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At least 919 records · Page 51Linked to original sources
PubMed1989

[Measuring cyclone for the evaluation of dust sampling instruments SPG 10 AND SPG 210].

For dust measuring instruments which are used in industrial hygiene-according to standards there were required certain limited controls of the measurements validity. There is, however, no testing tool available, suitable for the applicants, for a gravimetric dust measuring instrument. It is proposed a measuring cyclone for industrial routine, which can be prepared and graduated with little effort. Examinations of the instruments SPG 10 and SPG 210 so far have shown a close dependence between the volume flow and the resistance to flow of the specific dust filter. The volume flow, actually effective for the grain fraction's separation of the airborne dust into certain parts of coarse dust and lung damaging fine dust in the dust precipitator's first stage may be inadmissibly different from the nominal flow. It is therefore proposed in addition to the necessary check of the measuring devices to establish the relation between volume flow and filter covering for every instrument.

Air Movements↗
PubMedDate not supplied

Preliminary study on the concentration and species composition of bacteria, fungi and mites in samples of house dust from Silesia (Poland).

Twenty-one samples of house dust collected from dwellings situated in Upper Silesia (Poland) were subjected to bacteriological, mycological and acarological examination. Moreover, in two samples the concentration of bacterial endotoxin was estimated by the use of Limulus test. The mean concentration of bacteria in the examined samples was 2831.9 thousands cfu (colony forming units) per gram, that of fungi - 28.4 thousands cfu per gram, and that of mites - 51.5 specimens per gram. No significant correlation could be found between the numbers of these three components of house dust. Two examined samples of house dust contained high amounts of bacterial endotoxin which are comparable to the concentration of endotoxin in agricultural dusts, and could be of immunopathogenic significance. In the bacterial flora of the examined house dust samples, staphylococci prevailed in 45.9% of all isolates, streptococci (23.2%), corynebacteria (13.9%) and spore-forming bacilli (12.2%). Among fungi, the most numerous were strains of the genus Penicillium (39.4%), yeasts (29.5%) and strains of the genus Aspergillus (8.4%). Both bacteria and fungi comprise species that are known for their allergenic properties. The mite fauna of the examined samples was dominated by Dermatophagoides farinae (62.7% of all specimens) and Dermatophagoides pteronyssinus (30.4%); both species are known as important allergens of house dust. The results hitherto obtained indicate the potential significance of all the investigated components (bacteria, fungi and mites) in causing allergy to house dust.

Animals↗
PubMed1985

[Mites in house dust and human allergoses].

The literary data on the study of the house-dust mites during the period from 1864 till 1983 are given. The methods of the house dust samples collection in flats and the methods of the house-dust mites isolation from the house dust are evaluated. The house-dust mites fauna including more than 130 species is described. The synantropic mites-pyroglyphides are the main part of the fauna, the stored products mites and predatory cheyletid and gamasid mites occur regularly. The rest part of the fauna consists of the different mites got into house by chance. The literary data on the influence of temperature and relative humidity on the development and growth of the mite population are given. The house-dust mites feeding and digestion processes bearing relation to the formation of the mite allergen are reviewed. The original data complete the literary data on the fauna and distribution of the house-dust mites in Moscow.

Allergens↗
PubMed1979

[Effect of metal dust on the respiratory system. I. Experimental studies].

The Wistar rats were intratracheally administered 50 mg of PbO dust, the same amounts of metalliferous dust from one of lead--and zinc works and of ferrotungsten dust, and 10--15 mg of cadmium dust (greater doses of cadmium dust resulted in animals' death). After 6 months, and in the case of cadmium dust after 9--12 months, the animals were dissected and their lungs were morphologically examined and hydroxyproline level was determined. In all groups hydroxyproline was found to be increased but fibrosis was different, especially in the group exposed to cadmium dust.

Animals↗
PubMed1980

[Evaluation of working environment in the textile industry. IV. Dust concentration in the air of the flax spinning and weaving plants].

Evaluation of dust concentration in the air of spinning and weaving rooms was made by gravimetric sampling of dust in 3 flax plants, where short flax fibres (flax--tow) and long flax fibres were manufactured. Besides, the dispersion of dusts and concentration of free silica were determined. The highest concentration of dust (10 mg/m3) was found in hackling room, mixing mill, and the one where spreading machines are operated, while in the carding room it was - 7.0 mg/m3. In other shops the concentration was - 5.5 mg/m3. The dust in the air of spinning rooms contained 2.3% of free silica and 53% of its particles were smaller than 5 micrometers. In the weaving rooms it contained 1.6% of free silica and 57% particles were smaller than 5 micrometers. The geometric mean of dust concentration higher than MAC for vegetable dusts (4 mg/m3) was found in hackling mill, mixing mill and the one where spreading machines are operated.

Air Pollutants↗
PubMed1984

[Biological evaluation of the aggressiveness of copper slag dust].

By hemolytic, intraperitoneal and intratracheal tests, biological effects of the copper slag dust, which has recently been used in casts cleaning processes, have been investigated. It was found that the copper slag dust is not biologically inert. It exhibits slight fibrogenic properties resulting in fibrous changes after lung administration. The fibrosis resembles that of collagenosis. The fibrous reaction, in form of granulomas with developed procollagenic fibres, was found on intraperitoneal dust administration. Three and six months after intratracheal insufflation of 50 mg of the dust a significant increase in the content of hydroxyproline and lipids in lungs, as compared to controls, was found. Histopathological test revealed the connective tissue multiplication, of focal type, around dust clusters, forming granulomas consisting of macrophages and other mononuclear cells. In the hemolytic test the slag dust induced hemolysis of 7% ram erythrocytes. The test dust should be classified as weakly fibrogenic.

Animals↗
PubMed1984

[Occurrence of phenolic compounds in the dust of swine stalls and henhouses].

Dust-borne phenols and indols were extracted by ethanol from the sedimentation dust of two pig houses (finishing pigs on half slatted floor resp. piglets on deep litter) and a hen house (3-stage battery cages) and analysed by gas chromatography. In the dust of both pig houses 5 compounds (phenol, p-cresol, p-ethylphenol, indole, skatole) and in the hen house 6 compounds (phenol, p-cresol, 2.6-dimethylamine, 3.4-dimethylamine, indole, skatole) were found. The total amounts of the phenolic compounds came to 275 microgram/g dust (finishing pigs), 111 micrograms/g dust (piglets) and 108 micrograms/g dust (hens). Quantitatively in the finishing pig house p-cresol is well to the fore (53% of the total amount), in the piglet house phenol is dominating (50%) and in the hen house 2.6-dimethylphenol dominates distinctly (83%). The sensory evaluation of the two pig houses showed that the odour intensity in the finishing pig house is distinctly higher than in the piglet house. It seems that the decrease of the odour intensity coincides with the decrease of p-cresol. The results show that animal house dust is an important carrier of trace gases including odorants. The possible influence of dustborne phenol and skatole on the animals is discussed with respect to respiratory affections.

Animals↗
PubMed1978

The cytotoxic effects of asbestos and other mineral dust in tissue culture cell lines.

The cytotoxic effects of 15 dusts have been tested in 2 cell lines. Experimental animal data are available for 11 of the 15 dusts. There is a correlation between the cytotoxic activities of the dusts and the ability to induce mesothelial tumours following intrapleural injection of the dusts. Some preliminary observations on the nature of interaction between the dusts, medium components and the cells are reported. It is suggested that the study of the interactions between cells and dusts in culture may lead to an understanding of the pathogenesis of these dusts in man and animals.

Asbestos↗
PubMedDate not supplied

Fine particles of cotton dust influence histamine release.

Cotton dust particle distribution in respiratory airways was measured to determine if specific size particles of the heterogeneous dust are concentrated as a function of airway diameter. Previously reported work indicated that the fine particles are responsible for the decrement in pulmonary function which occurs subsequent to cotton dust inhalation. After recovery, particles were sized and counted microscopically. Significant increases in fine particles (5-7 mu) were found in all airways of exposed animals as compared with controls. These particles become more concentrated as the airway diameter decreased. Histamine determinations were made in mice lungs after the animals were exposed to cotton dust for various periods of time to see if such treatment could be correlated with elevations in the concentrations of this biogenic amine. Lung histamine increased as exposure time to cotton dust increased. It is concluded that the lung histamine release occurring after cotton dust inhalation is related to some property of the fine particles of the heterogeneous dust.

Animals↗
PubMedDate not supplied

[Correlation between the prick test and specific IgE against allergens of house dust and Dermatophagoides sp].

Of the techniques which are usually used for the in vitro etiologic diagnosis of determined allergic processes, it is the RAST technique which is most widely used for determining specific antibodies of the IgE class. On the other hand, also of interest is the quantification of total IgE in these patients. We have studied 80 allergic and non allergic patients in order to evaluate the possible correlation between the Prick and the RAST tests applied to different allergens such house dust. Dermatophagoides pteronyssinus and Dermatophagoides farinae. The patients were distributed in four groups in relation to the clinical history and serum levels of total IgE, as follows: Group I: Patients with positive clinical history and increases levels of total IgE. Group II: patients with positive history and normal values of total IgE. Group III: patients with negative history and increased levels of serum IgE, and Group IV with non atopic subjects with normal values of IgE. The results show a high correlation between both tests for house dust mite allergens in the group I. The relation to inferior in the group II. As far as house dust is concerned, there is no correlation between the cutaneous test in the RAST test even in the group with positive clinical history. The data observed with house dust mites suggest a relation between the clinical history and the cutaneous test and also between the RAST and the levels of total serum IgE. These relations are not fund with house dust. It is discussed the validity and applications of both tests to the diagnosis of immediate hypersensitivity reactions to house dust mites and house dust.

Adolescent↗
PubMed1994

Comparison between the Acarex R test and a Der p 1 ELISA for the detection of house-dust mites in the homes of asthma sufferers.

Exposure to house-dust mite allergens in early childhood is an important determinant of the subsequent development of asthma. The Acarex R semi-quantitative test (Noristan) is marketed for use in patients' homes to assess mite levels in house dust. In order to evaluate the reliability of the test in a coastal area where house-dust mites are known to be prevalent, house-dust mite levels were estimated in 119 dust samples obtained from the homes of asthmatic children in a comparative study, by means of the Acarex R test and a Der p 1 enzyme-linked immunosorbent assay (ELISA). A linear regression of the 4 Acarex classes against log Der p 1 revealed a significant correlation (P = 0,0001) but there was a poor correlation between low Acarex R scores and the Der p 1 allergen levels determined by ELISA. Acarex R scores of 2 and 3 were usually associated with Der p 1 levels greater than 10 micrograms/g dust. Our studies indicate that the Acarex R test will identify high levels of mite allergens. Although its application may be limited in coastal areas such as the Cape Peninsula, it may be more useful inland, in climates where house-dust mites are not commonly encountered in all homes.

Allergens↗
PubMed1993

Alteration in the modulatory role of respiratory epithelium after exposure of guinea pigs to respirable cotton dust.

Chest tightness may occur after inhalation of cotton dust. To understand the origins of this symptom of byssinosis, we exposed guinea pigs to respirable cotton dust and determined whether the resulting pulmonary obstruction was associated with alterations in the in vitro reactivity of the trachea to methacholine. The isolated, perfused trachea preparation was utilized because it allows a comparison of airway smooth muscle responses to drugs after they are applied separately to the mucosal or serosal surfaces. In epithelium-containing control tracheae, mucosally applied methacholine was less potent and elicited smaller maximum contractile responses than those obtained when it was applied to the serosal compartment. After a 6-h inhalation exposure to 30 mg/m3 respirable cotton dust, the mucosal maximum response to methacholine was substantially increased immediately (0 h) after the end of the exposure, but it was decreased 18 h postexposure. A dust level of 10 mg/m3 produced modest increases in the mucosal maximum responses at both postexposure periods, elevating them to the magnitude of the extraluminal maximum response. The potency of serosally applied methacholine was not affected by any cotton dust exposure. Mechanical epithelium removal increased mucosal reactivity to the serosal level in both control and cotton (30 mg/m3)-exposed groups, and abolished the effects of dust on mucosal reactivity to methacholine. Our findings suggest that the modulatory effect of the epithelium may be inhibitory or excitatory. The balance between the two influences may be altered by inhaled cotton dust.

Administration, Inhalation↗
PubMed1998

House dust mite allergen accumulation on sheepskins.

AIM: Sheepskins, which are often used as infant bedding in New Zealand, are known to harbour large quantities of house dust mites and their allergens. In this study we determined the rate of accumulation of the house dust mite allergen, Der p 1 on new sheepskins, and the effects of washing and dry cleaning on its removal. METHODS: New sheepskins were placed on living-room floors (n = 6) and mattresses (n = 6) in six domestic dwellings in Wellington. Sheepskin dust samples were collected by vacuuming before placement, and at two, four and six weeks, after which they were warm-washed. They were replaced for a further six weeks, then dry-cleaned. Dust samples were collected before and after washing and dry-cleaning, and from mattresses and living-room floors. Dust samples were analysed for Der p 1 by double monoclonal antibody ELISA. RESULTS: Der p 1 levels rapidly increased in sheepskins placed on living-room floors and mattresses to a geometric mean level (range) of 9.0 micrograms/g (1.1-102.2) and 29.4 micrograms/g (5.3-131.1) at six weeks, respectively. After warm-water washing and replacement for a further six weeks, these levels were higher at 75.5 micrograms/g (50.1-260.4) and 31.9 micrograms/g (11.1-75.2), respectively. Sheepskin Der p 1 accumulation correlated with mattress (r = 0.78), and living-room floor Der p 1 levels (r = 0.94). Warm water washing and dry-cleaning reduced sheepskins Der p 1 levels by a mean of 79.2% and 95.3%, respectively. CONCLUSIONS: Sheepskins rapidly accumulate house dust mite allergens from the domestic environment. Due to very high levels and rapid accumulation of Der p 1, sheepskins as infant bedding should be discouraged for infants at risk of sensitisation to house dust mites. If they are to be used then it is important that they are washed or dry-cleaned regularly.

Allergens↗
PubMed1999

[House dust mite allergens and mite allergy in Copenhagen dwellings. A cross-sectional study].

The aim of the study was to investigate the influence of various environmental factors on occurrence of house dust mite allergens and the influence of allergen exposure on mite allergy. Ninety-two persons from a population study filled in a questionnaire, were skin prick and lung function tested and dust samples were collected from their mattresses for analyses. Two out of five patients with asthma had a positive skin reaction to house dust mite allergen in contrast to five out of 87 non-asthmatics. Fifty-nine per cent of the dust samples contained (group 1) mite allergen > 2 micrograms/g dust. Such mattresses were older (median 7 years, range 1-22) than mattresses with less allergen (median 4 years, range 1-20). In the six bedrooms reported to be humid or mouldy, mattresses contained high concentration of mite allergens. No other parameter investigated could predict the allergen contents. In almost all cases dust analyses are crucial to be able to advise patients with house dust mite allergy.

Air Pollution, Indoor↗
PubMed1993

Airflow obstruction in nonsmoking, asbestos- and mixed dust-exposed workers.

Obstructive changes in small airways have been described in patients exposed to asbestos and other mineral dusts. The physiologic significance of these small airways abnormalities and their relationship to dust burden and alveolitis remain unclear. We performed bronchoalveolar lavage (BAL) in 30 nonsmoking and 30 age-matched smoking subjects, all with mild asbestos and mixed dust exposure, to determine if parameters of lung dust burden correlated with spirometric evidence of airflow obstruction. Seventeen of 30 nonsmoking subjects and 24 of 30 smoking subjects met spirometric criteria for airflow obstruction. There were significantly more obstructed subjects in both dust exposed groups (P < 0.05) than in an age-matched nondust exposed group. There was, however, no significant difference in the number of obstructed subjects between the smoking and nonsmoking groups. There was no correlation in either group between airflow obstruction and total or differential cell counts, ferruginous bodies, total asbestos fibers, or the percent of free silica in the particulate fraction recovered by BAL. We conclude that evidence of small airways obstruction occurs commonly in occupationally dust exposed subjects and appears to be related to dust exposure per se and not to alveolar inflammation or fiber retention, important factors in the development of alveolitis and interstitial lung disease.

Asbestos↗
PubMed1998

Direct measurements of temperature and humidity in dust mite microhabitats.

BACKGROUND: Up to 70% of atopic asthmatics have a positive skin test to the dust mite allergen Der p 1. Reduction of dust mite numbers by lowering room humidity control is one suggested technique for reducing dust mite allergen levels to clinically acceptable levels. Trials of this technique in temperate climates have reported mixed results. It has been speculated that one reason for this is that humidity changes in room ambient air are not tightly linked to humidity changes in the dust mite microenvironment (in the base of carpets, bedding, furniture etc.). OBJECTIVE: To directly measure humidities and temperatures in dust mite microenvironments and compare these to ambient conditions, and so gather data on how the microclimates are influenced by room conditions and moisture and heat sources, such as an occupant in a bed. METHODS: A special small humidity device has been developed which can discriminate humidity changes over distances of millimetres. With these devices microclimates have been measured in the base of carpets, in layers through bedding, and in furniture. RESULTS: Measured base-of-carpet humidities were significantly higher than room humidities. Bedding relative humidities show complex behaviour according to the distance separation between the measuring point and the occupant. Immediately below the occupant, bed relative humidities fall when the person enters the bed. Similar behaviour is observed in a sofa. CONCLUSION: Some dust mite microclimates have been shown to be very different from room conditions. Consequently, reduction of dust mite numbers and allergen levels cannot be guaranteed by the controlling of room humidities.

Allergens↗
PubMed2001

Commercial availability of a house dust mite patch test.

The house dust mite long has been studied for its potential role in atopic dermatitis. Its part in the pathogenesis of asthma and allergic rhinitis has been studied and is accepted. Testing for the dust mite allergen in this arena is performed with radioallergosorbent tests (RASTs) and prick testing. For several reasons, including the lack of a standardized testing tool, the difficulty in removing dust from the environment and the lack of association of dust and skin disease by patients, the role of the house dust mite in the pathogenesis of atopic dermatitis and skin disease has been questioned. Chemotechnique Diagnostics (Malmo, Sweden) now provides a standardized dust mite allergen in petrolatum in 2 concentrations. Dermatophagoides mix is a 50:50 mix of Dermatophagoides pteronyssinus and D. farinae at concentrations of 20% and 30%. The availability of a standardized patch test allergen for the house dust mite provides a better tool to investigate the role of this allergen as a contactant.

Animals↗
PubMed1999

Intergalactic cold dust in the NGC 4631 group.

We have detected extraplanar cold dust at distances out to >10 kiloparsecs, situated in the halo of the interacting galaxy NGC 4631. The dust emission disk is much thinner than the warped HI disk, and new structures emerge. In particular, a giant arc has been found that is linked to anomalies in the kinematical structure of the atomic gas. Most of the extraplanar dust is closely associated with HI spurs that have been found earlier [Weliachew, L., Sancisi, R. & Guelin, M. (1978) Astron. Astrophys. 65, 37-45; Rand, R. J. (1994) Astron. Astrophys. 285, 833-856]. These spurs obviously are traces of the interaction [Combes, F. (1978) Astron. Astrophys. 65, 47-55]. The dust emission within the plane reaches the border of the optical disk. The activity of the disk of NGC 4631 is moderately enhanced by the interaction, but no gas moving in the z-direction could be found [Rand, R. J., Kulkarni, S. R. & Hester, J. J. (1992) Astrophys. J. 396, 97-103; Golla, G., Dettmar, R.-J. & Domgorgen, H. (1996) Astron. Astrophys. 313, 439-447]. Hence, it seems unlikely that strong winds have deposited the high-z dust. Instead, the coincidence with the HI features suggests that we see a track left behind by the interaction. In addition, the HI shows a supershell formed by an impact [Rand, R. J. & Stone, J. M. (1996) Astron. J. 111, 190-196] in the zone where the dust trail crosses the disk. This region is also characterized by disturbances in the distribution of the Halpha light. The masses associated with the dust can be estimated only very roughly on the basis of the existing data; they are of the order of a few 10(9) M middle dot in circle of gas.

Journal Article↗