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PubMed1988

Activation of guinea pig lymphocytes and mast cells by grain-dust extract.

Previous studies have demonstrated that grain dust can stimulate lymphocyte proliferation and the production of interleukin-1 by macrophages. This study was undertaken to investigate whether grain dust could stimulate the production of histamine-releasing factor (HRF) by guinea pig spleen cells. We also studied the direct action of grain dust on guinea pig lung mast cells and basophils. Plastic nonadherent cells from immunized animals were cultured for 24 hours in the presence of grain dust or lipopolysaccharide, and the cell-free supernatants were assayed for HRF activity in the mast cell and basophil histamine release test. Lung mast cells were isolated by enzymatic digestion and discontinuous Percoll gradient centrifugation. It has been demonstrated that grain dust stimulated the production of HRF by spleen cells from the immunized animals but not from the control animals. Stimulation of spleen cells with lipopolysaccharide did not enhance the HRF production. Gel chromatography of grain dust-stimulated supernatant revealed that HRF has a molecular weight in the range of 50 to 70 kd and 5 to 8 kd. We also found that grain dust directly released significant amount of histamine from both mast cells and basophils. The results of this study suggest that grain dust contains some potent active substances that can activate lymphocytes, mast cells, and basophils.

Animals↗
PubMed1987

Total concentrations of dust in the air during farm work.

Total concentrations of dust in the air of work environments were measured on 20 Finnish farms during 1980-82. On 8 farms the main line of production was dairy farming, on 5 farms it was pig farming, on 4 farms poultry farming and on 3 farms grain production. Dust was measured by the gravimetric method according to the Finnish standard. Results were compared to the threshold limit value (TLV), which for inorganic dust is 10 mg/m3, and for organic dust 5 mg/m3. Mean concentrations of dust in the breathing zone exceeded the TLV for organic dust in all farm buildings, piggeries and poultry yards with coops having the highest mean concentrations, 12.6 mg/m3 and 12.8 mg/m3, respectively. Mean total concentrations of dust during seed dressing, harrowing, rolling and emptying the grain drier were 31.4, 14.0, 18.2 and 20.0 mg/m3, respectively. During sowing and haymaking, the total concentrations of dust were also high occasionally.

Agricultural Workers' Diseases↗
PubMed1986

Allergen avoidance in house dust mite sensitive adult asthma.

Fifty adult asthmatic patients with strongly positive skinprick tests to the house dust mite were admitted into a prospective randomised controlled trial of house dust mite avoidance in the community. Twenty-two of the experimental group completed one year of dust avoidance and 19 of these tolerated the use of plastic mattress and pillow covers. Twenty of the control group (who did not alter their housecleaning habits) also completed one year of study. A fall in mite and dust levels was noted in the homes of the experimental but not the control group. Fifteen of the experimental group who completed the study were strongly RAST positive (score 3 or more) to the house dust mite. These patients had a significant improvement in FEV1/FVC, PEFR, PC20, use of treatment, and symptom score at one year, whilst the seven experimental patients who were not strongly RAST positive (score 2 or less) did not, suggesting that the change noted in the former patients was not merely due to a placebo effect. Fifteen of the control group who completed the study were also strongly RAST positive for the house dust mite and these patients showed no change in any of the parameters. This study demonstrates that adult asthmatic patients can successfully carry out house dust eradication procedures in the community over a long period of time, and that those patients who are allergic to the house dust mite appear to have both subjective and objective improvement in their asthma.

Adult↗
PubMed1982

[Histochemical mechanisms in etiology of pulmonary fibrosis after short-term exposure to a mixture of dust and quartz from copper mine].

The authors induced pulmonary silicosis in albino rats by the intratracheal method with 50 mg mixed middling slime from Panaguiriste and quartz dust, dissolved in I ml physiological solution. The animals received a single treatment and were killed on 90th day of the experiment. Some intime characteristics of collagen-forming mechanisms in lungs were followed up via routine histological, histochemical, enzymohistochemical/ acid phosphatase activity, beta-glucoronidase, AS-esterase and lipase/ and autoradiographic/H3 labelled proline/ methods. It was established, that under the effect of both dusts from Panaguiriste mines studied/ mixed dust and pure quartz dust/ considerable deviations developed in the structure of the lungs of the experimental animals in the enzyme activity of acid phosphatase and carbon esterase, accompanied by various forms of fibrosis in the organ, depending on the dust applied. The difference in the composition of both dusts quartz and mixed dust slime - had an effect on the degree of the deviations, but not on their character, manifested in: I. specific protective reaction of organism, with activation of the ferments from the group of carbon esterase in macrophagic elements of interstitium and around the silicotic alterations in the lungs of the experimental animals; 2. inhibition of the maturation of macrophages in silicotic foci and 3. acceleration of the proliferation of fibroblasts with intensification of collagen-formation, accompanied by an enhanced activity of the ferments from the group of carbon esterase and in the cytoplasm of fibroblasts. The authors draw the conclusion that the complex use of routine histological, histochemical and quantitative isotope methods enables the more significant determination of fibrinogenicity of quartz-containing dust even at the early terms of their exposure under experimental conditions.

Acid Phosphatase↗
PubMed1984

[Intrapulmonary reactions of workers exposed to dust and ozone].

Forty-one dust-and-ozone-exposed and 37 nonexposed workers, belonging to the Research and Development Division of a photo-copier manufacturing industry, were examined to assess the effect of the exposure to carbon, iron and resin dust and ozone in the air of the work environment by means of questionnaires on their physical condition, smoking habits and exposure history by interview, chest X-rays, testing of ventilatory functions, transcutaneous PO2 (tcPO2) test and H2O2-induced hemolysis test. The following results were obtained. Respirable dust concentrations in the air of the work place were 0.1-1.0 mg/m3, total dust concentrations 0.2-2.0 mg/m3, and ozone concentrations 0.004-0.06 ppm (0.008-0.12 mg/m3). According to the Japanese Classification of Radiographs of Pneumoconioses, the exposed workers showed a higher rate of profusion 0/1 and over, and category 1 and over (1/0 and over) than the nonexposed workers. Ventilatory function testing revealed no difference between exposed workers and nonexposed workers, but small airway narrowing was suspected in smoking workers in comparison with nonsmoking workers. Transcutaneous PO2 showed no difference between exposed and nonexposed workers, between smoking and nonsmoking workers, and between any of the paired six combinations out of the four groups of workers, i.e., nonsmoking and nonexposed, nonsmoking and exposed, smoking and nonexposed, and smoking and exposed. It was estimated by H2O2-induced hemolysis test that smoking and/or dust exposure, especially long-term exposure, gave rise to aggravation of fragility of the erythrocyte membrane by lipid peroxidation with ozone or active oxygen produced by the reaction of dust and alveolar macrophages. The questionnaire was considered indispensable to ascertain the workers' exposure history. No worker in this work environment showed clinical signs indicating a need for medical care or home response. There results may indicate that in resolving the pathogenesis of pneumoconiosis further studies will be required on the prevalence rate of profusion 0/1 and over (or category 1 and over) under low concentrations of dust exposure and on the intrapulmonary reactions induced by low doses of dust exposure.

Adult↗
PubMed1984

Emphysema and dust exposure in a group of coal workers.

The lungs of 450 coal miners who had been studied previously in a long-term epidemiologic project at 24 British mines have been examined post-mortem for signs of dust-related fibrosis and emphysema. Reliable estimates of cumulative (working-life) exposures to respirable mine dust were available for 342 of the men. The relative frequency of emphysema increased with age at death, and both panacinar and centriacinar emphysema occurred more frequently in smokers than in nonsmokers. The proportion of subjects with any emphysema was 47% in 92 men with no palpable dust lesions, 65% in 183 with small, simple pneumoconiotic lesions, and 83% in 175 miners with massive fibrosis (PMF). The chance of finding centriacinar emphysema in those with PMF increased significantly with increasing exposure to coal dust in life (p less than 0.025). A similar but less convincing relationship was found in those with simple pneumoconiosis (p less than 0.11), but in both groups, increasing amounts of ash with a given exposure to coal reduced the probability of finding centriacinar emphysema. The occurrence of centriacinar emphysema was associated also with increasing amounts of dust retained in the lungs. A preliminary exploration of this association did not support the hypothesis that emphysematous lungs clear dust less efficiently. We conclude that the association observed between exposure to respirable coal dust and emphysema in coal miners indicates a causal relationship. However, because it can be demonstrated only for men whose lungs show some dust-related fibrosis, it is suggested that the extent and nature of such fibrosis may be a crucial factor in determining the presence of centriacinar emphysema.

Age Factors↗
PubMed1980

Estimation of exposure to asbestos-cement dust on building sites.

In the Federal Republic of Germany, about 1.2 million tons of asbestos are handled on building sites, for example, by roofers, carpenters and ventilation fitters. The objective of this study was to determine both the exposure to dust during the handling of asbestos-cement products on building sites and the possible resulting fibrogenic health hazard. In order to assess the tumour risk, this cross-sectional study should be enlarged to a longitudinal study. Dust measurements were made on about 40 building sites with four static and four personal dust samplers and a Tyndallometer. Evaluation was performed by infrared spectrography and light and scanning electron microscopy. Peak concentrations of more than 100 fibres/ml of length greater than 5 micrometers or about 80 mg/m3 fine dust were observed in the vicinity of the grinding machine. The asbestos content of the fine dust was about 10%. Scanning electron microscopy showed a wide variation of fibre lengths and diameters; a large proportion of fibres with diameters below 0.2 micrometers was found. Long-term, mean values and confidence intervals of the concentration of fine dust were calculated from the measurements. For example, the mean fine dust mass concentrations for roofers cutting corners of asbestos-cement sheets with the grinding machine amounted to 2.2 mg/m3 when the cutting was done in the open air at a fixed location. When cutting was performed on the roof, the mean fine dust mass concentration amounted to 1.8 mg/m3.

Air Pollutants↗
PubMed1995

Prevalence of house dust mites in the Rocky Mountain states.

BACKGROUND: Due to low rainfall and high elevation the ten Rocky Mountain states would not be expected to have the indoor humidity required to support the growth of significant numbers of house dust mites. Nevertheless, a recent survey reported that house dust mite allergen levels were not significantly different in the various regions of the United States, including the arid and mountainous regions. METHODS: Each summer for 5 years (1988-92) patients with bronchial asthma scheduled to be evaluated at the National Jewish Center for Immunology and Respiratory Medicine were invited to submit a dust sample from their mattress or bedroom carpet for mite analysis. RESULTS: Fifty-eight patients from the ten Rocky Mountain states submitted dust specimens. Forty-eight contained no mites, five had levels of mites considered clinically insignificant (less than 100 mites/g dust), three contained 100 mites/g of dust, a level at the threshold of significance, and two had high levels of mites (1,000 and 3,000 mites/g). Both of the homes with high mite levels had specific sources of excess moisture. Twenty-eight patients from adjacent states also submitted dust specimens. Significant levels of mites were encountered in specimens from these states reflecting the transition to zones of greater humidity and lower elevation. CONCLUSION: Except in homes with unusual sources of humidity, significant levels of house dust mites are rarely encountered in homes in the ten Rocky Mountain states.

Allergens↗
PubMed1995

Mutagenicity of stable dust and drinking water on swine and cattle farms.

Single pilot examinations of mutagenicity of stable dust and drinking water were made on three swine farms (D., M., T.) and one cattle farm (N.) in the district of Hodonín in summer 1994. The mutagenicity was examined by the Ames test using the indicator strains Salmonella typhimurium TA 98 and TA 100 with (+S9) or without (-S9) metabolic activation. At the same time the contents of selected pesticides (PES) and polychlorinated biphenyls (PCB) in stable dust and drinking water and that of polycyclic aromatic hydrocarbons in stable dust were determined. Increased mutagenicity was demonstrated in drinking water (strain TA 98 with metabolic activation; index Rt/Rk 3.6-7.7) and stable dust (strain TA 100 with metabolic activation; index Rt/Rk 2.2) collected on the swine farm M. High contents of PAH (8.246 mg/kg) and PCB (0.263 mg/kg) were also found in the dust samples collected on this farm. Only drinking water showed mutagenic activity (strain TA 98 without metabolic activation; index Rt/Rk 2.6) on the swine farm D. On both the farms, the number of revertants was dose-dependent. Increased content of PAH (2.553 mg/kg) was also demonstrated on the dust samples collected on the farm D. No significant increase (twofold or higher when compared with negative controls) of mutagenic activity of stable dust or drinking water was demonstrable on the swine farm T. and the cattle farm N. Substances responsible for the mutagenicity of drinking water on the farms D. and M. have not yet been identified. Anyway, the increase of mutagenicity of stable dust and drinking water should be taken as a warning that mutagens that can jeopardise animal and human health have penetrated into the stable environment.

Animals↗
PubMed1996

[Dust emission from chicken and layer houses].

Dust concentration was measured by Laser-monitor in two at a time houses for layers with litter or with cages and in two at a time houses for growing chicken with litter or with cages in the middle of the keeping area, in the outlet opening and in 3, 10, 50 and 100 m distance over a period of 8 weeks in winter, summer and spring/autumn. Dust values have shown only less dynamics between 8 am and 5 pm. Significant positive correlation was found between dust concentration and age of poultry, keeping time resp. in litter housing system but not in cage housing system. Also, it was demonstrated a significant relation between dust concentration inside of poultry house, at the outlet openings and in 3 m distance in the outdoor air. There was no influence evident of indoor dust concentration on the dust value in the environment in more than 3 m distance to the poultry house. It was shown a low dust concentration of 0.1% up to 2.1%--compared to the indoor dust values--in 50 and 100 m distance to outlet ventilation system independent on housing, climatic and topographic factors.

Aging↗
PubMed1996

Silicate and metal dust in lungs of Greyhounds.

OBJECTIVES: To determine whether the amount of opaque dust in lung specimens increases with age, the composition of that dust, and whether the composition is similar for Greyhounds and pet dogs. DESIGN: Quantification of lung particulate dust burdens. ANIMALS: 192 Greyhounds and 5 pet dogs. PROCEDURE: Lung specimens of 192 Greyhounds and 5 pet dogs were examined for dust accumulation, using light microscopy. Lung specimens from Greyhounds and the 5 pet dogs were analyzed, using scanning electron microscopy and energy dispersive x-ray spectroscopy to quantify the lung burden of inorganic particles. RESULTS: Lung dust burden increased linearly with age. Pulmonary dust was composed of aluminum silicates, silica, and 18 metals. Silicate and metal particulate burdens were higher in Greyhounds than in the pet dogs. The 3 most common metals were iron, titanium, and chromium. CONCLUSIONS AND CLINICAL RELEVANCE: Amount of opaque dust increased with age. The higher pulmonary dust burden in Greyhounds than in pet dogs suggests that environmental exposure is important.

Animals↗
PubMed2003

Type II supernovae as a significant source of interstellar dust.

Large amounts of dust (>10(8)M(o)) have recently been discovered in high-redshift quasars and galaxies corresponding to a time when the Universe was less than one-tenth of its present age. The stellar winds produced by stars in the late stages of their evolution (on the asymptotic giant branch of the Hertzsprung-Russell diagram) are thought to be the main source of dust in galaxies, but they cannot produce that dust on a short enough timescale (&<1 Gyr) to explain the results in the high-redshift galaxies. Supernova explosions of massive stars (type II) are also a potential source, with models predicting 0.2-4M(o) of dust. As massive stars evolve rapidly, on timescales of a few Myr, these supernovae could be responsible for the high-redshift dust. Observations of supernova remnants in the Milky Way, however, have hitherto revealed only 10(-7)-10(-3)M(o) each, which is insufficient to explain the high-redshift data. Here we report the detection of approximately 2-4M(o) of cold dust in the youngest known Galactic supernova remnant, Cassiopeia A. This observation implies that supernovae are at least as important as stellar winds in producing dust in our Galaxy and would have been the dominant source of dust at high redshifts.

Journal Article↗
PubMed2004

A supernova origin for dust in a high-redshift quasar.

Interstellar dust plays a crucial role in the evolution of the Universe by assisting the formation of molecules, by triggering the formation of the first low-mass stars, and by absorbing stellar ultraviolet-optical light and subsequently re-emitting it at infrared/millimetre wavelengths. Dust is thought to be produced predominantly in the envelopes of evolved (age >1 Gyr), low-mass stars. This picture has, however, recently been brought into question by the discovery of large masses of dust in the host galaxies of quasars at redshift z > 6, when the age of the Universe was less than 1 Gyr. Theoretical studies, corroborated by observations of nearby supernova remnants, have suggested that supernovae provide a fast and efficient dust formation environment in the early Universe. Here we report infrared observations of a quasar at redshift 6.2, which are used to obtain directly its dust extinction curve. We then show that such a curve is in excellent agreement with supernova dust models. This result demonstrates a supernova origin for dust in this high-redshift quasar, from which we infer that most of the dust at high redshifts probably has the same origin.

Journal Article↗
PubMed2002

Prevention of sensitization to house dust mite by allergen avoidance in school age children: a randomized controlled study.

BACKGROUND: Sensitization to dust mites predisposes to asthma and allergic rhinitis, and prevention of this sensitization might reduce the rising prevalence of these disorders. OBJECTIVE: To test the effectiveness of dust mite avoidance measures on the development of sensitization to dust mites in children. METHODS: As part of a multicentre study (Study of Prevention of Allergy in Children of Europe), 242 children, aged 5-7 years, in three European countries (United Kingdom, Greece and Lithuania), were randomized to prophylactic group (n = 127) and control group (n = 115). At randomization these children were required to have a family history of atopy and positive skin test to an aeroallergen but not to house dust mite. Children in the prophylactic group were provided with dust mite impermeable mattress covers and advice on environmental measures to reduce exposure to dust-mite allergen. Control group children were given non-specific advice. After 12 months a standardized questionnaire was completed and skin prick tests were performed. RESULTS: Ten children in the prophylactic group and 19 in the control group were lost to follow-up. Three of 117 (2.56%) children in the prophylactic group and nine of 96 (9.38%) in the control group developed sensitization to dust mites. Logistic regression analysis confirmed an independent effect of prophylactic measures (adjusted odds ratio (OR): 0.14, 95% confidence interval (CI): 0.03-0.79, P = 0.03). Fifteen children need to be treated to prevent sensitization in one child. CONCLUSION: Dust mite sensitization can be reduced in school age children with simple mite avoidance measures.

Air Pollution, Indoor↗
PubMed1993

Nesting, dust bathing and perching by laying hens in cages: effects of design on behaviour and welfare.

1. Laying hens (192 ISA Brown medium hybrids) were housed from 18 to 72 weeks as groups of 4 in conventional or experimental cages. The main area of all cages provided 675 cm2/hen. All experimental cages had perches, dust baths and nest boxes, which were of three types: litter (L), artificial turf (A) or plastic rollaway (P). These facilities provided an additional 375 to 480 cm2/hen. The nest boxes and dust baths occupied either high or low positions. Behaviour, physical condition and production of the birds were regularly recorded. 2. Mortality was low (1.6% overall) and egg production very good in all treatments. The proportion of cracked and dirty eggs was slightly (but not significantly) higher in the experimental cages. In the experimental cages 90% of eggs were laid overall in the nest boxes and 3% in the dust baths. The proportion laid in the nest boxes was lower early in the laying cycle and increased with time, reaching 99% in A. 3. The facilities were heavily used. Birds spent about 25% of day time on the perches and 10-15% in or near the nest box and dust bath. At night, the majority of birds (90 to 94%) roosted on perches, but most of the remainder were on the lips of the nest box or dust bath, fouling the interiors. 4. Pre-laying behaviour was much more settled in the experimental cages (45 min spent in the eventual laying position) than in the conventional ones (20 min) and total duration varied from 68 min in A to 87 min in P. The number of nest entries varied from 3.0 (A and P) to 4.3 (L); disturbance to sitting birds was correspondingly greater in L. 5. Dust bathing in the experimental cages generally took place during the afternoon in a single bout of about 5 min duration, whereas in the conventional cages it was brief and fragmented (3 bouts of 10 s each). The dust bath was also used for foraging behaviour (pecking and scratching). The treatments with small dust baths (A and P) caused problems for the birds. 6. Feather, foot and claw damage all tended to be less in the experimental than in the conventional cages, though only in the last case was the difference significant. Keel bone depressions appeared to be associated with perches; they were present in 43% of hens in the experimental cages but only 4% in conventional cages.(ABSTRACT TRUNCATED AT 400 WORDS)

Animal Welfare↗
PubMed2004

Effects of moisture on the toxicity of inorganic and organic insecticidal dust formulations to German cockroaches (Blattodea: Blattellidae).

Toxicity of boric acid (40-99% [AI]), silica gel, eugenol, and deltamethrin dust formulations to adult male German cockroaches, Blattella germanica (L.), was evaluated at five different relative humidities ranging from 0 to 100% and in the presence of 0 to 1 ml of water. Victor boric acid dust was generally the most toxic boric acid formulation at all relative humidities, despite having the lowest percentage (40%) of boric acid; however, this was the only formulation to have sucrose and other edible ingredients. There was no consistent effect of relative humidity on dust toxicity; LT50 values of Roach Prufe (98% boric acid), Victor, and Drione (silica gel and synergized pyrethrins) increased significantly linearly with relative humidity, whereas other formulations were unaffected. The LT50 values of all boric acid-based dust formulations declined exponentially when wetted with increasing volumes of water. Water did not affect the toxicity of deltamethrin and eugenol dusts, but it caused a linear decline in toxicity of silica gel (Dri-Die). The toxicity of a formulation containing silica gel and synergized pyrethrins (Drione) increased exponentially with increasing amounts of water. Moisture in the form of relative humidity does not strongly affect the toxicity of most insecticidal dust formulations. Presence of water, however, increases the toxicity of boric acid dusts and Drione. Toxicity of the hydrophobic deltamethrin (DeltaDust) and eugenol (EcoPCO D) dusts were unaffected by water.

Animals↗
PubMed2000

Dust acoustic waves in strongly coupled dissipative plasmas

The theory of dust acoustic waves is revisited in the frame of the generalized viscoelastic hydrodynamic theory for highly correlated dusts. Physical processes relevant to many experiments on dusts in plasmas, such as ionization and recombination, dust-charge variation, elastic electron and ion collisions with neutral and charged dust particles, as well as relaxation due to strong dust coupling, are taken into account. These processes can be on similar time scales and are thus important for the conservation of particles and momenta in a self-consistent description of the system. It is shown that the dispersion properties of the dust acoustic waves are determined by a sensitive balance of the effects of strong dust coupling and collisional relaxation. The predictions of the present theory applicable to typical parameters in laboratory strongly coupled dusty plasmas are given and compared with the experiment results. Some possible implications and discrepanies between theory and experiment are also discussed.

Journal Article↗
PubMed2001

Image charge effects on electron capture by dust grains in dusty plasmas.

Electron-capture processes by negatively charged dust grains from hydrogenic ions in dusty plasmas are investigated in accordance with the classical Bohr-Lindhard model. The attractive interaction between the electron in a hydrogenic ion and its own image charge inside the dust grain is included to obtain the total interaction energy between the electron and the dust grain. The electron-capture radius is determined by the total interaction energy and the kinetic energy of the released electron in the frame of the projectile dust grain. The classical straight-line trajectory approximation is applied to the motion of the ion in order to visualize the electron-capture cross section as a function of the impact parameter, kinetic energy of the projectile ion, and dust charge. It is found that the image charge inside the dust grain plays a significant role in the electron-capture process near the surface of the dust grain. The electron-capture cross section is found to be quite sensitive to the collision energy and dust charge.

Journal Article↗