estonian oil shale dust. 
A review of morphological investigations carried out to clarify the pathogenicity of industrial dust produced in the mining and processing of Estonian oil shale is given. Histological examination of lungs of workers in the oil shale industry taken at necropsies showed that the inhalation of oil shale dust over a long period (more than 20 years) may cause the development of occupational pneumoconiotic changes in oil shale miners. The pneumoconiotic process develops slowly and is characterized by changes typical of the interstitial form of pneumoconiotic fibrosis in the lungs. Emphysematous changes and chronic bronchitis also occur. The average chemical content of oil shale as well as of samples of oil shale dust generated during mining and sorting procedures is given. The results of experiments in white rats are presented; these studies also indicate a mild fibrogenic action of Estonian oil shale dust.
Images
PMCID: PMC1637705  PMID: 221215
13.  Levels of airborne dust in furniture making factories in the High Wycombe area 
Hounam, R. F. and Williams, J. (1974).British Journal of Industrial Medicine,31, 1-9. Levels of airborne dust in furniture making factories in the High Wycombe area. A dust survey was carried out in five furniture making factories in, or in the vicinity of, High Wycombe. The results, which are among the first to be reported for the United Kingdom, have provided information on the concentrations and size distributions of airborne dust to which wood machinists are currently exposed. Although measured concentrations covered a wide range, the average concentration was similar to the threshold limit value of 5 mg m-3 provisionally recommended by the American Conference of Governmental Industrial Hygienists. A high proportion by mass of the airborne dust was of a size which will be deposited in the nasal passages on inhalation.
Images
PMCID: PMC1009536  PMID: 4821408
14.  Industrial bronchitis. 
For many years there has been much argument whether workers in the dusty trades are prone to chronic bronchitis. In 1966 the Medical Research Council issued a report of a Select Committee which concluded that occupationally induced bronchitis did not play a significant part in the aetiology of airways obstruction in dust-exposed men. Since then epidemiological studies have demonstrated that the prolonged inhalation of dust leads to an increase in prevalence of cough and sputum. Furthermore, new physiological techniques have demonstrated a slight decrement in ventilatory capacity as a result of industrial bronchitis, and which is related to lifetime dust exposure. Unlike bronchitis induced by cigarette smoke, the predominant effect of industrial bronchitis is on large rather than small airways and the condition is not accompanied by emphysema.
PMCID: PMC1008445  PMID: 367424
15.  Cryptogenic fibrosing alveolitis: pattern of disease in the lung. 
Thorax  1984;39(11):857-861.
The distribution of disease has been studied in 10 patients with histologically confirmed cryptogenic fibrosing alveolitis by means of computed tomography of the lungs, gallium 67 uptake scintigraphy, and ventilation and perfusion scintigraphy. The findings of computed tomography and scintigraphy showed no correlation with the UICC/Cincinnati grades of the plain chest radiographs, even when these were supplemented with information from lateral and oblique chest films. Computed tomography showed subpleural shadowing in every patient except one who had responded well to corticosteroid treatment. Subpleural shadowing was commoner in the inferior and posterior parts of the lung lobes and was commonest in the posterior lower subpleural areas. The central lung showed three types of change--firstly, a dense shadowing, which was sometimes associated with much increased gallium uptake; secondly, dilated smaller airways with small bullae, suggesting airway disease; and, thirdly, gross bullous change.
Images
PMCID: PMC459937  PMID: 6505992
16.  Enhanced translocation of particles from lungs by jaggery. 
Environmental Health Perspectives  1994;102(Suppl 5):211-214.
Because industrial workers in dusty or smoky environments seemed to experience no discomfort if they consumed the sugar cane product jaggery, experimental studies were undertaken to observe the effects of jaggery on dust-exposed rats. Rats with and without a single intratracheal instillation of coal dust (50 mg/rat) were orally gavaged with jaggery (0.5 g/rat, 5 days/week for 90 days). The enhanced translocation of coal particles from lungs to tracheobronchial lymph nodes was observed in jaggery-treated rats. Moreover, the jaggery reduced the coal-induced histological lesions and hydroxyproline contents of lungs. The lesions induced in omental tissue and regional lymph nodes by a single intraperitoneal injection of 50 mg each of coal and silica dust were modified by jaggery (0.5 g/rat, 5 days/week for 30 days). These findings along with the preventive action of jaggery on smoke-induced lung lesions suggest the potential of jaggery as protective agent for workers in dusty and smoky environments.
Images
PMCID: PMC1567304  PMID: 7882934
17.  CD11c+/CD11b+ Cells Are Critical for Organic Dust–Elicited Murine Lung Inflammation 
Organic dust exposure in the agricultural industry results in significant lung disease. Macrophage infiltrates are increased in the lungs after organic dust exposures, yet the phenotype and functional importance of these cells remain unclear. Using an established intranasal inhalation murine model of dust-induced lung inflammation, animals were treated once or daily for 3 weeks with swine confinement organic dust extract (DE). Repetitive DE treatment for 3 weeks resulted in significant increases in CD11c+/CD11b+ macrophages in whole lung–associated tissue. These cells displayed increased costimulatory molecule (CD80 and CD86) expression, enhanced phagocytic ability, and an increased production of IL-6, CXCL1, and CXCL2. Similar findings were observed with the CD11c+/CD11b+ macrophage infiltrate after repetitive exposure to peptidoglycan, a major DE component. To determine the functional importance of macrophages in mediating DE-induced airway inflammation, lung macrophages were selectively depleted using a well-established intranasal clodronate liposome depletion/suicide strategy. First, macrophage depletion by clodronate liposomes resulted in significant reductions in airway neutrophil influx and TNF-α and IL-6 production after a single exposure to DE. In contrast, after repetitive 3-week exposure to DE, airway lavage fluid and lung tissue neutrophils were significantly increased in clodronate liposome–treated mice compared with control mice. A histological examination of lung tissue demonstrated striking increases in alveolar and bronchiolar inflammation, as well as in the size and distribution of cellular aggregates in clodronate–liposome versus saline–liposome groups repetitively exposed to DE. These studies demonstrate that DE elicits activated CD11c+/CD11b+ macrophages in the lung, which play a critical role in regulating the outcome of DE-induced airway inflammation.
doi:10.1165/rcmb.2012-0095OC
PMCID: PMC3547108  PMID: 22822029
macrophage; neutrophil; airway inflammation; peptidoglycan; organic dust
18.  Wood Dust Sampling: Field Evaluation of Personal Samplers When Large Particles Are Present 
Annals of Occupational Hygiene  2010;55(2):180-191.
Recent recommendations for wood dust sampling include sampling according to the inhalable convention of International Organization for Standardization (ISO) 7708 (1995) Air quality—particle size fraction definitions for health-related sampling. However, a specific sampling device is not mandated, and while several samplers have laboratory performance approaching theoretical for an ‘inhalable’ sampler, the best choice of sampler for wood dust is not clear. A side-by-side field study was considered the most practical test of samplers as laboratory performance tests consider overall performance based on a wider range of particle sizes than are commonly encountered in the wood products industry. Seven companies in the wood products industry of the Southeast USA (MS, KY, AL, and WV) participated in this study. The products included hardwood flooring, engineered hardwood flooring, door skins, shutter blinds, kitchen cabinets, plywood, and veneer. The samplers selected were 37-mm closed-face cassette with ACCU-CAP™, Button, CIP10-I, GSP, and Institute of Occupational Medicine. Approximately 30 of each possible pairwise combination of samplers were collected as personal sample sets. Paired samplers of the same type were used to calculate environmental variance that was then used to determine the number of pairs of samples necessary to detect any difference at a specified level of confidence. Total valid sample number was 888 (444 valid pairs). The mass concentration of wood dust ranged from 0.02 to 195 mg m−3. Geometric mean (geometric standard deviation) and arithmetic mean (standard deviation) of wood dust were 0.98 mg m−3 (3.06) and 2.12 mg m−3 (7.74), respectively. One percent of the samples exceeded 15 mg m−3, 6% exceeded 5 mg m−3, and 48% exceeded 1 mg m−3. The number of collected pairs is generally appropriate to detect a 35% difference when outliers (negative mass loadings) are removed. Statistical evaluation of the nonsimilar sampler pair results produced a finding of no significant difference between any pairing of sampler type. A practical consideration for sampling in the USA is that the ACCU-CAP™ is similar to the sampler currently used by the Occupational Safety and Health Administration for purposes of demonstrating compliance with its permissible exposure limit for wood dust, which is the same as for Particles Not Otherwise Regulated, also known as inert dust or nuisance dust (Method PV2121).
doi:10.1093/annhyg/meq075
PMCID: PMC3037778  PMID: 21036895
ACCU-CAP™; Button sampler; CIP10-I sampler; GSP sampler; inhalable sampling; IOM sampler; wood dust
19.  Small animals in the study of pathological effects of asbestos 
The main pathological effects attributed to asbestos are carcinogenesis and fibrogenesis. Statistical studies have shown that asbestos workers may expect a higher morbidity not only from cancer of the lung and mesothelioma but also from cancer at other sites. Carcinomas have been reported in animals following the injection of asbestos, but the production of carcinomas by inhaled asbestos is less easy to demonstrate; most examples of experimental carcinogenesis with asbestos have been produced in rats. Rats and man react differently to asbestos in that rats do not produce asbestos bodies.
The fibrosis that follows inhalation of asbestos has been frequently described, but studies with specific pathogen free animals have shown that, like the fibrosis that may follow the inhalation of silica dust, gross fibrosis involving the production of abnormal amount of collagen probably requires the intervention of infection as well as asbestos.
Because of the difficulties encountered in the direct investigation of carcinogenesis and fibrogenesis resulting from the inhalation of asbestos, attention has been directed to the mechanisms by which the lung is able to protect itself against these fibrous dusts. While non-fibrous dusts and short fibers can be ingested by macrophages and removed via the bronchus, the long fibers that may also reach the alveolar regions may not be removed by this mechanism. The probability that a fiber may reach the alveoli depends largely on the fiber diameter and only to a small extent on the fiber length, so that, for example, fibers 100 μm long may reach the alveoli of a guinea pig. These long fibers may become coated with a ferroprotein derived from hemoglobin to form an asbestos body and, after morphological changes, the asbestos body may be broken up, the fragments ingested by macrophages and dissolved. The lung is thus cleared of asbestos. In the guinea pig lung, consolidated areas from which the asbestos has disappeared shows signs of return to normal.
This clearance mechanism is inhibited by other factors: quartz dust may almost completely inhibit asbestos body formation; tobacco smoke has a considerable effect, and even very heavy loads of carbon may act similarly.
The normal lung appears able to efficiently eliminate small loads of both nonfibrous and fibrous dust, including the carcinogenic asbestos fibers. The capacity is not unlimited, however, and when the load is heavy there is a much greater probability that fibers will not be detoxicated. In addition, other factors such as silica dust and tobacco smoke may remove the protective mechanism in the lungs.
Images
PMCID: PMC1475401  PMID: 4377872
20.  The biology of talc. 
Data are presented on the effects on health of talc dusts from exposure in industry and use of talc-containing health products. The mineralogy of talc and the composition of cosmetic and industrial grade talc dusts are described. Studies in animals are reviewed, and epidemiological data are considered in relation to exposures that occur during industrial and consumer uses of talc dusts. Hamsters exposed to 8 mg/m3 of respirable cosmetic grade talc dust for up to 150 minutes a day for 300 consecutive days showed no difference in incidence or nature of pathological lesions from those observed in a group of untreated animals. A retrospective study of the causes of death of 227 talc mine millers exposed to cosmetic grade talc at the threshold limit value for talc (20 million parts per cubic foot) for an average of 15-8 years showed that the causes of death were no different from those in a control cohort not exposed to talc dust. The available data indicate that talc dust exposure in the modern mining of cosmetic grade talc does not appear to be injurious to health. The significantly lower dust exposure in the normal use of cosmetic grade talc dusts in talc-containing health and cosmetic products confirms that their use is not a hazard to health.
PMCID: PMC1008143  PMID: 793610
21.  Respiratory disease caused by synthetic fibres: a new occupational disease. 
Thorax  1975;30(2):204-219.
Seven patients exposed to the inhalation of synthetic fibres presented with various bronchopulmonary diseases, such as asthma, extrinsic allergic alveolitis, chronic bronchitis with bronchiectasis, spontaneous pneumothorax, and chronic pneumonia. The histological features are described and an attempt has been made to set up immunological techniques for the diagnosis. A series of histochemical techniques, based on textile chemistry, are proposed for the identification of the inclusions found in bronchopulmonary lesions. The results of the experimental production of the disease in guinea-pigs by the inhalation of synthetic fibre dusts are presented. The prognosis of these cases is good in the acute or recently established cases but is poor when widespread and irreversible fibrosis has set in. The authors consider that pulmonary disease due to inhaled particles is probably set off by an individual factor, possibly immunological.
Images
PMCID: PMC470268  PMID: 1179318
22.  The Role of Bacterial Endotoxins in Occupational Diseases Caused by Inhaling Vegetable Dusts 
A large group of occupational diseases connected with the inhalation of various vegetable dusts, especially in the textile industry, have certain main symptoms in common such as fever, coughing, dyspnoea, and general malaise. In most cases the symptoms are more prominent on Mondays or on resuming work after one or more days of interruption. The symptomatology of these diseases and the Monday effect leads to the hypothesis that they are due to the inhalation of the endotoxins of gram-negative bacteria that contaminate the various vegetable materials, the Monday effect being connected with the phenomenon of tolerance to the endotoxins. Support for this view came from the demonstration of the constant presence of endotoxins in cotton dusts in textile mills and from the study of the effects of the inhalation of purified endotoxins in rabbits and man.
Images
PMCID: PMC1038103  PMID: 13734460
23.  Recent trends in bagassosis in Japan. 
The only workers presently exposed to bagasse dust in Japan are the employees of sugar refineries and lacquerware factories. A follow up study of six former cases of bagassosis from among the retired employees of a paper board factory, closed since 1973, showed that none of the subjects still had bagassosis. Examinations of 70 employees of a sugar refinery for allergic reactions also showed no case of bagassosis. Seven cases with suspicious shadows of bagassosis on chest radiographs and four cases with positive serum precipitin to stored bagasse were, however, found among those 70 subjects. The results show the disappearance of a past episode of bagassosis and the possibility of a new occurrence of bagassosis among the employees of sugar refineries and lacquerware factories in the near future in Japan.
Images
PMCID: PMC1039272  PMID: 1637710
24.  Agricultural seed dust as a potential cause of organic dust toxic syndrome 
Aims
Episodes of serious work related health problems resembling organic dust toxic syndrome (ODTS) in workers of a grass seed quality inspection laboratory prompted the authors to study personal endotoxin exposure levels in this facility and in the agricultural seed processing industry. In addition, microbial and inflammatory characteristics of agricultural seeds were studied.
Methods
The authors assessed inhalable dust and endotoxin levels in 101 samples from 57 workers in grass, cereal, and vegetable seed plants who were handling mainly grass seeds as bulk product, and horticulture seeds in smaller quantities. Additionally, real‐time dust exposure was measured using a DataRAM monitor in 12 grass seed workers to obtain more information on exposure patterns during specific tasks. Endotoxin concentrations in seed extracts were determined by LAL assay and seed samples were analysed by scanning electron microscopy. Release of inflammatory cytokines was measured in supernatants of whole blood samples stimulated with lipopolysaccharide (LPS) or agricultural seed extracts in a human whole blood assay (WBA).
Results
Endotoxin concentrations in personal samples were high (geometric mean 1800 EU/m3), particularly in the grass seed quality inspection lab where endotoxin levels up to 274 000 EU/m3 were measured. The recommended health based endotoxin exposure limit of 50 EU/m3 was amply exceeded in almost all personal samples. Job tasks dumping and mixing were associated with highest dust and endotoxin exposures, which was confirmed by real‐time measurements. Microbial infestation was found in almost all seed samples. WBA results showed that most seed extracts were capable of inducing a pronounced dose dependent cytokine release.
Conclusions
Workers handling grass, cereal, or vegetable seeds are at risk of exposure to high levels of endotoxin containing seed dust. Occupational exposure to inhalable agricultural seed dust can induce inflammatory responses, and is a potential cause of ODTS.
doi:10.1136/oem.2005.021527
PMCID: PMC2078022  PMID: 16361407
endotoxin; occupational exposure; agricultural seed processing industry; ODTS; whole blood assay
25.  Inhalation of stable dust extract prevents allergen induced airway inflammation and hyperresponsiveness 
Thorax  2005;61(2):134-139.
Background
Recent epidemiological studies have shown that growing up on a traditional farm provides protection from the development of allergic disorders such as hay fever and allergic asthma. We present experimental evidence that substances providing protection from the development of allergic diseases can be extracted from dust collected in stables of animal farms.
Methods
Stable dust was collected from 30 randomly selected farms located in rural regions of the Alps (Austria, Germany and Switzerland). The dust was homogenised with glass beads and extracted with physiological sodium chloride solution. This extract was used to modulate immune response in a well established mouse model of allergic asthma.
Results
Treatment of mice by inhalation of stable dust extract during sensitisation to ovalbumin inhibited the development of airway hyperresponsiveness and airway eosinophilia upon challenge, as well as the production of interleukin 5 by splenocytes and of antigen specific IgG1 and IgE. Dust extract also suppressed the generation of human dendritic cells in vitro. The biological activity of the dust extract was not exclusively mediated by lipopolysaccharide.
Conclusions
Stable dust from animal farms contains strong immune modulating substances. These substances can interfere with the development of both cellular and humoral immunity against allergens, thus suppressing allergen sensitisation, airway inflammation, and airway hyperresponsiveness in a murine model of allergic asthma.
doi:10.1136/thx.2005.049403
PMCID: PMC2104583  PMID: 16244088
allergen sensitisation; animal model; asthma; hygiene hypothesis

Results 1-25 (457545)